High-spatiotemporal-resolution ship emission inventory of China based on AIS data in 2014

Ship exhaust emissions have been considered a significant source of air pollution, with adverse impacts on the global climate and human health. China, as one of the largest shipping countries, has long been in great need of in-depth analysis of ship emissions. This study for the first time developed a comprehensive national-scale ship emission inventory with 0.005° × 0.005° resolution in China for 2014, using the bottom-up method based on Automatic Identification System (AIS) data of the full year of 2014. The emission estimation involved 166,546 unique vessels observed from over 15 billion AIS reports, covering OGVs (ocean-going vessels), CVs (coastal vessels) and RVs (river vessels). Results show that the total estimated ship emissions for China in 2014 were 1.1937 × 106 t (SO2), 2.2084 × 106 t (NOX), 1.807 × 105 t (PM10), 1.665 × 105 t (PM2.5), 1.116 × 105 t (HC), 2.419 × 105 t (CO), and 7.843 × 107 t (CO2, excluding RVs), respectively. OGVs were the main emission contributors, with proportions of 47%–74% of the emission totals for different species. Vessel type with the most emissions was container (~ 43.6%), followed by bulk carrier (~ 17.5%), oil tanker (~ 5.7%) and fishing ship (~ 4.9%). Monthly variations showed that emissions from transport vessels had a low point in February, while fishing ship presented two emission peaks in May and September. In terms of port clusters, ship emissions in BSA (Bohai Sea Area), YRD (Yangtze River Delta) and PRD (Pearl River Delta) accounted for ~ 13%, ~ 28% and ~ 17%, respectively, of the total emissions in China. On the contrast, the average emission intensities in PRD were the highest, followed by the YRD and BSA regions. The establishment of this high-spatiotemporal-resolution ship emission inventory fills the gap of national-scale ship emission inventory of China, and the corresponding ship emission characteristics are expected to provide certain reference significance for the management and control of the ship emissions.