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Li Z, Wu Z, Bo S, Chi J, Cui X, He W, Cui X, Liu Y, Zhao Y, Tong Y. Role of low-proportion, hydrophobic dissolved organic matter components in inhibiting methylmercury uptake by phytoplankton. Chemosphere 2024; 358:142104. [PMID: 38653399 DOI: 10.1016/j.chemosphere.2024.142104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 04/25/2024]
Abstract
Uptake of methylmercury (MeHg), a potent neurotoxin, by phytoplankton is a major concern due to its role as the primary pathway for MeHg entry into aquatic food webs, thereby posing a significant risk to human health. While it is widely believed that the MeHg uptake by plankton is negatively correlated with the concentrations of dissolved organic matter (DOM) in the water, ongoing debates continue regarding the specific components of DOM that exerts the dominant influence on this process. In this study, we employed a widely-used resin fractionation approach to separate and classify DOM derived from algae (AOM) and natural rivers (NOM) into distinct components: strongly hydrophobic, weakly hydrophobic, and hydrophilic fractions. We conduct a comparative analysis of different DOM components using a combination of spectroscopy and mass spectrometry techniques, aiming to identify their impact on MeHg uptake by Microcystis elabens, a prevalent alga in freshwater environments. We found that the hydrophobic components had exhibited more pronounced spectral characteristics associated with the protein structures while protein-like compounds between hydrophobic and hydrophilic components displayed significant variations in both distributions and the values of m/z (mass-to-charge ratio) of the molecules. Regardless of DOM sources, the low-proportion hydrophobic components usually dominated inhibition of MeHg uptake by Microcystis elabens. Results inferred from the correlation analysis suggest that the uptake of MeHg by the phytoplankton was most strongly and negatively correlated with the presence of protein-like components. Our findings underscore the importance of considering the diverse impacts of different DOM fractions on inhibition of phytoplankton MeHg uptake. This information should be considered in future assessments and modeling endeavors aimed at understanding and predicting risks associated with aquatic Hg contamination.
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Affiliation(s)
- Zhike Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China; School of Resources and Environment, Southwest University of Science and Technology, Mianyang, 621000, China
| | - Zhengyu Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Shao Bo
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Jie Chi
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Xiaoyu Cui
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Wei He
- School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, China
| | - Xiaomei Cui
- Key Laboratory of Biodiversity and Eco-Environmental Protection of the Qinghai-Tibetan Plateau (Ministry of Education), School of Ecology and Environment, Tibet University, Lhasa, 850000, China
| | - Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Yingxin Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Yindong Tong
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China; Key Laboratory of Biodiversity and Eco-Environmental Protection of the Qinghai-Tibetan Plateau (Ministry of Education), School of Ecology and Environment, Tibet University, Lhasa, 850000, China.
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2
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Hansen G, Shumway SE, Mason RP, Baumann Z. A Comparative Study of Mercury Bioaccumulation in Bivalve Molluscs from a Shallow Estuarine Embayment. Arch Environ Contam Toxicol 2024; 86:262-273. [PMID: 38531980 DOI: 10.1007/s00244-024-01058-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/21/2024] [Indexed: 03/28/2024]
Abstract
In estuarine food webs, bivalve molluscs transfer nutrients and pollutants to higher trophic levels. Mercury (Hg) pollution is ubiquitous, but it is especially elevated in estuaries historically impacted by industrial activities, such as those in the U.S. Northeast. Monomethylmercury (MeHg), the organic form of Hg, is highly bioaccumulative and transferable in the food web resulting in the highest concentrations in the largest and oldest marine predators. Patterns of Hg concentrations in marine bivalve molluscs, however, are poorly understood. In this study, inorganic Hg (iHg), MeHg, and the total Hg (THg) in soft tissues of the northern quahogs (Mercenaria mercenaria), eastern oysters (Crassostrea virginica), and ribbed mussels (Geukensia demissa) from eastern Long Island sound, a temperate estuary of the western North Atlantic Ocean was investigated. In all three species, concentrations of THg remained similar between the four sampling months (May, June, July, and September), and were mostly independent of animal size. In quahogs, MeHg and iHg displayed significant (p < 0.05) positive (iHg in May and June) and negative (MeHg in July and September) changes with shell height. Variability in concentrations of THg, MeHg, and iHg, both inter- and intra-specifically was high and greater in quahogs and oysters (THg: 37, 39%, MeHg: 28, 39%, respectively) than in mussels (THg: 13%, MeHg: 20%). The percentage of THg that was MeHg (%MeHg) was also highly variable in the three species (range: 10-80%), highlighting the importance of measuring MeHg and not only THg in molluscs.
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Affiliation(s)
- Gunnar Hansen
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT, 06340, USA
| | - Sandra E Shumway
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT, 06340, USA
| | - Robert P Mason
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT, 06340, USA
| | - Zofia Baumann
- Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT, 06340, USA.
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3
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Shao B, Li Z, Wu Z, Yang N, Cui X, Lin H, Liu Y, He W, Zhao Y, Wang X, Tong Y. Impacts of autochthonous dissolved organic matter on the accumulation of methylmercury by phytoplankton and zooplankton in a eutrophic coastal ecosystem. Environ Pollut 2023; 336:122457. [PMID: 37633436 DOI: 10.1016/j.envpol.2023.122457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 08/28/2023]
Abstract
The bioaccumulation of methylmercury (MeHg) within the pelagic food webs is a crucial determinant of the MeHg concentration in the organisms at higher trophic levels. Dissolved organic matter (DOM) is recognized for its influence on mercury (Hg) cycling in the aquatic environment because of its role in providing metabolic substrate for heterotrophic organism and serving as a strong ligand for MeHg. However, the impact of DOM on MeHg bioaccumulation in pelagic food chains remain controversial. Here, we explored MeHg bioaccumulation within a pelagic food web in China, in the eutrophic Bohai Sea and adjacent seas, covering a range of DOM concentrations and compositions. Our findings show that elevated concentrations of dissolved organic carbon (DOC) and phytoplankton biomass may contribute to a reduction in MeHg uptake by phytoplankton. Moreover, we observe that a higher level of autochthonous DOM in the water may result in more significant MeHg biomagnification in zooplankton. This can be explained by alterations in the structure of pelagic food webs and/or an increase in the direct consumption of DOM and particulate organic matter (POM) containing MeHg. Our study offers direct field monitoring evidence of dual roles played by DOM in regulating MeHg transfers from water to phytoplankton and zooplankton in coastal pelagic food webs. A thorough understanding of the intricate interactions is essential for a more comprehensive evaluation of ecological risks associated with MeHg exposure in coastal ecosystems.
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Affiliation(s)
- Bo Shao
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Zhike Li
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Zhengyu Wu
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Ning Yang
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Xiaoyu Cui
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Huiming Lin
- College of Urban & Environmental Sciences, Peking University, Beijing, 100871, China
| | - Yiwen Liu
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Wei He
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, China
| | - Yingxin Zhao
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China
| | - Xuejun Wang
- College of Urban & Environmental Sciences, Peking University, Beijing, 100871, China
| | - Yindong Tong
- School of Environmental Science & Engineering, Tianjin University, Tianjin, 300072, China; School of Ecology and Environment, Tibet University, Lhasa, 850000, China.
