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Li S, Li Z, Wu M, Zhou Y, Tang W, Zhong H. Mercury transformations in algae, plants, and animals: The occurrence, mechanisms, and gaps. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 911:168690. [PMID: 38000748 DOI: 10.1016/j.scitotenv.2023.168690] [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: 10/16/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023]
Abstract
Mercury (Hg) is a global pollutant showing potent toxicity to living organisms. The transformations of Hg are critical to global Hg cycling and Hg exposure risks, considering Hg mobilities and toxicities vary depending on Hg speciation. Though currently well understood in ambient environments, Hg transformations are inadequately explored in non-microbial organisms. The primary drivers of in vivo Hg transformations are far from clear, and the impacts of these processes on global Hg cycling and Hg associated health risks are not well understood. This hinders a comprehensive understanding of global Hg cycling and the effective mitigation of Hg exposure risks. Here, we focused on Hg transformations in non-microbial organisms, particularly algae, plants, and animals. The process of Hg oxidation/reduction and methylation/demethylation in organisms were reviewed since these processes are the key transformations between the dominant Hg species, i.e., elemental Hg (Hg0), divalent inorganic Hg (IHgII), and methylmercury (MeHg). By summarizing the current knowledge of Hg transformations in organisms, we proposed the potential yet overlooked drivers of these processes, along with potential challenges that hinder a full understanding of in vivo Hg transformations. Knowledge summarized in this review would help achieve a comprehensive understanding of the fate and toxicity of Hg in organisms, providing a basis for predicting Hg cycles and mitigating human exposure.
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Affiliation(s)
- Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Zhuoran Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Mengjie Wu
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Yang Zhou
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
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2
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de Oliveira AT, Rodrigues PDA, Ramos Filho AM, Gomes MFDS, Liebl ARDS, de Pinho JV, Aride PHR, Conte-Junior CA. Levels of Total Mercury and Health Risk Assessment of Consuming Freshwater Stingrays (Chondrichthyes: Potamotrygoninae) of the Brazilian Amazon. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:6990. [PMID: 37947548 PMCID: PMC10647567 DOI: 10.3390/ijerph20216990] [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: 09/06/2023] [Revised: 10/22/2023] [Accepted: 10/25/2023] [Indexed: 11/12/2023]
Abstract
Mercury is an element with potential risk to fish and those who consume it. Thus, this study aimed to determine the levels of total mercury (THg), carry out a health risk assessment related to the consumption of the freshwater stingrays Potamotrygon motoro, and determine the physical and chemical properties of the water where stingrays occur. Stingrays of the species P. motoro were obtained from the Amazon River, and samples of the animals' musculature were collected to determine THg levels. Risk assessment was conducted using pre-established formulas of estimated monthly intake (EMI), maximum monthly intake rate (IRmm), and hazard quotient (HQ). Three population scenarios were evaluated, considering both sexes and differences between rural and urban areas. There was no relationship between weight and THg concentration nor between total length and THg concentration. Higher EMI values were observed in rural children; for the IRmm, male children had the lowest consumption levels. For the hazard quotient, there was a similarity between the three age groups when comparing the male and female sexes. In addition, the representatives of the rural area always had lower values than the urban area. Freshwater stingrays, like other elasmobranchs, can be crucial animal species because they act as sentinels in studies that assess harmful chemicals like mercury.
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Affiliation(s)
- Adriano Teixeira de Oliveira
- Animal Morphophysiology Laboratory, Academic Department of Teacher Training (DAEF), Federal Institute of Education, Science and Technology of Amazonas (IFAM), Manaus Centro Campus (CMC), Manaus 69020-120, AM, Brazil; (M.F.d.S.G.); (A.R.d.S.L.); (P.H.R.A.)
- Graduate Program in Animal Science and Fisheries Resources (PPGCARP), Faculty of Agricultural Sciences (FCA), Federal University of Amazonas (UFAM), University Campus, Manaus 69077-000, AM, Brazil
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-598, RJ, Brazil; (P.d.A.R.); (A.M.R.F.); (J.V.d.P.); (C.A.C.-J.)
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
| | - Paloma de Almeida Rodrigues
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-598, RJ, Brazil; (P.d.A.R.); (A.M.R.F.); (J.V.d.P.); (C.A.C.-J.)
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
| | - Alexandre Mendes Ramos Filho
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-598, RJ, Brazil; (P.d.A.R.); (A.M.R.F.); (J.V.d.P.); (C.A.C.-J.)
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
| | - Maria Fernanda da Silva Gomes
- Animal Morphophysiology Laboratory, Academic Department of Teacher Training (DAEF), Federal Institute of Education, Science and Technology of Amazonas (IFAM), Manaus Centro Campus (CMC), Manaus 69020-120, AM, Brazil; (M.F.d.S.G.); (A.R.d.S.L.); (P.H.R.A.)
- Graduate Program in Animal Science and Fisheries Resources (PPGCARP), Faculty of Agricultural Sciences (FCA), Federal University of Amazonas (UFAM), University Campus, Manaus 69077-000, AM, Brazil
| | - Ariany Rabello da Silva Liebl
- Animal Morphophysiology Laboratory, Academic Department of Teacher Training (DAEF), Federal Institute of Education, Science and Technology of Amazonas (IFAM), Manaus Centro Campus (CMC), Manaus 69020-120, AM, Brazil; (M.F.d.S.G.); (A.R.d.S.L.); (P.H.R.A.)
| | - Júlia Vianna de Pinho
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-598, RJ, Brazil; (P.d.A.R.); (A.M.R.F.); (J.V.d.P.); (C.A.C.-J.)
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
- Graduate Program in Sanitary Surveillance (PPGVS), National Institute of Health Quality Control (INCQS), Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro 21040-900, RJ, Brazil
- National Institute of Health Quality Control, Oswaldo Cruz Foundation, Rio de Janeiro 21040-900, RJ, Brazil
| | - Paulo Henrique Rocha Aride
- Animal Morphophysiology Laboratory, Academic Department of Teacher Training (DAEF), Federal Institute of Education, Science and Technology of Amazonas (IFAM), Manaus Centro Campus (CMC), Manaus 69020-120, AM, Brazil; (M.F.d.S.G.); (A.R.d.S.L.); (P.H.R.A.)
| | - Carlos Adam Conte-Junior
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-598, RJ, Brazil; (P.d.A.R.); (A.M.R.F.); (J.V.d.P.); (C.A.C.-J.)
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
- Graduate Program in Sanitary Surveillance (PPGVS), National Institute of Health Quality Control (INCQS), Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro 21040-900, RJ, Brazil
- National Institute of Health Quality Control, Oswaldo Cruz Foundation, Rio de Janeiro 21040-900, RJ, Brazil
- Graduate Program in Veterinary Hygiene (PPGHV), Faculty of Veterinary Medicine, Fluminense Federal University (UFF), Vital Brazil Filho, Niteroi 24220-000, RJ, Brazil
- Graduate Program in Food Science (PPGCAL), Institute of Chemistry (IQ), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
- Graduate Program in Chemistry (PGQu), Institute of Chemistry (IQ), Federal University of Rio de Janeiro (UFRJ), University City, Rio de Janeiro 21941-909, RJ, Brazil
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Yu Y, Li Z, Liu Y, Wang F, Liu Y, Zhao J, Li Y, Gao Y, Zhu N. Roles of plant-associated microorganisms in regulating the fate of Hg in croplands: A perspective on potential pathways in maintaining sustainable agriculture. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 834:155204. [PMID: 35421489 DOI: 10.1016/j.scitotenv.2022.155204] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/06/2022] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
In heavy metal-contaminated croplands, plant-associated microorganisms play important roles in the adaptation of crops to heavy metals. Plant-associated microbes can interact with Hg and stimulate plant resistance to Hg toxicity, which is crucial for impeding Hg accumulation along the food chain. The roles of rhizosphere microorganisms for the improvement of plant growth and Hg resistance have drawn great research attention. However, the interactions among plant-endophyte-Hg have been neglected although they might be important for in vivo Hg detoxification. In this study, we systematically summarized 1) the roles of plant-associated microorganisms in Hg detoxification and plant growth, 2) Hg methylation and demethylation driven by plant-associated microbes, 3) the relationships between plant-associated microbes and Hg biogeochemical cycling. The possible mechanisms underlying crop-endophyte-Hg interactions were discussed, although limited studies on this aspect are available to date. The challenges and perspectives of plant-endophytes in dampening Hg phytotoxicity and controlling Hg accumulation in croplands were proposed on the basis of the present knowledge. Taken together, this work provides evidence for further understanding the interactions between soil-plant-endophyte-Hg systems and as well as new interpretations and perspectives into regulating the fate of Hg in croplands.
