大气细颗粒物中大分子有机质的化学特征与形成机制研究

The macromolecular organic matter are the major components of the fine aerosol and play important roles in the atmosphere, so it is very important to investigate the macromolecular organic matter in the fine aerosols. In this project, the chemical natures, sources, and formations of macromolecular organic matter in fine aerosols will be studied as follow: (1) the fractions of macromolecular organic matter include water soluble humic like substances (HULIS), alkaline soluble HULIS, humic acid, and non-extractable refractory carbon in the fine aerosols were isolated and investigated for their abundances, chemical compositions and structures. (2) the soot particles formed from the combustion of biomass residues and coal and top soil dusts were collected and characterized for different macromolecular organic fractions in these samples, thereby the relative contributions of primary sources of biomass burning, coal combustion, and soil dust were estimated. (3) the formation reactions of macromolecular organic matter in the aquatic systems were studied to investigate the contribution of secondary reactions in cloud water to macromolecular organic matter in the fine aerosols. This study are very helpful for us to understand the chemical compositions, structures, sources, and formation of macromolecular organic matter in the fine aerosols. The results would provide supports for establishment of the policy of atmospheric aerosol pollution control, prevention and treatment strategy.

大分子有机质是大气细颗粒物的重要组成部分，对其进行研究具有重要的科学意义。在本课题中，申请人拟从3个方面对大气细颗粒物中的大分子有机质进行研究：（1）对颗粒物样品中的大分子有机质进行定量分离和表征，弄清这些大分子有机质如水溶性类腐殖质、碱溶性类腐殖质、腐殖酸、不溶性有机质等在大气细颗粒物中的分布、化学组成和结构特征。（2）采集生物质和煤炭燃烧产生的黑碳颗粒和土壤样品，对样品中的大分子有机质组分进行分离和表征，初步了解一次燃烧来源和土壤尘土对大气颗粒物中有机质的影响和贡献。（3）液相条件下，对大分子有机质的形成机制进行研究，初步了解云水过程对大气颗粒中大分子有机质的贡献。最后通过综合对比分析，使我们对大气细颗粒物中的大分子有机质的组成、分布、化学特征等有比较全面的认识，同时也初步了解各有机质组分的来源组成，为有效地治理大气环境和制订污染物的排放政策提供理论基础和数据支持。

大分子有机质是大气细颗粒物的重要组成部分，对大气环境和气候等有着重要的影响。本课题主要针对大气细颗粒物中有机质的化学组成和光学特征、生物质和煤燃烧排放对大气有机质的影响以及液相条件下有机质的演化过程开展研究，取得的重要成果包括：1）通过对比研究，指出了当前大气HULIS分析方法存在的缺点，建立了用于大气HULIS研究的新方法；2）揭示了广州大气细颗粒物中大分子有机质的组成、化学特征和来源，阐明了大气有机质的含量、化学和吸光性的季节变化规律。3）通过对生物质和煤燃烧排放颗粒物中不同有机组分的系统分析，揭示了燃料类型和燃烧条件等对排放棕色碳的化学和吸光性质的影响，探讨了燃烧排放对大气环境中棕色碳的贡献。4）通过液相条件下的氧化反应，发现吸光性棕色碳组分在羟基自由基作用下呈现的主要是漂白作用。总的来说，本课题的研究使我们对大气细颗粒物中有机质的组成、性质、光学特征以及来源等比较全面的认识，也为政府制订合理的行之有效的大气颗粒物控制和防治策略提供了科学依据和数据支持。