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Baldwin AK, Willacker JJ, Johnson BL, Janssen SE, Eagles-Smith CA. Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:14396-14409. [PMID: 39078944 PMCID: PMC11325654 DOI: 10.1021/acs.est.4c00789] [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: 08/17/2024]
Abstract
The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference headwater streams across the northwestern U.S. to evaluate the effects of wildfire occurrence and severity on total Hg (THg) and methylmercury (MeHg) transport and bioaccumulation. Suspended particulate THg and MeHg concentrations were 89 and 178% greater in burned watersheds compared to unburned watersheds and increased with burn severity, likely associated with increased soil erosion. Concentrations of filter-passing THg were similar in burned and unburned watersheds, but filter-passing MeHg was 51% greater in burned watersheds, and suspended particles in burned watersheds were enriched in MeHg but not THg, suggesting higher MeHg production in burned watersheds. Among invertebrates, MeHg in grazers, filter-feeders, and collectors was 33, 48, and 251% greater in burned watersheds, respectively, but did not differ in shredders or predators. Thus, increasing wildfire frequency and severity may yield increased MeHg production, mobilization, and bioaccumulation in headwaters and increased transport of particulate THg and MeHg to downstream environments.
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Affiliation(s)
- Austin K Baldwin
- US Geological Survey, Idaho Water Science Center, Boise, Idaho 83702, United States
| | - James J Willacker
- US Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon 97331, United States
| | - Branden L Johnson
- US Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon 97331, United States
| | - Sarah E Janssen
- US Geological Survey, Upper Midwest Water Science Center, Madison, Wisconsin 53726, United States
| | - Collin A Eagles-Smith
- US Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon 97331, United States
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2
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Graca B, Rychter A, Bełdowska M, Wojdasiewicz A. Seasonality of mercury and its fractions in microplastics biofilms -comparison to natural biofilms, suspended particulate matter and bottom sediment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 948:174814. [PMID: 39032739 DOI: 10.1016/j.scitotenv.2024.174814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 07/08/2024] [Accepted: 07/13/2024] [Indexed: 07/23/2024]
Abstract
Biofilms can enhance the sorption of heavy metals onto microplastic (MP) surfaces. However, most research in this field relies on laboratory experiments and neglects metal fractions and seasonal variations. Further studies of the metal/biofilm interaction in the aquatic environment are essential for assessing the ecological threat that MPs pose. The present study used in situ experiments in an environment conducive to biofouling (Vistula Lagoon, Baltic Sea). The objective was to investigate the sorption of mercury and its fractions (thermodesorption technique) in MP (polypropylene-PP, polystyrene-PS, polylactide-PLA) biofilms and natural matrices across three seasons. After one month of incubation, the Hg concentrations in MP and natural substratum (gravel grains-G) biofilms were similar (MP: 145 ± 45 ng/g d.w.; G: 132 ± 23 ng/g d.w.) and approximately twofold those of suspended particulate matter (SPM) (63 ± 27 ng/g d.w.). Hg concentrations in biofilms and sediments were similar, but labile fractions dominated in biofilms and stable fractions in sediments. Seasonal Hg concentrations in MP biofilms decreased over summer>winter>spring, with significant variation for mineral and loosely bound Hg fractions. Multiple regression analysis revealed that hydrochemical conditions and sediment resuspension played a crucial role in the observed variability. The influence of polymer type and morphology (pellets, fibres, aged MP) on Hg sorption in biofilms was visible only in high summer temperatures. In this season, PP fibres and aged PP pellets encouraged biofilm growth and the accumulation of labile Hg fractions. Additionally, high concentrations of mineral (stable and semi-labile) Hg fractions were found in expanded PS biofilms. These findings suggest that organisms that ingest MPs or feed on the biofilms are exposed to the adverse effects of Hg and the presence of MPs in aquatic ecosystems may facilitate the transfer of mercury within the food chain.
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Affiliation(s)
- Bożena Graca
- University of Gdansk, Faculty of Oceanography and Geography, Al. Marszałka Piłsudskiego 46, 81-378 Gdynia, Poland.
| | - Agata Rychter
- University of Applied Sciences in Elbląg, Ul. Wojska Polskiego 1, 82-300 Elbląg, Poland
| | - Magdalena Bełdowska
- University of Gdansk, Faculty of Oceanography and Geography, Al. Marszałka Piłsudskiego 46, 81-378 Gdynia, Poland
| | - Adriana Wojdasiewicz
- University of Gdansk, Faculty of Oceanography and Geography, Al. Marszałka Piłsudskiego 46, 81-378 Gdynia, Poland
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3
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Zhang S, Xia M, Pan Z, Wang J, Yin Y, Lv J, Hu L, Shi J, Jiang T, Wang D. Soil organic matter degradation and methylmercury dynamics in Hg-contaminated soils: Relationships and driving factors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 356:120432. [PMID: 38479282 DOI: 10.1016/j.jenvman.2024.120432] [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: 11/06/2023] [Revised: 02/01/2024] [Accepted: 02/17/2024] [Indexed: 04/07/2024]
Abstract
Biodegradation of soil organic matter (SOM), which involves greenhouse gas (GHG) emissions, plays an essential role in the global carbon cycle. Over the past few decades, this has become an important research focus, particularly in natural ecosystems. SOM biodegradation significantly affects contaminants in the environment, such as mercury (Hg) methylation, producing highly toxic methylmercury (MeHg). However, the potential link between GHG production from SOM turnover in contaminated soils and biogeochemical processes involving contaminants remains unclear. In this study, we investigated the dynamics of GHG, MeHg production, and the relationship between biogeochemical processes in soils from two typical Hg mining sites. The two contaminated soils have different pathways, explaining the significant variations in GHG and MeHg production. The divergence of the microbial communities in these two biogeochemical processes is essential. In addition to the microbial role, abiotic factors such as Hg species can significantly affect MeHg production. On the other hand, we found an inverse relationship between CH4 and MeHg, suggesting that carbon emission reduction policies and management could inadvertently increase the MeHg levels. This highlights the need for an eclectic approach to organic carbon sequestration and contaminant containment. These findings suggest that it is difficult to establish a general pattern to describe and explain the SOM degradation and MeHg production in contaminated soils within the specific scenarios. However, this study provides a case study and helpful insights for further understanding the links between environmental risks and carbon turnover in Hg mining areas.
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Affiliation(s)
- Siqi Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Meng Xia
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Zhaoyang Pan
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China; 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
| | - Jianxu Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Yongguang Yin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jitao Lv
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Tao Jiang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China.
| | - Dingyong Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
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4
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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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5
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Baldwin AK, Janssen SE, Tate MT, Poulin BA, Yoder AM, Naymik J, Larsen C, Hoovestol C, Krabbenhoft DP. Mercury sources and budget for the Snake River above a hydroelectric reservoir complex. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167961. [PMID: 37865255 DOI: 10.1016/j.scitotenv.2023.167961] [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: 08/16/2023] [Revised: 10/13/2023] [Accepted: 10/18/2023] [Indexed: 10/23/2023]
Abstract
Understanding sources of mercury (Hg) and methylmercury (MeHg) to a water body is critical for management but is often complicated by poorly characterized Hg inputs and in situ processes, such as inorganic Hg methylation. In this study, we determined inorganic Hg and MeHg concentrations and loads (filter-passing and particulate fractions) for a semi-arid 164-kilometer stretch of the Snake River above the Hells Canyon Complex, a Hg-impaired hydroelectric reservoir complex on the Idaho-Oregon border, and used water quality measurements and Hg stable isotope ratios to create a comprehensive Hg source budget for the river. Results show that whereas most of the streamflow to the study reach comes from the main branch of the Snake River (i.e., the upstream watershed), major tributaries within the study reach contribute a greater proportion of inorganic Hg and MeHg loads. Mercury stable-isotope analyses highlight that Hg within the tributaries is predominantly associated with geologic deposits and snowmelt sources, the latter reflecting wet deposition. Surprisingly, irrigation return drains contribute 40-50 % of particulate inorganic Hg loads despite being ≤4.3 % of the overall water budget. Together, tributaries and irrigation return drains account for 97-100 % of the inorganic Hg and streamflow to the study reach, but ~65 % of the MeHg, indicating in-stream and riparian methylation may be an important and previously unrecognized source of MeHg. Streamflow, total suspended solids, dissolved organic carbon, and agricultural land cover were found to be important controls on the mobilization and transport of different Hg species and fractions. This study represents the first fluvial budget for Hg in the Snake River that accounts for particulate and filter-passing Hg species from both major tributaries and irrigation return drains, and expands our understanding of Hg sources and methylation processes within semi-arid environments. This information is critical to inform management decisions related to elevated Hg burdens in biota.
