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Sánchez-Fortún M, Carrasco JL, Díez S, Amouroux D, Tessier E, López-Carmona S, Sanpera C. Temporal mercury dynamics throughout the rice cultivation season in the Ebro Delta (NE Spain): An integrative approach. ENVIRONMENTAL RESEARCH 2024; 250:118555. [PMID: 38412914 DOI: 10.1016/j.envres.2024.118555] [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: 12/21/2023] [Revised: 02/23/2024] [Accepted: 02/24/2024] [Indexed: 02/29/2024]
Abstract
During the last few decades, inputs of mercury (Hg) to the environment from anthropogenic sources have increased. The Ebro Delta is an important area of rice production in the Iberian Peninsula. Given the industrial activity and its legacy pollution along the Ebro river, residues containing Hg have been transported throughout the Ebro Delta ecosystems. Rice paddies are regarded as propitious environments for Hg methylation and its subsequent incorporation to plants and rice paddies' food webs. We have analyzed how Hg dynamics change throughout the rice cultivation season in different compartments from the paddies' ecosystems: soil, water, rice plants and fauna. Furthermore, we assessed the effect of different agricultural practices (ecological vs. conventional) associated to various flooding patterns (wet vs. mild alternating wet and dry) to the Hg levels in rice fields. Finally, we have estimated the proportion of methylmercury (MeHg) to total mercury in a subset of samples, as MeHg is the most bioaccumulable toxic form for humans and wildlife. Overall, we observed varying degrees of mercury concentration over the rice cultivation season in the different compartments. We found that different agricultural practices and flooding patterns did not influence the THg levels observed in water, soil or plants. However, Hg concentrations in fauna samples seemed to be affected by hydroperiod and we also observed evidence of Hg biomagnification along the rice fields' aquatic food webs.
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Affiliation(s)
- Moisès Sánchez-Fortún
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain.
| | - Josep Lluís Carrasco
- Biostatistics, Department of Basic Clinical Practice, University of Barcelona, Barcelona, Spain.
| | - Sergi Díez
- Environmental Chemistry Department, Institute of Environmental Assessment and Water Research, IDAEA-CSIC, E-08034, Barcelona, Spain.
| | - David Amouroux
- Université de Pau et des Pays de L'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux, Pau, France.
| | - Emmanuel Tessier
- Université de Pau et des Pays de L'Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux, Pau, France.
| | - Sophie López-Carmona
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; UFR Sciences et Techniques, Université de Nantes, Nantes, France.
| | - Carola Sanpera
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain.
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2
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Salvato LA, Marvin-DiPasquale M, Fleck JA, McCord SA, Linquist BA. Influence of irrigation water and soil on annual mercury dynamics in Sacramento Valley rice fields. JOURNAL OF ENVIRONMENTAL QUALITY 2024; 53:327-339. [PMID: 38468600 DOI: 10.1002/jeq2.20557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 01/30/2024] [Indexed: 03/13/2024]
Abstract
Methylmercury (MeHg) is a human and environmental toxin produced in flooded soils. Little is known about MeHg in rice (Oryza Sativa L.) fields in Sacramento Valley, California. The objectives of this study were to quantify mercury fractions in irrigation water and within rice fields and to determine their mercury pools in surface water, soil, and grain. Soil, grain, and surface water (dissolved and particulate) MeHg and total mercury (THg) were monitored in six commercial rice fields throughout a winter fallow season and subsequent growing season. Both dissolved and particulate mercury fractions were higher in fallow season rice field water. Total suspended solids and particulate mercury concentrations were positively correlated (r = 0.99 and 0.98 for THg and MeHg, respectively), suggesting that soil MeHg was suspended in the water column and potentially exported. Dissolved THg and MeHg concentrations were positively correlated with absorbance at 254 nm (r = 0.47 and 0.58, respectively) in fallow season field water. In the growing season, fields with higher irrigation water MeHg concentrations (due to recycled water use) had elevated field-water MeHg (r = 0.86) and grain MeHg concentrations (r = 0.96). Based on a mass balance analysis, soil mercury pools were orders of magnitude larger than surface water or grain mercury pools; however, fallow season drainage and grain harvest were the primary pathways for MeHg export. Based on these findings, reducing (1) discharge when water is turbid, (2) straw inputs, and (3) use of recycled irrigation water could help reduce mercury exports in rice field drainage water.
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Affiliation(s)
- Luke A Salvato
- Department of Plant Sciences, University of California, Davis, California, USA
| | | | - Jacob A Fleck
- California Water Science Center, US Geological Survey, Sacramento, California, USA
| | | | - Bruce A Linquist
- Department of Plant Sciences, University of California, Davis, California, USA
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3
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Fernandes IO, Monteiro LC, de Miranda VL, Rodrigues YOS, de Freitas Muniz DH, de Castro Paes É, Bernardi JVE. Mercury distribution in organisms, litter, and soils of the Middle Araguaia floodplain in Brazil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:20925-20940. [PMID: 38379047 DOI: 10.1007/s11356-024-32317-x] [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: 12/28/2022] [Accepted: 01/29/2024] [Indexed: 02/22/2024]
Abstract
Mercury (Hg) is a chemical element that, depending on its concentration, may become toxic to living organisms due to the ability of Hg to bioaccumulate in food chains. In this study, we collected samples of soil, litter, and organisms in the Middle Araguaia floodplain, Brazil. Total mercury (THg) concentrations in litter were significantly higher (p < 0.0001) than that in soil, ranging from 10.68 ± 0.55 to 48.94 ± 0.13 and 20.80 ± 1.07 to 55 .19 ± 1.59 ng g-1, respectively. Total mercury concentration levels in soil showed a linear, inversely proportional relationship with soil organic matter (SOM) contents and soil pH, consistent with the geochemical behavior of chemical elements in flooded environments. Ten orders of organisms were identified, and the average THg concentrations determined in their bodies were up to 20 times higher than those in soil and litter. We found a significant linear relationship between the levels of THg in litter and those found in soil organisms, thereby allowing the prediction of THg concentration levels in soil organisms through the analysis of litter at the sample units. The different dynamics and feeding habits of soil organisms and the concentration of THg in these organisms may be influenced by the river's course. This study provides evidence of the bioaccumulation of THg in soil organisms in the floodplain of the Middle Araguaia River, an important river basin in the Brazilian savanna.
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Affiliation(s)
- Iara Oliveira Fernandes
- Graduate Program in Environmental Sciences, Faculty UnB Planaltina, University of Brasília, Planaltina, Distrito Federal, 73345-010, Brazil.
| | - Lucas Cabrera Monteiro
- Graduate Program in Ecology, Institute of Biological Sciences, University of Brasília, Brasília, Distrito Federal, 70910-900, Brazil
| | - Vinícius Lima de Miranda
- Graduate Program in Zoology, Institute of Biological Sciences, University of Brasília, Brasília, Distrito Federal, 70910-900, Brazil
| | - Ygor Oliveira Sarmento Rodrigues
- Graduate Program in Environmental Sciences, Faculty UnB Planaltina, University of Brasília, Planaltina, Distrito Federal, 73345-010, Brazil
| | - Daphne Heloisa de Freitas Muniz
- Graduate Program in Environmental Sciences, Faculty UnB Planaltina, University of Brasília, Planaltina, Distrito Federal, 73345-010, Brazil
| | - Ésio de Castro Paes
- Graduate Program in Soils and Plant Nutrition, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil
| | - José Vicente Elias Bernardi
- Graduate Program in Environmental Sciences, Faculty UnB Planaltina, University of Brasília, Planaltina, Distrito Federal, 73345-010, Brazil
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4
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Hall LA, Woo I, Marvin-DiPasquale M, Takekawa JY, Krabbenhoft DP, Yee D, Grenier L, De La Cruz SEW. Linking Mesoscale Spatial Variation in Methylmercury Production to Bioaccumulation in Tidal Marsh Food Webs. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:19263-19273. [PMID: 37956992 DOI: 10.1021/acs.est.3c04907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
Differences in sediment biogeochemistry among tidal marsh features with different hydrological and geomorphological characteristics, including marsh interiors, marsh edges, first-order channels, and third-order channels, can result in spatial variation in MeHg production and availability. To better understand the link between MeHg production in sediments and bioaccumulation in primary and secondary consumer invertebrates and fish, we characterized mesoscale spatial variation in sediment biogeochemistry and MeHg concentrations of sediments, water, and consumer tissues among marsh features. Our results indicated that marsh interiors had biogeochemical conditions, including greater concentrations of organic matter and sulfate reduction rates, that resulted in greater MeHg concentrations in sediments and surface water particulates from marsh interiors compared to other features. Tissue MeHg concentrations of consumers also differed among features, with greater concentrations from marsh edges and interiors compared to channels. This spatial mismatch of MeHg concentrations in sediments and water compared to those in consumers may have resulted from differences in behavior and physiology among consumers that influenced the spatial scale over which MeHg was integrated into tissues. Our results highlight the importance of sampling across a suite of marsh features and considering the behavioral and physiological traits of sentinel taxa for contaminant monitoring studies.
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Affiliation(s)
- Laurie A Hall
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, NASA Research Park Bldg. 19, N. Akron Road, Moffett Field, California 94035, United States
| | - Isa Woo
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, NASA Research Park Bldg. 19, N. Akron Road, Moffett Field, California 94035, United States
| | - Mark Marvin-DiPasquale
- U.S. Geological Survey, Water Mission Area, Earth System Processes Division, 345 Middlefield Road, Menlo Park, California 94025, United States
| | - John Y Takekawa
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, NASA Research Park Bldg. 19, N. Akron Road, Moffett Field, California 94035, United States
| | - David P Krabbenhoft
- U.S. Geological Survey, Mercury Research Laboratory, 8505 Research Way, Middleton, Wisconsin 53562, United States
| | - Donald Yee
- San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804, United States
| | - Letitia Grenier
- San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804, United States
| | - Susan E W De La Cruz
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, NASA Research Park Bldg. 19, N. Akron Road, Moffett Field, California 94035, United States
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5
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Liu M, Mason RP, Vlahos P, Whitney MM, Zhang Q, Warren JK, Wang X, Baumann Z. Riverine Discharge Fuels the Production of Methylmercury in a Large Temperate Estuary. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:13056-13066. [PMID: 37603456 DOI: 10.1021/acs.est.3c00473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Estuaries are an important food source for the world's growing population, yet human health is at risk from elevated exposure to methylmercury (MeHg) via the consumption of estuarine fish. Moreover, the sources and cycling of MeHg in temperate estuarine ecosystems are poorly understood. Here, we investigated the seasonal and tidal patterns of mercury (Hg) forms in Long Island Sound (LIS), in a location where North Atlantic Ocean waters mix with the Connecticut River. We found that seasonal variations in Hg and MeHg in LIS followed the extent of riverine Hg delivery, while tides further exacerbated the remobilization of earlier deposited riverine Hg. The net production of MeHg near the river plume was significant compared to that in other locations and enhanced during high tide, possibly resulting from the enhanced microbial activity and organic carbon remineralization in the river plume. Statistical models, driven by our novel data, further support the hypothesis that the river-delivered organic matter and inorganic Hg drive net MeHg production in the estuarine water column. Our study sheds light on the significance of water column biogeochemical processes in temperate tidal estuaries in regulating MeHg levels and inspires new questions in our quest to understand MeHg sources and dynamics in coastal oceans.
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Affiliation(s)
- Maodian Liu
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Science, Peking University, Beijing 100871, China
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States
- School of the Environment, Yale University, New Haven, Connecticut 06511, United States
| | - Robert P Mason
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States
| | - Penny Vlahos
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States
| | - Michael M Whitney
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States
| | - Qianru Zhang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Science, Peking University, Beijing 100871, China
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Joseph K Warren
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States
| | - Xuejun Wang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Science, Peking University, Beijing 100871, China
| | - Zofia Baumann
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States
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6
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Yang N, Hu J, Yin D, He T, Tian X, Ran S, Zhou X. Mercury and methylmercury in Hg-contaminated paddy soil and their uptake in rice as regulated by DOM from different agricultural sources. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27712-9. [PMID: 37249779 DOI: 10.1007/s11356-023-27712-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/13/2023] [Indexed: 05/31/2023]
Abstract
In this study, from the perspectives of structural and compositional variations of soil-dissolved organic matter (DOM), we explored the effects of agricultural DOM inputs on methylmercury (MeHg) accumulation in the soil and mercury (Hg) bioaccumulation in rice grains. Pot experiments with the addition of DOMs from maize straw (MaS), rape straw (RaS), rice straw (RiS), composted rice straw (CRiS), cow dung (CD), and composted cow dung (CCD) were then conducted. Results showed that, relative to the control, the DOM amendment from each agricultural source elevated MeHg concentrations in the soil, with an increase of 18-227%, but only parts of DOMs elevated total dissolved Hg (DHg) and MeHg (DMeHg) concentrations in pore water. Among all DOM species, RiS, CRiS, and CCD significantly increased total Hg (THg) and MeHg contents in rice grains by 34-64% and 32-118%, respectively. Compared with RiS, THg and MeHg contents in rice grains in the CRiS treatment decreased slightly, which was consistent with the distributions of DHg and DMeHg concentrations in pore water and the aromaticity variation of soil DOM. In contrast, the CCD input significantly enhanced the enrichment of THg and MeHg in rice grains relative to CD because it significantly reduced the humification of soil DOM at all rice-growing stages while increasing the low-molecular-weight fractions in soil DOM. The THg and MeHg contents in the rice grains were significantly lower treated by RaS than those by MaS and RiS, which may be related to the higher sulfur-containing compounds such as sulfate and cysteine in rape straw or its DOM solution. Overall, DOM amendment from different agricultural sources resulted in significantly discriminative effects on the MeHg accumulation in soil and Hg enrichment in rice in the Hg-contaminated paddy field by shaping soil DOM properties.
