沈阳市不同功能区挥发性有机物分布特征及臭氧生成潜势

Pollution Characteristics and Ozone Formation Potential of Ambient VOCs in Different Functional Zones of Shenyang,China

采用德国AMA-GC 5000在线气相色谱仪对沈阳市的工业区、交通区和文教混合区这3个不同功能区进行大气挥发性有机物(VOCs)观测,分析沈阳市不同功能区大气VOCs的分布特征,并利用最大增量反应活性(MIR)估算了大气VOCs的臭氧生成潜势(OFP).结果表明,沈阳市大气VOCs平均总浓度为(82.19±54.99)μg·m^(-3),其中,采暖期浓度高于非采暖期,且工业区浓度较交通区和文教混合区明显偏高.VOCs浓度日变化曲线中,受早晚交通高峰影响为主的交通区和文教混合区呈双峰特征,工业区受工厂不定时运作排放影响存在多峰.交通区和文教混合区VOCs组分占比表现为:烷烃>芳香烃>烯烃>炔烃,但工业区炔烃占比高于烯烃,由B/T和E/A比值反映交通区和文教混合区受机动车尾气排放和燃料燃烧共同影响,工业区还受石油化工影响产生新鲜气团较多,且采暖期较非采暖期老化气团多.沈阳市大气VOCs的OFP贡献均值为232.89μg·m^(-3),烯烃组分对各功能区贡献均占第一,且工业区的芳香烃组分因浓度高贡献也较大.

Ambient volatile organic compounds(VOCs)were determined by GC 5000 online gas chromatography in three functional areas of Shenyang,namely industrial,traffic,and mixed cultural and educational areas.The pollution characteristics of VOCs in these functional areas during the heating and non-heating periods were analyzed,and the ozone formation potential(OFP)was estimated by using maximum incremental reactivity(MIR).The results show that the average mass concentration of VOCs is(82.19±54.99)μg·m^(-3)in Shenyang,of which the concentration in industrial areas is significantly higher than that in traffic and cultural and educational mixed areas,and the heating period is higher.The traffic and mixed cultural and educational areas have bi-modal characteristics due to the morning and evening traffic,and the industrial area has multiple peaks affected by the irregular operation hours.The proportion of VOCs in traffic and mixed cultural and educational areas shows the order of alkanes>aromatic hydrocarbons>alkenes>alkynes,but the proportion of alkynes in industrial areas is higher than that of alkenes.The benzene to toluene(B/T)and ethane to acetylene(E/A)ratios reflects that traffic and mixed cultural and educational areas were affected by both vehicle exhaust emissions and fuel combustion.The industrial zone is therefore affected by complex sources,and there are more aged air masses during the heating period than non-heating period.The average OFP contribution of atmospheric VOCs in Shenyang is 232.89μg·m^(-3).The contribution of alkenes is largest for all functional areas,and the aromatic component also contributes more due to the high concentration of industrial areas.