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Chen Y, Zhang Q, Zhang L, Liu X, Li Y, Liu R, Wang Y, Song Y, Li Y, Yin Y, Cai Y. Light-induced degradation of dimethylmercury in different natural waters. JOURNAL OF HAZARDOUS MATERIALS 2024; 470:134113. [PMID: 38565021 DOI: 10.1016/j.jhazmat.2024.134113] [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: 12/05/2023] [Revised: 02/20/2024] [Accepted: 03/21/2024] [Indexed: 04/04/2024]
Abstract
Photo-induced degradation of dimethylmercury (DMHg) is considered to be an important source for the generation of methylmercury (MMHg). However, studies on DMHg photodegradation are scarce, and it is even debatable about whether DMHg can be degraded in natural waters. Herein, we found that both DMHg and MMHg could be photodegraded in three natural waters collected from the Yellow River Delta, while in pure water only DMHg photodegradation occurred under visible light irradiation. The effects of different environmental factors on DMHg photodegradation were investigated, and the underlying mechanisms were elucidated by density functional theory calculations and a series of control experiments. Our findings revealed that the DMHg degradation rate was higher in the tidal creek water compared to Yellow River, Yan Lake, and purified water. NO3-, NO2-, and DOM could promote the photodegradation with DOM and NO3- showing particularly strong positive effects. Different light sources were employed, and UV light was found to be more effective in DMHg photodegradation. Moreover, MMHg was detected during the photodegradation of DMHg, confirming that the photochemical demethylation of DMHg is a source of MMHg in sunlit water. This work may provide a novel mechanistic insight into the DMHg photodegradation in natural waters and enrich the study of the global biogeochemical cycle of Hg.
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Affiliation(s)
- Yingying Chen
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Qingzhe Zhang
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China; Shenzhen Research Institute, Shandong University, Shenzhen 518057, China.
| | - Lian Zhang
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China
| | - Xinning Liu
- Environment Research Institute, Shandong University, Qingdao 266237, China; Yantai Port United General Wharf Company, Yantai 264012, China
| | - Yanwei Li
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Runzeng Liu
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yingjun Wang
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yue Song
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yanbin Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Yongguang Yin
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Cai
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China; Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199, United States.
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2
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Chen Y, Zhang Q, Zhang L, Wang Y, Song Y, Li Y, Yin Y, Cai Y. An improved method for rapid and safe preparation and measurement of dimethylmercury using gas chromatography-atomic fluorescence spectrometry. J Chromatogr A 2023; 1712:464472. [PMID: 37924619 DOI: 10.1016/j.chroma.2023.464472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/17/2023] [Accepted: 10/22/2023] [Indexed: 11/06/2023]
Abstract
Transformations between dimethylmercury (DMHg) and other mercury (Hg) species have been one of the critical knowledge gaps in the Hg global biogeochemical cycle due to the lack of detailed studies. The preparation and measurement of DMHg are challenging due to the high toxicity and volatility of DMHg. In this work, we invented a new DMHg generator for successfully preparing high-purity DMHg in a highly controllable and safe way. The DMHg could be spontaneously volatilized and diffused from the original preparation solution to the solution to be studied. The parameters for generating DMHg were optimized to be the pH value of 4.0 with a MeCo/Hg2+ molar ratio of 10 at 20 °C. The following measurement method of DMHg in the presence of various species of Hg was also investigated and optimized. Hg0 and DMHg could be separated effectively with the carrier gas flow rate of 15 mL min-1 and the gas chromatography column temperature of 30 °C. The interferences of Hg0, monomethylmercury and other species were excluded by systematic control experiments. A sensitive and reliable approach for quantifying trace DMHg in water was developed. Under the optimal conditions, the limits of detection for Hg0, MMHg and DMHg were 0.03, 0.002 and 0.024 ng L-1, respectively, with the relative standard deviation below 8.2%. The developed method was validated by the determination Hg species of different natural water samples. This work is expected to provide a new and safe strategy for DMHg preparation and a verified method for DMHg measurement.
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Affiliation(s)
- Yingying Chen
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Qingzhe Zhang
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
| | - Lian Zhang
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yingjun Wang
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yue Song
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yanbin Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Yongguang Yin
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Cai
- Shandong Key Laboratory of Environmental Processes and Health, Qingdao Key Laboratory of Marine Pollutant Prevention, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China; Department of Chemistry & Biochemistry, Florida International University, Miami, FL 33199, United States.
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3
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Jonsson S, Mastromonaco MN, Wang F, Bravo AG, Cairns WRL, Chételat J, Douglas TA, Lescord G, Ukonmaanaho L, Heimbürger-Boavida LE. Arctic methylmercury cycling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 850:157445. [PMID: 35882324 DOI: 10.1016/j.scitotenv.2022.157445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Anthropogenic mercury (Hg) undergoes long-range transport to the Arctic where some of it is transformed into methylmercury (MeHg), potentially leading to high exposure in some Arctic inhabitants and wildlife. The environmental exposure of Hg is determined not just by the amount of Hg entering the Arctic, but also by biogeochemical and ecological processes occurring in the Arctic. These processes affect MeHg uptake in biota by regulating the bioavailability, methylation and demethylation, bioaccumulation and biomagnification of MeHg in Arctic ecosystems. Here, we present a new budget for pools and fluxes of MeHg in the Arctic and review the scientific advances made in the last decade on processes leading to environmental exposure to Hg. Methylation and demethylation are key processes controlling the pool of MeHg available for bioaccumulation. Methylation of Hg occurs in diverse Arctic environments including permafrost, sediments and the ocean water column, and is primarily a process carried out by microorganisms. While microorganisms carrying the hgcAB gene pair (responsible for Hg methylation) have been identified in Arctic soils and thawing permafrost, the formation pathway of MeHg in oxic marine waters remains less clear. Hotspots for methylation of Hg in terrestrial environments include thermokarst wetlands, ponds and lakes. The shallow sub-surface enrichment of MeHg in the Arctic Ocean, in comparison to other marine systems, is a possible explanation for high MeHg concentrations in some Arctic biota. Bioconcentration of aqueous MeHg in bacteria and algae is a critical step in the transfer of Hg to top predators, which may be dampened or enhanced by the presence of organic matter. Variable trophic position has an important influence on MeHg concentrations among populations of top predator species such as ringed seal and polar bears distributed across the circumpolar Arctic. These scientific advances highlight key processes that affect the fate of anthropogenic Hg deposited to Arctic environments.
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Affiliation(s)
- Sofi Jonsson
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden.
| | | | - Feiyue Wang
- Centre for Earth Observation Science, and Department of Environment and Geography, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
| | - Warren R L Cairns
- CNR Institute of Polar Sciences and Ca' Foscari University, Venice, Italy
| | - John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, ON, Canada
| | - Thomas A Douglas
- U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK, USA
| | - Gretchen Lescord
- Wildlife Conservation Society Canada and Laurentian University, Vale Living with Lakes Center, Sudbury, Ontario, Canada
| | - Liisa Ukonmaanaho
- Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00791 Helsinki, Finland
| | - Lars-Eric Heimbürger-Boavida
- CNRS/INSU,Aix Marseille Université,Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO), Marseille, France
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Kim J, Kwon SY, Kim K, Han S. Import, export, and speciation of mercury in Kongsfjorden, Svalbard: Influences of glacier melt and river discharge. MARINE POLLUTION BULLETIN 2022; 179:113693. [PMID: 35525059 DOI: 10.1016/j.marpolbul.2022.113693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 04/07/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
The major sources and sinks of total mercury (THg) and methylmercury (MeHg) in Kongsfjorden were estimated based on spreadsheet-based ecological risk assessment for the fate of mercury (SERAFM). SERAFM was parameterized and calibrated to fit Kongsfjorden using the physical properties of the fjord, runoff coefficients of Hg, transformation rate constants of Hg, partition coefficients of Hg, Hg loadings from freshwater, and solid balance parameters. The modeled Hg concentrations in the seawater matched with the measured concentrations, with a mean bias of 12% and a calibration error of 0.035. The mass budget showed that the major THg sources were tidal inflow and glacial runoff, while the major MeHg sources were tidal inflow and in situ methylation in shallow halocline water, which agreed with the distributions of THg and MeHg in seawater. The coupling of observation and fate modeling in Kongsfjorden provides a basic understanding of Hg cycles in the Arctic fjords.
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Affiliation(s)
- Jihee Kim
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Kitae Kim
- Korea Polar Research Institute (KOPRI), Incheon 21990, Republic of Korea; Department of Polar Science, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Seunghee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
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5
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Varty S, Lehnherr I, St Pierre K, Kirk J, Wisniewski V. Methylmercury Transport and Fate Shows Strong Seasonal and Spatial Variability along a High Arctic Freshwater Hydrologic Continuum. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:331-340. [PMID: 33356178 DOI: 10.1021/acs.est.0c05051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The presence of toxic methylmercury (MeHg) in Arctic freshwater ecosystems and foodwebs is a potential health concern for northern Indigenous people. Addressing this issue requires a better understanding of MeHg production, fate during transport, and uptake into foodwebs. We used methylation assays and spatiotemporal surveys of MeHg concentrations, during the ice-covered and open water seasons, across a hydrologic continuum (composed of thaw seeps, lake/ponds, and a wetland) to identify Hg methylation hotspots and seasonal differences in MeHg cycling unique to Arctic ecosystems. Ponds and saturated wetland soils support methylation hotspots during the open water season, but subsequent export of MeHg to downstream ecosystems is limited by particle settling, binding of MeHg on soil organic matter, and/or demethylation in drier wetland soils. During the ice-covered season, MeHg concentrations in lake waters were approximately ten-fold greater than in summer; however, zooplankton MeHg concentrations were paradoxically five times lower at this time. Despite limited evidence of snow-phase methylation, the snowpack is an important MeHg reservoir. Changes in ice-cover duration will alter MeHg production and bioaccumulation in lakes, while increased thaw and surface water flow will likely result in higher methylation rates at the aquatic-terrestrial interface and more efficient downstream transport of MeHg.