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Affiliation(s)
- Austin K Baldwin
- U.S. Geological Survey, Idaho Water Science Center, United States of America.
| | - Sarah E Janssen
- U.S. Geological Survey, Upper Midwest Water Science Center, United States of America
| | - Michael T Tate
- U.S. Geological Survey, Upper Midwest Water Science Center, United States of America
| | - Brett A Poulin
- Department of Environmental Toxicology, University of California at Davis, United States of America
| | - Alysa M Yoder
- U.S. Geological Survey, Idaho Water Science Center, United States of America
| | | | | | | | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, United States of America
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6
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Leclerc M, Ponton DE, Bilodeau F, Planas D, Amyot M. Enhanced Bioaccumulation and Transfer of Monomethylmercury through Periphytic Biofilms in Benthic Food Webs of a River Affected by Run-of-River Dams. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:20792-20801. [PMID: 38016692 PMCID: PMC10720379 DOI: 10.1021/acs.est.3c05585] [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: 07/14/2023] [Revised: 11/03/2023] [Accepted: 11/03/2023] [Indexed: 11/30/2023]
Abstract
Run-of-river (ROR) power plants impound limited terrestrial areas compared to traditional hydropower plants with large reservoirs and are assumed to have reduced impacts on mercury cycling. We conducted a study on periphyton and benthic communities from different habitats of the St. Maurice River (Québec, Canada) affected by two ROR power plants and their effect on the bioaccumulation and biomagnification of monomethylmercury (MMHg). Proportion of total mercury as MMHg reached maximum values about 2.9 times higher in flooded sites compared to unflooded sites. Impoundment by ROR would therefore provide favorable environments for the growth of periphyton, which can produce and accumulate MMHg. Periphyton MMHg concentrations significantly explained concentrations in some benthic macroinvertebrates, reflecting a local transfer. Through the analysis of δ13C and δ15N signatures, we found that flooding, creating scattered lenthic habitats, led to modifications in trophic structures by the introduction of new organic matter sources. The computed trophic magnification slopes did not show significant differences in the transfer efficiency of MMHg between sectors, while intercepts of flooded sectors were higher. Increases in MMHg concentrations in flooded areas are likely due to the impoundment, combined with watershed disturbances, and the creation of small habitats favorable to periphyton should be included in future predictive models.
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Affiliation(s)
- Maxime Leclerc
- GRIL,
GEOTOP, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, Québec H2V 0B3, Canada
| | - Dominic E. Ponton
- GRIL,
GEOTOP, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, Québec H2V 0B3, Canada
| | - François Bilodeau
- Hydro-Québec,
Direction Environnement, 800 De Maisonneuve Est Blvd., Montréal, Québec H2Z 1A4, Canada
| | - Dolors Planas
- GRIL,
GEOTOP, Département de Sciences Biologiques, Université du Québec à Montréal, 141 Président-Kennedy Ave., Montréal, Québec H2X 1Y4, Canada
| | - Marc Amyot
- GRIL,
GEOTOP, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, Québec H2V 0B3, Canada
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7
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Burguera S, Sahu AK, Frontera A, Biswal HS, Bauza A. Spodium Bonds Involving Methylmercury and Ethylmercury in Proteins: Insights from X-ray Analysis and Computations. Inorg Chem 2023; 62:18524-18532. [PMID: 37902775 PMCID: PMC10647129 DOI: 10.1021/acs.inorgchem.3c02716] [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: 08/05/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 10/31/2023]
Abstract
In this study, the stability, directionality, and physical nature of Spodium bonds (SpBs, an attractive noncovalent force involving elements from group 12 and Lewis bases) between methylmercury (MeHg) and ethylmercury (EtHg) and amino acids (AAs) have been analyzed from both a structural (X-ray analysis) and theoretical (RI-MP2/def2-TZVP level of theory) point of view. More in detail, an inspection of the Protein Data Bank (PDB) reported evidence of noncovalent contacts between MeHg and EtHg molecules and electron-rich atoms (e.g., O atoms belonging to the protein backbone and S atoms from MET residues or the π-systems of aromatic AAs such as TYR or TRP). These results were rationalized through a computational study using MeHg coordinated to a thiolate group as a theoretical model and several neutral and charged electron-rich molecules (e.g., benzene, formamide, or chloride). The physical nature of the interaction was analyzed from electrostatics and orbital perspectives by performing molecular electrostatic potential (MEP) and natural bonding orbital (NBO) analyses. Lastly, the noncovalent interactions plot (NCIplot) technique was used to provide a qualitative view of the strength of the Hg SpBs and compare them to other ancillary interactions present in these systems as well as to shed light on the extension of the interaction in real space. We believe that the results derived from our study will be useful to those scientists devoted to protein engineering and bioinorganic chemistry as well as to expanding the current knowledge of SpBs among the chemical biology community.
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Affiliation(s)
- Sergi Burguera
- Department
of Chemistry, Universitat de les Illes Balears, Ctra. de Valldemossa km 7.5, 07122 Palma, Baleares, Spain
| | - Akshay Kumar Sahu
- School
of Chemical Sciences, National Institute
of Science Education and Research (NISER), Bhubaneswar 752050, India
- Training
School Complex, Homi Bhabha National Institute, Mumbai 400094, India
| | - Antonio Frontera
- Department
of Chemistry, Universitat de les Illes Balears, Ctra. de Valldemossa km 7.5, 07122 Palma, Baleares, Spain
| | - Himansu S. Biswal
- School
of Chemical Sciences, National Institute
of Science Education and Research (NISER), Bhubaneswar 752050, India
- Training
School Complex, Homi Bhabha National Institute, Mumbai 400094, India
| | - Antonio Bauza
- Department
of Chemistry, Universitat de les Illes Balears, Ctra. de Valldemossa km 7.5, 07122 Palma, Baleares, Spain
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8
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Xiang Y, Guo Y, Liu G, Liu Y, Song M, Shi J, Hu L, Yin Y, Cai Y, Jiang G. Direct Uptake and Intracellular Dissolution of HgS Nanoparticles: Evidence from a Bacterial Biosensor Approach. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:14994-15003. [PMID: 37755700 DOI: 10.1021/acs.est.3c02664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
Mercury sulfide nanoparticles (HgSNPs), which occur widely in oxic and anoxic environments, can be microbially converted to highly toxic methylmercury or volatile elemental mercury, but it remains challenging to assess their bioavailability. In this study, an Escherichia coli-based whole-cell fluorescent biosensor was developed to explore the bioavailability and microbial activation process of HgSNPs. Results show that HgSNPs (3.17 ± 0.96 nm) trigger a sharp increase in fluorescence intensity of the biosensor, with signal responses almost equal to that of ionic Hg (Hg(II)) within 10 h, indicating high bioavailability of HgSNP. The intracellular total Hg (THg) of cells exposed to HgSNPs (200 μg L-1) was 3.52-8.59-folds higher than that of cells exposed to Hg(II) (200 μg L-1), suggesting that intracellular HgSNPs were only partially dissolved. Speciation analysis using size-exclusion chromatography (SEC)-inductively coupled plasma mass spectrometry (ICP-MS) revealed that the bacterial filtrate was not responsible for HgSNP dissolution, suggesting that HgSNPs entered cells in nanoparticle form. Combined with fluorescence intensity and intracellular THg analysis, the intracellular HgSNP dissolution ratio was estimated at 22-29%. Overall, our findings highlight the rapid internalization and high intracellular dissolution ratio of HgSNPs by E. coli, and intracellular THg combined with biosensors could provide innovative tools to explore the microbial uptake and dissolution of HgSNPs.
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Affiliation(s)
- Yuping Xiang
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yingying Guo
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Guangliang Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Yanwei Liu
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Maoyong Song
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Institute of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yong Cai
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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9
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Schneider L, Fisher JA, Diéguez MC, Fostier AH, Guimaraes JRD, Leaner JJ, Mason R. A synthesis of mercury research in the Southern Hemisphere, part 1: Natural processes. AMBIO 2023; 52:897-917. [PMID: 36943620 PMCID: PMC10073387 DOI: 10.1007/s13280-023-01832-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/30/2022] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
Recent studies demonstrate a short 3-6-month atmospheric lifetime for mercury (Hg). This implies Hg emissions are predominantly deposited within the same hemisphere in which they are emitted, thus placing increasing importance on considering Hg sources, sinks and impacts from a hemispheric perspective. In the absence of comprehensive Hg data from the Southern Hemisphere (SH), estimates and inventories for the SH have been drawn from data collected in the NH, with the assumption that the NH data are broadly applicable. In this paper, we centre the uniqueness of the SH in the context of natural biogeochemical Hg cycling, with focus on the midlatitudes and tropics. Due to its uniqueness, Antarctica warrants an exclusive review of its contribution to the biogeochemical cycling of Hg and is therefore excluded from this review. We identify and describe five key natural differences between the hemispheres that affect the biogeochemical cycling of Hg: biome heterogeneity, vegetation type, ocean area, methylation hotspot zones and occurence of volcanic activities. We review the current state of knowledge of SH Hg cycling within the context of each difference, as well as the key gaps that impede our understanding of natural Hg cycling in the SH. The differences demonstrate the limitations in using NH data to infer Hg processes and emissions in the SH.
