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Carbon isotopic signatures of carbonyls from roadside air observation
Journal of Atmospheric Chemistry ( IF 2 ) Pub Date : 2021-05-26 , DOI: 10.1007/s10874-021-09423-y
S.J. Guo

In this work, isotopic effects of carbonyls were evaluated during the simulation sampling of gaseous carbonyls by using a carbon isotope method developed, and then variation characteristics of carbon isotopic compositions were investigated for three dominant carbonyls including formaldehyde, acetaldehyde and acetone in the roadside air of Nanning for the first time. A small difference in δ13C values (0.04 to 0.50 ‰) were observed between the calculated and measured values of carbonyl-derivatives, indicating that the effect on carbon isotopic fractionation could hardly occurred in the simulation sampling of gaseous carbonyls. The roadside air measurements showed that \({\delta }^{13}\)C values of formaldehyde, acetaldehyde and acetone were –36.02 ‰ to –31.18 ‰, –35.35 ‰ to –32.01 ‰ and –30.45 ‰ to –29.09 ‰, respectively. Further correlation of the measured \({\delta }^{13}\)C values was good for formaldehyde, acetaldehyde and acetone (R2 = 0.6275–0.7755), indicating that their similar sources could be the direct vehicular emission or indirect productions from precursors such as hydrocarbons. Particularly, formaldehyde, acetaldehyde and acetone in the roadside air were all enriched in the early afternoon by round 0.5–6 ‰ in 13C compared to other sampling durations, which was likely due to the contributions from the positive photo-oxidation productions of hydrocarbons. Finally, it was found that all measured \({\delta }^{13}\)C values (–36.5 ‰ to –29.0 ‰) agreed with the forecasted \({\delta }^{13}\)C range (–43.0 ‰ to –26.0 ‰) according to the 13C mass balance of carbonyls and their precursors such as hydrocarbons, indirectly confirming such positive productions in the roadside air.



中文翻译:

从路边空气观测中发现羰基的碳同位素特征

在这项工作中,使用开发的碳同位素方法在气态羰基化合物的模拟采样过程中评估了羰基化合物的同位素效应,然后研究了路边空气中三种主要羰基化合物(包括甲醛,乙醛和丙酮)的碳同位素组成变化特征。南宁第一次。在δ小差13个羰基衍生物的计算值与实测值之间观察到C值(0.04〜0.50‰),这表明在碳同位素分馏效应几乎不能发生在气态羰基的模拟采样。路边空气测量显示\({\ delta} ^ {13} \)甲醛,乙醛和丙酮的C值分别为–36.02‰至–31.18‰,– 35.35‰至–32.01‰和–30.45‰至–29.09‰。测得的\({{delta} ^ {13} \) C值与甲醛,乙醛和丙酮的相关性 更好(R 2 = 0.6275–0.7755),表明它们的相似来源可能是直接的汽车排放或间接的产生。从碳氢化合物等前体中提取。特别是,与其他采样时间相比,路边空气中的甲醛,乙醛和丙酮在下午凌晨在13 C时都富集了0.5–6‰ ,这很可能是由于碳氢化合物的正光氧化产生所致。最后,发现所有测得的\({\ delta} ^ {13} \)根据羰基及其前体的13 C质量平衡,C值(–36.5‰至–29.0‰)与预测的\({{delta} ^ {13} \) C范围(–43.0‰至–2​​6.0‰)一致。例如碳氢化合物,间接证实了路边空气中这种积极的生产。

更新日期:2021-05-26
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