Department of Environmental Science and Analytical Chemistry (ACES) and Bolin Centre for Climate Research, Stockholm University, Stockholm, 10691, Sweden.
College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
Sci Rep. 2017 Sep 5;7(1):10422. doi: 10.1038/s41598-017-10766-4.
Wintertime East Asia is plagued by severe haze episodes, characterized by large contributions of carbonaceous aerosols. However, the sources and atmospheric transformations of these major components are poorly constrained, hindering development of efficient mitigation strategies and detailed modelling of effects. Here we present dual carbon isotope (δC and ΔC) signatures for black carbon (BC), organic carbon (OC) and water-soluble organic carbon (WSOC) aerosols collected in urban (Beijing and BC for Shanghai) and regional receptors (e.g., Korea Climate Observatory at Gosan) during January 2014. Fossil sources (>50%) dominate BC at all sites with most stemming from coal combustion, except for Shanghai, where liquid fossil source is largest. During source-to-receptor transport, the δC fingerprint becomes enriched for WSOC but depleted for water-insoluble OC (WIOC). This reveals that the atmospheric processing of these two major pools are fundamentally different. The photochemical aging (e.g., photodissociation, photooxidation) during formation and transport can release CO/CO or short-chain VOCs with lighter carbon, whereas the remaining WSOC becomes increasingly enriched in δC. On the other hand, several processes, e.g., secondary formation, rearrangement reaction in the particle phase, and photooxidation can influence WIOC. Taken together, this study highlights high fossil contributions for all carbonaceous aerosol sub-compartments in East Asia, and suggests different transformation pathways for different classes of carbonaceous aerosols.
东亚冬季深受严重雾霾的困扰，其主要特征是碳质气溶胶的大量贡献。然而，这些主要成分的来源和大气转化仍不清楚，这阻碍了制定有效的缓解策略和详细的效应建模。在这里，我们介绍了在 2014 年 1 月采集的城市（北京和上海的 BC）和区域受体（如戈桑韩国气候观测站）中黑碳 (BC)、有机碳 (OC) 和水溶性有机碳 (WSOC) 气溶胶的双碳同位素（δC 和 ΔC）特征。在所有地点，化石源（>50%）占主导地位，BC 主要来自于煤炭燃烧，而上海的最大来源则是液体化石燃料。在源到受体的传输过程中，δC 指纹对 WSOC 变得更丰富，而对水不溶性 OC（WIOC）则变得更贫化。这表明这两种主要成分的大气处理过程在根本上是不同的。形成和运输过程中的光化学老化（例如光解、光氧化）可以释放出 CO/CO 或更轻碳的短链 VOC，而剩余的 WSOC 则变得更加富含 δC。另一方面，一些过程，如二次形成、颗粒相中的重排反应和光氧化，会影响 WIOC。总的来说，这项研究强调了东亚所有含碳气溶胶亚成分中化石源的高贡献，并表明不同类型的碳质气溶胶具有不同的转化途径。
