Shipping emission inventories in China's Bohai Bay, Yangtze River Delta, and Pearl River Delta in 2018.

Pollutant emissions from ships could increase with expanding international trade and shipping fleet size, posing a severe but often overlooked threat to public health. China houses the three biggest port clusters in the world: the Bohai Bay (BB), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD) and must combat pollutant emissions. This study examines the emissions of key pollutants (i.e., NOX, PM10, PM2.5, HC, CO, SOX, CO2, NMVOC, and CH4) utilizing a bottom-up methodology with the aid of automatic identification system data. Our results show that among the three regions studied, ships in the YRD produce the most emissions, accounting for 47.84% of the combined total emissions in 2018. We evaluate the emissions from different ship types, operation modes, and discharge equipment. Container ships account for ~50% of all emissions, which are mainly generated during the cruising phase. Different power sources produce varying levels of pollutants owing to power, load, and discharge variations. In addition, ship emissions have seasonal characteristics, which are reflected by the decline trend recorded in February, July, August, and December. This baseline dataset could aid comparisons with historic or future emission data and help establish regulatory actions to improve air quality.