Multifunctional Products of Isoprene Oxidation in Polluted Atmosphere and Their Contribution to SOA

Abstract Isoprene (2‐methyl‐1, 3‐butadiene) is a nonmethane volatile organic compound (VOC) with the largest global emission and high reactivity. The oxidation of isoprene is crucial to atmospheric photochemistry and contributes significantly to the global formation of secondary organic aerosol. Here, we conducted comprehensive observations in polluted megacities of Nanjing and Shanghai during summer of 2018. We identified multiple functionalized isoprene oxidation products, of which 72% and 88% of the total mole concentration were nitrogen‐containing species with the dominant compound being C5 dihydroxyl dinitrate (C 5 H 10 N 2 O 8 ). We calculated the volatility using the group‐contribution method and estimated the particle‐phase concentration by equilibrium gas/particle partitioning. The results showed that the multifunctional products derived from isoprene oxidation can contribute to 2.6% of the total organic aerosol mass (0.28 ± 0.27 μg/m 3 ), highlighting the potential importance of isoprene oxidation in polluted regions.