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Affiliation(s)
- Yue Yu
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China; State Environmental Protection Key Laboratory of Food Chain Pollution Control, Beijing Technology and Business University, Beijing 100048, China
| | - Zhanming Li
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China; State Environmental Protection Key Laboratory of Food Chain Pollution Control, Beijing Technology and Business University, Beijing 100048, China; School of Environment, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Yonghua Liu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, & CAS-HKU Joint Laboratory of Metallomics on Health and Environment, & Beijing Metallomics Facility, & National Consortium for Excellence in Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030000, Shanxi, China
| | - Fang Wang
- State Environmental Protection Key Laboratory of Food Chain Pollution Control, Beijing Technology and Business University, Beijing 100048, China
| | - Yurong Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiating Zhao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, & CAS-HKU Joint Laboratory of Metallomics on Health and Environment, & Beijing Metallomics Facility, & National Consortium for Excellence in Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yufeng Li
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, & CAS-HKU Joint Laboratory of Metallomics on Health and Environment, & Beijing Metallomics Facility, & National Consortium for Excellence in Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yuxi Gao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, & CAS-HKU Joint Laboratory of Metallomics on Health and Environment, & Beijing Metallomics Facility, & National Consortium for Excellence in Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Nali Zhu
- School of Environment, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.
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Shi J, Zhang B, Liu J, Fang Y, Wang A. Spatiotemporal dynamics in microbial communities mediating biogeochemical cycling of nutrients across the Xiaowan Reservoir in Lancang River. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 813:151862. [PMID: 34826492 DOI: 10.1016/j.scitotenv.2021.151862] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/27/2021] [Accepted: 11/17/2021] [Indexed: 06/13/2023]
Abstract
Microbes drive biogeochemical cycles of nutrients controlling water quality in freshwater ecosystems, yet little is known regarding how spatiotemporal variation in the microbial community affects this ecosystem-level functional processes to resist perturbations. Here we examined spatiotemporal dynamics of microbial communities in paired stratified water columns and sediments collected from the Xiaowan Reservoir of Lancang-Mekong River over a year long period. Results highlighted distinctive spatiotemporal patterns of microbial communities in water columns mainly driven by sulfate, dissolved oxygen, nitrate and temperature, whilst sediment communities only showed a seasonal variation pattern governed by pH, reduced inorganic sulfur, sulfate, organic matter and total nitrogen. Microbial co-occurrence networks revealed the succession of keystone taxa in both water columns and sediments, reflecting core ecological functions in response to altered environmental conditions. Specifically, in shallow water, keystone nitrogen fixers and denitrifiers were responsible for providing nitrogen nutrients in summer, while recalcitrant substance degraders likely supplied microbially available organic matters to maintain ecosystem stability in winter. But in deep water, methane oxidation was the critical process linked to microbial-mediated cycle of carbon, nitrogen and sulfur. In addition, carbon metabolism and mercury methylation mediated by sulfate reducers, denitrifiers and nitrogen fixers were core functioning features of sediments in summer and winter, respectively. This work expands our knowledge of the importance of keystone taxa in maintaining stability of reservoir ecosystems under changing environments, providing new perspectives for water resource conservation and management.
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Affiliation(s)
- Jiaxin Shi
- School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China
| | - Baogang Zhang
- School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China
| | - Jun Liu
- State Key Laboratory of Agricultural Microbiology, State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
| | - Yun Fang
- School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan 430205, China
| | - Aijie Wang
- State Key Laboratory of Urban Water Resources and Environments, Harbin Institute of Technology, Harbin 150090, China
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5
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Wang J, Dai J, Chen G, Jiang F. Role of sulfur biogeochemical cycle in mercury methylation in estuarine sediments: A review. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:126964. [PMID: 34523493 DOI: 10.1016/j.jhazmat.2021.126964] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 07/26/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Estuaries are sinks for mercury, in which the most toxic mercury form, neurotoxic methylmercury (MeHg), is produced by mercury methylators and accumulates in estuarine sediments. In the same area, the microbial sulfur cycle is triggered by sulfate-reducing bacteria (SRB), which is considered as the main mercury methylator. In this review, we analyzed the sulfur and mercury speciation in sediments from 70 estuaries globally. Abundant mercury and sulfur species were found in the global estuarine sediments. Up to 727 μg THg/g dw and 880 ng MeHg/g dw were found in estuarine sediments, showing the serious risk of mercury to aquatic ecological systems. Significant correlations between sulfur and MeHg concentrations were discovered. Especially, the porewater sulfate concentration positively correlated to MeHg production. The sulfur cycle affects MeHg formation via activating mercury methylator activities and limiting mercury bioavailability, leading to promote or inhibit MeHg formation at different sulfur speciation concentrations. These results suggest that sulfur biogeochemical cycle plays an important role in mercury methylation in estuarine sediments, and the effect of the sulfur cycle on mercury methylation deserves to be further explored in future research.
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Affiliation(s)
- Jinting Wang
- Department of Civil and Environmental Engineering, Water Technology Lab, Hong Kong Branch of Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ji Dai
- Department of Civil and Environmental Engineering, Water Technology Lab, Hong Kong Branch of Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
| | - Guanghao Chen
- Department of Civil and Environmental Engineering, Water Technology Lab, Hong Kong Branch of Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Feng Jiang
- Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, School of Environmental Science & Engineering, Sun Yat-sen University, Guangzhou, China.
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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: 14] [Impact Index Per Article: 3.5] [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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Burke SM, Zimmerman CE, Laske SM, Koch JC, Derry AM, Guernon S, Branfireun BA, Swanson HK. Fish growth rates and lake sulphate explain variation in mercury levels in ninespine stickleback (Pungitius pungitius) on the Arctic Coastal Plain of Alaska. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 743:140564. [PMID: 32758814 DOI: 10.1016/j.scitotenv.2020.140564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Mercury concentrations in freshwater food webs are governed by complex biogeochemical and ecological interactions that spatially vary and are often mediated by climate. The Arctic Coastal Plain of Alaska (ACP) is a heterogeneous, lake-rich landscape where variability in mercury accumulation is poorly understood. Earlier research indicated that the level of catchment influence on lakes varied spatially on the ACP, and affected mercury accumulation in lake sediments. This work sought to determine drivers of spatial variation in mercury accumulation in lake food webs on the ACP. Three lakes that were a priori identified as "high catchment influence" (Reindeer Camp region) and three lakes that were a priori identified as "low catchment influence" (Atqasuk region) were sampled, and variability in water chemistry, food web ecology, and mercury accumulation was investigated. Among-lake differences in ninespine stickleback (Pungitius pungitius) length-adjusted methylmercury concentrations were significantly explained by sulphate concentration in lake water, a tracer of catchment runoff input. This effect was mediated by fish growth, which had no pattern between regions. Together, lake water sulphate concentration and fish age-at-size (proxy for growth) accounted for nearly all of the among-lake variability in length-adjusted methylmercury concentrations in stickleback (R2adj = 0.94, p < 0.01). The percentage of total mercury as methylmercury (a proxy for net Hg methylation) was higher in sediments of more autochthonous, "low catchment influence" lakes (p < 0.05), and in the periphyton of more allochthonous, "high catchment influence" lakes (p < 0.05). The results indicate that dominant sources of primary production (littoral macrophyte/biofilm vs. pelagic phytoplankton) and food web structure (detrital vs. grazing) are regulated by catchment characteristics on the ACP, and that this ultimately influences the amount of methylmercury in the aquatic food web. These results have important implications for predicting future mercury concentrations in fish in lakes where fish growth rates and catchment inputs may change in response to a changing climate.
