北京市大气细粒子的质量浓度特征研究

THE RESEARCH ON THE MASS CONCENTRATION CHARACTERISTICS OffINE PARTICLES IN BEIJING

中文关键词:  气象条件  定量关系  细粒子

英文关键词:Meteorological conditions  Quantificational relation  Fine particles(PM 2.5)

中文摘要:

      大气能见度的降低是当今国际上比较突出的城市环境问题。北京近年的监测结果表明,大气中通过消光作用使大气能见度下降的气溶胶细粒子的污染程度呈现上升趋势。从2001年对北京市气溶胶细粒子(空气动力学直径小于2.5μm的粒子)4个季节的采样监测结果分析(有效采样天数为50d)得出,北京市细粒子质量浓度年平均值已超过美国国家标准的7倍以上。研究发现细粒子的质量浓度不仅与环境条件有关,而且与气象条件也有着密切的关系。文中以细粒子的观测数据为基础,结合当时的气象条件进行细粒子浓度与气象条件定量关系的研究。

英文摘要:

      The decrease of visibility in at mosphere is the prominent problem of urban environment in the world.The recentyear's monitoring results in Beijing indicate that the pollution level of fine particles shows an increasing trend,which is a major factor to be responsible for visibility decreasing through the extinction.From the analysis of Beijing four season's samples of fine particles obtained in 2001,the mass concentration of fine particles in Beijing went beyond the USEPA standard badly and the annual average value was 6 times higher than the Standard.The relationship bet ween concentration of fine particles and weather conditions were analyzed qualitatively and quantitatively,based on the simultaneous observational data of fine particles and the weather conditions in this research.It was found that the mass concentration of fine particles was relevant notonly to the environmental condition but also to the meteorological conditions closely.There was a significant negative-correlation between mass concentration on fine particle and wind speed in Beijing with correlation coefficient -0.89 in winter breeze day and -0.60 in spring breeze day.Relative humidity was a key factor to influence mass concentration of fine particles.Mass concentration of fine particles was showed to be highly positive correlated with relative humidity,which correlation coefficient was near 1.0 in summer,0.99 in spring breeze day,and 0.81 in fog day in fall.Precipitation had great washout effecton mass concentration of fine particles.After heavy rainfal in summer,the mass concentration of fine particles decreased quickly.The concentration of fine particles was much lower than that in drizzle day.The results also showed that drizzle had some washout effects to remove fine particles.The synoptic regime had relatively great in fluence upon the mass concentration of fine particles.Before the synoptic regime coming,the fine particles pollution was seriously.When the regime passed,the PM 2.5 mass concentration decreased quickly and dramatically under north wind covering.