冬季大气中苯系物污染特征及人体暴露水平分析

2007年冬季对乌鲁木齐市空气中苯系物(BTX)进行了网格布点监测,并用气相色谱仪进行样品分析. 结果表明:冬季大气中苯(B)、甲苯(T)和二甲苯(X)的质量浓度分别为5.62~20.57,3.40~122.82和2.20~129.15 μg/m3. 与欧洲标准相比,该地区ρ(苯)较高,且部分地区高于欧洲控制标准;而ρ(甲苯)和ρ(二甲苯)较低,达到欧洲目标限值水平. 苯系物质量浓度和空间分布特点较显著,ρ(甲苯)与ρ(二甲苯)的空间分布较为一致,但与ρ(苯)的分布特点不同. 最后通过对苯系物的人口加权大气污染暴露水平进行分析可知,乌鲁木齐市ρ(苯),ρ(甲苯)和ρ(二甲苯)的污染暴露水平在空间分布上较为均匀,但人口密度空间分布不均匀,故与ρ(苯)分布没有显著的相关性. 城区的ρ(苯),ρ(甲苯)和ρ(二甲苯)的人口加权平均值均略低于全市人口加权平均值,说明虽然城区人口密度较高,但其ρ(苯),ρ(甲苯)和ρ(二甲苯)的人口加权污染暴露水平相对较低. 

Analysis of Characteristics and Human Exposure of BTX Pollution in Ambient Air in Winter

Air samples collected from Urumuqi City by grids in winter 2007 were analyzed by GC to understand BTX concentration in air. The results showed that the mass concentrations of benzene, tolzene and xylene were 5.62-20.57, 3.40-122.82 and 2.20-129.15 μg/m3, respectively. Compared to European air standards, benzene mass concentration was high in Urumuqi City, but tolzene and xylene mass concentrations met the European air standard. Tolzene and xylene mass concentrations showed similar spatial distributions, but benzene differed. According to the analysis of population-weighted exposure level (PWEL) of the BTX, the exposure levels of benzene, toluene and xylene were evenly distributed in space; however, the population density was unevenly distributed, so the results showed no correlation. In the center area, the population-weighted exposure concentration of the BTXwas a little lower than that in the whole city area, which indicated that though population density was high in the center, the PWEL of the BTX was lower.