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Cossa D, Dang DH, Knoery J, Patel-Sorrentino N, Tessier E, Démoulin L, Garnier C. Sources, chronology of deposition, and mobility of mercury and methylmercury in the sediments of a contaminated Mediterranean bay. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 949:175021. [PMID: 39094652 DOI: 10.1016/j.scitotenv.2024.175021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/03/2024] [Accepted: 07/23/2024] [Indexed: 08/04/2024]
Abstract
Coastal sediments constitute a major reservoir for natural and anthropogenic mercury (Hg) and can be used as geochronological records of past Hg deposition. They may also act as secondary Hg sources for pelagic ecosystems via the efflux of toxic methylmercury (MeHg) diffusing from sediment porewaters and/or mobilized by sediment resuspension. In Toulon Bay sediments, which are known as one of the Hg hot spots of the northwestern Mediterranean Sea, we explored Hg species accumulation and mobility. The total Hg concentrations averaged 0.014 μg g-1 ca. 2000 years ago, then exhibited three major peaks during the Medieval Period, the Early Modern Period of Europe, and the Industrial Era, reaching 0.06, 0.07, and 13 μg g-1, respectively. The Medieval peak is attributed to the massive development of metallurgy in Europe accompanied by the burning of soil and vegetation, the second peak to the optimum of Hg extraction in Europe (Almadén mine), and the resumption of deforestation after the great plague. The third most recent Hg enrichment is associated with Hg-fulminate production, the scuttling of the French navy fleet during World War II, and ship salvaging and removal in the post-war years. Sampling of the dissolved phase at high vertical resolution above and below the sediment-water interface (SWI) enables us to conclude that MeHg was produced in situ by microbiological pathways and its diffusion across the SWI was negligible. On the other hand, ex-situ resuspension experiments showed that sorption and/or photodemethylation restrict MeHg from the dissolved phase.
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Affiliation(s)
- Daniel Cossa
- Université Grenoble Alpes, ISTerre, CS40700, 38058 Grenoble Cedex 9, France; IFREMER, Contamination Chimique des Ecosystèmes Marins (CCEM), BP21105, 44311 Nantes, France.
| | - Duc Huy Dang
- Laboratoire MIO, Université de Toulon, BP20132, 83957 La Garde, France; Trent University, School of the environment and Department of Chemistry, 1600 W Bank Dr, Peterborough, ON K9L0G2, Canada
| | - Joël Knoery
- IFREMER, Contamination Chimique des Ecosystèmes Marins (CCEM), BP21105, 44311 Nantes, France
| | | | - Erwan Tessier
- Laboratoire MIO, Université de Toulon, BP20132, 83957 La Garde, France
| | - Léo Démoulin
- IFREMER, Contamination Chimique des Ecosystèmes Marins (CCEM), BP21105, 44311 Nantes, France
| | - Cédric Garnier
- Laboratoire MIO, Université de Toulon, BP20132, 83957 La Garde, France
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Fang K, He Y, Xu J, Shi J. Synchronous influence of soil amendments on alkylmercury and methane emissions in mercury-contaminated paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174415. [PMID: 38969116 DOI: 10.1016/j.scitotenv.2024.174415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/25/2024] [Accepted: 06/29/2024] [Indexed: 07/07/2024]
Abstract
Mercury (Hg) alkylation and methane (CH4) emissions pose significant global concerns. Paddy soil, due to its long-term anaerobic conditions and abundant organic matter, is hotspots for soil Hg alkylation and CH4 emissions. However, the relevance between Hg alkylation and CH4 emissions, especially their simultaneous reduction strategies, remains poorly understood. Here, we investigated the effects of biochar (BC), selenium (Se) and rice straw (RS) amendments on Hg alkylation and CH4 emissions in paddy soil, and the accumulation of Hg speciation. Results found that both BC and RS amendments significantly increased the levels of soil organic carbon (SOC) and humification index (HIX). Furthermore, BC decreased the concentrations of Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) by 63.1%, 53.6% and 100% in rice grains. However, RS increased Hg(II) concentration but decreased the total Hg (THg), MeHg and EtHg concentrations in rice grains. Compared to the CK, RS significantly increased CH4 emissions, while BC decreased CH4 emissions, and Se showed no significant difference. Se amendment increased the Hg(II) and EtHg concentrations by 20.3% and 17.0% respectively, and decreased the MeHg concentration in grains by 58.3%. Both BC and RS impacted the abundance of methanogens by enhancing SOC and HIX, subsequently modulating the relevance between Hg alkylation and CH4 emissions. These findings provide insights into the relevance between Hg alkylation and CH4 emissions and propose potential mitigation mechanisms in Hg-contaminated paddy soil.
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Affiliation(s)
- Kaikai Fang
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yan He
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, Hangzhou 310058, China
| | - Jianming Xu
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jiachun Shi
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
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Wang Y, Zhang L, Chen X, Li C, Ding S, Yan J, Xiao J, Wang B, Xu L, Hang X. Algal-derived dissolved organic matter accelerates mercury methylation under cyanobacterial blooms in the sediment of eutrophic lakes. ENVIRONMENTAL RESEARCH 2024; 251:118734. [PMID: 38493854 DOI: 10.1016/j.envres.2024.118734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 02/17/2024] [Accepted: 03/14/2024] [Indexed: 03/19/2024]
Abstract
Mercury (Hg), especially in the form of methylmercury (MeHg), poses a significant threat to both organisms and the environment due to its extreme toxicity. While methylation process of Hg in sediments has been extensively studied, recognition of its associated risks and mechanisms during cyanobacterial blooms remains limited. This study investigated the distribution characteristics of Hg and MeHg in sediments of Taihu Lake, China. The concentration of Hg and MeHg varied within the range of 96.0-212.0 ng g-1 and 0.1-0.5 ng g-1, respectively. Higher ecological risks of Hg were found in algal-dominated regions compared to macrophyte areas. The significant correlations observed between Hg, MeHg, and algal-derived dissolved organic matter (ADOM) components C1 and C2 in algal-dominated regions indicate a close association between ADOM components and the Hg methylation process. These components are involved in the absorption or complexation of Hg, participate in redox reactions, and modulate microbial activity. The dsrB gene in sulfate-reducing bacteria (SRB) was found to accelerate the metabolic pathways of Hg methylation. These findings indicate that ADOM could enhance the methylation process of Hg during cyanobacterial blooms, which warrants attention.
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Affiliation(s)
- Yan Wang
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Lan Zhang
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Xiang Chen
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Cai Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Shiming Ding
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Jiabao Yan
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Jing Xiao
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Bin Wang
- Zhongyifeng Construction Group Co., Ltd., Suzhou, 215131, China
| | - Lv Xu
- Anhui Urban Construction Design Institute Corp., Ltd, Hefei, 230051, China
| | - Xiaoshuai Hang
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China.
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Scuvée D, Goñi-Urriza M, Tessier E, Gassie C, Ranchou-Peyruse M, Amouroux D, Guyoneaud R, Khalfaoui-Hassani B. Molybdate inhibits mercury methylation capacity of Pseudodesulfovibrio hydrargyri BerOc1 regardless of the growth metabolism. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:42686-42697. [PMID: 38878247 DOI: 10.1007/s11356-024-33901-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 05/31/2024] [Indexed: 07/04/2024]
Abstract
Molybdate inhibits sulfate respiration in sulfate-reducing bacteria (SRB). It is used as an inhibitor to indirectly evaluate the role of SRB in mercury methylation in the environment. Here, the SRB Pseudodesulfovibrio hydrargyri BerOc1 was used to assess the effect of molybdate on cell growth and mercury methylation under various metabolic conditions. Geobacter sulfurreducens PCA was used as the non-SRB counterpart strain with the ability to methylate mercury. While PCA growth and methylation are not affected by molybdate, 1 mM of molybdate inhibits BerOc1 growth under sulfate respiration (50% inhibition) but also under fumarate respiration (complete inhibition). Even more surprising, mercury methylation of BerOc1 is totally inhibited at 0.1 mM of molybdate when grown under sulfate or fumarate respiration with pyruvate as the electron donor. As molybdate is expected to reduce cellular ATP level, the lower Hg methylation observed with pyruvate could be the consequence of lower energy production. Although molybdate alters the expression of hgcA (mercury methylation marker) and sat (involved in sulfate reduction and molybdate sensitivity) in a metabolism-dependent manner, no relationship with mercury methylation rates could be found. Our results show, for the first time, a specific mercury methylation inhibition by molybdate in SRB.
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Affiliation(s)
- Diva Scuvée
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Marisol Goñi-Urriza
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Emmanuel Tessier
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Claire Gassie
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | | | - David Amouroux
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Rémy Guyoneaud
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
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Lawruk-Desjardins C, Storck V, Ponton DE, Amyot M, Walsh DA. A genome catalogue of mercury-methylating bacteria and archaea from sediments of a boreal river facing human disturbances. Environ Microbiol 2024; 26:e16669. [PMID: 38922750 DOI: 10.1111/1462-2920.16669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 05/23/2024] [Indexed: 06/28/2024]
Abstract
Methyl mercury, a toxic compound, is produced by anaerobic microbes and magnifies in aquatic food webs, affecting the health of animals and humans. The exploration of mercury methylators based on genomes is still limited, especially in the context of river ecosystems. To address this knowledge gap, we developed a genome catalogue of potential mercury-methylating microorganisms. This was based on the presence of hgcAB from the sediments of a river affected by two run-of-river hydroelectric dams, logging activities and a wildfire. Through the use of genome-resolved metagenomics, we discovered a unique and diverse group of mercury methylators. These were dominated by members of the metabolically versatile Bacteroidota and were particularly rich in microbes that ferment butyrate. By comparing the diversity and abundance of mercury methylators between sites subjected to different disturbances, we found that ongoing disturbances, such as the input of organic matter related to logging activities, were particularly conducive to the establishment of a mercury-methylating niche. Finally, to gain a deeper understanding of the environmental factors that shape the diversity of mercury methylators, we compared the mercury-methylating genome catalogue with the broader microbial community. The results suggest that mercury methylators respond to environmental conditions in a manner similar to the overall microbial community. Therefore, it is crucial to interpret the diversity and abundance of mercury methylators within their specific ecological context.
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Affiliation(s)
| | - Veronika Storck
- Department of Biology, Concordia University, Montreal, Quebec, Canada
- Département de sciences biologiques, Université de Montréal, Montreal, Quebec, Canada
| | - Dominic E Ponton
- Département de sciences biologiques, Université de Montréal, Montreal, Quebec, Canada
| | - Marc Amyot
- Département de sciences biologiques, Université de Montréal, Montreal, Quebec, Canada
| | - David A Walsh
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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Chaudhary DK, Seo D, Han S, Hong Y. Distribution of mercury in modern bottom sediments of the Beaufort Sea in relation to the processes of early diagenesis: Microbiological aspect. MARINE POLLUTION BULLETIN 2024; 202:116300. [PMID: 38555803 DOI: 10.1016/j.marpolbul.2024.116300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/23/2024] [Accepted: 03/24/2024] [Indexed: 04/02/2024]
Abstract
This study investigated the contents of total mercury (THg), trace metals, and CH4 and determined the signature microbes involved in various biogeochemical processes in the sediment of the Canadian Beaufort Sea. The THg ranged between 32 and 63 μg/kg and the trace metals such as Fe, Al, Mn, and Zn were significant in distributions. The pH, SO42-, Fe2+, and redox proxy metals were crucial factors in the spatial and vertical heterogeneity of geochemical distributions. CH4 was detected only at the mud volcano site. Microbial analyses identified Clostridium, Desulfosporosinus, Desulfofustis, and Desulftiglans as the predominant Hg methylators and sulfate reducers; Nitrosopumilus and Hyphomicrobium as the major nitrifiers and denitrifiers; Methanosarcina and Methanosaeta as keystone methanogens; and Methyloceanibacter and Methyloprofundus as signature methanotrophs. Altogether, this study expands the current understanding of the microbiological and geochemical features and could be helpful in predicting ecosystem functions in the Canadian Beaufort Sea.
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Affiliation(s)
- Dhiraj Kumar Chaudhary
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea
| | - DongGyun Seo
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea
| | - Seunghee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-ro, Gwangju 61005, Republic of Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea.
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Zhang X, Li Q, Zhong Z, Huang Z, Bian F. Characterization of the composition, structure, and functional potential of bamboo rhizosphere archaeal communities along a chromium gradient. Front Microbiol 2024; 15:1372403. [PMID: 38694797 PMCID: PMC11061513 DOI: 10.3389/fmicb.2024.1372403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/29/2024] [Indexed: 05/04/2024] Open
Abstract
Introduction Bamboo can be used in the phytoremediation of heavy metal pollution. However, the characteristics of the bamboo rhizosphere archaeal community in Cr-contaminated soil under field conditions remain unclear. Methods In this study, high-throughput sequencing was used to examine the rhizosphere soil archaeal communities of Lei bamboo (Phyllostachys precox) plantations along a Cr pollution gradient. Results The results revealed U-shaped relationships between Cr [total Cr (TCr) or HCl-extractable Cr (ACr)] and two alpha indices (Chao1 and Shannon) of archaea. We also established that high Cr concentrations were associated with a significant increase in the abundance of Thaumarchaeota and significant reductions in the abundances of Crenarchaeota and Euryarchaeota. The archaeal co-occurrence networks reduced in complexity with Cr pollution, decreasing the community's resistance to environmental disturbance. Candidatus nitrosotalea and Nitrososphaeraceae_unclassified (two genera of Thaumarchaeota) were identified as keystone taxa. The community structure of soil archaeal communities was also found to be affected by TCr, ACr, pH, total organic C, and available nutrient (N, P, and K) concentrations, with pH being identified as the most reliable predictor of the archaeal community in assessed soils. Discussion These findings enhance our understanding of microbial responses to Cr pollution and provide a basis for developing more refined approaches for the use of bamboo in the remediation of Cr-contaminated soils.
