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Chen J, Hu G, Liu J, Poulain AJ, Pu Q, Huang R, Meng B, Feng X. The divergent effects of nitrate and ammonium application on mercury methylation, demethylation, and reduction in flooded paddy slurries. JOURNAL OF HAZARDOUS MATERIALS 2023; 460:132457. [PMID: 37669605 DOI: 10.1016/j.jhazmat.2023.132457] [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: 04/28/2023] [Revised: 07/30/2023] [Accepted: 08/30/2023] [Indexed: 09/07/2023]
Abstract
The production of methylmercury (MeHg) in flooded paddy fields determines its accumulation in rice grains; this, in turn, results in MeHg exposure risks for not only rice-eating humans but also wildlife. Nitrogen (N) fertilizers have been widely applied in rice cultivation fields to supply essential nutrients. However, the effects of N fertilizer addition on mercury (Hg) transformations are not unclear. This limits our understanding of MeHg formation in rice paddy ecosystems. In this study, we spiked three Hg tracers (200HgII, Me198Hg, and 202Hg0) in paddy slurries fertilized with urea, ammonium, and nitrate. The influences of N fertilization on Hg methylation, demethylation, and reduction and the underlying mechanisms were elucidated. The results revealed that dissimilatory nitrate reduction was the dominant process in the incubated paddy slurries. Nitrate addition inhibited HgII reduction, HgII methylation, and MeHg demethylation. Competition between nitrates and other electron acceptors (e.g., HgII, sulfate, or carbon dioxide) under dark conditions was the mechanism underlying nitrate-regulated Hg transformation. Ammonium and urea additions promoted HgII reduction, and anaerobic ammonium oxidation coupled with HgII reduction (Hgammox) was likely the reason. This work highlighted that nitrate addition not only inhibited HgII methylation but also reduced the demethylation of MeHg and therefore may generate more accumulation of MeHg in the incubated paddy slurries. Findings from this study link the biogeochemical cycling of N and Hg and provide crucial knowledge for assessing Hg risks in intermittently flooded wetland ecosystems.
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Affiliation(s)
- Ji Chen
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Gongren Hu
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, China
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Alexandre J Poulain
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Rong Huang
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Pei P, Sun T, Xu Y, Sun Y. Soil aggregate-associated mercury (Hg) and organic carbon distribution and microbial community characteristics under typical farmland-use types. CHEMOSPHERE 2021; 275:129987. [PMID: 33631401 DOI: 10.1016/j.chemosphere.2021.129987] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 01/28/2021] [Accepted: 02/11/2021] [Indexed: 06/12/2023]
Abstract
In order to get insight into the distribution characteristics of mercury (Hg) and organic carbon in soil aggregates, and the diversity and composition of soil microbial community under different farmland-use types (soil form three adjacent cultivation systems, i.e., corn, vegetable, and rice fields, named as CFS, VFS, and RFS), a field investigation close to Wanshan Hg mining area was conducted. Results indicated that soil total Hg (0-20 cm) presented in decreasing order of RFS (5.27 mg kg-1) > VFS (4.32 mg kg-1) > CFS (2.21 mg kg-1), implying soils from rice field with higher ability of Hg accumulation. Soil aggregate-associated Hg and organic carbon enriched with the decrease of particle size under all farmland-use types, with the maximum at microaggregates (<0.053 mm). Due to the mass ratio of soil aggregates fraction, soil aggregate-associated Hg and organic carbon mainly distributed in >2 mm particles for RFS, whereas 0.25-2 mm particles for CFS and VFS. Furthermore, 16S rRNA results revealed the obvious differences in RFS and dry land soils (CFS and VFS), such as the observed species and unique OUTs, Shannon index, relative abundance at phylum and genus, which implied the diversity and composition of soil microbial community were greatly affected by farmland-use types. Spearman correlation and RDA results suggested farmland-use types, pH and total Hg were main drives for differences in soil microbial community. These findings provide evidence that farmland-use type is an important factor that affects soil total Hg accumulation, soil aggregate-associated Hg and organic carbon distribution, as well as the indigenous microbial community profiles.
