VOC characteristics, chemical reactivity and sources in urban Wuhan, central China. (1st March 2020) - Hui, Lirong
Abstract: This paper presents the pollution levels, variation characteristics, chemical reactivity, source apportionment and potential source regions of 102 volatile organic compounds (VOCs) observed from 2017.4.26 to 2017.6.6 in urban Wuhan. The concentration of total VOCs (TVOCs) was 28.92 ± 20.10 ppbv, and the VOC composition was dominated by alkanes (51.14%). Propane, ethane and acetone were the most abundant VOC species. The results for the OH radical loss rate (LOH ) and ozone formation potential (OFP) indicated that alkenes were responsible for much of the chemical reactivity and O3 formation, accounting for 47.02% and 49.52%, respectively, and the dominant VOC species were mainly associated with anthropogenic sources, such as vehicle emissions, the use of natural gas (NG) and liquefied petroleum gas (LPG), solvent usage and fuel evaporation. Ambient ratio data showed that VOCs were greatly affected by the pollution sources (such as emissions of NG and LPG, liquid gasoline and fuel evaporation sources, vehicle exhaust emissions, and biogenic sources), photochemical reaction processes and regional transport. Industrial sources (11.84%), industrial sources + coal burning (13.09%), LPG/NG usage + solvent usage in painting/coating (37.28%), fuel evaporation (12.04%), vehicle exhaust (13.65%), biogenic sources (5.95%) and biomass burning (6.15%) were determined by positive matrix factorization (PMF). Furthermore, LPG/NG usage, solvent usage in painting/coating and vehicle exhaust were the most important VOC sources, and their various contributions were affected by a combination of factors, including the emission strength of pollution sources, meteorological conditions and photochemical reaction processes. Backward trajectory analysis showed that VOC pollution was mainly derived from the south via short-distance transport. The potential source contribution function (PSCF) results indicated that the main sources affecting VOC pollution were the potential sources to the south and local sources within the city. This study provides evidence for local governments to formulate VOC control strategies during the transition from spring to summer. Graphical abstract: Image 1 Highlights: Alkenes were the key components of chemical reactivity and O3 formation. The effects of sources, photochemical reactions and air mass on VOCs were analysed. LPG/NG usage, solvent usage in painting/coating and vehicle exhaust were important. Potential sources from the south and local sources within the city were important.