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Zhang H, Fu X, Wu X, Deng Q, Tang K, Zhang L, Sommar J, Sun G, Feng X. Using Mercury Stable Isotopes to Quantify Bidirectional Water-Atmosphere Hg(0) Exchange Fluxes and Explore Controlling Factors. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37378655 DOI: 10.1021/acs.est.3c01273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
In this study, exchange fluxes and Hg isotope fractionation during water-atmosphere Hg(0) exchange were investigated at three lakes in China. Water-atmosphere exchange was overall characterized by net Hg(0) emissions, with lake-specific mean exchange fluxes ranging from 0.9 to 1.8 ng m-2 h-1, which produced negative δ202Hg (mean: -1.61 to -0.03‰) and Δ199Hg (-0.34 to -0.16‰) values. Emission-controlled experiments conducted using Hg-free air over the water surface at Hongfeng lake (HFL) showed negative δ202Hg and Δ199Hg in Hg(0) emitted from water, and similar values were observed between daytime (mean δ202Hg: -0.95‰, Δ199Hg: -0.25‰) and nighttime (δ202Hg: -1.00‰, Δ199Hg: -0.26‰). Results of the Hg isotope suggest that Hg(0) emission from water is mainly controlled by photochemical Hg(0) production in water. Deposition-controlled experiments at HFL showed that heavier Hg(0) isotopes (mean ε202Hg: -0.38‰) preferentially deposited to water, likely indicating an important role of aqueous Hg(0) oxidation played during the deposition process. A Δ200Hg mixing model showed that lake-specific mean emission fluxes from water surfaces were 2.1-4.1 ng m-2 h-1 and deposition fluxes to water surfaces were 1.2-2.3 ng m-2 h-1 at the three lakes. Results from the this study indicate that atmospheric Hg(0) deposition to water surfaces indeed plays an important role in Hg cycling between atmosphere and water bodies.
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Affiliation(s)
- Hui Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xian Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qianwen Deng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaihui Tang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Leiming Zhang
- Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto M3H5T4, Ontario, Canada
| | - Jonas Sommar
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Guangyi Sun
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Wang X, Xie Q, Wang Y, Lü H, Fu M, Wang D, Li J. Hg bioaccumulation in the aquatic food web from tributaries of the Three Gorges Reservoir, China and potential consumption advisories. JOURNAL OF HAZARDOUS MATERIALS 2023; 458:131902. [PMID: 37364435 DOI: 10.1016/j.jhazmat.2023.131902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/04/2023] [Accepted: 06/18/2023] [Indexed: 06/28/2023]
Abstract
The Three Gorges Reservoir (TGR) holds the distinction of being China's largest reservoir, and the presence of pollutants in the fish from the reservoir have a direct impact on the health of local residents. Thus, 349 fish specimens of 21 species and 1 benthos (Bellamya aeruginosas) were collected from four typical tributaries of the TGR from 2019 to 2020. These specimens were analyzed for the concentrations of total mercury (THg) and methylmercury (MeHg), and some representative samples were tested for δ13C and δ15N values to reveal the characteristics of bioaccumulation and biomagnification. The maximum safe daily consumption was estimated based on the oral reference dose (0.1 μg kg-1 bw/day according to US-EPA, 2017). The results showed that the mean THg and MeHg concentrations in fish from the TGR tributaries were 73.18 ± 49.21 ng g-1 and 48.42 ± 40.66 ng g-1, respectively, with the trophic magnification factors (TMFs) of THg and MeHg being 0.066 and 0.060, respectively. Among all the fish species in the tributaries, the highest daily maximum safe consumption amount was 1253.89 g for S. asotus consumed by adults, while the lowest was 62.88 g for C. nasus consumed by children.