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Affiliation(s)
- Ningla Yang
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Jie Hu
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China.
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China.
| | - Xiang Tian
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Shu Ran
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
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7
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Li Y, Zhu N, Hu W, Liu YR, Jia W, Lin G, Li H, Li Y, Gao Y, Zhao J. New insights into sulfur input induced methylmercury production and accumulation in paddy soil and rice. JOURNAL OF HAZARDOUS MATERIALS 2023; 455:131602. [PMID: 37178535 DOI: 10.1016/j.jhazmat.2023.131602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 05/05/2023] [Accepted: 05/08/2023] [Indexed: 05/15/2023]
Abstract
Sulfur has a high affinity for mercury (Hg) and can serve as effective treating agent for Hg pollution. However, conflict effects between reducing Hg mobility and promoting Hg methylation by sulfur were found in recent studies, and there is a gap in understanding the potential mechanism of MeHg production under different sulfur-treated species and doses. Here, we investigated and compared the MeHg production in Hg-contaminated paddy soil and its accumulation in rice under elemental sulfur or sulfate treatment at a relatively low (500 mg·kg-1) or high (1000 mg·kg-1) level. The associated potential molecular mechanisms are also discussed with the help of density functional theory (DFT) calculation. Pot experiments demonstrate that both elemental sulfur and sulfate at high exposure levels increased MeHg production in soil (244.63-571.72 %) and its accumulation in raw rice (268.73-443.50 %). Coupling the reduction of sulfate or elemental sulfur and decrease of soil redox potential leads to the detachment of Hg-polysulfide complexes from the surface of HgS which can be explained by DFT calculations. Enhancement of free Hg and Fe release through reducing Fe(III) oxyhydroxides further promotes soil MeHg production. The results provide clues for understanding the mechanism by which exogenous sulfur promotes MeHg production in paddies and paddy-like environments and give new insights for decreasing Hg mobility by regulating soil conditions.
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Affiliation(s)
- Yunyun Li
- Fujian Provincial Key Laboratory of Ecology-Toxicological Effects & Control for Emerging Contaminants, Key Laboratory of Ecological Environment and Information Atlas, College of Environmental and Biological Engineering, Putian University, Putian 351100, China; Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
| | - Nali Zhu
- School of Environment, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
| | - Wenjun Hu
- Fujian Provincial Key Laboratory of Ecology-Toxicological Effects & Control for Emerging Contaminants, Key Laboratory of Ecological Environment and Information Atlas, College of Environmental and Biological Engineering, Putian University, Putian 351100, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Wen Jia
- Fujian Provincial Key Laboratory of Ecology-Toxicological Effects & Control for Emerging Contaminants, Key Laboratory of Ecological Environment and Information Atlas, College of Environmental and Biological Engineering, Putian University, Putian 351100, China
| | - Guoming Lin
- Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore 117557, Singapore.
| | - Hong Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yufeng Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Jiating Zhao
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
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8
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Sonke JE, Angot H, Zhang Y, Poulain A, Björn E, Schartup A. Global change effects on biogeochemical mercury cycling. AMBIO 2023; 52:853-876. [PMID: 36988895 PMCID: PMC10073400 DOI: 10.1007/s13280-023-01855-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 02/07/2023] [Accepted: 03/03/2023] [Indexed: 06/18/2023]
Abstract
Past and present anthropogenic mercury (Hg) release to ecosystems causes neurotoxicity and cardiovascular disease in humans with an estimated economic cost of $117 billion USD annually. Humans are primarily exposed to Hg via the consumption of contaminated freshwater and marine fish. The UNEP Minamata Convention on Hg aims to curb Hg release to the environment and is accompanied by global Hg monitoring efforts to track its success. The biogeochemical Hg cycle is a complex cascade of release, dispersal, transformation and bio-uptake processes that link Hg sources to Hg exposure. Global change interacts with the Hg cycle by impacting the physical, biogeochemical and ecological factors that control these processes. In this review we examine how global change such as biome shifts, deforestation, permafrost thaw or ocean stratification will alter Hg cycling and exposure. Based on past declines in Hg release and environmental levels, we expect that future policy impacts should be distinguishable from global change effects at the regional and global scales.
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Affiliation(s)
- Jeroen E. Sonke
- Géosciences Environnement Toulouse, CNRS/IRD, Université Paul Sabatier Toulouse 3, 14 ave Edouard Belin, 31400 Toulouse, France
| | - Hélène Angot
- Univ. Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE, 1025 rue de la piscine, 38000 Grenoble, France
| | - Yanxu Zhang
- School of Atmospheric Sciences, Nanjing University, 163 Xianlin Road, Nanjing, 210023 Jiangsu China
| | - Alexandre Poulain
- Department of Biology, University of Ottawa, Ottawa, ON K1N6N5 Canada
| | - Erik Björn
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Amina Schartup
- Geosciences Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 USA
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9
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Willacker JJ, Eagles-Smith CA, Nelson SJ, Flanagan Pritz CM, Krabbenhoft DP. The influence of short-term temporal variability on the efficacy of dragonfly larvae as mercury biosentinels. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 867:161469. [PMID: 36632899 DOI: 10.1016/j.scitotenv.2023.161469] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/04/2023] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
Mercury (Hg) exposure to fish, wildlife, and humans is widespread and of global concern, thus stimulating efforts to reduce emissions. Because the relationships between rates of inorganic Hg loading, methylmercury (MeHg) production, and bioaccumulation are extremely complex and challenging to predict, there is a need for reliable biosentinels to understand the distribution of Hg in the environment and monitor the effectiveness of reduction efforts. However, it is important to assess how temporal and spatial variation at multiple scales influences the efficacy of specific biosentinels. Seasonal and interannual variation in total Hg (THg) concentrations of dragonfly larvae were examined in relation to spatial variability among 21 sites in two U.S. national parks with contrasting ecologies and Hg deposition patterns. Dragonfly THg differed among sampling events at 17 of the 21 sites, but by an average of only 20.4 % across events, compared to an average difference of 52.7 % among sites. Further, THg concentrations did not follow consistent seasonal patterns across sites or years, suggesting that the observed temporal variation was unlikely to bias monitoring efforts. Importantly, for a specific site, there was no difference in % MeHg in dragonflies among sampling events. Finally, there was significant temporal variability in the biogeochemical factors (aqueous inorganic Hg, aqueous MeHg, DOC, SO4, and pH) influencing dragonfly THg, with the importance of individual factors varying by 2.4 to 4.3-fold across sampling events. Despite these results, it is noteworthy that the observed temporal variation in dragonfly THg concentrations was neither large nor consistent enough to bias spatial assessments. Thus, although this temporal variation may provide insights into the processes influencing biological Hg concentrations, it is unlikely to impair the use of dragonflies as biosentinels for monitoring spatial or temporal patterns at scales relevant to most mitigation efforts.
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Affiliation(s)
- James J Willacker
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97331, USA.
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Sarah J Nelson
- Appalachian Mountain Club, 361 Route 16, Gorham, NH 03581, USA
| | | | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, 1 Gifford Pinchot Dr, Madison, WI 53726, USA
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10
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Hu H, Gao Y, Yu H, Xiao H, Chen S, Tan W, Tang J, Xi B. Mechanisms and biological effects of organic amendments on mercury speciation in soil-rice systems: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 251:114516. [PMID: 36628877 DOI: 10.1016/j.ecoenv.2023.114516] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and biomagnification effects. As the largest global Hg reservoir, the Hg cumulatively stored in soils has reached as high as 250-1000 Gg. Even more concerning is that global soil-rice systems distributed in many countries have become central to the global Hg cycle because they are both a major food source for more than 3 billion people worldwide and the central bridge linking atmospheric and soil Hg circulation. In this review, we discuss the form distribution, transformation, and bioavailability of Hg in soil-rice systems by focusing on the Hg methylation and demethylation pathways and distribution, uptake, and accumulation in rice plants and the effects of Hg on the community structure and ecological functions of microorganisms in soil-rice systems. In addition, we clarify the mechanisms through which commonly used humus and biochar organic amendments influence Hg and its environmental effects in soil-rice systems. The review also elaborates on the advantages of sulfur-modified biochars and their critical role in controlling Hg migration and bioavailability in soils. Finally, we provide key information about Hg pollution in soil-rice systems, which is of great significance for developing appropriate strategies and mitigation planning to limit Hg bioconcentration in rice crops and achieving key global sustainable development goals, such as the guarantee of food security and the promotion of sustainable agriculture.
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Affiliation(s)
- Hualing Hu
- Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Yiman Gao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Hanxia Yu
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Haoyan Xiao
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Shuhe Chen
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Wenbing Tan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Jun Tang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Beidou Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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11
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Li C, Luo K, Shao Y, Xu X, Chen Z, Liang T, Xu Z, Dong X, Wang H, Qiu G. Total and methylmercury concentrations in nocturnal migratory birds passing through Mount Ailao, Southwest China. ENVIRONMENTAL RESEARCH 2022; 215:114373. [PMID: 36165871 DOI: 10.1016/j.envres.2022.114373] [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: 05/16/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
Despite growing concerns over mercury (Hg) accumulation in birds in recent decades, little is known about Hg exposure in nocturnal migratory birds. Here, total mercury (THg) and methylmercury (MeHg) were detected in the feathers of nocturnal migratory birds (n = 286, belonging to 46 species) passing through Mount Ailao in Southwest China. The stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were also determined to clarify the effects of trophic position, foraging guild, and foraging behavior on Hg bioaccumulation. Our results show that the THg and MeHg concentrations varied by two orders of magnitude among all nocturnal migratory birds investigated, with the lowest values (THg: 0.056 mg kg-1; MeHg: 0.038 mg kg-1) in the Asian koel (Eudynamys scolopaceus) and the highest (THg: 12 mg kg-1; MeHg: 7.8 mg kg-1) in the hair-crested drongo (Dicrurus hottentottus). Waterbirds showed higher δ15N values and higher THg and MeHg concentrations than songbirds, and the Hg concentrations in piscivorous species were significantly higher than those in herbivores, omnivores, and insectivores. Significant effects of foraging guilds (Kruskal-Wallis one-way ANOVA, p < 0.001) and foraging behaviors (Kruskal-Wallis one-way ANOVA, p < 0.001) on the Hg concentrations in migratory bird feathers were detected. A risk assessment indicated that approximately 7.0% of individuals were at moderate (2.4-5.0 mg kg-1) to high (>5.0 mg kg-1) risk of Hg exposure, and were therefore vulnerable to adverse physiological and behavioral effects. A long-term monitoring campaign during the migratory period is highly recommended to better understand the bioaccumulation of Hg in these nocturnal migratory bird populations over time.
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Affiliation(s)
- Chan Li
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China
| | - Kang Luo
- 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
| | - Yuxiao Shao
- School of Geography and Environmental Science, Guizhou Normal University, Guiyang, 550001, China
| | - Xiaohang Xu
- 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
| | - Zhuo Chen
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China.
| | - Tao Liang
- Zhenyuan Management and Protection Bureau of Ailao Mountain National Nature Reserve, Zhenyuan, 666500, China
| | - Zhidong Xu
- 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
| | - Xian Dong
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China
| | - Hongdong Wang
- Zhenyuan Management and Protection Bureau of Ailao Mountain National Nature Reserve, Zhenyuan, 666500, China
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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12
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Gfeller L, Caplette JN, Frossard A, Mestrot A. Organo-mercury species in a polluted agricultural flood plain: Combining speciation methods and polymerase chain reaction to investigate pathways of contamination. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 311:119854. [PMID: 35998774 DOI: 10.1016/j.envpol.2022.119854] [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: 04/08/2022] [Revised: 07/16/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Abstract
The analysis of organic mercury (Hg) species in polluted soils is a necessary tool to assess the environmental risk(s) of mercury in contaminated legacy sites. The artificial formation of monomethylmercury (MeHg) during soil extraction and/or analysis is a well-known limitation and is especially relevant in highly polluted areas where MeHg/Hg ratios are notoriously low. Although this has been known for almost 30 years, the thorough characterisation of artificial formation rates is rarely a part of the method development in scientific literature. Here we present the application of two separate procedures (inorganic Hg (iHg) spiking and double-spike isotope dilution analyses (DSIDA)) to determine and correct for artificial Hg methylation in MeHg-selective acid-leaching/organic solvent extraction procedure. Subsequently, we combined corrected MeHg and ethylmercury (EtHg) measurements with PCR amplification of hgcA genes to distinguish between naturally formed MeHg from primary deposited MeHg in soils from a legacy site in a Swiss mountain valley. We found the DSIDA procedure incompatible with the organomercury selective extraction method due to the quantitative removal of iHg. Methylation factors from iHg spiking were in the range of (0.0075 ± 0.0001%) and were consistent across soils and sediment matrices. Further, we suggest that MeHg was deposited and not formed in-situ in two out of three studied locations. Our line of evidence consists of 1) the concomitant detection of EtHg, 2) the elevated MeHg concentrations (up to 4.84 μg kg-1), and 3) the absence of hgcA genes at these locations. The combination of Hg speciation and methylation gene (hgcA) abundance analyses are tools suited to assess Hg pollution pathways at Hg legacy sites.
