Source apportionment of PM at urban and suburban areas of the Pearl River Delta region, south China - With emphasis on ship emissions.

Daily PM samples were collected at an urban site in Guangzhou in 2014 and at a suburban site in Zhuhai in 2014-2015. Samples were subject to chemical analysis for various chemical components including organic carbon (OC), element carbon (EC), major water-soluble inorganic ions, and trace elements. The annual average PM mass concentration was 48±22μgmand 45±25μgm in Guangzhou and Zhuhai, respectively, with the highest seasonal average concentration in winter and the lowest in summer at both sites. Regional transport of pollutants accompanied with different air mass origins arriving at the two sites and pollution sources in between the two cities caused larger seasonal variations in Zhuhai (>a factor of 3.5) than in Guangzhou (<a factor of 2.0). Positive matrix factorization (PMF) analysis identified six and five major source factors for PM in Guangzhou and Zhuhai, respectively. Ship emissions, a source factor previously ignored in making emission control policies in the Pearl River Delta region of south China, were among the top contributors to PM at both sites, accounting for >17% of PM mass concentrations.