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Affiliation(s)
- Xiaoping Zhang
- Key Laboratory of State Forestry and Grassland Administration on Bamboo Forest Ecology and Resource Utilization, China National Bamboo Research Center, Hangzhou, China
- National Long-term Observation and Research Station for Forest Ecosystem in Hangzhou-Jiaxing-Huzhou Plain, Hangzhou, China
- Engineering Research Center of Biochar of Zhejiang Province, Hangzhou, China
| | - Qiaoling Li
- Key Laboratory of State Forestry and Grassland Administration on Bamboo Forest Ecology and Resource Utilization, China National Bamboo Research Center, Hangzhou, China
- National Long-term Observation and Research Station for Forest Ecosystem in Hangzhou-Jiaxing-Huzhou Plain, Hangzhou, China
| | - Zheke Zhong
- Key Laboratory of State Forestry and Grassland Administration on Bamboo Forest Ecology and Resource Utilization, China National Bamboo Research Center, Hangzhou, China
- National Long-term Observation and Research Station for Forest Ecosystem in Hangzhou-Jiaxing-Huzhou Plain, Hangzhou, China
- Key Laboratory of High Efficient Processing of Bamboo of Zhejiang Province, Hangzhou, China
| | - Zhiyuan Huang
- Key Laboratory of State Forestry and Grassland Administration on Bamboo Forest Ecology and Resource Utilization, China National Bamboo Research Center, Hangzhou, China
- National Long-term Observation and Research Station for Forest Ecosystem in Hangzhou-Jiaxing-Huzhou Plain, Hangzhou, China
| | - Fangyuan Bian
- Key Laboratory of State Forestry and Grassland Administration on Bamboo Forest Ecology and Resource Utilization, China National Bamboo Research Center, Hangzhou, China
- National Long-term Observation and Research Station for Forest Ecosystem in Hangzhou-Jiaxing-Huzhou Plain, Hangzhou, China
- Key Laboratory of High Efficient Processing of Bamboo of Zhejiang Province, Hangzhou, China
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Peng X, Yang Y, Yang S, Li L, Song L. Recent advance of microbial mercury methylation in the environment. Appl Microbiol Biotechnol 2024; 108:235. [PMID: 38407657 PMCID: PMC10896945 DOI: 10.1007/s00253-023-12967-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/02/2023] [Accepted: 12/13/2023] [Indexed: 02/27/2024]
Abstract
Methylmercury formation is mainly driven by microbial-mediated process. The mechanism of microbial mercury methylation has become a crucial research topic for understanding methylation in the environment. Pioneering studies of microbial mercury methylation are focusing on functional strain isolation, microbial community composition characterization, and mechanism elucidation in various environments. Therefore, the functional genes of microbial mercury methylation, global isolations of Hg methylation strains, and their methylation potential were systematically analyzed, and methylators in typical environments were extensively reviewed. The main drivers (key physicochemical factors and microbiota) of microbial mercury methylation were summarized and discussed. Though significant progress on the mechanism of the Hg microbial methylation has been explored in recent decade, it is still limited in several aspects, including (1) molecular biology techniques for identifying methylators; (2) characterization methods for mercury methylation potential; and (3) complex environmental properties (environmental factors, complex communities, etc.). Accordingly, strategies for studying the Hg microbial methylation mechanism were proposed. These strategies include the following: (1) the development of new molecular biology methods to characterize methylation potential; (2) treating the environment as a micro-ecosystem and studying them from a holistic perspective to clearly understand mercury methylation; (3) a more reasonable and sensitive inhibition test needs to be considered. KEY POINTS: • Global Hg microbial methylation is phylogenetically and functionally discussed. • The main drivers of microbial methylation are compared in various condition. • Future study of Hg microbial methylation is proposed.
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Affiliation(s)
- Xuya Peng
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China
| | - Yan Yang
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China
| | - Shu Yang
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China.
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
| | - Lei Li
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China
| | - Liyan Song
- School of resources and environmental engineering, Anhui University, No 111 Jiulong Road, Economic and Technology Development Zone, Hefei, 230601, People's Republic of China.
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Zhou Y, Li S, Hintelmann H, Tang W, Zhong H. New insights into HgSe antagonism: Minor impact on inorganic Hg mobility while potential impacts on microorganisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 913:169705. [PMID: 38160847 DOI: 10.1016/j.scitotenv.2023.169705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/13/2023] [Accepted: 12/25/2023] [Indexed: 01/03/2024]
Abstract
Selenium (Se) is a crucial antagonistic factor of mercury (Hg) methylation in soil, with the transformation of inorganic Hg (IHg) to inert mercury selenide (HgSe) being the key mechanism. However, little evidence has been provided of the reduced Hg mobility at environmentally relevant doses of Hg and Se, and the potential impacts of Se on the activities of microbial methylators have been largely ignored. This knowledge gap hinders effective mitigation for methylmercury (MeHg) risks, considering that Hg supply and microbial methylators serve as materials and workers for MeHg production in soils. By monitoring the mobility of IHg and microbial activities after Se spike, we reported that 1) active methylation might be the premise of HgSe antagonism, as higher decreases in MeHg net production were found in soils with higher constants of Hg methylation rate; 2) IHg mobility did not significantly change upon Se addition in soils with high DOC concentrations, challenging the long-held view of Hg immobilization by Se; and 3) the activities of iron-reducing bacteria (FeRB), an important group of microbial methylators, might be potentially regulated by Se addition at a dose of 4 mg/kg. These findings provide empirical evidence that IHg mobility may not be the limiting factor under Se amendment and suggest the potential impacts of Se on microbial activities.
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Affiliation(s)
- Yang Zhou
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Holger Hintelmann
- Department of Chemistry, Trent University, Peterborough, ON, Canada; Water Quality Centre, Trent University, Peterborough, ON, Canada
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
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Nelson SJ, Willacker J, Eagles-Smith C, Flanagan Pritz C, Chen CY, Klemmer A, Krabbenhoft DP. Habitat and dissolved organic carbon modulate variation in the biogeochemical drivers of mercury bioaccumulation in dragonfly larvae at the national scale. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169396. [PMID: 38114036 DOI: 10.1016/j.scitotenv.2023.169396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/21/2023]
Abstract
We paired mercury (Hg) concentrations in dragonfly larvae with water chemistry in 29 U.S. national parks to highlight how ecological and biogeochemical context (habitat, dissolved organic carbon [DOC]) influence drivers of Hg bioaccumulation. Although prior studies have defined influences of biogeochemical variables on Hg production and bioaccumulation, it has been challenging to determine their influence across diverse habitats, regions, or biogeochemical conditions within a single study. We compared global (i.e., all sites), habitat-specific, and DOC-class models to illuminate how these controls on biotic Hg vary. Although the suite of important biogeochemical factors across all sites (e.g., aqueous Hg, DOC, sulfate [SO42-], and pH) was consistent with general findings in the literature, contrasting the restricted models revealed more nuanced controls on biosentinel Hg. Comparing habitats, aqueous (filtered) total mercury (THg) and SO42- were important in lentic systems whereas aqueous (filtered) methylmercury (MeHg), DOC, pH, and SO42- were important in lotic and wetland systems. The ability to identify important variables varied among habitats, with less certainty in lentic (model weight (W) = 0.05) than lotic (W = 0.11) or wetland habitats (W = 0.23), suggesting that biogeochemical drivers of bioaccumulation are more variable, or obscured by other aspects of Hg cycling, in these habitats. Results revealed a contrast in the importance of aqueous MeHg versus aqueous THg between DOC-classes: in low-DOC sites (<8.5 mg/L), availability of upstream inputs of MeHg appeared more important for bioaccumulation; in high-DOC sites (>8.5 mg/L) THg was more important, suggesting a link to in-situ controls on bioavailability of Hg for MeHg production. Mercury bioaccumulation (indicated by bioaccumulation factor) was more efficient in low DOC-class sites, likely due to reduced partitioning of aqueous MeHg to DOC. Together, findings highlight substantial variation in the drivers of Hg bioaccumulation and suggest consideration of these factors in natural resource management and decision-making.
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Affiliation(s)
- Sarah J Nelson
- Appalachian Mountain Club, Gorham, NH 03581, USA; University of Maine, School of Forest Resources, Orono, ME 04469, USA.
| | - James Willacker
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97330, USA
| | - Collin Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97330, USA
| | - Colleen Flanagan Pritz
- National Park Service, Air Resources Division, Natural Resource, Stewardship and Science Directorate, Lakewood, CO 80228, USA
| | | | - Amanda Klemmer
- School of Biology and Ecology, University of Maine, 5722 Deering Hall, Orono, ME 04469, USA
| | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, 1 Gifford Pinchot Dr., Madison, WI 53726, USA
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Hao Z, Zhao L, Liu J, Pu Q, Chen J, Meng B, Feng X. Relative importance of aceticlastic methanogens and hydrogenotrophic methanogens on mercury methylation and methylmercury demethylation in paddy soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167601. [PMID: 37832685 DOI: 10.1016/j.scitotenv.2023.167601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023]
Abstract
The accumulation of methylmercury (MeHg) in paddy soil results from a subtle balance between inorganic mercury (e.g., HgII) methylation and MeHg demethylation. Methanogens not only act as Hg methylators but may also facilitate MeHg demethylation. However, the diverse methanogen flora (e.g., aceticlastic and hydrogenotrophic types) that exists under ambient conditions has not previously been considered. Accordingly, the roles of different types of methanogens in HgII methylation and MeHg degradation in paddy soils were studied using the Hg isotope tracing technique combined with the application of methanogen inhibitors/stimulants. It was found that the response of HgII methylation to methanogen inhibitors or stimulants was site-dependent. Specifically, aceticlastic methanogens were suggested as the potential HgII methylators at the low Hg level background site, whereas hydrogenotrophic methanogens were potentially involved in MeHg production as Hg levels increased. In contrast, both aceticlastic and hydrogenotrophic methanogens facilitated MeHg degradation across the sampling sites. Additionally, competition between hydrogenotrophic and aceticlastic methanogens was observed in Hg-polluted paddy soils, implying that net MeHg production could be alleviated by promoting aceticlastic methanogens or inhibiting hydrogenotrophic methanogens. The findings gained from this study improve the understanding of the role of methanogens in net MeHg formation and link carbon turnover to Hg biogeochemistry in rice paddy ecosystems.
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Affiliation(s)
- Zhengdong Hao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Zhao
- School of Management Science, Guizhou University of Finance and Economics, Guiyang 550025, China; Guizhou Key Laboratory of Big Data Statistical Analysis (No. [2019]5103), Guiyang 550025, China.
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Ji Chen
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
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12
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Liu S, Hu R, Peng N, Zhou Z, Chen R, He Z, Wang C. Phylogenetic and ecophysiological novelty of subsurface mercury methylators in mangrove sediments. THE ISME JOURNAL 2023; 17:2313-2325. [PMID: 37880540 PMCID: PMC10689504 DOI: 10.1038/s41396-023-01544-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 10/12/2023] [Accepted: 10/13/2023] [Indexed: 10/27/2023]
Abstract
Mangrove sediment is a crucial component in the global mercury (Hg) cycling and acts as a hotspot for methylmercury (MeHg) production. Early evidence has documented the ubiquity of well-studied Hg methylators in mangrove superficial sediments; however, their diversity and metabolic adaptation in the more anoxic and highly reduced subsurface sediments are lacking. Through MeHg biogeochemical assay and metagenomic sequencing, we found that mangrove subsurface sediments (20-100 cm) showed a less hgcA gene abundance but higher diversity of Hg methylators than superficial sediments (0-20 cm). Regional-scale investigation of mangrove subsurface sediments spanning over 1500 km demonstrated a prevalence and family-level novelty of Hg-methylating microbial lineages (i.e., those affiliated to Anaerolineae, Phycisphaerae, and Desulfobacterales). We proposed the candidate phylum Zixibacteria lineage with sulfate-reducing capacity as a currently understudied Hg methylator across anoxic environments. Unlike other Hg methylators, the Zixibacteria lineage does not use the Wood-Ljungdahl pathway but has unique capabilities of performing methionine synthesis to donate methyl groups. The absence of cobalamin biosynthesis pathway suggests that this Hg-methylating lineage may depend on its syntrophic partners (i.e., Syntrophobacterales members) for energy in subsurface sediments. Our results expand the diversity of subsurface Hg methylators and uncover their unique ecophysiological adaptations in mangrove sediments.
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Affiliation(s)
- Songfeng Liu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Ruiwen Hu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Nenglong Peng
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Zhengyuan Zhou
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Ruihan Chen
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Zhili He
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Cheng Wang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China.
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13
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Kumar Chaudhary D, Bajagain R, Seo D, Hong Y, Han S. Depth-dependent microbial communities potentially mediating mercury methylation and various geochemical processes in anthropogenically affected sediments. ENVIRONMENTAL RESEARCH 2023; 237:116888. [PMID: 37586452 DOI: 10.1016/j.envres.2023.116888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 08/18/2023]
Abstract
Metal contamination and other geochemical alterations affect microbial composition and functional activities, disturbing natural biogeochemical cycles. Therefore, it is essential to understand the influences of multi-metal and geochemical interactions on microbial communities. This work investigated the distributions of total mercury (THg), methylmercury (MeHg), and trace metals in the anthropogenically affected sediment. The microbial communities and functional genes profiles were further determined to explore their association with Hg-methylation and geochemical features. The levels of THg and MeHg in sediment cores ranged between 10 and 40 mg/kg and 0.01-0.16 mg/kg, respectively, with an increasing trend toward bottom horizons. The major metals present at all depths were Al, Fe, Mn, and Zn. The enrichment and contamination indices confirmed that the trace metals were highly enriched in the anthropogenically affected sediment. Various functional genes were detected in all strata, indicating the presence of active microbial metabolic processes. The microbial community profiles revealed that the phyla Proteobacteria, Bacteroidetes, Bathyarchaeota, and Euryarchaeota, and the genera Thauera, Woeseia, Methanomethylovorans, and Methanosarcina were the dominant microbes. Correlating major taxa with geochemical variables inferred that sediment geochemistry substantially affects microbial community and biogeochemical cycles. Furthermore, archaeal methanogens and the bacterial phyla Chloroflexi and Firmicutes may play crucial roles in enhancing MeHg levels. Overall, these findings shed new light on the microbial communities potentially involved in Hg-methylation process and other biogeochemical cycles.
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Affiliation(s)
- Dhiraj Kumar Chaudhary
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, Republic of Korea
| | - Rishikesh Bajagain
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, Republic of Korea
| | - DongGyun Seo
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, Republic of Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, Republic of Korea.
| | - Seunghee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
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14
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Li Z, Wang T, Yang X, Wen X, Chen W, He Y, Yu Z, Zhang C. Microbial community function and methylmercury production in oxygen-limited paddy soil. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 266:115585. [PMID: 37856980 DOI: 10.1016/j.ecoenv.2023.115585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 10/03/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023]
Abstract
Methylmercury is a neurotoxic compound that can enter rice fields through rainfall or irrigation with contaminated wastewater, and then contaminate the human food chain through the consumption of rice. Flooded paddy soil has a porous structure that facilitates air exchange with the atmosphere, but the presence of trace amounts of oxygen in flooded rice field soil and its impact on microbial-mediated formation of methylmercury is still unclear. We compared the microbial communities and their functions in oxygen-depleted and oxygen-limited paddy soil. We discovered that oxygen-limited paddy soil had higher methylmercury concentration, which was strongly correlated with soil properties and methylation potential. Compared with oxygen-depleted soil, oxygen-limited soil altered the microbial composition based on 16 S rRNA sequences, but not based on hgcA sequences. Moreover, oxygen-limited soil enhanced microbial activity significantly, increasing the abundance of more than half of the KEGG pathways, especially the metabolic pathways that might be involved in methylation. Our study unveils how microbial communities influence methylmercury formation in oxygen-limited paddy soil. ENVIRONMENTAL IMPLICATIONS: This study examined how low oxygen input affects microbial-induced MeHg formation in anaerobic paddy soil. We found that oxygen-limited soil produced more MeHg than oxygen-depleted soil. Oxygen input altered the microbial community structure of 16 S rRNA sequencing in anaerobic paddy soil, but had little impact on the hgcA sequencing community structure. Microbial activity and metabolic functions related to MeHg formation were also higher in oxygen-limited paddy soil. We suggest that oxygen may not be a limiting factor for Hg methylators, and that insufficient oxygen input in flooded paddy soil increases the risk of human exposure to MeHg from rice consumption.