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Affiliation(s)
- Lorenz Gfeller
- Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern, Switzerland
| | - Jaime N Caplette
- Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern, Switzerland
| | - Aline Frossard
- Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Adrien Mestrot
- Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern, Switzerland.
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13
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Wang Y, Luo Z, Liu D, Li Y. Immobilization of mercury in tailings originating from the historical artisanal and small-scale gold mining using sodium polysulfide. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:56562-56578. [PMID: 35347614 DOI: 10.1007/s11356-022-19569-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
A series of sodium polysulfides (SPSs) with different sulfur indexes was prepared as stabilizers to amend elemental mercury-contaminated artisanal small-scale gold mine (ASGM) tailings in Hubei, China, by controlling the molar ratio of sulfur and sodium sulfides as 1:1, 2:1, 3:1, and 4:1 during the synthesis. XRD, XPS, and laser Raman spectroscopy all suggested that the synthesized SPSs were a mixture of multiple polysulfides, sulfur, sodium sulfides, and sodium thiosulfate. Based on toxicity characteristic leaching procedure test (TCLP), mercury stabilization efficiency of SPSs was evaluated and proved to be more superior than sulfur, sodium sulfide, and also calcium polysulfide, with an optimal stabilization efficiency of 97.16% at SPS/THg = 1:2, SPSs pH = initial pH, and liquid-to-solid ratio = 20:7. A pseudo-second-order kinetic model was able to interpret the stabilization kinetics and demonstrated that mercury stabilization rate increased with the sulfur index in the SPSs, but excess SPSs were potentially to inhibit the precipitation of mercury. Speciation analysis results determined with sequential extraction indicated that the unstable mercury, elemental mercury, and organic-bound mercury fractions decreased respectively by up to 88.6%, 53.5%, and 26.3%. Pearson correlation analysis showed that the mercury stabilization in the mine tailings amended with SPSs mainly occurs from the precipitation of the elemental mercury, and the organic mercury fraction reduction was correlated with the decrease of the unstable mercury.
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Affiliation(s)
- Yu Wang
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China
| | - Zhiqiang Luo
- Yangtze Ecology and Environment Co. Ltd, Wuhan, 430062, China
| | - Danqing Liu
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China.
| | - Yilian Li
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China
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14
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Xiang Y, Zhu A, Guo Y, Liu G, Chen B, He B, Liang Y, Yin Y, Cai Y, Jiang G. Decreased bioavailability of both inorganic mercury and methylmercury in anaerobic sediments by sorption on iron sulfide nanoparticles. JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127399. [PMID: 34638072 DOI: 10.1016/j.jhazmat.2021.127399] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/07/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
Methylmercury (MeHg), derived via inorganic mercury (Hg(II)) methylation by anaerobic microorganisms, is a neurotoxic contaminant causing concern worldwide. Establishing how to reduce Hg(II) methylation and MeHg bioavailability is essential for effective control of Hg pollution. Iron sulfide nanoparticles (FeSNP) is a promising passivator for Hg(II) methylation. However, its effect on the fate of MeHg in aquatic systems remains poorly understood. This study investigated the effect of FeSNP on Hg(II) bioavailability, MeHg production and bioavailability in aquatic environments. Results demonstrated that FeSNP rapidly sorbed Hg(II) and MeHg, with sorption affected by pH, chloride ion and dissolved organic matter. Hg-specific biosensor analysis showed that Hg(II) sorbed onto FeSNP significantly reduced its bioavailability to microorganisms. Double stable isotope (199Hg(II) and Me201Hg) addition revealed that FeSNP significantly inhibited MeHg production in anaerobic sediments. Furthermore, synthetic gut juice extraction suggested that FeSNP decrease concentrations of bioavailable MeHg and Hg(II), reducing their integration into food webs. However, the sorbed MeHg and Hg(II) in sediments can be released after FeSNP oxidation, potentially enhancing the risk of exposure to aquatic organisms. Overall, these findings increase our understanding of Hg transformation and exposure risks in aquatic systems, providing valuable information for the development of in situ Hg remediation systems.
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Affiliation(s)
- Yuping Xiang
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ailing Zhu
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yingying Guo
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Guangliang Liu
- Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA
| | - Baowei Chen
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai 519082, China
| | - Bin He
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Liang
- Institute of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China; Institute of Environment and Health, Jianghan University, Wuhan 430056, China; Institute of Environment and Health, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China.
| | - Yong Cai
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Department of Chemistry & Biochemistry and Southeast Environmental Research Center, Florida International University, 11200 SW 8th ST, Miami, FL 33199, USA
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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15
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Strickman RJ, Larson S, Huang H, Kakouros E, Marvin-DiPasquale M, Mitchell CPJ, Neumann RB. The relative importance of mercury methylation and demethylation in rice paddy soil varies depending on the presence of rice plants. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 230:113143. [PMID: 34998262 DOI: 10.1016/j.ecoenv.2021.113143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/26/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Neurotoxic methylmercury (MeHg) accumulates in rice grain from paddy soil, where its concentration is controlled by microbial mercury methylation and demethylation. Both up- and down-regulation of methylation is known to occur in the presence of rice plants in comparison to non-vegetated paddy soils; the influence of rice plant presence/absence on demethylation is unknown. To assess the concurrent influence of rice plant presence/absence on methylation and demethylation, and to determine which process was more dominant in controlling soil MeHg concentrations, we maintained six rhizoboxes of paddy soil with and without rice plants. At the peak of plant growth, we simultaneously measured ambient MeHg, ambient inorganic mercury (IHg), and potential rate constants of methylation and demethylation (Kmeth and Kdemeth) in soil using stable isotope tracers and ID-GC-ICPMS. We also measured organic matter content, elemental S, and water-extractable sulfate. We found MeHg concentrations were differentially controlled by MeHg production and degradation processes, depending on whether plants were present. In non-vegetated boxes, MeHg concentration was controlled by Kmeth, as evidenced by a strong and positive correlation, while Kdemeth had no relation to MeHg concentration. These results indicate methylation was the dominant driver of MeHg concentration in non-vegetated soil. In vegetated boxes, Kdemeth strongly and negatively predicted MeHg concentration, indicating that demethylation was the dominant control in soil with plants. MeHg concentration, Kmeth, and % MeHg all had significantly less variance in vegetated than in non-vegetated soils due to a consistent elimination of greater values. This pattern suggests that reduced MeHg production capacity was a secondary control on MeHg concentrations in vegetated soils. We observed no difference in the magnitude or variance of Kdemeth between treatments, suggesting that demethylation was robust to soil chemical conditions influenced by the plant, perhaps because of a wider taxonomic diversity of demethylators. Our results suggest that methylation and demethylation processes could both be leveraged to alter MeHg concentrations in rice paddy soil.
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Affiliation(s)
- R J Strickman
- Department of Civil and Environmental Engineering, University of Washington, Seattle, USA.
| | - S Larson
- Department of Civil and Environmental Engineering, University of Washington, Seattle, USA
| | - H Huang
- University of Toronto Scarborough, Ontario, Canada
| | - E Kakouros
- US Geological Survey, Menlo Park, Palo Alto, CA, USA
| | | | | | - R B Neumann
- Department of Civil and Environmental Engineering, University of Washington, Seattle, USA
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16
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Aslam MW, Meng B, Abdelhafiz MA, Liu J, Feng X. Unravelling the interactive effect of soil and atmospheric mercury influencing mercury distribution and accumulation in the soil-rice system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 803:149967. [PMID: 34482140 DOI: 10.1016/j.scitotenv.2021.149967] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
Mercury (Hg) accumulation in rice is an emerging health concern worldwide. However, sources and interactions responsible for Hg species accumulation in different rice tissues are still uncertain. Four experimental plots were carefully designed at an artisanal Hg mining site and a control site to evaluate the effect of atmospheric and soil Hg contents on Hg accumulation in rice. We showed that inorganic Hg (IHg) contents in rice tissues grown either in contaminated or control site soil (non-contaminated soil) were higher at Hg artisanal mining site than those at the control site. Elevated total gaseous mercury (TGM) levels in ambient air were the predominant source of IHg to rice at the Hg mining area. Methylmercury (MeHg) concentrations in rice plant tissues increased in proportionality with MeHg contents in paddy soil. Our results suggest that both atmosphere and soil Hg sources have been impacted the IHg accumulation in rice. Above ground rice tissues, grains, leaves, and stalk accumulated IHg from both atmosphere and soil to varying degrees. Nonetheless, the study also provides the first direct evidence that atmospheric Hg accumulated by above-ground rice tissues could be translocated to below-ground tissues (roots). However, the extent to which atmosphere or soil Hg contributes to IHg in rice tissues may vary with each source's concentration gradient at the given site. No evidence of in planta Hg methylation was found during the current study. Hence, paddy fields are potential MeHg production sites, whereas paddy soil is a unique MeHg accumulation source in rice plants. This study expands and clarifies the contribution of various sources involved in Hg accumulation in the soil rice system. The findings here provide the basis for future research strategies to deal with the global issue of Hg contaminated rice.
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Affiliation(s)
- Muhammad Wajahat Aslam
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China.
| | - Mahmoud A Abdelhafiz
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Geology Department, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China; Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xian 710061, PR China.
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17
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Sánchez-Fortún M, Vinyoles D, López-Carmona S, Carrasco JL, Sanpera C. Effect of different rice farming practices on the bioavailability of mercury: A mesocosm experiment with common goldfish (Carassius auratus). ENVIRONMENTAL RESEARCH 2021; 201:111486. [PMID: 34129865 DOI: 10.1016/j.envres.2021.111486] [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: 12/21/2020] [Revised: 04/30/2021] [Accepted: 06/02/2021] [Indexed: 06/12/2023]
Abstract
Wetlands such as rice paddies are important ecosystems that provide habitat for a numerous range of species but are considered as a major source of mercury in the most toxic form of methylmercury. An in situ mesocosm experiment was conducted during the rice cultivation season of 2018 in rice paddies from the Ebro Delta (NE Spain) to investigate the bioaccumulation of mercury in fish. Common goldfish (Carassius auratus) were exposed to three types of rice-fields subject to different agricultural management (conventional or ecological agriculture) and different hydric practices (wet, dry) and were sampled monthly. Total mercury concentration in fish increased over time for almost all the fields under study, but the mercury increase was particularly higher for fish exposed to ecological fields. We conducted δ15N and δ13C measurements to follow up fish diet changes within or among fields. The results have shown there were no variations in the diet of the fish over time within fields, although differences among management practices were observed, which could explain to some extent the THg variation in fish exposed to each of the agricultural practices. Results indicate that wetting and drying rice fields might be a greater source of mercury for fish and a potential hotspot for MeHg production enhanced by physicochemical parameters. Thus, mercury bioaccumulation in fish inhabiting rice paddies depend on several factors what, in turn, could lead to biomagnification across the food webs.
