title: Mercury methylation in rice paddies and its possible controlling factors in the Hg mining area, Guizhou province, Southwest China.
abstract: Understanding mercury (Hg) methylation/demethylation processes and the factors controlling methylmercury (MeHg) production within the rice paddy ecosystem of Hg mining areas is critical to assess the risk of MeHg contamination in rice grain. Two typical Hg-contaminated mining sites, a current-day artisanal site (Gouxi) and an abandoned site (Wukeng), were chosen in this study. We qualified the in situ specific methylation/demethylation rate constants in rice paddy soil during a complete rice-growing season. Our results demonstrate that MeHg levels in rice paddy soil were a function of both methylation and demethylation processes and the net methylation potential in the rice paddy soil reflected the measured MeHg production at any time point. Sulfate stimulating the activity of sulfate-reducing bacteria was a potentially important metabolic pathway for Hg methylation in rice paddies. We suggest that bioavailable Hg derived from new atmospheric deposition appears to be the primary factor regulating net MeHg production in rice paddies.
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China; College of Resources Environment, Southwest University, Chongqing 400716, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China.
authors.forename: Guangle
authors.initials: G
authors.lastname: Qiu
authors.affiliation: Soil and Earth Sciences, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand.
authors.forename: Christopher W N
authors.initials: CWN
authors.lastname: Anderson
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China. Electronic address: mengbo@vip.skleg.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Meng
authors.affiliation: College of Resources Environment, Southwest University, Chongqing 400716, PR China.
authors.forename: Dingyong
authors.initials: D
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China.
authors.forename: Lihai
authors.initials: L
authors.lastname: Shang
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China.
authors.forename: Haiyu
authors.initials: H
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China.
authors.forename: Xinbin
authors.initials: X
authors.lastname: Feng
mesh_terms: D002681:China; D004784:Environmental Monitoring; D008628:Mercury / Q000737:chemistry*; D008745:Methylation; D008767:Methylmercury Compounds / Q000378:metabolism; D008906:Mining; D012275:Oryza / Q000254:growth & development*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D008767:Methylmercury Compounds; D012987:Soil; D012989:Soil Pollutants; D008628:Mercury
keywords: Demethylation; Mercury mining area; Methylation; Rice paddy