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Affiliation(s)
- S M Burke
- Department of Biology and Water Institute, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L 3G1, Canada; Environment and Climate Change Canada (ECCC), Aquatic Contaminants Research Division, 867 Lakeshore Rd., Burlington, ON L7S 1A1, Canada.
| | - C E Zimmerman
- U. S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA
| | - S M Laske
- U. S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA
| | - J C Koch
- U. S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA
| | - A M Derry
- Département des sciences biologiques, Université du Québec à Montréal (UQAM), P.O. Box 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - S Guernon
- Département des sciences biologiques, Université du Québec à Montréal (UQAM), P.O. Box 8888, Succ. Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - B A Branfireun
- Western University, Department of Biological Sciences, London, Ontario N6A 3K7, Canada
| | - H K Swanson
- Department of Biology and Water Institute, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L 3G1, Canada
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Schwartz GE, Olsen TA, Muller KA, Brooks SC. Ecosystem Controls on Methylmercury Production by Periphyton Biofilms in a Contaminated Stream: Implications for Predictive Modeling. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:2426-2435. [PMID: 31365146 DOI: 10.1002/etc.4551] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/12/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
Periphyton biofilms produce a substantial fraction of the overall monomethylmercury (MMHg) flux in East Fork Poplar Creek, an industrially contaminated, freshwater creek in Oak Ridge, Tennessee. We examined periphyton MMHg production across seasons, locations, and light conditions using mercury stable isotopes. Methylation and demethylation rate potentials (km, trans av and kd, trans av , respectively) were calculated using a transient availability kinetic model. Light exposure and season were significant predictors of km, trans av , with greater values in full light exposure and in the summer. Season, light exposure, and location were significant predictors of kd, trans av , which was highest in dark conditions, in the spring, and at the upstream location. Light exposure was the controlling factor for net MMHg production, with positive production for periphyton grown under full light exposure and net demethylation for periphyton grown in the dark. Ambient MMHg and km, trans av were significantly correlated. Transient availability rate potentials were 15 times higher for km and 9 times higher for kd compared to full availability rate potentials (km, full av and kd, full av ) calculated at 1 d. No significant model for the prediction of km, full av or kd, full av could be constructed using light, season, and location. In addition, there were no significant differences among treatments for the full availability km, full av , kd, full av , or net MMHg calculated using the full availability rate potentials. km, full av was not correlated with ambient MMHg concentrations. The present results underscore the importance of applying transient availability kinetics to MMHg production data when estimating MMHg production potential and flux. Environ Toxicol Chem 2019;38:2426-2435. © 2019 SETAC.
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Affiliation(s)
- Grace E Schwartz
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Todd A Olsen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Katherine A Muller
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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9
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Lázaro WL, Díez S, Bravo AG, da Silva CJ, Ignácio ÁRA, Guimaraes JRD. Cyanobacteria as regulators of methylmercury production in periphyton. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:723-729. [PMID: 30861408 DOI: 10.1016/j.scitotenv.2019.02.233] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/18/2019] [Accepted: 02/15/2019] [Indexed: 06/09/2023]
Abstract
Biotic mercury (Hg) methylation appears to depend on factors such as microbial activity and the concentration and bioavailability of Hg2+ to the Hg-methylating organisms. Recently, the presence of cyanobacteria has been linked with high methylmercury (MeHg) concentrations. The aim of this work was to test MeHg production in microcosms, in relation to the amount of periphytic cyanobacteria, dissolved organic matter (DOM) and phosphorus concentrations, as well as periphytic primary production rates. Water and periphyton samples were collected for cultivation and isolation of cyanobacteria from the Guaporé River floodplain, Brazil. We cultivated the periphyton in microcosms with different concentrations of cyanobacteria, total phosphorus and DOM. The highest net MeHg production (6.8 to 24.6% of added Hg d-1) occurred in the microcosm with added cyanobacteria, followed by microcosms with added phosphorus (6.1 to 11.4%) and added DOM (6.4 to 9.1%). Positive correlations were found between MeHg production, addition of cyanobacteria, phosphorus and DOM and periphytic primary productivity. Our results bring the first direct experimental evidence of the relevance of cyanobacteria and primary production as regulators of MeHg production in periphyton. These findings have numerous implications for the management of natural and engineered wetlands.
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Affiliation(s)
- Wilkinson L Lázaro
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil. Avenida Santos Dummont, Cidade Universitária, 78200-000 Cáceres, MT, Brazil.
| | - Sergi Díez
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research (IDAEA-CSIC). C/Jordi Girona, 18-26, 08034 Barcelona, Spain.
| | - Andrea G Bravo
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research (IDAEA-CSIC). C/Jordi Girona, 18-26, 08034 Barcelona, Spain.
| | - Carolina J da Silva
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil. Avenida Santos Dummont, Cidade Universitária, 78200-000 Cáceres, MT, Brazil; Rede Bionorte, Doutorado em Biodiversidade e Biotecnologia da Amazônia Legal. Avenida Fernando Correa da Costa, 2.367, Boa Esperança, 78060-900, Cuiabá, Brazil.
| | - Áurea R A Ignácio
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil. Avenida Santos Dummont, Cidade Universitária, 78200-000 Cáceres, MT, Brazil.
| | - Jean R D Guimaraes
- Laboratório de Traçadores, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ). Av. Carlos Chagas Filho 373 Bloco G, CCS, Cidade Universitária, 21941-902, Rio de Janeiro, RJ, Brazil.
