探讨冬季中国重污染城市气溶胶消光特性对化学成分的影响。
Exploring the impact of chemical composition on aerosol light extinction during winter in a heavily polluted urban area of China.
机构信息
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; University of Chinese Academy of Sciences, Beijing, 100049, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China.
出版信息
J Environ Manage. 2019 Oct 1;247:766-775. doi: 10.1016/j.jenvman.2019.06.100. Epub 2019 Jul 6.
An intensive measurement campaign was conducted in Xi'an, China from December 2012-January 2013 to investigate the chemical composition, formation, and optical properties of PM. The PM mass concentration (average = 138.8 ± 83.2 μg m) accounted for ∼50% of the PM mass. Organic aerosols (OA) and secondary inorganic aerosols (SIA) were the most abundant PM components, contributing 53.0% and 35.0% to the mass, respectively. Both primary emissions and aqueous-phase oxidation of secondary aerosols played roles in the pollution episodes. The average light scattering and absorption coefficients during the campaign were 805 ± 581 Mm and 123 ± 96 Mm, respectively. Both the mass scattering and mass absorption efficiencies for PM were higher than that for PM, indicating stronger ability of light extinction for the smaller particles at visible wavelengths compared with the larger ones. The contributions of aerosol species to light extinction coefficients under two visibility conditions were estimated based on multiple linear regression models, and the OA was found to be the largest contributor to light extinction in both cases. A larger contribution of SIA to light extinction for visibility <5 km demonstrated its greater impacts on visibility during heavy pollution conditions. These findings provide insights into the importance of submicron particles for pollution and visibility degradation in northwestern China.
在中国西安进行了一次密集的测量活动，时间为 2012 年 12 月至 2013 年 1 月，旨在研究 PM 的化学组成、形成和光学性质。PM 质量浓度（平均值=138.8±83.2μg/m3）占 PM 质量的约 50%。有机气溶胶（OA）和二次无机气溶胶（SIA）是 PM 中最丰富的成分，分别占质量的 53.0%和 35.0%。无论是一次排放还是二次气溶胶的水相氧化，都在污染事件中发挥了作用。在整个活动期间，平均光散射和吸收系数分别为 805±581Mm 和 123±96Mm。PM 的质量散射和质量吸收效率均高于 PM，这表明在可见光波长下，与较大颗粒相比，较小颗粒对光的消光能力更强。根据多元线性回归模型，估算了在两种能见度条件下气溶胶物种对消光系数的贡献，结果表明在两种情况下，OA 都是光消光的最大贡献者。对于能见度<5km 的情况，SIA 对光消光的贡献更大，表明在重污染条件下，SIA 对能见度的影响更大。这些发现为理解在中国西北地区亚微米颗粒对污染和能见度恶化的重要性提供了新的视角。
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