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Affiliation(s)
- Moisès Sánchez-Fortún
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain.
| | - Dolors Vinyoles
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain
| | - Sophie López-Carmona
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; UFR Sciences et Techniques, Université de Nantes, Nantes, France
| | - Josep Lluís Carrasco
- Biostatistics, Department of Basic Clinical Practice, University of Barcelona, Barcelona, Spain
| | - Carola Sanpera
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain
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18
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Lei P, Tang C, Wang Y, Wu M, Kwong RWM, Jiang T, Zhong H. Understanding the effects of sulfur input on mercury methylation in rice paddy soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 778:146325. [PMID: 33725612 DOI: 10.1016/j.scitotenv.2021.146325] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/18/2021] [Accepted: 03/03/2021] [Indexed: 05/28/2023]
Abstract
Sulfur could be introduced into paddy soils via dry or wet deposition, irrigation, and fertilization, which subsequently impacts the production of methylmercury (MeHg), a bioaccumulative neurotoxicant. However, effects of sulfur input on MeHg production are variable, possibly due to the multiple effects of sulfur on Hg mobility and/or microbial Hg methylators, leading to uncertainties in predicting MeHg risk. To address that, we explored the effects of different types and amounts of sulfur as well as concentrations of ambient sulfate on Hg methylation in paddy soils, and elucidated the mechanisms by quantifying changes in (1) Hg mobility and (2) microbial Hg methylators (e.g., sulfate-reducing bacteria, SRB). Our results indicated that MeHg levels increased by 40-86% and 30-96% in soils under various types (i.e., 200 mg kg-1 elemental sulfur, ammonium sulfate, sulfur-coated urea and potassium sulfate (K2SO4)) and different amounts (i.e., 100, 200 and 400 mg kg-1 K2SO4) of sulfur input. The enhanced MeHg production could be explained by increased Hg mobility but not changes in microbial Hg methylators. Besides, sulfate input increased MeHg levels (89-240%) in soils with low ambient sulfate levels (<100 mg kg-1) but had no effect on high-sulfate soils (>380 mg kg-1). These could be explained by the diverse responses of Hg mobility and microbial Hg methylators to sulfate input at different ambient sulfate levels. Our study opens the "black box" of Hg methylation under sulfur input, which would help reduce uncertainties in predicting MeHg risk in soils.
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Affiliation(s)
- Pei Lei
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Chao Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Yongjie Wang
- School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - MengJie Wu
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | | | - Tao Jiang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden
| | - 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, Canada.
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19
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Wang Y, Sun Y, He T, Deng H, Wang Z, Wang J, Zheng X, Zhou L, Zhong H. Biochar amendment mitigates the health risks of dietary methylmercury exposure from rice consumption in mercury-contaminated areas. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115547. [PMID: 33254602 DOI: 10.1016/j.envpol.2020.115547] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/23/2020] [Accepted: 08/25/2020] [Indexed: 06/12/2023]
Abstract
The accumulation of methylmercury (MeHg) in rice is an important MeHg exposure pathway in humans in several mercury (Hg)-contaminated areas. In this study, the effects of low-dose biochar (BC) amendment (0.3%, w/w) on MeHg mobility/phytoavailability in different Hg-contaminated paddy soils, MeHg accumulation in rice plants and the health risks associated with MeHg-laden rice consumption were investigated. Soils amended with different doses of bamboo-derived BC (0.3, 0.5, and 1%, w/w) were incubated under anoxic conditions in microcosm experiments. In addition, pot experiments were conducted involving rice cultivation with a low BC application rate (0.3%, w/w). We observed that (1) the fraction of extractable MeHg in soils decreased with BC addition in both the microcosm and pot experiments; (2) MeHg concentrations in the rice grains (brown rice) significantly decreased by 56-88% in response to BC amendment, which may be attributed mainly to decreases in MeHg mobility/phytoavailability in the soil; and (3) the hazard quotient (HQ) values for adults and children and fetal intelligence quotient (IQ) decrements associated with MeHg-laden rice consumption were significantly alleviated under BC amendment. Taken together, our findings suggest that a low dose of BC (0.3%, w/w) could have great potential for mitigating the health risks of dietary MeHg exposure from the consumption of rice grown in mercury (Hg)-contaminated areas.
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Affiliation(s)
- Yongjie Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Yafei Sun
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Tianrong He
- Key Laboratory of Karst Environment and Geohazard Prevention, Guizhou University, Guiyang, 550003, PR China
| | - Hong Deng
- Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China; Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Technology Innovation Center for Land Spatial Eco-restoration in Metropolitan area, Ministry of Natural Resource, School of Ecological and Environmental Science, East China Normal University, Shanghai, 200241, PR China
| | - Zhigang Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Jiangtao Wang
- Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Xiangmin Zheng
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Limin Zhou
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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20
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Wang AO, Ptacek CJ, Paktunc D, Mack EE, Blowes DW. Application of biochar prepared from ethanol refinery by-products for Hg stabilization in floodplain soil: Impacts of drying and rewetting. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115396. [PMID: 32882459 DOI: 10.1016/j.envpol.2020.115396] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
This study evaluated three biochars derived from bioenergy by-products - manure-based anaerobic digestate (DIG), distillers' grains (DIS), and a mixture thereof (75G25S) - as amendments to stabilize Hg in contaminated floodplain soil under long-term saturated (up to 200 d) and cyclic drying and rewetting conditions. Greater total Hg (THg) removal (72 to nearly 100%) and limited MeHg production (<65 ng L-1) were observed in digestate-based biochar-amended systems under initial saturated conditions. Drying and rewetting resulted in limited THg release, increased aqueous MeHg, and decreased solid MeHg in digestate-based biochar-amended systems. Changes in Fe and S chemistry as well as microbial communities during drying and rewetting potentially affected MeHg production. Digestate-based biochars may be more effective as amendments to control Hg release and minimize MeHg production in floodplain soils under long-term saturated and drying and rewetting conditions compared to distillers' grains biochar.
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Affiliation(s)
- Alana O Wang
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada
| | - Carol J Ptacek
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada.
| | - Dogan Paktunc
- CanmetMINING, Natural Resource Canada, Ottawa, ON, K1A 0G1, Canada
| | - E Erin Mack
- Formerly E. I. du Pont de Nemours and Company, 974 Centre Road, Wilmington, DE, 19805, USA
| | - David W Blowes
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada
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21
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Qin C, Du B, Yin R, Meng B, Fu X, Li P, Zhang L, Feng X. Isotopic Fractionation and Source Appointment of Methylmercury and Inorganic Mercury in a Paddy Ecosystem. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14334-14342. [PMID: 33112617 DOI: 10.1021/acs.est.0c03341] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Bioaccumulation of methylmercury (MeHg) in rice grains has been an emerging issue of human health, but the mechanism of bioaccumulation is still poorly understood. Mercury (Hg) isotope measurements are powerful tools for tracing the sources and biogeochemical cycles of Hg in the environment. In this study, MeHg compound-specific stable isotope analysis (CSIA) was developed in paddy soil and rice plants to trace the biogeochemical cycle of Hg in a paddy ecosystem during the whole rice-growing season. Isotopic fractionation was analyzed separately for MeHg and inorganic Hg (IHg). Results showed distinct isotopic signals between MeHg and IHg in rice plants, indicating different sources. δ202Hg values of MeHg showed no significant differences between roots, stalks, leaves, and grains at each growth stage. The similar Δ199Hg values of MeHg between rice tissues (0.14 ± 0.08‰, 2SD, n = 12), soil (0.13 ± 0.03‰, 2SD, n = 4), and irrigation water (0.17 ± 0.09‰, 2SD, n = 5) suggested that the soil-water system was the original source of MeHg in rice plants. Δ199Hg values of IHg in the paddy ecosystem indicated that water, soil, and atmosphere contributed to IHg in grains, leaves, stalks, and roots with varying degree. This study demonstrates that successful application of MeHg CSIA can improve our understanding of the sources and bioaccumulation mechanisms of MeHg and IHg in the paddy ecosystems.
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Affiliation(s)
- Chongyang Qin
- 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
| | - Buyun Du
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
| | - Leiming Zhang
- Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto M3H 5T4, Canada
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
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22
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Wu Q, Hu H, Meng B, Wang B, Poulain AJ, Zhang H, Liu J, Bravo AG, Bishop K, Bertilsson S, Feng X. Methanogenesis Is an Important Process in Controlling MeHg Concentration in Rice Paddy Soils Affected by Mining Activities. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:13517-13526. [PMID: 33084323 DOI: 10.1021/acs.est.0c00268] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Rice paddies are agricultural sites of special concern because the potent toxin methylmercury (MeHg), produced in rice paddy soils, accumulates in rice grains. MeHg cycling is mostly controlled by microbes but their importance in MeHg production and degradation in paddy soils and across a Hg concentration gradient remains unclear. Here we used surface and rhizosphere soil samples in a series of incubation experiments in combination with stable isotope tracers to investigate the relative importance of different microbial groups on MeHg production and degradation across a Hg contamination gradient. We showed that sulfate reduction was the main driver of MeHg formation and concentration at control sites, and that methanogenesis had an important and complex role in MeHg cycling as Hg concentrations increased. The inhibition of methanogenesis at the mining sites led to an increase in MeHg production up to 16.6-fold and a decrease in MeHg degradation by up to 77%, suggesting that methanogenesis is associated with MeHg degradation as Hg concentrations increased. This study broadens our understanding of the roles of microbes in MeHg cycling and highlights methanogenesis as a key control of MeHg concentrations in rice paddies, offering the potential for mitigation of Hg contamination and for the safe production of rice in Hg-contaminated areas.
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Affiliation(s)
- Qingqing Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Haiyan Hu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
| | - Baolin Wang
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
| | - Alexandre J Poulain
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
| | - Hua Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
| | - Jinling Liu
- School of Earth Sciences, China University of Geosciences, Wuhan 430074, P. R. China
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Pg Marítim de la Barceloneta 37-49, Barcelona E08003, Catalunya, Spain
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, P. R. China
- Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xian 710061, P. R. China
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23
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Tang Z, Fan F, Deng S, Wang D. Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 202:110950. [PMID: 32800226 DOI: 10.1016/j.ecoenv.2020.110950] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.
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Affiliation(s)
- Zhenya Tang
- Faculty of Environmental Science & Engineering, Kunming University of Science &Technology, Kunming, China; Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China.
| | - Fangling Fan
- School of Energy and Environment Science, Yunnan Normal University, Kunming, China.
| | - Shiping Deng
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK, USA.
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China; State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing, China.
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24
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Shanley JB, Marvin-DiPasquale M, Lane O, Arendt W, Hall S, McDowell WH. Resolving a paradox-high mercury deposition, but low bioaccumulation in northeastern Puerto Rico. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1207-1220. [PMID: 31643013 DOI: 10.1007/s10646-019-02108-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
At a "clean air" trade winds site in northeastern Puerto Rico, we found an apparent paradox: atmospheric total mercury (THg) deposition was highest of any site in the USA Mercury Deposition Network, but assimilation into the local food web was quite low. Avian blood THg concentrations (n = 31, from eight species in five foraging guilds) ranged widely from 0.2 to 32 ng g-1 (median of 4.3 ng g-1). Within this population, THg was significantly greater at a low-elevation site near a wetland compared to an upland montane site, even when the comparison was limited to a single species. Overall, however, THg concentrations were approximately an order of magnitude lower than comparable populations in the continental U.S. In surface soil and sediment, potential rates of demethylation were 3 to 9-fold greater than those for Hg(II)-methylation (based on six radiotracer amendment incubations), but rates of change of ambient MeHg pools showed a slight net positive Hg(II)-methylation. Thus, the resolution of the paradox is that MeHg degradation approximately keeps pace with MeHg production in this landscape. Further, any net production of MeHg is subject to frequent flushing by high rainfall on chronically wet soils. The interplay of these microbial processes and hydrology appears to shield the local food web from adverse effects of high atmospheric mercury loading. This scenario may play out in other humid tropical ecosystems as well, but it is difficult to evaluate because coordinated studies of Hg deposition, methylation, and trophic uptake have not been conducted at other tropical sites.
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Affiliation(s)
- James B Shanley
- U.S. Geological Survey, P.O. Box 628, Montpelier, VT, 05601, USA.
| | | | - Oksana Lane
- Biodiversity Research Institute, Portland, ME, USA
| | - Wayne Arendt
- USFS, International Institute of Tropical Forestry, Luquillo, PR, USA
| | - Steven Hall
- Department of Ecology and Evolutionary Biology, Iowa State University, Ames, IA, USA
| | - William H McDowell
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA
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25
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Bishop K, Shanley JB, Riscassi A, de Wit HA, Eklöf K, Meng B, Mitchell C, Osterwalder S, Schuster PF, Webster J, Zhu W. Recent advances in understanding and measurement of mercury in the environment: Terrestrial Hg cycling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 721:137647. [PMID: 32197286 DOI: 10.1016/j.scitotenv.2020.137647] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 02/23/2020] [Accepted: 02/28/2020] [Indexed: 06/10/2023]
Abstract
This review documents recent advances in terrestrial mercury cycling. Terrestrial mercury (Hg) research has matured in some areas, and is developing rapidly in others. We summarize the state of the science circa 2010 as a starting point, and then present the advances during the last decade in three areas: land use, sulfate deposition, and climate change. The advances are presented in the framework of three Hg "gateways" to the terrestrial environment: inputs from the atmosphere, uptake in food, and runoff with surface water. Among the most notable advances: These and other advances reported here are of value in evaluating the effectiveness of the Minamata Convention on reducing environmental Hg exposure to humans and wildlife.
