Characteristics and sources of volatile organic compounds during summertime in Tai'an, China

Abstract

Continuous measurements of volatile organic compounds (VOCs) were conducted at an urban site in Tai'an, Shandong province of China from 15 May to 10 June 2019. The concentration of total VOCs (TVOCs) was 28.73 ± 15.20 ppbv, and oxygenated VOCs (OVOCs) comprised the dominant proportion (46.4%) among five VOC groups. The most abundant VOC species was formaldehyde, followed by propane, ethane, acetaldehyde, acetone and ethylene. Six VOC sources were identified by positive matrix factorization (PMF) model, including coal combustion (26.2%), OVOCs-related source (20.2%), liquefied petroleum gas (LPG) usage (18.9%), vehicle emission (17.1%), biogenic source (11.1%) and solvent usage (6.5%). The results of conditional bivariate probability function (CBPF) showed that LPG usage, vehicle exhaust and solvent usage were mainly affected by local emissions, while other three sources were greatly affected by regional transmission. Based on the China Ambient Air Quality Standard, O3 episode and non-O3 episode days were identified, and the concentrations of TVOCs were 32.80 ± 15.78 ppbv (O3 episode days) and 24.01 ± 14.47 ppbv (non-O3 episode days), respectively. During different O3 pollution episodes, OVOCs contributed the highest proportion to VOC concentration and ozone formation potential (OFP), while aromatics contributed the greatest potential for secondary organic aerosol potential (SOAP). Moreover, coal combustion and LPG usage were significantly associated with the increase in VOC pollution on O3 episode days.