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Affiliation(s)
- Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zhigang Yu
- Australian Center for Water and Environmental Biotechnology, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
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15
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Gao Y, Cheng H, Xiong B, Du H, Liu L, Imanaka T, Igarashi Y, Ma M, Wang D, Luo F. Biogeochemical transformation of mercury driven by microbes involved in anaerobic digestion of municipal wastewater. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 344:118640. [PMID: 37478720 DOI: 10.1016/j.jenvman.2023.118640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/25/2023] [Accepted: 07/15/2023] [Indexed: 07/23/2023]
Abstract
Anaerobic digestion (AD) with municipal wastewater contained heavy metal mercury (Hg) highly affects the utilization of activated sludge, and poses severe threat to the health of human beings. However, the biogeochemical transformation of Hg during AD remains unclear. Here, we investigated the biogeochemical transformation and environmental characteristics of Hg and the variations of dominant microbes during AD. The results showed that Hg(II) methylation is dominant in the early stage of AD, while methylmercury (MeHg) demethylation dominates in the later stage. Dissolved total Hg (DTHg) in the effluent sludge decreased with time, while THg levels enhanced to varying degrees at the final stage. Sulfate significant inhibits MeHg formation, reduces bioavailability of Hg(II) by microbes and thus inhibits Hg(II) methylation. Microbial community analysis reveals that strains in Methanosarcina and Aminobacterium from the class of Methanomicrobia, rather than Deltaproteobacteria, may be directly related to Hg(II) methylation and MeHg demethylation. Overall, this research provide insights into the biogeochemical transformation of Hg in the anaerobic digestion of municipal wastewater treatment. This work is beneficial for scientific treatment of municipal wastewater and effluent sludge, thus reducing the risk of MeHg to human beings.
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Affiliation(s)
- Yuanqin Gao
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Hao Cheng
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Bingcai Xiong
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Hongxia Du
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China.
| | - Lei Liu
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Tadayuki Imanaka
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Yasuo Igarashi
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Ming Ma
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China; Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, 400715, PR China.
| | - Dinyong Wang
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
| | - Feng Luo
- Chongqing Key Laboratory of Biogenetics and Anaerobic Microecology, College of Resources and Environment, Southwest University, Chongqing, 400715, PR China
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16
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Peterson BD, Poulin BA, Krabbenhoft DP, Tate MT, Baldwin AK, Naymik J, Gastelecutto N, McMahon KD. Metabolically diverse microorganisms mediate methylmercury formation under nitrate-reducing conditions in a dynamic hydroelectric reservoir. THE ISME JOURNAL 2023; 17:1705-1718. [PMID: 37495676 PMCID: PMC10504345 DOI: 10.1038/s41396-023-01482-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/28/2023]
Abstract
Brownlee Reservoir is a mercury (Hg)-impaired hydroelectric reservoir that exhibits dynamic hydrological and geochemical conditions and is located within the Hells Canyon Complex in Idaho, USA. Methylmercury (MeHg) contamination in fish is a concern in the reservoir. While MeHg production has historically been attributed to sulfate-reducing bacteria and methanogenic archaea, microorganisms carrying the hgcA gene are taxonomically and metabolically diverse and the major biogeochemical cycles driving mercury (Hg) methylation are not well understood. In this study, Hg speciation and redox-active compounds were measured throughout Brownlee Reservoir across the stratified period in four consecutive years (2016-2019) to identify the location where and redox conditions under which MeHg is produced. Metagenomic sequencing was performed on a subset of samples to characterize the microbial community with hgcA and identify possible links between biogeochemical cycles and MeHg production. Biogeochemical profiles suggested in situ water column Hg methylation was the major source of MeHg. These profiles, combined with genome-resolved metagenomics focused on hgcA-carrying microbes, indicated that MeHg production occurs in this system under nitrate- or manganese-reducing conditions, which were previously thought to preclude Hg-methylation. Using this multidisciplinary approach, we identified the cascading effects of interannual variability in hydrology on the redox status, microbial metabolic strategies, abundance and metabolic diversity of Hg methylators, and ultimately MeHg concentrations throughout the reservoir. This work expands the known conditions conducive to producing MeHg and suggests that the Hg-methylation mitigation efforts by nitrate or manganese amendment may be unsuccessful in some locations.
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Affiliation(s)
- Benjamin D Peterson
- Department of Civil and Environmental Engineering, University of Wisconsin - Madison, Madison, WI, 53706, USA.
- Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, 53706, USA.
- Department of Environmental Toxicology, University of California - Davis, Davis, CA, 95616, USA.
| | - Brett A Poulin
- Department of Environmental Toxicology, University of California - Davis, Davis, CA, 95616, USA
| | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, Madison, WI, 53726, USA
| | - Michael T Tate
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, Madison, WI, 53726, USA
| | - Austin K Baldwin
- U.S. Geological Survey, Idaho Water Science Center, Boise, ID, 83702, USA
| | | | | | - Katherine D McMahon
- Department of Civil and Environmental Engineering, University of Wisconsin - Madison, Madison, WI, 53706, USA
- Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, 53706, USA
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17
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Cabrol L, Capo E, van Vliet DM, von Meijenfeldt FAB, Bertilsson S, Villanueva L, Sánchez-Andrea I, Björn E, G. Bravo A, Heimburger Boavida LE. Redox gradient shapes the abundance and diversity of mercury-methylating microorganisms along the water column of the Black Sea. mSystems 2023; 8:e0053723. [PMID: 37578240 PMCID: PMC10469668 DOI: 10.1128/msystems.00537-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 06/16/2023] [Indexed: 08/15/2023] Open
Abstract
In the global context of seawater deoxygenation triggered by climate change and anthropogenic activities, changes in redox gradients impacting biogeochemical transformations of pollutants, such as mercury, become more likely. Being the largest anoxic basin worldwide, with high concentrations of the potent neurotoxic methylmercury (MeHg), the Black Sea is an ideal natural laboratory to provide new insights about the link between dissolved oxygen concentration and hgcAB gene-carrying (hgc+) microorganisms involved in the formation of MeHg. We combined geochemical and microbial approaches to assess the effect of vertical redox gradients on abundance, diversity, and metabolic potential of hgc+ microorganisms in the Black Sea water column. The abundance of hgcA genes [congruently estimated by quantitative PCR (qPCR) and metagenomics] correlated with MeHg concentration, both maximal in the upper part of the anoxic water. Besides the predominant Desulfobacterales, hgc+ microorganisms belonged to a unique assemblage of diverse-previously underappreciated-anaerobic fermenters from Anaerolineales, Phycisphaerae (characteristic of the anoxic and sulfidic zone), Kiritimatiellales, and Bacteroidales (characteristic of the suboxic zone). The metabolic versatility of Desulfobacterota differed from strict sulfate reduction in the anoxic water to reduction of various electron acceptors in the suboxic water. Linking microbial activity and contaminant concentration in environmental studies is rare due to the complexity of biological pathways. In this study, we disentangle the role of oxygen in shaping the distribution of Hg-methylating microorganisms consistently with MeHg concentration, and we highlight their taxonomic and metabolic niche partitioning across redox gradients, improving the prediction of the response of marine communities to the expansion of oxygen-deficient zones. IMPORTANCE Methylmercury (MeHg) is a neurotoxin detected at high concentrations in certain marine ecosystems, posing a threat to human health. MeHg production is mainly mediated by hgcAB gene-carrying (hgc+) microorganisms. Oxygen is one of the main factors controlling Hg methylation; however, its effect on the diversity and ecology of hgc+ microorganisms remains unknown. Under the current context of seawater deoxygenation, mercury cycling is expected to be disturbed. Here, we show the strong effect of oxygen gradients on the distribution of potential Hg methylators. In addition, we show for the first time the significant contribution of a unique assemblage of potential fermenters from Anaerolineales, Phycisphaerae, and Kiritimatiellales to Hg methylation, stratified in different redox niches along the Black Sea gradient. Our results considerably expand the known taxonomic diversity and ecological niches prone to the formation of MeHg and contribute to better apprehend the consequences of oxygen depletion in seawater.
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Affiliation(s)
- Léa Cabrol
- Aix Marseille University, Univ. Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, Marseille, France
- Institute of Ecology and Biodiversity (IEB), University of Chile, Santiago, Chile
| | - Eric Capo
- Department of Marine Biology and Oceanography, Institute of Marine Sciences, CSIC, Barcelona, Spain
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Daan M. van Vliet
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, the Netherlands
- Wageningen Food and Biobased Research, Wageningen, the Netherlands
| | - F. A. Bastiaan von Meijenfeldt
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Texel, the Netherlands
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Laura Villanueva
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Texel, the Netherlands
- Faculty of Geosciences, Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands
| | - Irene Sánchez-Andrea
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, the Netherlands
| | - Erik Björn
- Department of Chemistry, Umeå University, Umeå, Sweden
| | - Andrea G. Bravo
- Department of Marine Biology and Oceanography, Institute of Marine Sciences, CSIC, Barcelona, Spain
| | - Lars-Eric Heimburger Boavida
- Aix Marseille University, Univ. Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, Marseille, France
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18
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Diverse Methylmercury (MeHg) Producers and Degraders Inhabit Acid Mine Drainage Sediments, but Few Taxa Correlate with MeHg Accumulation. mSystems 2023; 8:e0073622. [PMID: 36507660 PMCID: PMC9948709 DOI: 10.1128/msystems.00736-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Methylmercury (MeHg) is a notorious neurotoxin, and its production and degradation in the environment are mainly driven by microorganisms. A variety of microbial MeHg producers carrying the gene pair hgcAB and degraders carrying the merB gene have been separately reported in recent studies. However, surprisingly little attention has been paid to the simultaneous investigation of the diversities of microbial MeHg producers and degraders in a given habitat, and no studies have been performed to explore to what extent these two contrasting microbial groups correlate with MeHg accumulation in the habitat of interest. Here, we collected 86 acid mine drainage (AMD) sediments from an area spanning approximately 500,000 km2 in southern China and profiled the sediment-borne putative MeHg producers and degraders using genome-resolved metagenomics. 46 metagenome-assembled genomes (MAGs) containing hgcAB and 93 MAGs containing merB were obtained, including those from various taxa without previously known MeHg-metabolizing microorganisms. These diverse MeHg-metabolizing MAGs were formed largely via multiple independent horizontal gene transfer (HGT) events. The putative MeHg producers from Deltaproteobacteria and Firmicutes as well as MeHg degraders from Acidithiobacillia were closely correlated with MeHg accumulation in the sediments. Furthermore, these three taxa, in combination with two abiotic factors, explained over 60% of the variance in MeHg accumulation. Most of the members of these taxa were characterized by their metabolic potential for nitrogen fixation and copper tolerance. Overall, these findings improve our understanding of the ecology of MeHg-metabolizing microorganisms and likely have implications for the development of management strategies for the reduction of MeHg accumulation in the AMD sediments. IMPORTANCE Microorganisms are the main drivers of MeHg production and degradation in the environment. However, little attention has been paid to the simultaneous investigation of the diversities of microbial MeHg producers and degraders in a given habitat. We used genome-resolved metagenomics to reveal the vast phylogenetic and metabolic diversities of putative MeHg producers and degraders in AMD sediments. Our results show that the diversity of MeHg-metabolizing microorganisms (particularly MeHg degraders) in AMD sediments is much higher than was previously recognized. Via multiple linear regression analysis, we identified both microbial and abiotic factors affecting MeHg accumulation in AMD sediments. Despite their great diversity, only a few taxa of MeHg-metabolizing microorganisms were closely correlated with MeHg accumulation. This work underscores the importance of using genome-resolved metagenomics to survey MeHg-metabolizing microorganisms and provides a framework for the illumination of the microbial basis of MeHg accumulation via the characterization of physicochemical properties, MeHg-metabolizing microorganisms, and the correlations between them.
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19
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Hu H, Gao Y, Yu H, Xiao H, Chen S, Tan W, Tang J, Xi B. Mechanisms and biological effects of organic amendments on mercury speciation in soil-rice systems: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 251:114516. [PMID: 36628877 DOI: 10.1016/j.ecoenv.2023.114516] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and biomagnification effects. As the largest global Hg reservoir, the Hg cumulatively stored in soils has reached as high as 250-1000 Gg. Even more concerning is that global soil-rice systems distributed in many countries have become central to the global Hg cycle because they are both a major food source for more than 3 billion people worldwide and the central bridge linking atmospheric and soil Hg circulation. In this review, we discuss the form distribution, transformation, and bioavailability of Hg in soil-rice systems by focusing on the Hg methylation and demethylation pathways and distribution, uptake, and accumulation in rice plants and the effects of Hg on the community structure and ecological functions of microorganisms in soil-rice systems. In addition, we clarify the mechanisms through which commonly used humus and biochar organic amendments influence Hg and its environmental effects in soil-rice systems. The review also elaborates on the advantages of sulfur-modified biochars and their critical role in controlling Hg migration and bioavailability in soils. Finally, we provide key information about Hg pollution in soil-rice systems, which is of great significance for developing appropriate strategies and mitigation planning to limit Hg bioconcentration in rice crops and achieving key global sustainable development goals, such as the guarantee of food security and the promotion of sustainable agriculture.
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Affiliation(s)
- Hualing Hu
- Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Yiman Gao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Hanxia Yu
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Haoyan Xiao
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Shuhe Chen
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Wenbing Tan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Jun Tang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Beidou Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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20
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Barrouilhet S, Monperrus M, Tessier E, Khalfaoui-Hassani B, Guyoneaud R, Isaure MP, Goñi-Urriza M. Effect of exogenous and endogenous sulfide on the production and the export of methylmercury by sulfate-reducing bacteria. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:3835-3846. [PMID: 35953752 DOI: 10.1007/s11356-022-22173-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 07/19/2022] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) is a global pollutant of environmental and health concern; its methylated form, methylmercury (MeHg), is a potent neurotoxin. Sulfur-containing molecules play a role in MeHg production by microorganisms. While sulfides are considered to limit Hg methylation, sulfate and cysteine were shown to favor this process. However, these two forms can be endogenously converted by microorganisms into sulfide. Here, we explore the effect of sulfide (produced by the cell or supplied exogenously) on Hg methylation. For this purpose, Pseudodesulfovibrio hydrargyri BerOc1 was cultivated in non-sulfidogenic conditions with addition of cysteine and sulfide as well as in sulfidogenic conditions. We report that Hg methylation depends on sulfide concentration in the culture and the sulfides produced by cysteine degradation or sulfate reduction could affect the Hg methylation pattern. Hg methylation was independent of hgcA expression. Interestingly, MeHg production was maximal at 0.1-0.5 mM of sulfides. Besides, a strong positive correlation between MeHg in the extracellular medium and the increase of sulfide concentrations was observed, suggesting a facilitated MeHg export with sulfide and/or higher desorption from the cell. We suggest that sulfides (exogenous or endogenous) play a key role in controlling mercury methylation and should be considered when investigating the impact of Hg in natural environments.