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Affiliation(s)
- Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
| | | | - Ami Riscassi
- Department of Environmental Sciences, University of Virginia, P.O. Box 400123, Charlottesville, VA 22904-4123, USA.
| | - Heleen A de Wit
- Norwegian Institute for Water Research, Gaustadalléen 21, NO-0349, Norway.
| | - Karin Eklöf
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
| | - Carl Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
| | - Stefan Osterwalder
- Institut des Géosciences de l'Environnement, Université Grenoble Alpes, CNRS, IRD, Grenoble 18 INP, 38000 Grenoble, France.
| | - Paul F Schuster
- U.S. Geological Survey, 3215 Marine Street, Suite E-127, Boulder, CO 80303-1066, USA.
| | - Jackson Webster
- Department of Civil Engineering, California State University, 400 W. 1st Street, 21 95929-0930 Chico, CA, USA.
| | - Wei Zhu
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
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26
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Zhao L, Meng B, Feng X. Mercury methylation in rice paddy and accumulation in rice plant: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110462. [PMID: 32179234 DOI: 10.1016/j.ecoenv.2020.110462] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/07/2020] [Accepted: 03/08/2020] [Indexed: 06/10/2023]
Abstract
The bioavailability and toxicity of mercury (Hg) are dependent on its chemical speciation, in which methylmercury (MeHg) is the most toxic compound. Inorganic Hg can be transformed into MeHg in anaerobic conditions. Subsequent accumulation and biomagnification in the food chain pose a potential threat to human health. Previous studies have confirmed that paddy soil is an important site for MeHg production, and rice fields are an important source of MeHg in terrestrial ecosystems. Rice (Oryza sativa L.) is recently confirmed as a potential bioaccumulator plant of MeHg. Understanding the behaviour of Hg in rice paddies is important, particularly the mechanisms involved in Hg sources, uptake, toxicity, detoxification, and accumulation in crops. This review highlights the issue of MeHg-contaminated rice, and presents the current understanding of the Hg cycling in the rice paddy ecosystem, including the mechanism and processes of Hg species accumulation in rice plants and Hg methylation/demethylation processes in rice paddies and the primary controlling factors. The review also identified various research gaps in previous studies and proposes future research objectives to reduce the impact of Hg-contamination in rice crops.
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Affiliation(s)
- Lei Zhao
- School of Management Science, Guizhou University of Finance and Economics, Guiyang, 550025, PR China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China.
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27
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Li Y, He X, Wang Y, Guan J, Guo J, Xu B, Chen YH, Wang G. Organic fertilizer amendment increases methylmercury accumulation in rice plants. CHEMOSPHERE 2020; 249:126166. [PMID: 32062560 DOI: 10.1016/j.chemosphere.2020.126166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/05/2020] [Accepted: 02/08/2020] [Indexed: 06/10/2023]
Abstract
Rice grains are a methylmercury (MeHg) intake route for humans, especially in certain mercury (Hg)-contaminated areas. For rice plant growth, animal manure is commonly used as an organic fertilizer; however, its role in the formation of MeHg in paddy soils remains poorly understood. The aims of this study were thus to explore 1) the effect of chicken manure (CH) and cow manure (CO) addition on the production of soil MeHg and the accumulation of MeHg in rice plants and 2) the mechanism by which CH and CO addition affect the bioaccumulation of MeHg in grains. A pot experiment with different levels of CH and CO was carried out with newly deposited Hg-contaminated paddy soil. Two microcosm experiments were performed to explore the associated mechanisms. The results of the pot experiment showed that 0.1-1% CH and CO addition promoted the biomass of rice plants by 10-23% and increased the soil MeHg concentration by 34-143%, which exhibited a significant positive correlation with brown rice MeHg content. Organic fertilizer addition significantly increased MeHg bioaccumulation in rice plants and the ratio of MeHg to total Hg (THg) in brown rice. Organic fertilizer also increased the abundance of microbial methylators. The results of the microcosm experiments showed that organic fertilizer addition enhanced dissolved THg concentrations in soil and consequently increased the soil MeHg concentration. These results suggested that applying organic fertilizer to newly deposited Hg-contaminated soil may increase MeHg accumulation in grains due to enhanced Hg release and microbial methylator activity, leading to environmental health concerns.
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Affiliation(s)
- Yunyun Li
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Xucheng He
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Yongjie Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China
| | - Jiaxun Guan
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jingxia Guo
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Bo Xu
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Yan-Hui Chen
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Guo Wang
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
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28
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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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29
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Eckley CS, Gilmour CC, Janssen S, Luxton TP, Randall PM, Whalin L, Austin C. The assessment and remediation of mercury contaminated sites: A review of current approaches. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 707:136031. [PMID: 31869604 PMCID: PMC6980986 DOI: 10.1016/j.scitotenv.2019.136031] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/07/2019] [Accepted: 12/07/2019] [Indexed: 04/13/2023]
Abstract
Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial extent of contamination, Hg stable isotope fractionation to identify sources and transformation processes, and solid-phase characterization (XAFS) to evaluate Hg forms. The understanding of Hg bioavailability for methylation has been improved by methods such as sequential chemical extractions and porewater measurements, including the use of diffuse gradient in thin-film (DGT) samplers. These approaches have shown varying success in identifying bioavailable Hg fractions and further study and field applications are needed. The downstream accumulation of methylmercury (MeHg) in biota is a concern at many contaminated sites. Identifying the variables limiting/controlling MeHg production-such as bioavailable inorganic Hg, organic carbon, and/or terminal electron acceptors (e.g. sulfate, iron) is critical. Mercury can be released from contaminated sites to the air and water, both of which are influenced by meteorological and hydrological conditions. Mercury mobilized from contaminated sites is predominantly bound to particles, highly correlated with total sediment solids (TSS), and elevated during stormflow. Remediation techniques to address Hg contamination can include the removal or containment of Hg contaminated materials, the application of amendments to reduce mobility and bioavailability, landscape/waterbody manipulations to reduce MeHg production, and food web manipulations through stocking or extirpation to reduce MeHg accumulated in desired species. These approaches often rely on knowledge of the Hg forms/speciation at the site, and utilize physical, chemical, thermal and biological methods to achieve remediation goals. Overall, the complexity of Hg cycling allows many different opportunities to reduce/mitigate impacts, which creates flexibility in determining suitable and logistically feasible remedies.
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Affiliation(s)
- Chris S Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101, USA.
| | - Cynthia C Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 21037-0028, USA.
| | - Sarah Janssen
- USGS Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA.
| | - Todd P Luxton
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Paul M Randall
- US Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA.
| | - Lindsay Whalin
- San Francisco Bay Water Board, 1515 Clay St., Ste. 1400, Oakland, CA 94612, USA.
| | - Carrie Austin
- San Francisco Bay Water Board, 1515 Clay St., Ste. 1400, Oakland, CA 94612, USA.
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30
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Hall LA, Woo I, Marvin-DiPasquale M, Tsao DC, Krabbenhoft DP, Takekawa JY, De La Cruz SEW. Disentangling the effects of habitat biogeochemistry, food web structure, and diet composition on mercury bioaccumulation in a wetland bird. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 256:113280. [PMID: 31718826 DOI: 10.1016/j.envpol.2019.113280] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/29/2019] [Accepted: 09/18/2019] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) is a globally pervasive contaminant with known toxicity to humans and wildlife. Several sources of variation can lead to spatial differences in MeHg bioaccumulation within a species including: biogeochemical processes that influence MeHg production and availability within an organism's home range; trophic positions of consumers and MeHg biomagnification efficiency in food webs; and individual prey preferences that influence diet composition. To better understand spatial variation in MeHg bioaccumulation within a species, we evaluated the effects of habitat biogeochemistry, food web structure, and diet composition in the wetland-obligate California black rail (Laterallus jamaicensis coturniculus) at three wetlands along the Petaluma River in northern San Francisco Bay, California, USA. The concentration of MeHg in sediments differed significantly among wetlands. We identified three sediment and porewater measurements that contributed significantly to a discriminant function explaining differences in habitat biogeochemistry among wetlands: the porewater concentration of ferrous iron, the percent organic matter, and the sediment MeHg concentration. Food web structure and biomagnification efficiency were similar among wetlands, with trophic magnification factors for MeHg ranging from 1.84 to 2.59. In addition, regurgitation samples indicated that black rails were dietary generalists with similar diets among wetlands (percent similarity indices > 70%). Given the similarities in diet composition, food web structure, and MeHg biomagnification efficiency among wetlands, we concluded that variation in habitat biogeochemistry and associated sediment MeHg production was the primary driver of differences in MeHg concentrations among black rails from different wetlands.
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Affiliation(s)
- Laurie A Hall
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, PO Box 158, Moffett Field, CA 94035, USA.
| | - Isa Woo
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, PO Box 158, Moffett Field, CA 94035, USA
| | - Mark Marvin-DiPasquale
- U.S. Geological Survey, Biogeochemistry Laboratory, 345 Middlefield Road, Menlo Park, CA 94025, USA
| | - Danika C Tsao
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, PO Box 158, Moffett Field, CA 94035, USA
| | - David P Krabbenhoft
- U.S. Geological Survey, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - John Y Takekawa
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, PO Box 158, Moffett Field, CA 94035, USA
| | - Susan E W De La Cruz
- U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, PO Box 158, Moffett Field, CA 94035, USA
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Xu X, Han J, Abeysinghe KS, Atapattu AJ, De Silva PMCS, Xu Z, Long S, Qiu G. Dietary exposure assessment of total mercury and methylmercury in commercial rice in Sri Lanka. CHEMOSPHERE 2020; 239:124749. [PMID: 31505443 DOI: 10.1016/j.chemosphere.2019.124749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Revised: 08/28/2019] [Accepted: 09/03/2019] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) in rice has attracted growing health concern over the past decade, due to the accumulation of high MeHg levels, which may pose potential health risk to humans. Rice is the staple food in Sri Lanka; nevertheless, the presence of micro pollutants, such as MeHg has been not investigated. Therefore, commercial rice samples from the Sri Lankan market (n = 163) were measured to reveal the total mercury (THg) and MeHg levels. THg (mean: 1.73 ± 0.89 ng/g, range: 0.21-6.13 ng/g) and MeHg concentrations (mean: 0.51 ± 0.37 ng/g; range: 0.03-3.81 ng/g) were low. Compared to the fish MeHg exposure, the rice MeHg exposure was generally lower in different consumption groups, suggesting that rice plays a less role than fish in MeHg exposure in Sri Lanka. Babies (infants and toddlers) at one year old may face fish MeHg exposure (0.17 μg/kg bw/day) higher than the reference dose for MeHg (RfD)-0.1 μg/kg bw/day, which was more than 5 times that of rice MeHg exposure (0.031 μg/kg bw/day). Future studies in Sri Lanka should focus on health impacts under long-term overexposure of MeHg, especially in vulnerable populations. Some diet changes should be made to mitigate MeHg exposure levels in Sri Lankans.
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Affiliation(s)
- Xiaohang Xu
- 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
| | - Jialiang Han
- 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
| | - Kasun S Abeysinghe
- 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
| | - Anjana J Atapattu
- University of Chinese Academy of Sciences, Beijing, 100049, China; Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China; Agronomy Division, Coconut Research Institute, Lunuwila, 61150, Sri Lanka
| | | | - Zhidong Xu
- 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
| | | | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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32
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Ao M, Xu X, Wu Y, Zhang C, Meng B, Shang L, Liang L, Qiu R, Wang S, Qian X, Zhao L, Qiu G. Newly deposited atmospheric mercury in a simulated rice ecosystem in an active mercury mining region: High loading, accumulation, and availability. CHEMOSPHERE 2020; 238:124630. [PMID: 31473530 DOI: 10.1016/j.chemosphere.2019.124630] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 08/17/2019] [Accepted: 08/20/2019] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) mining activities are an important anthropogenic source of atmospheric Hg. The Xunyang Hg mine located in Shaanxi Province is the largest active Hg producing centre in China. To understand the biogeochemical processes of atmospheric Hg through Hg mining activities, six groups of experimental pots were carefully designed to investigate the effect of Hg mining activities on Hg contamination from atmospheric deposition in the local surface soils. Based on the variations of Hg in the soil from the experimental pots, the deposition flux and loading of Hg in the Xunyang Hg mining district were investigated. The results showed that the average concentration of total gaseous mercury (TGM) as high as 193 ± 122 ng m-3 was observed in the ambient air, which was orders of magnitude higher than that in remote areas. The average deposition flux and annual loading of atmospheric Hg were 72 mg m-2 y-1 and 10 t y-1, respectively. The dominant atmospheric Hg deposition is within a distance range of 6.0-12 km from the Hg retorting facility, accounting for approximately 85% of the total Hg loading. After 14 months of exposure, total mercury (THg) concentrations in the soil from the experimental pots increased 0.35-9.5 times, and the highest concentrations of methylmercury (MeHg) (3.7 ± 2.9 μg kg-1) in soil were observed in February. Concentrations as high as 643 μg kg-1 THg and 13 μg kg-1 MeHg in rice were observed in the second experimental year. Elevated concentrations of both THg and MeHg in rice indicated that the newly deposited atmospheric Hg was bioavailable, readily methylated, and taken up by rice, suggesting that the ongoing Hg mining activities cause serious Hg contamination in the soil-rice ecosystem and posed a threat to local residents in the Xunyang Hg mining area.
