复合污染条件对沿海大气汞形态分布和多相转化的影响研究

大气汞的形态和转化过程深刻影响汞的全球地球化学循环。我国华北沿海地区受大气复合污染、人为源汞排放和海洋大气化学等多方面共同影响，大气汞的形态分布和多相转化过程复杂，但具体机制不明。本项目拟选择华北沿海站点开展分形态大气汞的长期在线观测，研究复合污染条件下沿海大气汞的形态分布和日变化规律，分析其控制因素；利用特征化合物示踪法、正交矩阵因子分解和潜在源区分布函数等方法，解析各形态大气汞的来源和传输过程；基于详细的大气气相、液相和非均相化学机理，构建大气汞多相化学箱模型，研究复合污染-海洋大气相互作用下影响沿海大气汞多相转化的关键大气成分和化学过程。本项目的实施对于深入认识人为活动和海洋环境共同影响下，大气氧化性的改变对沿海边界层大气汞循环和沉降生态风险的影响具有重要科学意义。

Speciation and transformation of atmospheric mercury (Hg) significantly influence the global geochemical cycling of Hg. Complex air pollution, anthropogenic emissions and marine atmospheric chemistry usually co-exist in the coastal area of North China, leading to knowledge gaps of the distribution and transformation of atmospheric Hg speciation there. In the study we plan to conduct field observations of speciated atmospheric Hg at a typical coastal site in North China to study their speciation distribution and diurnal variations, as well as the driving factors. Tracers, PMF and PSCF methods will be employed to identify and quantify the contributions of emission sources and transport. We will develop a multiphase chemical box model based on the detailed atmospheric gas-, aqueous- and heterogeneous-phase chemical mechanisms to elucidate the important role of critical air pollutants and chemical processes in atmospheric Hg speciation transformation under the interactions between complex air pollution and marine atmosphere. The results are of great scientific significance for better understanding the atmospheric Hg cycling in polluted coastal marine boundary layer with changing atmospheric oxidizing capacity and will also help to improve the accurate evaluation of the ecological risk of atmospheric Hg deposition under the influence of both human activity and marine atmosphere.