硫酸盐还原菌对单质汞氧化和甲基化作用机制研究

Microorganisms play key roles in the biogeochemical cycling of mercury, but the knowledge of the interactions bewteen microorganisms and mercury is still deficient. In this study, we select some typical sulfate-reducing bacteria (SRB)，including mercury methylators and nonmethylators, to explore the transformations of elemental mercury, Hg(0), by anaerobic microorganisms. The oxidation and methylation kinetics of Hg(0) by these anaerobic microorganisms will be examined systematically, and the environmental factors that may influence these reactions will be studied. Furthermore, using the mercury stable isotope tracer technique, the reaction kinetics of oxidation, reduction, methylation and demethylation of mercury by microorganisms will be exmamined. This study is the first time to investigate the transformations of Hg(0) by anaerobic microorganisms. It sheds additional light on bacteria-mercury interactions in controlling mercury transformations and distributions, and thus has important implications to the overall geochemical cycling of mercury in the environment.

微生物在汞的生物地球化学循环转化过程中起着极其重要的作用，但是目前相关方面的研究还很匮乏。本项目选择具有代表性的、与汞的甲基化作用关系密切的硫酸盐还原菌，研究它们在厌氧条件下对单质汞(Hg(0))的形态转化作用。测定这些微生物对Hg(0)的氧化和甲基化速率，并明确影响微生物对Hg(0)的氧化和甲基化作用的主要环境因子。同时，利用汞同位素示踪技术，示踪微生物对汞的迁移转化过程，测定硫酸盐还原菌对汞的氧化、还原、甲基化和去甲基化速率，探讨微生物对Hg(0)的氧化和甲基化作用机理。这是首次研究厌氧微生物对Hg(0)的形态转化作用。本项目的开展将开拓汞的生物地球化学循环的研究新思路，有利于完善汞的生物地球化学循环途径，最终为减少汞的长期、潜在的健康风险提供理论和技术支持。