Spatial distribution and interannual variation of surface PM10 concentrations over eighty-six Chinese cities

The spatial distribution of the aerosols over 86 Chinese cities was reconstructed from air pollution index (API) records for summer 2000 to winter 2006. PM10 ( particulate matter <= 10 mu m) mass concentrations were calculated for days when PM10 was the principal pollutant, these accounted for 91.6% of the total 150 428 recorded days. The 83 cities in mid-eastern China (100 degrees E to 130 degrees E) were separated into three latitudinal zones using natural landscape features as boundaries. Areas with high PM10 level in northern China (127 to 192 mu g m(-3)) included Urumchi, Lanzhou-Xining, Weinan-Xi'an, Taiyuan-Datong-Yangquan-Changzhi, Pingdingshan-Kaifeng, Beijing-Tianjin-Shijiazhuang, Jinan, and Shenyang-Anshan-Fushun; in the middle zone, high PM10 (119-147 mu g m(-3)) occurred at Chongqing-Chengdu-Luzhou, Changsha-Wuhan, and Nanjing-Hangzhou; in the southern zone, only four cities (Qujing, Guiyang, Guangzhou and Shaoguan) showed PM10 concentration > 80 mu g m(-3). The median PM10 concentration decreased from 108 mu g m(-3) for the northern cities to 95 mu g m(-3) and 55 mu g m(-3) for the middle and southern zones, respectively. PM10 concentration and the APIs both exhibited wintertime maxima, summertime minima, and the second highest values in spring. PM10 showed evidence for a decreasing trend for the northern cities while in the other zones urban PM10 levels fluctuated, but showed no obvious change over time. The spatial distribution of PM10 was compared with the emissions, and the relationship between the surface PM10 concentration and the aerosol optical depth (AOD) was also discussed.