Characteristics and Sources of Atmospheric Volatile Organic Compounds Pollution in Summer in Chengdu

Abstract

In the research, volatile organic compounds (VOCs) were observed online in urban areas of Chengdu to study VOC concentration level, change characteristics, ozone generation contribution (OFP), and source contribution from June to September 2019. The results showed that the average concentration of TVOCs (total volatile organic compounds) was 112.66 μg·m-3, with alkanes (29.51%) and halogenated hydrocarbons (23.23%) forming the main components. The diurnal peak in VOCs mainly occurred from 10:00 am to 11:00 am, which is affected by urban motor vehicles, oil or gas volatilization, and industrial emissions. For OFP contribution of VOCs in summer, the contribution rate of aromatic hydrocarbons (42.7%) was the highest, followed by alkenes (27.4%). The key active species were m/p-xylene, ethylene, propylene, o-xylene, isopentane, cyclopentane, and acrolein. According to the source analysis by the PMF model, mobile sources are the main contributors of VOCs in summer in Chengdu, contributing 34% to TVOCs, followed by industrial sources (17%), volatile oil and gas (14%), and solvent use and natural sources contributing 11% and 13%. Therefore, motor vehicle and industrial emissions are the key control sources of VOCs in Chengdu, although control of pollution sources such as solvent use and oil or gas volatilization cannot be ignored.