2008北京残奥会期间大气黑碳气溶胶污染特征

利用单颗粒黑碳光度计(SP2)对2008年残奥会期间北京市黑碳(BC)气溶胶的质量浓度、粒径分布及单颗粒混合态进行连续在线观测.结果表明:观测期间BC浓度均值为1.65μg/m3,低于往年同期水平;质量粒径分布呈单峰型,峰值位于207nm;内混态BC比例平均为56.1%,高于其他国内外城市,说明本地源排放贡献相对较小.随大气边界层高度及本地源排放变化,BC浓度在上午8:00和午夜0:00出现2个峰值,内混态BC比例日变化趋势与之相反.风向风速分析表明,残奥会期间来自五环外未限行区域的机动车排放对市区BC浓度有明显影响.

Black carbon measurement during Beijing Paralympic Games

The mass concentration, size distribution and mixing state of black carbon (BC) were characterized during Beijing Paralympics using a newly developed single-particle soot photometer (SP2). The measurement showed that the average BC mass concentration was 1.65μg/m3, which was lower than the same period of former years. The average mass size distribution had one mode peaking at a BC volume-equivalent diameter of 207nm. About 56.1% of the BC particles were internally mixed, higher than other cities, suggesting local emission was relatively less. With the variation of boundary layer height and local emissions, the BC concentrations exhibited a diurnal pattern of “two peaks” peaking at 8 a.m. and 0 a.m. While the diurnal pattern of internally mixed BC percentage exhibited an opposite manner. Wind direction analysis showed that BC in urban was effected significantly by traffic emission from vehicles outside the limit area during the Paralympic Games.