2015～2018年中国代表性城市PM2.5浓度的城乡差异

Urban-rural differences in PM2.5 concentrations in the representative cities of China during 2015～2018

选取中国6大城市群中的11座代表性城市为研究区域,将监测站点划分为城区、郊区和乡村站,进而分析各城市间PM2.5浓度的城乡差异规律.结果表明,同一城市群各城市之间,或同一城市的城区、郊区、乡村站间PM2.5日变化皆较为相似.京津冀和长三角地区的城市城区PM2.5浓度最高,高于郊区7.8%~9.7%,高于乡村11.3%~16.9%,而粤港澳大湾区和内陆城市群(成渝、长江中游、关中平原城市群)的城市郊区PM2.5浓度最高,高于城区2.6%~11.2%,高于乡村16.7%~26.5%.各城市间城乡PM2.5浓度差值的日变化规律不尽相同,可呈单峰(如上海)或双峰(如杭州)变化,极值可出现在白天(如广州),亦可在夜间(如深圳).PM2.5的排放与传输扩散共同对11城市城乡PM2.5浓度分布产生影响.

Observation sites in the 11 representative cities from 6 main city clusters in China were selected in this study.These observation sites were categorized into urban,suburban and rural to investigate urban-rural differences in PM2.5 concentrations.Results showed that the diurnal variation patterns of PM2.5 were relatively similar in the cities from the same city cluster,and they were also similar among the urban,suburban and rural areas in a specific city.In Jingjinji Megalopolis and Yangtze River Delta Megalopolis,the PM2.5 concentrations from the urban sites were the highest,7.8%~9.7%higher than those from the suburban sites and 11.3%~16.9%higher than those from the rural sites.However,in Guangdong-Hong Kong-Macao Greater Bay Area and the inland city clusters(i.e.,Chengyu Megalopolis,Middle Yangtze River Valley Megalopolis and Guanzhong Plain Megalopolis),the PM2.5 concentrations from the suburban sites were the highest,2.6%~11.2%higher than those from the urban sites and 16.7%~26.5%higher than those from the rural sites.Moreover,different diurnal variation patterns of urban-rural PM2.5 concentration differences were observed in different cities.For example,the diurnal variation of urban-rural PM2.5 concentration difference was unimodal in Shanghai but bimodal in Hangzhou.The maximum of urban-rural PM2.5 concentration difference occurred during the daytime in Guangzhou but during the nighttime in Shenzhen.Further,the PM2.5 concentration distribution in the urban,suburban and rural areas of the 11representative cities were under the combined effects of PM2.5 emission,transportation and diffusion.