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Chang C, Wang R, Xu L, Zhao Z, Cheng W, Hao J, Huang F. Historical co-enrichment, source attribution, and risk assessment of critical nutrients and heavy metal/metalloids in lake sediments: insights from Chaohu Lake, China. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2024; 46:390. [PMID: 39172153 DOI: 10.1007/s10653-024-02168-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/11/2024] [Indexed: 08/23/2024]
Abstract
In Chinese freshwater lakes, eutrophication often coincides with heavy metal/metalloids (HM/Ms) pollution, yet the coevolution of critical nutrients (P, S, Se) and HM/Ms (Cd, Hg, etc.) remains understudied. To address this gap, we conducted a sedimentary chemistry analysis on a 30 cm-deep core, dating back approximately 200 years, retrieved from Chaohu Lake, China. The age-depth model revealed a gradual increase in deposition rates over time. Notably, the concentrations and enrichment factors (EFs) of most target elements surged in the uppermost ~ 15 cm layer, covering the period from 1953 to 2013, while both the concentrations and EFs in deeper layers remained relatively stable, except for Hg. This trend indicates a significant co-enrichment and near-synchronous increase in the levels and EFs of both nutrients and HM/Ms in the upper sediment layers since the mid-twentieth century. Anthropogenic factors were identified as the primary drivers of the enrichment of P, Se, Cd, Hg, Zn, and Te in the upper core, with their contributions also showing a coupled evolutionary trend over time. Conversely, geological activities governed the enrichment of elements in the lower half of the core. The gradual accumulation of anthropogenic Hg between the - 30 to - 15 cm layers might be attributed to global Hg deposition resulting from the industrial revolution. The ecological risk index (RI) associated with HM/Ms loading has escalated rapidly over the past 50 years, with Cd and Hg posing the greatest threats. Furthermore, the PMF model was applied to specifically quantify source contributions of these elements in the core, with anthropogenic and geogenic factors accounting for ~ 60 and ~ 40%, respectively. A good correlation (r2 = 0.87, p < 0.01) between the PMF and Ti-normalized method was observed, indicating their feasibility and cross-validation in source apportionment. Finally, we highlighted environment impact and health implications of the co-enrichment of nutrients and HM/Ms. This knowledge is crucial for developing strategies to protect freshwater ecosystems from the combined impacts of eutrophication and HM/Ms pollution, thereby promoting water environment and human health.
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Affiliation(s)
- Chuanyu Chang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
- State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China.
| | - Ruirui Wang
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Liqiang Xu
- School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, 230009, China.
| | - Zhenjie Zhao
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, School of Public Health, Guizhou Medical University, Guiyang, 550025, China
| | - Wenhan Cheng
- College of Resources and Environment, Anhui Agriculture University, Hefei, 230036, Anhui, China
| | - Jihua Hao
- State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China
| | - Fang Huang
- State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China
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Wang Y, Zhang L, Chen X, Li C, Ding S, Yan J, Xiao J, Wang B, Xu L, Hang X. Algal-derived dissolved organic matter accelerates mercury methylation under cyanobacterial blooms in the sediment of eutrophic lakes. ENVIRONMENTAL RESEARCH 2024; 251:118734. [PMID: 38493854 DOI: 10.1016/j.envres.2024.118734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 02/17/2024] [Accepted: 03/14/2024] [Indexed: 03/19/2024]
Abstract
Mercury (Hg), especially in the form of methylmercury (MeHg), poses a significant threat to both organisms and the environment due to its extreme toxicity. While methylation process of Hg in sediments has been extensively studied, recognition of its associated risks and mechanisms during cyanobacterial blooms remains limited. This study investigated the distribution characteristics of Hg and MeHg in sediments of Taihu Lake, China. The concentration of Hg and MeHg varied within the range of 96.0-212.0 ng g-1 and 0.1-0.5 ng g-1, respectively. Higher ecological risks of Hg were found in algal-dominated regions compared to macrophyte areas. The significant correlations observed between Hg, MeHg, and algal-derived dissolved organic matter (ADOM) components C1 and C2 in algal-dominated regions indicate a close association between ADOM components and the Hg methylation process. These components are involved in the absorption or complexation of Hg, participate in redox reactions, and modulate microbial activity. The dsrB gene in sulfate-reducing bacteria (SRB) was found to accelerate the metabolic pathways of Hg methylation. These findings indicate that ADOM could enhance the methylation process of Hg during cyanobacterial blooms, which warrants attention.
