Mercury (Hg) contamination in paddy soils has attracted increasing attention due to the health risks of human exposure to methylmercury (MeHg) through rice ingestion. To safely utilize Hg-contaminated soil and effectively reduce total Hg (THg) and MeHg accumulation in rice grains and its exposure risks, two types of thiol-functionalized montmorillonites developed by covalent grafting (CG-Mt) and mechanochemical grafting (MG-Mt) were as amendments for remediation of Hg-contaminated paddy soil. Pot environment results suggested that CG-Mt and MG-Mt application to soil (0.1%–1%, ) significantly reduced the accumulation of total THg and MeHg in rice grains by 40.3%–61.9% and 43.9%–62.3%, with the acceptable daily intake and target hazard quotient value of MeHg reduction by 39.5%-65.1% and 40.7%-64.4%. Application of CG-Mt and MG-Mt decreased soil available Hg and MeHg by 14.6%–95.4% and 19.4%–71.1%, respectively, which are directly responsible for the inhibition of THg and MeHg accumulation in rice. Structural equation model revealed that the changes in Hg methylation and demethylation related functional genes , and indirectly determined THg and MeHg level in rice. In view of the stabilized soil pH, enhanced enzyme activities and less disturbance in bacterial community, MG-Mt is a promising soil amendment for mitigating THg and MeHg exposure risks of rice produced from Hg-contaminated paddy soils.

中文翻译：

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硫醇功能化蒙脱石修复汞污染水稻土的性能、机理及环境效应评价


由于人类通过摄入大米接触甲基汞 (MeHg) 存在健康风险，稻田土壤中的汞 (Hg) 污染引起了越来越多的关注。为了安全利用汞污染土壤，有效降低水稻籽粒中总汞（THg）和甲基汞的积累及其暴露风险，通过共价接枝（CG-Mt）和机械化学接枝（MG-Mt）开发了两种硫醇功能化蒙脱石。作为修复汞污染稻田土壤的改良剂。盆栽环境结果表明，土壤施用CG-Mt和MG-Mt（0.1%~1%，）可显着降低稻粒中总THg和MeHg的积累量，分别为40.3%~61.9%和43.9%~62.3%，甲基汞每日可接受摄入量和目标危险商值分别减少39.5%-65.1%和40.7%-64.4%。施用CG-Mt和MG-Mt使土壤有效汞和甲基汞分别降低14.6%~95.4%和19.4%~71.1%，这直接导致了水稻THg和MeHg积累的抑制。结构方程模型揭示了Hg甲基化和去甲基化相关功能基因的变化，间接决定了水稻中THg和MeHg的水平。鉴于稳定的土壤 pH 值、增强的酶活性和较少的细菌群落干扰，MG-Mt 是一种很有前途的土壤改良剂，可用于减轻汞污染水稻土生产的水稻的 THg 和 MeHg 暴露风险。