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Affiliation(s)
- Sophie Barrouilhet
- Universite de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IPREM UMR 5254, Pau, France
| | - Mathilde Monperrus
- Universite de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IPREM UMR 5254, Anglet, France
| | - Emmanuel Tessier
- Universite de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IPREM UMR 5254, Pau, France
| | | | - Rémy Guyoneaud
- Universite de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IPREM UMR 5254, Pau, France
| | - Marie-Pierre Isaure
- Universite de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IPREM UMR 5254, Pau, France
| | - Marisol Goñi-Urriza
- Universite de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IPREM UMR 5254, Pau, France.
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21
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McCarter CPR, Sebestyen SD, Coleman Wasik JK, Engstrom DR, Kolka RK, Jeremiason JD, Swain EB, Monson BA, Branfireun BA, Balogh SJ, Nater EA, Eggert SL, Ning P, Mitchell CPJ. Long-Term Experimental Manipulation of Atmospheric Sulfate Deposition to a Peatland: Response of Methylmercury and Related Solute Export in Streamwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:17615-17625. [PMID: 36445185 DOI: 10.1021/acs.est.2c02621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Changes in sulfate (SO42-) deposition have been linked to changes in mercury (Hg) methylation in peatlands and water quality in freshwater catchments. There is little empirical evidence, however, of how quickly methyl-Hg (MeHg, a bioaccumulative neurotoxin) export from catchments might change with declining SO42- deposition. Here, we present responses in total Hg (THg), MeHg, total organic carbon, pH, and SO42- export from a peatland-dominated catchment as a function of changing SO42- deposition in a long-term (1998-2011), whole-ecosystem, control-impact experiment. Annual SO42- deposition to half of a 2-ha peatland was experimentally increased 6-fold over natural levels and then returned to ambient levels in two phases. Sulfate additions led to a 5-fold increase in monthly flow-weighted MeHg concentrations and yields relative to a reference catchment. Once SO42- additions ceased, MeHg concentrations in the outflow streamwater returned to pre-SO42- addition levels within 2 years. The decline in streamwater MeHg was proportional to the change in the peatland area no longer receiving experimental SO42- inputs. Importantly, net demethylation and increased sorption to peat hastened the return of MeHg to baseline levels beyond purely hydrological flushing. Overall, we present clear empirical evidence of rapid and proportionate declines in MeHg export from a peatland-dominated catchment when SO42- deposition declines.
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Affiliation(s)
- Colin P R McCarter
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, OntarioM1C 1A4, Canada
| | - Stephen D Sebestyen
- USDA Forest Service Northern Research Station, Grand Rapids, Minnesota55744, United States
| | - Jill K Coleman Wasik
- Department of Plant and Earth Science, University of Wisconsin - River Falls, 410 S. 3rd Street, River Falls, Wisconsin54022, United States
| | - Daniel R Engstrom
- St. Croix Watershed Research Station, Science Museum of Minnesota, 16910 152nd Street N., Marine on St. Croix, Minnesota55047, United States
| | - Randall K Kolka
- USDA Forest Service Northern Research Station, Grand Rapids, Minnesota55744, United States
| | - Jeff D Jeremiason
- Department of Chemistry, Gustavus Adolphus College, 800 W College AvenueSt. Peter, Minnesota56082, United States
| | - Edward B Swain
- Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, Minnesota55108, United States
| | - Bruce A Monson
- Minnesota Pollution Control Agency, 520 Lafayette Road North, Saint Paul, Minnesota55155, United States
| | - Brian A Branfireun
- Department of Biology, The University of Western Ontario, London, OntarioN5B 2A7, Canada
| | - Steven J Balogh
- Metropolitan Council Environmental Services, 2400 Childs Road, Saint Paul, Minnesota55106, United States
| | - Edward A Nater
- Department of Soil, Water, and Climate, University of Minnesota, St. Paul, Minnesota55108, United States
| | - Susan L Eggert
- USDA Forest Service Northern Research Station, Grand Rapids, Minnesota55744, United States
| | - Paris Ning
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, OntarioM1C 1A4, Canada
| | - Carl P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, OntarioM1C 1A4, Canada
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22
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Casso-Hartmann L, Rojas-Lamos P, McCourt K, Vélez-Torres I, Barba-Ho LE, Bolaños BW, Montes CL, Mosquera J, Vanegas D. Water pollution and environmental policy in artisanal gold mining frontiers: The case of La Toma, Colombia. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:158417. [PMID: 36055504 DOI: 10.1016/j.scitotenv.2022.158417] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
Artisanal and small-scale gold mining (ASGM) is the largest anthropogenic source of mercury emissions globally. Concern over mercury pollution increases due to its long-term impacts on human health and aquatic and terrestrial ecosystems. Using a participatory research methodology, we gathered social and behavioral information regarding daily practices and water usage by an ASGM community in Suárez, Colombia. Based on this information, we identified 18 sampling sites of water sources commonly used by the community. The samples were analyzed for total mercury, total coliforms, pH, electrical conductivity, and total dissolved oxygen. Physicochemical and microbiological parameters from the water assessment were compared with the drinking water thresholds set by the Colombian regulatory agencies, the EPA, and the WHO. Our results showed that the majority of the samples do not meet one or more quality and safety standards. On average, the sampling sites showed total mercury levels below the regulatory limits; however, the data had considerable variability, and in many cases, individual observations fell above the maximum concentration limit for drinking water. We discuss these results within the larger framework of the regulatory gaps for human and environmental protection in ASGM contexts. The total lack of water, sanitation, and hygiene infrastructure, combined with the long-term consumption of sublethal doses of mercury and other water contaminants, constitutes a significant threat to the well-being of communities and territories that necessitates further research and intervention by institutional authorities.
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Affiliation(s)
- Lisseth Casso-Hartmann
- Clemson University, Department of Environmental Engineering and Earth Sciences, United States of America; Interdisciplinary Group for Biotechnological Innovation and Ecosocial Change - BioNovo, Universidad del Valle, Colombia
| | - Paulina Rojas-Lamos
- Universidad del Valle, Facultad de Ingeniería, Escuela de Recursos Naturales y del Ambiente, Calle 13 no. 100-00, Cali, Colombia; Interdisciplinary Group for Biotechnological Innovation and Ecosocial Change - BioNovo, Universidad del Valle, Colombia
| | - Kelli McCourt
- Clemson University, Department of Environmental Engineering and Earth Sciences, United States of America; Global Alliance for Rapid Diagnostics -GARD, Michigan State University, United States of America
| | - Irene Vélez-Torres
- Universidad del Valle, Facultad de Ingeniería, Escuela de Recursos Naturales y del Ambiente, Calle 13 no. 100-00, Cali, Colombia; Interdisciplinary Group for Biotechnological Innovation and Ecosocial Change - BioNovo, Universidad del Valle, Colombia
| | - Luz Edith Barba-Ho
- Universidad del Valle, Facultad de Ingeniería, Escuela de Recursos Naturales y del Ambiente, Calle 13 no. 100-00, Cali, Colombia
| | - Byron Wladimir Bolaños
- Universidad del Valle, Facultad de Ingeniería, Escuela de Recursos Naturales y del Ambiente, Calle 13 no. 100-00, Cali, Colombia
| | - Claudia Lorena Montes
- Universidad del Valle, Facultad de Ingeniería, Escuela de Estadística, Calle 13 no. 100-00, Cali, Colombia
| | - Jaime Mosquera
- Universidad del Valle, Facultad de Ingeniería, Escuela de Estadística, Calle 13 no. 100-00, Cali, Colombia
| | - Diana Vanegas
- Clemson University, Department of Environmental Engineering and Earth Sciences, United States of America; Interdisciplinary Group for Biotechnological Innovation and Ecosocial Change - BioNovo, Universidad del Valle, Colombia; Global Alliance for Rapid Diagnostics -GARD, Michigan State University, United States of America.
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23
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Jonsson S, Mastromonaco MN, Wang F, Bravo AG, Cairns WRL, Chételat J, Douglas TA, Lescord G, Ukonmaanaho L, Heimbürger-Boavida LE. Arctic methylmercury cycling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 850:157445. [PMID: 35882324 DOI: 10.1016/j.scitotenv.2022.157445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Anthropogenic mercury (Hg) undergoes long-range transport to the Arctic where some of it is transformed into methylmercury (MeHg), potentially leading to high exposure in some Arctic inhabitants and wildlife. The environmental exposure of Hg is determined not just by the amount of Hg entering the Arctic, but also by biogeochemical and ecological processes occurring in the Arctic. These processes affect MeHg uptake in biota by regulating the bioavailability, methylation and demethylation, bioaccumulation and biomagnification of MeHg in Arctic ecosystems. Here, we present a new budget for pools and fluxes of MeHg in the Arctic and review the scientific advances made in the last decade on processes leading to environmental exposure to Hg. Methylation and demethylation are key processes controlling the pool of MeHg available for bioaccumulation. Methylation of Hg occurs in diverse Arctic environments including permafrost, sediments and the ocean water column, and is primarily a process carried out by microorganisms. While microorganisms carrying the hgcAB gene pair (responsible for Hg methylation) have been identified in Arctic soils and thawing permafrost, the formation pathway of MeHg in oxic marine waters remains less clear. Hotspots for methylation of Hg in terrestrial environments include thermokarst wetlands, ponds and lakes. The shallow sub-surface enrichment of MeHg in the Arctic Ocean, in comparison to other marine systems, is a possible explanation for high MeHg concentrations in some Arctic biota. Bioconcentration of aqueous MeHg in bacteria and algae is a critical step in the transfer of Hg to top predators, which may be dampened or enhanced by the presence of organic matter. Variable trophic position has an important influence on MeHg concentrations among populations of top predator species such as ringed seal and polar bears distributed across the circumpolar Arctic. These scientific advances highlight key processes that affect the fate of anthropogenic Hg deposited to Arctic environments.
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Affiliation(s)
- Sofi Jonsson
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden.
| | | | - Feiyue Wang
- Centre for Earth Observation Science, and Department of Environment and Geography, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
| | - Warren R L Cairns
- CNR Institute of Polar Sciences and Ca' Foscari University, Venice, Italy
| | - John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, ON, Canada
| | - Thomas A Douglas
- U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK, USA
| | - Gretchen Lescord
- Wildlife Conservation Society Canada and Laurentian University, Vale Living with Lakes Center, Sudbury, Ontario, Canada
| | - Liisa Ukonmaanaho
- Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00791 Helsinki, Finland
| | - Lars-Eric Heimbürger-Boavida
- CNRS/INSU,Aix Marseille Université,Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO), Marseille, France
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24
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Chaudhary DK, Karki HP, Bajagain R, Kim H, Rhee TS, Hong JK, Han S, Choi YG, Hong Y. Mercury and other trace elements distribution and profiling of microbial community in the surface sediments of East Siberian Sea. MARINE POLLUTION BULLETIN 2022; 185:114319. [PMID: 36343547 DOI: 10.1016/j.marpolbul.2022.114319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
In this study, total mercury (THg), methylmercury (MeHg), various trace elements, and microbial communities were measured in surface sediments of the East Siberian Sea (ESS). The results showed that the average values of THg and MeHg were 58.8 ± 15.21 μg/kg and 0.50 ± 0.22 μg/kg, respectively. The notable levels of trace elements present in both surface sediment and porewater were Al, Fe, and Mn. The enrichment factor and geoaccumulation index analyses found that both natural phenomena and anthropogenic activities contributed to elevated concentrations of metals in the ESS. The redox proxy metals, pH, and SO42- were the major factors influencing the THg and MeHg distributions. Microbial profiles were substantially affected by metals and other abiotic factors. Proteobacteria and Thaumarchaeota were the most abundant phyla. Overall, the findings presented here facilitate the understanding of the current status of metal contamination, its influencing factors, and metal-microbiota-interactions in ESS.
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Affiliation(s)
- Dhiraj Kumar Chaudhary
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea
| | - Hem Prakash Karki
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea
| | - Rishikesh Bajagain
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea
| | - Hwansuk Kim
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea
| | - Tae Siek Rhee
- Korea Polar Research Institute, 26 Songdomirae-ro, Incheon 21990, Republic of Korea
| | - Jong Kuk Hong
- Korea Polar Research Institute, 26 Songdomirae-ro, Incheon 21990, Republic of Korea
| | - Seunghee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Young-Gyun Choi
- Department of Environmental Engineering, Chungnam National University, Daejeon City, Republic of Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City 30019, Republic of Korea.
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25
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Frey B, Rast BM, Qi W, Stierli B, Brunner I. Long-term mercury contamination does not affect the microbial gene potential for C and N cycling in soils but enhances detoxification gene abundance. Front Microbiol 2022; 13:1034138. [PMID: 36274742 PMCID: PMC9581213 DOI: 10.3389/fmicb.2022.1034138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Soil microorganisms are key transformers of mercury (Hg), a toxic and widespread pollutant. It remains uncertain, however, how long-term exposure to Hg affects crucial microbial functions, such as litter decomposition and nitrogen cycling. Here, we used a metagenomic approach to investigate the state of soil functions in an agricultural floodplain contaminated with Hg for more than 80 years. We sampled soils along a gradient of Hg contamination (high, moderate, low). Hg concentrations at the highly contaminated site (36 mg kg–1 dry soil on average) were approximately 10 times higher than at the moderately contaminated site (3 mg kg–1 dry soil) and more than 100 times higher than at the site with low contamination (0.25 mg kg–1 dry soil; corresponding to the natural background concentration in Switzerland). The analysis of the CAZy and NCyc databases showed that carbon and nitrogen cycling was not strongly affected with high Hg concentrations, although a significant change in the beta-diversity of the predicted genes was observed. The only functional classes from the CAZy database that were significantly positively overrepresented under higher Hg concentrations were genes involved in pectin degradation, and from the NCyc database dissimilatory nitrate reduction and N-fixation. When comparing between low and high Hg concentrations the genes of the EggNOG functional category of inorganic ion transport and metabolism, two genes encoding Hg transport proteins and one gene involved in heavy metal transport detoxification were among those that were highly significantly overrepresented. A look at genes specifically involved in detoxification of Hg species, such as the mer and hgc genes, showed a significant overrepresentation when Hg contamination was increased. Normalized counts of these genes revealed a dominant role for the phylum Proteobacteria. In particular, most counts for almost all mer genes were found in Betaproteobacteria. In contrast, hgc genes were most abundant in Desulfuromonadales. Overall, we conclude from this metagenomic analysis that long-term exposure to high Hg triggers shifts in the functional beta-diversity of the predicted microbial genes, but we do not see a dramatic change or breakdown in functional capabilities, but rather functional redundancy.