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Gilmour C, Bell JT, Soren AB, Riedel G, Riedel G, Kopec AD, Bodaly RA. Distribution and biogeochemical controls on net methylmercury production in Penobscot River marshes and sediment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 640-641:555-569. [PMID: 29864668 DOI: 10.1016/j.scitotenv.2018.05.276] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 05/18/2018] [Accepted: 05/22/2018] [Indexed: 05/28/2023]
Abstract
The distribution of mercury and methylmercury (MeHg) in sediment, mudflats, and marsh soils of the Hg-contaminated tidal Penobscot River was investigated, along with biogeochemical controls on production. Average total Hg in surface samples (0-3 cm) ranged from 100 to 1200 ng/g; average MeHg ranged from 5 to 50 ng/g. MeHg was usually highest at or near the surface except in highly mobile mudflats. Although total Hg concentrations in the Penobscot are elevated, it is the accumulation of MeHg that stands out in comparison to other ecosystems. Surface soils in the large Mendall Marsh, about 17 km downstream from the contamination source, contained particularly high %MeHg (averaging 8%). In Mendall marsh soil porewaters, MeHg often accounted for more than half of total Hg. Salt marshes are areas of particular concern in the Penobscot River, for they are depositional environments for a Hg-contaminated mobile pool of river sediment, hot spots for net MeHg production, and sources of risk to marsh animals. We hypothesized that exceptionally low mercury partitioning between the solid and aqueous phases (with log Kd averaging ~4.5) drives high MeHg in Penobscot marshes. The co-occurrence of iron and sulfide in filtered soil porewaters, sometimes both above 100 μM, suggests the presence of nanoparticulate and/or colloidal metal sulfides. These colloids may be stabilized by high concentrations of aromatic and potentially sulfurized dissolved organic matter (DOM) in marsh soils. Thus, Hg in Penobscot marsh soils appears to be in a highly available for microbial methylation through the formation of DOM-associated HgS complexes. Additionally, low partitioning of MeHg to marsh soils suggests high MeHg bioavailability to animals. Overall, drivers of high MeHg in Penobscot marshes include elevated Hg in soils, low partitioning of Hg to solids, high Hg bioavailability for methylation, rapidly shifting redox conditions in surface marsh soils, and high rates of microbial activity.
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Affiliation(s)
- Cynthia Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States.
| | - James Tyler Bell
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | - Ally Bullock Soren
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | - Georgia Riedel
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | - Gerhardt Riedel
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 20657, United States
| | | | - R A Bodaly
- Penobscot River Mercury Study, Bangor, ME, US.
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11
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Evidence of Mercury Methylation and Demethylation by the Estuarine Microbial Communities Obtained in Stable Hg Isotope Studies. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15102141. [PMID: 30274240 PMCID: PMC6210349 DOI: 10.3390/ijerph15102141] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/25/2018] [Accepted: 09/25/2018] [Indexed: 11/17/2022]
Abstract
Microbial activity is a critical factor controlling methylmercury formation in aquatic environments. Microbial communities were isolated from sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and differentiated according to their dependence on oxygen into three groups: aerobic, anaerobic, and sulphate-reducing microbial communities. Their potential to methylate mercury and demethylate methylmercury was evaluated through incubation with isotope-enriched Hg species (199HgCl and CH3201HgCl). The results showed that the isolated microbial communities are actively involved in methylation and demethylation processes. The production of CH3199Hg was positively correlated with sulphate-reducing microbial communities, methylating up to 0.07% of the added 199Hg within 48 h of incubation. A high rate of CH3201Hg degradation was observed and >20% of CH3201Hg was transformed. Mercury removal of inorganic forms was also observed. The results prove the simultaneous occurrence of microbial methylation and demethylation processes and indicate that microorganisms are mainly responsible for methylmercury formation and accumulation in the polluted Tagus Estuary.
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12
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Lázaro WL, Díez S, da Silva CJ, Ignácio ÁRA, Guimarães JRD. Seasonal changes in peryphytic microbial metabolism determining mercury methylation in a tropical wetland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 627:1345-1352. [PMID: 30857098 DOI: 10.1016/j.scitotenv.2018.01.186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/08/2018] [Accepted: 01/18/2018] [Indexed: 06/09/2023]
Abstract
Mercury (Hg) methylation, a key process in the biogeochemical cycle of Hg, is mainly attributed to sulfate-reducing bacteria and methanogenic Archaea. However, environmental regulation by these groups has not yet been ascertained in tropical environments, especially in respect to the seasonal flood flooding. This work evaluated the variation of net methylmercury production potential in relation to biological characteristics of the periphyton, environmental factors, and flood pulse seasons. Our results indicate that there is a seasonal change between metabolic groups as main Hg methylators, sulfate-reducing bacteria in the dry season and methanogenic Archaea in the flood season. In addition, there was a positive relationship between dissolved organic carbon (DOC), phosphorus, cyanobacteria biovolume, and periphytic Hg methylation potential. These results shed a new light on MeHg production plasticity, mediated by landscape and flood pulses in tropical wetlands, as well as on ecological relationships within the periphyton.
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Affiliation(s)
- Wilkinson L Lázaro
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brazil.
| | - Sergi Díez
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain.
| | - Carolina J da Silva
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brazil; Rede Bionorte, Doutorado em Biodiversidade e Biotecnologia da Amazônia Legal, Brazil
| | - Áurea R A Ignácio
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brazil
| | - Jean R D Guimarães
- Laboratório de Traçadores. Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Brazil
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13
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Bravo AG, Zopfi J, Buck M, Xu J, Bertilsson S, Schaefer JK, Poté J, Cosio C. Geobacteraceae are important members of mercury-methylating microbial communities of sediments impacted by waste water releases. ISME JOURNAL 2018; 12:802-812. [PMID: 29321692 PMCID: PMC5864163 DOI: 10.1038/s41396-017-0007-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/29/2017] [Accepted: 10/18/2017] [Indexed: 11/16/2022]
Abstract
Microbial mercury (Hg) methylation in sediments can result in bioaccumulation of the neurotoxin methylmercury (MMHg) in aquatic food webs. Recently, the discovery of the gene hgcA, required for Hg methylation, revealed that the diversity of Hg methylators is much broader than previously thought. However, little is known about the identity of Hg-methylating microbial organisms and the environmental factors controlling their activity and distribution in lakes. Here, we combined high-throughput sequencing of 16S rRNA and hgcA genes with the chemical characterization of sediments impacted by a waste water treatment plant that releases significant amounts of organic matter and iron. Our results highlight that the ferruginous geochemical conditions prevailing at 1–2 cm depth are conducive to MMHg formation and that the Hg-methylating guild is composed of iron and sulfur-transforming bacteria, syntrophs, and methanogens. Deltaproteobacteria, notably Geobacteraceae, dominated the hgcA carrying communities, while sulfate reducers constituted only a minor component, despite being considered the main Hg methylators in many anoxic aquatic environments. Because iron is widely applied in waste water treatment, the importance of Geobacteraceae for Hg methylation and the complexity of Hg-methylating communities reported here are likely to occur worldwide in sediments impacted by waste water treatment plant discharges and in iron-rich sediments in general.
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Affiliation(s)
- Andrea G Bravo
- Limnology and Science for Life Laboratory, Uppsala University, Uppsala, SE-75236, Sweden
| | - Jakob Zopfi
- Aquatic and Stable Isotope Biogeochemistry, University of Basel, Basel, CH-4056, Switzerland
| | - Moritz Buck
- Limnology and Science for Life Laboratory, Uppsala University, Uppsala, SE-75236, Sweden
| | - Jingying Xu
- Limnology and Science for Life Laboratory, Uppsala University, Uppsala, SE-75236, Sweden
| | - Stefan Bertilsson
- Limnology and Science for Life Laboratory, Uppsala University, Uppsala, SE-75236, Sweden
| | - Jeffra K Schaefer
- Environmental Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - John Poté
- Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, CH-1205, Switzerland
| | - Claudia Cosio
- Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, CH-1205, Switzerland. .,Unité Stress Environnementaux et BIOSurveillance des Milieux Aquatiques UMR-I 02 (SEBIO), Université de Reims Champagne Ardenne, Reims, F-51687, France.
