Long-range and regional transported size-resolved atmospheric aerosols during summertime in urban Shanghai

In this study, the concentrations of water soluble ions (WSI), organic carbon (OC), and elemental carbon (EC) of size-resolved (0.056-18μm) atmospheric aerosols were measured in July and August 2015 in Shanghai, China. Backward trajectory model and potential source contribution function (PSCF) model were used to identify the potential source distributions of size-resolved particles and PM_1.8-associated atmospheric inorganic and carbonaceous aerosols. The results showed that the average mass concentrations of PM_0.1, PM₁, and PM_1.8 were 21.21, 82.90, and 100.1μgm^-3 in July and 7.00, 29.21, and 35.10μgm^-3 in August, respectively, indicating that the particulate matter pollution was more serious in July than in August in this study due to the strong dependence of the aerosol species on the air mass origins. The trajectory cluster analysis revealed that the air masses originated from heavily industrialized areas including the Pearl River Delta (PRD) region, the Yangtze River Delta (YRD) region and the Beijing-Tianjin region were characterised with high OC and SO₄^2- loadings. The results of PSCF showed that the pollution in July was mainly influenced by long-range transport while it was mainly associated to local and intra-regional transport in August. Besides the contributions of anthropogenic sources from YRD and PRD region, ship emissions from the East China Sea also made a great contribution to the high loadings of PM_1.8 and PM_1.8-associated NO₃^-, NH₄⁺, and EC in July. SO₄^2- in Shanghai was dominantly ascribed to anthropogenic sources and the high PSCF values for PM_1.8-associated SO₄^2- observed in August was mainly due to the ship emissions of Shanghai port, such as Wusong port and Yangshan deep-water port. These results indicated that the particulate pollutants from long-range transported air masses and shipping made a significant contribution to Shanghai's air pollution.