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Affiliation(s)
- Penggang Pei
- Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture and Rural Affairs (MARA), Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China; Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China
| | - Tao Sun
- Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture and Rural Affairs (MARA), Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China; Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China
| | - Yingming Xu
- Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture and Rural Affairs (MARA), Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China; Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China
| | - Yuebing Sun
- Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture and Rural Affairs (MARA), Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China; Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Agro-Environmental Protection Institute, MARA, Tianjin, 300191, China.
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Zhu H, Teng Y, Wang X, Zhao L, Ren W, Luo Y, Christie P. Changes in clover rhizosphere microbial community and diazotrophs in mercury-contaminated soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 767:145473. [PMID: 33636759 DOI: 10.1016/j.scitotenv.2021.145473] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/23/2021] [Accepted: 01/24/2021] [Indexed: 06/12/2023]
Abstract
Little is known about the response of the soil microbiome (including bacteria in the rhizosphere of legumes such as clover) to mercury (Hg) despite the toxicity of Hg to soil microorganisms. Here, Hg-contaminated soils collected from Guizhou province, southwest China, were divided into three groups according to their Hg contents and were planted with clover. High-throughput sequencing of bacterial 16S rRNA and nitrogenase (nifH) genes and quantitative polymerase chain reaction (qPCR) were used to study the response of bacteria and diazotrophs to soil Hg stress and the effects of Hg on the abundance of functional genes in rhizosphere soils. High concentrations of soil Hg decreased bacterial community abundance and diversity and increased the abundance and diversity of nitrogen-fixing bacteria. LEfSe analysis indicates that Rhizobium was a biomarker at sites with high soil Hg contents and the co-occurrence network results indicate a positive relationship between the abundance of the dominant module (from the co-occurrence network analysis) of Rhizobiaceae and soil Hg concentration. Structural equation modeling (SEM) indicates that the Hg content in the clover shoots (ShootHg) was negatively correlated with the abundance of the mercury reductase (merA) gene (r = -0.26, P < 0.05) and the organomercury lyase (merB) gene (r = -0.23, P < 0.05) in rhizosphere soils. Moreover, correlation analysis and SEM indicate that soil total nitrogen (TN), nitrate‑nitrogen (NO3-N), soil organic matter (SOM), and available molybdenum (Mo) contents were also important factors affecting the structure of the microbial community and the abundance of functional genes. The results provide a basis for further study of the mechanism(s) by which microorganisms may impart tolerance of clover to Hg in contaminated soils.
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Affiliation(s)
- Haixia Zhu
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Ying Teng
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
| | - Xiaomi Wang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Ling Zhao
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Wenjie Ren
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Yongming Luo
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Peter Christie
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
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Tian HJ, Feng J, Zhang LM, He JZ, Liu YR. Ecological drivers of methanotrophic communities in paddy soils around mercury mining areas. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 721:137760. [PMID: 32169650 DOI: 10.1016/j.scitotenv.2020.137760] [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: 01/08/2020] [Revised: 03/04/2020] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
Methanotrophs play a crucial role in mitigating methane (CH4) emission by oxidizing produced CH4 in paddy soils; however, ecological drivers of methanotrophic community in the soils around heavy metal contaminated areas remain unclear. In this study, we evaluated the effects of heavy metal pollution and soil properties on the abundance, diversity and composition of methanotrophic community in paddy soils from two typical mercury (Hg) mining regions in southwest China. The results of random forest and structure equation models suggest that both heavy metal content and soil nutrients greatly influenced the attributes of methanotrophic community. In general, the abundance and diversity of methanotrophs were negatively related to soil Hg content, but showed positive correlation with soil organic carbon content. However, the other metals (cadmium (Cd), nickel (Ni), lead (Pb), arsenic (As), zinc (Zn)) had inconsistent associations with the microbial indexes of methanotrophic community in the soil. Elevated levels of heavy metal and nutrients in the soils shifted the community composition of methanotrophs. For example, Pb, As and Zn contents had negative associations with the relative abundance of Methylocaldum. In addition, changes in the relative abundance of ecological clusters within the co-occurrence network of methanotrophs were related to metal contents and soil properties. Together, our findings provide novel insights into understanding ecological drivers of methanotrophic community in paddy soils around Hg mining regions, with important implications for mitigating CH4 emissions in terrestrial ecosystems.