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14
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Yang C, Wang Q, Simon PN, Liu J, Liu L, Dai X, Zhang X, Kuang J, Igarashi Y, Pan X, Luo F. Distinct Network Interactions in Particle-Associated and Free-Living Bacterial Communities during a Microcystis aeruginosa Bloom in a Plateau Lake. Front Microbiol 2017; 8:1202. [PMID: 28713340 PMCID: PMC5492469 DOI: 10.3389/fmicb.2017.01202] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/13/2017] [Indexed: 12/23/2022] Open
Abstract
Particle-associated bacteria (PAB) and free-living bacteria (FLB) from aquatic environments during phytoplankton blooms differ in their physical distance from algae. Both the interactions within PAB and FLB community fractions and their relationship with the surrounding environmental properties are largely unknown. Here, by using high-throughput sequencing and network-based analyses, we compared the community and network characteristics of PAB and FLB from a plateau lake during a Microcystis aeruginosa bloom. Results showed that PAB and FLB differed significantly in diversity, structure and microbial connecting network. PAB communities were characterized by highly similar bacterial community structure in different sites, tighter network connections, important topological roles for the bloom-causing M. aeruginosa and Alphaproteobacteria, especially for the potentially nitrogen-fixing (Pleomorphomonas) and algicidal bacteria (Brevundimonas sp.). FLB communities were sensitive to the detected environmental factors and were characterized by significantly higher bacterial diversity, less connectivity, larger network size and marginal role of M. aeruginosa. In both networks, covariation among bacterial taxa was extensive (>88% positive connections), and bacteria potentially affiliated with biogeochemical cycling of nitrogen (i.e., denitrification, nitrogen-fixation and nitrite-oxidization) were important in occupying module hubs, such as Meganema, Pleomorphomonas, and Nitrospira. These findings highlight the importance of considering microbial network interactions for the understanding of blooms.
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Affiliation(s)
- Caiyun Yang
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Qi Wang
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Paulina N Simon
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Jinyu Liu
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Lincong Liu
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Xianzhu Dai
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Xiaohui Zhang
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Jialiang Kuang
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Plant Resources and Conservation of Guangdong Higher Education Institutes, College of Ecology and Evolution, Sun Yat-sen UniversityGuangzhou, China
| | - Yasuo Igarashi
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
| | - Xuejun Pan
- Faculty of Environmental Science and Engineering, Kunming University of Science and TechnologyKunming, China
| | - Feng Luo
- Research Center of Bioenergy and Bioremediation, Southwest UniversityChongqing, China
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15
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Lanza WG, Achá D, Point D, Masbou J, Alanoca L, Amouroux D, Lazzaro X. Association of a Specific Algal Group with Methylmercury Accumulation in Periphyton of a Tropical High-Altitude Andean Lake. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2017; 72:1-10. [PMID: 27822581 DOI: 10.1007/s00244-016-0324-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 10/21/2016] [Indexed: 06/06/2023]
Abstract
Periphyton relevance for methylmercury (MeHg) production and accumulation are now well known in aquatic ecosystems. Sulfate-reducing bacteria and other microbial groups were identified as the main MeHg producers, but the effect of periphyton algae on the accumulation and transfer of MeHg to the food web remains little studied. Here we investigated the role of specific groups of algae on MeHg accumulation in the periphyton of Schoenoplectus californicus ssp. (Totora) and Myriophyllum sp. in Uru Uru, a tropical high-altitude Bolivian lake with substantial fishing and mining activities accruing around it. MeHg concentrations were most strongly related to the cell abundance of the Chlorophyte genus Oedogonium (r 2 = 0.783, p = 0.0126) and to no other specific genus despite the presence of other 34 genera identified. MeHg was also related to total chlorophyll-a (total algae) (r 2 = 0.675, p = 0.0459), but relations were more significant with chlorophyte cell numbers, chlorophyll-b (chlorophytes), and chlorophyll-c (diatoms and dinoflagellates) (r 2 = 0.72, p = 0.028, r 2 = 0.744, p = 0.0214, and r 2 = 0.766, p = 0.0161 respectively). However, Oedogonium explains most variability of chlorophytes and chlorophyll-c (r 2 = 0.856, p = < 0.001 and r 2 = 0.619, p = 0.002, respectively), suggesting it is the most influential group for MeHg accumulation and periphyton algae composition at this particular location and given time.
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Affiliation(s)
- William G Lanza
- Carrera de Biología, Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, La Paz, Bolivia
| | - Darío Achá
- Carrera de Biología, Unidad de Calidad Ambiental, Instituto de Ecología, Universidad Mayor de San Andrés, La Paz, Bolivia.
| | - David Point
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
| | - Jeremy Masbou
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
| | - Lucia Alanoca
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
- LCABIE-IPREM, UMR 5254 - CNRS, Université de Pau et des Pays de l'Adour, 64053, Pau, France
| | - David Amouroux
- Institut de Recherche pour le Dev́eloppement, Université de Toulouse III, CNRS, IRD, 31400, Toulouse, France
- LCABIE-IPREM, UMR 5254 - CNRS, Université de Pau et des Pays de l'Adour, 64053, Pau, France
| | - Xavier Lazzaro
- Unité Mixte de Recherche Biologie des Organismes et Ecosystèmes Aquatiques (BOREA UMR 7208), Muséum National d'Histoire Naturelle, Université Pierre et Marie Curie, Université de Caen Basse-Normandie, Centre National de la Recherche Scientifique, Institut de Recherche pour le Développement-207; CP53, 61 rue Buffon, 75005, Paris, France
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16
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Lázaro WL, Díez S, da Silva CJ, Ignácio ÁRA, Guimarães JRD. Waterscape determinants of net mercury methylation in a tropical wetland. ENVIRONMENTAL RESEARCH 2016; 150:438-445. [PMID: 27376931 DOI: 10.1016/j.envres.2016.06.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/30/2016] [Accepted: 06/17/2016] [Indexed: 06/06/2023]
Abstract
The periphyton associated with freshwater macrophyte roots is the main site of Hg methylation in different wetland environments in the world. The aim of this study was to test the use of connectivity metrics of water bodies, in the context of patches, in a tropical waterscape wetland (Guapore River, Amazonia, Brazil) as a predictor of potential net methylmercury (MeHg) production by periphyton communities. We sampled 15 lakes with different patterns of lateral connectivity with the main river channel, performing net mercury methylation potential tests in incubations with local water and Eichhornia crassipes root-periphyton samples, using (203)HgCl2 as a tracer. Physico-chemical variables, landscape data (morphological characteristics, land use, and lateral connection type of water bodies) using GIS resources and field data were analyzed with Generalized Additive Models (GAM). The net Me(203)Hg production (as % of total added (203)Hg) was expressive (6.2-25.6%) showing that periphyton is an important matrix in MeHg production. The model that best explained the variation in the net Me(203)Hg production (76%) was built by the variables: connection type, total phosphorus and dissolved organic carbon (DOC) in water (AICc=48.324, p=0.001). Connection type factor was the best factor to model fit (r(2)=0.32; p=0.008) and temporarily connected lakes had higher rates of net mercury methylation. Both DOC and total phosphorus showed positive significant covariation with the net methylation rates (r(2)=0.26; p=0.008 and r(2)=0.21; p=0.012 respectively). Our study suggests a strong relationship between rates of net MeHg production in this tropical area and the type of water body and its hydrological connectivity within the waterscape.
