大气汞均相和非均相化学反应过程研究进展

A review of homogeneous and heterogeneous reactions of atmospheric mercury

作为环境中汞传输的最重要通道,大气在汞的全球生物地球化学循环和传输扩散中起着极其关键的作用.大气环境成分复杂,汞在随大气环境传递过程中会经历复杂的化学反应,并导致不同形态之间相互转化,这也成为影响大气汞远距离传输尺度的关键因素.本文主要对大气汞在不同相界面之间的分配过程和主要影响因素(包括相界面的物理化学性质和外部环境条件等)进行了总结;对大气Hg0主要氧化反应过程(卤族元素氧化和O_3、OH·氧化)进行了阐述;对大气Hg^(2+)还原反应过程,尤其是光致还原反应等进行了梳理.如何综合运用野外监测分析和室内模拟等,利用微观分子表面分析等新技术明确大气汞均相、非均相反应过程,并将反应机理与大气汞传输过程模拟系统融合,将是未来大气汞研究的重要内容之一.

As the main route of long-range transport, atmosphere plays an important role in the biogeochemical cycle of mercury. The atmospheric chemical properties vary a lot during mercury transportat, leading to conversions among GEM, RGM and PBM. The conversions have significant influences on the processing and fate of mercury in the atmosphere. In this paper, the recent findings about the chemical reactions of atmospheric mercury were reviewed, such as the portioning of mercury between different interfaces, the oxidation reactions of Hg~ and reduction reactions of Hg2＋. These findings could be helpful for the description of environmental behavior of atmospheric mercury, the clarification Of chemical conversion rates of atmospheric mercury under various environmental conditions, and the precise estimation of residence time of atmospheric mercury. The homogeneous and heterogeneous reactions of atmospheric mercury could be identified by using new technologies, laboratory analysis and field monitoring. It could be an important content to combine the reaction mechanisms and long-range transport modeling in the atmospheric mercury study in the future.