Source apportionment of PM2.5 pollution in an industrial city in southern China

Abstract: Severe PM 2.5 pollution has become a great challenge to atmospheric pollution control in China. Most of previous aerosol source apportionment studies in China focused only on part of PM 2.5 (e.g., organic matter in composition or PM 1 in size) or lacked source contributions identified with necessary tempo-spatial variations, which makes the results not convincible enough for policy making. In this study, five various sites were selected for simultaneous PM 2.5 observation in an industrial city in the Pearl River Delta (PRD) of South China during all four seasons of 2014. A positive matrix factorization (PMF) model was applied to the datasets of measured chemical species to perform source apportionment with the results as: (1) The annual mean PM 2.5 concentration was 53 μg/m 3 , with vehicle emissions, secondary sulfate, biomass combustion, and secondary organic aerosol (SOA) identified as the major sources, contributing 21%, 20%, 11%, and 10% to PM 2.5 , respectively. Ship emissions, fugitive dust, secondary nitrate, industrial emissions, and coal burning each contributed 5%–8%. (2) The tempo-spatial variations of sources reveal that secondary sulfate, biomass combustion, SOA, and ship emissions had obvious regional pollution characteristics; however, vehicle emissions, secondary nitrate, coal burning, fugitive dust, and industrial emissions showed obvious local emission characteristics. (3) The exceeding standard days (PM 2.5 >75 μg/m 3 ) appeared with secondary nitrate, SOA, and biomass burning increasing mostly in concentration, indicating that the relevant primary sources or precursor emissions should be controlled more strictly. This study highlights the importance of SOA in PM 2.5 pollution in China, which has been scarcely quantified for bulk PM 2.5 in the literature.