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Affiliation(s)
- Yan Wang
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Lan Zhang
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Xiang Chen
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Cai Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Shiming Ding
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Jiabao Yan
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Jing Xiao
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China
| | - Bin Wang
- Zhongyifeng Construction Group Co., Ltd., Suzhou, 215131, China
| | - Lv Xu
- Anhui Urban Construction Design Institute Corp., Ltd, Hefei, 230051, China
| | - Xiaoshuai Hang
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing, 210042, China.
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Dai L, Zhang B, Liao X, Wang L, Zhang Q, Tian S, Liang T, O'Connor D, Rinklebe J. Catchment land use effect on mercury concentrations in lake sediments: A high-resolution study of Qinghai Lake. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170260. [PMID: 38253105 DOI: 10.1016/j.scitotenv.2024.170260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/24/2024]
Abstract
Mercury (Hg) contamination in aquatic environments presents a significant ecological and human health concern. This study explored the relationship between catchment land use and Hg concentrations within Qinghai Lake sediment, the largest lake in China, situated on the Qinghai-Tibet plateau. The study entailed detailed mapping of Hg sediment concentrations and a subsequent environmental risk assessment. Considering the complex nature of the plateau landform and surface vegetation, the study area was delineated at a 100 km radius centered on Qinghai Lake, which was divided into 30 sectors to quantify relationships between land use and the sediment Hg concentration. The results revealed a mean sediment Hg concentration of 29.91 μg/kg, which was elevated above the background level. Kendall's correlation analysis revealed significant but weak associations between sediment Hg concentrations and three land use types: grassland (rangeland and trees) (rs = 0.27, p < 0.05), crops (rs = -0.37, p < 0.05), and bare ground (rs = -0.25, p < 0.1), suggesting that growing areas of grassland correlated with higher Hg levels in the lake sediment, in contrast to bare ground or crops area, which correlated with lower Hg concentrations. Multiple linear regression models also observed weak negative relationships between bare ground and crops with sediment Hg concentration. This research methodology enhances our understanding of the impact of land use on Hg accumulation in lake sediments and underscores the need for integrated watershed management strategies to mitigate Hg pollution in Qinghai Lake.
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Affiliation(s)
- Lijun Dai
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Bo Zhang
- Beijing Municipal Ecological Environment Bureau, Beijing 100161, China
| | - Xiaoyong Liao
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
| | - Lingqing Wang
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Qian Zhang
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Shuhan Tian
- Department of Occupational and Environmental Health, School of Public Health, Qingdao University, Qingdao 266021, China
| | - Tao Liang
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - David O'Connor
- School of Real Estate and Land Management, Royal Agricultural University, Stroud Rd, Cirencester GL7 6JS, United Kingdom
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
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Kim YG, Kwon SY, Washburn SJ, Hong Y, Han SH, Lee M, Park JH. Environmental forensics approach to source investigation in a mercury contaminated river: Insights from mercury stable isotopes. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132559. [PMID: 37729710 DOI: 10.1016/j.jhazmat.2023.132559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/10/2023] [Accepted: 09/12/2023] [Indexed: 09/22/2023]
Abstract
Environmental forensics approach was applied to assess the efficacy of mercury (Hg) stable isotopes for source screening and decision-making in the Hyeongsan River, South Korea. Four Hg contamination scenarios were identified- atmospheric Hg emissions from a steel manufacturing industry, upstream riverine Hg transport, and industrial Hg releases and historical landfill collapse from Gumu Creek. The absence of significant Hg isotope difference between the Hyeongsan River sediments (δ202Hg; -0.46 ± 0.17‰, Δ199Hg; -0.04 ± 0.06‰) and the Gumu Creek sediment (δ202Hg; -0.39 ± 0.26‰, Δ199Hg; -0.04 ± 0.03‰) confirm that Hg source is originated from Gumu Creek. The heterogeneous Hg distribution throughout Gumu Creek and statistically similar Hg isotope ratios between Gumu Creek and solid waste cores from the landfill suggests that the landfill collapse is the dominant source to the Hyeongsan-Gumu system. Present Hg releases is also possible given the elevated and matching Δ199Hg between some riverine sediments and wastewater sampled from the landfill. The ternary mixing model estimates that the landfill collapse and wastewater releases contribute 61 ± 25 % and 22 ± 11 %, and the regional background, reflecting terrestrial runoff using deep sediment cores, explain 17 ± 24 % of Hg to the riverine sediment. We suggest that Hg isotopes can be used for routine source screening in areas where Hg sources are unknown.