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Affiliation(s)
- Stephanie Varty
- Department of Geography, Geomatics and Environment, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Igor Lehnherr
- Department of Geography, Geomatics and Environment, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Kyra St Pierre
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
| | - Jane Kirk
- Canada Centre for Inland Waters, Environment and Climate Change Canada, Burlington, Ontario L7S 1A1, Canada
| | - Victoria Wisniewski
- Department of Geography, Geomatics and Environment, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
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6
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Biotransformation fate and sustainable mitigation of a potentially toxic element of mercury from environmental matrices. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2020.06.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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7
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Tada Y, Marumoto K, Takeuchi A. Nitrospina-Like Bacteria Are Potential Mercury Methylators in the Mesopelagic Zone in the East China Sea. Front Microbiol 2020; 11:1369. [PMID: 32719662 PMCID: PMC7347909 DOI: 10.3389/fmicb.2020.01369] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 05/27/2020] [Indexed: 11/18/2022] Open
Abstract
In natural environments, the production of neurotoxic and bioaccumulative methylmercury (MeHg) is mediated by microorganisms carrying the genes hgcA and hgcB. However, the contribution of these microorganisms to mercury (Hg) methylation or MeHg accumulation in the ocean is poorly understood. Here we determined the total Hg (THg) and MeHg concentrations in seawater samples and conducted a metagenomic survey of the hgcAB genes and functional modules involved in metabolic pathways in the East China Sea (ECS). In the metagenomic analyses, we used paired-end reads and assembled contigs for hgcAB enumeration and phylogenetic analyses in the seawater column. To evaluate the relative abundance of hgcAB in the metagenomic data, we estimated the abundance of recA (single-copy gene of bacteria) as well and then compared them. Moreover, the profiles of prokaryotic community composition were analyzed by 16S rRNA gene (V4 region) deep-sequencing. In the mesopelagic layers, the hgcA sequences were detected, and there was a positive correlation between hgcA abundance relative to the recA and MeHg concentrations. Thus, the quantification of the hgcA sequences could provide valuable information to evaluate the potential environments of microbial MeHg accumulation in the seawater column. A phylogenetic analysis using the assembled contigs revealed that all of the hgcA sequences in the mesopelagic layers were affiliated with Nitrospina-like sequences. The 16S rRNA gene analysis revealed that Nitrospinae were abundant in the mesopelagic layers. Although the lineages of Deltaproteobacteria, Firmicutes, and Spirochaetes were detected in the seawater column, their hgcAB sequences were not detected in our metagenomes, despite the fact that they are closely related to previously identified Hg methylators. The metabolic pathway analysis revealed that the modules related to sulfur and methane metabolism were prominent in the mesopelagic layers. However, no hgcA sequences affiliated with sulfate-reducing bacteria (SRB) or methanogens were detected in these layers, suggesting that these bacteria could not be strongly involved in the Hg accumulation in the seawater column. Our results indicate that Nitrospina-like bacteria with hgcAB genes could play a critical role in microbial Hg accumulation in the oxygenated mesopelagic layers of the ECS.
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Affiliation(s)
- Yuya Tada
- Department of Environment and Public Health, National Institute for Minamata Disease, Kumamoto, Japan
| | - Kohji Marumoto
- Department of Environment and Public Health, National Institute for Minamata Disease, Kumamoto, Japan
| | - Akinori Takeuchi
- Center for Environmental Measurement and Analysis, National Institute for Environmental Studies, Ibaraki, Japan
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Tang WL, Liu YR, Guan WY, Zhong H, Qu XM, Zhang T. Understanding mercury methylation in the changing environment: Recent advances in assessing microbial methylators and mercury bioavailability. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 714:136827. [PMID: 32018974 DOI: 10.1016/j.scitotenv.2020.136827] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/17/2020] [Accepted: 01/18/2020] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) is a neurotoxin, mainly derived from microbial mercury methylation in natural aquatic environments, and poses threats to human health. Polar regions and paddy soils are potential hotspots of mercury methylation and represent environmental settings that are susceptible to natural and anthropogenic perturbations. The effects of changing environmental conditions on the methylating microorganisms and mercury speciation due to global climate change and farming practices aimed for sustainable agriculture were discussed for polar regions and paddy soils, respectively. To better understand and predict microbial mercury methylation in the changing environment, we synthesized current understanding of how to effectively identify active mercury methylators and assess the bioavailability of different mercury species for methylation. The application of biomarkers based on the hgcAB genes have demonstrated the occurrence of potential mercury methylators, such as sulfate-reducing bacteria, iron-reducing bacteria, methanogen and syntrophs, in a diverse variety of microbial habitats. Advanced techniques, such as enriched stable isotope tracers, whole-cell biosensor and diffusive gradient thin film (DGT) have shown great promises in quantitatively assessing mercury availability to microbial methylators. Improved understanding of the complex structure of microbial communities consisting mercury methylators and non-methylators, chemical speciation of inorganic mercury under geochemically relevant conditions, and the pathway of cellular mercury uptake will undoubtedly facilitate accurate assessment and prediction of in situ microbial mercury methylation.
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Affiliation(s)
- Wen-Li Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Yu-Rong Liu
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Wen-Yu Guan
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario K9L 0G2, Canada
| | - Xiao-Min Qu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China.
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Sharma Ghimire P, Tripathee L, Zhang Q, Guo J, Ram K, Huang J, Sharma CM, Kang S. Microbial mercury methylation in the cryosphere: Progress and prospects. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 697:134150. [PMID: 32380618 DOI: 10.1016/j.scitotenv.2019.134150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/20/2019] [Accepted: 08/26/2019] [Indexed: 06/11/2023]
Abstract
Mercury (Hg) is one of the most toxic heavy metals, and its cycle is mainly controlled by oxidation-reduction reactions carried out by photochemical or microbial process under suitable conditions. The deposition and accumulation of methylmercury (MeHg) in various ecosystems, including the cryospheric components such as snow, meltwater, glaciers, and ice sheet, and subsequently in the food chain pose serious health concerns for living beings. Unlike the abundance of knowledge about the processes of MeHg production over land and oceans, little is known about the sources and production/degradation rate of MeHg in cryosphere systems. In addition, processes controlling the concentration of Hg and MeHg in the cryosphere remains poorly understood, and filling this scientific gap has been challenging. Therefore, it is essential to study and review the deposition and accumulation by biological, physical, and chemical mechanisms involved in Hg methylation in the cryosphere. This review attempts to address knowledge gaps in understanding processes, especially biotic and abiotic, applicable for Hg methylation in the cryosphere. First, we focus on the variability in Hg concentration and mechanisms of Hg methylation, including physical, chemical, microbial, and biological processes, and transportation in the cryosphere. Then, we elaborate on the mechanism of redox reactions and biotic and abiotic factors controlling Hg methylation and biogeochemistry of Hg in the cryosphere. We also present possible mechanisms of Hg methylation with an emphasis on microbial transformation and molecular function to understand variability in Hg concentration in the cryosphere. Recent advancements in the genetic and physicochemical mechanisms of Hg methylation are also presented. Finally, we summarize and propose a method to study the unsolved issues of Hg methylation in the cryosphere.
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Affiliation(s)
- Prakriti Sharma Ghimire
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; Himalayan Environment Research Institute (HERI), Kathmandu, Nepal
| | - Lekhendra Tripathee
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; Himalayan Environment Research Institute (HERI), Kathmandu, Nepal.
| | - Qianggong Zhang
- Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China
| | - Junming Guo
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China
| | - Kirpa Ram
- Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India
| | - Jie Huang
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China; Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Chhatra Mani Sharma
- Himalayan Environment Research Institute (HERI), Kathmandu, Nepal; Central Department of Environmental Science, Tribhuvan University, Kathmandu, Nepal
| | - Shichang Kang
- State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China.
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10
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Sontag PT, Steinberg DK, Reinfelder JR. Patterns of total mercury and methylmercury bioaccumulation in Antarctic krill (Euphausia superba) along the West Antarctic Peninsula. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 688:174-183. [PMID: 31229815 DOI: 10.1016/j.scitotenv.2019.06.176] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 04/19/2019] [Accepted: 06/11/2019] [Indexed: 06/09/2023]
Abstract
We examined mercury (Hg) accumulation in juvenile and adult subpopulations of Antarctic krill (Euphausia superba) collected west of the Antarctic Peninsula. Samples were collected along a northern cross-shelf transect beginning near Anvers Island and farther south near the sea ice edge in the austral summers of 2011, 2013, 2014, and 2015. Regardless of geographical position, mean concentrations of total Hg and methylmercury (MeHg), the form of Hg that biomagnifies in marine food webs, were significantly higher in juvenile than adult krill in all years. In 2013, juvenile Antarctic krill collected along the coast near Anvers Island had significantly higher MeHg concentrations than krill collected farther offshore, and in 2013 and 2014, coastal juvenile krill exhibited some of the highest MeHg concentrations of all subpopulations sampled. Across all sampling years, collection in northern (sea ice-free) or southern (sea ice edge) transects did not affect MeHg concentrations of juvenile or adult krill, suggesting similar levels and routes of MeHg exposure across the latitudes sampled. Developmental stage, feeding near the coast, and annual variations in sea ice-driven primary and export production were identified as potentially important factors leading to greater MeHg accumulation in juvenile than adult krill. Krill-dependent predators feeding primarily on juveniles may thus accumulate more MeHg than consumers foraging on older krill. These results report MeHg concentrations in Antarctic krill and will be useful for predicting Hg biomagnification in higher-level consumers in this productive Antarctic ecosystem.
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Affiliation(s)
- Philip T Sontag
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA.
| | - Deborah K Steinberg
- Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, VA 23062, USA.
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA.
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Seco J, Xavier JC, Coelho JP, Pereira B, Tarling G, Pardal MA, Bustamante P, Stowasser G, Brierley AS, Pereira ME. Spatial variability in total and organic mercury levels in Antarctic krill Euphausia superba across the Scotia Sea. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 247:332-339. [PMID: 30685674 DOI: 10.1016/j.envpol.2019.01.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 06/09/2023]
Abstract
Total and organic mercury concentrations were determined for males, females and juveniles of Euphausia superba collected at three discrete locations in the Scotia Sea (South Orkney Islands, South Georgia and Antarctic Polar Front) to assess spatial mercury variability in Antarctic krill. There was clear geographic differentiation in mercury concentrations, with specimens from the South Orkney Islands having total mercury concentrations 5 to 7 times higher than Antarctic krill from South Georgia and the Antarctic Polar Front. Mercury did not appear to accumulate with life-stage since juveniles had higher concentrations of total mercury (0.071 μg g-1 from South Orkney Islands; 0.014 μg g-1 from South Georgia) than adults (0.054 μg g-1 in females and 0.048 μg g-1 in males from South Orkney Islands; 0.006 μg g-1 in females and 0.007 μg g-1 in males from South Georgia). Results suggest that females may use egg laying as a mechanism to excrete mercury, with eggs having higher concentrations than the corresponding somatic tissue. Organic mercury makes up a minor percentage of total mercury (15-37%) with the percentage being greater in adults than in juveniles. When compared to euphausiids from other parts of the world, the concentration of mercury in Antarctic krill is within the same range, or higher, highlighting the global distribution of this contaminant. Given the high potential for biomagnification of mercury through food webs, concentrations in Antarctic krill may have deleterious effects on long-lived Antarctic krill predators.