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Affiliation(s)
- Wilkinson L Lázaro
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil; Programa de Pós Graduação em Ecologia, Universidade Federal do Rio de Janeiro (UFRJ), Brasil.
| | - Sergi Díez
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Spain
| | - Carolina J da Silva
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil; Rede Bionorte, Doutorado em Biodiversidade e Biotecnologia da Amazônia Legal, Brasil
| | - Áurea R A Ignácio
- Centro de Estudos em Limnologia Biodiversidade e Etnobiologia do Pantanal, Universidade do Estado de Mato Grosso (UNEMAT), Brasil
| | - Jean R D Guimarães
- Laboratório de Traçadores. Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Brasil
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17
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Alanoca L, Amouroux D, Monperrus M, Tessier E, Goni M, Guyoneaud R, Acha D, Gassie C, Audry S, Garcia ME, Quintanilla J, Point D. Diurnal variability and biogeochemical reactivity of mercury species in an extreme high-altitude lake ecosystem of the Bolivian Altiplano. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:6919-6933. [PMID: 26676541 DOI: 10.1007/s11356-015-5917-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/02/2015] [Indexed: 06/05/2023]
Abstract
Methylation and demethylation represent major transformation pathways regulating the net production of methylmercury (MMHg). Very few studies have documented Hg reactivity and transformation in extreme high-altitude lake ecosystems. Mercury (Hg) species concentrations (IHg, MMHg, Hg°, and DMHg) and in situ Hg methylation (M) and MMHg demethylation (D) potentials were determined in water, sediment, floating organic aggregates, and periphyton compartments of a shallow productive Lake of the Bolivian Altiplano (Uru Uru Lake, 3686 m). Samples were collected during late dry season (October 2010) and late wet season (May 2011) at a north (NS) and a south (SS) site of the lake, respectively. Mercury species concentrations exhibited significant diurnal variability as influenced by the strong diurnal biogeochemical gradients. Particularly high methylated mercury concentrations (0.2 to 4.5 ng L(-1) for MMHgT) were determined in the water column evidencing important Hg methylation in this ecosystem. Methylation and D potentials range were, respectively, <0.1-16.5 and <0.2-68.3 % day(-1) and were highly variable among compartments of the lake, but always higher during the dry season. Net Hg M indicates that the influence of urban and mining effluent (NS) promotes MMHg production in both water (up to 0.45 ng MMHg L(-1) day(-1)) and sediment compartments (2.0 to 19.7 ng MMHg g(-1) day(-1)). While the sediment compartment appears to represent a major source of MMHg in this shallow ecosystem, floating organic aggregates (dry season, SS) and Totora's periphyton (wet season, NS) were found to act as a significant source (5.8 ng MMHg g(-1) day(-1)) and a sink (-2.1 ng MMHg g(-1) day(-1)) of MMHg, respectively. This work demonstrates that high-altitude productive lake ecosystems can promote MMHg formation in various compartments supporting recent observations of high Hg contents in fish and water birds.
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Affiliation(s)
- L Alanoca
- Géosciences Environnement Toulouse, UMR 5563-IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin, 31400, Toulouse, France
| | - D Amouroux
- Géosciences Environnement Toulouse, UMR 5563-IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin, 31400, Toulouse, France.
- Laboratoire de Chimie Analytique Bio-inorganique et Environnement, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Hélioparc Pau Pyrénées, 2, av. P. Angot, 64053, Pau cedex 9, France.
| | - M Monperrus
- Laboratoire de Chimie Analytique Bio-inorganique et Environnement, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Hélioparc Pau Pyrénées, 2, av. P. Angot, 64053, Pau cedex 9, France
| | - E Tessier
- Laboratoire de Chimie Analytique Bio-inorganique et Environnement, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Hélioparc Pau Pyrénées, 2, av. P. Angot, 64053, Pau cedex 9, France
| | - M Goni
- Equipe Environnement et Microbiologie, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - R Guyoneaud
- Equipe Environnement et Microbiologie, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - D Acha
- Laboratorio de Calidad Ambiental, Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota, casilla 3161, La Paz, Bolivia
| | - C Gassie
- Equipe Environnement et Microbiologie, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - S Audry
- Géosciences Environnement Toulouse, UMR 5563-IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin, 31400, Toulouse, France
| | - M E Garcia
- Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andres, Campus Universitario de Cota Cota, casilla 3161, La Paz, Bolivia
| | - J Quintanilla
- Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andres, Campus Universitario de Cota Cota, casilla 3161, La Paz, Bolivia
| | - D Point
- Géosciences Environnement Toulouse, UMR 5563-IRD UR 234, Université Paul Sabatier, 14 Avenue Edouard Belin, 31400, Toulouse, France
- Laboratorio de Calidad Ambiental, Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota, casilla 3161, La Paz, Bolivia
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18
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Figueiredo NL, Canário J, O'Driscoll NJ, Duarte A, Carvalho C. Aerobic Mercury-resistant bacteria alter Mercury speciation and retention in the Tagus Estuary (Portugal). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2016; 124:60-67. [PMID: 26461264 DOI: 10.1016/j.ecoenv.2015.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 09/28/2015] [Accepted: 10/01/2015] [Indexed: 06/05/2023]
Abstract
Aerobic mercury-resistant bacteria were isolated from the sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and one natural reserve area (Alcochete) in order to test their capacity to transform mercury. Bacterial species were identified using 16S rRNA amplification and sequencing techniques and the results indicate the prevalence of Bacillus sp. Resistance patterns to mercurial compounds were established by the determination of minimal inhibitory concentrations. Representative Hg-resistant bacteria were further tested for transformation pathways (reduction, volatilization and methylation) in cultures containing mercury chloride. Bacterial Hg-methylation was carried out by Vibrio fluvialis, Bacillus megaterium and Serratia marcescens that transformed 2-8% of total mercury into methylmercury in 48h. In addition, most of the HgR bacterial isolates showed Hg(2+)-reduction andHg(0)-volatilization resulting 6-50% mercury loss from the culture media. In summary, the results obtained under controlled laboratory conditions indicate that aerobic Hg-resistant bacteria from the Tagus Estuary significantly affect both the methylation and reduction of mercury and may have a dual face by providing a pathway for pollution dispersion while forming methylmercury, which is highly toxic for living organisms.
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Affiliation(s)
- Neusa L Figueiredo
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - João Canário
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Nelson J O'Driscoll
- Department of Earth & Environmental Sciences, Acadia University, K.C. Irving Environmental Science Center, 32 University Avenue, Wolfville, Nova Scotia, Canada
| | - Aida Duarte
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Cristina Carvalho
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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19
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Kucharzyk KH, Deshusses MA, Porter KA, Hsu-Kim H. Relative contributions of mercury bioavailability and microbial growth rate on net methylmercury production by anaerobic mixed cultures. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2015; 17:1568-77. [PMID: 26211614 PMCID: PMC4782143 DOI: 10.1039/c5em00174a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Monomethylmercury (MeHg) is produced in many aquatic environments by anaerobic microorganisms that take up and methylate inorganic forms of Hg(II). Net methylation of Hg(II) appears to be correlated with factors that affect the activity of the anaerobic microbial community and factors that increase the bioavailability of Hg(II) to these organisms. However, the relative importance of one versus the other is difficult to elucidate even though this information can greatly assist remediation efforts and risk assessments. Here, we investigated the effects of Hg speciation (dissolved Hg and nanoparticulate HgS) and microbial activity on the net production of MeHg using two mixed microbial cultures that were enriched from marine sediments under sulfate reducing conditions. The cultures were amended with dissolved Hg (added as a dissolved nitrate salt) and nanoparticulate HgS, and grown under different carbon substrate concentrations. The results indicated that net mercury methylation was the highest for cultures incubated in the greatest carbon substrate concentration (60 mM) compared to incubations with less carbon (0.6 and 6 mM), regardless of the form of mercury amended. Net MeHg production in cultures exposed to HgS nanoparticles was significantly slower than in cultures exposed to dissolved Hg; however, the difference diminished with slower growing cultures with low carbon addition (0.6 mM). The net Hg methylation rate was found to correlate with sulfate reduction rate in cultures exposed to dissolved Hg, while methylation rate was roughly constant for cultures exposed to nanoparticulate HgS. These results indicated a potential threshold of microbial productivity: below this point net MeHg production was limited by microbial activity, regardless of Hg bioavailability. Above this threshold of productivity, Hg speciation became a contributing factor towards net MeHg production.
