Preliminary Exploration into the Urban-suburban Differences in PM2.5 Pollution Characteristics and Their Causes in Yandu District
In order to investigate the differences in PM2.5 pollution characteristics between urban and suburban areas and their causes,the data on PM2.5 mass concentrations in urban and suburban areas of Yandu District in 2022 were used to analyze the differences in PM2.5 concentration levels and daily change characteristics between urban and suburban sites,and a preliminary investigation of the causes was carried out in terms of the sources of pollution and the effects of transmission.The annual average PM2.5 concentration in 2022 in suburban areas was higher than in urban areas,by 23.1％.The peak diurnal variation of PM2.5 concentration at suburban station was more prominent,and the peak morning concentration occurred around 06:00 am in spring,summer and autumn,which was significantly earlier than that at urban station.The PM2.5 characteristic component concentration ratios and Chemical Mass Balance(CMB)model simulation results showed that the contributing sources of PM2.5 at urban and suburban stations had similarities and specificities.The main contributing sources were mobile sources,coal combustion sources,etc.,and there were other sources with smaller contribution ratios such as restaurant sources and biomass combustion sources in urban and suburban stations respectively.Suburban station was much more influenced by secondary generation than urban station.The relationship between PM2.5 concentration and urban heat island intensity(UHII)showed that suburban areas were more strongly affected by the heat island effect than urban areas.Meanwhile,the suburban PM2.5 concentrations showed a negative response with UHII in all seasons.Moreover,the stronger the UHII,the stronger the horizontal diffusion ability of PM2.5 in suburban areas,and the more obvious the difference in the vertical diffusion ability of urban and suburban PM2.5.The results of backward airflow trajectory analysis showed that suburban areas were significantly more influenced by pollution air masses from southwest(central Anhui and central Jiangsu),east(Yellow Sea and East China Sea)and sinking air masses at high altitude than urban areas,and the transport of foreign pollution air masses were the main reason for higher PM2.5 concentrations in suburban areas than urban areas.
PM2.5Suburban differencesSource analysisUrban heat islandBackward airflow trajectoryYandu district
NETL
NSTL
万方数据