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4
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Seelen E, Liem-Nguyen V, Wünsch U, Baumann Z, Mason R, Skyllberg U, Björn E. Dissolved organic matter thiol concentrations determine methylmercury bioavailability across the terrestrial-marine aquatic continuum. Nat Commun 2023; 14:6728. [PMID: 37872168 PMCID: PMC10593767 DOI: 10.1038/s41467-023-42463-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/11/2023] [Indexed: 10/25/2023] Open
Abstract
The most critical step for methylmercury (MeHg) bioaccumulation in aquatic food webs is phytoplankton uptake of dissolved MeHg. Dissolved organic matter (DOM) has been known to influence MeHg uptake, but the mechanisms have remained unclear. Here we show that the concentration of DOM-associated thiol functional groups (DOM-RSH) varies substantially across contrasting aquatic systems and dictates MeHg speciation and bioavailability to phytoplankton. Across our 20 study sites, DOM-RSH concentrations decrease 40-fold from terrestrial to marine environments whereas dissolved organic carbon (DOC), the typical proxy for MeHg binding sites in DOM, only has a 5-fold decrease. MeHg accumulation into phytoplankton is shown to be directly linked to the concentration of specific MeHg binding sites (DOM-RSH), rather than DOC. Therefore, MeHg bioavailability increases systematically across the terrestrial-marine aquatic continuum as the DOM-RSH concentration decreases. Our results strongly suggest that measuring DOM-RSH concentrations will improve empirical models in phytoplankton uptake studies and will form a refined basis for modeling MeHg incorporation in aquatic food webs under various environmental conditions.
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Affiliation(s)
- Emily Seelen
- University of Connecticut, Department of Marine Sciences, Groton, CT, USA.
- University of Southern California, Earth Sciences, Los Angeles, CA, USA.
| | | | - Urban Wünsch
- Technical University of Denmark, National Institute of Aquatic Resources, Section for Oceans and Arctic, 2800, Lyngby, Denmark
| | - Zofia Baumann
- University of Connecticut, Department of Marine Sciences, Groton, CT, USA
| | - Robert Mason
- University of Connecticut, Department of Marine Sciences, Groton, CT, USA
| | - Ulf Skyllberg
- Swedish University of Agricultural Sciences, Department of Forest Ecology and Management Umeå, Umeå, Sweden
| | - Erik Björn
- Umeå University, Department of Chemistry, Umeå, Sweden.
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5
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Li Z, Wu Z, Shao B, Tanentzap AJ, Chi J, He W, Liu Y, Wang X, Zhao Y, Tong Y. Biodegradability of algal-derived dissolved organic matter and its influence on methylmercury uptake by phytoplankton. Water Res 2023; 242:120175. [PMID: 37301000 DOI: 10.1016/j.watres.2023.120175] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/30/2023] [Accepted: 06/04/2023] [Indexed: 06/12/2023]
Abstract
Methylmercury (MeHg) uptake by phytoplankton represents a key step in determining the exposure risks of aquatic organisms and human beings to this potent neurotoxin. Phytoplankton uptake is believed to be negatively related to dissolved organic matter (DOM) concentration in water. However, microorganisms can rapidly change DOM concentration and composition and subsequent impact on MeHg uptake by phytoplankton has rarely been tested. Here, we explored the influences of microbial degradation on the concentrations and molecular compositions of DOM derived from three common algal sources and tested their subsequent impacts on MeHg uptake by the widespread phytoplankton species Microcystis elabens. Our results indicated that dissolved organic carbon was degraded by 64.3‒74.1% within 28 days of incubating water with microbial consortia from a natural meso‑eutrophic river. Protein-like components in DOM were more readily degraded, while the numbers of molecular formula for peptides-like compounds had increased after 28 days' incubation, probably due to the production and release of bacterial metabolites. Microbial degradation made DOM more humic-like which was consistent with the positive correlations between changes in proportions of Peaks A and C and bacterial abundance in bacterial community structures as illustrated by 16S rRNA gene sequencing. Despite rapid losses of the bulk DOM during the incubation, we found that DOM degraded after 28 days still reduced the MeHg uptake by Microcystis elabens by 32.7‒52.7% relative to a control without microbial decomposers. Our findings emphasize that microbial degradation of DOM would not necessarily enhance the MeHg uptakes by phytoplankton and may become more powerful in inhibiting MeHg uptakes by phytoplankton. The potential roles of microbes in degrading DOM and changing the uptakes of MeHg at the base of food webs should now be incorporated into future risk assessments of aquatic Hg cycling.
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Affiliation(s)
- Zhike Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Zhengyu Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Bo Shao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Andrew J Tanentzap
- Ecosystems and Global Change Group, School of the Environment, Trent University, Peterborough, Ontario K9L 0G2, Canada
| | - Jie Chi
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Wei He
- School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xuejun Wang
- College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Yingxin Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Yindong Tong
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; College of Ecology and Environment, Tibet University, Lhasa 850000, China.
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6
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Li D, Lin H, Guo L. Comparisons in molecular weight distributions and size-dependent optical properties among model and reference natural dissolved organic matter. Environ Sci Pollut Res Int 2023; 30:57638-57652. [PMID: 36971940 DOI: 10.1007/s11356-023-26398-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 03/07/2023] [Indexed: 05/10/2023]
Abstract
Humic acid (HA) and reference natural organic matter (NOM) have been widely used in environmental assessment, biogeochemistry, and ecotoxicity studies. Nevertheless, similarities and differences among the commonly used model/reference NOMs and bulk dissolved organic matter (DOM) have rarely been systematically evaluated. In this study, HA, SNOM (Suwannee River NOM) and MNOM (Mississippi River NOM), both from International Humic Substances Society, and freshly collected unfractionated NOM (FNOM) were concurrently characterized to evaluate their heterogeneous nature and size-dependent chemical properties. We found that molecular weight distributions, PARAFAC-derived fluorescent components, and size-dependent optical properties are NOM-specific and highly variable with pH. The < 1 kDa DOM abundance followed the order of HA < SNOM < MNOM < FNOM. In addition, FNOM was more hydrophilic and contained more protein-like and autochthonous components with a higher UV-absorbance ratio index (URI) and biological fluorescence index, whereas HA and SNOM contained more allochthonous, humic-like components with a higher aromaticity and lower URI. Significant differences in molecular composition and size spectra between FNOM and model/reference NOMs suggest that environmental role of NOMs should be evaluated at the levels of molecular weight and functionalities under the same experimental conditions and that HA and SNOM may not represent bulk NOM in the environment. This study provides new information about similarities and differences in DOM size-spectra and chemical properties between reference NOMs and in-situ NOM and highlights the need to better understand the heterogenous roles of NOMs in regulating the toxicity/bioavailability and environmental fate of pollutants in aquatic environments.
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Affiliation(s)
- Dan Li
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA.