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Affiliation(s)
- Ming Ao
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, PR China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, PR China
| | - Xiaohang Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Yonggui Wu
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, PR China.
| | - Chao Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China
| | - Lihai Shang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China
| | - Longchao Liang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, PR China
| | - Rongliang Qiu
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, PR China
| | - Shizhong Wang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, PR China
| | - Xiaoli Qian
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, PR China
| | - Lei Zhao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academic of Sciences, Guiyang, 550081, PR China.
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Wang Y, Chen Z, Wu Y, Zhong H. Comparison of methylmercury accumulation in wheat and rice grown in straw-amended paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 697:134143. [PMID: 31476499 DOI: 10.1016/j.scitotenv.2019.134143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/16/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Paddy soil is a key area of methylmercury (MeHg) production and is dominated by fluctuating redox conditions following rice plant growth or rice-wheat rotation planting in eastern and southern Asia. The role of organic matter in the formation of MeHg under these biogeochemical redox cycles remains poorly understood, especially in certain mercury (Hg)-contaminated paddy soils. Here, we provide a detailed understanding of the formation of MeHg and its accumulation in crops (i.e., wheat and rice) in rice-wheat rotation systems under straw return. Two series of experiments, pot and microcosm experiments, were performed using Hg-contaminated paddy soil with 1% (w/w) wheat or rice straw addition under aerobic or anoxic conditions. The results showed that straw amendments increased MeHg levels in wheat (by 225%) and rice (by 20%) grains, most likely due to the elevated soil MeHg following straw amendment. Microcosm experiments further confirmed that fresh straw-derived organic matter enhances MeHg net production in soil through an overall increase in the activity of sulfate-reducing bacteria (SRB), particularly under anoxic conditions. Our study clearly demonstrated that straw amendment enhanced MeHg accumulation in wheat and rice grains and highlighted that straw return in Hg-contaminated soils may increase the health risk of MeHg exposure to local residents via crop consumption. Thus, some guidance should be provided for crop residue return in rice-wheat rotation system farming practices.
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Affiliation(s)
- Yongjie Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China
| | - Zongya Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550002, PR China
| | - Yonggui Wu
- College of Resources and Environmental Engineering, Guizhou University, Guiyang 550002, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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Li Y, Hu W, Zhao J, Chen Q, Wang W, Li B, Li YF. Selenium decreases methylmercury and increases nutritional elements in rice growing in mercury-contaminated farmland. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 182:109447. [PMID: 31325809 DOI: 10.1016/j.ecoenv.2019.109447] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/04/2019] [Accepted: 07/13/2019] [Indexed: 05/09/2023]
Abstract
Methylmercury (MeHg) in rice grains grown in Hg-contaminated areas has raised environmental health concerns. Pot experiments found that selenium (Se) could reduce MeHg levels in rice grains. However, relatively high levels of Se (up to 6 mg/kg) were applied in these pot experiments, which may have adverse effects on the soil ecology due to the toxicity of Se. The aims of this work were thus to study 1) the effect of low levels of Se on the accumulation and distribution of Hg, especially MeHg, in rice plants grown in a real Hg-contaminated paddy field and 2) the effect of Se treatment on Se and other nutritional elements (e.g., Cu, Fe, Zn) in grains. A field study amended with different levels of Se was carried out in Hg-contaminated paddy soil in Qingzhen, Guizhou, China. The levels of MeHg and total Hg were studied using cold vapor atomic fluorescence spectrometry (CVAFS) and inductively coupled plasma mass spectrometry (ICP-MS). The distribution and relative quantification of elements in grains were examined by synchrotron radiation X-ray fluorescence analysis (SR-XRF). This field study showed that low levels of Se (0.5 μg/mL, corresponding to 0.15 mg Se/kg soils) could significantly reduce total Hg and MeHg in rice tissues. Se treatment also reduced Hg distribution in the embryo and endosperm and increased the levels of Fe, Cu, Zn and Se in grains and especially embryos. This field study implied that treatment with an appropriate level of Se is an effective approach to not only decrease the level of MeHg but to also increase the levels of nutritional elements such as Fe, Cu, Zn and Se in rice grains, which could bring beneficial effects for rice-dependent residents living in Hg-contaminated areas.
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Affiliation(s)
- Yunyun Li
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China; CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, And HKU-IHEP Joint Laboratory on Metallomics, And State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Wenjun Hu
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, And HKU-IHEP Joint Laboratory on Metallomics, And State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Qimin Chen
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Wei Wang
- College of Engineering, China Agricultural University, Beijing, 100083, China.
| | - Bai Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, And HKU-IHEP Joint Laboratory on Metallomics, And State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu-Feng Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, And HKU-IHEP Joint Laboratory on Metallomics, And State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
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35
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Tang W, Hintelmann H, Gu B, Feng X, Liu Y, Gao Y, Zhao J, Zhu H, Lei P, Zhong H. Increased Methylmercury Accumulation in Rice after Straw Amendment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6144-6153. [PMID: 30983351 DOI: 10.1021/acs.est.8b07145] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Consumption of rice has been shown to be an important route of dietary exposure to methylmercury (MeHg, a neurotoxin) for Asians having a low fish but high rice diet. Therefore, factors that increase MeHg production and bioaccumulation in soil-rice systems, could enhance the risk of MeHg exposure. On the basis of a national-scale survey in China (64 sites in 12 provinces) and rice cultivation experiments, we report that straw amendment, a globally prevalent farming practice, could increase MeHg concentrations in paddy soils (11-1043%) and rice grains (95%). By carrying out a series of batch incubation, seedling uptake and sand culture experiments, we demonstrate that these increases could be attributed to (1) enhanced abundances/activities of microbial methylators and the transformation of refractory HgS to organic matter-complexed Hg, facilitating microbial Hg methylation in soils; (2) enhanced MeHg mobility, and increased root lengths (35-41%) and tip numbers (60-105%), increasing MeHg uptake by rice roots; and (3) enhanced MeHg translocation to rice grains from other tissues. Results of this study emphasize fresh organic matter-enhanced MeHg production and bioaccumulation, and highlight the increased risk of MeHg after straw amendment and thus the need for new policies concerning straw management.
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Affiliation(s)
- Wenli Tang
- School of the Environment , Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse , Nanjing , Jiangsu Province 210023 , P. R. China
| | - Holger Hintelmann
- Department of Chemistry , Trent University , Peterborough , Ontario K9L 0G2 , Canada
| | - Baohua Gu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37830 , United States
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry , Institute of Geochemistry, Chinese Academy of Sciences , Guiyang , Guizhou Province 550081 , P. R. China
| | - Yurong Liu
- College of Resources and Environment , Huazhong Agricultural University , Wuhan , Hubei Province 430070 , P. R. China
| | - Yuxi Gao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, and Laboratory of Metallomics and Nanometallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Jiating Zhao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, and Laboratory of Metallomics and Nanometallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Huike Zhu
- School of the Environment , Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse , Nanjing , Jiangsu Province 210023 , P. R. China
| | - Pei Lei
- Institute for Advanced Study , Shenzhen University , Shenzhen , Guangdong Province 518060 , P. R. China
| | - Huan Zhong
- School of the Environment , Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse , Nanjing , Jiangsu Province 210023 , P. R. China
- Environmental and Life Sciences Program (EnLS) , Trent University , Peterborough , Ontario K9L 0G2 , Canada
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Beckers F, Awad YM, Beiyuan J, Abrigata J, Mothes S, Tsang DCW, Ok YS, Rinklebe J. Impact of biochar on mobilization, methylation, and ethylation of mercury under dynamic redox conditions in a contaminated floodplain soil. ENVIRONMENT INTERNATIONAL 2019; 127:276-290. [PMID: 30951944 DOI: 10.1016/j.envint.2019.03.040] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/14/2019] [Accepted: 03/14/2019] [Indexed: 06/09/2023]
Abstract
Mercury (Hg) is a highly toxic element, which is frequently enriched in flooded soils due to its anthropogenic release. The mobilization of Hg and its species is of ultimate importance since it controls the transfer into the groundwater and plants and finally ends in the food chain, which has large implications on human health. Therefore, the remediation of those contaminated sites is an urgent need to protect humans and the environment. Often, the stabilization of Hg using amendments is a reliable option and biochar is considered a candidate to fulfill this purpose. We tested two different pine cone biochars pyrolyzed at 200 °C or 500 °C, respectively, with a view to decrease the mobilization of total Hg (Hgt), methylmercury (MeHg), and ethylmercury (EtHg) and/or the formation of MeHg and EtHg in a contaminated floodplain soil (Hgt: 41 mg/kg). We used a highly sophisticated automated biogeochemical microcosm setup to systematically alter the redox conditions from ~-150 to 300 mV. We continuously monitored the redox potential (EH) along with pH and determined dissolved organic carbon (DOC), SUVA254, chloride (Cl-), sulfate (SO42-), iron (Fe), and manganese (Mn) to be able to explain the mobilization of Hg and its species. However, the impact of biochar addition on Hg mobilization was limited. We did not observe a significant decrease of Hgt, MeHg, and EtHg concentrations after treating the soil with the different biochars, presumably because potential binding sites for Hg were occupied by other ions and/or blocked by biofilm. Solubilization of Hg bound to DOC upon flooding of the soils might have occurred which could be an indirect impact of EH on Hg mobilization. Nevertheless, Hgt, MeHg, and EtHg in the slurry fluctuated between 0.9 and 52.0 μg/l, 11.1 to 406.0 ng/l, and 2.3 to 20.8 ng/l, respectively, under dynamic redox conditions. Total Hg concentrations were inversely related to the EH; however, ethylation of Hg was favored at an EH around 0 mV while methylation was enhanced between -50 and 100 mV. Phospholipid fatty acid profiles suggest that sulfate-reducing bacteria may have been the principal methylators in our experiment. In future, various biochars should be tested to evaluate their potential in decreasing the mobilization of Hg and to impede the formation of MeHg and EtHg under dynamic redox conditions in frequently flooded soils.
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Affiliation(s)
- Felix Beckers
- University of Wuppertal, Institute of Foundation Engineering, Waste and Water Management, School of Architecture and Civil Engineering, Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
| | - Yasser Mahmoud Awad
- University of Wuppertal, Institute of Foundation Engineering, Waste and Water Management, School of Architecture and Civil Engineering, Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; Korea Biochar Research Center, O-Jeong Eco-Resilience Institute (OJERI) & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea; Faculty of Agriculture, Suez Canal University, Ismailia 41522, Egypt
| | - Jingzi Beiyuan
- University of Wuppertal, Institute of Foundation Engineering, Waste and Water Management, School of Architecture and Civil Engineering, Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; School of Environment and Chemical Engineering, Foshan University, Foshan, Guangdong, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Jens Abrigata
- University of Wuppertal, Institute of Foundation Engineering, Waste and Water Management, School of Architecture and Civil Engineering, Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
| | - Sibylle Mothes
- UFZ Helmholtz Centre for Environmental Research, Department of Analytical Chemistry, Permoserstraße 15, 04318 Leipzig, Germany
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Yong Sik Ok
- Korea Biochar Research Center, O-Jeong Eco-Resilience Institute (OJERI) & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
| | - Jörg Rinklebe
- University of Wuppertal, Institute of Foundation Engineering, Waste and Water Management, School of Architecture and Civil Engineering, Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; Department of Environment, Energy & Geoinformatics, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, Republic of Korea.
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He M, Tian L, Braaten HFV, Wu Q, Luo J, Cai LM, Meng JH, Lin Y. Mercury-Organic Matter Interactions in Soils and Sediments: Angel or Devil? BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:621-627. [PMID: 30600387 DOI: 10.1007/s00128-018-2523-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
Many studies have suggested that organic matter (OM) substantially reduces the bioavailability and risks of mercury (Hg) in soils and sediments; however, recent reports have supported that OM greatly accelerates Hg methylation and increases the risks of Hg exposure. This study aims to summarize the interactions between Hg and OM in soils and sediments and improve our understanding of the effects of OM on Hg methylation. The results show that OM characteristics, promotion of the activity of Hg-methylating microbial communities, and the microbial availability of Hg accounted for the acceleration of Hg methylation which increases the risk of Hg exposure. These three key aspects were driven by multiple factors, including the types and content of OM, Hg speciation, desorption and dissolution kinetics and environmental conditions.
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Affiliation(s)
- Mei He
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Lei Tian
- School of Petroleum Engineering, Yangtze University, Wuhan, 430100, People's Republic of China
| | | | - Qingru Wu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Jie Luo
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Li-Mei Cai
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Jiang-Hui Meng
- Hubei Cooperative Innovation Center of Unconventional Oil and Gas, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Yan Lin
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China.
- Norwegian Institute for Water Research, 0349, Oslo, Norway.
