海洋型冰川雪冰中蓝细菌对微生物介导的汞甲基化过程的影响机理研究

冰川是全球重要的淡水资源库，但同时也是全球汞的“沉积池”。冰川上的无机汞在微生物的作用下可转变为生物危害更大的甲基汞。以往研究发现蓝细菌对汞的微生物甲基化作用有显著影响，蓝细菌是冰川上的主要微生物，但目前冰川中蓝细菌对微生物介导的汞甲基化的影响机理尚不清楚。我国海洋型冰川所处区域气温高，融化速度快，冰川上的环境对甲基汞生成更加有利，同时冰川下游地区人口稠密，生态系统面临的潜在汞污染威胁大，理解海洋型冰川上甲基汞的形成机制对分析冰川下游生态系统中甲基汞的危害水平至关重要。本项目拟对我国西南地区的五条海洋型冰川雪冰和融水中微生物及汞的研究，阐明海洋型冰川中甲基汞、汞甲基化微生物群落和蓝细菌群落结构的变化规律，解析雪冰中蓝细菌对汞甲基化微生物的影响，结合室内模拟实验，揭示蓝细菌对微生物介导的汞甲基化过程的影响机制，为预测冰川下游生态系统中甲基汞浓度和应对潜在威胁提供理论依据。

Glaciers are the most important global freshwater resources, while they are also mercury “sinks” on earth. Influenced by the activities of microorganisms, the inorganic mercury on glaciers can be methylated to form the compounds which are much harmful to organisms. Previous studies showed that cyanobacteria, dominated on glaciers, have a significant effect on the mercury methylation of microbes. However, the impact of cyanobacteria on microbes-mediated mercury methylation is still obscure. The domestic maritime glaciers geographically located in warm areas are melting rapidly, such environment is extremely suitable for the mercury methylation. Due to the dense population of the glaciated downstream regions, the downstream ecosystem is threatened by potential mercury pollution. It is critical for us to understand the mercury methylated mechanism for predicting the damage of methylmercury on the glaciated downstream ecosystem. Through analysis of microbiome and mercury species in snow, ice and melt water of five maritime glaciers in southwestern China, it is aimed to reveal the spatial variation rule of the methylmercury, mercury methylated microbial communities and cyanobacteria communities, investigate the impact of different cyanobacterial community on mercury-methylating process. Meanwhile, combining with the analysis of simulating lab test, the mechanism of cyanobacterial communities impacting on microbial mercury-methylating process will be clarified, similar as microorganisms in snow and ice contributing to the formation of methylmercury. These results will provide the scientific basis for predicting the concentration of methylmercury in the glaciated downstream ecosystem and responding to the potential threats.