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Affiliation(s)
- José Seco
- Department of Chemistry and CESAM, University of Aveiro, 3810-193, Aveiro, Portugal; Pelagic Ecology Research Group, Scottish Oceans Institute, University of St Andrews, St Andrews, KY16 8LB, UK.
| | - José C Xavier
- British Antarctic Survey, NERC, High Cross, Madingley Road, CB30ET, Cambridge, UK; MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - João P Coelho
- Department of Biology and CESAM, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Bárbara Pereira
- Department of Chemistry and CESAM, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Geraint Tarling
- British Antarctic Survey, NERC, High Cross, Madingley Road, CB30ET, Cambridge, UK
| | - Miguel A Pardal
- CFE - Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Paco Bustamante
- Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-Université de La Rochelle, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
| | - Gabriele Stowasser
- British Antarctic Survey, NERC, High Cross, Madingley Road, CB30ET, Cambridge, UK
| | - Andrew S Brierley
- Pelagic Ecology Research Group, Scottish Oceans Institute, University of St Andrews, St Andrews, KY16 8LB, UK
| | - Maria E Pereira
- Department of Chemistry and CESAM, University of Aveiro, 3810-193, Aveiro, Portugal
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12
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Harding G, Dalziel J, Vass P. Bioaccumulation of methylmercury within the marine food web of the outer Bay of Fundy, Gulf of Maine. PLoS One 2018; 13:e0197220. [PMID: 30011281 PMCID: PMC6047777 DOI: 10.1371/journal.pone.0197220] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/27/2018] [Indexed: 12/02/2022] Open
Abstract
Mercury and methylmercury were measured in seawater and biota collected from the outer Bay of Fundy to better document mercury bioaccumulation in a temperate marine food web. The size of an organism, together with δ13 C and δ15 N isotopes, were measured to interpret mercury levels in biota ranging in size from microplankton (25μm) to swordfish, dolphins and whales. Levels of mercury in seawater were no different with depth and not elevated relative to upstream sources. The δ13 C values of primary producers were found to be inadequate to specify the original energy source of various faunas, however, there was no reason to separate the food web into benthic, demersal and pelagic food chains because phytoplankton has been documented to almost exclusively fuel the ecosystem. The apparent abrupt increase in mercury content from "seawater" to phytoplankton, on a wet weight basis, can be explained from an environmental volume basis by the exponential increase in surface area of smaller particles included in "seawater" determinations. This physical sorption process may be important up to the macroplankton size category dominated by copepods according to the calculated biomagnification factors (BMF). The rapid increase in methylmercury concentration, relative to the total mercury, between the predominantly phytoplankton (<125μm) and the zooplankton categories is likely augmented by gut microbe methylation. Further up the food chain, trophic transfer of methylmercury dominates resulting in biomagnification factors greater than 10 in swordfish, Atlantic bluefin tuna, harbour porpoise, Atlantic white-sided dolphin and common thresher shark. The biomagnification power of the northern Gulf of Maine ecosystem is remarkably similar to that measured in tropical, subtropical, other temperate and arctic oceanic ecozones.
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Affiliation(s)
- Gareth Harding
- Bedford Institute of Oceanography, Department of Fisheries and Oceans, Dartmouth, Nova Scotia, Canada
| | - John Dalziel
- Environment Canada, Dartmouth, Nova Scotia, Canada
| | - Peter Vass
- Bedford Institute of Oceanography, Department of Fisheries and Oceans, Dartmouth, Nova Scotia, Canada
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13
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Mann EA, Ziegler SE, Steffen A, O'Driscoll NJ. Increasing chloride concentration causes retention of mercury in melted Arctic snow due to changes in photoreduction kinetics. J Environ Sci (China) 2018; 68:122-129. [PMID: 29908731 DOI: 10.1016/j.jes.2018.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 12/19/2017] [Accepted: 01/08/2018] [Indexed: 06/08/2023]
Abstract
Mercury (Hg) in the Arctic is a significant concern due to its bioaccumulative and neurotoxic properties, and the sensitivity of Arctic environments. Previous research has found high levels of Hg in snowpacks with high chloride (Cl-) concentrations. We hypothesised that Cl- would increase Hg retention by decreasing Hg photoreduction to Hg(0) in melted Arctic snow. To test this, changes in Hg photoreduction kinetics in melted Alert, NU snow were quantified with changing Cl- concentration and UV intensity. Snow was collected and melted in Teflon bottles in May 2014, spiked with 0-10μg/g Cl-, and irradiated with 3.52-5.78W·m-2 UV (280-400nm) radiation in a LuzChem photoreactor. Photoreduction rate constants (k) (0.14-0.59hr-1) had positive linear relationships with [Cl-], while photoreduced Hg amounts (Hg(II)red) had negative linear relationships with [Cl-] (1287-64pg in 200g melted snow). Varying UV and [Cl-] both altered Hg(II)red amounts, with more efficient Hg stabilisation by Cl- at higher UV intensity, while k can be predicted by Cl- concentration and/or UV intensity, depending on experimental parameters. Overall, with future projections for greater snowpack Cl- loading, our experimental results suggest that more Hg could be delivered to Arctic aquatic ecosystems by melted snow (smaller Hg(II)red expected), but the Hg in the melted snow that is photoreduced may do so more quickly (larger k expected).
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Affiliation(s)
- E A Mann
- Department of Environmental Science, Acadia University, Wolfville, NS, Canada; Environmental Science Programme, Memorial University of Newfoundland, St. John's, NL, Canada.
| | - S E Ziegler
- Environmental Science Programme, Memorial University of Newfoundland, St. John's, NL, Canada
| | - A Steffen
- Environment and Climate Change Canada, Science and Technology Branch, Air Quality Research Division, Toronto, ON, Canada
| | - N J O'Driscoll
- Department of Environmental Science, Acadia University, Wolfville, NS, Canada
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14
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Weiss-Penzias P, Sorooshian A, Coale K, Heim W, Crosbie E, Dadashazar H, MacDonald AB, Wang Z, Jonsson H. Aircraft Measurements of Total Mercury and Monomethyl Mercury in Summertime Marine Stratus Cloudwater from Coastal California, USA. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2527-2537. [PMID: 29401398 DOI: 10.1021/acs.est.7b05395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Water samples from marine stratus clouds were collected during 16 aircraft flights above the Pacific Ocean near the Central California coast during the summer of 2016. These samples were analyzed for total mercury (THg), monomethyl mercury (MMHg), and 32 other chemical species in addition to aerosol physical parameters. The mean concentrations of THg and MMHg in the cloudwater samples were 9.2 ± 6.0 ng L-1 (2.3-33.8 ng L-1) ( N = 97) and 0.87 ± 0.66 ng L-1 (0.17-2.9 ng L-1) ( N = 22), respectively. This corresponds to 9.5% (3-21%) MMHg as a fraction of THg. Low and high nonsea salt calcium ion (nss-Ca2+) concentrations in cloudwater were used to classify flights as "marine" and "continental", respectively. Mean [MMHg]marine was significantly higher ( p < 0.05) than [MMHg]continental consistent with an ocean source of dimethyl Hg (DMHg) to the atmosphere. Mean THg in cloudwater was not significantly different between the two categories, indicating multiple emissions sources. Mean [THg]continental was correlated with pH, CO, NO3-, NH4+, and other trace metals, whereas [THg]marine was correlated with MMHg and Na+. THg concentrations were negatively correlated with altitude, consistent with ocean and land emissions, coupled with removal at the cloud-top due to drizzle formation.
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Affiliation(s)
- Peter Weiss-Penzias
- Department of Microbiology and Environmental Toxicology , University of California at Santa Cruz , Santa Cruz , California 95064 , United States
| | - Armin Sorooshian
- Department of Chemical and Environmental Engineering , University of Arizona , Tucson , Arizona 85721 , United States
- Department of Hydrology and Atmospheric Sciences , University of Arizona , Tucson , Arizona 85721 , United States
| | - Kenneth Coale
- Moss Landing Marine Laboratories , Moss Landing , California 95039 , United States
| | - Wesley Heim
- Moss Landing Marine Laboratories , Moss Landing , California 95039 , United States
| | - Ewan Crosbie
- NASA Langley Research Center , Hampton , Virginia 23666 , United States
| | - Hossein Dadashazar
- Department of Chemical and Environmental Engineering , University of Arizona , Tucson , Arizona 85721 , United States
| | - Alexander B MacDonald
- Department of Chemical and Environmental Engineering , University of Arizona , Tucson , Arizona 85721 , United States
| | - Zhen Wang
- Department of Chemical and Environmental Engineering , University of Arizona , Tucson , Arizona 85721 , United States
| | - Haflidi Jonsson
- Naval Postgraduate School , Monterey , California 93943 , United States
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15
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Chételat J, Richardson MC, MacMillan GA, Amyot M, Poulain AJ. Ratio of Methylmercury to Dissolved Organic Carbon in Water Explains Methylmercury Bioaccumulation Across a Latitudinal Gradient from North-Temperate to Arctic Lakes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:79-88. [PMID: 29172471 DOI: 10.1021/acs.est.7b04180] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We investigated monomethylmercury (MMHg) bioaccumulation in lakes across a 30° latitudinal gradient in eastern Canada to test the hypothesis that climate-related environmental conditions affect the sensitivity of Arctic lakes to atmospheric mercury contamination. Aquatic invertebrates (chironomid larvae, zooplankton) provided indicators of MMHg bioaccumulation near the base of benthic and planktonic food chains. In step with published data showing latitudinal declines in atmospheric mercury deposition in Canada, we observed lower total mercury concentrations in water and sediment of higher latitude lakes. Despite latitudinal declines of inorganic mercury exposure, MMHg bioaccumulation in aquatic invertebrates did not concomitantly decline. Arctic lakes with greater MMHg in aquatic invertebrates either had (1) higher water MMHg concentrations (reflecting ecosystem MMHg production) or (2) low water concentrations of MMHg, dissolved organic carbon (DOC), chlorophyll, and total nitrogen (reflecting lake sensitivity). The MMHg:DOC ratio of surface water was a strong predictor of lake sensitivity to mercury contamination. Bioaccumulation factors for biofilms and seston in Arctic lakes showed more efficient uptake of MMHg in low DOC systems. Environmental conditions associated with low biological production in Arctic lakes and their watersheds increased the sensitivity of lakes to MMHg.