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Affiliation(s)
- Larissa Schneider
- School of Culture, History and Language. Australian National University, Coombs Bld 9 Fellows Rd, Acton. Canberra, ACT 2601 Australia
| | - Jenny A. Fisher
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 Australia
| | - María C. Diéguez
- Instituto de Investigaciones en Biodiversidad y Medioambiente (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional del Comahue), 1250 San Carlos de Bariloche (8400), Quintral Argentina
| | - Anne-Hélène Fostier
- Instituto de Química/Unicamp, Rua Josué de Castro, s/n – Cidade Universitária, Campinas, SP 13083-970 Brazil
| | - Jean R. D. Guimaraes
- Lab. de Traçadores, Inst. de Biofísica, Bloco G, CCS (Centro de Ciências da Saúde), Av. Carlos Chagas Filho 373, Rio de Janeiro, Ilha do Fundão CEP 21941-902 Brazil
| | - Joy J. Leaner
- Department of Environmental Affairs and Development Planning, Western Cape Government, 1 Dorp Street, Western Cape, Cape Town, 8001 South Africa
| | - Robert Mason
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT 06340 USA
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10
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Zhang J, Li C, Tang W, Wu M, Chen M, He H, Lei P, Zhong H. Mercury in wetlands over 60 years: Research progress and emerging trends. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 869:161862. [PMID: 36716881 DOI: 10.1016/j.scitotenv.2023.161862] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/04/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Wetlands are considered the hotspots for mercury (Hg) biogeochemistry, garnering global attention. Therefore, it is important to review the research progress in this field and predict future frontiers. To achieve that, we conducted a literature analysis by collecting 15,813 publications about Hg in wetlands from the Web of Science Core Collection. The focus of wetland Hg research has changed dramatically over time: 1) In the initial stage (i.e., 1959-1990), research mainly focused on investigating the sources and contents of Hg in wetland environments and fish. 2) For the next 20 years (i.e., 1991-2010), Hg transformation (e.g., Hg reduction and methylation) and environmental factors that affect Hg bioaccumulation have attracted extensive attention. 3) In the recent years of 2011-2022, hot topics in Hg study include microbial Hg methylators, Hg bioavailability, methylmercury (MeHg) demethylation, Hg stable isotope, and Hg cycling in paddy fields. Finally, we put forward future research priorities, i.e., 1) clarifying the primary factors controlling MeHg production, 2) uncovering the MeHg demethylation process, 3) elucidating MeHg bioaccumulation process to better predict its risk, and 4) recognizing the role of wetlands in Hg circulation. This research shows a comprehensive knowledge map for wetland Hg research and suggests avenues for future studies.
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Affiliation(s)
- Jin Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Chengjun Li
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
| | - Wenli Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Mengjie Wu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Mingying Chen
- School of Environment, Nanjing Normal University, Nanjing 210023, China
| | - Huan He
- School of Environment, Nanjing Normal University, Nanjing 210023, China
| | - Pei Lei
- School of Environment, Nanjing Normal University, Nanjing 210023, China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario, Canada
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11
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Negrazis L, Kidd KA, Erdozain M, Emilson EJS, Mitchell CPJ, Gray MA. Effects of forest management on mercury bioaccumulation and biomagnification along the river continuum. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 310:119810. [PMID: 35940481 DOI: 10.1016/j.envpol.2022.119810] [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: 02/07/2022] [Revised: 07/15/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
Forest management can alter the mobilization of mercury (Hg) into headwater streams and its conversion to methylmercury (MeHg), the form that bioaccumulates in aquatic biota and biomagnifies through food webs. As headwater streams are important sources of organic materials and nutrients to larger systems, this connectivity may also increase MeHg in downstream biota through direct or indirect effects of forestry on water quality or food web structure. In this study, we collected water, seston, food sources (biofilm, leaves, organic matter), five macroinvertebrate taxa and fish (slimy sculpin; Cottus cognata) at 6 sites representing different stream orders (1-5) within three river basins with different total disturbances from forestry (both harvesting and silviculture). Methylmercury levels were highest in water and some food sources from the basin with moderate disturbance (greater clearcutting but less silviculture). Water, leaves, stoneflies and fish increased in MeHg or total Hg along the river continuum in the least disturbed basin, and there were some dissipative effects of forest management on these spatial patterns. Trophic level (δ15N) was a significant predictor of MeHg (and total Hg in fish) within food webs across all 18 sites, and biomagnification slopes were significantly lower in the basin with moderate total disturbance but not different in the other two basins. The elevated MeHg in lower trophic levels but its reduced trophic transfer in the basin with moderate disturbance was likely due to greater inputs of sediments and of dissolved organic carbon that is more humic, as these factors are known to both increase transport of Hg to streams and its uptake in primary producers but to also decrease MeHg bioaccumulation in consumers. Overall, these results suggest that the type of disturbance from forestry affects MeHg bioaccumulation and trophic transfer in stream food webs and some longitudinal patterns along a river continuum.
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Affiliation(s)
- Lauren Negrazis
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Karen A Kidd
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada; School of Earth, Environment and Society, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada.
| | - Maitane Erdozain
- Canadian Rivers Institute and Biology Department, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada
| | - Erik J S Emilson
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, Ontario P6A 2E5, Canada
| | - Carl P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | - Michelle A Gray
- Canadian Rivers Institute, Faculty of Forestry and Environmental Management, University of New Brunswick, 28 Dineen Drive, Fredericton, New Brunswick E3B 5A3, Canada
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12
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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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13
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Barkay T, Gu B. Demethylation─The Other Side of the Mercury Methylation Coin: A Critical Review. ACS ENVIRONMENTAL AU 2022; 2:77-97. [PMID: 37101582 PMCID: PMC10114901 DOI: 10.1021/acsenvironau.1c00022] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The public and environmental health consequences of mercury (Hg) methylation have drawn much attention and considerable research to Hg methylation processes and their dynamics in diverse environments and under a multitude of conditions. However, the net methylmercury (MeHg) concentration that accumulates in the environment is equally determined by the rate of MeHg degradation, a complex process mediated by a variety of biotic and abiotic mechanisms, about which our knowledge is limited. Here we review the current knowledge on MeHg degradation and its potential pathways and mechanisms. We describe detoxification by resistant microorganisms that employ the Hg resistance (mer) system to reductively break the carbon-mercury (C-Hg) bond producing methane (CH4) and inorganic mercuric Hg(II), which is then reduced by the mercuric reductase to elemental Hg(0). Very recent research has begun to elucidate a mechanism for the long-recognized mer-independent oxidative demethylation, likely involving some strains of anaerobic bacteria as well as aerobic methane-oxidizing bacteria, i.e., methanotrophs. In addition, photochemical and chemical demethylation processes are described, including the roles of dissolved organic matter (DOM) and free radicals as well as dark abiotic demethylation in the natural environment about which little is currently known. We focus on mechanisms and processes of demethylation and highlight the uncertainties and known effects of environmental factors leading to MeHg degradation. Finally, we suggest future research directions to further elucidate the chemical and biochemical mechanisms of biotic and abiotic demethylation and their significance in controlling net MeHg production in natural ecosystems.
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Affiliation(s)
- Tamar Barkay
- Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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14
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Neal-Walthall N, Ndu U, Rivera NA, Elias DA, Hsu-Kim H. Utility of Diffusive Gradient in Thin-Film Passive Samplers for Predicting Mercury Methylation Potential and Bioaccumulation in Freshwater Wetlands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:1743-1752. [PMID: 35044747 PMCID: PMC9630924 DOI: 10.1021/acs.est.1c06796] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mercury is a risk in aquatic ecosystems when the metal is converted to methylmercury (MeHg) and subsequently bioaccumulates in aquatic food webs. This risk can be difficult to manage because of the complexity of biogeochemical processes for mercury and the need for accessible techniques to navigate this complexity. Here, we explored the use of diffusive gradient in thin-film (DGT) passive samplers as a tool to simultaneously quantify the methylation potential of inorganic Hg (IHg) and the bioaccumulation potential of MeHg in freshwater wetlands. Outdoor freshwater wetland mesocosms were amended with four isotopically labeled and geochemically relevant IHg forms that represent a range of methylation potentials (202Hg2+, 201Hg-humic acid, 199Hg-sorbed to FeS, and 200HgS nanoparticles). Six weeks after the spikes, we deployed DGT samplers in the mesocosm water and sediments, evaluated DGT-uptake rates of total Hg, MeHg, and IHg (calculated by difference) for the Hg isotope spikes, and examined correlations with total Hg, MeHg, and IHg concentrations in sediment, water, and micro and macrofauna in the ecosystem. In the sediments, we observed greater relative MeHg concentrations from the initially dissolved IHg isotope spikes and lower MeHg levels from the initially particulate IHg spikes. These trends were consistent with uptake flux of IHg into DGTs deployed in surface sediments. Moreover, we observed correlations between total Hg-DGT uptake flux and MeHg levels in periphyton biofilms, submergent plant stems, snails, and mosquitofish in the ecosystem. These correlations were better for DGTs deployed in the water column compared to DGTs in the sediments, suggesting the importance of vertical distribution of bioavailable MeHg in relation to food sources for macrofauna. Overall, these results demonstrate that DGT passive samplers are a relatively simple and efficient tool for predicting IHg methylation and MeHg bioaccumulation potentials without the need to explicitly delineate IHg and MeHg speciation and partitioning in complex ecosystems.
