天津滨海新区冬季环境空气中挥发性有机物的污染特征及溯源分析

Pollution Characteristics and Trace Analysis of Volatile Organic Compounds in Ambient Air of Tianjin Binhai New Area in Winter

采用热脱附–气相色谱质谱法,对天津科技大学滨海校区逸夫楼北侧冬季环境空气中的挥发性有机物(VOCs)进行分析.建立空气中挥发性有机物的分离及识别各类化合物的方法.研究不同空气质量指数(AQI)下挥发性有机物的变化规律.探讨空气中挥发性有机物的溯源方法及过程.结果表明:SH-Rxi-624Sil MS色谱柱对低沸点挥发性有机物、芳香烃和烷烃类的物质表现出良好的分离效果.空气质量为优时,羧酸和醛类物质是主要污染物,分别占比26.9%和18.5%.而当空气质量为良、轻度、中度和重度污染时,主要污染物是芳香烃和烷烃,依次占比34.1%和20.9%、32.9%和16.0%、38.6%和17.1%、40.9%和18.4%.随着AQI的增加,VOCs的物质种类、峰强度和峰面积也增加.通过特征比值法溯源分析,ρ_(甲苯)与ρ_(苯)的比值在1.0~2.4,芳香烃和烷烃主要是机动车尾气排放造成,而羧酸类和醛类物质可能来源于监测站位周围植物的天然排放.

In this study the volatile organic compounds(VOCs)in winter air in the north of Yifu Building,Binhai campus of Tianjin University of Science and Technology were analyzed by thermal desorption gas chromatography-mass spectrometry.A method for the separation and identification of volatile organic compounds in air was established.The variation of volatile organic compounds under different air quality index(AQI)was studied.The traceability method and process of volatile organic compounds in air were discussed.The results of the study showed that the SH-Rxi-624Si MS column demonstrated good separation effect for low boiling point volatile organic compounds,aromatic and alkane substances.When the air quality was excellent,carboxylic acids and aldehydes were the main pollutants,accounting for 26.9%and 18.5%,respectively.When the air quality was good,light,moderate and heavy pollution,the main pollutants were aromatic hydrocarbons and alkanes,accounting for 34.1%and 20.9%,32.9%and 16.0%,38.6%and 17.1%,40.9%and 18.4%,respectively.With the increase of AQI index,the substance type,peak intensity and peak area of VOCs were increasing.According to the traceabil ity analysis by characteristic ratio method,the ratio of toluene/benzene was between 1.0 and 2.4.Aromatic hydrocarbons and alkanes are mainly caused by vehicle exhaust emissions,while carboxylic acids and aldehydes may come from the natural emissions of plants around the monitoring point.