- Ecology School, Shanghai Institute of Technology, Shanghai, 201418, China.
| | - Hui Lin
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA
- Polar Research Institute of China, Shanghai, 200136, China
| | - Laodong Guo
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA
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7
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Li Z, Chi J, Shao B, Wu Z, He W, Liu Y, Sun P, Lin H, Wang X, Zhao Y, Chen L, Tong Y. Inhibition of methylmercury uptake by freshwater phytoplankton in presence of algae-derived organic matter. Environ Pollut 2022; 313:120111. [PMID: 36075338 DOI: 10.1016/j.envpol.2022.120111] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/29/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
As the first step of methylmercury (MeHg) entry into the aquatic food webs, MeHg uptake by phytoplankton is crucial in determining the final human MeHg exposure risks. MeHg availability to plankton is regulated by dissolved organic matter (DOM) in the water, while the extent of the impacts can vary largely based on the sources of DOM. Here, we investigated impacts of DOM sources on MeHg bioconcentration by three freshwater phytoplankton species (i.e. S. quadricauda, Chlorella sp., Microcystis elabens) in the laboratory system. We found that algae-derived DOM would prohibited the cellular MeHg bioconcentration by a percent up to 77-93%, while the soil-derived DOM didn't show similar inhibition effects. DOM characterization by the excitation‒emission matrices, Fourier transform infrared spectrum, ultra‒high performance liquid chromatography‒tandem quadrupole time of flight mass spectrometry shown that the molecular size of S-containing compound, rather than thiol concentration, has played a crucial role in regulating the MeHg uptake by phytoplankton. Climate change and increasing nutrient loadings from human activities may affect plankton growth in the freshwater, ultimately changing the DOM compositions. Impacts of these changes on cellular MeHg uptakes by phytoplankton should be emphasized when exploring the aquatic Hg cycling and evaluating their risks to human beings and wild life.
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Affiliation(s)
- Zhike Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Jie Chi
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Bo Shao
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Zhengyu Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Wei He
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, China
| | - Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Peizhe Sun
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Huiming Lin
- College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Xuejun Wang
- College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Yingxin Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Long Chen
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, China
| | - Yindong Tong
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.
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8
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Janssen SE, Tate MT, Poulin BA, Krabbenhoft DP, DeWild JF, Ogorek JM, Varonka MS, Orem WH, Kline JL. Decadal trends of mercury cycling and bioaccumulation within Everglades National Park. Sci Total Environ 2022; 838:156031. [PMID: 35595135 DOI: 10.1016/j.scitotenv.2022.156031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) contamination has been a persistent concern in the Florida Everglades for over three decades due to elevated atmospheric deposition and the system's propensity for methylation and rapid bioaccumulation. Given declines in atmospheric Hg concentrations in the conterminous United States and efforts to mitigate nutrient release to the greater Everglades ecosystem, it was vital to assess how Hg dynamics responded on temporal and spatial scales. This study used a multimedia approach (water and biota) to examine Hg and methylmercury (MeHg) dynamics across a 76-site network within the southernmost portion of the region, Everglades National Park (ENP), from 2008 to 2018. Hg concentrations across matrices showed that air, water, and biota from the system were inextricably linked. Temporal patterns across matrices were driven primarily by hydrologic and climatic changes in the park and no evidence of a decline in atmospheric Hg deposition from 2008 to 2018 was observed, unlike other regions of the United States. In the Shark River Slough (SRS), excess dissolved organic carbon and sulfate were also consistently delivered from upgradient canals and showed no evidence of decline over the study period. Within the SRS a strong positive correlation was observed between MeHg concentrations in surface water and resident fish. Within distinct geographic regions of ENP (SRS, Marsh, Coastal), the geochemical controls on MeHg dynamics differed and highlighted regions susceptible to higher MeHg bioaccumulation, particularly in the SRS and Coastal regions. This study demonstrates the strong influence that dissolved organic carbon and sulfate loads have on spatial and temporal distributions of MeHg across ENP. Importantly, improved water quality and flow rates are two key restoration targets of the nearly 30-year Everglades restoration program, which if achieved, this study suggests would lead to reduced MeHg production and exposure.
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Affiliation(s)
- Sarah E Janssen
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA.
| | - Michael T Tate
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - Brett A Poulin
- University of California-Davis, Department of Environmental Toxicology, Davis, CA, USA
| | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - John F DeWild
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - Jacob M Ogorek
- U.S. Geological Survey, Upper Midwest Water Science Center, Madison, WI, USA
| | - Matthew S Varonka
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, USA
| | - William H Orem
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, USA
| | - Jeffrey L Kline
- South Florida Natural Resources Center, Everglades National Park, Homestead, FL, USA
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9
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Lu Y, Huang R, Wang J, Wang L, Zhang W. Effects of Polyester Microfibers on the Growth and Toxicity Production of Bloom-Forming Cyanobacterium Microcystis aeruginosa. Water 2022; 14:2422. [DOI: 10.3390/w14152422] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The global pollution of microplastics (MPs) has attracted wide attention, and many studies have been conducted on the effects of MP qualities or types and particle sizes on aquatic organisms. However, few studies on the impact of polyethylene terephthalate microplastic (mPET) with different colors on phytoplankton in aquatic ecosystems have been carried out. In this study, mPET of three common colors (green, black, and white) in different concentrations (0, 10, 50, 100, and 200 mg/L) were selected to explore effects on a bloom-forming cyanobacterium Microcystis aeruginosa. The growth, photosynthesis, the number and size of colony, and MC-LR production of M. aeruginosa were studied within a 25-days exposure experiment. The results showed that colors of mPET had significant effects on the growth and photosynthesis of this species but the concentration of mPET had no significant effect. The low concentration of green mPET group promoted algal growth, photosynthesis, and the M. aeruginosa exposed to it was easier to agglomerate into colonies. Moreover, both mPET colors and concentrations have a significant impact on the microcystin production of M. aeruginosa. The low concentration of the green mPET group significantly inhibited the production throughout the experiment, while the white and black mPET significantly increased the concentration of extracellular microcystin (MC-LR). Our results provided new insights into the effects of MPs with different colors and concentrations on the growth and physiology of cyanobacteria and provide basic data for the ecological risk assessment and pollution prevention of MPs.
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10
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Li ML, Kwon SY, Poulin BA, Tsui MTK, Motta LC, Cho M. Internal Dynamics and Metabolism of Mercury in Biota: A Review of Insights from Mercury Stable Isotopes. Environ Sci Technol 2022; 56:9182-9195. [PMID: 35723432 PMCID: PMC9261262 DOI: 10.1021/acs.est.1c08631] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Monitoring mercury (Hg) levels in biota is considered an important objective for the effectiveness evaluation of the Minamata Convention. While many studies have characterized Hg levels in organisms at multiple spatiotemporal scales, concentration analyses alone often cannot provide sufficient information on the Hg exposure sources and internal processes occurring within biota. Here, we review the decadal scientific progress of using Hg isotopes to understand internal processes that modify the speciation, transport, and fate of Hg within biota. Mercury stable isotopes have emerged as a powerful tool for assessing Hg sources and biogeochemical processes in natural environments. A better understanding of the tissue location and internal mechanisms leading to Hg isotope change is key to assessing its use for biomonitoring. We synthesize the current understanding and uncertainties of internal processes leading to Hg isotope fractionation in a variety of biota, in a sequence of better to less studied organisms (i.e., birds, marine mammals, humans, fish, plankton, and invertebrates). This review discusses the opportunities and challenges of using certain forms of biota for Hg source monitoring and the need to further elucidate the physiological mechanisms that control the accumulation, distribution, and toxicity of Hg in biota by coupling new techniques with Hg stable isotopes.