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Affiliation(s)
- John Chételat
- National Wildlife Research Centre, Environment and Climate Change Canada , Ottawa, Ontario, Canada K1A 0H3
| | - Murray C Richardson
- Geography and Environmental Studies, Carleton University , Ottawa, Ontario, Canada K1S 5B6
| | - Gwyneth A MacMillan
- Centre d'études nordiques, Département de sciences biologiques, Université de Montréal , Montréal, Quebec, Canada H2V 2S9
| | - Marc Amyot
- Centre d'études nordiques, Département de sciences biologiques, Université de Montréal , Montréal, Quebec, Canada H2V 2S9
| | - Alexandre J Poulain
- Department of Biology, University of Ottawa , Ottawa, Ontario, Canada K1N 6N5
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16
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Nasr M, Arp PA. Relating Fish Hg to Variations in Sediment Hg, Climate and Atmospheric Deposition. ACTA ACUST UNITED AC 2018. [DOI: 10.4236/ajcc.2018.73024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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17
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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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19
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Gionfriddo CM, Tate MT, Wick RR, Schultz MB, Zemla A, Thelen MP, Schofield R, Krabbenhoft DP, Holt KE, Moreau JW. Microbial mercury methylation in Antarctic sea ice. Nat Microbiol 2016; 1:16127. [PMID: 27670112 DOI: 10.1038/nmicrobiol.2016.127] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 06/29/2016] [Indexed: 11/09/2022]
Abstract
Atmospheric deposition of mercury onto sea ice and circumpolar sea water provides mercury for microbial methylation, and contributes to the bioaccumulation of the potent neurotoxin methylmercury in the marine food web. Little is known about the abiotic and biotic controls on microbial mercury methylation in polar marine systems. However, mercury methylation is known to occur alongside photochemical and microbial mercury reduction and subsequent volatilization. Here, we combine mercury speciation measurements of total and methylated mercury with metagenomic analysis of whole-community microbial DNA from Antarctic snow, brine, sea ice and sea water to elucidate potential microbially mediated mercury methylation and volatilization pathways in polar marine environments. Our results identify the marine microaerophilic bacterium Nitrospina as a potential mercury methylator within sea ice. Anaerobic bacteria known to methylate mercury were notably absent from sea-ice metagenomes. We propose that Antarctic sea ice can harbour a microbial source of methylmercury in the Southern Ocean.
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Affiliation(s)
- Caitlin M Gionfriddo
- School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Michael T Tate
- Wisconsin Water Science Center, US Geological Survey, Middleton, Wisconsin 53562, USA
| | - Ryan R Wick
- Centre for Systems Genomics, University of Melbourne, Victoria 3010, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - Mark B Schultz
- Centre for Systems Genomics, University of Melbourne, Victoria 3010, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - Adam Zemla
- Computation Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 USA
| | - Michael P Thelen
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Robyn Schofield
- School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia
| | - David P Krabbenhoft
- Wisconsin Water Science Center, US Geological Survey, Middleton, Wisconsin 53562, USA
| | - Kathryn E Holt
- Centre for Systems Genomics, University of Melbourne, Victoria 3010, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - John W Moreau
- School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia
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20
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21
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Mann EA, Mallory ML, Ziegler SE, Avery TS, Tordon R, O'Driscoll NJ. Photoreducible Mercury Loss from Arctic Snow Is Influenced by Temperature and Snow Age. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:12120-12126. [PMID: 26371502 DOI: 10.1021/acs.est.5b01589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Mercury (Hg) is an important environmental contaminant, due to its neurotoxicity and ability to bioaccumulate. The Arctic is a mercury-sensitive region, where organisms can accumulate high Hg concentrations. Snowpack mercury photoredox reactions may control how much Hg is transported with melting Arctic snow. This work aimed to (1) determine the significance of temperature combined with UV irradiation intensity and snow age on Hg(0) flux from Arctic snow and (2) elucidate the effect of temperature on snowpack Hg photoreduction kinetics. Using a Teflon flux chamber, snow temperature, UV irradiation, and snow age were found to significantly influence Hg(0) flux from Arctic snow. Cross-correlation analysis results suggest that UV radiation has a direct effect on Hg(0)flux, while temperature may indirectly influence flux. Laboratory experiments determined that temperature influenced Hg photoreduction kinetics when snow approached the melting point (>-2 °C), where the pseudo-first-order reduction rate constant, k, decreased twofold, and the photoreduced Hg amount, Hg(II)red, increased 10-fold. This suggests that temperature influences Hg photoreduction kinetics indirectly, likely by altering the solid:liquid water ratio. These results imply that large mass transfers of Hg from snow to air may take place during the Arctic snowmelt period, altering photoreducible Hg retention and transport with snow meltwater.
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Affiliation(s)
- Erin A Mann
- Department of Earth Science, Memorial University of Newfoundland , St. John's, NL Canada
| | | | - Susan E Ziegler
- Department of Earth Science, Memorial University of Newfoundland , St. John's, NL Canada
| | | | - Rob Tordon
- Air Quality Science Division, Environment Canada , Dartmouth, NS Canada
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22
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St Pierre KA, St Louis VL, Kirk JL, Lehnherr I, Wang S, La Farge C. Importance of open marine waters to the enrichment of total mercury and monomethylmercury in lichens in the Canadian High Arctic. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:5930-5938. [PMID: 25876438 DOI: 10.1021/acs.est.5b00347] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Caribou, which rely on lichens as forage, are a dietary source of monomethylmercury (MMHg) to many of Canada's Arctic Aboriginal people. However, little is understood about the sources of MMHg to lichens in the High Arctic. We quantified MMHg, total mercury (THg) and other chemical parameters (e.g., marine and crustal elements, δ(13)C, δ(15)N, organic carbon, calcium carbonate) in lichen and soil samples collected along transects extending from the coast on Bathurst and Devon islands, Nunavut, to determine factors driving lichen MMHg and THg concentrations in the High Arctic. Lichen MMHg and THg concentrations ranged from 1.41 to 17.1 ng g(-1) and from 36.0 to 361 ng g(-1), respectively. Both were highly enriched over concentrations in underlying soils, indicating a predominately atmospheric source of Hg in lichens. However, MMHg and THg enrichment at coastal sites on Bathurst Island was far greater than on Devon Island. We suggest that this variability can be explained by the proximity of the Bathurst Island transect to several polynyas, which promote enhanced Hg deposition to adjacent landscapes through various biogeochemical processes. This study is the first to clearly show a strong marine influence on MMHg inputs to coastal terrestrial food webs with implications for MMHg accumulation in caribou and the health of the people who depend on them as part of a traditional diet.
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Affiliation(s)
- K A St Pierre
- †Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - V L St Louis
- †Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - J L Kirk
- ‡Aquatic Ecosystem Protection Research Division, Environment Canada, Burlington, Ontario L7R 4A6, Canada
| | - I Lehnherr
- §Department of Geography, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - S Wang
- †Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - C La Farge
- †Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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Dastoor A, Ryzhkov A, Durnford D, Lehnherr I, Steffen A, Morrison H. Atmospheric mercury in the Canadian Arctic. Part II: insight from modeling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:16-27. [PMID: 25604938 DOI: 10.1016/j.scitotenv.2014.10.112] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/28/2014] [Accepted: 10/29/2014] [Indexed: 05/04/2023]
Abstract
A review of mercury in the Canadian Arctic with a focus on field measurements is presented in part I (see Steffen et al., this issue). Here we provide insights into the dynamics of mercury in the Canadian Arctic from new and published mercury modeling studies using Environment Canada's mercury model. The model simulations presented in this study use global anthropogenic emissions of mercury for the period 1995-2005. The most recent modeling estimate of the net gain of mercury from the atmosphere to the Arctic Ocean is 75 Mg year(-1) and the net gain to the terrestrial ecosystems north of 66.5° is 42 Mg year(-1). Model based annual export of riverine mercury from North American, Russian and all Arctic watersheds to the Arctic Ocean are in the range of 2.8-5.6, 12.7-25.4 and 15.5-31.0 Mg year(-1), respectively. Analysis of long-range transport events of Hg at Alert and Little Fox Lake monitoring sites indicates that Asia contributes the most ambient Hg to the Canadian Arctic followed by contributions from North America, Russia, and Europe. The largest anthropogenic Hg deposition to the Canadian Arctic is from East Asia followed by Europe (and Russia), North America, and South Asia. An examination of temporal trends of Hg using the model suggests that changes in meteorology and changes in anthropogenic emissions equally contribute to the decrease in surface air elemental mercury concentrations in the Canadian Arctic with an overall decline of ~12% from 1990 to 2005. A slow increase in net deposition of Hg is found in the Canadian Arctic in response to changes in meteorology. Changes in snowpack and sea-ice characteristics and increase in precipitation in the Arctic related with climate change are found to be primary causes for the meteorology-related changes in air concentrations and deposition of Hg in the region. The model estimates that under the emissions reduction scenario of worldwide implementation of the best emission control technologies by 2020, mercury deposition could potentially be reduced by 18-20% in the Canadian Arctic.
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Affiliation(s)
- Ashu Dastoor
- Air Quality Research Division, Environment Canada, 2121 TransCanada Highway, Dorval, QC H9P 1J3, Canada.
| | - Andrew Ryzhkov
- Air Quality Research Division, Environment Canada, 2121 TransCanada Highway, Dorval, QC H9P 1J3, Canada
| | - Dorothy Durnford
- Meteorological Service of Canada, Environment Canada, 2121 TransCanada Highway, Dorval, QC H9P 1J3, Canada
| | - Igor Lehnherr
- University of Waterloo, Department of Earth and Environmental SciencesWaterloo, Ontario N2L 3G1, Canada
| | - Alexandra Steffen
- Environment Canada, Air Quality Research Division, Toronto, Ontario M3H 5T4, Canada
| | - Heather Morrison
- Environment Canada, Air Quality Research Division, Toronto, Ontario M3H 5T4, Canada
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Steffen A, Lehnherr I, Cole A, Ariya P, Dastoor A, Durnford D, Kirk J, Pilote M. Atmospheric mercury in the Canadian Arctic. Part I: a review of recent field measurements. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:3-15. [PMID: 25497576 DOI: 10.1016/j.scitotenv.2014.10.109] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/27/2014] [Accepted: 10/31/2014] [Indexed: 06/04/2023]
Abstract
Long-range atmospheric transport and deposition are important sources of mercury (Hg) to Arctic aquatic and terrestrial ecosystems. We review here recent progress made in the study of the transport, transformation, deposition and reemission of atmospheric Hg in the Canadian Arctic, focusing on field measurements (see Dastoor et al., this issue for a review of modeling studies on the same topics). Redox processes control the speciation of atmospheric Hg, and thus impart an important influence on Hg deposition, particularly during atmospheric mercury depletion events (AMDEs). Bromine radicals were identified as the primary oxidant of atmospheric Hg during AMDEs. Since the start of monitoring at Alert (NU) in 1995, the timing of peak AMDE occurrence has shifted to earlier times in the spring (from May to April) in recent years, and while AMDE frequency and GEM concentrations are correlated with local meteorological conditions, the reasons for this timing-shift are not understood. Mercury is subject to various post-depositional processes in snowpacks and a large portion of deposited oxidized Hg can be reemitted following photoreduction; how much Hg is deposited and reemitted depends on geographical location, meteorological, vegetative and sea-ice conditions, as well as snow chemistry. Halide anions in the snow can stabilize Hg, therefore it is expected that a smaller fraction of deposited Hg will be reemitted from coastal snowpacks. Atmospheric gaseous Hg concentrations have decreased in some parts of the Arctic (e.g., Alert) from 2000 to 2009 but at a rate that was less than that at lower latitudes. Despite numerous recent advances, a number of knowledge gaps remain, including uncertainties in the identification of oxidized Hg species in the air (and how this relates to dry vs. wet deposition), physical-chemical processes in air, snow and water-especially over sea ice-and the relationship between these processes and climate change.