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Affiliation(s)
- Natalia Neal-Walthall
- Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, North Carolina 27708, United States
| | - Udonna Ndu
- Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, North Carolina 27708, United States
- Harte Research Institute for Gulf of Mexico Studies, Texas A&M Corpus Christi, Corpus Christi, TX, 78412, United States
| | - Nelson A. Rivera
- Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, North Carolina 27708, United States
| | - Dwayne A. Elias
- Elias Consulting, LLC, Knoxville, Tennessee 37934, United States
| | - Heileen Hsu-Kim
- Department of Civil and Environmental Engineering, Duke University, Box 90287, Durham, North Carolina 27708, United States
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15
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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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16
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Xiang Y, Liu G, Yin Y, Cai Y. Periphyton as an important source of methylmercury in Everglades water and food web. JOURNAL OF HAZARDOUS MATERIALS 2021; 410:124551. [PMID: 33223320 DOI: 10.1016/j.jhazmat.2020.124551] [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: 06/22/2020] [Revised: 09/23/2020] [Accepted: 11/10/2020] [Indexed: 06/11/2023]
Abstract
Periphyton is ubiquitous in Florida Everglades and has a profound effect on mercury (Hg) cycling. Enhanced methylmercury (MeHg) production in periphyton has been well documented, but the re-distribution of MeHg from periphyton remains unknown. In this study, periphyton, sediments, surface water, periphyton overlying water, and periphyton porewater were collected from Everglades for analyzing the distribution of MeHg and total Hg (THg). Results showed that there were no significant differences in THg and MeHg in different types of periphyton, but they all displayed higher MeHg levels than sediments. MeHg distribution coefficients (logkd) in periphyton were lower than in sediments, suggesting that periphyton MeHg could be more labile entering aquatic cycling and bioaccumulation. In water, the more the distance of water samples taken from periphyton, the lower the MeHg and dissolved organic carbon concentrations were detected. In extracellular polymeric substances of periphyton, MeHg in colloidal fractions was significantly higher than that in capsular fractions. It was estimated that approximately 10% (or 1.35 kg) of periphyton MeHg were passed on to mosquitofish entering the food web during wet season, contributing 73% of total Hg stocked in mosquitofish. These results revealed the importance of periphyton on water MeHg distribution and MeHg bioaccumulation in Everglades.
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Affiliation(s)
- Yuping Xiang
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Guangliang Liu
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Cai
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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17
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Leclerc M, Harrison MC, Storck V, Planas D, Amyot M, Walsh DA. Microbial Diversity and Mercury Methylation Activity in Periphytic Biofilms at a Run-of-River Hydroelectric Dam and Constructed Wetlands. mSphere 2021; 6:e00021-21. [PMID: 33731467 PMCID: PMC8546676 DOI: 10.1128/msphere.00021-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/24/2021] [Indexed: 01/04/2023] Open
Abstract
Periphytic biofilms have the potential to greatly influence the microbial production of the neurotoxicant monomethylmercury in freshwaters although few studies have simultaneously assessed periphyton mercury methylation and demethylation rates and the microbial communities associated with these transformations. We performed a field study on periphyton from a river affected by run-of-river power plants and artificial wetlands in a boreal landscape (Québec, Canada). In situ incubations were performed on three sites using environmental concentrations of isotopically enriched monomethylmercury (MM198Hg) and inorganic mercury (200Hg) for demethylation and methylation rate measurements. Periphytic microbial communities were investigated through 16S rRNA gene analyses and metagenomic screenings for the hgcA gene, involved in mercury methylation. Positive mercury methylation rates ([5.9 ± 3.4] × 10-3 day-1) were observed only in the wetlands, and demethylation rates averaged 1.78 ± 0.21 day-1 for the three studied sites. The 16S rRNA gene analyses revealed Proteobacteria as the most abundant phylum across all sites (36.3% ± 1.4%), from which families associated with mercury methylation were mostly found in the wetland site. Metagenome screening for HgcA identified 24 different hgcA sequences in the constructed wetland site only, associated with 8 known families, where the iron-reducing Geobacteraceae were the most abundant. This work brings new information on mercury methylation in periphyton from habitats of impacted rivers, associating it mostly with putative iron-reducing bacteria.IMPORTANCE Monomethylmercury (MMHg) is a biomagnifiable neurotoxin of global concern with risks to human health mostly associated with fish consumption. Hydroelectric reservoirs are known to be sources of MMHg many years after their impoundment. Little is known, however, on run-of-river dams flooding smaller terrestrial areas, although their numbers are expected to increase considerably worldwide in decades to come. Production of MMHg is associated mostly with anaerobic processes, but Hg methylation has been shown to occur in periphytic biofilms located in oxic zones of the water column. Therefore, in this study, we investigated in situ production of MMHg by periphytic communities in habitats impacted by the construction of a run-of-river dam by combining transformation rate measurements with genomic approaches targeting hgcAB genes, responsible for mercury methylation. These results provide extended knowledge on mercury methylators in river ecosystems impacted by run-of-river dams in temperate habitats.
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Affiliation(s)
- Maxime Leclerc
- GRIL, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
- GRIL, Département de Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | | | - Veronika Storck
- GRIL, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
- Department of Biology, Concordia University, Montréal, Québec, Canada
| | - Dolors Planas
- GRIL, Département de Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Marc Amyot
- GRIL, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
| | - David A Walsh
- Department of Biology, Concordia University, Montréal, Québec, Canada
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18
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Cao D, Chen W, Xiang Y, Mi Q, Liu H, Feng P, Shen H, Zhang C, Wang Y, Wang D. The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 207:111538. [PMID: 33254400 DOI: 10.1016/j.ecoenv.2020.111538] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 06/12/2023]
Abstract
Limited information is available about the bio-methylation of inorganic mercury (iHg) under aerobic conditions. In this study, two γ-proteobacteria strains (P. fluorescens TGR-B2 and P. putida TGR-B4) were obtained from the soil of The Three Gorges Reservoir (TGR), demonstrating effective aerobic transformation capacities of iHg into methylmercury (MeHg). Based on periodical changes in soil oxygen content of the TGR, a culture system was established, in which 300 ng Hg (II) L-1 and O2 were set at 7%, 14%, and 21%, respectively. Results indicated that the two strains differed significantly in bacterial growth rate and MeHg production. The kinetic model of MeHg showed typical characteristics of a "two-staged" process: The first stage was dominated by bio-methylation, which was shown by increasing of net MeHg content. Moreover, the second stage was dominated by bio-demethylation, which decreased net MeHg content. Thus, we hypothesized that the mechanism of aerobic bacterial iHg bio-methylation: (1) should inefficiency compared to anaerobic bacteria i.e.SRB, which were regulated by hgcA/B gene clusters, (2) might be regarded as a passive stress response and depended on the bacterial iHg intoxication threshold and MeHg tolerance threshold.
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Affiliation(s)
- Dan Cao
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Weihong Chen
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Qianfen Mi
- Biological Science Research Center of Southwest University, Chongqing 400715, China
| | - Hang Liu
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - PengYu Feng
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Hong Shen
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China.
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China.
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19
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Branfireun BA, Cosio C, Poulain AJ, Riise G, Bravo AG. Mercury cycling in freshwater systems - An updated conceptual model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 745:140906. [PMID: 32758756 DOI: 10.1016/j.scitotenv.2020.140906] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
The widely accepted conceptual model of mercury (Hg) cycling in freshwater lakes (atmospheric deposition and runoff of inorganic Hg, methylation in bottom sediments and subsequent bioaccumulation and biomagnification in biota) is practically accepted as common knowledge. There is mounting evidence that the dominant processes that regulate inputs, transformations, and bioavailability of Hg in many lakes may be missing from this picture, and the fixation on the temperate stratified lake archetype is impeding our exploration of understudied, but potentially important sources of methylmercury to freshwater lakes. In this review, the importance of understudied biogeochemical processes and sites of methylmercury production are highlighted, including the complexity of redox transformations of Hg within the lake system itself, the complex assemblage of microbes found in biofilms and periphyton (two vastly understudied important sources of methylmercury in many freshwater ecosystems), and the critical role of autochthonous and allochthonous dissolved organic matter which mediates the net supply of methylmercury from the cellular to catchment scale. A conceptual model of lake Hg in contrasting lakes and catchments is presented, highlighting the importance of the autochthonous and allochthonous supply of dissolved organic matter, bioavailable inorganic mercury and methylmercury and providing a framework for future convergent research at the lab and field scales to establish more mechanistic process-based relationships within and among critical compartments that regulate methylmercury concentrations in freshwater ecosystems.
