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Suppression of anthropogenic secondary organic aerosol formation by isoprene
npj Climate and Atmospheric Science ( IF 9 ) Pub Date : 2022-02-09 , DOI: 10.1038/s41612-022-00233-x
Kangwei Li 1, 2, 3 , Chunmei Geng 1 , Wen Yang 1 , Zhipeng Bai 1 , Xin Zhang 2 , Chao Lin 2 , Linghong Chen 2 , Christian George 3 , Bin Zhao 4 , William J. Bloss 5 , Stephen White 6 , Merched Azzi 6 , Hai Yu 7
Affiliation  

Secondary organic aerosol (SOA) represents a major fraction of atmospheric fine particles. Both biogenic and anthropogenic volatile organic compounds (VOCs) can contribute to SOA through (photo-) oxidation. However, the current understanding of their combined, interactive effect on SOA formation and composition is still limited, challenging the accuracy in assessing global SOA budget, sources, and climate effect. Here we combine laboratory experiments and modelling to show that isoprene can suppress SOA formation from photo-oxidation of anthropogenic aromatics (toluene and p-xylene) with the presence of NOx, and similar SOA suppression phenomena are observed when replacing isoprene with propene. We find that the decreased SOA in such mixed-VOC conditions can be largely attributed to OH scavenging effect, resulting in reduced consumption of parent aromatics. However, various changes in SOA oxidation state (i.e., O/C) and oxidation pathways (i.e., more carbonyls formation) are observed following addition of isoprene, and the SOA chemical composition may not be similar to any single parent hydrocarbon, which implies the existence of complex interactions between the degradation chemistry for alkenes and aromatics. Under the conditions of this work, the OH scavenging effect is largely determined by gas-phase chemistry, which is expected to be widespread in binary or more complex systems in ambient air. More broadly, we infer that the global budget of anthropogenic SOA and its corresponding radiative forcing could be affected by biogenic emission of isoprene, particularly in urban environments with appreciable vegetation coverage.



中文翻译:

异戊二烯抑制人为二次有机气溶胶的形成

二次有机气溶胶 (SOA) 代表了大气细颗粒的主要部分。生物源和人为挥发性有机化合物 (VOC) 都可以通过(光)氧化促进 SOA。然而,目前对它们对 SOA 形成和组成的综合互动影响的理解仍然有限,这对评估全球 SOA 预算、来源和气候影响的准确性提出了挑战。在这里,我们将实验室实验和建模相结合,表明异戊二烯可以抑制在 NO x存在的情况下人为芳烃(甲苯和对二甲苯)的光氧化形成 SOA, 并且在用丙烯代替异戊二烯时观察到类似的 SOA 抑制现象。我们发现,在这种混合 VOC 条件下 SOA 的降低主要归因于 OH 清除效应,从而导致母体芳烃的消耗减少。然而,在添加异戊二烯后观察到 SOA 氧化态(即 O/C)和氧化途径(即形成更多羰基化合物)的各种变化,并且 SOA 化学组成可能与任何单一母体烃都不相似,这意味着烯烃和芳烃的降解化学之间存在复杂的相互作用。在这项工作的条件下,OH 清除效果在很大程度上取决于气相化学,预计气相化学将广泛存在于环境空气中的二元或更复杂的系统中。更广泛地,

更新日期:2022-02-09
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