三峡库区降水残留物的单颗粒气溶胶质谱研究

Aerosol participates cloud condense nuclei and precipitation, its insoluble residue returns to the surface with rainfall, providing insights into its chemical composition and sources. Our proposal aims to focus on the environmental sensitive Three Georges Dam Reservoir area, to investigate the chemical composition of precipitation residue using single particle mass spectrometry, and to find the connection between particulate pollution and its impact on precipitation in this area. The samples of precipitation and the corresponding ambient Particulate Matter will be collected at each site (Chongqing, Fuling, and Wanzhou) for two years, and then nebulized with a Collision nebulizer before Single Particle Aerosol Mass Spectrometer (SPAMS) analysis. The comparison between two kinds of samples will be conducted to remove the interference of the under-cloud removal of particulate matter. The spatial and temporal distribution will also be investigated. The detailed information of chemical composition and size distribution will be used to determine sources of precipitation residue by coupling with controlled simulation experiment of typical primary emissions. The implementation of this application will be useful to understand impacts of anthropogenic particulate pollution on precipitation and eco-system in the Three Georges Dam Reservoir area.

气溶胶参与成云降水形成过程，其不溶性残留物通过降水回到地面。降水残留物的化学组成可以推断其前体气溶胶的来源及其在成云、降水过程中的作用。本项目拟聚焦于环境敏感，生态脆弱的三峡库区，采用单颗粒气溶胶质谱方法确定降水残留物的组成和来源，评估大气气溶胶污染对三峡库区及周边降水的影响。拟收集三峡库区3个代表性采样点（重庆主城、涪陵、万州）的降水样品及降水过程中的大气颗粒物样品。样品经雾化，干燥后采用单颗粒气溶胶质谱仪进行（SPAMS）分析。通过对比降水和大气颗粒物样品中不溶性残留物的异同，排除气溶胶的云下去除组分，获得降水残留物的化学组成和粒径分布特征；通过比较不同采样点的分析结果，明晰其时空变化特征；通过对比降水残留物与典型源排放颗粒物样品中不溶物的组成特征，确定降水残留物的来源。本项目的实施可望准确评估人为气溶胶污染对三峡库区降水的影响，为治理大气污染，保护三峡库区脆弱的生态环境提供科学依据。

气溶胶参与成云降水形成过程，其不溶性残留物通过降水回到地面。降水残留物的化学组 成可以指示其前体气溶胶的来源及其在成云、降水过程中的作用。本项目拟聚焦于环境敏感、 生态脆弱的三峡库区，采用单颗粒质谱方法分析降水残留物的组成和来源，评估大气气溶胶污 染对三峡库区及周边降水的影响。拟收集三峡库区 3 个代表性采样点（重庆主城、涪陵、万州）的降水样品及其过程中的大气颗粒物样品，经雾化、干燥后采用单颗粒气溶胶质谱仪进行（SPAMS）分析。通过对比降水和颗粒物样品中残留物的异同，排除气溶胶云下去除过程的影响，获得降水残留物的化学组成和粒径分布的特征；通过比较不同采样点的分析结果，明晰其时空变化特征；通过对比典型源排放颗粒物样品中不溶物的相关特征，确定降水残留物的来源。明确其主要来源为：沙尘、背景尘、道路灰、建筑尘、生物质燃烧残余、土壤不溶物等。其中背景尘、建筑尘、道路灰等为3地的最重要的雨水不溶物来源，说明整体上三峡库区的降水过程有广泛的人为因素参与。本项目可理解人为气溶胶污染对三峡库区降水的影响，为针对性治理大气污染，保护三峡库区脆弱的生态环境提供科学依据。