重庆市代表性城区苯系物污染特征研究

Pollution Level and Variation of BTEX in a Representative District of Chongqing

为全面了解环境空气中苯系物污染状况和时空分布特征,以一代表性城区为观测对象,以定点观测与功能区观测相结合的方式在冬夏季节开展苯系物观测。观测结果表明:研究区域环境空气中苯系物浓度水平已不容乐观,需要得到有效的控制。组成上,甲苯>二甲苯>苯>乙苯>苯乙烯>异丙苯。空间分布上,工业区、混合区苯系物浓度相对较大,投诉集中区域呈现甲苯异常高值;垂直分布上,甲苯、乙苯、二甲苯浓度变化趋势一致,相对高值出现在21 m和81 m;苯的变化略有差异,在45 m出现明显高值。时间分布上,苯、乙苯、二甲苯冬季浓度大于夏季,而甲苯,道路区冬季和夏季浓度相差不大;日变化特征中,苯系物的变化具有多峰型特征,早晚浓度较高,中下午浓度较低。

To fully understand the pollution level and variation of BTEX in ambient air, BTEX in ambient air at representative sites in a representative district of Chongqing were observed. Result showed that concentration of BTEX in the regional ambient air need to be paid more attention and to be effectively controlled. In ambient air,the concentration of BTEX was ranked as toluene 〉xylene 〉benzene 〉ethylbenzene 〉styrene 〉cumene. BTEX concentration in industrial zone and mixing zone was larger. The concentrated area of complaints showed abnormally high values of toluene,so the contribution of industrial sources needed to be paid more attention. As for vertical distribution,toluene,ethylbenzene,xylene showed the same trend that higher value appeared in 21 meters and 81 meters while the higher concentration of benzene existed in 45 meters. The concentrations of benzene,ethylbenzene and xylene in winter were higher than those in summer while toluene concentration in the road area in winter and summer were not so different. For daily variation,the concentrations of BTEX were higher in morning and night while lower at noon and afternoon.