Source apportionments of atmospheric volatile organic compounds in Nanjing, China during high ozone pollution season

Abstract Atmospheric volatile organic compounds (VOCs) are not only harmful to human health, but also lead to ozone (O3) formation. From July 3 to August 1 of 2018, online measurements of atmospheric VOCs were conducted in Nanjing City, in order to investigate the source apportionments to VOCs since the Empirical Kinetic Modelling Approach (EKMA) suggested that O3 formation was VOC-limited at the receptor site. Using positive matrix factorization (PMF) model, we quantified eight sources of VOCs, including vehicle exhausts (23%), industrial source (18%), fuel evaporation (17%), petrochemical industry (12%), solvent usage (12%), biogenic emission (8%) and liquefied petroleum gas (7%) along with gasoline additive (3%). The diurnal distributions showed that the contributions of traffic-related sources maximized during the traffic rush hours. In contrast, biogenic sources had the highest contribution at noontime. Backward trajectory results showed that local traffic emissions were the main sources of VOC in Nanjing. Our results revealed that strict control of VOC emissions from local vehicle exhaust might be an important way to decrease high VOC pollution in Nanjing.