大气棕色碳老化过程及对气溶胶表面张力的影响机制研究

大气棕色碳不仅在紫外-可见光范围(UV-Vis)具有光吸收能力，而且它是具有亲水极性基团与憎水非极性基团的表面活性物质，可有效降低气液界面的表面张力，改变气溶胶的吸湿性和氧化性，进而影响云凝结核活化过程。本项目拟构建定量/定性产生不同类型的棕色碳进行老化过程的实验室模拟、并结合大气棕色碳老化过程中理化特征的外场观测的研究方法，拟探索棕色碳老化过程中其UV-Vis吸收光谱、组成结构、浓度粒径分布等特征的变化规律，以及对气溶胶表面活性物质分布的作用机制与贡献大小，并建立特征谱库；进而解析棕色碳分别通过改变表面活性物质以及溶质浓度对气溶胶表面张力的影响机制。研究成果将为研究气溶胶气液界面的化学过程提供基础科学依据。

Atmospheric brown carbon can absorb radiative energy in the ultraviolet-visible light band (UV-Vis). Besides, atmospheric brown carbon is a surface-active substance, containing both hydrophilic polar and hydrophobic non-polar groups, which can effectively reduce the surface tension at the gas-liquid interfaces, subsequently changing the hygroscopicity and oxidation of atmospheric aerosols, and affecting the activation of cloud condensation nuclei. This project aims to explore the evolution in its UV-Vis absorption spectrum, molecule structure, size-fractionated concentration during aging of atmospheric brown carbon as well as its impacts on aerosol surface-active substances. A methodology involving quantitative/qualitative lab experiments to produce various types of brown carbon and aging process, as well as field measurements of physicochemical properties of brown carbon during aging will be developed to establish a property database of atmospheric brown carbon. Furthermore, the mechanism and factors of brown carbon being both surface active substances and solute that affect aerosol surface tension will be investigated to provide a scientific basis for further research on the chemistry of aerosol gas-liquid interface.