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Affiliation(s)
- Alexandra Steffen
- Environment Canada, Air Quality Processes Research, Toronto M3H 5T4, Ontario, Canada.
| | - Igor Lehnherr
- University of Waterloo, Department of Earth and Environmental Sciences, Waterloo N2L 3G1, Ontario, Canada
| | - Amanda Cole
- Environment Canada, Air Quality Processes Research, Toronto M3H 5T4, Ontario, Canada
| | - Parisa Ariya
- McGill University, Department of Chemistry, 801 Sherbrooke St. W., Montreal H3A 2K6, Quebec, Canada; McGill University, Department of Atmospheric and Oceanic Sciences, 801 Sherbrooke St. W., Montreal H3A 2K6, Quebec, Canada
| | - Ashu Dastoor
- Environment Canada, National Prediction Development Division, Dorval H9P 1J3, Quebec, Canada
| | - Dorothy Durnford
- Environment Canada, National Prediction Development Division, Dorval H9P 1J3, Quebec, Canada
| | - Jane Kirk
- Environment Canada, Aquatic Contaminants Research Division, Burlington L7R 4A6, Ontario, Canada
| | - Martin Pilote
- Environment Canada, Aquatic Contaminants Research Division, Montreal H2Y 2E7, Quebec, Canada
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Gamberg M, Chételat J, Poulain AJ, Zdanowicz C, Zheng J. Mercury in the Canadian Arctic terrestrial environment: an update. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:28-40. [PMID: 24861531 DOI: 10.1016/j.scitotenv.2014.04.070] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/09/2014] [Accepted: 04/15/2014] [Indexed: 06/03/2023]
Abstract
Contaminants in the Canadian Arctic have been studied over the last twenty years under the guidance of the Northern Contaminants Program. This paper provides the current state of knowledge on mercury (Hg) in the Canadian Arctic terrestrial environment. Snow, ice, and soils on land are key reservoirs for atmospheric deposition and can become sources of Hg through the melting of terrestrial ice and snow and via soil erosion. In the Canadian Arctic, new data have been collected for snow and ice that provide more information on the net accumulation and storage of Hg in the cryosphere. Concentrations of total Hg (THg) in terrestrial snow are highly variable but on average, relatively low (<5 ng L(-1)), and methylmercury (MeHg) levels in terrestrial snow are also generally low (<0.1 ng L(-1)). On average, THg concentrations in snow on Canadian Arctic glaciers are much lower than those reported on terrestrial lowlands or sea ice. Hg in snow may be affected by photochemical exchanges with the atmosphere mediated by marine aerosols and halogens, and by post-depositional redistribution within the snow pack. Regional accumulation rates of THg in Canadian Arctic glaciers varied little during the past century but show evidence of an increasing north-to-south gradient. Temporal trends of THg in glacier cores indicate an abrupt increase in the early 1990 s, possibly due to volcanic emissions, followed by more stable, but relatively elevated levels. Little information is available on Hg concentrations and processes in Arctic soils. Terrestrial Arctic wildlife typically have low levels of THg (<5 μg g(-1) dry weight) in their tissues, although caribou (Rangifer tarandus) can have higher Hg because they consume large amounts of lichen. THg concentrations in the Yukon's Porcupine caribou herd vary among years but there has been no significant increase or decrease over the last two decades.
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Affiliation(s)
- Mary Gamberg
- Gamberg Consulting, Box 30130, Whitehorse, Yukon, Canada Y1A 5M2.
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Braune B, Chételat J, Amyot M, Brown T, Clayden M, Evans M, Fisk A, Gaden A, Girard C, Hare A, Kirk J, Lehnherr I, Letcher R, Loseto L, Macdonald R, Mann E, McMeans B, Muir D, O'Driscoll N, Poulain A, Reimer K, Stern G. Mercury in the marine environment of the Canadian Arctic: review of recent findings. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:67-90. [PMID: 24953756 DOI: 10.1016/j.scitotenv.2014.05.133] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 05/09/2014] [Accepted: 05/27/2014] [Indexed: 06/03/2023]
Abstract
This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine regions in the circumpolar Arctic. Mass balance models have been developed to provide quantitative estimates of THg fluxes into and out of the Arctic Ocean and Hudson Bay. Several recent studies on Hg biomagnification have improved our understanding of trophic transfer of Hg through marine food webs. Over the past several decades, Hg concentrations have increased in some marine biota, while other populations showed no temporal change. Marine biota also exhibited considerable geographic variation in Hg concentrations with ringed seals, beluga and polar bears from the Beaufort Sea region having higher Hg concentrations compared with other parts of the Canadian Arctic. The drivers of these variable patterns of Hg bioaccumulation, both regionally and temporally, within the Canadian Arctic remain unclear. Further research is needed to identify the underlying processes including the interplay between biogeochemical and food web processes and climate change.
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Affiliation(s)
- Birgit Braune
- Environment Canada, National Wildlife Research Centre, Carleton University, Raven Road, Ottawa, Ontario, Canada K1A 0H3.
| | - John Chételat
- Environment Canada, National Wildlife Research Centre, Carleton University, Raven Road, Ottawa, Ontario, Canada K1A 0H3
| | - Marc Amyot
- Département de sciences biologiques, Université de Montréal, CP 6128, Succ. Centre-Ville Pavillon Marie-Victorin, Montreal, Quebec, Canada H3C 3 J7
| | - Tanya Brown
- Fisheries and Oceans Canada, Institute of Ocean Sciences, 9860 West Saanich Road, PO Box 6000, Sidney, British Columbia, Canada V8L 4B2; Royal Military College of Canada, PO Box 17000, Station Forces, Kingston, Ontario, Canada K7K 7B4
| | - Meredith Clayden
- Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick, Canada E2L 4L5
| | - Marlene Evans
- Environment Canada, National Water Research Institute, 11 Innovation Blvd., Saskatoon, Saskatchewan, Canada S7N 3H5
| | - Aaron Fisk
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario, Canada N9B 3P4
| | - Ashley Gaden
- Centre for Earth Observation Science, 497 Wallace Bldg., University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Catherine Girard
- Département de sciences biologiques, Université de Montréal, CP 6128, Succ. Centre-Ville Pavillon Marie-Victorin, Montreal, Quebec, Canada H3C 3 J7
| | - Alex Hare
- Centre for Earth Observation Science, 497 Wallace Bldg., University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Jane Kirk
- Environment Canada, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6
| | - Igor Lehnherr
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
| | - Robert Letcher
- Environment Canada, National Wildlife Research Centre, Carleton University, Raven Road, Ottawa, Ontario, Canada K1A 0H3
| | - Lisa Loseto
- Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6
| | - Robie Macdonald
- Fisheries and Oceans Canada, Institute of Ocean Sciences, 9860 West Saanich Road, PO Box 6000, Sidney, British Columbia, Canada V8L 4B2
| | - Erin Mann
- Department of Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6
| | - Bailey McMeans
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario, Canada N9B 3P4
| | - Derek Muir
- Environment Canada, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6
| | - Nelson O'Driscoll
- Department of Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6
| | - Alexandre Poulain
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5
| | - Ken Reimer
- Royal Military College of Canada, PO Box 17000, Station Forces, Kingston, Ontario, Canada K7K 7B4
| | - Gary Stern
- Centre for Earth Observation Science, 497 Wallace Bldg., University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2; Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6
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Mann EA, Mallory ML, Ziegler SE, Tordon R, O'Driscoll NJ. Mercury in Arctic snow: quantifying the kinetics of photochemical oxidation and reduction. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:115-132. [PMID: 25097105 DOI: 10.1016/j.scitotenv.2014.07.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 06/27/2014] [Accepted: 07/07/2014] [Indexed: 06/03/2023]
Abstract
Controlled experiments were performed with frozen and melted Arctic snow to quantify relationships between mercury photoreaction kinetics, ultra violet (UV) radiation intensity, and snow ion concentrations. Frozen (-10°C) and melted (4°C) snow samples from three Arctic sites were exposed to UV (280-400 nm) radiation (1.26-5.78 W · m(-2)), and a parabolic relationship was found between reduction rate constants in frozen and melted snow with increasing UV intensity. Total photoreduced mercury in frozen and melted snow increased linearly with greater UV intensity. Snow with the highest concentrations of chloride and iron had larger photoreduction and photooxidation rate constants, while also having the lowest Hg(0) production. Our results indicate that the amount of mercury photoreduction (loss from snow) is the highest at high UV radiation intensities, while the fastest rates of mercury photoreduction occurred at both low and high intensities. This suggests that, assuming all else is equal, earlier Arctic snow melt periods (when UV intensities are less intense) may result in less mercury loss to the atmosphere by photoreduction and flux, since less Hg(0) is photoproduced at lower UV intensities, thereby resulting in potentially greater mercury transport to aquatic systems with snowmelt.
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Affiliation(s)
- E A Mann
- Department of Environmental Science, Acadia University, Wolfville, NS, Canada; Environmental Science Programme, Memorial University of Newfoundland, St. John's, NL, Canada
| | - M L Mallory
- Department of Biology, Acadia University, Wolfville, NS, Canada
| | - S E Ziegler
- Environmental Science Programme, Memorial University of Newfoundland, St. John's, NL, Canada
| | - R Tordon
- Environment Canada, Dartmouth, NS, Canada
| | - N J O'Driscoll
- Department of Environmental Science, Acadia University, Wolfville, NS, Canada.
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Baya PA, Gosselin M, Lehnherr I, St Louis VL, Hintelmann H. Determination of monomethylmercury and dimethylmercury in the Arctic marine boundary layer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:223-232. [PMID: 25437177 DOI: 10.1021/es502601z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Our understanding of the biogeochemical cycling of monomethylmercury (MMHg) in the Arctic is incomplete because atmospheric sources and sinks of MMHg are still unclear. We sampled air in the Canadian Arctic marine boundary layer to quantify, for the first time, atmospheric concentrations of methylated Hg species (both MMHg and dimethylmercury (DMHg)), and, estimate the importance of atmospheric deposition as a source of MMHg to Arctic land- and sea-scapes. Overall atmospheric MMHg and DMHg concentrations (mean ± SD) were 2.9 ± 3.6 and 3.8 ± 3.1 (n = 37) pg m(-3), respectively. Concentrations of methylated Hg species in the marine boundary layer varied significantly among our sites, with a predominance of MMHg over Hudson Bay (HB), and DMHg over Canadian Arctic Archipelago (CAA) waters. We concluded that DMHg is of marine origin and that primary production rate and sea-ice cover are major drivers of its concentration in the Canadian Arctic marine boundary layer. Summer wet deposition rates of atmospheric MMHg, likely to be the product of DMHg degradation in the atmosphere, were estimated at 188 ± 117.5 ng m(-2) and 37 ± 21.7 ng m(-2) for HB and CAA, respectively, sustaining MMHg concentrations available for biomagnification in the pelagic food web.
