Quantitative relationship between visibility and mass concentration of PM2.5 in Beijing.
The pollution of particulate matter less than 2.5 microm (PM2.5) is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U.S. national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composition of PM2.5 varied largely with season, but was similar at different monitor stations in the same season. The fine particles (PM2.5) cause atmospheric visibility deterioration through light extinction. The mass concentrations of PM2.5 were anti-correlated to the visibility, the best fits between atmospheric visibility and the mass concentrations of PM2.5 were somehow different: power in spring, exponential in summer, logarithmic in autumn, power or exponential in winter. As in each season the meteorological parameters such as air temperature and relative humidity change from day to day, probably the reason of above correlations between PM2.5 and visibility obtained at different seasons come from the differences in chemical compositions of PM2.5.
Wang
Jing-Li
JL
Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China. wjingli123@163.com
Zhang
Yuan-Hang
YH
Shao
Min
M
Liu
Xu-Lin
XL
Zeng
Li-Min
LM
Cheng
Cong-Lan
CL
Xu
Xiao-Feng
XF
D000397:Air Pollution / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D006813:Humidity; D010316:Particle Size; D012621:Seasons; D013696:Temperature