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Affiliation(s)
- Beat Frey
- Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
- *Correspondence: Beat Frey,
| | - Basil M. Rast
- Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Weihong Qi
- FGCZ Functional Genomics Center Zurich, ETH Zürich and University of Zürich, Zürich, Switzerland
- SIB Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Beat Stierli
- Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Ivano Brunner
- Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
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26
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Schwartz GE, Muller KA, Rathore SS, Wilpiszeski RL, Carrell AA, Cregger MA, Elias DA, Podar M, Painter SL, Brooks SC. Incorporating concentration-dependent sediment microbial activity into methylmercury production kinetics modeling. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:1392-1405. [PMID: 34727150 DOI: 10.1039/d1em00287b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In anoxic environments, anaerobic microorganisms carrying the hgcAB gene cluster can mediate the transformation of inorganic mercury (Hg(II)) to monomethylmercury (MMHg). The kinetics of Hg(II) transformation to MMHg in periphyton from East Fork Poplar Creek (EFPC) in Oak Ridge, TN have previously been modeled using a transient availability model (TAM). The TAM for Hg(II) methylation combines methylation/demethylation kinetics with kinetic expressions for processes that decrease Hg(II) and MMHg availability for methylation and demethylation (multisite sorption of Hg(II) and MMHg, Hg(II) reduction/Hg(0) oxidation). In this study, the TAM is used for the first time to describe MMHg production in sediment. We assessed MMHg production in sediment microcosms using two different sediment types from EFPC: a relatively anoxic, carbon-rich sediment with higher microbial activity (higher CO2 production from sediment) and a relatively oxic, sandy, carbon-poor sediment with lower microbial activity (lower CO2 production from sediment). Based on 16s rRNA sequencing, the overall microbial community structure in the two sediments was retained during the incubations. However, the hgcA containing methanogenic Euryarchaeota communities differed between sediment types and their growth followed different trajectories over the course of incubations, potentially contributing to the distinct patterns of MMHg production observed. The general TAM paradigm performed well in describing MMHg production in the sediments. However, the MMHg production and ancillary data suggested the need to revise the model structure to incorporate terms for concentration-dependent microbial activity over the course of the incubations. We modified the TAM to include Monod-type kinetics for methylation and demethylation and observed an improved fit for the carbon-rich, microbially active sediment. Overall our work shows that the TAM can be applied to describe Hg(II) methylation in sediments and that including expressions accounting for concentration-dependent microbial activity can improve the accuracy of the model description of the data in some cases.
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Affiliation(s)
- Grace E Schwartz
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| | - Katherine A Muller
- Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Saubhagya S Rathore
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| | - Regina L Wilpiszeski
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Alyssa A Carrell
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Melissa A Cregger
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA
| | - Scott L Painter
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, P. O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA.
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27
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Brunet F, Tisserand D, Lanson M, Malvoisin B, Bertrand M, Bonnaud C. Real-time monitoring of aqueous Hg 2+ reduction dynamics by magnetite/iron metal composite powders synthesized hydrothermally. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 86:596-609. [PMID: 35960839 DOI: 10.2166/wst.2022.210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
An iron-based powder material composed of zerovalent iron (8 wt.%) and magnetite (92 wt.%), has been synthesized hydrothermally at 200 °C from zero-valent iron. Its effect on the reduction of aqueous Hg2+ into gaseous Hg0 has been investigated at ambient conditions for pH comprised between 4 and 8.5. The production of Hg0 was monitored with an online mercury vapor analyzer at the picogram level for concentrations of iron-based composite of a few tenths of mg L-1. Starting from a solution having an Hg2+ concentration of 25 ng L-1 at pH = 4, a succession of two Hg0 production events was recorded. The first event is related to the Hg2+ reduction by ZVI which fully dissolved within the first hours. Upon ZVI consumption, pH drifted towards the pH window where magnetite can efficiently reduce Hg2+ at the hour timescale, resulting in a second Hg0 production peak. The combined use of ZVI and magnetite to remove aqueous Hg2+ by formation of Hg0 (volatile) under mild acidic pH allows (1) to maximize the Hg2+ reduction rate and (2) to take benefit of the longer lifetime of magnetite compared to ZVI.
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Affiliation(s)
- Fabrice Brunet
- ISTERRE, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, Grenoble 38000, France E-mail:
| | - Delphine Tisserand
- ISTERRE, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, Grenoble 38000, France E-mail:
| | - Martine Lanson
- ISTERRE, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, Grenoble 38000, France E-mail:
| | - Benjamin Malvoisin
- ISTERRE, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, Grenoble 38000, France E-mail:
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28
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Huang H, Mangal V, Rennie MD, Tong H, Simpson MJ, Mitchell CPJ. Mercury methylation and methylmercury demethylation in boreal lake sediment with legacy sulphate pollution. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:932-944. [PMID: 35532885 DOI: 10.1039/d2em00064d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Sulphate and dissolved organic matter (DOM) in freshwater systems may regulate the formation of methylmercury (MeHg), a potent neurotoxin that biomagnifies in aquatic ecosystems. While many boreal lakes continue to recover from decades of elevated atmospheric sulphate deposition, little research has examined whether historically high sulphate concentrations can result in persistently elevated MeHg production and accumulation in aquatic systems. This study used sediment from a historically sulphate-impacted lake and an adjacent reference lake in northwestern Ontario, Canada to investigate the legacy effects of sulphate pollution, as well as the effects of newly added sulphate, natural organic matter (NOM) of varying sulphur content and a sulphate reducing bacteria (SRB) inhibitor on enhancing or inhibiting the Hg methylation and demethylation activity (Kmeth and Kdemeth) in the sediment. We found that Kmeth and MeHg concentrations in sulphate-impacted lake sediment were significantly greater than in reference lake sediment. Further adding sulphate or NOM with different sulphur content to sediment of both lakes did not significantly change Kmeth. The addition of a SRB inhibitor resulted in lower Kmeth only in sulphate-impacted sediment, but methylation was not entirely depressed. Methylmercury demethylation potentials in sediment were consistent across lakes and experimental treatments, except for some impacts related to SRB inhibitor additions in the reference lake sediment. Overall, a broader community of microbes beyond SRB may be methylating Hg and demethylating MeHg in this system. This study reveals that legacies of sulphate pollution in boreal lakes may persist for decades in stimulating elevated Hg methylation in sediment.
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Affiliation(s)
- Haiyong Huang
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Ontario, Canada.
| | - Vaughn Mangal
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Ontario, Canada.
| | - Michael D Rennie
- Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada
| | - Huan Tong
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Ontario, Canada.
- Environmental NMR Centre, University of Toronto Scarborough, Ontario, Canada
| | - Myrna J Simpson
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Ontario, Canada.
- Environmental NMR Centre, University of Toronto Scarborough, Ontario, Canada
| | - Carl P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Ontario, Canada.
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Chételat J, McKinney MA, Amyot M, Dastoor A, Douglas TA, Heimbürger-Boavida LE, Kirk J, Kahilainen KK, Outridge PM, Pelletier N, Skov H, St Pierre K, Vuorenmaa J, Wang F. Climate change and mercury in the Arctic: Abiotic interactions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 824:153715. [PMID: 35149079 DOI: 10.1016/j.scitotenv.2022.153715] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 06/14/2023]
Abstract
Dramatic environmental shifts are occuring throughout the Arctic from climate change, with consequences for the cycling of mercury (Hg). This review summarizes the latest science on how climate change is influencing Hg transport and biogeochemical cycling in Arctic terrestrial, freshwater and marine ecosystems. As environmental changes in the Arctic continue to accelerate, a clearer picture is emerging of the profound shifts in the climate and cryosphere, and their connections to Hg cycling. Modeling results suggest climate influences seasonal and interannual variability of atmospheric Hg deposition. The clearest evidence of current climate change effects is for Hg transport from terrestrial catchments, where widespread permafrost thaw, glacier melt and coastal erosion are increasing the export of Hg to downstream environments. Recent estimates suggest Arctic permafrost is a large global reservoir of Hg, which is vulnerable to degradation with climate warming, although the fate of permafrost soil Hg is unclear. The increasing development of thermokarst features, the formation and expansion of thaw lakes, and increased soil erosion in terrestrial landscapes are increasing river transport of particulate-bound Hg and altering conditions for aquatic Hg transformations. Greater organic matter transport may also be influencing the downstream transport and fate of Hg. More severe and frequent wildfires within the Arctic and across boreal regions may be contributing to the atmospheric pool of Hg. Climate change influences on Hg biogeochemical cycling remain poorly understood. Seasonal evasion and retention of inorganic Hg may be altered by reduced sea-ice cover and higher chloride content in snow. Experimental evidence indicates warmer temperatures enhance methylmercury production in ocean and lake sediments as well as in tundra soils. Improved geographic coverage of measurements and modeling approaches are needed to better evaluate net effects of climate change and long-term implications for Hg contamination in the Arctic.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, Ecotoxicology and Wildlife Health Division, National Wildlife Research Centre, Ottawa, ON K1A 0H3, Canada.
| | - Melissa A McKinney
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Marc Amyot
- Groupe de recherche interuniversitaire en limnologie (GRIL), Département de sciences biologiques, Complexe des Sciences, Montréal, QC H2V 0B3, Canada
| | - Ashu Dastoor
- Environment and Climate Change Canada, Air Quality Research Division, Dorval, QC H9P 1J3, Canada
| | - Thomas A Douglas
- U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK 99709, USA
| | - Lars-Eric Heimbürger-Boavida
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, Marseille, France
| | - Jane Kirk
- Environment and Climate Change Canada, Aquatic Contaminants Research Division, Burlington, ON L7S 1A1, Canada
| | - Kimmo K Kahilainen
- Lammi Biological Station, University of Helsinki, Pääjärventie 320, FI-16900 Lammi, Finland
| | - Peter M Outridge
- Geological Survey of Canada, Natural Resources Canada, Ottawa, ON K1A 0E8, Canada
| | - Nicolas Pelletier
- Geography and Environmental Studies, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Henrik Skov
- Department of Environmental Science, iClimate, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Kyra St Pierre
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Jussi Vuorenmaa
- Finnish Environment Institute (SYKE), Latokartanonkaari 11, FI-00790 Helsinki, Finland
| | - Feiyue Wang
- Centre for Earth Observation Sciences (CEOS), Dept. of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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30
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Nádudvari Á, Cabała J, Marynowski L, Jabłońska M, Dziurowicz M, Malczewski D, Kozielska B, Siupka P, Piotrowska-Seget Z, Simoneit BRT, Szczyrba M. High concentrations of HgS, MeHg and toxic gas emissions in thermally affected waste dumps from hard coal mining in Poland. JOURNAL OF HAZARDOUS MATERIALS 2022; 431:128542. [PMID: 35248960 DOI: 10.1016/j.jhazmat.2022.128542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/13/2022] [Accepted: 02/20/2022] [Indexed: 06/14/2023]
Abstract
This study aims to provide numerous environmental research approaches to understand the formation of mineral and organic mercury compounds in self-heating coal waste dumps of the Upper Silesian Coal Basin (USCB). The results are combined with environmental and health risk assessments. The mineralogy comprised accessory minerals in the fine fraction of thermally affected waste, i.e., Hg sulfides, most likely cinnabar or metacinnabar. Moreover, other metals, e.g., Pb, Zn and Cu, were found as sulfide forms. Apart from Hg, the ICP-ES/MS data confirmed the high content of Mn, Zn, Pb, Hg, Cr and Ba in these wastes. The high concentration of available Hg resulted in elevated MeHg concentrations in the dumps. There were no correlations or trends between MeHg concentrations and elemental Hg, TS, TOC, and pH. Furthermore, we did not detect microbial genes responsible for Hg methylation. The organic compounds identified in waste and emitted gases, such as organic acids, or free methyl radicals, common in such burn environments, could be responsible for the formation of MeHg. The concentration levels of gases, e.g., benzene, formaldehyde, NH3, emitted by the vents, reached or surpassed acceptable levels numerous times. The potential ecological and human health risks of these dumps were moderate to very high due to the significant influence of the high Hg concentrations.
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Affiliation(s)
- Ádám Nádudvari
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland.
| | - Jerzy Cabała
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland
| | - Leszek Marynowski
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland
| | - Mariola Jabłońska
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland
| | - Maria Dziurowicz
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland
| | - Dariusz Malczewski
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland
| | - Barbara Kozielska
- Silesian University of Technology, Faculty of Power and Environmental Engineering, Department of Air Protection, 22B Konarskiego St., 44-100 Gliwice, Poland
| | - Piotr Siupka
- University of Silesia in Katowice, Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, Jagiellonska 28, 40-032 Katowice, Poland
| | - Zofia Piotrowska-Seget
- University of Silesia in Katowice, Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, Jagiellonska 28, 40-032 Katowice, Poland
| | - Bernd R T Simoneit
- Oregon State University, Department of Chemistry, College of Science, Corvallis, OR 97331, USA
| | - Mirosław Szczyrba
- University of Silesia in Katowice, Faculty of Natural Sciences, 60 Będzińska Street, 41-200 Sosnowiec, Poland
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Kim J, Kwon SY, Kim K, Han S. Import, export, and speciation of mercury in Kongsfjorden, Svalbard: Influences of glacier melt and river discharge. MARINE POLLUTION BULLETIN 2022; 179:113693. [PMID: 35525059 DOI: 10.1016/j.marpolbul.2022.113693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 04/07/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
The major sources and sinks of total mercury (THg) and methylmercury (MeHg) in Kongsfjorden were estimated based on spreadsheet-based ecological risk assessment for the fate of mercury (SERAFM). SERAFM was parameterized and calibrated to fit Kongsfjorden using the physical properties of the fjord, runoff coefficients of Hg, transformation rate constants of Hg, partition coefficients of Hg, Hg loadings from freshwater, and solid balance parameters. The modeled Hg concentrations in the seawater matched with the measured concentrations, with a mean bias of 12% and a calibration error of 0.035. The mass budget showed that the major THg sources were tidal inflow and glacial runoff, while the major MeHg sources were tidal inflow and in situ methylation in shallow halocline water, which agreed with the distributions of THg and MeHg in seawater. The coupling of observation and fate modeling in Kongsfjorden provides a basic understanding of Hg cycles in the Arctic fjords.
