天津市西南部苯系物浓度季节及空间变化特征

采用预冷冻浓缩系统和气相色谱质谱联用仪,对天津市西南部BTEX(苯系物)浓度(以ρ计)进行了网格布点观测.结果表明:ρ(苯)、ρ(甲苯)、ρ(乙苯)、ρ(间对二甲苯)和ρ(邻二甲苯)的年均值分别为8.54、20.49、6.41、13.44和3.68μgm3,其中ρ(苯)和ρ(甲苯)均低于欧洲标准限值.各BTEX浓度季节变化明显,与当地大气稳定度、光化学反应以及即时气象条件等因素密切相关.利用各BTEX浓度的相关性,分析了不同类型采样点BTEX的来源,并证明工业企业和居民住宅附近存在非同源性苯和甲苯排放源.BT〔ρ(苯)与ρ(甲苯)之比〕年均值为0.49,接近我国机动车尾气排放特点,但BT值呈现出的季节变化特点可能与天津市供暖期燃煤排放有一定的关联.

Seasonal and Spatial Variations of BTEX in Southwest of Tianjin

BTEX concentrations in the air from southwest of Tianjin were monitored and analyzed by cryo-concentration and GC/MS.The results showed that the annual average concentrations of benzene,toluene,ethylbenzene,m,p-xylene and o-xylene were 8.54,20.49,6.41,13.44 and 3.68 μg/m3,respectively.The concentrations of benzene and toluene were lower than the European air quality standard values.BTEX compounds showed obvious seasonal variations which were closely related to area atmospheric stability,photochemical reaction and instant weather conditions.The pollutant sources for each type of points were analyzed by the correlation coefficients between BTEX,which proved that an emission source of non-homologous benzen and toluene was being nearby industrial enterprises and Residential buildings.The annual mean ratio of benzene to toluene(B/T) was 0.49,which is close to the characteristic value of domestic automobile exhaust in China,but there was also a certain correlation between seasonal variations of B/T values and fossil fuel combustion during the heating period in Tianjin.