Real-time chemical characterization of single ambient particles at a port city in Chinese domestic emission control area - Impacts of ship emissions on urban air quality.

The domestic emission control area (DECA) policy has been implemented in China since 2017. However, its impact on ship emissions and in turn urban air quality is still unclear. In this study, real-time single particle measurements were carried out at a site in urban Guangzhou, about 1 km downwind of Huangpu Port, the largest maritime transport hub in southern China, in the summer of 2020 using a single particle aerosol mass spectrometer (SPAMS). During the campaign, the hourly averaged number fraction of ship emitted particles, using vanadium as a chemical indicator, varied from 0 to 14% with an average of 2 ± 1%. Ship emitted single particles contain organic carbon (OC), elemental carbon (EC), metals, sulfate and nitrate. More than 95% of ship emitted particles were sulfate-containing particles and the relative peak areas (RPAs) of sulfate and vanadium in the hourly average mass spectra of ship emitted particles were highly correlated (R = 0.85), suggesting the potential contribution of ship emissions to sulfate production in coastal cities. The relative abundance of OC and EC-related components in ship emitted particles varied and it was likely attributed to the different blending fluids used in the production of low sulfur fuels. The results from this study provide evidence for evaluating the effectiveness of the current regulations and guidance for future policy-making regarding the low sulfur fuel quality regulation and multiple-component control strategies.