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Affiliation(s)
- Mi-Ling Li
- School
of Marine Science and Policy, University
of Delaware, 201 Robinson Hall, Newark, Delaware 19716, United
States
| | - Sae Yun Kwon
- Division
of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro,
Nam-Gu, Pohang 37673, South Korea
- Institute
for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, South Korea
| | - Brett A. Poulin
- Department
of Environmental Toxicology, University
of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Martin Tsz-Ki Tsui
- School
of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR 999077, China
| | - Laura C. Motta
- Department
of Chemistry, University at Buffalo, 359 Natural Sciences Complex, Buffalo, New York 14260-3000, United States
| | - Moonkyoung Cho
- Division
of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro,
Nam-Gu, Pohang 37673, South Korea
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11
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Hao YY, Zhu YJ, Yan RQ, Gu B, Zhou XQ, Wei RR, Wang C, Feng J, Huang Q, Liu YR. Important Roles of Thiols in Methylmercury Uptake and Translocation by Rice Plants. Environ Sci Technol 2022; 56:6765-6773. [PMID: 35483101 DOI: 10.1021/acs.est.2c00169] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The bioaccumulation of the neurotoxin methylmercury (MeHg) in rice is a significant concern due to its potential risk to humans. Thiols have been known to affect MeHg bioavailability in microorganisms, but how thiols influence MeHg accumulation in rice plants remains unknown. Here, we investigated effects of common low-molecular-weight thiols, including cysteine (Cys), glutathione (GSH), and penicillamine (PEN), on MeHg uptake and translocation by rice plants. Results show that rice roots can rapidly take up MeHg, and this process is influenced by the types and concentrations of thiols in the system. The presence of Cys facilitated MeHg uptake by roots and translocation to shoots, while GSH could only promote MeHg uptake, but not translocation, by roots. Conversely, PEN significantly inhibited MeHg uptake and translocation to shoots. Using labeled 13Cys assays, we also found that MeHg uptake was coupled with Cys accumulation in rice roots. Moreover, analyses of comparative transcriptomics revealed that key genes associated with metallothionein and SULTR transporter families may be involved in MeHg uptake. These findings provide new insights into the uptake and translocation of MeHg in rice plants and suggest potential roles of thiol attributes in affecting MeHg bioavailability and bioaccumulation in rice.
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Affiliation(s)
- Yun-Yun Hao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Jie Zhu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Ruo-Qun Yan
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xin-Quan Zhou
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Ren-Rui Wei
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Chuang Wang
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiao Feng
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
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12
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Cossa D, Knoery J, Bănaru D, Harmelin-Vivien M, Sonke JE, Hedgecock IM, Bravo AG, Rosati G, Canu D, Horvat M, Sprovieri F, Pirrone N, Heimbürger-Boavida LE. Mediterranean Mercury Assessment 2022: An Updated Budget, Health Consequences, and Research Perspectives. Environ Sci Technol 2022; 56:3840-3862. [PMID: 35244390 DOI: 10.1021/acs.est.1c03044] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mercury (Hg) and especially its methylated species (MeHg) are toxic chemicals that contaminate humans via the consumption of seafood. The most recent UNEP Global Mercury Assessment stressed that Mediterranean populations have higher Hg levels than people elsewhere in Europe. The present Critical Review updates current knowledge on the sources, biogeochemical cycling, and mass balance of Hg in the Mediterranean and identifies perspectives for future research especially in the context of global change. Concentrations of Hg in the Western Mediterranean average 0.86 ± 0.27 pmol L-1 in the upper water layer and 1.02 ± 0.12 pmol L-1 in intermediate and deep waters. In the Eastern Mediterranean, Hg measurements are in the same range but are too few to determine any consistent oceanographical pattern. The Mediterranean waters have a high methylation capacity, with MeHg representing up to 86% of the total Hg, and constitute a source of MeHg for the adjacent North Atlantic Ocean. The highest MeHg concentrations are associated with low oxygen water masses, suggesting a microbiological control on Hg methylation, consistent with the identification of hgcA-like genes in Mediterranean waters. MeHg concentrations are twice as high in the waters of the Western Basin compared to the ultra-oligotrophic Eastern Basin waters. This difference appears to be transferred through the food webs and the Hg content in predators to be ultimately controlled by MeHg concentrations of the waters of their foraging zones. Many Mediterranean top-predatory fish still exceed European Union regulatory Hg thresholds. This emphasizes the necessity of monitoring the exposure of Mediterranean populations, to formulate adequate mitigation strategies and recommendations, without advising against seafood consumption. This review also points out other insufficiencies of knowledge of Hg cycling in the Mediterranean Sea, including temporal variations in air-sea exchange, hydrothermal and cold seep inputs, point sources, submarine groundwater discharge, and exchanges between margins and the open sea. Future assessment of global change impacts under the Minamata Convention Hg policy requires long-term observations and dedicated high-resolution Earth System Models for the Mediterranean region.
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Affiliation(s)
- Daniel Cossa
- Université Grenoble Alpes, ISTerre, CS 40700, 38058 Grenoble Cedex 9, France
| | - Joël Knoery
- Ifremer, Centre Atlantique de Nantes, BP 44311, 44980 Nantes, France
| | - Daniela Bănaru
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 Marseille, France
| | - Mireille Harmelin-Vivien
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 Marseille, France
| | - Jeroen E Sonke
- Géosciences Environnement Toulouse, CNRS/Observatoire Midi-Pyrénées (OMP)/Université de Toulouse, 31400 Toulouse, France
| | - Ian M Hedgecock
- Istituto sull'inquinamento atmosferico, CNR-IIA, 87036 Rende, Italy
| | | | - Ginevra Rosati
- Istituto Nazionale di Oceanografia e di Geofisca Sperimentale (OGS), 34010 Trieste, Italy
| | - Donata Canu
- Istituto Nazionale di Oceanografia e di Geofisca Sperimentale (OGS), 34010 Trieste, Italy
| | | | | | - Nicola Pirrone
- Istituto sull'inquinamento atmosferico, CNR-IIA, 87036 Rende, Italy
| | - Lars-Eric Heimbürger-Boavida
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 Marseille, France
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13
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Santos JP, Mehmeti L, Slaveykova VI. Simple Acid Digestion Procedure for the Determination of Total Mercury in Plankton by Cold Vapor Atomic Fluorescence Spectroscopy. Methods Protoc 2022; 5:mps5020029. [PMID: 35448694 PMCID: PMC9029141 DOI: 10.3390/mps5020029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/21/2022] [Accepted: 03/23/2022] [Indexed: 11/16/2022] Open
Abstract
Plankton, at the bottom of the food web, play a central role in the entry of mercury into the aquatic biota. To investigate their role in mercury uptake, reliable analytical procedures for Hg analysis are highly sought. Wet digestion procedures for determining total mercury in different biological matrices have been established since years, however only few studies focused on planktonic samples. In the present work, a simple and cost-effective wet digestion method was developed for the determination of total mercury in samples of small plankton material using a cold vapor atomic fluorescence spectroscopy (CVAFS). The optimization of the digestion method was achieved by using glass vessels with Teflon caps, low amount of acids (3 mL w/w 65% HNO3 or 3 mL 50% v/v HNO3), a constant temperature of 85 °C, the presence and absence of pre-ultrasound treatment, and a continuous digestion period (12 h). Certified reference materials IAEA-450 (unicellular alga Scenedesmus obliquus) and BRC-414 (plankton matrix) were used to optimize and validate the digestion method. The recovery efficiency of the proposed method for IAEA-450 and BCR-414 (3.1 mg and 21.5 mg) ranged between 94.1 ± 7.6% and 97.2 ± 4.6%. The method displayed a good recovery efficiency and precision for plankton matrices of low size. Thus, allowing better digestion of planktonic samples for mercury analysis using CVAFS techniques.