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Affiliation(s)
- Pascale A Baya
- Environmental & Life Sciences Graduate Program, Trent University , 1600 West Bank Drive, Peterborough, Ontario, K9J 7B8, Canada
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Chai X, Hao Y, Li Z, Zhu W, Zhao W. The dependence of the methylation of mercury on the landfill stabilization process and implications for the landfill management. CHEMOSPHERE 2015; 119:828-834. [PMID: 25218981 DOI: 10.1016/j.chemosphere.2014.08.004] [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: 12/28/2013] [Revised: 07/30/2014] [Accepted: 08/01/2014] [Indexed: 06/03/2023]
Abstract
Mercury species and other chemical characteristics of the leachate from anaerobic and semi-aerobic landfills were analyzed to investigate the factors that control mercury methylation during the landfill stabilization process. At the early landfill stage, the total mercury (THg) and the monomethyl mercury (MMHg) released rapidly and significantly, the THg concentration of the semi-aerobic landfill leachate was obviously higher than that of the anaerobic landfill leachate, while compared with the semi-aerobic landfill, the MMHg concentration in the anaerobic landfill was higher. As the landfill time increased, both of THg and MMHg concentration decreased quickly, the THg concentration in the anaerobic landfill was much higher than that in semi-aerobic landfill, while the MMHg concentration in the anaerobic landfill was lower than that in the semi-aerobic landfill. Generally, the concentrations of dimethyl mercury (DMHg) in the anaerobic landfill leachate were slightly higher than in the semi-aerobic landfill leachate during the stabilization process. A significant positive correlation was found between the DMHg concentrations and the pH value in anaerobic landfill leachate, but this correlation was opposite in the semi-aerobic landfill. The oxidative-reductive potential (ORP) condition was found to be the controlling factor of the methylation process during the early stage. However, the chemical characteristics, especially the TOC concentration, appeared to be the dominant factor affecting the methylation process as the landfill time increased.
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Affiliation(s)
- Xiaoli Chai
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
| | - Yongxia Hao
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; Shanghai Environmental Sanitation Engineering Design Institute, Shanghai 200232, China
| | - Zhonggen Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
| | - Wei Zhu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
| | - Wentao Zhao
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.
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Beattie SA, Armstrong D, Chaulk A, Comte J, Gosselin M, Wang F. Total and methylated mercury in Arctic multiyear sea ice. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:5575-5582. [PMID: 24766483 DOI: 10.1021/es5008033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Mercury is one of the primary contaminants of concern in the Arctic marine ecosystem. While considerable efforts have been directed toward understanding mercury cycling in the Arctic, little is known about mercury dynamics within Arctic multiyear sea ice, which is being rapidly replaced with first-year ice. Here we report the first study on the distribution and potential methylation of mercury in Arctic multiyear sea ice. Based on three multiyear ice cores taken from the eastern Beaufort Sea and McClure Strait, total mercury concentrations ranged from 0.65 to 60.8 pM in bulk ice, with the highest values occurring in the topmost layer (∼40 cm) which is attributed to the dynamics of particulate matter. Methylated mercury concentrations ranged from below the method detection limit (<0.1 pM) to as high as 2.64 pM. The ratio of methylated to total mercury peaked, up to ∼40%, in the mid to bottom sections of the ice, suggesting the potential occurrence of in situ mercury methylation. The annual fluxes of total and methylated mercury into the Arctic Ocean via melt of multiyear ice are estimated to be 420 and 42 kg yr(-1), respectively, representing an important and changing source of mercury and methylmercury into the Arctic Ocean marine ecosystem.
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Affiliation(s)
- Sarah A Beattie
- Center for Earth Observation Science, Department of Environment and Geography, University of Manitoba , Winnipeg, MB R3T 2N2, Canada
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St Pierre KA, Chétélat J, Yumvihoze E, Poulain AJ. Temperature and the sulfur cycle control monomethylmercury cycling in high Arctic coastal marine sediments from Allen Bay, Nunavut, Canada. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:2680-2687. [PMID: 24555761 DOI: 10.1021/es405253g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Monomethylmercury (MMHg) is a neurotoxin of concern in the Canadian Arctic due to its tendency to bioaccumulate and the importance of fish and wildlife in the Inuit diet. In lakes and wetlands, microbial sediment communities are integral to the cycling of MMHg; however, the role of Arctic marine sediments is poorly understood. With projected warming, the effect of temperature on the production and degradation of MMHg in Arctic environments also remains unclear. We examined MMHg dynamics across a temperature gradient (4, 12, 24 °C) in marine sediments collected in Allen Bay, Nunavut. Slurries were spiked with stable mercury isotopes and amended with specific microbial stimulants and inhibitors, and subsampled over 12 days. Maximal methylation and demethylation potentials were low, ranging from below detection to 1.13 pmol g(-1) h(-1) and 0.02 pmol g(-1) h(-1), respectively, suggesting that sediments are likely not an important source of MMHg to overlying water. Our results suggest that warming may result in an increase in Hg methylation - controlled by temperature-dependent sulfate reduction, without a compensatory increase in demethylation. This study highlights the need for further research into the role of high Arctic marine sediments and climate on the Arctic marine MMHg budget.
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Affiliation(s)
- K A St Pierre
- Department of Biology, University of Ottawa , 30 Marie-Curie, Ottawa, Ontario, K1N 6N5, Canada
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Dastoor AP, Durnford DA. Arctic Ocean: is it a sink or a source of atmospheric mercury? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:1707-1717. [PMID: 24328426 DOI: 10.1021/es404473e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
High levels of mercury in marine mammals threaten the health of Arctic inhabitants. Whether the Arctic Ocean (AO) is a sink or a source of atmospheric mercury is unknown. Given the paucity of observations in the Arctic, models are useful in addressing this question. GEOS-Chem and GRAHM, two complex numerical mercury models, present contrasting pictures of atmospheric mercury input to AO at 45 and 108 Mg yr(-1), respectively, and ocean evasion at 90 and 33 Mg yr(-1), respectively. We provide a comprehensive evaluation of GRAHM simulated atmospheric mercury input to AO using mercury observations in air, precipitation and snowpacks, and an analysis of the discrepancy between the two modeling estimates using observations. We discover two peaks in high-latitude summertime concentrations of atmospheric mercury. We show that the first is caused mainly by snowmelt revolatilization and the second by AO evasion of mercury. Riverine mercury export to AO is estimated at 50 Mg yr(-1) based on measured DOC export and at 15.5-31 Mg yr(-1) based on simulated mercury in meltwater. The range of simulated mercury fluxes to and from AO reflects uncertainties in modeling mercury in the Arctic; comprehensive observations in all compartments of the Arctic ecosystem are needed to close the gap.
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Affiliation(s)
- Ashu P Dastoor
- Air Quality Research Division, Environment Canada , 2121 TransCanada Highway, Dorval, Quebec H9P 1J3, Canada
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Fu X, Feng X, Yin R, Zhang H. Diurnal variations of total mercury, reactive mercury, and dissolved gaseous mercury concentrations and water/air mercury flux in warm and cold seasons from freshwaters of southwestern China. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:2256-2265. [PMID: 23832677 DOI: 10.1002/etc.2323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/10/2013] [Accepted: 06/22/2013] [Indexed: 06/02/2023]
Abstract
Diurnal variations of water total Hg, reactive Hg, and dissolved gaseous Hg concentrations and mercury flux were monitored at 2 sites in warm and cold seasons in an alkaline reservoir in southwestern China. Concentrations of total Hg and reactive Hg, as well as Hg fluxes, usually exhibited a consistent diurnal trend, with elevated values observed during the day. The increasing reactive Hg concentrations and Hg fluxes were highly related to the incident intensity of solar radiation, suggesting that sunlight-induced processes played an important role in the transformation of Hg in the study area. Dissolved gaseous Hg concentrations experienced different diurnal variations among the sampling sites, with peak dissolved gaseous Hg at midday under sunny weather conditions and in the early morning under cloudy and/or partially cloudy weather conditions. The peak values of dissolved gaseous Hg observed at midday agree well with previous results and highlight the sunlight-induced production of dissolved gaseous Hg in freshwaters, whereas dissolved gaseous Hg peaks at night suggest that microbial activity might be an additional mechanism for dissolved gaseous Hg production in surface waters. Total Hg, reactive Hg, and dissolved gaseous Hg concentrations and Hg fluxes in the warm season were consistently higher than those in the cold season; this is probably attributable to the combined effect of seasonal variations of environmental parameters, transformation of Hg species, and microbial activities.
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Affiliation(s)
- Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, People’s Republic of China
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Evaluation and optimization of solid adsorbents for the sampling of gaseous methylated mercury species. Anal Chim Acta 2013; 786:61-9. [DOI: 10.1016/j.aca.2013.05.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/03/2013] [Accepted: 05/05/2013] [Indexed: 11/23/2022]
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van der Velden S, Dempson JB, Evans MS, Muir DCG, Power M. Basal mercury concentrations and biomagnification rates in freshwater and marine food webs: effects on Arctic charr (Salvelinus alpinus) from eastern Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 444:531-542. [PMID: 23295180 DOI: 10.1016/j.scitotenv.2012.11.099] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/27/2012] [Accepted: 11/28/2012] [Indexed: 06/01/2023]
Abstract
Patterns of total Hg (THg) and methyl Hg (MeHg) biomagnification were investigated in six pairs of co-located lacustrine and marine food webs supporting a common predator, Arctic charr. Mercury biomagnification rates (the slope of log Hg concentration versus δ(15)N-inferred trophic level) did not differ significantly between the two feeding habitats for either THg or MeHg, but THg and MeHg concentrations at the base of the food web were higher in the lacustrine environment than in the marine environment. The proportion of THg as MeHg was related to trophic level, and the relationship was statistically similar in the lacustrine and marine habitats. The biomagnification rate of MeHg exceeded that of THg in both habitats. We conclude that the known difference in Hg concentration between anadromous and non-anadromous Arctic charr is driven by differential Hg concentrations at the base of the lacustrine and marine foodwebs, and not by differential biomagnification rates.