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Affiliation(s)
- Katarzyna H Kucharzyk
- Duke University, Department of Civil and Environmental Engineering, 121 Hudson Hall, Durham, NC 27708, USA.
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20
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Bravo AG, Bouchet S, Guédron S, Amouroux D, Dominik J, Zopfi J. High methylmercury production under ferruginous conditions in sediments impacted by sewage treatment plant discharges. WATER RESEARCH 2015; 80:245-55. [PMID: 26005785 DOI: 10.1016/j.watres.2015.04.039] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 04/29/2015] [Accepted: 04/30/2015] [Indexed: 05/04/2023]
Abstract
Sewage treatment plants (STPs) are important point sources of mercury (Hg) to the environment. STPs are also significant sources of iron when hydrated ferric oxide (HFO) is used as a dephosphatation agent during water purification. In this study, we combined geochemical and microbiological characterization with Hg speciation and sediment amendments to evaluate the impact of STP's effluents on monomethylmercury (MMHg) production. The highest in-situ Hg methylation was found close to the discharge pipe in subsurface sediments enriched with Hg, organic matter, and iron. There, ferruginous conditions were prevailing with high concentrations of dissolved Fe(2+) and virtually no free sulfide in the porewater. Sediment incubations demonstrated that the high MMHg production close to the discharge was controlled by low demethylation yields. Inhibition of dissimilatory sulfate reduction with molybdate led to increased iron reduction rates and Hg-methylation, suggesting that sulfate-reducing bacteria (SRB) may not have been the main Hg methylators under these conditions. However, Hg methylation in sediments amended with amorphous Fe(III)-oxides was only slightly higher than control conditions. Thus, in addition to iron-reducing bacteria, other non-SRB most likely contributed to Hg methylation. Overall, this study highlights that sediments impacted by STP discharges can become local hot-spots for Hg methylation due to the combined inputs of i) Hg, ii) organic matter, which fuels bacterial activities and iii) iron, which keeps porewater sulfide concentration low and hence Hg bioavailable.
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Affiliation(s)
- Andrea G Bravo
- Institut F.-A. Forel, University of Geneva, Route de Suisse 10, CH-1290 Versoix, Genève, Switzerland.
| | - Sylvain Bouchet
- LCABIE-IPREM, UMR 5254 CNRS - Université de Pau et des Pays de l'Adour, Hélioparc, 64053 Pau, France
| | - Stéphane Guédron
- Institut F.-A. Forel, University of Geneva, Route de Suisse 10, CH-1290 Versoix, Genève, Switzerland; ISTerre, University Grenoble 1, IRD - UMR 5559 (IRD/UJF/CNRS) - BP 53, F-38041 Grenoble, France
| | - David Amouroux
- LCABIE-IPREM, UMR 5254 CNRS - Université de Pau et des Pays de l'Adour, Hélioparc, 64053 Pau, France
| | - Janusz Dominik
- Institut F.-A. Forel, University of Geneva, Route de Suisse 10, CH-1290 Versoix, Genève, Switzerland; Istituto di Scienze Marine - Consiglio Nazionale delle Ricercha, Castello 2737/F, I-30122 Venezia, Italy
| | - Jakob Zopfi
- Environmental Geosciences, University of Basel, Bernoullistrasse 30, CH-4056 Basel, Switzerland
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21
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Geochemical influences and mercury methylation of a dental wastewater microbiome. Sci Rep 2015; 5:12872. [PMID: 26271452 PMCID: PMC4642505 DOI: 10.1038/srep12872] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 06/29/2015] [Indexed: 01/19/2023] Open
Abstract
The microbiome of dental clinic wastewater and its impact on mercury methylation remains largely unknown. Waste generated during dental procedures enters the sewer system and contributes a significant fraction of the total mercury (tHg) and methyl mercury (MeHg) load to wastewater treatment facilities. Investigating the influence of geochemical factors and microbiome structure is a critical step linking the methylating microorganisms in dental wastewater (DWW) ecosystems. DWW samples from a dental clinic were collected over eight weeks and analyzed for geochemical parameters, tHg, MeHg and bacterio-toxic heavy metals. We employed bacterial fingerprinting and pyrosequencing for microbiome analysis. High concentrations of tHg, MeHg and heavy metals were detected in DWW. The microbiome was dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi and many unclassified bacteria. Significant correlations were found between the bacterial community, Hg levels and geochemical factors including pH and the predicted total amount (not fraction) of neutral Hg-sulfide species. The most prevalent known methylators included Desulfobulbus propionicus, Desulfovibrio desulfuricans, Desulfovibrio magneticus and Geobacter sulfurreducens. This study is the first to investigate the impact of high loads of Hg, MeHg and other heavy metals on the dental clinic wastewater microbiome, and illuminates the role of many known and unknown sulfate-reducing bacteria in Hg methylation.
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Bastos WR, Dórea JG, Bernardi JVE, Lauthartte LC, Mussy MH, Hauser M, Dória CRDC, Malm O. Mercury in muscle and brain of catfish from the Madeira river, Amazon, Brazil. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 118:90-97. [PMID: 25913362 DOI: 10.1016/j.ecoenv.2015.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 04/13/2015] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
The central nervous system is a critical target for Hg toxicity in all living organisms. Total Hg (THg) was determined in brain and muscle samples of 165 specimens of eight species of catfish (Brachyplatystoma filamentosum; Brachyplatystoma platynemum; Brachyplatystoma rousseauxii; Brachyplatystoma vaillantii; Phractocephalus hemiliopterus; Pseudoplatystoma punctifer; Pseudoplatystoma tigrinum; Zungaro zungaro) from the Madeira River, Brazilian Amazon. Despite the narrow range of Fishbase trophic level (4.2-4.6) the median THg concentrations ranged from 0.39 to 1.99mg/kg and from 0.03 to 0.29mg/kg respectively in muscle and brain from the studied species. Overall, the median concentration for all samples analyzed was 0.93mg/kg and 0.16mg/kg respectively in muscle and brain; most samples (76%) showed muscle Hg concentrations >0.5mg/kg. There were statistically significant THg differences between sex (female>males). The correlation between THg concentrations in muscle and brain was statistically significant (r=0.9170; p<0.0001). In the studied specimens, fish total length was significantly correlated with muscle (r=0.3163; p=0.0001) and brain (r=0.3039; p=0.0003) THg; however, fish age was negatively and significantly correlated (r=-0.2991; p=0.0012) with THg in muscle but not with THg in brain (r=-0.0190; p=0.8492). Amazonian catfish accumulate high levels of Hg in muscle and brain; however, brain-THg concentrations can be predicted from muscle-THg. Muscle-Hg in catfish can be a tool to detect brain-Hg concentrations associated with environmental Hg.