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Affiliation(s)
- Jihee Kim
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Kitae Kim
- Korea Polar Research Institute (KOPRI), Incheon 21990, Republic of Korea; Department of Polar Science, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Seunghee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
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32
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Yu RQ, Barkay T. Microbial mercury transformations: Molecules, functions and organisms. ADVANCES IN APPLIED MICROBIOLOGY 2022; 118:31-90. [PMID: 35461663 DOI: 10.1016/bs.aambs.2022.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Mercury (Hg) methylation, methylmercury (MeHg) demethylation, and inorganic redox transformations of Hg are microbe-mediating processes that determine the fate and cycling of Hg and MeHg in many environments, and by doing so influence the health of humans and wild life. The discovery of the Hg methylation genes, hgcAB, in the last decade together with advances in high throughput and genome sequencing methods, have resulted in an expanded appreciation of the diversity of Hg methylating microbes. This review aims to describe experimentally confirmed and recently discovered hgcAB gene-carrying Hg methylating microbes; phylogenetic and taxonomic analyses are presented. In addition, the current knowledge on transformation mechanisms, the organisms that carry them out, and the impact of environmental parameters on Hg methylation, MeHg demethylation, and inorganic Hg reduction and oxidation is summarized. This knowledge provides a foundation for future action toward mitigating the impact of environmental Hg pollution.
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Affiliation(s)
- Ri-Qing Yu
- Department of Biology, University of Texas at Tyler, Tyler, TX, United States.
| | - Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
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Zhang L, Philben M, Taş N, Johs A, Yang Z, Wullschleger SD, Graham DE, Pierce EM, Gu B. Unravelling biogeochemical drivers of methylmercury production in an Arctic fen soil and a bog soil. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 299:118878. [PMID: 35085651 DOI: 10.1016/j.envpol.2022.118878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 06/14/2023]
Abstract
Arctic tundra soils store a globally significant amount of mercury (Hg), which could be transformed to the neurotoxic methylmercury (MeHg) upon warming and thus poses serious threats to the Arctic ecosystem. However, our knowledge of the biogeochemical drivers of MeHg production is limited in these soils. Using substrate addition (acetate and sulfate) and selective microbial inhibition approaches, we investigated the geochemical drivers and dominant microbial methylators in 60-day microcosm incubations with two tundra soils: a circumneutral fen soil and an acidic bog soil, collected near Nome, Alaska, United States. Results showed that increasing acetate concentration had negligible influences on MeHg production in both soils. However, inhibition of sulfate-reducing bacteria (SRB) completely stalled MeHg production in the fen soil in the first 15 days, whereas addition of sulfate in the low-sulfate bog soil increased MeHg production by 5-fold, suggesting prominent roles of SRB in Hg(II) methylation. Without the addition of sulfate in the bog soil or when sulfate was depleted in the fen soil (after 15 days), both SRB and methanogens contributed to MeHg production. Analysis of microbial community composition confirmed the presence of several phyla known to harbor microorganisms associated with Hg(II) methylation in the soils. The observations suggest that SRB and methanogens were mainly responsible for Hg(II) methylation in these tundra soils, although their relative contributions depended on the availability of sulfate and possibly syntrophic metabolisms between SRB and methanogens.
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Affiliation(s)
- Lijie Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA; Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Michael Philben
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Neslihan Taş
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, USA
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Ziming Yang
- Department of Chemistry, Oakland University, Rochester, MI, 48309, USA
| | - Stan D Wullschleger
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - David E Graham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
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Chaudhary DK, Kim KH, Lee M, Kim H, Hong Y. Insights into Bacterial Community Structure and Metabolic Diversity of Mercury-Contaminated Sediments from Hyeongsan River, Pohang, South Korea. Curr Microbiol 2022; 79:156. [PMID: 35397046 DOI: 10.1007/s00284-022-02847-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
Abstract
This study investigated the bacterial community structure and metabolic diversity and their relationship with Hg and other environmental variables in sediments collected from different locations (HSR-1-HSR-6) in the Hyeongsan River estuary in South Korea. The results showed that the highest total mercury (THg) and methylmercury (MeHg) concentrations were in HSR-2, with values of 4585.3 µg/kg and 13.4 µg/kg, respectively. The lowest THg (31.9 µg/kg) and MeHg (0.1 µg/kg) concentrations were found in HSR-1. Sulfate and organic matter (OM) were more influential environmental variables, revealing a positive association with THg and MeHg and negatively affecting bacterial and metabolic diversities. Bacterial and metabolic diversities were also negatively impacted by the THg and MeHg concentrations. Proteobacteria and Bacteroidetes were abundantly distributed in all the sediments. The dominance of Proteobacteria was upscaled in all the heavily Hg-contaminated sites (HSR-2-HSR-6), and it was the only phylum that showed a significant positive correlation with THg, MeHg, and OM. The genera Sulfurovum and Sulfurimonas were abundantly observed in sites with high Hg contamination, whereas Congregibacter, Gaetbulibacter, Ilumatobacter, Methylotenera, Nevskia, and Sediminibacter were only detected in low Hg-contaminated sites (HSR-1). The community-level physiological profile data showed the highest (1.0) average well color development (AWCD) value in HSR-1 and the lowest (0.45) AWCD value in HSR-2. Overall, these results demonstrated the inhibitory effects of THg, MeHg, and other environmental variables on microbial communities and metabolic diversity. These findings broaden the current knowledge on the dynamics of bacterial and metabolic diversities in Hg-contaminated sediments and might be useful in the management of Hg pollution.
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Affiliation(s)
- Dhiraj Kumar Chaudhary
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong, 30019, Republic of Korea
| | - Kyung Hee Kim
- Water Environmental Engineering Research Division, National Institute of Environmental Research, Hwangyong-ro 42, Seogu, Incheon, 22689, Republic of Korea
| | - Mikyung Lee
- Water Environmental Engineering Research Division, National Institute of Environmental Research, Hwangyong-ro 42, Seogu, Incheon, 22689, Republic of Korea
| | - Hwansuk Kim
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong, 30019, Republic of Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong, 30019, Republic of Korea.
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35
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Bailon MX, Park M, Solis KL, Na Y, Chaudhary DK, Kim S, Hong Y. Reduction in mercury bioavailability to Asian clams (Corbicula fluminea) and changes in bacterial communities in sediments with activated carbon amendment. CHEMOSPHERE 2022; 291:132700. [PMID: 34710454 DOI: 10.1016/j.chemosphere.2021.132700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 08/23/2021] [Accepted: 10/24/2021] [Indexed: 06/13/2023]
Abstract
Activated carbon (AC) amendment is considered as one of the alternatives for managing and remediating mercury (Hg) contaminated sediments because of its high sorptive capacity and potential to immobilize the contaminant. For this study, the underlying mechanisms that control the reduction of Hg bioavailability in AC-amended estuarine sediments were investigated in box microcosm set-ups with 28-day Asian clam bioassay experiments. The application of diffusive gradients in thin film technique (DGT) revealed that the total mercury and methylmercury levels in sediment pore water decreased by 60%-75% in 1%-3% AC-amended sediments. This decrease subsequently led to a linear reduction in the Hg body burden in Asian clams, even at 1% sorbent mixing. These observations implied that AC amendment reduced the net flux of Hg into the pore water and overlying water, resulting in reduced Hg bioaccumulation in benthic organisms. The addition of AC to sediment also led to reduced dissolved organic carbon and several biogeochemical indicators (HS-, Mn, and Fe) in the pore water. Furthermore, the 16 S rRNA gene amplicon sequencing analysis revealed noticeable alterations in the microbial communities after AC amendment. The predominant phylum was Firmicutes in control sediment, Bacteroidetes in 1% AC-amended sediment, and Proteobacteria in both 2% and 3% AC-amended sediment samples. The genera-level analysis showed that the relative abundance of the Hg-methylators decreased as the level of AC amendment increased. These observations suggested that AC amendment decreased Hg bioavailability not only by physicochemical sorption but also by changing geochemical species and shifting the microbial community composition.
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Affiliation(s)
- Mark Xavier Bailon
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea; Department of Science and Technology, Philippine Science High School - Central Luzon Campus, Lily Hill, Clark Freeport Zone, Mabalacat City, Pampanga, 2010, Philippines
| | - Minoh Park
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea
| | - Kurt Louis Solis
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea
| | - Yeong Na
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea
| | - Dhiraj Kumar Chaudhary
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea
| | - Sungpyo Kim
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-ro, Sejong City, 30019, South Korea.
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36
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Proximity to Riparian Wetlands Increases Mercury Burden in Fish in the Upper St. Lawrence River. WATER 2022. [DOI: 10.3390/w14010070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mercury deposited in the Upper St. Lawrence River watershed by atmospheric deposition accumulated in riparian wetlands and is at risk of remobilization due to water level fluctuations. To examine if riparian wetlands are a source of mercury to fish, 174 yellow perch (Perca flavescens) and 145 round gobies (Neogobius melanostomus) were collected in 2019 from eight wetland and seven non-wetland habitats throughout the Upper St. Lawrence River. Mercury levels were significantly (p < 0.01) higher in fish collected from wetlands than those collected from non-wetland habitats for both yellow perch and round goby. Perch had mercury concentrations of 74.5 ± 35.4 ng/g dry wt in wetlands compared to 59.9 ± 23.0 ng/g dry wt in non-wetlands. Goby had mercury concentrations of 55.4 ± 13.8 ng/g dry wt in wetlands and non-wetland concentrations of 41.0 ± 14.0 ng/g dry wt. Riparian wetlands are areas of elevated mercury methylation and mobilization in the Upper St. Lawrence River and consequences to predators should be considered from the perspective of both wildlife preservation as well as fish consumption advisories for public health concerns.
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Liu J, Lu B, Poulain AJ, Zhang R, Zhang T, Feng X, Meng B. The underappreciated role of natural organic matter bond Hg(II) and nanoparticulate HgS as substrates for methylation in paddy soils across a Hg concentration gradient. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 292:118321. [PMID: 34634402 DOI: 10.1016/j.envpol.2021.118321] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/07/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
Rice consumption is the major pathway for human methylmercury (MeHg) exposure in inland China, especially in mercury (Hg) contaminated regions. MeHg production, a microbially driven process, depends on both the chemical speciation of inorganic divalent mercury, Hg(II), that determines Hg bioavailability for methylation. Studies have shown that Hg(II) speciation in contaminated paddy soils is mostly controlled by natural organic matter and sulfide levels, which are typically thought to limit Hg mobility and bioavailability. Yet, high levels of MeHg are found in rice, calling for reconsideration of the nature of Hg species bioavailable to methylators in paddy soils. Here, we conducted incubation experiments using a multi-isotope tracer technique including 198Hg(NO3)2, natural organic matter bond Hg(II) (NOM-199Hg(II)), ferrous sulfide sorbed Hg(II) (≡FeS-200Hg(II)), and nanoparticulate mercuric sulfide (nano-202HgS), to investigate the relative importance of geochemically diverse yet relevant Hg(II) species on Hg methylation in paddy soils across a Hg concentration gradient. We show that methylation rates for all Hg(II) species tested decreased with increasing Hg concentrations, and that methylation rates using NOM-199Hg(II) and nano-202HgS as substrates were similar or greater than rates obtained using the labile 198Hg(NO3)2 substrate. ≡FeS-200Hg(II) yielded the lowest methylation rate in all sites, and thus the formation of FeS is likely a sink for labile 198Hg(NO3)2 in sulfide-rich paddy soils. Moreover, the variability in the methylation data for a given site (1 to 5-fold variation depending on the Hg species) was smaller than what was observed across the Hg concentration gradient (103-104 fold variation between sites). These findings emphasize that at broad spatial scales, site-specific characteristics, such as microbial community structure, need to be taken into consideration, alongside the nature of the Hg substrate available for methylation, to determine net MeHg production. This study highlights the importance of developing site-specific strategies for remediating Hg pollution.
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Affiliation(s)
- Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Benqi Lu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Alexandre J Poulain
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Rui Zhang
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin, 300350, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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Nitrospina-like Bacteria Are Dominant Potential Mercury Methylators in Both the Oyashio and Kuroshio Regions of the Western North Pacific. Microbiol Spectr 2021; 9:e0083321. [PMID: 34494859 PMCID: PMC8557936 DOI: 10.1128/spectrum.00833-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Highly neurotoxic methylmercury (MeHg) accumulates in marine organisms, thereby negatively affecting human and environmental health. Recent studies have revealed that oceanic prokaryotes harboring the hgcAB gene pair are involved in Hg methylation. Presently, little is known about the distribution and phylogeny of these genes in distinct oceanic regions of the western North Pacific. In this study, we used metagenomics to survey the distribution of hgcAB genes in the seawater columns of the subarctic Oyashio region and the subtropical Kuroshio region. The hgcAB genes were detected in the MeHg-rich offshore mesopelagic layers of both the Oyashio region, which is a highly productive area in the western North Pacific, and the Kuroshio region, which has low productivity. Comparative analysis revealed that hgcAB genes belonging to the Nitrospina-like lineage were dominant in the MeHg-rich mesopelagic layers of both regions. These results indicate that Nitrospina-like bacteria are the dominant Hg methylators in the mesopelagic layers throughout the western North Pacific. IMPORTANCE MeHg is highly neurotoxic and accumulates in marine organisms. Thus, understanding MeHg production in seawater is critical for environmental and human health. Recent studies have shown that microorganisms harboring mercury-methylating genes (hgcA and hgcB) are involved in MeHg production in several marine environments. Knowing the distribution and phylogeny of hgcAB genes in seawater columns can facilitate assessment of microbial MeHg production in the ocean. We report that hgcAB genes affiliated with the microaerophilic Nitrospina lineage were detected in the MeHg-rich mesopelagic layers of two hydrologically distinct oceanic regions of the western North Pacific. This finding facilitates understanding of the microbial Hg methylation and accumulation in seawater columns of the western North Pacific.
