VOCs concentration, SOA formation contribution and festival effects during heavy haze event: a case study in Zhengzhou, Central China

Abstract

Abstract In this study, online ambient volatile organic compounds (VOCs) were collected at an urban site of Zhengzhou in Central China during February 2018. The VOCs characteristics, source contributions and the Chinese New Year (CNY) effects have been investigated. During the sampling period, three haze periods have been identified, with the corresponding VOCs concentrations of 92 ppbv, 62 ppbv and 83 ppbv; in contrast, the concentration during non-haze days was found to be 57 ppbv. In addition, the festival effects of the Chinese New Year (CNY) were investigated, and the concentration of particulate matter precursor decreased significantly. Meanwhile, firework displaying events were identified, by the emission intensity had been greatly changed. Both potential source contribution function (PSCF) and the concentration weighted trajectory (CWT) models results indicated that short-distance transportation was the main influencing factor of the local VOCs pollution, especially by transport from the northeast. Source contributions results by the positive matrix factorization (PMF) model showed that vehicle exhaust (24%), liquid petroleum gas and natural gas (LPG/NG, 23%), coal combustion (21%), industrial processes (16%), and solvent usages (16%) were the major sources of ambient VOCs. Although industry and solvents have low contribution to the total VOCs, their SOA contribution were found to be relatively high, especially in haze-1 and haze-3 periods. The haze-2 period had the lowest SOAp during the sampling period, this is mainly caused by to the reduction of industrial and solvent emission due to CNY.