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Affiliation(s)
- Brian A Branfireun
- Department of Biology and Centre for Environment & Sustainability, The University of Western Ontario, London, Canada.
| | - Claudia Cosio
- Université de Reims Champagne-Ardenne, UMR I-02 SEBIO, Reims, France
| | | | - Gunnhild Riise
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Andrea G Bravo
- Spanish National Research Council | CSIC, Institut de Ciències del Mar, Barcelona, Spain.
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20
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Influence of Macrophyte and Gut Microbiota on Mercury Contamination in Fish: A Microcosms Study. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10041500] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The freshwater lakes of southwestern France are subject to the development of invasive macrophytes which are associated with mercury (Hg) contamination of the food web. The aim of this study was to determine the bioavailability of methylmercury (MeHg) produced by plant roots in aquatic ecosystems. A microcosm experiment was performed using isotopically enriched inorganic Hg at environmental concentrations (1 µg 199IHg·L−1). For all conditions, total Hg in fish as well as Hg species associated with different compartments (water, sediments, plant roots, fish) were analyzed by gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). In addition, sediment, plants, and fish gut microbiota were studied by MiSEQ sequencing. Some strains were isolated and tested for their ability to methylate Hg. The results revealed 199MeHg production in plant roots and the presence of this form in fish (tissues and gut), highlighting a MeHg trophic transfer. Moreover, methylator bacteria were identified from the gut contents of the fish when they were in the presence of plants. Some of them were related to bacteria found in the plant roots. On the basis of these results, the transfer of MeHg and bacteria from plants to fish is highlighted; in addition, Hg methylation is strongly suspected in the fish gut, potentially increasing the Hg bioaccumulation.
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21
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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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Roxanna Razavi N, Cushman SF, Halfman JD, Massey T, Beutner R, Cleckner LB. Mercury bioaccumulation in stream food webs of the Finger Lakes in central New York State, USA. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 172:265-272. [PMID: 30711861 DOI: 10.1016/j.ecoenv.2019.01.060] [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: 07/05/2018] [Revised: 01/07/2019] [Accepted: 01/15/2019] [Indexed: 06/09/2023]
Abstract
Studies of mercury (Hg) bioaccumulation in streams draining both forested and agricultural watersheds are not common. Sixteen streams were sampled in the Finger Lakes region in central New York State with a mean agricultural land cover of 48%. Stream fish (Blacknose Dace, Rhinichthys atratulus, an invertivore; and Creek Chub, Semotilus atromaculatus, an omnivore) were collected and analyzed for total Hg (THg), and macroinvertebrates and periphyton were collected and analyzed for methylmercury (MeHg) determination. The effect of water chemistry, land cover, and macroinvertebrate MeHg was assessed as predictors of fish Hg concentrations. Blacknose Dace had significantly higher THg concentrations compared to Creek Chub (229 ng/g vs. 195 ng/g dry weight, respectively), and predatory and omnivorous macroinvertebrates (i.e., Perlidae and Cambaridae) were found to have significantly higher MeHg concentrations compared to other functional feeding groups. Mixed effects models identified macroinvertebrate MeHg concentrations as predictors of stream fish THg concentrations. Partition modeling found fish total length and total suspended solids predicted Blacknose Dace with 'High' vs 'Low' Hg (≥ or < 90 ng/g wet weight, respectively). Overall, stream fish THg concentrations observed were not of concern, unlike other regions in New York State such as the Adirondack Mountains, but a significant proportion of Blacknose Dace (22 - 73%) and Creek Chub (5 - 69%) would be considered a risk to a range of sensitive consumers.
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Affiliation(s)
- N Roxanna Razavi
- Finger Lakes Institute, Hobart and William Smith Colleges, Geneva, NY 14556, USA.
| | - Susan F Cushman
- Finger Lakes Institute, Hobart and William Smith Colleges, Geneva, NY 14556, USA; Department of Biology, Hobart and William Smith Colleges, Geneva, NY 14556, USA; Environmental Studies Program, Hobart and William Smith Colleges, Geneva, NY 14556, USA
| | - John D Halfman
- Finger Lakes Institute, Hobart and William Smith Colleges, Geneva, NY 14556, USA; Environmental Studies Program, Hobart and William Smith Colleges, Geneva, NY 14556, USA; Department of Geoscience, Hobart and William Smith Colleges, Geneva, NY 14556, USA
| | - Trevor Massey
- Finger Lakes Institute, Hobart and William Smith Colleges, Geneva, NY 14556, USA
| | - Robert Beutner
- IT Services, Hobart and William Smith Colleges, Geneva, NY 14556, USA
| | - Lisa B Cleckner
- Finger Lakes Institute, Hobart and William Smith Colleges, Geneva, NY 14556, USA; Environmental Studies Program, Hobart and William Smith Colleges, Geneva, NY 14556, USA
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23
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Liu J, Tang J, Wan J, Wu C, Graham B, Kerr PG, Wu Y. Functional sustainability of periphytic biofilms in organic matter and Cu 2+ removal during prolonged exposure to TiO 2 nanoparticles. JOURNAL OF HAZARDOUS MATERIALS 2019; 370:4-12. [PMID: 28886877 DOI: 10.1016/j.jhazmat.2017.08.068] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/04/2017] [Accepted: 08/28/2017] [Indexed: 06/07/2023]
Abstract
Responses of microbial communities to nanotoxicity in aquatic ecosystems are largely unknown, particularly with respect to relationship between community dynamics and functions. Here, periphytic biofilms were selected as a model of species-rich microbial communities to elucidate their responses when exposed to titanium dioxide nanoparticles (TiO2-NPs). Especially, the relationships between the functions (e.g. organic matter and Cu2+ removal) and community dynamics after long-term exposure to TiO2-NPs were assessed systematically. After 5days exposure to TiO2-NPs (5mgL-1), periphytic biofilms showed sustainable functions in pollutant removal and strong plasticity in defensing the toxic disturbance of TiO2-NPs, including photosynthesis and carbon metabolic diversity. The sustainable pollutant removal functions of periphytic biofilms were attributed to their functional redundancy. Specifically, periphytic biofilms altered their composition with cyanobacteria, Sphingobacteriia and Spirochaetes being the newly dominant taxa, and changed the carbon substrate utilization pattern to maintain high photosynthesis and metabolic rates. Moreover, extracellular polymeric substances (EPS) especially proteins were overproduced to bind the NPs and thereby reduce the nanotoxicity. The information obtained in this study may greatly help to understand the interactions between microbial community dynamics and function under NPs exposure conditions and functional redundancy is an important mechanism of periphytic biofilms to maintain sustainable functions.
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Affiliation(s)
- Junzhuo Liu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences,71 East Beijing Road, Nanjing 210008, China
| | - Jun Tang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences,71 East Beijing Road, Nanjing 210008, China
| | - Juanjuan Wan
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences,71 East Beijing Road, Nanjing 210008, China; School of Civil Engineering, East China Jiaotong University,808 East Shuanggang Road, Nanchang 330013, Jiangxi, China
| | - Chenxi Wu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Bruce Graham
- School of Biomedical Sciences, Charles Sturt University, Boorooma St, Wagga Wagga, NSW 2678, Australia
| | - Philip G Kerr
- School of Biomedical Sciences, Charles Sturt University, Boorooma St, Wagga Wagga, NSW 2678, Australia
| | - Yonghong Wu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences,71 East Beijing Road, Nanjing 210008, China; Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, P. O. Box 875701, Tempe, AZ 85287-5701, USA.
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24
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Bouchet S, Goñi-Urriza M, Monperrus M, Guyoneaud R, Fernandez P, Heredia C, Tessier E, Gassie C, Point D, Guédron S, Achá D, Amouroux D. Linking Microbial Activities and Low-Molecular-Weight Thiols to Hg Methylation in Biofilms and Periphyton from High-Altitude Tropical Lakes in the Bolivian Altiplano. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9758-9767. [PMID: 30037219 DOI: 10.1021/acs.est.8b01885] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The sources and factors controlling concentrations of monomethylmercury (MMHg) in aquatic ecosystems need to be better understood. Here, we investigated Hg transformations in sediments, periphyton associated with green algae's or aquatic plants, and benthic biofilms from the Lake Titicaca hydrosystem and compared them to the occurrence of active methylating microorganisms and extracellular Hg ligands. Intense Hg methylation was found in benthic biofilms and green algae's periphyton, while it remained low in sediments and aquatic plants' periphyton. Demethylation varied between compartments but remained overall in the same range. Hg methylation was mainly carried out by sulfate reducers, although methanogens also played a role. Its variability between compartments was first explained by the presence or absence of the hgcAB genes. Next, both benthic biofilm and green algae's periphyton exhibited a great diversity of extracellular low-molecular-weight (LMW) thiols (13 or 14 compounds) present at a range of a few nmol L-1 or μmol L-1 but clearly dominated by cysteine and 3-mercaptopropionic acid. Hg methylation was overall positively correlated to the total thiol concentrations, albeit to different extents according to the compartment and conditions. This work is the first examining the interplay between active methylating bacterial communities and extracellular ligands in heterotrophic biofilms and supports the involvement of LMW thiols in Hg methylation in real aquatic systems.