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Roth S, Poulin BA, Baumann Z, Liu X, Zhang L, Krabbenhoft DP, Hines ME, Schaefer JK, Barkay T. Nutrient Inputs Stimulate Mercury Methylation by Syntrophs in a Subarctic Peatland. Front Microbiol 2021; 12:741523. [PMID: 34675906 PMCID: PMC8524442 DOI: 10.3389/fmicb.2021.741523] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 09/13/2021] [Indexed: 11/13/2022] Open
Abstract
Climate change dramatically impacts Arctic and subarctic regions, inducing shifts in wetland nutrient regimes as a consequence of thawing permafrost. Altered hydrological regimes may drive changes in the dynamics of microbial mercury (Hg) methylation and bioavailability. Important knowledge gaps remain on the contribution of specific microbial groups to methylmercury (MeHg) production in wetlands of various trophic status. Here, we measured aqueous chemistry, potential methylation rates (kmeth), volatile fatty acid (VFA) dynamics in peat-soil incubations, and genetic potential for Hg methylation across a groundwater-driven nutrient gradient in an interior Alaskan fen. We tested the hypotheses that (1) nutrient inputs will result in increased methylation potentials, and (2) syntrophic interactions contribute to methylation in subarctic wetlands. We observed that concentrations of nutrients, total Hg, and MeHg, abundance of hgcA genes, and rates of methylation in peat incubations (kmeth) were highest near the groundwater input and declined downgradient. hgcA sequences near the input were closely related to those from sulfate-reducing bacteria (SRB), methanogens, and syntrophs. Hg methylation in peat incubations collected near the input source (FPF2) were impacted by the addition of sulfate and some metabolic inhibitors while those down-gradient (FPF5) were not. Sulfate amendment to FPF2 incubations had higher kmeth relative to unamended controls despite no effect on kmeth from addition of the sulfate reduction inhibitor molybdate. The addition of the methanogenic inhibitor BES (25 mM) led to the accumulation of VFAs, but unlike molybdate, it did not affect Hg methylation rates. Rather, the concurrent additions of BES and molybdate significantly decreased kmeth, suggesting a role for interactions between SRB and methanogens in Hg methylation. The reduction in kmeth with combined addition of BES and molybdate, and accumulation of VFA in peat incubations containing BES, and a high abundance of syntroph-related hgcA sequences in peat metagenomes provide evidence for MeHg production by microorganisms growing in syntrophy. Collectively the results suggest that wetland nutrient regimes influence the activity of Hg methylating microorganisms and, consequently, Hg methylation rates. Our results provide key information about microbial Hg methylation and methylating communities under nutrient conditions that are expected to become more common as permafrost soils thaw.
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Affiliation(s)
- Spencer Roth
- Department of Environmental Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States.,Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Brett A Poulin
- Department of Environmental Toxicology, University of California, Davis, Davis, CA, United States
| | - Zofia Baumann
- Department of Marine Sciences, University of Connecticut, Groton, CT, United States
| | - Xiao Liu
- Department of Biological Sciences, University of Massachusetts, Lowell, MA, United States.,Department of Physical and Environmental Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX, United States
| | - Lin Zhang
- Department of Physical and Environmental Sciences, Texas A&M University - Corpus Christi, Corpus Christi, TX, United States
| | - David P Krabbenhoft
- United States Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, Middleton, WI, United States
| | - Mark E Hines
- Department of Biological Sciences, University of Massachusetts, Lowell, MA, United States
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
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Bowman KL, Lamborg CH, Agather AM, Hammerschmidt CR. The role of plastic debris in the biogeochemical cycle of mercury in Lake Erie and San Francisco Bay. MARINE POLLUTION BULLETIN 2021; 171:112768. [PMID: 34343756 DOI: 10.1016/j.marpolbul.2021.112768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
The accumulation of plastic debris that concentrates hydrophobic compounds and microbial communities creates the potential for altered aquatic biogeochemical cycles. This study investigated the role of plastic debris in the biogeochemical cycling of mercury in surface waters of the San Francisco Bay, Sacramento River, Lake Erie, and in coastal seawater. Total mercury and monomethylmercury were measured on plastic debris from all study sites. Plastic-bound microbial communities from Lake Erie and San Francisco Bay contained several lineages of known mercury methylating microbes, however the hgcAB gene cluster was not detected using polymerase chain reaction. These plastic-bound microbial communities also contained species that possess the mer operon, and merA genes were detected using polymerase chain reaction. In coastal seawater incubations, rapid mercury methylation percentages were greater in the presence of microplastics and demethylation percentages decreased as monomethylmercury additions adsorbed to microplastics. These findings suggest that plastic pollution has the potential to alter the biogeochemical cycling of mercury in aquatic ecosystems.
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Affiliation(s)
- Katlin L Bowman
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States of America; Moss Landing Marine Laboratories, Moss Landing, CA 95039, United States of America.
| | - Carl H Lamborg
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, United States of America
| | - Alison M Agather
- Department of Earth & Environmental Sciences, Wright State University, Dayton, OH 45435, United States of America; Cherokee Nation Strategic Programs, Arlington, VA 22202, United States of America
| | - Chad R Hammerschmidt
- Department of Earth & Environmental Sciences, Wright State University, Dayton, OH 45435, United States of America
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Paudyal R, Kang S, Guo J, Tripathee L, Sharma CM, Huang J, Li Y, Yan F, Wang K, Chen J, Qin X, Sillanpaa M. Mercury sources and physicochemical characteristics in ice, snow, and meltwater of the Laohugou Glacier Basin, China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:51530-51543. [PMID: 33987720 DOI: 10.1007/s11356-021-14334-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
In this work, samples of surface snow, surface ice, snow pit and meltwater from the Laohugou Glacier No. 12 on the northern edge of Tibetan Plateau (TP) were collected during the summer of 2015. The average concentration of Hg in surface snow/ice was 22.41 ng L-1, while the percentage of dissolved mercury (HgD) was observed to be around 26%. An altitudinal magnification of Hg was not observed for surface snow; however, in contrast, a significant positive magnification of Hg with altitude was observed in the surface ice. A higher concentration of Hg corresponded with the dust layer of the snow pit. It was observed that about 42% of Hg was lost from the surface snow when the glacier was exposed to sunlight within the first 24 h indicating some Hg was emitted back to the atmosphere while some were percolated downwards. The result from the principal component analysis (PCA) showed that the sources of Hg in Laohugou Glacier No. 12 were from crustal and biomass burning. Finally, it was estimated that total export of Hg from the outlet river of Laohugou glacier No. 12 in the year 2015 was about 1439.46 g yr-1 with yield of 22.77 μg m2 yr-1. This study provides valuable insights for understanding the behavior of Hg in the glacier of the northern Tibetan Plateau.
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Affiliation(s)
- Rukumesh Paudyal
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
- Himalayan Environment Research Institute (HERI), Kathmandu, Nepal
| | - Shichang Kang
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China.
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100085, China.
- Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Junming Guo
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
| | - Lekhendra Tripathee
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
- Himalayan Environment Research Institute (HERI), Kathmandu, Nepal
| | - Chhatra Mani Sharma
- Himalayan Environment Research Institute (HERI), Kathmandu, Nepal
- Central Department of Environmental Science, Tribhuvan University, Kathmandu, Nepal
| | - Jie Huang
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100085, China
- Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yang Li
- Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Fangping Yan
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
- Laboratory of Green Chemistry, Lappeenranta University of Technology, 50130, Mikkeli, Finland
| | - Kun Wang
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
| | - Jizu Chen
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
| | - Xiang Qin
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China
- Qilian Shan Station of Glaciology and Ecological Environment, Chinese Academy of Science, Lanzhou, China
| | - Mika Sillanpaa
- Institute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam
- Faculty of Environment and Chemical Engineering, Duy Tan University, Da Nang, 550000, Vietnam
- School of Civil Engineering and Surveying, Faculty of Health, Engineering and Sciences, University of Southern Queensland, West Street, Toowoomba, QLD, 4350, Australia
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Du H, Sun T, Liu Y, An S, Xie H, Wang D, Igarashi Y, Imanaka T, Luo F, Ma M. Bacteria and archaea involved in anaerobic mercury methylation and methane oxidation in anaerobic sulfate-rich reactors. CHEMOSPHERE 2021; 274:129773. [PMID: 33556662 DOI: 10.1016/j.chemosphere.2021.129773] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 06/12/2023]
Abstract
The identification of dominant microbes in anaerobic mercury (Hg) methylation, methylmercury (MeHg) demethylation, and methane oxidation as sulfate-reducing bacteria, methanogens or, probably, anaerobic methanotrophic archaea (ANMEs) is of great interest. To date, however, the interrelationship of bacteria and archaea involved in these processes remains unclear. Here, we demonstrated the dynamics of microorganisms participating in these processes. Anaerobic fixed-bed reactors were operated with swine manure and sludge to produce methane stably, and then, sulfate (reactor C), sulfate and Hg(II) (reactor H), and sulfate and MeHg (reactor M) were added, and the reactors were operated for 120 d, divided equally into four periods, P1-P4. The bacterial compositions changed nonsignificantly, whereas Methanosaeta in reactors H and M decreased significantly, revealing that it was irrelevant for Hg transformation. The abundances of Syntrophomonadaceae, Methanoculleus, Candidatus Methanogranum and Candidatus Methanoplasma increased continuously with time; these species probably functioned in these processes, but further evidence is needed. Desulfocella and Desulfobacterium dominated first but eventually almost vanished, while the dominant archaeal genera Methanogenium, Methanoculleus and Methanocorpusculum were closely related to ANME-1 and ANME-2. PLS-DA results indicated that both bacteria and archaea in different periods in the three reactors were clustered separately, implying that the microbial compositions in the same periods were similar and changed markedly with time.
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Affiliation(s)
- Hongxia Du
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Tao Sun
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yang Liu
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Siwei An
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Haiying Xie
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Dingyong Wang
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yasuo Igarashi
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Tadayuki Imanaka
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Feng Luo
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China.
| | - Ming Ma
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, 400715, China; Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, 400715, China.
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Christakis CA, Barkay T, Boyd ES. Expanded Diversity and Phylogeny of mer Genes Broadens Mercury Resistance Paradigms and Reveals an Origin for MerA Among Thermophilic Archaea. Front Microbiol 2021; 12:682605. [PMID: 34248899 PMCID: PMC8261052 DOI: 10.3389/fmicb.2021.682605] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/28/2021] [Indexed: 11/13/2022] Open
Abstract
Mercury (Hg) is a highly toxic element due to its high affinity for protein sulfhydryl groups, which upon binding, can destabilize protein structure and decrease enzyme activity. Prokaryotes have evolved enzymatic mechanisms to detoxify inorganic Hg and organic Hg (e.g., MeHg) through the activities of mercuric reductase (MerA) and organomercury lyase (MerB), respectively. Here, the taxonomic distribution and evolution of MerAB was examined in 84,032 archaeal and bacterial genomes, metagenome assembled genomes, and single-cell genomes. Homologs of MerA and MerB were identified in 7.8 and 2.1% percent of genomes, respectively. MerA was identified in the genomes of 10 archaeal and 28 bacterial phyla previously unknown to code for this functionality. Likewise, MerB was identified in 2 archaeal and 11 bacterial phyla previously unknown to encode this functionality. Surprisingly, homologs of MerB were identified in a number of genomes (∼50% of all MerB-encoding genomes) that did not encode MerA, suggesting alternative mechanisms to detoxify Hg(II) once it is generated in the cytoplasm. Phylogenetic reconstruction of MerA place its origin in thermophilic Thermoprotei (Crenarchaeota), consistent with high levels of Hg(II) in geothermal environments, the natural habitat of this archaeal class. MerB appears to have been recruited to the mer operon relatively recently and likely among a mesophilic ancestor of Euryarchaeota and Thaumarchaeota. This is consistent with the functional dependence of MerB on MerA and the widespread distribution of mesophilic microorganisms that methylate Hg(II) at lower temperature. Collectively, these results expand the taxonomic and ecological distribution of mer-encoded functionalities, and suggest that selection for Hg(II) and MeHg detoxification is dependent not only on the availability and type of mercury compounds in the environment but also the physiological potential of the microbes who inhabit these environments. The expanded diversity and environmental distribution of MerAB identify new targets to prioritize for future research.
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Affiliation(s)
- Christos A. Christakis
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Eric S. Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
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44
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Millera Ferriz L, Ponton DE, Storck V, Leclerc M, Bilodeau F, Walsh DA, Amyot M. Role of organic matter and microbial communities in mercury retention and methylation in sediments near run-of-river hydroelectric dams. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 774:145686. [PMID: 33609815 DOI: 10.1016/j.scitotenv.2021.145686] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/08/2021] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
Run-of-river power plants (RoRs) are expected to triple in number over the next decades in Canada. These structures are not anticipated to considerably promote the mobilization and transport of mercury (Hg) and its subsequent microbial transformation to methylmercury (MeHg), a neurotoxin able to biomagnify in food webs up to humans. To test whether construction of RoRs had an effect on Hg transport and transformation, we studied Hg and MeHg concentrations, organic matter contents and methylating microbial community abundance and composition in the sediments of a section of the St. Maurice River (Quebec, Canada). This river section has been affected by the construction of two RoR dams and its watershed has been disturbed by a forest fire, logging, and the construction of wetlands. Higher total Hg (THg) and MeHg concentrations were observed in the surface sediments of the flooded sites upstream of the RoRs. These peaks in THg and MeHg were correlated with organic matter proportions in the sediments (r2 = 0.87 and 0.82, respectively). In contrast, the proportion of MeHg, a proxy for methylation potential, was best explained by the carbon to nitrogen ratio suggesting the importance of terrigenous organic matter as labile substrate for Hg methylation in this system. Metagenomic analysis of Hg-methylating communities based on the hgcA functional gene marker indicated an abundance of methanogens, sulfate reducers and fermenters, suggesting that these metabolic guilds may be primary Hg methylators in these surface sediments. We propose that RoR pondages act as traps for sediments, organic matter and Hg, and that this retention can be amplified by other disturbances of the watershed such as forest fire and logging. RoR flooded sites can be conducive to Hg methylation in sediments and may act as gateways for bioaccumulation and biomagnification of MeHg along food webs, particularly in disturbed watersheds.
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Affiliation(s)
- L Millera Ferriz
- Département de sciences biologiques, Université de Montréal, Montreal H2V 2S9, QC, Canada; Biology Department, Concordia University, Montreal H4B 1R6, QC, Canada; GRIL, Groupe de Recherche Interuniversitaire en Limnologie, Département de sciences biologiques, Université de Montréal, Campus MIL, Montreal H3C 3J7, QC, Canada
| | - D E Ponton
- Département de sciences biologiques, Université de Montréal, Montreal H2V 2S9, QC, Canada; GRIL, Groupe de Recherche Interuniversitaire en Limnologie, Département de sciences biologiques, Université de Montréal, Campus MIL, Montreal H3C 3J7, QC, Canada
| | - V Storck
- Département de sciences biologiques, Université de Montréal, Montreal H2V 2S9, QC, Canada; Biology Department, Concordia University, Montreal H4B 1R6, QC, Canada
| | - M Leclerc
- Département de sciences biologiques, Université de Montréal, Montreal H2V 2S9, QC, Canada; GRIL, Groupe de Recherche Interuniversitaire en Limnologie, Département de sciences biologiques, Université de Montréal, Campus MIL, Montreal H3C 3J7, QC, Canada
| | - F Bilodeau
- Hydro-Québec Production, Environment Department, Montreal, QC, Canada
| | - D A Walsh
- Biology Department, Concordia University, Montreal H4B 1R6, QC, Canada; GRIL, Groupe de Recherche Interuniversitaire en Limnologie, Département de sciences biologiques, Université de Montréal, Campus MIL, Montreal H3C 3J7, QC, Canada
| | - M Amyot
- Département de sciences biologiques, Université de Montréal, Montreal H2V 2S9, QC, Canada; GRIL, Groupe de Recherche Interuniversitaire en Limnologie, Département de sciences biologiques, Université de Montréal, Campus MIL, Montreal H3C 3J7, QC, Canada.