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Affiliation(s)
- Hua-Jing Tian
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiao Feng
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
| | - Li-Mei Zhang
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ji-Zheng He
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yu-Rong Liu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
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Gygax S, Gfeller L, Wilcke W, Mestrot A. Emerging investigator series: mercury mobility and methylmercury formation in a contaminated agricultural flood plain: influence of flooding and manure addition. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:2008-2019. [PMID: 31617529 DOI: 10.1039/c9em00257j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The fate and the methylation of mercury (Hg) in the terrestrial environment are still poorly understood and although the main drivers of release and methylation of mercury in soils are known (low redox potential and microbial carbon availability) their interactions are not well understood. This is of concern since many agriculturally used floodplains, where the recurring flooding and agricultural practices (e.g. manure amendments) may have an impact on the fate and the biomethylation of Hg, are at the same time Hg-contaminated. In this study, we modified and validated existing methods to extract and analyze methylmercury (MeHg) by HPLC-ICP-MS in soils and we assessed the Hg and MeHg concentrations in three fields situated in a Hg polluted agricultural floodplain. Further, we incubated the top soil from the three studied fields for 11 days under flooded conditions in presence or absence of 2 mass% of cow manure, a common agricultural amendment in the area. Total Hg and MeHg concentrations ranged from <limit of detection (LOD, 0.012 mg kg-1) to 28.2 mg kg-1 and from 1.2 to 7.8 μg kg-1 respectively. Hg was released to the soil solution after 12 hours with a maximum between day 2 and day 7. MeHg levels in the soil solution were <LOD although it was found in the soil before and after the incubation. The addition of cow manure to saturated soils led to an increase in the MeHg concentrations of the soil solid phase by up to fivefold to a maximum of 26.4 ± 1.1 μg kg-1 (n = 3). Our study demonstrates that the combination of low redox potential because of flooding with common agricultural practices such as the amendment of manures enhances the formation of toxic MeHg.
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Affiliation(s)
- Sebastian Gygax
- Institute of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland
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Zhang Y, Fu CY, Liu XL, Li XH, Jing QC, Wei XF, Shi TH, Dong YL, Yan PP. Effect of poultry wastewater irrigation on nitrogen, phosphorus and carbon contents in farmland soil. OPEN CHEM 2018. [DOI: 10.1515/chem-2018-0111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AbstractThe goal of this study was to assess the suitability of poultry wastewater for the irrigation of farmland soil as a possible substitute for regular water and fertilizers. The vertical and spatial variability of soil total nitrogen (STN), soil total phosphorus (STP) and soil organic carbon (SOC) was analyzed during the growing season of summer maize in two types of soil: an experimental group (EG) soil, irrigated once only with poultry wastewater, and a control group (CG) soil, irrigated once only with regular water. Results revealed no difference in STP concentration, SOC concentration, nitrogen storage and phosphorus storage between EG and CG soils (all p>0.05); STN concentration in the 5–15 cm layer and carbon storage were higher in EG soil (p<0.05) while remaining within safety limits. Overall, single-time irrigation by poultry wastewater enhances nitrogen and carbon content of soil and does not pose a serious risk of pollution for ground water.
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Affiliation(s)
- Yan Zhang
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Chun-Yan Fu
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Xue-Lan Liu
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Xin-Hua Li
- Shandong Institute of Agricultural Sustainable Development, Jinan 250100, P. RJinanChina
| | - Qing-Chuan Jing
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Xiang-Fa Wei
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Tian-Hong Shi
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Yi-Lei Dong
- Poultry Institute, Shangdong Academy of Agricultural Science, Jinan 250023, P. RJinanChina
| | - Pei-Pei Yan
- Shandong Institute of Agricultural Sustainable Development, Jinan 250100, P. RJinanChina
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Liu YR, Dong JX, Han LL, Zheng YM, He JZ. Influence of rice straw amendment on mercury methylation and nitrification in paddy soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 209:53-59. [PMID: 26629646 DOI: 10.1016/j.envpol.2015.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 11/09/2015] [Accepted: 11/16/2015] [Indexed: 06/05/2023]
Abstract
UNLABELLED Currently, rice straw return in place of burning is becoming more intensive in China than observed previously. However, little is known on the effect of returned rice straw on mercury (Hg) methylation and microbial activity in contaminated paddy fields. Here, we conduct a microcosm experiment to evaluate the effect of rice straw amendment on the Hg methylation and potential nitrification in two paddy soils with distinct Hg levels. Our results show that amended rice straw enhanced Hg methylation for relatively high Hg content soil, but not for low Hg soil, spiking the same additional fresh Hg. methylmercury (MeHg) concentration was significantly correlated to the dissolved organic carbon (DOC) content and relative abundance of dominant microbes associated with Hg methylation. Similarly, amended rice straw was found to only enhance the potential nitrification rate in soil with relatively high Hg content. These findings provide evidence that amended rice straw differentially modulates Hg methylation and nitrification in Hg contaminated soils possibly resulting from different characteristics in the soil microbial community. This highlights that caution should be taken when returning rice straw to contaminated paddy fields, as this practice may increase the risk of more MeHg production. MAIN FINDING Rice straw amendment enhanced both Hg methylation and nitrification potential in the relatively high, but not low, Hg soil.
