School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
Sci Total Environ. 2020 Jul 10;725:138290. doi: 10.1016/j.scitotenv.2020.138290. Epub 2020 Apr 4.
Understanding the characteristics and sources of atmospheric chromophores is essential to assess their impact on climate change and the quality of atmospheric environment. In this work, the fine particulate matter (PM) samples of Xi'an, China in 2017 were analyzed by excitation-emission matrices and parallel factor analysis (EEM-PARAFAC) method to obtain the species, content, sources and seasonal variation characteristics of atmospheric chromophores. The results showed that humic-like (HULIS) chromophores and polycyclic aromatic hydrocarbons-like (PAHs-like) chromophores were the most abundant chromophores in the samples, accounting for 42% and 33%, respectively. With the aggravation of air pollution, the relative content of low-polarity chromophores increased markedly, while the relative content of polar chromophores decreased. The concentrations of atmospheric chromophores exhibited obvious seasonal variation characteristics: high in winter and low in summer. Similarly, the relative contributions of atmospheric chromophores from each source varied with the season. In addition, special weather and human activities had a significant influence on the source of atmospheric chromophores. Dust source was an important source of atmospheric chromophores, which was susceptible to long-range incoming air masses from northwestern regions in spring. However, the chromophores from the dust source were easily removed by wet precipitation, which was the same as the chromophores from the combustion source. The chromophores from the combustion source were susceptible to human activities. The contribution of combustion source to atmospheric chromophores was reduced due to the implementation of air pollution control policies during the Chinese Spring Festival. In summer, the formation of photochemical secondary chromophores was more significant than in other seasons, and the photochemical secondary chromophores increased due to the formation of liquid phase reactions under high relative humidity conditions.
了解大气生源色的特征和来源对于评估其对气候变化和大气环境质量的影响至关重要。本工作采用激发-发射矩阵和平行因子分析（EEM-PARAFAC）方法对 2017 年中国西安的细颗粒物（PM）样品进行分析，得到大气生源色的种类、含量、来源和季节变化特征。结果表明，腐殖质类（HULIS）生源色和多环芳烃类（PAHs-like）生源色是样品中最丰富的生源色，分别占 42%和 33%。随着空气污染的加剧，低极性生源色的相对含量明显增加，而极性生源色的相对含量则减少。大气生源色的浓度表现出明显的季节性变化特征：冬季高，夏季低。同样，各来源大气生源色的相对贡献也随季节而变化。此外，特殊天气和人类活动对大气生源色的来源有显著影响。沙尘源是大气生源色的重要来源，春季易受来自西北部地区的长距离输入空气团的影响。然而，沙尘源的生源色容易被湿沉降去除，这与燃烧源的生源色相同。燃烧源的生源色易受人类活动的影响。由于中国春节期间实施了空气污染控制政策，燃烧源对大气生源色的贡献减少。在夏季，光化学二次生源色的形成比其他季节更为显著，由于高相对湿度条件下液相反应的形成，光化学二次生源色增加。
