Identification of key anthropogenic VOC species and sources controlling summer ozone formation in China

Abstract

Under the severe summer ozone pollution in China, differentiated identification of priority control objects according to the variety of regional contributing sources has become significant demand in formulating effective control measures. In this study, the monthly variations of anthropogenic volatile organic compound (VOC) emissions were evaluated based on source-specific temporal surrogates and further verified with widely referenced observation-based source apportionment results. Then, key summer ozone contributors were identified by developing the seasonal anthropogenic VOC emission inventories, updating localized industrial source profiles based on field measurements, and evaluating the pivotal VOC species and sources to form ozone. It is found that the remarkable anthropogenic VOC emissions in winter were mainly due to the intense coal and biomass burning for residential heating, especially in Northern China. Whereas the burning was relatively weak during summer. Areas with high propensities to form ozone were mainly distributed in the four major city clusters, North China Plain, Yangtze River Delta, Pearl River Delta, and Sichuan-Chongqing regions. To alleviate the ozone pollution in these regions, key species should be preferentially controlled during summer were given, such as m/p-xylene, ethene, and toluene, as well as key sources such as passenger cars, regionally differentiated chemical products manufacturing, surface coating, off-road machinery, and coking industry. The results will provide scientific direction for more effective and localized ozone control in China.