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14
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Cossart T, Garcia-Calleja J, Worms IAM, Tessier E, Kavanagh K, Pedrero Z, Amouroux D, Slaveykova VI. Species-specific isotope tracking of mercury uptake and transformations by pico-nanoplankton in an eutrophic lake. Environ Pollut 2021; 288:117771. [PMID: 34271517 DOI: 10.1016/j.envpol.2021.117771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
The present study aims to explore the bioaccumulation and biotic transformations of inorganic (iHg) and monomethyl mercury (MMHg) by natural pico-nanoplankton community from eutrophic lake Soppen, Switzerland. Pico-nanoplankton encompass mainly bacterioplankton, mycoplankton and phytoplankton groups with size between 0.2 and 20 μm. Species-specific enriched isotope mixture of 199iHg and 201MMHg was used to explore the accumulation, the subcellular distribution and transformations occurring in natural pico-nanoplankton sampled at 2 different depths (6.6 m and 8.3 m). Cyanobacteria, diatoms, cryptophyta, green algae and heterotrophic microorganisms were identified as the major groups of pico-nanoplankton with diatoms prevailing at deeper samples. Results showed that pico-nanoplankton accumulated both iHg and MMHg preferentially in the cell membrane/organelles, despite observed losses. The ratios between the iHg and MMHg concentrations measured in the membrane/organelles and cytosol were comparable for iHg and MMHg. Pico-nanoplankton demethylate added 201MMHg (~4 and 12% per day depending on cellular compartment), although the involved pathways are to further explore. Comparison of the concentrations of 201iHg formed from 201MMHg demethylation in whole system, medium and whole cells showed that 82% of the demethylation was biologically mediated by pico-nanoplankton. No significant methylation of iHg by pico-nanoplankton was observed. The accumulation of iHg and MMHg and the percentage of demethylated MMHg correlated positively with the relative abundance of diatoms and heterotrophic microorganisms in the pico-nanoplankton, the concentrations of TN, Mg2+, NO3-, NO2-, NH4+ and negatively with the concentrations of DOC, K+, Na+, Ca2+, SO42-. Taken together the results of the present field study confirm the role of pico-nanoplankton in Hg bioaccumulation and demethylation, however further research is needed to better understand the underlying mechanisms and interconnection between heterotrophic and autotrophic microorganisms.
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Affiliation(s)
- Thibaut Cossart
- Environmental Biogeochemistry and Ecotoxicology, Department F.-A. Forel for Environmental and Aquatic Sciences, Earth and Environmental Sciences, Faculty of Sciences, University of Geneva, Uni Carl Vogt, Bvd Carl-Vogt 66, CH-1211, Geneva 4, Switzerland
| | - Javier Garcia-Calleja
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les matériaux, Pau, France
| | - Isabelle A M Worms
- Environmental Biogeochemistry and Ecotoxicology, Department F.-A. Forel for Environmental and Aquatic Sciences, Earth and Environmental Sciences, Faculty of Sciences, University of Geneva, Uni Carl Vogt, Bvd Carl-Vogt 66, CH-1211, Geneva 4, Switzerland
| | - Emmanuel Tessier
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les matériaux, Pau, France
| | - Killian Kavanagh
- Environmental Biogeochemistry and Ecotoxicology, Department F.-A. Forel for Environmental and Aquatic Sciences, Earth and Environmental Sciences, Faculty of Sciences, University of Geneva, Uni Carl Vogt, Bvd Carl-Vogt 66, CH-1211, Geneva 4, Switzerland
| | - Zoyne Pedrero
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les matériaux, Pau, France
| | - David Amouroux
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les matériaux, Pau, France
| | - Vera I Slaveykova
- Environmental Biogeochemistry and Ecotoxicology, Department F.-A. Forel for Environmental and Aquatic Sciences, Earth and Environmental Sciences, Faculty of Sciences, University of Geneva, Uni Carl Vogt, Bvd Carl-Vogt 66, CH-1211, Geneva 4, Switzerland.
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15
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Gosnell KJ, Dam HG, Mason RP. Mercury and methylmercury uptake and trophic transfer from marine diatoms to copepods and field collected zooplankton. Mar Environ Res 2021; 170:105446. [PMID: 34418733 DOI: 10.1016/j.marenvres.2021.105446] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Mercury (Hg) and methylmercury (CH3Hg) are found at trace levels in most marine waters. These species, particularly CH3Hg, then ominously bioaccumulate through marine food chains eventually reaching potentially harmful levels in top oceanic wildlife. Accordingly, it is important to measure and evaluate uptake at environmentally relevant concentrations where trophic transfer initiates; during uptake in primary producers, and consumption by plankton grazers. Experiments using cultured copepods (Acartia tonsa) and field zooplankton assemblages were performed with two different sized diatom species labeled with stable isotopes of inorganic Hg (200Hg) and CH3Hg (CH3199Hg) at different concentrations. We observed size-specific effects on algal uptake and transfer to copepods, in addition to effects of Hg species concentration. Prey size effects were likewise observed on copepod assimilation efficiencies (AE). Average AE of 200Hg for copepods feeding on smaller diatoms was 50%, and 39% for larger diatoms. The AEs were much greater for CH3199Hg, yielding 71% for the smaller and 88% for the larger diatoms. These experiments add evidence demonstrating a significant relationship between Hg and CH3Hg exposure concentration and subsequent algal uptake and transfer to zooplankton. Furthermore, results imply that facilitated uptake of CH3Hg into algae occurs at low (~pM) concentrations, which has been suggested but not confirmed in previous research.