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Affiliation(s)
- Young Gwang Kim
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, South Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, South Korea; Institute for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, South Korea.
| | - Spencer J Washburn
- Geosyntec Consultants, Inc., 100 Washington Ave. S, Suite 1590, Minneapolis, MN 55401, USA
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 2511 Sejong-Ro, Sejong City 30019, South Korea
| | - Seung Hee Han
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Buk-Gu, Gwangju 61005, South Korea
| | - Mikyung Lee
- Water Environmental Engineering Research Division, National Institute of Environmental Research, 42 Hwangyeong-Ro, Seo-Gu, Incheon 22689, South Korea
| | - Ji Hyoung Park
- Water Environmental Engineering Research Division, National Institute of Environmental Research, 42 Hwangyeong-Ro, Seo-Gu, Incheon 22689, South Korea
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Hu J, Zheng L, Liu S, Chen Y, Li C, Ni J, Chen Y, An S. Quantifying the impacts of coal mining activities on topsoil using Hg stable isotope: A case study of Guqiao mining area, Huainan City. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 335:122378. [PMID: 37586683 DOI: 10.1016/j.envpol.2023.122378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/30/2023] [Accepted: 08/12/2023] [Indexed: 08/18/2023]
Abstract
The Hg released from coal mining activities can endanger soil ecosystems and pose a risk to human health. Understanding the accumulation characteristics of mercury (Hg) in coal mining soil is important for effectively controlling Hg emissions and developing measures for the prevention and control of Hg contamination. To identify the potential sources of Hg in soils, the Hg concentration and isotopic composition characteristics of raw coal and different topsoil types from the areas surrounding a coal mine were determined in this study. The results showed that Hg in coal mainly exists mainly in the form of inorganic Hg, and Hg has experienced Hg2+ photoreduction prior to incorporating into coal. In addition, the composition of Hg isotopes differed significantly among different topsoil types, and the δ202Hg value of the farmland soil exhibited large negative excursions compared to the coal mining soil. The ternary mixed model further revealed the presence of substantial differences in potential Hg sources among the two regions, with the coal mining soil being greatly disturbed by anthropogenic activity, and the relative contributions of Hg from raw coal, coal gangue, and background soil to coal mining soil being 33.42%, 34.4%, and 32.19%, respectively. However, Hg from raw coal, coal gangue and background soil contributed 17.04%, 21.46%, and 61.51% of the Hg in the farmland soil, indicating that the accumulation of Hg in farmland soil was derived primarily from the background soil. Our study demonstrated that secondary pollution in soil caused by immense accumulation of solid waste (gangue) by mining activities offers a significant challenge to ecological security. These findings provide new insights into controlling soil Hg in mining areas and further highlight the urgency of strict protective measures for contaminated sites.
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Affiliation(s)
- Jie Hu
- School of Resources and Environmental Engineering, Anhui University, Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, 230601, Anhui, China
| | - Liugen Zheng
- School of Resources and Environmental Engineering, Anhui University, Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, 230601, Anhui, China.
| | - Sikui Liu
- School of Resources and Environmental Engineering, Anhui University, Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, 230601, Anhui, China
| | - Yeyu Chen
- School of Resources and Environmental Engineering, Anhui University, Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, 230601, Anhui, China
| | - Chang Li
- School of Resources and Environmental Engineering, Anhui University, Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, 230601, Anhui, China
| | - Jincheng Ni
- School of Resources and Environmental Engineering, Anhui University, Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, 230601, Anhui, China
| | - Yongchun Chen
- National Engineering Laboratory of Coal Mine Ecological Environment Protection, Huainan, 232001, Anhui, China
| | - Shikai An
- National Engineering Laboratory of Coal Mine Ecological Environment Protection, Huainan, 232001, Anhui, China
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Mao L, Ren W, Liu X, He M, Lin C, Zhong Y, Tang Y, Ouyang W. Tracking the multiple Hg sources in sediments in a typical river-lake basin by isotope compositions and mixing models. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132166. [PMID: 37531762 DOI: 10.1016/j.jhazmat.2023.132166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/04/2023]
Abstract
In this study, total mercury (THg) contents and Hg isotope compositions in sediments were investigated in the Lianxi River, Zijiang River and South Dongting Lake to identify and quantify multiple Hg sources and evaluate the Hg environmental processes. The THg contents, δ202Hg and Δ199Hg values in sediments were 48.22 ∼ 4284.32 µg/kg, - 1.33 ∼ 0.04‰ and - 0.25 ∼ 0.03‰, respectively. Relatively distinct Hg isotope characteristics of sediments were presented in the Lianxi River, Zijiang River and South Dongting Lake, indicating the dominant Hg sources considerably varied in these regions. Source apportionment based on MixSIAR proved that Hg in sediments mainly originated from industrial activities, and the ternary mixing model concluded non-ferrous metal smelting was the dominant industrial Hg contributor in the Lianxi River. Compared with the Lianxi River, the relative contribution of Hg in sediments from industrial activities significantly decreased, while the relative contributions of Hg from background releases significantly increased in the Zijiang River and South Dongting Lake. Nonetheless, the contribution of industrial Hg in this study area deserves more attention. These results are conducive to further manage Hg pollution.
