Investigation of dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and volatile organic compounds at the Yellow River Delta, northern China during summer: Contributions of anthropogenic hydrocarbons to secondary organic aerosols

Abstract

Total suspended particulate (TSP) and air samples were collected at Yellow River Delta (YelRD) in summer 2016 to analyze the concentrations of diacids and related secondary organic aerosols (SOA) and volatile organic compounds (VOCs). 37 organic components (dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids) and 40 VOCs were analyzed. Most of the dicarboxylic acids showed a similar diurnal variation characteristic with a slightly higher concentration during the daytime than nighttime. Oxalic acid (C2) was the species with the highest contribution to the total dicarboxylic acids, followed by succinic acid (C4), phthalic acid (Ph), and malonic acid (C3). The concentration of total VOCs in YelRD was lower than that in some urban areas in China, alkanes were the dominant component. The oxidation of anthropogenic aromatics to dicarboxylic acids and related SOA is also likely in YelRD. Source apportionment by positive matrix factorization (PMF) revealed that biogenic emissions, diesel exhaust, and oil volatilization, vehicular emissions, coal combustion, and secondary oxidation were the most important sources of organic species and VOCs in YelRD. This study provides potential insights into the characteristics of dicarboxylic acids and related SOA formed from VOCs oxidation in YelRD.