State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
Sci Total Environ. 2024 Jun 20;930:172832. doi: 10.1016/j.scitotenv.2024.172832. Epub 2024 Apr 28.
Inorganic mercury (Hg) can be transformed into neurotoxic methylmercury (MeHg) by microorganisms in paddy soils, and the subsequent accumulation in rice grains poses an exposure risk for human health. Warming as an important manifestation of climate change, changes the composition and structure of microbial communities, and regulates the biogeochemical cycles of Hg in natural environments. However, the response of specific Hg methylation/demethylation to the changes in microbial communities caused by warming remain unclear. Here, nationwide sampling of rice paddy soils and a temperature-adjusted incubation experiment coupled with isotope labeling technique (Hg and MeHg) were conducted to investigate the effects of temperature on Hg methylation, MeHg demethylation, and microbial mechanisms in paddy soils along Hg gradients. We showed that increasing temperature significantly inhibited Hg methylation but promoted MeHg demethylation. The reduction in the relative abundance of Hg-methylating microorganisms and increase in the relative abundance of MeHg-demethylating microorganisms are the likely reasons. Consequently, the net Hg methylation production potential in rice paddy soils was largely inhibited under the increasing temperature. Collectively, our findings offer insights into the decrease in net MeHg production potential associated with increasing temperature and highlight the need for further evaluation of climate change for its potential effect on Hg transformation in Hg-sensitive ecosystems.
无机汞（Hg）可以在稻田土壤中的微生物作用下转化为神经毒性的甲基汞（MeHg），随后在稻米中的积累会对人类健康造成暴露风险。变暖作为气候变化的一个重要表现，改变了微生物群落的组成和结构，并调节了自然环境中 Hg 的生物地球化学循环。然而，特定的 Hg 甲基化/去甲基化对变暖引起的微生物群落变化的响应仍不清楚。在这里，我们通过全国范围的稻田土壤采样和温度调节的培养实验，并结合同位素标记技术（Hg 和 MeHg），研究了 Hg 梯度下温度对稻田土壤中 Hg 甲基化、MeHg 去甲基化和微生物机制的影响。结果表明，温度升高显著抑制了 Hg 甲基化，但促进了 MeHg 去甲基化。Hg 甲基化微生物相对丰度的降低和 MeHg 去甲基化微生物相对丰度的增加可能是导致这一结果的原因。因此，在升温条件下，稻田土壤中 Hg 的净甲基化产生潜力大大受到抑制。总的来说，我们的研究结果为与升温相关的净 MeHg 产生潜力的降低提供了新的见解，并强调需要进一步评估气候变化对 Hg 敏感生态系统中 Hg 转化的潜在影响。
