Characteristics of the source apportionment of primary and secondary inorganic PM2.5 in the Pearl River Delta region during 2015 by numerical modeling

Abstract

Fine particulate matter (PM2.5) contains both primary and secondary components, and their source apportionment characteristics in the Pearl River Delta (PRD) region during 2015 were compared by applying an air quality model coupled with an on-line tracer-tagged module. The results of contributions from different source regions to primary PM2.5 (PPM2.5) and secondary inorganic PM2.5 (SIPM2.5) in four selected cities show that the effect of regional transport on the SIPM2.5 level is stronger than that on the PPM2.5 level in the PRD region. For both Guangzhou city and the average of the entire PRD region, the industrial (25–40%) and transportation (20–25%) sectors are major sources of PPM2.5 and SIPM2.5. However, the residential sector contributes approximately 25% to the PPM2.5 level, mainly from residential biomass burning, but accounts for only approximately 10% of the SIPM2.5 level. The relative importance of each sector to the contributions from local and regional transport indicates that industrial emissions appear to lead to regional air pollution, while the transportation emissions seem to mainly affect the local and surrounding areas. Considering the impact of regional contributions to air quality, efforts made to reduce emissions in each city could not only improve the local air quality but also benefit downstream regions. To further decrease the PM2.5 level, the local government of each city in the PRD region should not only continue to strengthen the control of local emissions, such as those from transportation and residential biomass burning, but also increase their focus on regional joint prevention and control strategies with upstream area (such as northern Guangdong Province, and Jiangxi, Fujian and Hunan provinces).