The effectiveness of emission control policies in regulating air pollution over coastal ports of China: Spatiotemporal variations of NO_2 and SO_2

摘要

Air pollution over coastal port areas has become a major concern of today's world. As one of the largest shipping countries, China has issued a series of emission control policies to regulate air pollution in these areas. This study investigated the effectiveness of these policies by exploring the spatiotemporal variations of NO(2 )and SO2 in the five coastal port clusters i.e., Bohai Rim Area (BRA), Yangtze River Delta (YRD), Pearl River Delta (PRD), Southeast Coast (SEC) and Southwest Coast (SWC) of China from 2005 to 2020 using tropospheric NO2 and planetary boundary layer SO2 Vertical Column Densities (VCDs) retrieved from Ozone Monitoring Instrument (OMI). The NO2 levels were found to be the highest around 2011, whereas the SO2 levels showed decreasing trends after 2007, with rebounds found around 2011. BRA exhibited the highest average air pollution level compared to the other port clusters. PRD has implemented emission control policies earlier than the other port clusters, whereas YRD and BRA have controlled the NO2 and SO2 levels more effectively during 2010-2020. SWC saw an increase in the NO2 level during 2015-2020. As for individual ports, air pollution in Guangzhou port has been controlled most effectively during the entire study period; Qinhuangdao, Tangshan, Tianjin, Lianyungang, Qingdao and Rizhao have made great strides in reducing air pollution during 2010-2020. However, Beibu Gulf and Haikou showed clear increases in NO2 levels during 2018-2020 which may be attributed to strong growth in cargo throughput. Findings from this study can potentially help different authorities evaluate their effectiveness of air pollution control actions and support their future decision making.