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Affiliation(s)
- Yu-Rong Liu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Ji-Xin Dong
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Li-Li Han
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yuan-Ming Zheng
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ji-Zheng He
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Faculty of Veterinary and Agricultural Sciences, the University of Melbourne, Parkville 3010, Victoria, Australia
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Analysis of the microbial community structure by monitoring an Hg methylation gene (hgcA) in paddy soils along an Hg gradient. Appl Environ Microbiol 2014; 80:2874-9. [PMID: 24584244 DOI: 10.1128/aem.04225-13] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Knowledge of the diversity of mercury (Hg)-methylating microbes in the environment is limited due to a lack of available molecular biomarkers. Here, we developed novel degenerate PCR primers for a key Hg-methylating gene (hgcA) and amplified successfully the targeted genes from 48 paddy soil samples along an Hg concentration gradient in the Wanshan Hg mining area of China. A significant positive correlation was observed between hgcA gene abundance and methylmercury (MeHg) concentrations, suggesting that microbes containing the genes contribute to Hg methylation in the sampled soils. Canonical correspondence analysis (CCA) showed that the hgcA gene diversity in microbial community structures from paddy soils was high and was influenced by the contents of total Hg, SO4(2-), NH4(+), and organic matter. Phylogenetic analysis showed that hgcA microbes in the sampled soils likely were related to Deltaproteobacteria, Firmicutes, Chloroflexi, Euryarchaeota, and two unclassified groups. This is a novel report of hgcA diversity in paddy habitats, and results here suggest a link between Hg-methylating microbes and MeHg contamination in situ, which would be useful for monitoring and mediating MeHg synthesis in soils.
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Liu YR, Zheng YM, Zhang LM, He JZ. Linkage between community diversity of sulfate-reducing microorganisms and methylmercury concentration in paddy soil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2014; 21:1339-1348. [PMID: 23900947 DOI: 10.1007/s11356-013-1973-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 07/01/2013] [Indexed: 06/02/2023]
Abstract
Sulfate-reducing microorganisms (SRM) have been thought to play a key role in mercury (Hg) methylation in anoxic environments. The current study examined the linkage between SRM abundance and diversity and contents of methylmercury (MeHg) in paddy soils collected from a historical Hg mining area in China. Soil profile samples were collected from four sites over a distance gradient downstream the Hg mining operation. Results showed that MeHg content in the soil of each site significantly decreased with the extending distance away from Hg mine. Soil MeHg content was correlated positively with abundance of SRM and the contents of organic matter (OM), NH4(+), SO4(2-), and Hg. The abundances of SRM based on dissimilatory (bi) sulfite reductase (dsrAB) gene at 0-40 cm depths were higher than those at 40-80 cm depth at all sites. The SRM community composition varied in the soils of different sampling sites following terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analyses, which appeared to be correlated with contents of MeHg, OM, NH4(+), and SO4(2-) through canonical correspondence analysis. The dominant groups of SRM in the soils examined belonged to Deltaproteobacteria and some unknown SRM clusters that could have potential for Hg methylation. These results advance our understanding of the relationship between SRM and methylmercury concentration in paddy soil.
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Affiliation(s)
- Yu-Rong Liu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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