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38
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Tang W, Su Y, Gao Y, Zhong H. Effects of Farming Activities on the Biogeochemistry of Mercury in Rice-Paddy Soil Systems. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:635-642. [PMID: 31053868 DOI: 10.1007/s00128-019-02627-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
The biogeochemistry of mercury (Hg) in rice-paddy soil systems raises concerns, given that (1) the redox potential in paddy soil favors Hg methylation and (2) rice plants have a strong ability to accumulate methylmercury (MeHg), making rice an important source for MeHg exposure to humans. Therefore, all factors affecting the behavior of Hg in rice-paddy soils might impact Hg accumulation in rice, with its subsequent potential risks. As a typical wetland, paddy soils are managed by humans and affected by anthropogenic activities, such as agronomic measures, which would impact soil properties and thus Hg biogeochemistry. In this paper, we reviewed recent advances in the effects of farming activities including water management, fertilizer application and rotation on Hg biogeochemistry, trying to elucidate the factors controlling Hg behavior and thus the ecological risks in rice-paddy soil systems. This review might provide new thoughts on Hg remediation and suggest avenues for further studies.
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Affiliation(s)
- Wenli Tang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China
| | - Yao Su
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China
| | - Yuxi Gao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Laboratory of Metallomics and Nanometallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China.
- Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, ON, Canada.
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Li Y, Zhao J, Zhong H, Wang Y, Li H, Li YF, Liem-Nguyen V, Jiang T, Zhang Z, Gao Y, Chai Z. Understanding Enhanced Microbial MeHg Production in Mining-Contaminated Paddy Soils under Sulfate Amendment: Changes in Hg Mobility or Microbial Methylators? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1844-1852. [PMID: 30636405 DOI: 10.1021/acs.est.8b03511] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Elevated methylmercury (MeHg) production in mining-contaminated paddy soils, despite the high fraction of refractory HgS(s), has been frequently reported, while the underlying mechanisms are not fully understood. Here, we hypothesized that sulfate input, via fertilization, rainfall, and irrigation, is critical in mobilizing refractory HgS(s) and thus enhancing Hg methylation in mining-contaminated paddy soils. To test this hypothesis, the effects of sulfate amendment on Hg methylation and MeHg bioaccumulation in mining-contaminated soil-rice systems were examined. The results indicated 28-61% higher net MeHg production in soils under sulfate amendment (50-1000 mg kg-1), which in turn increased grain MeHg levels by 22-55%. The enhancement of Hg methylation by Hg mobilization in sulfate-amended soils was supported by two observations: (1) the increased Hg(aq) release from HgS(s), the dominant Hg species in the paddy soils, in the presence of sulfide produced following sulfate reduction and (2) the decreases of refractory HgS(s) in soils under sulfate amendment. By contrast, changes in the abundances/activities of potential microbial Hg methylators in different Hg-contaminated soils were not significant following sulfate amendment. Our results highlight the importance to consider enhanced Hg mobility and thus methylation in soils under sulfate amendment.
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Affiliation(s)
- Yunyun Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation , Fujian Agriculture and Forestry University , Fuzhou 350002 , Fujian China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University , Nanjing 210023 , China
- Environmental and Life Sciences Program (EnLS) , Trent University , Peterborough , Ontario Canada
| | - Yongjie Wang
- School of Geographic Sciences , East China Normal University , Shanghai 200241 , China
| | - Hong Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Yu-Feng Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Van Liem-Nguyen
- School of Science and Technology , Örebro University , SE-70281 , Örebro , Sweden
| | - Tao Jiang
- Department of Environmental Science and Engineering, College of Resources and Environment , Southwest University , Chongqing 400716 , China
- Department of Forest Ecology and Management , Swedish University of Agricultural Sciences , Umeå SE-90183 , Sweden
| | - Zhiyong Zhang
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
| | - Zhifang Chai
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China
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Xu Q, Zhao L, Wang Y, Xie Q, Yin D, Feng X, Wang D. Bioaccumulation characteristics of mercury in fish in the Three Gorges Reservoir, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 243:115-126. [PMID: 30172117 DOI: 10.1016/j.envpol.2018.08.048] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/12/2018] [Accepted: 08/16/2018] [Indexed: 06/08/2023]
Abstract
Newly constructed reservoirs were recognized as hotspot of mercury (Hg) methylation, and then methylmercury (MeHg) accumulation in food chains. The risk of elevated MeHg concentrations in fish is one of the most important concerns in newly constructed reservoirs. The Three Gorges Reservoir (TGR) is one of the largest reservoirs in the world. However, the distribution and bioaccumulation characteristics of Hg species within the food chains and its potential ecological risk in the TGR remain poorly understood. In this study, 264 fish individuals covering 18 species were collected from the TGR. Total mercury (THg) and MeHg concentrations in different organs (gill, heart, liver, muscle and swim bladder) of fish species were analyzed; the values of δ13C and δ15N in fish muscle were determined as well to reveal the biomagnification properties of Hg in food chains. Our results showed that concentrations of THg (0.5-272 ng g-1, w.w.) and MeHg (0.1-199 ng g-1, w.w.) in fish muscle from the TGR ubiquitously fall below the safe fish consumption limit on Hg recommended by WHO (500 ng g-1, w.w.) and the US-EPA Water Quality Criterion for MeHg (300 ng g-1, w.w.). The short food web jointly with the limited trophic magnification factor in the TGR explained the relatively low Hg concentrations in predators. Among the five fish organs, muscle represented the highest Hg concentrations, followed by heart, liver, swim bladder, and gill, suggesting that muscle has the highest ability to accumulate Hg compared to the other organs. More importantly, no discernible "reservoir effect" was observed in the TGR within the initial few years after impoundment due to its special eco-environment including: 1) neutral and slightly alkaline pH and low dissolved organic carbon of water, 2) less vegetation coverage in inundated areas, 3) simple food web.
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Affiliation(s)
- Qinqin Xu
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Lei Zhao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Qing Xie
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Deliang Yin
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, PR China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, PR China.
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Zhao JY, Ye ZH, Zhong H. Rice root exudates affect microbial methylmercury production in paddy soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 242:1921-1929. [PMID: 30072222 DOI: 10.1016/j.envpol.2018.07.072] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/16/2018] [Accepted: 07/16/2018] [Indexed: 06/08/2023]
Abstract
Microbial methylmercury (MeHg) production in contaminated soil-rice systems and its accumulation in rice pose health risks to consumers, especially those in Asia. However, the mechanism responsible for microbial MeHg production in paddy soils is far from clear. While previous studies examined the effect of soil and microbial factors on soil MeHg levels, in this work we explored the impact of rice cultivation itself on microbial MeHg production, focusing on the root exudate organic matter as a potential source of electron donors for microbial methylators. Effects of the cultivation of two rice cultivars, Heigu246 (H-rice) and Neiwuyou8015 (N-rice), on MeHg production in soils were therefore investigated in pot and batch incubation experiments. Soil MeHg levels measured in H-rice treatment during the heading and harvest stages were 18-49% higher than in the control and 23-108% higher than in N-rice treatment. Consequently, MeHg levels in grain, straw, and root were 38%, 81%, and 40% higher in H-rice than those in N-rice, which was mainly attributed to cultivar-specific MeHg production in soils. Results of the batch experiments suggested that root exudate organic matter could be responsible for MeHg production in soils during rice cultivation, by increasing the abundances of potential microbial methylators. For instance, root exudate organic matter increased copy numbers of Hg methylation genes (hgcA) in soils 4.1-fold. Furthermore, the 211% higher concentration of acetate (a key electron donor for microbial methylators) in the root exudate of H-rice could account for the higher MeHg production under H-rice than N-rice cultivation. Our results suggest that root exudate organic matter, especially acetate, as its key component, contributes to the elevated soil MeHg concentrations during rice cultivation. The proposed mechanism provides new insights into the elevated risk of MeHg production in contaminated soil-rice systems, as well as cultivar-specific MeHg bioaccumulation.
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Affiliation(s)
- Jia-Yin Zhao
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Zhi-Hong Ye
- State Key Laboratory for Bio-control and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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Tanner KC, Windham-Myers L, Marvin-DiPasquale M, Fleck JA, Tate KW, Linquist BA. Methylmercury Dynamics in Upper Sacramento Valley Rice Fields with Low Background Soil Mercury Levels. JOURNAL OF ENVIRONMENTAL QUALITY 2018; 47:830-838. [PMID: 30025065 DOI: 10.2134/jeq2017.10.0390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Few studies have considered how methylmercury (MeHg, a toxic form of Hg produced in anaerobic soils) production in rice ( L.) fields can affect water quality, and little is known about MeHg dynamics in rice fields. Surface water MeHg and total Hg (THg) imports, exports, and storage were studied in two commercial rice fields in the Sacramento Valley, California, where soil THg was low (25 and 57 ng g). The median concentration of MeHg in drainage water exiting the fields was 0.17 ng g (range: <0.007-2.1 ng g). Compared with irrigation water, drainage water had similar MeHg concentrations, and lower THg concentrations during the growing season. Significantly elevated drainage water MeHg and THg concentrations were observed in the fallow season compared with the growing season. An analysis of surface water loads indicates that fields were net importers of both MeHg (76-110 ng m) and THg (1947-7224 ng m) during the growing season, and net exporters of MeHg (35-200 ng m) and THg (248-6496 ng m) during the fallow season. At harvest, 190 to 700 ng MeHg m and 1400 to 1700 ng THg m were removed from fields in rice grain. Rice straw, which contained 120 to 180 ng MeHg m and 7000-10,500 ng m THg was incorporated into the soil. These results indicate that efforts to reduce MeHg and THg exports in rice drainage water should focus on the fallow season. Substantial amounts of MeHg and THg were stored in plants, and these pools should be considered in future studies.
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Liu J, Jiang T, Wang F, Zhang J, Wang D, Huang R, Yin D, Liu Z, Wang J. Inorganic sulfur and mercury speciation in the water level fluctuation zone of the Three Gorges Reservoir, China: The role of inorganic reduced sulfur on mercury methylation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 237:1112-1123. [PMID: 29153472 DOI: 10.1016/j.envpol.2017.11.045] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/06/2017] [Accepted: 11/11/2017] [Indexed: 06/07/2023]
Abstract
The water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) in China is a unique geomorphological unit that undergoes annual flooding and drying alternation cycle. The alternating redox conditions within the WLFZ are expected to result in dynamic cycling of reduced sulfur species, which could affect mercury (Hg) methylation due to the high affinity of reduced sulfur species to both inorganic divalent mercury (Hg(II)i) and methylmercury (MeHg). Variations of inorganic sulfur species (measured as acid volatile sulfide, chromium reductive sulfur, elemental sulfur, and water-soluble sulfate), total mercury (THg) and MeHg were studied at two typical WLFZ sites in the TGR from July 2015 to June 2016. Whereas the water-soluble sulfate contents stayed essentially constant, the reduced inorganic sulfur contents varied greatly as the water level changed. Compared with the control soils, the MeHg contents in the WLFZ soils increased, suggesting that water level fluctuations accelerated the methylation process of Hg(II)i. In situ Hg(II)i-methylation also appeared to occur in the sub-layer of the drained sediment during the draw-down season. The significant correlation between MeHg and elemental sulfur (S(0)) further suggests that polysulfides may have played a role in Hg(II)i-methylation by increasing the bioavailable Hg(II)i content in the WLFZ of the TGR.
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Affiliation(s)
- Jiang Liu
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg MB R3T 2N2, Canada
| | - Tao Jiang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden
| | - Feiyue Wang
- Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg MB R3T 2N2, Canada.
| | - Jinzhong Zhang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China.
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Rong Huang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Deliang Yin
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Zeyan Liu
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Jinzhu Wang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
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Zhang Y, Liu YR, Lei P, Wang YJ, Zhong H. Biochar and nitrate reduce risk of methylmercury in soils under straw amendment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 619-620:384-390. [PMID: 29156259 DOI: 10.1016/j.scitotenv.2017.11.106] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 06/07/2023]
Abstract
There is growing evidence that incorporating crop straw into soils, which is being widely encouraged in many parts of the world, could increase net methylmercury (MeHg) production in soils and MeHg accumulation in crops. We explored the possibility of mitigating the risk of increased MeHg levels under straw amendment by transforming straw into biochar (BC). Greenhouse and batch experiments were conducted, in which soil MeHg concentrations, MeHg phytoavailability and accumulation in rice, dynamics of sulfate, nitrate and abundances of sulfate reducing bacteria (SRB) were compared in 'Control' (Hg contaminated soil), 'Straw' (soil with 1% rice straw), 'Straw+BC' (soil with 1% straw and 1% biochar), and 'Straw+BC+N' (soil with 1% straw, 1% biochar and 0.12% nitrate). Our results indicate that straw amendment increased MeHg concentrations in soils (28-136% higher) and rice plants (26% higher in grains, 'Straw' versus 'Control'), while co-application of biochar with straw reduced grain MeHg levels (60% lower, 'Straw+BC' versus 'Straw'). This could be mainly attributed to the reduced MeHg availability to rice plants (phytoavailability, extraction rates of MeHg by ammonium thiosulfate) under biochar amendment (64-99% lower, 'Straw+BC' versus 'Straw'). However, biochar amendment enhanced soil MeHg levels (5-75% higher, 'Straw+BC' versus 'Control'). Interestingly, nitrate addition helped reduce soil MeHg concentrations (11-41% lower, 'Straw+BC+N' versus 'Straw+BC') by facilitating nitrate reduction while inhibiting SRB activities. Subsequently, addition of nitrate with biochar, compared with biochar alone, further reduced grain MeHg levels by 34%. Therefore, straw biochar together with nitrate could possibly be effective in mitigating the risk of MeHg under straw amendment. Furthermore, the results evidence the impacts of straw management on the risk posed by MeHg in soils and emphasize the necessity to carefully consider the straw management policy in Hg-contaminated areas.
