Biochar has been used increasingly as a soil additive to control mercury(Hg)pollution in paddy rice fields.As the most active component of soil organic matter,soil dissolved organic matter(DOM)plays a vital role in the environmental fate of contaminants.However,there are very few studies to determine the impact of biochar on the Hg cycle in rice paddies using insights from DOM.This study used original and modified biochar to investigate their effect on DOM dynamics and their potential impact on methylmercury(MeHg)production and bioaccumulation in rice plants.Porewater DOM was collected to analyze the variations in soil-derived DOM in paddy soils.The results showed that the addition of biochar,whether in original or modified form,significantly reduced the bioaccumulation of MeHg in rice plants,especially in hulls and grains(p＜0.05).However,MeHg production in soils was only inhib-ited by the modified biochar.Biochar addition induced a significant increase in DOM's aro-maticity and molecular weight(p＜0.05),which decreased Hg bioavailability.Furthermore,enhanced microbial activity was also observed in DOM(p＜0.05),further increasing MeHg production in the soil.Thus,the effect of biochar on the fate of Hg cycle involves competi-tion between the two different roles of DOM.This study identified a specific mechanism by which biochar affects Hg behavior in rice paddy soil and contributes to understanding the more general influence of biochar in agriculture and contaminant remediation.

Siqi Zhang;Mingxing Wang;Jiang Liu;Shanyi Tian;Xueling Yang;Guangquan Xiao;Guomin Xu;Tao Jiang;Dingyong Wang

Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin,Department of Environmental Sciences and Engineering,College of Resources and Environment,Southwest University,Chongqing 400716,China;State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,China;Soil Ecology Laboratory,College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China;National Engineering Research Center for Compounding and Modification of Polymer Materials,Guiyang 550014,China;Guizhou Material Industrial Technology Institute,Guiyang 550014,China;Institute of Environment and Health,Jianghan University,Wuhan 430056,China

环境科学学报（英文版）

[1]Siqi Zhang;Mingxing Wang;Jiang Liu;Shanyi Tian;Xueling Yang;Guangquan Xiao;Guomin Xu;Tao Jiang;Dingyong Wang-.Biochar affects methylmercury production and bioaccumulation in paddy soils:Insights from soil-derived dissolved organic matter)[J].环境科学学报（英文版）,2022(09):68-77

Porewater,maticity

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