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Affiliation(s)
- Sylvain Bouchet
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
| | - Marisol Goñi-Urriza
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
| | - Mathilde Monperrus
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
| | - Rémy Guyoneaud
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
| | - Pablo Fernandez
- Unidad de Calidad Ambiental (UCA) , Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota , Calle 27 , 00000 La Paz , Bolivia
| | - Carlos Heredia
- Unidad de Calidad Ambiental (UCA) , Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota , Calle 27 , 00000 La Paz , Bolivia
| | - Emmanuel Tessier
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
| | - Claire Gassie
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
| | - David Point
- Unidad de Calidad Ambiental (UCA) , Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota , Calle 27 , 00000 La Paz , Bolivia
- Géosciences Environnement Toulouse, UMR5563, IRD UR 234 , Université Paul Sabatier , 14 Avenue Edouard Belin , 31400 Toulouse , France
| | - Stéphane Guédron
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre , 38000 Grenoble , France
- Laboratorio de Hidroquímica , Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota , casilla 3161 , 00000 La Paz , Bolivia
| | - Dario Achá
- Unidad de Calidad Ambiental (UCA) , Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota , Calle 27 , 00000 La Paz , Bolivia
| | - David Amouroux
- CNRS/Univ Pau & Pays Adour , Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux , UMR5254, 64000 , Pau , France
- Unidad de Calidad Ambiental (UCA) , Instituto de Ecologia, Universidad Mayor de San Andres, Campus Universitario de Cota Cota , Calle 27 , 00000 La Paz , Bolivia
- Géosciences Environnement Toulouse, UMR5563, IRD UR 234 , Université Paul Sabatier , 14 Avenue Edouard Belin , 31400 Toulouse , France
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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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Xiang Y, Wang Y, Zhang C, Shen H, Wang D. Water level fluctuations influence microbial communities and mercury methylation in soils in the Three Gorges Reservoir, China. J Environ Sci (China) 2018; 68:206-217. [PMID: 29908740 DOI: 10.1016/j.jes.2018.03.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/03/2018] [Accepted: 03/09/2018] [Indexed: 06/08/2023]
Abstract
Reservoirs tend to have enhanced methylmercury (MeHg) concentrations compared to natural lakes and rivers, and water level fluctuations can promote MeHg production. Until now, little research has been conducted on the effects of microorganisms in soils for the formation of MeHg during different drying and flooding alternating conditions in the Three Gorges Reservoir (TGR). This study aimed to understand how water level fluctuations affect soil microbial composition and mercury concentrations, and if such microbial variations are related to Hg methylation. The results showed that MeHg concentrations and the ratios of MeHg to THg (MeHg%) in soils were higher in the seasonally drying and flooding alternating areas (DFAs, 175-155m) than those in the non-inundated (NIAs, >175m) and inundated areas (IAs, <145m). However, MeHg% in all samples was less than 1%, indicating that the Hg methylation activity in the soils of the TGR was under a low level. 454 high-throughput sequencing of 16S rRNA gene amplicons showed that soil bacterial abundance and diversity were relatively higher in DFA compared to those in NIA and IA, and microbial community composition varied in these three areas. At the family level, those groups in Deltaproteobacteria and Methanomicrobia that might have many Hg methylators were also showed a higher relative abundance in DFA, which might be the reason for the higher MeHg production in these areas. Overall, our results suggested that seasonally water level fluctuations can enhance the microbial abundance and diversity, as well as MeHg production in the TGR.
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Affiliation(s)
- Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Hong Shen
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China.
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China.
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Hsu-Kim H, Eckley CS, Achá D, Feng X, Gilmour CC, Jonsson S, Mitchell CPJ. Challenges and opportunities for managing aquatic mercury pollution in altered landscapes. AMBIO 2018; 47:141-169. [PMID: 29388127 PMCID: PMC5794684 DOI: 10.1007/s13280-017-1006-7] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The environmental cycling of mercury (Hg) can be affected by natural and anthropogenic perturbations. Of particular concern is how these disruptions increase mobilization of Hg from sites and alter the formation of monomethylmercury (MeHg), a bioaccumulative form of Hg for humans and wildlife. The scientific community has made significant advances in recent years in understanding the processes contributing to the risk of MeHg in the environment. The objective of this paper is to synthesize the scientific understanding of how Hg cycling in the aquatic environment is influenced by landscape perturbations at the local scale, perturbations that include watershed loadings, deforestation, reservoir and wetland creation, rice production, urbanization, mining and industrial point source pollution, and remediation. We focus on the major challenges associated with each type of alteration, as well as management opportunities that could lessen both MeHg levels in biota and exposure to humans. For example, our understanding of approximate response times to changes in Hg inputs from various sources or landscape alterations could lead to policies that prioritize the avoidance of certain activities in the most vulnerable systems and sequestration of Hg in deep soil and sediment pools. The remediation of Hg pollution from historical mining and other industries is shifting towards in situ technologies that could be less disruptive and less costly than conventional approaches. Contemporary artisanal gold mining has well-documented impacts with respect to Hg; however, significant social and political challenges remain in implementing effective policies to minimize Hg use. Much remains to be learned as we strive towards the meaningful application of our understanding for stakeholders, including communities living near Hg-polluted sites, environmental policy makers, and scientists and engineers tasked with developing watershed management solutions. Site-specific assessments of MeHg exposure risk will require new methods to predict the impacts of anthropogenic perturbations and an understanding of the complexity of Hg cycling at the local scale.
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Affiliation(s)
- Heileen Hsu-Kim
- Department of Civil & Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, NC 27708 USA
| | - Chris S. Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101 USA
| | - Dario Achá
- Unidad de Calidad Ambiental, Instituto de Ecología, Carrera de Biología, Universidad Mayor de San Andrés, P.O. Box 10077, La Paz, Bolivia
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China
| | - Cynthia C. Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037-0028 USA
| | - Sofi Jonsson
- Department of Environmental Science and Analytical Chemistry, Stockholm University, Svante Arrhenius väg 8, 11418 Stockholm, Sweden
| | - Carl P. J. Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4 Canada
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Bełdowska M, Zgrundo A, Kobos J. Mercury in the Diatoms of Various Ecological Formations. WATER, AIR, AND SOIL POLLUTION 2018; 229:168. [PMID: 29773924 PMCID: PMC5945792 DOI: 10.1007/s11270-018-3814-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 04/24/2018] [Indexed: 05/05/2023]
Abstract
Mercury is a neurotoxin, its main source in the human organism being fish and seafood. The first level in the marine food web is formed of planktonic and benthic photosynthetic microorganisms, which form a biofilm on the surface of the hard bottom (epilithon) or plants (epiphyton). They are carriers of nutritional as well as toxic substances and pass these on to subsequent levels of the trophic web. Their biomass is often dominated by diatoms. This was the basis for the presented study into Hg accumulation in epilithic, epiphytic and planktonic diatoms, which was carried out in 2012-2013 in the coastal zone of the Puck Lagoon and the Gulf of Gdańsk (southern Baltic). In this coastal area, both micro- and macroorganisms develop particularly intensively. The collected results indicate an increase in Hg concentration in the biofilm during the warm season which, with the lengthening of the vegetative period due to global warming in recent years, is of great significance. As a consequence, the annual mercury load entering the trophic web is larger in comparison with a year in which there is a long, cold winter. An important parameter influencing the accumulation of Hg was the function of those organisms from the biofilm-forming communities. In this case, the highest concentrations of Hg were measured in organisms forming high-profile guilds.