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Affiliation(s)
- Kathleen J Gosnell
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA.
| | - Hans G Dam
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - Robert P Mason
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
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16
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Janssen SE, Hoffman JC, Lepak RF, Krabbenhoft DP, Walters D, Eagles-Smith CA, Peterson G, Ogorek JM, DeWild JF, Cotter A, Pearson M, Tate MT, Yeardley RB, Mills MA. Examining historical mercury sources in the Saint Louis River estuary: How legacy contamination influences biological mercury levels in Great Lakes coastal regions. Sci Total Environ 2021; 779:146284. [PMID: 33744580 PMCID: PMC9563104 DOI: 10.1016/j.scitotenv.2021.146284] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/01/2021] [Accepted: 03/01/2021] [Indexed: 05/12/2023]
Abstract
Industrial chemical contamination within coastal regions of the Great Lakes can pose serious risks to wetland habitat and offshore fisheries, often resulting in fish consumption advisories that directly affect human and wildlife health. Mercury (Hg) is a contaminant of concern in many of these highly urbanized and industrialized coastal regions, one of which is the Saint Louis River estuary (SLRE), the second largest tributary to Lake Superior. The SLRE has legacy Hg contamination that drives high Hg concentrations within sediments, but it is unclear whether legacy-derived Hg actively cycles within the food web. To understand the relative contributions of legacy versus contemporary Hg sources in coastal zones, Hg, carbon, and nitrogen stable isotope ratios were measured in sediments and food webs of SLRE and the Bad River, an estuarine reference site. Hg stable isotope values revealed that legacy contamination of Hg was widespread and heterogeneously distributed in sediments of SLRE, even in areas lacking industrial Hg sources. Similar isotope values were found in benthic invertebrates, riparian spiders, and prey fish from SLRE, confirming legacy Hg reaches the SLRE food web. Direct comparison of prey fish from SLRE and the Bad River confirmed that Hg isotope differences between the sites were not attributable to fractionation associated with rapid Hg bioaccumulation at estuarine mouths, but due to the presence of industrial Hg within SLRE. The Hg stable isotope values of game fish in both estuaries were dependent on fish migration and diet within the estuaries and extending into Lake Superior. These results indicate that Hg from legacy contamination is actively cycling within the SLRE food web and, through migration, this Hg also extends into Lake Superior via game fish. Understanding sources and the movement of Hg within the estuarine food web better informs restoration strategies for other impaired Great Lakes coastal zones.
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Affiliation(s)
- Sarah E Janssen
- U.S. Geological Survey Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA.
| | - Joel C Hoffman
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA
| | - Ryan F Lepak
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA; Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park Street, Madison, WI 53706, USA
| | - David P Krabbenhoft
- U.S. Geological Survey Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA
| | - David Walters
- U.S. Geological Survey Columbia Environmental Research Center, 4200 New Haven Rd, Columbia, MO 65201, USA
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200SW Jefferson Way, Corvallis, OR 97331, USA
| | - Greg Peterson
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA
| | - Jacob M Ogorek
- U.S. Geological Survey Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA
| | - John F DeWild
- U.S. Geological Survey Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA
| | - Anne Cotter
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA
| | - Mark Pearson
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA
| | - Michael T Tate
- U.S. Geological Survey Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA
| | - Roger B Yeardley
- U.S. Environmental Protection Agency Office of Research and Development, Center for Environmental Solutions and Emergency Response, Cincinnati, OH 45220, USA
| | - Marc A Mills
- U.S. Environmental Protection Agency Office of Research and Development, Center for Environmental Solutions and Emergency Response, Cincinnati, OH 45220, USA
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17
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Kataoka C, Yoshino K, Kashiwada S, Yamamoto M. Do Polystyrene Beads Contribute to Accumulation of Methylmercury in Oysters? Arch Environ Contam Toxicol 2021; 81:36-45. [PMID: 33893852 DOI: 10.1007/s00244-021-00848-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
To clarify whether microplastics contribute to elevated bioaccumulation of methylmercury (MeHg) in aquatic organisms, we studied the sorption pattern of MeHg on polystyrene beads (PBs) and evaluated MeHg accumulation, via uptake of MeHg-adsorbed PB, in the oyster Crassostrea gigas. MeHg-cysteine conjugates were added to seawater at 10, 100, and 1000 µg/L as Hg. Polystyrene beads (φ = 0.02, 0.2, and 2 µm) were immersed in the seawater for 24 h. The concentrations of total mercury (T-Hg) adsorbed onto the PBs were then measured using the reduction vaporization method. T-Hg concentrations for the PBs with diameters of 0.02, 0.2, and 2 µm were 10.6 ± 0.4, 1.8 ± 0.1, and 1.3 ± 0.1 ng/mg-PBs, respectively, when immersed in 2 mL of MeHg-added seawater (100 µg/L as Hg). Thus, the adsorption efficiency of MeHg onto PBs was higher in the presence of smaller diameter PBs. Next, 1 mg of PBs immersed in 2 mL of seawater containing 100 µg/L of MeHg for 24 h was added to an oyster tank containing 1 L of seawater. The T-Hg concentration of the oysters was measured after 6 h of exposure. No significant difference was found in the T-Hg concentration of oysters in the presence of PBs (0.30 ± 0.01 to 0.37 ± 0.05 ng/mg as dry weight) with MeHg and in the absence of PBs (0.36 ± 0.03 ng/mg as dry weight). Our results suggest that the presence of PBs in seawater has little effect on MeHg uptake by oysters.
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Affiliation(s)
- Chisato Kataoka
- National Institute for Minamata Disease as Research Fellow of the Japan Society for the Promotion of Science, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan.
- Department of Environment and Public Health, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan.
- Research Centre for Life and Environmental Sciences, Toyo University, 1-1-1 Izumino, Itakura, Gunma, 374-0193, Japan.
| | - Kenji Yoshino
- Department of Environment and Public Health, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan
| | - Shosaku Kashiwada
- Research Centre for Life and Environmental Sciences, Toyo University, 1-1-1 Izumino, Itakura, Gunma, 374-0193, Japan
- Department of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura, Gunma, 374-0193, Japan
| | - Megumi Yamamoto
- Department of Environment and Public Health, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan
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18
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Pavoni E, García-ordiales E, Covelli S, Cienfuegos P, Roqueñí N. Legacy of Past Mining Activity Affecting the Present Distribution of Dissolved and Particulate Mercury and Methylmercury in an Estuarine Environment (Nalón River, Northern Spain). Applied Sciences 2021; 11:4396. [DOI: 10.3390/app11104396] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
At the Nalón River estuary (Asturias, Northern Spain), the occurrence of Hg is due to historical mining activity which has resulted in environmental issues of great concern. Although several studies have investigated the sediment compartment regarding Hg contamination, no information is currently available on the fate of Hg and MeHg in the water column. Considering different hydrodynamic/seasonal conditions, water samples were collected along the estuary to evaluate Hg and MeHg distribution and partitioning behaviour between solid and aqueous phases. The complementary effect of the river discharge and tidal currents contributed to the prevalence of the dissolved (4.02 ± 1.33 ng L−1) or particulate (8.37 ± 4.20 ng L−1) Hg under different conditions of discharge in summer and autumn, respectively. Conversely, particulate MeHg prevailed when the river flow was low, especially at the estuary mouth (25.8 ± 19.1 pg L−1) and most likely due to the resuspension of fine particles promoted by a stronger tidal current. In comparison with the total Hg concentration, extremely low amounts of dissolved and particulate MeHg were observed, and strong interactions between MeHg and organic carbon highlighted a negligible risk of increased mobility and potential bioaccumulation of MeHg.
