南充城区秋季VOCs污染特征及来源分析

Analysis on the Characteristics and Sources of Volatile Organic Compounds in Autumn in the Urban of Nanchong City

为了解南充城区秋季大气环境中挥发性有机物(VOCs)的污染特征及来源,2018年11月7日~11月15日,利用在线GC-MS对南充城区的VOCs成分进行了连续在线监测,并运用PMF模型对VOCs的来源进行了解析。结果表明:监测期间,南充城区的VOCs共检出103种,小时平均体积分数约为(32.5±5.7)×10-9,由烷烃、含氧挥发性有机物(OVOCs)、芳香烃、烯烃、卤代烃等组成,占比分别为38.5%、31.7%、10.2%、9.5%和8.0%;各类污染物中烯烃对总臭氧生成潜势(OFP)的贡献度最大,占32.6%,OVOCs次之(31.7%),其余依次为芳香烃(26.0%)、烷烃(8.3%)和卤代烃(1.1%);VOCs的日变化总体呈现两高两低的趋势,但变化幅度较小,VOCs与NO 2、CO、PM 2.5和PM 10浓度呈正相关关系,与O 3的浓度呈负相关关系;运用PMF模型共解析出道路交通源、工业源、油气挥发、燃料燃烧和餐饮油烟5个因子,道路交通源是南充城区秋季大气环境VOCs最大贡献源(29.3%),其次为工业源(26.1%)和油气挥发(23.0%),燃料燃烧(14.4%)和餐饮油烟(7.2%)的贡献最小。相关分析表明:南充城区秋季大气环境中的VOCs受机动车尾气、工业溶剂、油气挥发和生物质燃烧的影响较大,建议后期应重点关注这4类污染源。

In order to understand the characteristics and sources of volatile organic compounds(VOCs)in the urban of Nanchong during the autumn,the components of VOCs were monitored continuously using online GC-MS from November 7th to November 15th,2018.The sources of VOCs were analyzed using Positive matrix factorization(PMF)model.The results showed that during the monitoring period,a total of 103 kinds of VOCs were detected in Nanchong urban area,with an average hourly volume fraction of(32.5±5.7)×10-9,consisting of alkanes(38.5%),OVOCs(31.7%),aromatics(10.2%),alkenes(9.5%),and halocarbons(8.0%).Alkenes(32.6%)contributed most to the total ozone formation potential(OFP)in various pollutants,followed by OVOCs(31.7%),aromatics(26.0%),alkanes(8.3%)and halocarbons(1.1%).The diurnal variation of VOCs during the autumn generally showed a trend of two highs and two lows,but the variation of range was small.VOCs were positively correlated with NO 2,CO,PM 2.5 and PM 10,and negatively correlated with O 3.PMF model was adopted and identified five factors,including motor vehicles exhaust(29.3%),industry solvents(26.1%),oil and gas volatilization(23.0%),coal and biomass burning(14.4%)and cooking fumes(7.2%).The correlation analyses showed that the VOCs were mainly affected by motor vehicle exhaust,industrial solvent,oil and gas volatilization and biomass burning.In the future,it is suggested that we should focus on and take strict measures on these four types of pollution sources.