Research on trends and spatial distribution of vehicular emissions and its control measure assessment in the Yangtze River Delta, China, for 1999–2015

Multi-year inventories of vehicular emissions (CO, non-methane volatile organic compounds (NMVOC), NO_x, PM₁₀, CO₂, CH₄, N₂O, NH₃, and SO₂) for each city in the Yangtze River Delta were calculated based on emission factors using the COPERT IV model, as well as its the high spatial resolution characteristics were established using a geographic information system methodology. Results showed that vehicular pollutant emissions (CO, NMVOC, NO_x, PM₁₀, CO₂, CH₄, N₂O, NH₃, and SO₂) changed from 3081.47, 335.94, 293.78, 17.15, 32,349.74, 17.18, 0.97, 0.33, and 58.77 Gg in 1999 to 1268.21, 249.9, 885.59, 39.78, 215,787.4, 19.38, 3.75, 13.78, and 24.93 Gg in 2015, respectively. Among them, the vehicular emissions CO₂ and NH₃ increased significantly. The spatial distributions of pollutant emissions were rather unbalanced, with emissions being mainly concentrated in coastal areas (particularly along the Yangtze River, around Hangzhou Bay, and around Tai Lake) and in city centers (Shanghai, Nanjing, Suzhou, Wuxi, Hangzhou, and Ningbo). Based on the vehicular emission inventories, the effects of implementing vehicular emission reduction strategies were assessed. The results show that it is very important to implement more stringent emission standards as early as possible, but other control measures are also essential to future vehicular emission mitigation.