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19
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Skrobonja A, Gojkovic Z, Soerensen AL, Westlund PO, Funk C, Björn E. Uptake Kinetics of Methylmercury in a Freshwater Alga Exposed to Methylmercury Complexes with Environmentally Relevant Thiols. Environ Sci Technol 2019; 53:13757-13766. [PMID: 31682417 DOI: 10.1021/acs.est.9b05164] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cellular uptake of dissolved methylmercury (MeHg) by phytoplankton is the most important point of entry for MeHg into aquatic food webs. However, the process is not fully understood. In this study we investigated the influence of chemical speciation on rate constants for MeHg accumulation by the freshwater green microalga Selenastrum capricornutum. We used six MeHg-thiol complexes with moderate but important structural differences commonly found in the environment. Rate constants for MeHg interactions with cells were determined for the MeHg-thiol treatments and a control assay containing the thermodynamically less stable MeHgOH complex. We found both elevated amounts of MeHg associated with whole cells and higher MeHg association rate constants in the control compared to the thiol treatments. Furthermore, the association rate constants were lower when algae were exposed to MeHg complexes with thiols of larger size and more "branched" chemical structure compared to complexes with simpler structure. The results further demonstrated that the thermodynamic stability and chemical structure of MeHg complexes in the medium is an important controlling factor for the rate of MeHg interactions with the cell surface, but not for the MeHg exchange rate across the membrane. Our results are in line with uptake mechanisms involving formation of MeHg complexes with cell surface ligands prior to internalization.
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Affiliation(s)
| | - Zivan Gojkovic
- Umeå University , Department of Chemistry , SE-901 87 Umeå , Sweden
| | - Anne L Soerensen
- Stockholm University , Department of Environmental Science and Analytical Chemistry , SE-106 97 Stockholm , Sweden
| | | | - Christiane Funk
- Umeå University , Department of Chemistry , SE-901 87 Umeå , Sweden
| | - Erik Björn
- Umeå University , Department of Chemistry , SE-901 87 Umeå , Sweden
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20
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Li D, Xie L, Carvan MJ, Guo L. Mitigative effects of natural and model dissolved organic matter with different functionalities on the toxicity of methylmercury in embryonic zebrafish. Environ Pollut 2019; 252:616-626. [PMID: 31185350 DOI: 10.1016/j.envpol.2019.05.155] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 05/27/2019] [Accepted: 05/30/2019] [Indexed: 06/09/2023]
Abstract
Dissolved organic matter (DOM) occurs ubiquitously in aquatic environments and plays an intrinsic role in altering the chemical speciation and toxicity of methylmercury (MeHg). However, interactions between MeHg and natural DOM remain poorly understood, especially at the functional group level. We report here the mitigative effects of three natural organic matter (NOM) and five model-DOM under different concentrations (0, 1, 3, 10, 30 and 100 mg-C/L) on the toxicity of MeHg in embryonic zebrafish (<4 h post-fertilization, hpf). NOM are those from the Mississippi River, Yukon River, and Suwannee River, while model-DOM include those containing thiosalicylic acid, L-glutathione, dextran, alginic acid, and humic acid. We selected a MeHg concentration (100 n-mol/L) that reduces the survival rate of embryos at 24 hpf by 18% and increases malformations at 72 and 96 hpf. In the presence of DOM, however, the malformation rates induced by MeHg can be mitigated to a different extent depending on DOM concentrations, specific functional groups, and/or specific components. Model DOM with aromatic thiols was the most effective at mitigating the effects of MeHg, followed by L-glutathione, carbohydrates, and humic acid. NOM also mitigated the toxicity of MeHg dependent on their composition and/or effective DOM components as characterized by fluorescence excitation-emission matrix techniques. Specifically, humic-like DOM components are more effective in reducing the MeHg toxicity in the embryonic zebrafish compared to protein-like components. Further studies are needed to elucidate the interactions between DOM and MeHg and the mitigative mechanisms at the molecular level.
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Affiliation(s)
- Dan Li
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA; Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lingtian Xie
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Environmental Theoretical Chemistry, South China Normal University, Guangzhou, 510006, China
| | - Michael J Carvan
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA
| | - Laodong Guo
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, 600 E Greenfield Ave., Milwaukee, WI, 53204, USA.
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Soto Cárdenas C, Queimaliños C, Ribeiro Guevara S, Gerea M, Diéguez MC. The microbial mercury link in oligotrophic lakes: Bioaccumulation by picocyanobacteria in natural gradients of dissolved organic matter. Chemosphere 2019; 230:360-368. [PMID: 31108447 DOI: 10.1016/j.chemosphere.2019.04.186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 06/09/2023]
Abstract
Andean Patagonian lakes are oligotrophic systems characterized by low dissolved organic carbon (DOC) levels and moderate to high Hg concentration that determine naturally high Hg/DOC ratios and bioavailability. In these lakes, microbial food webs are extremely important in Hg trophodynamics, being that the picophytoplankton fraction is a major entrance path of Hg2+ into pelagic food webs. This study analyzed the bioaccumulation of Hg2+ by the picocyanobacteria Synechococcus sp. using the radiotracer 197Hg2+ and water from four Andean Patagonian lakes presenting a natural gradient of DOM concentration and quality. Hg2+ bioaccumulation by Synechococcus was calculated as the uptake of Hg2+ per biovolume unit (volume concentration factor VCF; pL μm-3). Hg uptake showed a wide variation (13 < VCF< 300 pL μm-3) in the natural DOC gradient tested (0.7-4 mg L-1; Hg2+/DOC ratio: 1.8-14 ng mg-1). The bioaccumulation of Hg2+ in Synechococcus decreased exponentially with DOC concentration. Differences in the quality of dissolved organic matter (DOM) among lake water influenced also Hg2+ bioaccumulation. Naturally degraded DOM, with low molecular weight/size, promoted higher Hg uptakes in Synechococcus compared to humic DOM, rich in high molecular weight/size aromatic compounds, that retained Hg in the dissolved phase. In Andean Patagonian lakes picocyanobacteria are pivotal organisms in the Hg cycling, taking dissolved Hg2+ and transferring it to pelagic food webs, as well as fueling the benthic Hg pathway through sedimentation.
