Sulfur-driven methylmercury production in paddies continues following soil oxidation

作     者：Wenli Tang Chao Tang Pei Lei Wenli Tang;Chao Tang;Pei Lei

作者机构：School of the EnvironmentState Key Laboratory of Pollution Control and Resource ReuseNanjing UniversityNanjing 210023China School of EnvironmentNanjing Normal UniversityNanjing 210023China 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2022年第34卷第9期

页      面：166-174页

核心收录：

学科分类：082803[工学-农业生物环境与能源工程] 08[工学] 0828[工学-农业工程] 0818[工学-地质资源与地质工程] 0903[农学-农业资源与环境] 0703[理学-化学] 

基　　金：the financial support from the Natural Science Foundation of Jiangsu Province (Nos. BK 20190319 , BK20200322 ) the National Natural Science Foundation of China (No. U2032201 )。 

主　　题：Mercury Sulfur Availability Mercury methylation Rice 

摘      要：Methylmercury(MeHg) production in paddy soils and its accumulation in rice raise global concerns since rice consumption has been identified as an important pathway of human exposure to MeHg. Sulfur(S) amendment via fertilization has been reported to facilitate Hg methylation in paddy soils under anaerobic conditions, while the dynamic of S-amendment induced MeHg production in soils with increasing redox potential remains unclear. This critical gap hinders a comprehensive understanding of Hg biogeochemistry in rice paddy system which is characterized by the fluctuation of redox potential. Here, we conducted soil incubation experiments to explore MeHg production in slow-oxidizing paddy soils amended with different species of S and doses of sulfate. Results show that the elevated redox potential(1) increased MeHg concentrations by 10.9%-35.2%, which were mainly attributed to the re-oxidation of other S species to sulfate and thus the elevated abundance of sulfatereducing bacteria, and(2) increased MeHg phytoavailability by up to 75% due to the reductions in acid volatile sulfide(AVS) that strongly binds MeHg in soils. Results obtained from this study call for attention to the increased MeHg production and phytoavailability in paddy soils under elevated redox potentials due to water management, which might aggravate the MeHg production induced by S fertilization and thus enhance MeHg accumulation in rice.