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Affiliation(s)
- Lulu Mao
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Wenbo Ren
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xitao Liu
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
| | - Mengchang He
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Chunye Lin
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Ying Zhong
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550081 Guiyang, China
| | - Yang Tang
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550081 Guiyang, China
| | - Wei Ouyang
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Advanced Interdisciplinary Institute of Environment and Ecology, Beijing Normal University, Zhuhai 519087, China
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Sun R, Cao F, Dai S, Shan B, Qi C, Xu Z, Li P, Liu Y, Zheng W, Chen J. Atmospheric Mercury Isotope Shifts in Response to Mercury Emissions from Underground Coal Fires. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37167064 DOI: 10.1021/acs.est.2c08637] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Pollutant emissions from coal fires have caused serious concerns in major coal-producing countries. Great efforts have been devoted to suppressing them in China, notably at the notorious Wuda Coalfield in Inner Mongolia. Recent surveys revealed that while fires in this coalfield have been nearly extinguished near the surface, they persist underground. However, the impacts of Hg volatilized from underground coal fires remain unclear. Here, we measured concentrations and isotope compositions of atmospheric Hg in both gaseous and particulate phases at an urban site near the Wuda Coalfield. The atmospheric Hg displayed strong seasonality in terms of both Hg concentrations (5-7-fold higher in fall than in winter) and isotope compositions. Combining characteristic isotope compositions of potential Hg sources and air mass trajectories, we conclude that underground coal fires were still emitting large amounts of Hg into the atmosphere that have been transported to the adjacent urban area in the prevailing downwind direction. The other local anthropogenic Hg emissions were only evident in the urban atmosphere when the arriving air masses did not pass directly through the coalfield. Our study demonstrates that atmospheric Hg isotope measurement is a useful tool for detecting concealed underground coal fires.
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Affiliation(s)
- Ruoyu Sun
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Fei Cao
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Shifeng Dai
- College of Geoscience and Survey Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
| | - Bing Shan
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Cuicui Qi
- Anhui Academy of Eco-environmental Science Research, Hefei 230071, China
| | - Zhanjie Xu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Pengfei Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Yi Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Wang Zheng
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Jiubin Chen
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
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Taylor VF, Landis JD, Janssen SE. Tracing the sources and depositional history of mercury to coastal northeastern U.S. lakes. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:1805-1820. [PMID: 36065894 DOI: 10.1039/d2em00214k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) deposition was reconstructed in sediment cores from lakes in two coastal U.S. National Parks: Acadia National Park (ANP) and Cape Cod National Seashore (CCNS), to fill an important spatial gap in Hg deposition records and to explore changing sources of Hg and processes affecting Hg accumulation in these coastal sites. Recent Hg deposition chronology was assessed using (1) a newly developed lead-210 (210Pb) based sediment age model which employs 7Be to constrain deposition and sediment mixing of 210Pb-excess, (2) coinciding Pb flux and isotope ratios (206Pb/207Pb), and (3) Hg isotope ratios and their response to changes in Hg flux. At both sites, Hg flux increased substantially from pre-1850 levels, with accumulation in ANP peaking in the 1970s, whereas in CCNS, Hg levels were highest in recent sediments. Negative values of δ202Hg and Δ199Hg indicated terrestrially-derived Hg was a major constituent of Hg flux to Sargent Mountain Pond, ANP, although recent decreases in Hg flux were in agreement with precipitation Hg records, indicating a rapid watershed response. By contrast, δ202Hg and Δ199Hg profiles in Long Pond, CNNS reflect direct Hg deposition, but disturbances in the sedimentary record were indicated by bomb fallout radionuclide inventories and by peaks in both Pb and Hg isotope depth profiles. These cores provided poor reconstructions of atmospheric deposition and reveal responses that are decoupled from emissions reduction due to complex post-depositional redistribution of atmospheric metals including Hg. The application of multiple tracers of Hg deposition provide insight into the sources and pathways governing Hg accumulation in these lakes.
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Affiliation(s)
- Vivien F Taylor
- Department of Earth Science, 6105 Fairchild Hall, Dartmouth College, Hanover, NH 03755, USA.
| | - Joshua D Landis
- Department of Earth Science, 6105 Fairchild Hall, Dartmouth College, Hanover, NH 03755, USA.
| | - Sarah E Janssen
- U.S. Geological Survey Upper Midwest Water Science Center, Mercury Research Lab, 1 Gifford Pinchot Dr, Madison, WI 53726, USA
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