Characteristics of PM_2.5 from ship emissions and their impacts on the ambient air: A case study in Yangshan Harbor, Shanghai

The rapid development of ports in China over the last two decades has had inevitable consequences on the ambient air quality in coastal areas and harbors. For mitigation strategies and monitoring aims, the contributions of ship emissions should be identified, especially in these specific areas. Therefore, in this study, fine particulate matters (PM_2.5) samples were collected at Yangshan Harbor in 2016 to characterize ship emissions and estimate their impacts on the ambient air. The results showed that the average annual PM_2.5 concentration was 44.02 μg/m³ at Yangshan Harbor. The mean seasonal PM_2.5 concentrations reached a maximum in the spring (60.28 μg/m³) and a minimum in the summer (28.04 μg/m³). Two methods were used in this study to estimate the contributions of ship emissions to the ambient air. When a V-based method was used, the primary estimated daily contributions of ship emissions to the ambient air at Yangshan Harbor ranged from 0.02 to 0.73 μg/m³ with an annual average of 0.10 μg/m³. When a PMF-based method was used, the contributions ranged from 0.02 to 9.15 μg/m³ with an annual average of 1.02 μg/m³. In fact, there was a significant underestimation of the true influences of ship emissions when only the primary contribution was considered. In accordance with this evidence, there was a main average underestimation of 1.84 μg/m³.