Ozone and fine particle in the western Yangtze River Delta: An overview of 1 yr data at the SORPES station
This work presents an overview of 1 yr measurements of ozone (O-3) and\nfine particular matter (PM2.5) and related trace gases at a recently\ndeveloped regional background site, the Station for Observing Regional\nProcesses of the Earth System (SORPES), in the western part of the\nYangtze River Delta (YRD) in eastern China. Ozone and PM2.5 showed\nstrong seasonal cycles but with contrast patterns: O-3 reached a maximum\nin warm seasons but PM2.5 in cold seasons. Correlation analysis suggests\na VOC-sensitive regime for O-3 chemistry and a formation of secondary\naerosols under conditions of high O-3 in summer. Compared with the\nNational Ambient Air Quality Standards in China, our measurements report\n15 days of O-3 exceedance and 148 days of PM2.5 exceedance during the 1\nyr period, suggesting a severe air pollution situation in this region.\nCase studies for typical O-3 and PM2.5 episodes demonstrated that these\nepisodes were generally associated with an air mass transport pathway\nover the mid-YRD, i.e., along the Nanjing-Shanghai axis with its city\nclusters, and showed that synoptic weather played an important role in\nair pollution, especially for O-3. Agricultural burning activities\ncaused high PM2.5 and O-3 pollution during harvest seasons, especially\nin June. A calculation of potential source contributions based on\nLagrangian dispersion simulations suggests that emissions from the YRD\ncontributed to over 70% of the O-3 precursor CO, with a majority from\nthe mid-YRD. North-YRD and the North China Plain are the main\ncontributors to PM2.5 pollution in this region. This work shows an\nimportant environmental impact from industrialization and urbanization\nin the YRD region, and suggests an urgent need for improving air quality\nin these areas through collaborative control measures among different\nadministrative regions.