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Affiliation(s)
- S van der Velden
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
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36
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Wang F, Macdonald RW, Armstrong DA, Stern GA. Total and methylated mercury in the Beaufort Sea: the role of local and recent organic remineralization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:11821-8. [PMID: 23025753 DOI: 10.1021/es302882d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Mercury is a major contaminant in the Arctic marine ecosystem. While extensive studies have been conducted on mercury in the Arctic's atmosphere and biota, far less is known about the distribution and dynamics of mercury species in the Arctic Ocean. Here, we present vertical profiles for total mercury (Hg(T)) and total methylated mercury (MeHg(T), sum of monomethylmercury and dimethylmercury) from the Beaufort Sea of the Arctic Ocean at locations with differing sea ice conditions. The concentration of Hg(T) ranged from 0.40 to 2.9 pM, with a surface enrichment that can be attributed to a combination of sea ice-modified atmospheric deposition and riverine input. The concentration of MeHg(T) ranged from <0.04 to 0.59 pM, with a subsurface peak occurring at the same depth as a nutrient maximum with lower dissolved oxygen, which is consistent with the recent findings in the Pacific Ocean, Southern Ocean, and Mediterranean Sea. However, unlike the interior ocean regions, the nutrient maximum in the Beaufort Sea is predominantly an advective feature produced over the Chukchi Shelf. On the basis of the short lifetime of monomethylmercury in seawater, we propose that the MeHg(T) profile in the Beaufort Sea reflects the local, short-term remineralization of labile organic matter, and not the larger signal of organic remineralization advected from the Chukchi Sea in the halocline. The finding that MeHg(T) is produced locally, reflecting recent strength of organic matter cycling, not only explains wide variance in MeHg(T) in seawater and biota over time and space, but also implies that MeHg(T) could be used as an indicator of the recent export flux of labile organic matter.
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Affiliation(s)
- Feiyue Wang
- Center for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg, MB, Canada R3T 2N2.
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37
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Kirk JL, Lehnherr I, Andersson M, Braune BM, Chan L, Dastoor AP, Durnford D, Gleason AL, Loseto LL, Steffen A, St Louis VL. Mercury in Arctic marine ecosystems: sources, pathways and exposure. ENVIRONMENTAL RESEARCH 2012; 119:64-87. [PMID: 23102902 PMCID: PMC4142812 DOI: 10.1016/j.envres.2012.08.012] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 08/02/2012] [Accepted: 08/13/2012] [Indexed: 05/20/2023]
Abstract
Mercury in the Arctic is an important environmental and human health issue. The reliance of Northern Peoples on traditional foods, such as marine mammals, for subsistence means that they are particularly at risk from mercury exposure. The cycling of mercury in Arctic marine systems is reviewed here, with emphasis placed on the key sources, pathways and processes which regulate mercury levels in marine food webs and ultimately the exposure of human populations to this contaminant. While many knowledge gaps exist limiting our ability to make strong conclusions, it appears that the long-range transport of mercury from Asian emissions is an important source of atmospheric Hg to the Arctic and that mercury methylation resulting in monomethylmercury production (an organic form of mercury which is both toxic and bioaccumulated) in Arctic marine waters is the principal source of mercury incorporated into food webs. Mercury concentrations in biological organisms have increased since the onset of the industrial age and are controlled by a combination of abiotic factors (e.g., monomethylmercury supply), food web dynamics and structure, and animal behavior (e.g., habitat selection and feeding behavior). Finally, although some Northern Peoples have high mercury concentrations of mercury in their blood and hair, harvesting and consuming traditional foods have many nutritional, social, cultural and physical health benefits which must be considered in risk management and communication.
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Affiliation(s)
- Jane L Kirk
- Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Dr, Burlington, ON L7R 4A6, Canada.
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van der Velden S, Reist JD, Babaluk JA, Power M. Biological and life-history factors affecting total mercury concentrations in Arctic charr from Heintzelman Lake, Ellesmere Island, Nunavut. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 433:309-317. [PMID: 22809730 DOI: 10.1016/j.scitotenv.2012.06.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 06/13/2012] [Accepted: 06/14/2012] [Indexed: 06/01/2023]
Abstract
A snapshot sample of Arctic charr (Salvelinus alpinus) from Heintzelman Lake (81°42'N, 66°56'W), Ellesmere Island, Canada was used to elucidate the biological and life-history factors potentially influencing individual total mercury (THg) concentrations. Migratory history was significant, with anadromous fish having a lower mean THg concentration (64 μg/kg ww) than the non-anadromous Arctic charr (117 μg/kg ww). The increase in individual THg concentration with age was shown to be independent of length-at-age when large and small individuals within the same age groups were compared. Similarly, the diets of individual Arctic charr were comparable regardless of size, and there was no apparent ontogenetic shift in diet that could explain differences in length-at-age or THg concentration among fast- and slow-growing groups of fish (i.e., fish of the same age but differing sizes). Maturity state was also not related to THg concentration, but appears to be related to differences in length-at-age, with slow-growing fish allocating more energy to reproduction than fast-growing conspecifics. The differences in THg concentration among individual Arctic charr were best explained by fish age. We suggest that the increase in mercury concentration with age can be altered by a shift in diet (e.g., to piscivory) or habitat (e.g., anadromy), but is otherwise unaffected by changes in size or length-at-age.
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Fu X, Feng X, Sommar J, Wang S. A review of studies on atmospheric mercury in China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 421-422:73-81. [PMID: 22134034 DOI: 10.1016/j.scitotenv.2011.09.089] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 05/31/2023]
Abstract
Due to the fast developing economy, mercury (Hg) emissions to the atmosphere from Chinese mainland have increased rapidly in recent years. Consequently, this issue has received a considerable attention internationally. This paper reviews the current understanding of and knowledge on atmospheric Hg emissions, distribution and transport in China. The magnitude of Hg emissions to the atmosphere from Chinese anthropogenic sources has been estimated to be in the range of 500-700 tons per year, whereby comprising a significant proportion of the globe total anthropogenic emissions. Emissions of Hg from natural surfaces including bare soil, water, and vegetation covered soil tend in a comparison to be higher in China than in Europe and North America, indicating the importance of this source category. Atmospheric Hg exhibits a significant concentration variability among urban, semi-remote, and remote areas. Total Gaseous Mercury (TGM) concentrations in urban areas of China were often 1.5 - 5 folds higher compared to the corresponding settings in North America and Europe. In turn, particulate mercury (PHg) concentrations in urban areas of China were up to two orders of magnitude higher compared to North America and Europe. Atmospheric observations made at strictly remote sites in China also include the presence of occasional high concentrations of TGM, and the more short-lived fractions PHg and Reactive Gaseous Mercury (RGM). Accordingly, Hg deposition fluxes tended to be higher in China, with remote areas and urban areas being 1-2 times and 1-2 magnitude higher than those in North America and Europe, respectively.
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Affiliation(s)
- Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
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Dove A, Hill B, Klawunn P, Waltho J, Backus S, McCrea RC. Spatial distribution and trends of total mercury in waters of the Great Lakes and connecting channels using an improved sampling technique. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2012; 161:328-334. [PMID: 21715070 DOI: 10.1016/j.envpol.2011.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 06/03/2011] [Indexed: 05/31/2023]
Abstract
Environment Canada recently developed a clean method suitable for sampling trace levels of metals in surface waters. The results of sampling for total mercury in the Laurentian Great Lakes between 2003 and 2009 give a unique basin-wide perspective of concentrations of this important contaminant and represent improved knowledge of mercury in the region. Results indicate that concentrations of total mercury in the offshore regions of the lakes were within a relatively narrow range from about 0.3 to 0.8 ng/L. The highest concentrations were observed in the western basin of Lake Erie and concentrations then declined towards the east. Compared to the offshore, higher levels were observed at some nearshore locations, particularly in lakes Erie and Ontario. The longer-term temporal record of mercury in Niagara River suspended sediments indicates an approximate 30% decrease in equivalent water concentrations since 1986.
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Affiliation(s)
- A Dove
- Water Quality Monitoring & Surveillance, Environment Canada, 867 Lakeshore Road, Burlington, ON L7R 4A6, Canada.
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Marusczak N, Larose C, Dommergue A, Yumvihoze E, Lean D, Nedjai R, Ferrari C. Total mercury and methylmercury in high altitude surface snow from the French Alps. THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 409:3949-3954. [PMID: 21752427 DOI: 10.1016/j.scitotenv.2011.06.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 06/11/2011] [Accepted: 06/16/2011] [Indexed: 05/31/2023]
Abstract
Surface snow samples were collected weekly from the 31st of December 2008 to the 21st of June 2009 from Lake Bramant in the French Alps. Total mercury (THg), total dissolved mercury (THgD), methylmercury (MeHg) and particle distributions in surface snow were analyzed. Results showed that THg concentrations, MeHg concentrations and particle load increased with snow surface temperature, which is an indicator of rising temperatures as the season progresses. Significant correlations between MeHg and snow surface temperature and MeHg and total particles greater than 10 μm were observed. This suggests that the MeHg found in the snow originates from atmospheric deposition processes rather than in situ snowpack sources. This study suggests that an important post-winter atmospheric deposition of MeHg and THg occurs on summital zones of the French Alps and it is likely that this contamination originates from the surrounding valleys.
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Affiliation(s)
- Nicolas Marusczak
- Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) CNRS UMR 5183, 54, rue Molière, Domaine Universitaire, B.P. 96, 38402 Saint Martin d'Hères, France
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Durnford D, Dastoor A. The behavior of mercury in the cryosphere: A review of what we know from observations. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jd014809] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Black FJ, Conaway CH, Flegal AR. Stability of dimethyl mercury in seawater and its conversion to monomethyl mercury. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:4056-4062. [PMID: 19569330 DOI: 10.1021/es9001218] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dimethyl mercury (DMHg) is commonly detected in the world's oceans, but little is known about the mechanisms responsible for DMHg degradation in natural waters or the products of this degradation. Similarly, the potential for the conversion of DMHg to monomethyl mercury (MMHg) under the acidic conditions commonly used to preserve samples for MMHg analysis has not been fully addressed. We provide evidence suggesting that DMHg in natural seawater is not readily photodegraded by sunlight as previously thought. Other experiments demonstrated that DMHg in seawater is, however, readily decomposed under acidic conditions, with MMHg as the predominant product. This facile conversion of DMHg to MMHg at low pH both necessitates an alternative preservation method to acidification for samples to be analyzed for MMHg when DMHg is present, and requires that data from previous studies of MMHg in seawater employing sample acidification be revisited in instances where appreciable DMHg concentrations were possible.
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Affiliation(s)
- Frank J Black
- WIGS Laboratory, Department of Environmental Toxicology, University of California, Santa Cruz, California 95064, USA.