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Affiliation(s)
- Xueheng Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China; College of Fisheries, Southwest University, Chongqing 400715, China
| | - Qing Xie
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China; College of Resources, Environment and Safety, Chongqing Vocational Institute of Engineering, Chongqing 402260, China; College of Fisheries, Southwest University, Chongqing 400715, China
| | - Yongmin Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China; College of Fisheries, Southwest University, Chongqing 400715, China
| | - Hongjian Lü
- College of Fisheries, Southwest University, Chongqing 400715, China; National Base of International S&T Collaboration on Water Environmental Monitoring and Simulation in Three Gorges Reservoir Region, Chongqing 400715, China
| | - Mei Fu
- College of Fisheries, Southwest University, Chongqing 400715, China; National Base of International S&T Collaboration on Water Environmental Monitoring and Simulation in Three Gorges Reservoir Region, Chongqing 400715, China
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China; College of Fisheries, Southwest University, Chongqing 400715, China.
| | - Jiajia Li
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China; College of Fisheries, Southwest University, Chongqing 400715, China; National Base of International S&T Collaboration on Water Environmental Monitoring and Simulation in Three Gorges Reservoir Region, Chongqing 400715, China.
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Chemical Oxidation and Reduction Pathways of Mercury Relevant to Natural Waters: A Review. WATER 2022. [DOI: 10.3390/w14121891] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mercury (Hg) pollution in the environment is a global issue and the toxicity of mercury depends on its speciation. Chemical redox reactions of mercury in an aquatic environment greatly impact on Hg evasion to the atmosphere and the methylation of mercury in natural waters. Identifying the abiotic redox pathways of mercury relevant to natural waters is important for predicting the transport and fate of Hg in the environment. The objective of this review is to summarize the current state of knowledge on specific redox reactions of mercury relevant to natural waters at a molecular level. The rate constants and factors affecting them, as well as the mechanistic information of these redox pathways, are discussed in detail. Increasing experimental evidence also implied that the structure of natural organic matter (NOM) play an important role in dark Hg(II) reduction, dark Hg(0) oxidation and Hg(II) photoreduction in the aquatic environment. Significant photooxidation pathways of Hg(0) identified are Hg(0) photooxidation by hydroxyl radical (OH•) and by carbonate radical (CO3−•). Future research needs on improving the understanding of Hg redox cycling in natural waters are also proposed.
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Vudamala K, Chakraborty P, Sailaja BBV. An insight into mercury reduction process by humic substances in aqueous medium under dark condition. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:14499-14507. [PMID: 28447253 DOI: 10.1007/s11356-017-8979-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 04/03/2017] [Indexed: 06/07/2023]
Abstract
Mercury (Hg) reduction by humic substances (HS) in the aquatic medium under the dark condition is a poorly understood but important process in Hg biogeochemical cycling. In this study, an effort was made to provide a better understanding of Hg(II) reduction by well-characterized humic substances under dark condition. Reduction of Hg(II) by dissolved HS in aquatic systems increases with increasing Hg loading. However, Hg(II) reduction gradually decreases with the increasing total S content and oxygen containing functional groups in the dissolved HS under dark condition. Increasing major cation concentration decreases the rate of Hg(II) reduction in aquatic systems. High concentration of Ca2+ ion slows down the intermolecular electron transfer from HS to Hg(II) and inhibits the formation of Hg0 in absence of light. This study indicates that complexation of Hg(II) and HS is essential for Hg reduction under dark condition.
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Affiliation(s)
- Krushna Vudamala
- CSIR-National Institute of Oceanography, Dona Paula, Goa, 403004, India
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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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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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Canário J, Poissant L, O'Driscoll N, Vale C, Pilote M, Lean D. Sediment processes and mercury transport in a frozen freshwater fluvial lake (Lake St. Louis, QC, Canada). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2009; 157:1294-1300. [PMID: 19117652 DOI: 10.1016/j.envpol.2008.11.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 05/27/2023]
Abstract
An open-bottom and a closed-bottom mesocosm were developed to investigate the release of mercury from sediments to the water column in a frozen freshwater lake. The mesoscosms were deployed in a hole in the ice and particulate mercury (Hg(P)) and total dissolved mercury (TDHg) were measured in sediments and in water column vertical profiles. In addition, dissolved gaseous mercury (DGM) in water and mercury water/airflux were quantified. Concentrations of TDHg, DGM, and mercury flux were all higher in the open-bottom mesocosm than in the closed-bottom mesocosm. In this paper we focus on the molecular diffusion of mercury from the sediment in comparison with the TDHg accumulation in the water column. We conclude that the molecular diffusion and sediment resuspension play a minor role in mercury release from sediments suggesting that solute release during ebullition is an important transport process for mercury in the lake.
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Affiliation(s)
- João Canário
- IPIMAR/National Institute of Biological Resources, Lisboa, Portugal.
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