The impact of inland ship emissions on air quality

Despite the large number of domestic inland river vessels in China, information on inland river vessel emissions is very limited, because limited legislation exists for emission control and there is no monitoring infrastructure. Taking the Yangtze River in the region of Nanjing as research area, we compiled a ship emission inventory based on real-time information received from Automatic Identification System (AIS) signals and ship-related basic data provided by China Classification Society (CCS) database. The total estimated ship emissions in the Jiangsu section of the Yangtze River from September 2018 to August 2019 for NOx, SO2, PM10 and PM2.5 were 83.5, 41.8, 3.8 and 3.3 kton, respectively. These ship emissions were highest in the summer. From these estimates an inventory was constructed for ship emissions in the Yangtze River Delta (YRD) in Jiangsu. This ship emission inventory was compared with the Multi-resolution Emission Inventory for China (MEIC), the Shipping Emission Inventory Model (SEIM) and the satellite-derived emissions using the Daily Emissions Constrained by Satellite Observations (DECSO) algorithm. The result shows a consistent spatial distribution with riverine cities having higher NOx pollution than non-riverine cities. With this comparison we analyzed the relative impact of ship emissions on densely populated regions along the river. Inland ship emissions of NOx and SO2 are shown to contribute significantly, with each accounting for at least 40 %, to air pollution along the river.