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Affiliation(s)
- Yue Zhang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resources Reuse, Nanjing, Jiangsu Province, China
| | - Yu-Rong Liu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Pei Lei
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yong-Jie Wang
- School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resources Reuse, Nanjing, Jiangsu Province, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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45
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Olsen TA, Muller KA, Painter SL, Brooks SC. Kinetics of Methylmercury Production Revisited. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2063-2070. [PMID: 29376334 DOI: 10.1021/acs.est.7b05152] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Laboratory measurements of the biologically mediated methylation of mercury (Hg) to the neurotoxin monomethylmercury (MMHg) often exhibit kinetics that are inconsistent with first-order kinetic models. Using time-resolved measurements of filter passing Hg and MMHg during methylation/demethylation assays, a multisite kinetic sorption model, and reanalyses of previous assays, we show that competing kinetic sorption reactions can lead to time-varying availability and apparent non-first-order kinetics in Hg methylation and MMHg demethylation. The new model employing a multisite kinetic sorption model for Hg and MMHg can describe the range of behaviors for time-resolved methylation/demethylation data reported in the literature including those that exhibit non-first-order kinetics. Additionally, we show that neglecting competing sorption processes can confound analyses of methylation/demethylation assays, resulting in rate constant estimates that are systematically biased low. Simulations of MMHg production and transport in a hypothetical periphyton biofilm bed illustrate the implications of our new model and demonstrate that methylmercury production may be significantly different than projected by single-rate first-order models.
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Affiliation(s)
- Todd A Olsen
- Environmental Sciences Division, Oak Ridge National Laboratory , P.O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, United States
| | - Katherine A Muller
- Environmental Sciences Division, Oak Ridge National Laboratory , P.O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, United States
| | - Scott L Painter
- Environmental Sciences Division, Oak Ridge National Laboratory , P.O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, United States
| | - Scott C Brooks
- Environmental Sciences Division, Oak Ridge National Laboratory , P.O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, United States
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Carbon Amendments Alter Microbial Community Structure and Net Mercury Methylation Potential in Sediments. Appl Environ Microbiol 2018; 84:AEM.01049-17. [PMID: 29150503 PMCID: PMC5772229 DOI: 10.1128/aem.01049-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/28/2017] [Indexed: 01/08/2023] Open
Abstract
Neurotoxic methylmercury (MeHg) is produced by anaerobic Bacteria and Archaea possessing the genes hgcAB, but it is unknown how organic substrate and electron acceptor availability impacts the distribution and abundance of these organisms. We evaluated the impact of organic substrate amendments on mercury (Hg) methylation rates, microbial community structure, and the distribution of hgcAB+ microbes with sediments. Sediment slurries were amended with short-chain fatty acids, alcohols, or a polysaccharide. Minimal increases in MeHg were observed following lactate, ethanol, and methanol amendments, while a significant decrease (∼70%) was observed with cellobiose incubations. Postincubation, microbial diversity was assessed via 16S rRNA amplicon sequencing. The presence of hgcAB+ organisms was assessed with a broad-range degenerate PCR primer set for both genes, while the presence of microbes in each of the three dominant clades of methylators (Deltaproteobacteria, Firmicutes, and methanogenic Archaea) was measured with clade-specific degenerate hgcA quantitative PCR (qPCR) primer sets. The predominant microorganisms in unamended sediments consisted of Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria Clade-specific qPCR identified hgcA+Deltaproteobacteria and Archaea in all sites but failed to detect hgcA+Firmicutes Cellobiose shifted the communities in all samples to ∼90% non-hgcAB-containing Firmicutes (mainly Bacillus spp. and Clostridium spp.). These results suggest that either expression of hgcAB is downregulated or, more likely given the lack of 16S rRNA gene presence after cellobiose incubation, Hg-methylating organisms are largely outcompeted by cellobiose degraders or degradation products of cellobiose. These results represent a step toward understanding and exploring simple methodologies for controlling MeHg production in the environment.IMPORTANCE Methylmercury (MeHg) is a neurotoxin produced by microorganisms that bioacummulates in the food web and poses a serious health risk to humans. Currently, the impact that organic substrate or electron acceptor availability has on the mercury (Hg)-methylating microorganisms is unclear. To study this, we set up microcosm experiments exposed to different organic substrates and electron acceptors and assayed for Hg methylation rates, for microbial community structure, and for distribution of Hg methylators. The sediment and groundwater was collected from East Fork Poplar Creek in Oak Ridge, TN. Amendment with cellobiose (a lignocellulosic degradation by-product) led to a drastic decrease in the Hg methylation rate compared to that in an unamended control, with an associated shift in the microbial community to mostly nonmethylating Firmicutes This, along with previous Hg-methylating microorganism identification methods, will be important for identifying strategies to control MeHg production and inform future remediation strategies.
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Li P, Du B, Maurice L, Laffont L, Lagane C, Point D, Sonke JE, Yin R, Lin CJ, Feng X. Mercury Isotope Signatures of Methylmercury in Rice Samples from the Wanshan Mercury Mining Area, China: Environmental Implications. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12321-12328. [PMID: 28958148 DOI: 10.1021/acs.est.7b03510] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Rice consumption is the primary pathway of methylmercury (MeHg) exposure for residents in mercury-mining areas of Guizhou Province, China. In this study, compound-specific stable isotope analysis (CSIA) of MeHg was performed on rice samples collected in the Wanshan mercury mining area. An enrichment of 2.25‰ in total Hg (THg) δ202Hg was observed between rice and human hair, and THg Δ199Hg in hair was 0.12‰ higher than the value in rice. Rice and human hair samples in this study show distinct Hg isotope signatures compared to those of fish and human hair of fish consumers collected in China and other areas. Distinct Hg isotope signatures were observed between IHg and MeHg in rice samples (in mean ± standard deviation: δ202HgIHg at -2.30‰ ± 0.49‰, Δ199HgIHg at -0.08‰ ± 0.04‰, n = 7; δ202HgMeHg at -0.80‰ ± 0.25‰, Δ199HgMeHg at 0.08‰ ± 0.04‰, n = 7). Using a binary mixing model, it is estimated that the atmospheric Hg contributed 31% ± 16% of IHg and 17% ± 11% of THg in the rice samples and the IHg in soil caused by past mining activities contributed to the remaining Hg. This study demonstrated that Hg stable isotopes are good tracers of human MeHg exposure to fish and rice consumption, and the isotope data can be used for identifying the sources of IHg and MeHg in rice.
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Affiliation(s)
| | - Buyun Du
- University of Chinese Academy of Sciences , Beijing 100049, China
| | - Laurence Maurice
- Observatory Midi-Pyrénées, Geosciences Environment Toulouse Laboratory, Research Institute for the Development (IRD), University of Toulouse and CNRS , 31400 Toulouse, France
| | - Laure Laffont
- Observatory Midi-Pyrénées, Geosciences Environment Toulouse Laboratory, Research Institute for the Development (IRD), University of Toulouse and CNRS , 31400 Toulouse, France
| | - Christelle Lagane
- Observatory Midi-Pyrénées, Geosciences Environment Toulouse Laboratory, Research Institute for the Development (IRD), University of Toulouse and CNRS , 31400 Toulouse, France
| | - David Point
- Observatory Midi-Pyrénées, Geosciences Environment Toulouse Laboratory, Research Institute for the Development (IRD), University of Toulouse and CNRS , 31400 Toulouse, France
| | - Jeroen E Sonke
- Observatory Midi-Pyrénées, Geosciences Environment Toulouse Laboratory, Research Institute for the Development (IRD), University of Toulouse and CNRS , 31400 Toulouse, France
| | | | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University , Beaumont, Texas 77710, United States
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48
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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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Xu X, Meng B, Zhang C, Feng X, Gu C, Guo J, Bishop K, Xu Z, Zhang S, Qiu G. The local impact of a coal-fired power plant on inorganic mercury and methyl-mercury distribution in rice (Oryza sativa L.). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 223:11-18. [PMID: 28139322 DOI: 10.1016/j.envpol.2016.11.042] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/15/2016] [Accepted: 11/14/2016] [Indexed: 06/06/2023]
Abstract
Emission from coal-fired power plants is one of the major anthropogenic sources of mercury (Hg) in the environment, because emitted Hg can be quickly deposited nearby the source, attention is paid to the effects of coal-burning facilities on levels of toxic methyl-mercury (MeHg) in biota near such sources. Since rice is an agricultural crop that can bio-accumulate MeHg, the potential effects of a large Hg-emitting coal-fired power plant in Hunan Province, China on both inorganic Hg (Hg(II)) and MeHg distributions in rice was investigated. Relatively high MeHg (up to 3.8 μg kg-1) and Hg(II) (up to 22 μg kg-1) concentrations were observed in rice samples collected adjacent to the plant, suggesting a potential impact of Hg emission from the coal fired power plant on the accumulation of Hg in rice in the area. Concentrations of MeHg in rice were positively correlated with soil MeHg, soil S, and gaseous elemental Hg (GEM) in ambient air. Soil MeHg was the most important factor controlling MeHg concentrations in rice. The methylation of Hg in soils may be controlled by factors such as the chemical speciation of inorganic Hg, soil S, and ambient GEM.
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Affiliation(s)
- Xiaohang Xu
- 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
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Chao 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
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Chunhao Gu
- Department of Ecosystems Science and Management, University of Wyming, 82071, United States
| | - Jianyang Guo
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Kevin Bishop
- Department of Earth Sciences, University of Uppsala, Uppsala, Sweden; Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Zhidong Xu
- 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
| | - Sensen Zhang
- School of Geosciences and Info-Physics, Central South University, CAS, Changsha, 410000, China
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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Boyd ES, Yu RQ, Barkay T, Hamilton TL, Baxter BK, Naftz DL, Marvin-DiPasquale M. Effect of salinity on mercury methylating benthic microbes and their activities in Great Salt Lake, Utah. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 581-582:495-506. [PMID: 28057343 DOI: 10.1016/j.scitotenv.2016.12.157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 06/06/2023]
Abstract
Surface water and biota from Great Salt Lake (GSL) contain some of the highest documented concentrations of total mercury (THg) and methylmercury (MeHg) in the United States. In order to identify potential biological sources of MeHg and controls on its production in this ecosystem, THg and MeHg concentrations, rates of Hg(II)-methylation and MeHg degradation, and abundances and compositions of archaeal and bacterial 16 rRNA gene transcripts were determined in sediment along a salinity gradient in GSL. Rates of Hg(II)-methylation were inversely correlated with salinity and were at or below the limits of detection in sediment sampled from areas with hypersaline surface water. The highest rates of Hg(II)-methylation were measured in sediment with low porewater salinity, suggesting that benthic microbial communities inhabiting less saline environments are supplying the majority of MeHg in the GSL ecosystem. The abundance of 16S rRNA gene transcripts affiliated with the sulfate reducer Desulfobacterium sp. was positively correlated with MeHg concentrations and Hg(II)-methylation rates in sediment, indicating a potential role for this taxon in Hg(II)-methylation in low salinity areas of GSL. Reactive inorganic Hg(II) (a proxy used for Hg(II) available for methylation) and MeHg concentrations were inversely correlated with salinity. Thus, constraints imposed by salinity on Hg(II)-methylating populations and the availability of Hg(II) for methylation are inferred to result in higher MeHg production potentials in lower salinity environments. Benthic microbial MeHg degradation was also most active in lower salinity environments. Collectively, these results suggest an important role for sediment anoxia and microbial sulfate reducers in the production of MeHg in low salinity GSL sub-habitats and may indicate a role for salinity in constraining Hg(II)-methylation and MeHg degradation activities by influencing the availability of Hg(II) for methylation.
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Affiliation(s)
- Eric S Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, United States.
| | - Ri-Qing Yu
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, United States
| | - Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, United States
| | - Trinity L Hamilton
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, United States
| | - Bonnie K Baxter
- Department of Biology, Westminster College, Salt Lake City, UT 84105, United States
| | - David L Naftz
- United States Geological Survey, Helena, MT 59601, United States
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