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Affiliation(s)
- Magdalena Bełdowska
- Institute of Oceanography, University of Gdańsk, Av. Marszałka Piłsudskiego 46, 81-378 Gdynia, Poland
| | - Aleksandra Zgrundo
- Institute of Oceanography, University of Gdańsk, Av. Marszałka Piłsudskiego 46, 81-378 Gdynia, Poland
| | - Justyna Kobos
- Institute of Oceanography, University of Gdańsk, Av. Marszałka Piłsudskiego 46, 81-378 Gdynia, Poland
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Dranguet P, Le Faucheur S, Slaveykova VI. Mercury bioavailability, transformations, and effects on freshwater biofilms. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:3194-3205. [PMID: 28771825 DOI: 10.1002/etc.3934] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 10/10/2016] [Accepted: 08/01/2017] [Indexed: 05/16/2023]
Abstract
Mercury (Hg) compounds represent an important risk to aquatic ecosystems because of their persistence, bioaccumulation, and biomagnification potential. In the present review, we critically examine state-of-the-art studies on the interactions of Hg compounds with freshwater biofilms, with an emphasis on Hg accumulation, transformations, and effects. Freshwater biofilms contain both primary producers (e.g., algae) and decomposers (e.g., bacteria and fungi), which contribute to both aquatic food webs and the microbial loop. Hence they play a central role in shallow water and streams, and also contribute to Hg trophic transfer through their consumption. Both inorganic and methylated mercury compounds accumulate in biofilms, which could transform them mainly by methylation, demethylation, and reduction. Accumulated Hg compounds could induce diverse metabolic and physiological perturbations in the microorganisms embedded in the biofilm matrix and affect their community composition. The bioavailability of Hg compounds, their transformations, and their effects depend on their concentrations and speciation, ambient water characteristics, biofilm matrix composition, and microorganism-specific characteristics. The basic processes governing the interactions of Hg compounds with biofilm constituents are understudied. The development of novel conceptual and methodological approaches allowing an understanding of the chemo- and biodynamic aspects is necessary to improve the knowledge on Hg cycling in shallow water as well as to enable improved use of freshwater biofilms as potential indicators of water quality and to support better informed risk assessment. Environ Toxicol Chem 2017;36:3194-3205. © 2017 SETAC.
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Affiliation(s)
- Perrine Dranguet
- Faculty of Sciences, School of Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, Switzerland
| | - Séverine Le Faucheur
- Faculty of Sciences, School of Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, Switzerland
| | - Vera I Slaveykova
- Faculty of Sciences, School of Earth and Environment Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, University of Geneva, Geneva, Switzerland
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Gentès S, Taupiac J, Colin Y, André JM, Guyoneaud R. Bacterial periphytic communities related to mercury methylation within aquatic plant roots from a temperate freshwater lake (South-Western France). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:19223-19233. [PMID: 28664497 DOI: 10.1007/s11356-017-9597-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/20/2017] [Indexed: 06/07/2023]
Abstract
Macrophyte floating roots are considered as hotspots for methylmercury (MeHg) production in aquatic ecosystems through microbial activity. Nevertheless, very little is known about periphyton bacterial communities and mercury (Hg) methylators in such ecological niches. The ability to methylate inorganic Hg is broadly distributed among prokaryotes; however, sulfate-reducers have been reported to be the most important MeHg producers in macrophyte floating roots. In the present work, the periphyton bacterial communities colonizing Ludwigia sp. floating roots were investigated through molecular methods. Among the 244 clones investigated, anaerobic microorganisms associated with the sulfur biogeochemical cycle were identified. Notably, members of the sulfur-oxidizing prokaryotes and the anoxygenic, purple non-sulfur bacteria (Rhodobacteraceae, Comamonadaceae, Rhodocyclaceae, Hyphomicrobiaceae) and the sulfate reducers (Desulfobacteraceae, Syntrophobacteraceae, and Desulfobulbaceae) were detected. In addition, 15 sulfate-reducing strains related to the Desulfovibrionaceae family were isolated and their Hg-methylation capacity was tested using a biosensor. The overall results confirmed that Hg methylation is a strain-specific process since the four strains identified as new Hg-methylators were closely related to non-methylating isolates. This study highlights the potential involvement of periphytic bacteria in Hg methylation when favorable environmental conditions are present in such ecological micro-niches.
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Affiliation(s)
- Sophie Gentès
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France.
- Université de Bordeaux, EPOC, UMR CNRS 5805, 33120, Arcachon, France.
| | - Julie Taupiac
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - Yannick Colin
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
| | - Jean-Marc André
- Equipe CIH, IMS UMR 5218, Ecole Nationale Supérieure de Cognitique, 109 Avenue Roul, 33400, Talence, France
| | - Rémy Guyoneaud
- Equipe Environnement et Microbiologie, UMR IPREM5254 Université de Pau et des Pays de l'Adour, Bâtiment IBEAS, BP1153, 64013, Pau Cedex, France
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31
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Zhou C, Cohen MD, Crimmins BA, Zhou H, Johnson TA, Hopke PK, Holsen TM. Mercury Temporal Trends in Top Predator Fish of the Laurentian Great Lakes from 2004 to 2015: Are Concentrations Still Decreasing? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:7386-7394. [PMID: 28578575 DOI: 10.1021/acs.est.7b00982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Mercury (Hg) concentration trends in top predator fish (lake trout and walleye) of the Great Lakes (GL) from 2004 to 2015 were determined by Kendall-Theil robust regression with a cluster-based age normalization method to control for the effect of changes in lake trophic status. When data from the GLs (except Lake Erie) are combined, a significant decreasing trend in the lake trout Hg concentrations was found between 2004 and 2015 with an annual decrease of 4.1% per year, consistent with the decline in regional atmospheric Hg emissions and water Hg concentrations. However, a breakpoint was detected with a significant decreasing slope (-8.1% per year) before the breakpoint (2010), and no trend after the breakpoint. When the lakes are examined individually, Lakes Superior and Huron, which are dominated by atmospheric Hg inputs and are more likely than the lower lakes to respond to declining emissions from areas surrounding the GL, have significant decreasing trends with rates between 5.2 and 7.8% per year from 2004 to 2015. These declining trends appear to be driven by decreasing regional atmospheric Hg emissions although they may be partly counterbalanced by other factors, including increasing local emissions, food web changes, eutrophication, and responses to global climate change. Lakes Michigan, Erie and Ontario may have been more impacted by these other factors and their trends changed from decreasing to non-decreasing or increasing in recent years.
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Affiliation(s)
- Chuanlong Zhou
- Department of Civil and Environmental Engineering, Clarkson University , Potsdam, New York 13676, United States
| | - Mark D Cohen
- Air Resources Laboratory, United States National Oceanic and Atmospheric Administration , College Park, Maryland 20740, United States
| | - Bernard A Crimmins
- Department of Civil and Environmental Engineering, Clarkson University , Potsdam, New York 13676, United States
| | - Hao Zhou
- Institute for a Sustainable Environment, Clarkson University , Potsdam, New York 13676, United States
| | - Timothy A Johnson
- Institute for a Sustainable Environment, Clarkson University , Potsdam, New York 13676, United States
| | - Philip K Hopke
- Institute for a Sustainable Environment, Clarkson University , Potsdam, New York 13676, United States
| | - Thomas M Holsen
- Department of Civil and Environmental Engineering, Clarkson University , Potsdam, New York 13676, United States
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Paranjape AR, Hall BD. Recent advances in the study of mercury methylation in aquatic systems. Facets (Ott) 2017. [DOI: 10.1139/facets-2016-0027] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity, it has become imperative to examine how mercury may enter biotic systems through its methylation to bioavailable forms in aquatic environments. Recent development of stable isotope-based methods in methylation studies has enabled a better understanding of the factors controlling methylation in aquatic systems. In addition, the identification and tracking of the hgcAB gene cluster, which is necessary for methylation, has broadened the range of known methylators and methylation-conducive environments. Study of abiotic factors in methylation with new molecular methods (the use of stable isotopes and genomic methods) has helped elucidate the confounding influences of many environmental factors, as these methods enable the examination of their direct effects instead of merely correlative observations. Such developments will be helpful in the finer characterization of mercury biogeochemical cycles, which will enable better predictions of the potential effects of climate change on mercury methylation in aquatic systems and, by extension, the threat this may pose to biota.
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Affiliation(s)
- Avnee R. Paranjape
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| | - Britt D. Hall
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
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Clayden MG, Lescord GL, Kidd KA, Wang X, Muir DCG, O'Driscoll NJ. Using sulfur stable isotopes to assess mercury bioaccumulation and biomagnification in temperate lake food webs. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:661-670. [PMID: 27648524 DOI: 10.1002/etc.3615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/13/2016] [Accepted: 09/05/2016] [Indexed: 06/06/2023]
Abstract
Nitrogen and carbon stable isotopes (δ15 N, δ13 C) are commonly used to understand mercury (Hg) bioaccumulation and biomagnification in freshwater food webs. Though sulfur isotopes (δ34 S) can distinguish between energy sources from the water column (aqueous sulfate) and from sediments to freshwater organisms, little is known about whether δ34 S can help interpret variable Hg concentrations in aquatic species or food webs. Seven acidic lakes in Kejimkujik National Park (Nova Scotia, Canada) were sampled for biota, water, and sediments in 2009 and 2010. Fishes, zooplankton, and macroinvertebrates were analyzed for δ34 S, δ15 N, δ13 C, and Hg (methyl Hg in invertebrates, total Hg in fishes); aqueous sulfate and profundal sediments were analyzed for δ34 S. Within lakes, mean δ34 S values in sediments and sulfate differed between 0.53‰ and 1.98‰, limiting their use as tracers of energy sources to the food webs. However, log-Hg and δ34 S values were negatively related (slopes -0.14 to -0.35, R2 0.20-0.39, p < 0.001-0.01) through each food web, and slopes were significantly different among lakes (analysis of covariance, lake × δ34 S interaction term p = 0.04). Despite these relationships, multiple regression analyses within each taxon showed that biotic Hg concentrations were generally better predicted by δ15 N and/or δ13 C. The results indicate that δ34 S values are predictive of Hg concentrations in these food webs, although the mechanisms underlying these relationships warrant further study. Environ Toxicol Chem 2017;36:661-670. © 2016 SETAC.
