Wang Shuang, Pavuluri Chandra Mouli, Ren Lujie, Fu Pingqing, Zhang Yan-Lin, Liu Cong-Qiang
Institute of Surface-Earth System Science, Tianjin University Tianjin 300072 China
Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science and Technology Nanjing 10044 China.
RSC Adv. 2018 Nov 13;8(66):38108-38117. doi: 10.1039/c8ra06127k. eCollection 2018 Nov 7.
To understand the origins, secondary formation and seasonality of carbonaceous aerosols in North China, we collected PM samples on day- and night-time bases in summer and winter 2016 from a typical metropolis, Tianjin, and studied their carbonaceous components and stable carbon isotope ratios of total carbon (δC). PM ranged from 21.2 μg m to 74.8 μg m in summer and 25.3-816 μg m in winter. On average, organic carbon (OC) elemental carbon (EC) and water-soluble OC were found to be higher (3-5 times) in winter than that in summer. Secondary organic carbon that estimated by EC-tracer method was enhanced by a factor of 7 in winter compared to that in summer. δC showed a small enrichment of C (average -25.41 ± 0.34‰) in summer compared to that (-24.42 ± 0.44‰) in winter. Linear relations and mass ratios of selected carbonaceous components and δC imply that the carbonaceous aerosols in Tianjin were mainly derived from biomass burning emissions and photochemical processing in summer. In winter, coal combustion emissions and secondary formation of organics, including water-insoluble OC (WIOC), were dominant. This study warrants a need to understand the formation mechanisms of WIOC in the urban atmosphere and thus to reconcile the atmospheric models.
为了解中国北方碳质气溶胶的来源、二次形成及季节性特征，我们于2016年夏季和冬季，在白天和夜间采集了来自典型大都市天津的PM样本，并研究了其碳质成分及总碳稳定碳同位素比值（δC）。夏季PM浓度范围为21.2 μg/m³至74.8 μg/m³，冬季为25.3 μg/m³至816 μg/m³。平均而言，冬季有机碳（OC）、元素碳（EC）和水溶性OC含量比夏季高（3至5倍）。通过EC示踪法估算的二次有机碳在冬季比夏季增加了7倍。δC显示夏季相对于冬季（-24.42±0.44‰）有较小的¹³C富集（平均-25.41±0.34‰）。选定碳质成分与δC的线性关系及质量比表明，天津的碳质气溶胶夏季主要来源于生物质燃烧排放和光化学过程。冬季，煤炭燃烧排放以及包括水不溶性OC（WIOC）在内的有机物二次形成占主导。本研究有必要了解城市大气中WIOC的形成机制，从而完善大气模型。
