大气复合污染条件下降水（云雾、雨雪和露）甲基汞分布特征及来源研究

甲基汞具有超强生物富集性、是毒性最强的有机金属污染物。大气雨水存在明显浓度的甲基汞，但其来源和机制不清。在当前大气复合污染日益严峻，环境大气中挥发性/半挥发性有机污染物急剧增加的现实情形下，以及申请者已有观测发现城市大气颗粒物中富集高水平甲基汞的基础上，本项目拟在我国内陆大气复合污染严重地区开展气溶胶-云雾-雨雪-露水中甲基汞的综合研究，揭示各分量中甲基汞的分布规律和时空变化特征；结合有机小分子、有机酸、有机卤和有机硫等有机组分同步观测，分析不同大气复合污染情形下其与甲基汞相关变化规律；识别实际环境大气降水中汞甲基化的关键甲基供体，建立关键有机组分与大气降水各分量甲基汞浓度响应关系，探索降水富氧环境中甲基汞非生物来源；结合已有大气降水中甲基汞来源的认知，系统评估我国内陆大气复合污染条件下降水中甲基汞的主要来源，为未来汞循环模型发展、暴露风险评估及制定汞防控策略提供基础数据和理论参考。

Methylmercury (MeHg) is a highly toxic organic metal pollutant with tremendous bioaccumulation and biomagnification in food webs. A certain concentration level of MeHg in atmospheric precipitation were measured, and yet its source and formation mechanism are unclear. In the current, complex air pollution has become increasingly severe with a sharp enhancement of volatile/semi-volatile organic pollutants in the ambient atmosphere, and the observations from our research group found that high level of MeHg bound to atmospheric particles in urban area. In this context, this project will intend to further carry out comprehensive observations of MeHg in aerosol- cloud/fog -rain/snow- dew water at the inland area of China with severely complex air pollution. The objects of this project will 1) to reveal the distribution characteristics, and temporal and spatial variation of MeHg in atmospheric precipitation; 2) combined with the synchronous observations for organic components, the variation of MeHg and organic components will investigate in different atmospheric pollution situations; 3) to identify key methyl donors of Hg methylation in real atmospheric precipitation, and establish response relationship between critical organic components and MeHg concentration; 4) combined the existing knowledge of MeHg, the systematically assessment will conduct to the main sources of MeHg in atmospheric precipitation. These will provide basic dataset and theoretical references for the future development of mercury cycle models, exposure risk assessment and preventing mercury pollution.