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Affiliation(s)
- Meredith G Clayden
- Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada
| | - Gretchen L Lescord
- Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada
| | - Karen A Kidd
- Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada
| | - Xiaowa Wang
- Aquatic Contaminants Research Division, Canada Centre for Inland Waters, Environment Canada, Burlington, Ontario, Canada
| | - Derek C G Muir
- Aquatic Contaminants Research Division, Canada Centre for Inland Waters, Environment Canada, Burlington, Ontario, Canada
| | - Nelson J O'Driscoll
- Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada
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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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35
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Yang Z, Fang W, Lu X, Sheng GP, Graham DE, Liang L, Wullschleger SD, Gu B. Warming increases methylmercury production in an Arctic soil. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 214:504-509. [PMID: 27131808 DOI: 10.1016/j.envpol.2016.04.069] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 04/18/2016] [Accepted: 04/19/2016] [Indexed: 06/05/2023]
Abstract
Rapid temperature rise in Arctic permafrost impacts not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) toxin that can endanger humans, as well as wildlife in terrestrial and aquatic ecosystems. Currently little is known concerning the effects of rapid permafrost thaw on microbial methylation and how SOC degradation is coupled to MeHg biosynthesis. Here we describe the effects of warming on MeHg production in an Arctic soil during an 8-month anoxic incubation experiment. Net MeHg production increased >10 fold in both organic- and mineral-rich soil layers at warmer (8 °C) than colder (-2 °C) temperatures. The type and availability of labile SOC, such as reducing sugars and ethanol, were particularly important in fueling the rapid initial biosynthesis of MeHg. Freshly amended mercury was more readily methylated than preexisting mercury in the soil. Additionally, positive correlations between mercury methylation and methane and ferrous ion production indicate linkages between SOC degradation and MeHg production. These results show that climate warming and permafrost thaw could potentially enhance MeHg production by an order of magnitude, impacting Arctic terrestrial and aquatic ecosystems by increased exposure to mercury through bioaccumulation and biomagnification in the food web.
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Affiliation(s)
- Ziming Yang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Wei Fang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, China
| | - Xia Lu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Guo-Ping Sheng
- CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, China
| | - David E Graham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Liyuan Liang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Stan D Wullschleger
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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36
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Donovan PM, Blum JD, Singer MB, Marvin-DiPasquale M, Tsui MTK. Isotopic Composition of Inorganic Mercury and Methylmercury Downstream of a Historical Gold Mining Region. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:1691-702. [PMID: 26789018 DOI: 10.1021/acs.est.5b04413] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We measured total mercury (THg) and monomethyl mercury (MMHg) concentrations and mercury (Hg) isotopic compositions in sediment and aquatic organisms from the Yuba River (California, USA) to identify Hg sources and biogeochemical transformations downstream of a historical gold mining region. Sediment THg concentrations and δ(202)Hg decreased from the upper Yuba Fan to the lower Yuba Fan and the Feather River. These results are consistent with the release of Hg during gold mining followed by downstream mixing and dilution. The Hg isotopic composition of Yuba Fan sediment (δ(202)Hg = -0.38 ± 0.17‰ and Δ(199)Hg = 0.04 ± 0.03‰; mean ± 1 SD, n = 7) provides a fingerprint of inorganic Hg (IHg) that could be methylated locally or after transport downstream. The isotopic composition of MMHg in the Yuba River food web was estimated using biota with a range of %MMHg (the percent of THg present as MMHg) and compared to IHg in sediment, algae, and the food web. The estimated δ(202)Hg of MMHg prior to photodegradation (-1.29 to -1.07‰) was lower than that of IHg and we suggest this is due to mass-dependent fractionation (MDF) of up to -0.9‰ between IHg and MMHg. This result is in contrast to net positive MDF (+0.4 to +0.8‰) previously observed in lakes, estuaries, coastal oceans, and forests. We hypothesize that this unique relationship could be due to differences in the extent or pathway of biotic MMHg degradation in stream environments.
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Affiliation(s)
- Patrick M Donovan
- Department of Earth and Environmental Sciences, University of Michigan , 1100 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Joel D Blum
- Department of Earth and Environmental Sciences, University of Michigan , 1100 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Michael Bliss Singer
- Department of Earth and Environmental Sciences, University of St Andrews , North Street, St Andrews, KY16 9AL U.K
- Earth Research Institute, University of California Santa Barbara , Santa Barbara, California 93106 United States
| | | | - Martin T K Tsui
- Department of Biology, University of North Carolina at Greensboro , Greensboro, North Carolina 27402, United States
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Ortiz VL, Mason RP, Ward JE. An examination of the factors influencing mercury and methylmercury particulate distributions, methylation and demethylation rates in laboratory-generated marine snow. MARINE CHEMISTRY 2015; 177:753-762. [PMID: 26644635 PMCID: PMC4669965 DOI: 10.1016/j.marchem.2015.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In the marine environment, settling particulates have been widely studied for their role as effective vertical transporters of nutrients and metals scavenged from the euphotic zone to the benthos. These particulates are composed of transparent exopolymers, plankton and bacterial cells, detritus and organic matter, and form various size fractions from colloids (<0.2μm) to aggregates, and finally marine snow (>300 μm). As marine snow forms in the water column, anoxic layers form around and within the aggregation potentially creating a prime environment for the methylation of mercury (Hg), which occurs primarily in low oxygen environments. To examine this process, marine aggregates were produced from sieved estuarine seawater (100 μm) in 1-L glass bottles spiked with stable isotope enriched methylmercury (CH3199Hg) and inorganic mercury (200Hg(II)) at 18° C using a roller-table. After the rolling period, different particle-size fractions were collected and analyzed, including: visible marine snow (>300μm), particulates 8 to 300 μm, and particulates 0.2 to 8μm. Particulate analysis indicated higher incorporation of both forms of Hg into marine snow compared to unrolled treatments, with greater incorporation of 200Hg(II) than CH3199Hg. In addition, inorganic Hg was methylated and CH3Hg was demethylated in the larger particulate fractions (>8μm). Methylation and demethylation rates were assessed based on changes in isotopic composition of Hg(II) and CH3Hg, and found to be comparable to methylation rates found in sediments. These results indicate that net Hg methylation can occur in marine snow and smaller aggregates in oxic coastal waters, and that this net formation of CH3Hg may be an important source of CH3Hg in both coastal and open ocean surface environments.
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38
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Shangguan H, Liu J, Zhu Y, Tong Z, Wu Y. Start-up of a spiral periphyton bioreactor (SPR) for removal of COD and the characteristics of the associated microbial community. BIORESOURCE TECHNOLOGY 2015; 193:456-462. [PMID: 26162523 DOI: 10.1016/j.biortech.2015.06.151] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 06/28/2015] [Accepted: 06/30/2015] [Indexed: 06/04/2023]
Abstract
Periphyton-based bioreactors are widely accepted for removing various pollutants from wastewater; however, the slow start-up and low efficiency in widely fluctuating temperatures limit its application. A spiral periphyton bioreactor (SPR) was developed and its COD removal capability and the associated microbial communities were investigated. This SPR can be easily backwashed to stimulate periphyton growth and efficiently remove COD at temperatures ranging from 4 to 30 °C. The species richness and evenness of the periphyton community increased during domestication, while its functional diversity and organic carbon metabolic vitality were higher after 30 days domestication. Cyanobacteria were the main components of the SPR and produced an aerobic environment, while Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Sphingobacteria were the microorganisms responsible for COD removal. This study provides valuable insights into changes in pivotal microorganisms of the periphyton community during domestication, and indicates that SPR is simple to operate and efficient in COD removal.
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Affiliation(s)
- Haidong Shangguan
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71, East Beijing Road, Nanjing 210008, PR China
| | - Junzhuo Liu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71, East Beijing Road, Nanjing 210008, PR China; Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium
| | - Yan Zhu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71, East Beijing Road, Nanjing 210008, PR China
| | - Zhengong Tong
- School of Civil Engineering, East China Jiaotong University, 808 Shuang Gang East Road, Nanchang, Jiangxi 330013, PR China
| | - Yonghong Wu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71, East Beijing Road, Nanjing 210008, PR China.
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39
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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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