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Affiliation(s)
- Wanderley R Bastos
- Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Brazil
| | - José G Dórea
- Faculdade de Ciências da Saúde, Universidade de Brasília, Brazil.
| | | | | | - Marilia H Mussy
- Laboratório de Biogeoquímica Ambiental, Universidade Federal de Rondônia, Brazil; Laboratório de Ictiologia e Pesca, Universidade Federal de Rondônia, Brazil
| | - Marília Hauser
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
| | | | - Olaf Malm
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
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23
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Leclerc M, Planas D, Amyot M. Relationship between Extracellular Low-Molecular-Weight Thiols and Mercury Species in Natural Lake Periphytic Biofilms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:7709-7716. [PMID: 26011687 DOI: 10.1021/es505952x] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The uptake of mercury by microorganisms is a key step in the production of methylmercury, a biomagnifiable toxin. Mercury complexation by low-molecular-weight (LMW) thiols can affect its bioavailability and thus the production of methylmercury. Freshwater biofilms were sampled in the summer using artificial Teflon substrates submerged for over a year to allow natural community colonization in the littoral zone of a Boreal Shield lake. Inside biofilms, concentrations of different extracellular thiol species (thioglycolic acid, l-cysteine-l-glycine, cysteine, and glutathione) were up to 3 orders of magnitude greater than in the surrounding water column, potentially more readily controlling mercury speciation than in the water column. All biofilm thiols except thioglycolic acid were highly correlated to chlorophyll a, likely indicating an algal origin. Extracellular total mercury represented 3 ± 1% of all biofilm mercury and was preferentially found in the capsular fraction. Levels of LMW thiols of presumed algal origins were highly correlated with total mercury in the mobile colloidal fraction of biofilms. We propose that periphytic phototrophic microorganisms such as algae likely affect the bioavailability of mercury through the exudation of LMW thiols, and thus they may play a key role in the production of methylmercury in biofilms.
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Affiliation(s)
- Maxime Leclerc
- †GRIL, Département de Sciences Biologiques, Université de Montréal, C.P. 6128, Succursale Centre Ville, Montréal, Québec, Canada, H3C 3J7
| | - Dolors Planas
- ‡GRIL, Département de Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre Ville, Montréal, Québec, Canada H3C 3P8
| | - Marc Amyot
- †GRIL, Département de Sciences Biologiques, Université de Montréal, C.P. 6128, Succursale Centre Ville, Montréal, Québec, Canada, H3C 3J7
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24
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Gabriel MC, Howard N, Osborne TZ. Fish mercury and surface water sulfate relationships in the Everglades Protection Area. ENVIRONMENTAL MANAGEMENT 2014; 53:583-93. [PMID: 24385066 PMCID: PMC3931973 DOI: 10.1007/s00267-013-0224-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 12/18/2013] [Indexed: 05/04/2023]
Abstract
Few published studies present data on relationships between fish mercury and surface or pore water sulfate concentrations, particularly on an ecosystem-wide basis. Resource managers can use these relationships to identify the sulfate conditions that contain fish with health-concerning total mercury (THg) levels and to evaluate the role of sulfate in methyl-mercury (MeHg) production. In this study, we derived relationships between THg in three fish trophic levels (mosquitofish, sunfish, and age-1 largemouth bass) and surface water sulfate from 1998 to 2009 for multiple stations across the Everglades Protection Area (EPA). Results show the relationship between sulfate and fish THg in each fish type is nonlinear and largely skewed, similar to the relationship between MeHg production and sulfate concentration in peatland sediment pore water identified by other researchers. Peak fish THg levels occurred in ~1 to 12 mg/L sulfate conditions. There was significant variability in the fish THg data, and there were several instances of high-fish THg levels in high-sulfate conditions (>30 mg/L). Health-concerning fish THg levels were present in all surface water sulfate conditions; however, most of these levels occurred in 1-20 mg/L sulfate. The data in this study, including recent studies, show consistent and identifiable areas of high- and low-fish THg across the spectrum of surface water sulfate concentration, therefore, applying an ecosystem-wide sulfur strategy may be an effective management approach as it would significantly reduce MeHg risk in the EPA.
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Affiliation(s)
- Mark C Gabriel
- USEPA/Office of Research and Development (ORD)/National Exposure Research Laboratory (NERL)/Ecosystem Research Division (ERD), 960 College Station Rd., Athens, GA, 30605, USA,
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25
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Correia RRS, Martins de Oliveira DC, Guimarães JRD. Mercury methylation in mesocosms with and without the aquatic macrophyte Eichhornia crassipes (mart.) Solms. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2013; 96:124-130. [PMID: 23829936 DOI: 10.1016/j.ecoenv.2013.06.002] [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: 02/26/2013] [Revised: 05/29/2013] [Accepted: 06/03/2013] [Indexed: 06/02/2023]
Abstract
Mercury is a toxic pollutant and spreads to several compartments in the environment. Previous in-vitro studies showed that roots of aquatic macrophytes are sites of methylmercury formation, performed mainly by sulfate-reducing bacteria (SRB). The objective of this study was to observe MMHg formation and distribution among filtered water (0.2µm), suspended and settled particles and macrophyte roots during seventeen days, in (203)Hg- spiked mesocosms with and without live Eichhornia crassipes whole plants and a SRB inhibitor. Root samples were also incubated in-vitro for comparison of MM(203)Hg formation under in-vitro and in-vivo conditions. To evaluate the effect of SRB inhibition by sodium molybdate on total heterotrophic activity, the latter was measured by (3)H-leucine uptake. Inhibition of Hg methylation by sodium molybdate decreased with time in mesocosms. MMHg averaged 10, 12.4 and 0.23 percent of total (203)Hg present in filtered water, suspended particles and roots respectively. In vitro MMHg formation in roots averaged 5.54 percent of total added (203)Hg, with a clearer SRB inhibition effect than in mesocosms. Though significant, MMHg formation in roots from in-vivo mesocosms was one order of magnitude lower than previously found in in-vitro incubations of roots alone.
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Affiliation(s)
- Raquel Rose Silva Correia
- Laboratório de Traçadores Wolfgang C. Pfeiffer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G/CCS/Ilha do Fundão, Rio de Janeiro (RJ), CEP 21941-902, Brazil.
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26
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Hsu-Kim H, Kucharzyk KH, Zhang T, Deshusses MA. Mechanisms regulating mercury bioavailability for methylating microorganisms in the aquatic environment: a critical review. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:2441-56. [PMID: 23384298 DOI: 10.1021/es304370g] [Citation(s) in RCA: 408] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Mercury is a potent neurotoxin for humans, particularly if the metal is in the form of methylmercury. Mercury is widely distributed in aquatic ecosystems as a result of anthropogenic activities and natural earth processes. A first step toward bioaccumulation of methylmercury in aquatic food webs is the methylation of inorganic forms of the metal, a process that is primarily mediated by anaerobic bacteria. In this Review, we evaluate the current state of knowledge regarding the mechanisms regulating microbial mercury methylation, including the speciation of mercury in environments where methylation occurs and the processes that control mercury bioavailability to these organisms. Methylmercury production rates are generally related to the presence and productivity of methylating bacteria and also the uptake of inorganic mercury to these microorganisms. Our understanding of the mechanisms behind methylation is limited due to fundamental questions related to the geochemical forms of mercury that persist in anoxic settings, the mode of uptake by methylating bacteria, and the biochemical pathway by which these microorganisms produce and degrade methylmercury. In anoxic sediments and water, the geochemical forms of mercury (and subsequent bioavailability) are largely governed by reactions between Hg(II), inorganic sulfides, and natural organic matter. These interactions result in a mixture of dissolved, nanoparticulate, and larger crystalline particles that cannot be adequately represented by conventional chemical equilibrium models for Hg bioavailability. We discuss recent advances in nanogeochemistry and environmental microbiology that can provide new tools and unique perspectives to help us solve the question of how microorganisms methylate mercury. An understanding of the factors that cause the production and degradation of methylmercury in the environment is ultimately needed to inform policy makers and develop long-term strategies for controlling mercury contamination.
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Affiliation(s)
- Heileen Hsu-Kim
- Department of Civil and Environmental Engineering, Duke University , 121 Hudson Hall, Box 90287, Durham, North Carolina 27708, USA.
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