Wang Jing-Li, Zhang Yuan-Hang, Shao Min, Liu Xu-Lin, Zeng Li-Min, Cheng Cong-Lan, Xu Xiao-Feng
Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China.
J Environ Sci (China). 2006;18(3):475-81.
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.
小于2.5微米的颗粒物（PM2.5）污染是北京严重的环境问题。根据2001年季节性监测结果，PM2.5的年平均浓度超过了美国环境保护局（EPA）提出的美国国家环境空气质量标准的6倍多。PM2.5质量的主要贡献物是有机物、地壳元素和硫酸盐。PM2.5的化学成分随季节变化很大，但在同一季节的不同监测站则相似。细颗粒物（PM2.5）通过消光导致大气能见度下降。PM2.5的质量浓度与能见度呈反相关，大气能见度与PM2.5质量浓度之间的最佳拟合在某种程度上有所不同：春季为幂函数关系，夏季为指数函数关系，秋季为对数函数关系，冬季为幂函数或指数函数关系。由于在每个季节中，气温和相对湿度等气象参数每天都在变化，不同季节PM2.5与能见度之间上述相关性的原因可能来自PM2.5化学成分的差异。
