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 poten-tial(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 sulfate-reducing bacteria,and(2)increased MeHg phytoavailability by up to 75％due to the reduc-tions 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.

Wenli Tang;Chao Tang;Pei Lei

School of the Environment,State Key Laboratory of Pollution Control and Resource Reuse,Nanjing University,Nanjing 210023,China;School of Environment,Nanjing Normal University,Nanjing 210023,China

环境科学学报（英文版）

[1]Wenli Tang;Chao Tang;Pei Lei-.Sulfur-driven methylmercury production in paddies continues following soil oxidation)[J].环境科学学报（英文版）,2022(09):166-174

Methylmercury,phytoavailability

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