Characteristics, source analysis and chemical reactivity of ambient VOCs in a heavily polluted city of central China

Abstract

From 2020.8.21 to 2020.9.30, continuously atmospheric volatile organic compounds (VOCs) were measured in the Central Plain to analyze the pollution characteristic, source distribution, chemical reactivity, and contribution to the formation of O3. The concentration of total VOCs (TVOC) was 29.47 ± 13.78 ppbv, and the main VOCs component was alkanes (46%). Ethane, propane, and n-butane were the first three species of VOCs. Six emission sources were identified through positive matrix decomposition (PMF) model, including biogenic source (4%), vehicle emission (28%), fuel evaporation (7%), industrial source (27%), solvent usage (23%) and combustion (11%). Backward trajectory analysis showed that VOCs were mainly derived from short-distance air masses (51%) traveling southeast of Zhengzhou, with the average mixing ratio of VOCs was 31.87 ppbv. Through the potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models, Zhengzhou and its surrounding areas are the main potential sources areas of VOCs. Finally, results of the OH radical loss rate (LOH) and ozone formation potential (OFP) showed that alkenes and aromatics were the species with highest chemical activity, of which both LOH was 34%, and aromatics contributes the most to the formation of O3, accounting for 49%. In addition, solvent usage, industrial source, and vehicular emission were important sources to OFP.