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Affiliation(s)
- Carolina Soto Cárdenas
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CCT Patagonia Norte CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina.
| | - Claudia Queimaliños
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CCT Patagonia Norte CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina
| | - Sergio Ribeiro Guevara
- Laboratorio de Análisis por Activación Neutrónica, Comisión Nacional de Energía Atómica, Centro Atómico Bariloche, Av. Bustillo Km 9.5, 8400 Bariloche, Argentina
| | - Marina Gerea
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CCT Patagonia Norte CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina
| | - María C Diéguez
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CCT Patagonia Norte CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina
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Taylor VF, Buckman KL, Seelen EA, Mazrui NM, Balcom PH, Mason RP, Chen CY. Organic carbon content drives methylmercury levels in the water column and in estuarine food webs across latitudes in the Northeast United States. Environ Pollut 2019; 246:639-649. [PMID: 30605819 PMCID: PMC6363875 DOI: 10.1016/j.envpol.2018.12.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 05/21/2023]
Abstract
Estuaries are dynamic ecosystems which vary widely in loading of the contaminant methylmercury (MeHg), and in environmental factors which control MeHg exposure to the estuarine foodweb. Inputs of organic carbon and rates of primary production are important influences on MeHg loading and bioaccumulation, and are predicted to increase with changes in climate and land use pressures. To further understand these influences on MeHg levels in estuarine biota, we used a field study approach in sites across different temperature regions, and with varying organic carbon levels. In paired comparisons of sites with high vs. low organic carbon, fish had lower MeHg bioaccumulation factors (normalized to water concentrations) in high carbon sites, particularly subsites with large coastal wetlands and large variability in dissolved organic carbon levels in the water column. Across sites, MeHg level in the water column was strongly tied to dissolved organic carbon, and was the major driver of MeHg concentrations in fish and invertebrates. Higher primary productivity (chlorophyll-a) was associated with increased MeHg partitioning to suspended particulates, but not to the biota. These findings suggest that increased inputs of MeHg and loss of wetlands associated with climate change and anthropogenic land use pressure will increase MeHg concentrations in estuarine food webs.
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Affiliation(s)
- V F Taylor
- Department of Earth Science, Dartmouth College, Hanover, NH, USA.
| | - K L Buckman
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - E A Seelen
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - N M Mazrui
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - P H Balcom
- Harvard John A. Paulson School of Engineering & Applied Sciences, Cambridge, MA, USA
| | - R P Mason
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - C Y Chen
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
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Soto Cárdenas C, Gerea M, Queimaliños C, Ribeiro Guevara S, Diéguez MC. Inorganic mercury (Hg 2+) accumulation in autotrophic and mixotrophic planktonic protists: Implications for Hg trophodynamics in ultraoligotrophic Andean Patagonian lakes. Chemosphere 2018; 199:223-231. [PMID: 29438950 DOI: 10.1016/j.chemosphere.2018.02.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/26/2018] [Accepted: 02/06/2018] [Indexed: 06/08/2023]
Abstract
Microbial assemblages are typical of deep ultraoligotrophic Andean Patagonian lakes and comprise picoplankton and protists (phytoflagellates and mixotrophic ciliates), having a central role in the C cycle, primary production and in the incorporation of dissolved inorganic mercury (Hg2+) into lake food webs. In this study we evaluated the mechanisms of Hg2+ incorporation in hetero- and autotrophic bacteria, in the autotrophic dinoflagellate (Gymnodinium paradoxum) and in two mixotrophic ciliates (Stentor araucanus and Ophrydium naumanni) dominating the planktonic microbial assemblage. The radioisotope 197Hg was used to trace the Hg2+ incorporation in microbiota. Hg uptake was analyzed as a function of cell abundance (BCF: bioconcentration factor), cell surface (SCF: surface concentration factor) and cell volume (VCF: volume concentration factor). Overall, the results obtained showed that these organisms incorporate substantial amounts of dissolved Hg2+ passively (adsorption) and actively (bacteria consumption or attachment), displaying different Hg internalization and therefore, varying potential for Hg transfer. Surface area and quality, and surface:volume ratio (S:V) control the passive uptake in all the organisms. Active incorporation depends on bacteria consumption in the mixotrophic ciliates, or on bacteria association to surface in the autotrophic dinoflagellate. Hg bioaccumulated by pelagic protists can be transferred to higher trophic levels through plankton and fish feeding, regenerated to the dissolved phase by excretion, and/or transferred to the sediments by particle sinking. In ultraoligotrophic Andean Patagonian lakes, picoplankton and planktonic protists are key components of lake food webs, linking the pelagic and benthic Hg pathways, and thereby playing a central role in Hg trophodynamics.
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Affiliation(s)
- Carolina Soto Cárdenas
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina.
| | - Marina Gerea
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina
| | - Claudia Queimaliños
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina
| | - Sergio Ribeiro Guevara
- Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, CNEA, Av. Bustillo Km 9.5, 8400, San Carlos de Bariloche, Río Negro, Argentina
| | - María C Diéguez
- Grupo de Ecología de Sistemas Acuáticos a Escala de Paisaje, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400, San Carlos de Bariloche, Río Negro, Argentina
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24
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Schartup AT, Qureshi A, Dassuncao C, Thackray CP, Harding G, Sunderland EM. A Model for Methylmercury Uptake and Trophic Transfer by Marine Plankton. Environ Sci Technol 2018; 52:654-662. [PMID: 29227685 DOI: 10.1021/acs.est.7b03821] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Methylmercury (MeHg) concentrations can increase by 100 000 times between seawater and marine phytoplankton, but levels vary across sites. To better understand how ecosystem properties affect variability in planktonic MeHg concentrations, we develop a model for MeHg uptake and trophic transfer at the base of marine food webs. The model successfully reproduces measured concentrations in phytoplankton and zooplankton across diverse sites from the Northwest Atlantic Ocean. Highest MeHg concentrations in phytoplankton are simulated under low dissolved organic carbon (DOC) concentrations and ultraoligotrophic conditions typical of open ocean regions. This occurs because large organic complexes bound to MeHg inhibit cellular uptake and cell surface area to volume ratios are greatest under low productivity conditions. Modeled bioaccumulation factors for phytoplankton (102.4-105.9) are more variable than those for zooplankton (104.6-106.2) across ranges in DOC (40-500 μM) and productivities (ultraoligotrophic to hypereutrophic) typically found in marine ecosystems. Zooplankton growth dilutes their MeHg body burden, but they also consume greater quantities of MeHg enriched prey at larger sizes. These competing processes lead to lower variability in MeHg concentrations in zooplankton compared to phytoplankton. Even under hypereutrophic conditions, modeled growth dilution in marine zooplankton is insufficient to lower their MeHg concentrations, contrasting findings from freshwater ecosystems.
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Affiliation(s)
- Amina T Schartup
- Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Harvard University , Boston, Massachusetts 02214, United States
| | - Asif Qureshi
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Harvard University , Boston, Massachusetts 02214, United States
- Department of Civil Engineering, IIT Hyderabad , Kandi, Sangareddy, TS 502285, India
| | - Clifton Dassuncao
- Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Harvard University , Boston, Massachusetts 02214, United States
| | - Colin P Thackray
- Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Gareth Harding
- Bedford Institute of Oceanography , Dartmouth, NS B2Y 4A2, Canada
| | - Elsie M Sunderland
- Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Harvard University , Boston, Massachusetts 02214, United States
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