Suppression of mercury methylation in soil and methylmercury accumulation in rice by dissolved organic matter derived from sulfur-rich rape straw

文献类型： 外文期刊

第一作者： Zheng, Zhoujuan

作者： Zheng, Zhoujuan;Hu, Jie;He, Tianrong;Yin, Deliang;Zheng, Zhoujuan;Hu, Jie;He, Tianrong;Zhou, Xian;Yin, Deliang;Liu, Chengbin;Yin, Deliang

作者机构：

关键词： Rape straw; Dissolved organic matter; Mercury; Soil; Rice

期刊名称：ENVIRONMENTAL POLLUTION （ 影响因子：8.9； 五年影响因子：9.5 ）

ISSN： 0269-7491

年卷期： 2024 年 346 卷

页码：

收录情况： SCI

摘要： Straw amendment significantly enhances mercury (Hg) methylation and subsequent methylmercury (MeHg) bioaccumulation in Hg -contaminated paddy fields by releasing dissolved organic matter (DOM). This study comprehensively investigates the regulatory mechanisms of DOM and its different molecular weights derived from sulfur -rich rape straw (RaDOM) and composted rape straw (CRaDOM) applied in the rice -filling stage on soil MeHg production and subsequent bioaccumulation in rice grains. The results indicated that the amendment of RaDOM and CRaDOM significantly reduced soil MeHg content by 42.40-62.42%. This reduction can be attributed to several factors, including the suppression of Hg-methylating bacteria in soil, the supply of sulfate from RaDOM and CRaDOM, and the increase in the humification, molecular weight, and humic-like fractions of soil DOM. Additionally, adding RaDOM increased the MeHg bioaccumulation factor in roots by 27.55% while inhibiting MeHg transportation by 12.24% and ultimately reducing MeHg content in grains by 21.24% compared to the control group. Similarly, CRaDOM enhanced MeHg accumulation by 25.19%, suppressed MeHg transportation by 39.65%, and reduced MeHg levels in the grains by 27.94%. The assimilation of sulfate derived from RaDOM and CRaDOM into glutathione may be responsible for the increased retention of MeHg in the roots. Over the three days, there was a significant decrease in soil MeHg content as the molecular weight of RaDOM increased; conversely, altering the molecular weight of CRaDOM demonstrated an inverse trend. However, this pattern was not observed after 12 days. Applying sulfur -rich rape DOM can help mitigate MeHg accumulation in paddy fields by regulating the quality of soil DOM, sulfur cycling, and Hg-methylating bacteria.

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