Xu Min, Hu Bo, Zhao Shuman, Yan Guangxuan, Wen Tianxue, Zhao Xiaoxi
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Sci Total Environ. 2024 Jun 1;927:172396. doi: 10.1016/j.scitotenv.2024.172396. Epub 2024 Apr 10.
Size-segregated aerosols collected in Beijing from 2021 to 2022 were used to investigate the contribution of organic aerosols to the aerosol liquid water content (ALWC), the influencing factors of ALWC, and the concentrations and size distribution characteristics of water-soluble organic carbon (WSOC) after clean air actions. The results showed that the concentration of WSOC in particulate matter (PM) was 3.52 ± 2.43 μg/m during the sampling period. Obvious changes were observed in the size distribution of WSOC after clean air actions, which may be attributed to the enhancement of atmospheric oxidation capacity and the decrease in PM concentration. The contribution of organic aerosols to the ALWC in fine PM was 18.1 % during the sampling period, which was more significant at lower particles concentration and smaller particle size ranges. The ambient relative humidity (RH) and the ratio of NO/SO had an apparent influence on ALWC. The continuous increase in the nitrate proportion significantly reduced the deliquescence point of the aerosols, making them prone to hygroscopic growth at lower RH. Analysis of the relation among nitrogen oxidation ratio (sulfur oxidation ratio), ALWC and PM mass concentrations suggests that organic matter has a significant effect on the formation of secondary inorganic aerosols in the initial phase of pollution formation and plays a crucial role in aerosol pollution formation in Beijing. These results are conducive to understanding the formation mechanism of aerosols and provide scientific data and theoretical support for the formulation of more effective emission-reduction measures.
利用2021年至2022年在北京采集的粒径分级气溶胶，研究了有机气溶胶对气溶胶液态水含量（ALWC）的贡献、ALWC的影响因素以及清洁空气行动后水溶性有机碳（WSOC）的浓度和粒径分布特征。结果表明，采样期间颗粒物（PM）中WSOC的浓度为3.52±2.43μg/m。清洁空气行动后，WSOC的粒径分布发生了明显变化，这可能归因于大气氧化能力的增强和PM浓度的降低。采样期间，有机气溶胶对细颗粒物中ALWC的贡献为18.1%，在较低颗粒物浓度和较小粒径范围内更为显著。环境相对湿度（RH）和NO/SO比值对ALWC有明显影响。硝酸盐比例的持续增加显著降低了气溶胶的潮解点，使其在较低RH下易于吸湿增长。对氮氧化率（硫氧化率）、ALWC和PM质量浓度之间关系的分析表明，有机物在污染形成初期对二次无机气溶胶的形成有显著影响，在北京气溶胶污染形成中起关键作用。这些结果有助于理解气溶胶的形成机制，为制定更有效的减排措施提供科学数据和理论支持。
