Seasonal changes in total mercury and methylmercury in subtropical decomposing litter correspond to the abundances of nitrogen-fixing and methylmercury-degrading bacteria

文献类型： 外文期刊

第一作者： Yang, Liping

作者： Yang, Liping;Yang, Guang;Guo, Pan;Wang, Tao;Ma, Ming;Wang, Jueying;Xiong, Bingcai;Du, Hongxia;Ma, Ming;Wang, Dingyong;Du, Hongxia

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关键词： Litterfall decomposition; Methylmercury; Nitrogen-fixing microbes; MeHg-degrading microbes; Subtropical forest

期刊名称：JOURNAL OF HAZARDOUS MATERIALS （ 影响因子：12.2； 五年影响因子：11.9 ）

ISSN： 0304-3894

年卷期： 2023 年 442 卷

页码：

收录情况： SCI

摘要： Previous research has found total mercury (THg) and methylmercury (MeHg) levels increase with litterfall decay, thus suggesting litterfall decomposition plays an essential role in the biogeochemical transformation of mercury (Hg). However, it remains unclear how Hg accumulates in the decaying litter, how bacterial taxa networks vary and what roles various microorganisms play during litterfall decomposition, especially nitrogen (N)-fixing, MeHg-degrading and Hg-methylating microbes. Here, we demonstrated as degradation proceeded, a gradually -complex network evolved for litterfall bacteria for the subtropical mixed broadleaf-conifer (MBC) forest, whereas a relatively static network existed for the evergreen broadleaf (EB) forest. N-fixing and MeHg-degrading bacteria dominated throughout litterfall decomposition process, with relative abundances of N-fixing genera and nifH copies maximum and relative abundances of MeHg-degrading bacteria and merAB copies minimum in summer. Hence, N-fixing bacteria likely mediate THg increase in the decomposing litterfall, while MeHg enhancement may be regulated by aerobic MeHg-degrading microbes which can transform MeHg to inorganic divalent Hg(Hg2+) or further to elemental Hg (Hg0). Together, this work elucidates variations of N-fixing and MeHg-degrading microbes in decaying litterfall and their relationships with Hg accumulation, providing novel in-sights into understanding the biogeochemical cycle of Hg in the forest ecosystem.

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