Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York YO10 5DD, U.K.
Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K.
Environ Sci Technol. 2021 Jan 19;55(2):842-853. doi: 10.1021/acs.est.0c05689. Epub 2021 Jan 7.
The formation of isoprene nitrates (IsN) can lead to significant secondary organic aerosol (SOA) production and they can act as reservoirs of atmospheric nitrogen oxides. In this work, we estimate the rate of production of IsN from the reactions of isoprene with OH and NO radicals during the summertime in Beijing. While OH dominates the loss of isoprene during the day, NO plays an increasingly important role in the production of IsN from the early afternoon onwards. Unusually low NO concentrations during the afternoon resulted in NO mixing ratios of ca. 2 pptv at approximately 15:00, which we estimate to account for around a third of the total IsN production in the gas phase. Heterogeneous uptake of IsN produces nitrooxyorganosulfates (NOS). Two mono-nitrated NOS were correlated with particulate sulfate concentrations and appear to be formed from sequential NO and OH oxidation. Di- and tri-nitrated isoprene-related NOS, formed from multiple NO oxidation steps, peaked during the night. This work highlights that NO chemistry can play a key role in driving biogenic-anthropogenic interactive chemistry in Beijing with respect to the formation of IsN during both the day and night.
异戊二烯硝酸盐（IsN）的形成会导致大量的二次有机气溶胶（SOA）产生，并且它们可以作为大气氮氧化物的储存库。在这项工作中，我们估计了在夏季北京，异戊二烯与 OH 和 NO 自由基反应生成 IsN 的速率。虽然 OH 在白天主导异戊二烯的消耗，但从午后开始，NO 在生成 IsN 方面发挥的作用越来越重要。下午异常低的 NO 浓度导致大约 15:00 时的 NO 混合比约为 2 pptv，我们估计这约占气相中总 IsN 生成量的三分之一。IsN 的非均相吸收会产生硝基氧有机硫酸盐（NOS）。两种单硝化 NOS 与颗粒硫酸盐浓度相关，似乎是由连续的 NO 和 OH 氧化形成的。来自多次 NO 氧化步骤的二硝和三硝异戊二烯相关 NOS 在夜间达到峰值。这项工作强调了 NO 化学在驱动北京夏季白天和夜间的 IsN 形成过程中生物源-人为交互化学方面可以发挥关键作用。
