岳阳市一次O_(3)污染过程VOCs的组成与来源

Study of VOCs during O_(3) Pollution Process in Yueyang City:Composition and Source Apportionment

文章在岳阳市一个国家空气质量监测站附近,采用罐采样方法采集一次O_(3)污染过程期间环境全空气样品,利用预浓缩-GC/FID/ECD/MSD技术分析106种VOCs,共检出77种VOCs,研究其组成与来源。结果表明:岳阳市秋季大气TVOCs体积分数为(44.91±15.52)×10^(-9),以烷烃(19.9%~53.0%)、含氧挥发性有机物(OVOCs)(15.7%~55.9%)为主,优势物种为C2~C5烷烯烃、OVOCs、苯系物及卤代烃。秋季VOCs丙烯等效浓度范围为60.46×10^(-9)~230.04×10^(-9);臭氧生成潜势范围为76.37~394.30μg/m^(3);反应活性较高的物种为异戊烷、间/对-二甲苯和甲苯及丙烯、乙烯,根据反应活性物种初步判断岳阳市VOCs主要来源为机动车尾气排放及本地石油化工企业排放。特征比值溯源发现秋季异戊烷/正戊烷体积浓度比值为2.6,受机动车排放源影响更大。甲苯和苯、邻二甲苯和苯及间/对-二甲苯和苯体积浓度比值平均值分别为0.05、0.01和0.07,主要来源于生物质、生质燃料、煤燃烧源。邻二甲苯和乙苯、间/对-二甲苯和乙苯体积比值均值分别为0.80和2.71,受溶剂排放影响较大。控制岳阳市秋季O_(3)污染应着力于交通排放、LPG燃烧排放源、生物质燃烧源、石油化工及溶剂挥发排放的治理。

Ambient VOCs (volatile organic compounds) were studied during a period of O_(3) pollution event that took place in autumn in Yueyang City.Field environmental monitoring was thus conducted with whole air samples collected using a stainless steel canister plus the integral sampling apparatus and then the mixing ratios of 106 ambient VOCs were analyzed by GC/FID/ECD/MSD coupled with a three-stage pre-concentration.In addition,composition and source of 77 VOCs were characterized and apportioned,and PEC (propylene-equivalent concentration) and OFP (ozone formation potential) were used to estimate the reactivity of ambient VOCs.Results of the study showed that the average concentration of atmospheric total VOCs(TVOCs) was (44.91±15.52)×10^(-9);alkanes and OVOCs (Oxygenated VOCs) were the main predominant VOCs compound,accounting for 19.9%~53.0%and 15.7%~55.9%respectively,and C2~C5 alkanes and alkenes,OVOCs,BTEX and halogenated hydrocarbon were the dominant species.Furthermore,the range of total PEC and OFP of the ambient VOCs were 60.46×10^(-9)~230.04×10^(-9)and 76.37~394.30μg/m^(3) respectively.the key reactive species being isopentane,m/p-xylene,methylbenzene,propylene and ethylene,which indicated the main pollutant sources of VOCs were vehicle emission and the emission of the petrochemical factories in Yueyang;the volume concentration ratio of isopentane to n-pentane was 2.6,which was mostly attributed to vehicle emission;the volume concentration ratios of methylbenzene to benzene,ortho-xylene to benzene and m/p-xylene to benzene were 0.05,0.01 and 0.07 respectively,indicating the major pollutant sources were biomass,biomass burning and coal burning;and the volume concentration ratios of ortho-xylene to ethylbenzene and m/p-xylene to ethylbenzene were0.80 and 2.71,respectively,which revealed the major pollutants were solvents.Summarily,in order to control O_(3)pollution in Yueyang during autumn,the atmosphere pollution abatement should focuss on VOCs emissions of vehicles,LPG burning,biomass burning,and petrochemical factories,as well as the emission of solvents.