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Kirk JL, St Louis VL. Multiyear total and methyl mercury exports from two major sub-Arctic rivers draining into Hudson Bay, Canada. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:2254-2261. [PMID: 19452871 DOI: 10.1021/es803138z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
From 2003 to 2007, concentrations of total mercury and methylmercury (THg and MeHg) were continuously measured in two Canadian sub-Arctic rivers (the Nelson and the Churchill) that drain into western Hudson Bay. THg and MeHg concentrations were low in the Nelson River (mean i standard deviation, 0.88 +/- 0.33 and 0.05 +/- 0.03 ng L(-1), respectively). The Churchill River, however, had high concentrations of Hg, particularly MeHg (1.96 +/- 0.8 and 0.18 +/- 0.09 ng L(-1), respectively) and hence may be an important source of MeHg to organisms feeding in the Churchill River estuary. A large portion of THg in the Nelson River was particulate-bound (39 +/- 23%), while in the Churchill River, most was in the dissolved form (78 +/- 15%) and is likely dissolved organic carbon (DC)-bound Hg originating in the surrounding wetlands. In fact, both the Nelson and Churchill Rivers had high DOC concentrations and were therefore large exporters of DOC to Hudson Bay (1480 +/- 723 and 392 +/- 309 x 10(3) t year(-1), respectively) compared to rivers to the south and east Despite high Churchill River Hg concentrations, due to large Nelson River flows, average THg and MeHg exports to Hudson Bay from the Churchill River (37 +/- 28 and 4 +/- 4 kg year(-1), respectively) were about one-third and half the Nelson River exports (113 +/- 52 and 9 +/- 4 kg year(-1)). Interestingly, combined Hg exports to Hudson Bay from Nelson and Churchill River discharge are comparable to THg inputs from Hudson Bay springtime snowmelt (177 +/-140 kg year(-1)) but are approximately 13 times greater than MeHg snowmelt inputs (1 +/- 1 kg year(-1)). Although Hg inputs from rivers and snowmelt together may account for a large portion of the THg pool in Hudson Bay, these inputs account for a lesser portion of the MeHg pool, thus highlighting the importance of water column Hg(ll) methylation as a source of MeHg to Hudson Bay marine food webs.
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Affiliation(s)
- Jane L Kirk
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
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Conaway CH, Black FJ, Gault-Ringold M, Pennington JT, Chavez FP, Flegal AR. Dimethylmercury in coastal upwelling waters, Monterey Bay, California. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:1305-1309. [PMID: 19350895 DOI: 10.1021/es802705t] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Depth profiles of dimethylmercury (DMHg) concentration were determined at nearshore to offshore sites in Monterey Bay, California. The onset of spring upwelling in the bay was accompanied by increases in DMHg concentrations. Profiles show DMHg increasing gradually with depth in fall and winter from <0.03 pM at the surface to 0.5 pM at 200 m. During the spring, DMHg concentrations increased between 30 and 100 m, first within Monterey Bay, then offshore. This change was accompanied by an increase in DMHg concentrations in the surface water DMHg between fall/winter (<0.03 pM) and spring (0.06-0.29 pM). Microbial activity associated with the remineralization of sinking organic matter produced by the high primary production in the bay may result in the relatively high DMHg in subsurface water in the bay, which when upwelled may facilitate the incorporation of organomercury into biota. As a result, productive coastal upwelling areas may represent an important source of methylated mercury to surface waters, and thus be an important source of mercury to marine ecosystems.
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Affiliation(s)
- Christopher H Conaway
- Department of Microbiology and Environmental Toxicology, University of California at Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA.
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Oiffer L, Siciliano SD. Methyl mercury production and loss in Arctic soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 407:1691-700. [PMID: 19081608 DOI: 10.1016/j.scitotenv.2008.10.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 10/09/2008] [Accepted: 10/12/2008] [Indexed: 05/16/2023]
Abstract
Mercury has been found in polar bears and other top predators in the Arctic at concentrations that pose a risk to the indigenous population, however, the means by which this occurs is uncertain. There has been extensive research on the atmospheric cycling of mercury but little is known about mercury cycling in Arctic terrestrial ecosystems. The objective of this study was to determine whether wet sedge meadow soils within the Truelove Lowlands, Devon Island, NT, Canada (75 degrees 33'N, 84 degrees 40'N) were acting as sources or sinks for methylmercury (MeHg). Over the course of an Arctic summer, MeHg concentrations and other biophysical characteristics were measured at four wet sedge meadows over a 19 day study period that commenced approximately 1 month after snowmelt. Soil MeHg concentrations declined during the study period, indicating a net loss of MeHg over the summer. The dominant ligand in solution appeared to be dissolved organic matter, little sulfide was detected, and it would seem that most of the mercury was unavailable for methylation during the summer sampling period. In soil microcosms, spiked with 5.0 nmol g(-1) (1 microg g(-1)) HgCl2, the soil did methylate mercury suggesting that there is the potential for mercury methylation. We also noted significant spatial variability in MeHg concentrations between catenas that could not be explained by other biophysical parameters, which are known to affect methylation. Given our data and previous geochemical data collected from suprapermafrost groundwater during snowmelt, it seems likely that methylation may occur during the spring melt period in the arctic. Furthermore the geochemical variability of the melt water may lead to the spatial variability observed in MeHg concentrations in this study.
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Affiliation(s)
- Lindsay Oiffer
- Department of Soil Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan S7N 5A8, Canada
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Kirk JL, St Louis VL, Hintelmann H, Lehnherr I, Else B, Poissant L. Methylated mercury species in marine waters of the Canadian high and sub Arctic. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8367-8373. [PMID: 19068819 DOI: 10.1021/es801635m] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dimethyl Hg (DMHg) was examined in marine waters of the Canadian Arctic Archipelago (CAA), Hudson Strait, and Hudson Bay. Concentrations of THg were low throughout the water column in all regions sampled (mean +/- standard deviation; 0.40 +/- 0.47 ng L(-1)). Concentrations of MMHg were also generally low atthe surface (23.8 +/- 9.9 pg L(-1)); however at mid- and bottom depths, MMHg was present at concentrations sufficient to initiate bioaccumulation of MMHg through Arctic marine foodwebs (maximum 178 pg L(-1); 70.3 +/- 37.3 pg L(-1)). In addition, at mid- and bottom depths, the % of THg that was MMHg was high (maximum 66%; 28 +/- 16%), suggesting that active methylation of inorganic Hg(II) occurs in deep Arctic marine waters. Interestingly, there was a constant, near 1:1, ratio between concentrations of MMHg and DMHg at all sites and depths, suggesting that methylated Hg species are in equilibrium with each other and/or are produced by similar processes throughout the water column. Our results also demonstrate that oceanographic processes, such as water regeneration and vertical mixing, affect Hg distribution in marine waters. Vertical mixing, for example, likely transported MMHg and DMHg upward from production zones at some sites, resulting in elevated concentrations of these species in surface waters (up to 68.0 pg L(-1)) where primary production and thus uptake of MMHg by biota is potentially highest. Finally, calculated instantaneous ocean-atmosphere fluxes of gaseous Hg species demonstrated that Arctic marine waters are a substantial source of DMHg and GEM to the atmosphere (27.3 +/- 47.8 and 130 +/- 138 ng m(-2) day(-1), respectively) during the ice-free season.
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Affiliation(s)
- Jane L Kirk
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9,
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Poissant L, Zhang HH, Canário J, Constant P. Critical review of mercury fates and contamination in the Arctic tundra ecosystem. THE SCIENCE OF THE TOTAL ENVIRONMENT 2008; 400:173-211. [PMID: 18707754 DOI: 10.1016/j.scitotenv.2008.06.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 06/27/2008] [Accepted: 06/27/2008] [Indexed: 05/26/2023]
Abstract
Mercury (Hg) contamination in tundra region has raised substantial concerns, especially since the first report of atmospheric mercury depletion events (AMDEs) in the Polar Regions. During the past decade, steady progress has been made in the research of Hg cycling in the Polar Regions. This has generated a unique opportunity to survey the whole Arctic in respect to Hg issue and to find out new discoveries. However, there are still considerable knowledge gaps and debates on the fate of Hg in the Arctic and Antarctica, especially regarding the importance and significance of AMDEs vs. net Hg loadings and other processes that burden Hg in the Arctic. Some studies argued that climate warming since the last century has exerted profound effects on the limnology of High Arctic lakes, including substantial increases in autochthonous primary productivity which increased in sedimentary Hg, whereas some others pointed out the importance of the formation and postdeposition crystallographic history of the snow and ice crystals in determining the fate and concentration of mercury in the cryosphere in addition to AMDEs. Is mercury re-emitted back to the atmosphere after AMDEs? Is Hg methylation effective in the Arctic tundra? Where the sources of MeHg are? What is its fate? Is this stimulated by human made? This paper presents a critical review about the fate of Hg in the Arctic tundra, such as pathways and process of Hg delivery into the Arctic ecosystem; Hg concentrations in freshwater and marine ecosystems; Hg concentrations in terrestrial biota; trophic transfer of Hg and bioaccumulation of Hg through food chain. This critical review of mercury fates and contamination in the Arctic tundra ecosystem is assessing the impacts and potential risks of Hg contamination on the health of Arctic people and the global northern environment by highlighting and "perspectiving" the various mercury processes and concentrations found in the Arctic tundra.
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Affiliation(s)
- Laurier Poissant
- Environment Canada, Science and Technology branch Montréal, Québec, Canada.
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O'Driscoll NJ, Poissant L, Canário J, Lean DRS. Dissolved gaseous mercury concentrations and mercury volatilization in a frozen freshwater fluvial lake. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:5125-5130. [PMID: 18754358 DOI: 10.1021/es800216q] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In situ mesocosm experiments were performed to examine dissolved gaseous mercury (DGM), mercury volatilization, and sediment interactions in a frozen freshwater fluvial lake (Lake St. Louis, Beauharnois, QC). Two large in situ mesocosm cylinders, one open-bottomed and one close-bottomed (no sediment diffusion), were used to isolate the water column and minimize advection. Mercury volatilization over the closed-bottom mesocosm did not display a diurnal pattern and was low (mean = -0.02 ng m(-2) h(-1), SD = 0.28, n=71). Mercury volatilization over the open-bottom mesocosm was also low (mean = 0.24 ng m(-2) h(-1), SD = 0.08, n=96) however a diurnal pattern was observed. Low and constant concentrations of DGM were observed in surface water in both the open-bottomed and close-bottomed mesocosms (combined mean = 27.6 pg L(-1), SD = 7.2, n=26). Mercury volatilization was significantly correlated with solar radiation in both the close-bottomed (Pearson correlation = 0.33, significance = 0.005) and open-bottomed (Pearson correlation = 0.52, significance = 0.001) mesocosms. However, DGM and mercury volatilization were not significantly correlated (at the 95% level) in either of the mesocosms (significance = 0.09 in the closed mesocosm and significance = 0.9 in the open mesocosm). DGM concentrations decreased with depth (from 62 to 30 pg L(-1)) in the close-bottomed mesocosm but increased with depth (from 30 to 70 pg L(-1)) in the open-bottomed mesocosm suggesting a sediment source. DGM concentrations were found to be high in samples of ice melt (mean 73.6 pg L(-1), SD = 18.9, n=6) and snowmelt (mean 368.2 pg L(-1), SD = 115.8, n=4). These results suggest that sediment diffusion of mercury and melting snow and ice are important to DGM dynamics in frozen Lake St. Louis. These processes may also explain the lack of significant correlations observed in the DGM and mercury volatilization data.
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Affiliation(s)
- N J O'Driscoll
- Department of Earth & Environmental Science, Room LL33 K.C Irving Environmental Science Center, Acadia University, Wolfville, Nova Scotia.
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