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Gilmour CC, Soren AB, Gionfriddo CM, Podar M, Wall JD, Brown SD, Michener JK, Urriza MSG, Elias DA. Pseudodesulfovibrio mercurii sp. nov., a mercury-methylating bacterium isolated from sediment. Int J Syst Evol Microbiol 2021; 71. [PMID: 33570484 DOI: 10.1099/ijsem.0.004697] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The sulfate-reducing, mercury-methylating strain ND132T was isolated from the brackish anaerobic bottom sediments of Chesapeake Bay, USA. Capable of high levels of mercury (Hg) methylation, ND132T has been widely used as a model strain to study the process and to determine the genetic basis of Hg methylation. Originally called Desulfovibrio desulfuricans ND132T on the basis of an early partial 16S rRNA sequence, the strain has never been formally described. Phylogenetic and physiological traits place this strain within the genus Pseudodesulfovibrio, in the recently reclassified phylum Desulfobacterota (formerly Deltaproteobacteria). ND132T is most closely related to Pseudodesulfovibrio hydrargyri BerOc1T and Pseudodesulfovibrio indicus J2T. Analysis of average nucleotide identity (ANI) of whole-genome sequences showed roughly 88 % ANI between P. hydrargyri BerOc1T and ND132T, and 84 % similarity between ND132T and P. indicus J2T. These cut-off scores <95 %, along with a multi-gene phylogenetic analysis of members of the family Desulfovibrionacea, and differences in physiology indicate that all three strains represent separate species. The Gram-stain-negative cells are vibrio-shaped, motile and not sporulated. ND132T is a salt-tolerant mesophile with optimal growth in the laboratory at 32 °C, 2 % salinity, and pH 7.8. The DNA G+C content of the genomic DNA is 65.2 %. It is an incomplete oxidizer of short chain fatty acids, using lactate, pyruvate and fumarate with sulfate or sulfite as the terminal electron acceptors. ND132T can respire fumarate using pyruvate as an electron donor. The major fatty acids are iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0, iso-C17 : 1ω9c and anteiso-C17 : 0. We propose the classification of strain ND132T (DSM 110689, ATCC TSD-224) as the type strain Pseudodesulfovibrio mercurii sp. nov.
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Affiliation(s)
| | | | - Caitlin M Gionfriddo
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.,Smithsonian Environmental Research Center, Edgewater, Maryland, USA
| | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Judy D Wall
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Steven D Brown
- Present address: LanzaTech, Skokie, Illinois, USA.,Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Joshua K Michener
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | | | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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46
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Fuhrmann BC, Beutel MW, O'Day PA, Tran C, Funk A, Brower S, Pasek J, Seelos M. Effects of mercury, organic carbon, and microbial inhibition on methylmercury cycling at the profundal sediment-water interface of a sulfate-rich hypereutrophic reservoir. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 268:115853. [PMID: 33120160 DOI: 10.1016/j.envpol.2020.115853] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Methylmercury (MeHg) produced by anaerobic bacteria in lakes and reservoirs, poses a threat to ecosystem and human health due to its ability to bioaccumulate in aquatic food webs. This study used 48-hr microcosm incubations of profundal sediment and bottom water from a sulfate-rich, hypereutrophic reservoir to assess seasonal patterns of MeHg cycling under various treatments. Treatments included addition of air, Hg(II), organic carbon, and microbial inhibitors. Both aeration and sodium molybdate, a sulfate-reducing bacteria (SRB) inhibitor, generally decreased MeHg concentration in microcosm water, likely by inhibiting SRB activity. The methanogenic inhibitor bromoethanesulfonate increased MeHg concentration 2- to 4- fold, suggesting that methanogens were potent demethylators. Pyruvate increased MeHg concentration under moderately reduced conditions, likely by stimulating SRB, but decreased it under highly reduced conditions, likely by stimulating methanogens. Acetate increased MeHg concentration, likely due to the stimulation of acetotrophic SRB. Results suggest that iron-reducing bacteria (IRB) were not especially prominent methylators and MeHg production at the sediment-water interface is elevated under moderately reduced conditions corresponding with SRB activity. In contrast, it is suppressed under oxic conditions due to low SRB activity, and under highly reduced conditions (<-100 mV) due to enhanced demethylation by methanogens.
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Affiliation(s)
- Byran C Fuhrmann
- University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA.
| | - Marc W Beutel
- University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA
| | - Peggy A O'Day
- University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA
| | - Christian Tran
- Environmental Analytical Laboratory, University of California, 5200 North Lake Rd, Merced, CA, 95340, USA
| | - Andrew Funk
- City of San Diego, Public Utilities Department, 9192 Topaz Way, San Diego, CA, 92123, USA
| | - Sarah Brower
- City of San Diego, Public Utilities Department, 9192 Topaz Way, San Diego, CA, 92123, USA
| | - Jeffery Pasek
- City of San Diego, Public Utilities Department, 9192 Topaz Way, San Diego, CA, 92123, USA
| | - Mark Seelos
- University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA
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47
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Wang Y, Roth S, Schaefer JK, Reinfelder JR, Yee N. Production of methylmercury by methanogens in mercury contaminated estuarine sediments. FEMS Microbiol Lett 2020; 367:6006876. [PMID: 33242089 DOI: 10.1093/femsle/fnaa196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/24/2020] [Indexed: 11/14/2022] Open
Abstract
Anaerobic bacteria are known to produce neurotoxic methylmercury [MeHg] when elemental mercury [Hg(0)] is provided as the sole mercury source. In this study, we examined the formation of MeHg in anaerobic incubations of sediment collected from the San Jacinto River estuary (Texas, USA) amended with aqueous Hg(0) to investigate the microbial communities involved in the conversion of Hg(0) to MeHg. The results show that the addition of the methanogen inhibitor 2-bromoethanesulfonate (BES) significantly decreased MeHg production. The mercury methylation gene, hgcA, was detected in these sediments using archaeal specific primers, and 16S rRNA sequencing showed that a member of the Methanosarcinaceae family of methanogens was active. These results suggest that methanogenic archaea play an underappreciated role in the production of MeHg in estuarine sediments contaminated with Hg(0).
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Affiliation(s)
- Yuwei Wang
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| | - Spencer Roth
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA.,Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, 76 Lipman Drive, NJ 08901, USA
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
| | - Nathan Yee
- Department of Environmental Sciences, Rutgers University, New Brunswick, 14 College Farm Road, NJ 08901, USA
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48
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Peterson BD, McDaniel EA, Schmidt AG, Lepak RF, Janssen SE, Tran PQ, Marick RA, Ogorek JM, DeWild JF, Krabbenhoft DP, McMahon KD. Mercury Methylation Genes Identified across Diverse Anaerobic Microbial Guilds in a Eutrophic Sulfate-Enriched Lake. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15840-15851. [PMID: 33228362 PMCID: PMC9741811 DOI: 10.1021/acs.est.0c05435] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Mercury (Hg) methylation is a microbially mediated process that converts inorganic Hg into bioaccumulative, neurotoxic methylmercury (MeHg). The metabolic activity of methylating organisms is highly dependent on biogeochemical conditions, which subsequently influences MeHg production. However, our understanding of the ecophysiology of methylators in natural ecosystems is still limited. Here, we identified potential locations of MeHg production in the anoxic, sulfidic hypolimnion of a freshwater lake. At these sites, we used shotgun metagenomics to characterize microorganisms with the Hg-methylation gene hgcA. Putative methylators were dominated by hgcA sequences divergent from those in well-studied, confirmed methylators. Using genome-resolved metagenomics, we identified organisms with hgcA (hgcA+) within the Bacteroidetes and the recently described Kiritimatiellaeota phyla. We identified hgcA+ genomes derived from sulfate-reducing bacteria, but these accounted for only 22% of hgcA+ genome coverage. The most abundant hgcA+ genomes were from fermenters, accounting for over half of the hgcA gene coverage. Many of these organisms also mediate hydrolysis of polysaccharides, likely from cyanobacterial blooms. This work highlights the distribution of the Hg-methylation genes across microbial metabolic guilds and indicate that primary degradation of polysaccharides and fermentation may play an important but unrecognized role in MeHg production in the anoxic hypolimnion of freshwater lakes.
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Affiliation(s)
- Benjamin D. Peterson
- Environmental Science & Technology Program, University of Wisconsin - Madison, 660 N. Park Street, Madison, WI 53706, USA
- Corresponding author:
| | - Elizabeth A. McDaniel
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
| | - Anna G. Schmidt
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
| | - Ryan F. Lepak
- Environmental Science & Technology Program, University of Wisconsin - Madison, 660 N. Park Street, Madison, WI 53706, USA
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA
| | - Sarah E. Janssen
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - Patricia Q. Tran
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin - Madison, 250 N. Mills St.Madison, WI 53706, USA
| | - Robert A. Marick
- Department of Biochemistry, University of Wisconsin - Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Jacob M. Ogorek
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - John F. DeWild
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - David P. Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - Katherine D. McMahon
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
- Department of Civil and Environmental Engineering, University of Wisconsin – Madison, 1415 Engineering Drive, Madison WI 53706, USA
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49
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Jones DS, Johnson NW, Mitchell CPJ, Walker GM, Bailey JV, Pastor J, Swain EB. Diverse Communities of hgcAB+ Microorganisms Methylate Mercury in Freshwater Sediments Subjected to Experimental Sulfate Loading. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14265-14274. [PMID: 33138371 DOI: 10.1021/acs.est.0c02513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Methylmercury (MeHg) is a bioaccumulative neurotoxin produced by certain sulfate-reducing bacteria and other anaerobic microorganisms. Because microorganisms differ in their capacity to methylate mercury, the abundance and distribution of methylating populations may determine MeHg production in the environment. We compared rates of MeHg production and the distribution of hgcAB genes in epilimnetic sediments from a freshwater lake that were experimentally amended with sulfate levels from 7 to 300 mg L-1. The most abundant hgcAB sequences were associated with clades of Methanomicrobia, sulfate-reducing Deltaproteobacteria, Spirochaetes, and unknown environmental sequences. The hgcAB+ communities from higher sulfate amendments were less diverse and had relatively more Deltaproteobacteria, whereas the communities from lower amendments were more diverse with a larger proportion of hgcAB sequences affiliated with other clades. Potential methylation rate constants varied 52-fold across the experiment. Both potential methylation rate constants and % MeHg were the highest in sediments from the lowest sulfate amendments, which had the most diverse hgcAB+ communities and relatively fewer hgcAB genes from clades associated with sulfate reduction. Although pore water sulfide concentration covaried with hgcAB diversity across our experimental sulfate gradient, major changes in the community of hgcAB+ organisms occurred prior to a significant buildup of sulfide in pore waters. Our results indicate that methylating communities dominated by diverse anaerobic microorganisms that do not reduce sulfate can produce MeHg as effectively as communities dominated by sulfate-reducing populations.
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Affiliation(s)
- Daniel S Jones
- BioTechnology Institute, University of Minnesota, Saint Paul 55108, Minnesota, United States
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis 55455, Minnesota, United States
- Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro 87801, New Mexico, United States
- National Cave and Karst Research Institute, Carlsbad, New Mexico 88220, United States
| | - Nathan W Johnson
- Department of Civil Engineering, University of Minnesota Duluth, Duluth, Minnesota 55812, United States
| | - Carl P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto-Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Gabriel M Walker
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - Jake V Bailey
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - John Pastor
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota 55812, United States
| | - Edward B Swain
- Minnesota Pollution Control Agency, Saint Paul, Minnesota 55155, United States
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50
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Gionfriddo CM, Wymore AM, Jones DS, Wilpiszeski RL, Lynes MM, Christensen GA, Soren A, Gilmour CC, Podar M, Elias DA. An Improved hgcAB Primer Set and Direct High-Throughput Sequencing Expand Hg-Methylator Diversity in Nature. Front Microbiol 2020; 11:541554. [PMID: 33123100 PMCID: PMC7573106 DOI: 10.3389/fmicb.2020.541554] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 08/25/2020] [Indexed: 01/27/2023] Open
Abstract
The gene pair hgcAB is essential for microbial mercury methylation. Our understanding of its abundance and diversity in nature is rapidly evolving. In this study we developed a new broad-range primer set for hgcAB, plus an expanded hgcAB reference library, and used these to characterize Hg-methylating communities from diverse environments. We applied this new Hg-methylator database to assign taxonomy to hgcA sequences from clone, amplicon, and metagenomic datasets. We evaluated potential biases introduced in primer design, sequence length, and classification, and suggest best practices for studying Hg-methylator diversity. Our study confirms the emerging picture of an expanded diversity of HgcAB-encoding microbes in many types of ecosystems, with abundant putative mercury methylators Nitrospirae and Chloroflexi in several new environments including salt marsh and peat soils. Other common microbes encoding HgcAB included Phycisphaerae, Aminicenantes, Spirochaetes, and Elusimicrobia. Combined with high-throughput amplicon specific sequencing, the new primer set also indentified novel hgcAB sequences similar to Lentisphaerae, Bacteroidetes, Atribacteria, and candidate phyla WOR-3 and KSB1 bacteria. Gene abundance data also corroborate the important role of two "classic" groups of methylators (Deltaproteobacteria and Methanomicrobia) in many environments, but generally show a scarcity of hgcAB+ Firmicutes. The new primer set was developed to specifically target hgcAB sequences found in nature, reducing degeneracy and providing increased sensitivity while maintaining broad diversity capture. We evaluated mock communities to confirm primer improvements, including culture spikes to environmental samples with variable DNA extraction and PCR amplification efficiencies. For select sites, this new workflow was combined with direct high-throughput hgcAB sequencing. The hgcAB diversity generated by direct amplicon sequencing confirmed the potential for novel Hg-methylators previously identified using metagenomic screens. A new phylogenetic analysis using sequences from freshwater, saline, and terrestrial environments showed Deltaproteobacteria HgcA sequences generally clustered among themselves, while metagenome-resolved HgcA sequences in other phyla tended to cluster by environment, suggesting horizontal gene transfer into many clades. HgcA from marine metagenomes often formed distinct subtrees from those sequenced from freshwater ecosystems. Overall the majority of HgcA sequences branch from a cluster of HgcAB fused proteins related to Thermococci, Atribacteria (candidate division OP9), Aminicenantes (OP8), and Chloroflexi. The improved primer set and library, combined with direct amplicon sequencing, provide a significantly improved assessment of the abundance and diversity of hgcAB+ microbes in nature.
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Affiliation(s)
- Caitlin M Gionfriddo
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ann M Wymore
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Daniel S Jones
- BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.,Department of Earth Sciences, Minneapolis, MN, United States
| | - Regina L Wilpiszeski
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Mackenzie M Lynes
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Geoff A Christensen
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ally Soren
- Smithsonian Environmental Research Center, Edgewater, MD, United States
| | | | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
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