Effect Of Virescence On Inhalable Particulate Matter (PM10) And Dustfalls In Downtown Of Beijing

This work was performed for 2 years from January 2001 to January 2003. It was aimed to investigate the effects of virescence overlay rates and greenbelt types on inhalable particulate matter with aerodynamic diameters < l0μm, PM10 and dustfall in Beijing downtown. For sampling of PM10 7 areas were chosen, which were Fangzhuang Area, Tiantan Park, Dongsi Area, Agricultural Exhibition Hall in China, National Olympic Center of China, Party School of CPC Beijing Municipal Committee, and Tsinghua University Area, and several typical greenbelt types were chosen in each area. Dustfalls were measured in different greenbelt types in Beijing Landscape Scientific Institute and in China Agricultural University respectively. The results observed were as bellow.1) Annual averages of PM10 were different significantly in different areas sampled above, and the minimum was in Agricultural Exhibition Hall, but the maximum was in Dongsi Area. The annual averages of PM10 in different areas were related to their virescence overlay rates, which were calculated based on the picture of satellite remote sensing, and a tendency of decreasing was obtained in the annual average with increasing of virescence overlay rate.2) Significant difference was obtained in seasonal averages of PM10 when compared the different areas. The difference was depended on different seasons, and a decreasing tendency in PM10 was with the bigger areas determined.3) Annual averages of PM10 were lower in compound plantation structures (arbor-shrub type, shrub-herb type, arbor-shrub-herb type, and arbor-herb type) than in single ones (lawn type, arbor type, and shrub type), however, it was lower obviously in all the sites covered with various greenbelt types when compared with road.4) The difference of PM10 in different greenbelt types was gained in spring and autumn mainly. The value of PM10 was lower in compound plantation structure than in single structure.5) Annual averages of PM10 were depended on areas of greenbelts. Effect of decreasing PM10 could be observed when the greenbelts reached certain areas in lawn type, - arbor-shrub type, shrub-herb type, arbor-shrub-herb type and shrub type, but not in arbor-herb type and arbor type.6) Effect of greenbelt areas on the seasonal averages of PM10 was much complicated, and the effect was obtained in autumn only and certain areas were required for all kinds of greenbelts.7) Dustfalls was least in summer, but was most in spring. Of 5 greenbelt types, Lawn type had the lowest value of dustfalls, but the ground without plant covering was just opposite. This indicated that lawn probably had the effect of suppressing dust.The results above indicated that PM10 concentration could be decreased in a certain extend, and the quality of air in downtown of Beijing could be improved by increase of virescence overlay rate and making suitable greenbelt types.