title: Effects of sulfate and selenite on mercury methylation in a mercury-contaminated rice paddy soil under anoxic conditions.
abstract: Biogeochemical cycling of sulfur and selenium (Se) could play an important role in methylmercury (MeHg) dynamics in soil, while their potential effects on MeHg production in rice paddy soil are less understood. The main objective of this study was to explore the effects of sulfate and selenite on net MeHg production in contaminated rice paddy soil, characterized with massive MeHg production and thus MeHg accumulation in rice. A series of microcosm incubation experiments were conducted using a contaminated paddy soil amended with sulfate and/or selenite, in which sulfate-reducing bacteria were mainly responsible for MeHg production. Our results demonstrated that sulfate addition reduced solid and dissolved MeHg levels in soils by ≤18 and ≤25 %, respectively. Compared to sulfate, selenite was more effective in inhibiting net MeHg production, and the inhibitory effect depended largely on amended selenite doses. Moreover, sulfate input played a dual role in affecting Hg-Se interactions in soil, which could be explained by the dynamics of sulfate under anoxic conditions. Therefore, the effects of sulfate and selenium input should be carefully considered when assessing risk of Hg in anoxic environments (e.g., rice paddy field and wetland).
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Dang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China. zhonghuan@nju.edu.cn.|Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada. zhonghuan@nju.edu.cn.
authors.forename: Huan
authors.initials: H
authors.lastname: Zhong
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China.
authors.forename: Zhongbo
authors.initials: Z
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
mesh_terms: D008628:Mercury / Q000378:metabolism*; D008745:Methylation; D008767:Methylmercury Compounds / Q000737:chemistry / Q000378:metabolism*; D012275:Oryza / Q000737:chemistry / Q000378:metabolism*; D020887:Selenious Acid / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*
chemical_list: D008767:Methylmercury Compounds; D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D020887:Selenious Acid; D008628:Mercury
keywords: Methylmercury; Paddy soil; Selenium; Sulfate