大气棕色碳来源与光学特征研究进展

An overview of the studies on sources and optical properties of atmospheric brown carbon

在碳质气溶胶的研究中,发现大气中存在的吸光性物质不只有黑碳(BC),部分有机碳(OC)在紫外-近可见波段也具有吸光能力,吸光部分呈棕色或棕褐色而被称为棕碳(BrC).综述了大气颗粒物中BrC的来源、化学组成与光学特征,以获得不同来源下BrC光学特征的差异.从来源看,BrC主要分一次来源和二次来源,不同源BrC光学特征也不同,化石燃料源的BrC吸光能力强于生物质燃烧源BrC,且有着更高的波长依赖性;从发色团组成来看,水溶性和非水溶性BrC中识别的发色团主要为类腐殖质、多环芳烃、类蛋白质和硝基芳香族化合物等.发色团被认为是决定BrC吸光特性的关键,这些发色团在300~400 nm波段的吸光贡献约为30%~70%.最后,阐述了BrC研究中存在的问题及今后的研究方向,并对BrC在光学的研究趋势和前景进行了展望.

In the study of carbonaceous aerosols,researchers found that not only black carbon(BC) exists in the atmosphere,but also some organic carbon(OC) in the ultraviolet-visible wavelength band,and the absorbing part is also called brown carbon(BrC) because of its brown or tan color.Based on the existing research,the sources,chemical composition and optical characteristics of BrC in atmospheric particulate matter are reviewed to obtain the differences in the optical characteristics of BrC under different sources.From the source point of view,BrC is mainly divided into primary source and secondary source,different sources of BrC optical characteristics are also different,fossil fuel source BrC light absorption capacity is stronger than biomass combustion source BrC,and has a higher wavelength dependence;from the perspective of chromophores,water-soluble and water-insoluble BrC identified chromophores are mainly humic-like substances,polycyclic aromatic hydrocarbons,proteins and nitro aromatic compounds,etc.Chromophores are considered the key to determine the light absorption characteristics of BrC,which contribute about 30%~70% to the absorbance of light in the 300~400 nm band.Finally,the problems existing in BrC research and future research directions are discussed,and the research trends and prospects of BrC in optics are prospected.