大连市夏季大气挥发性有机物污染特征及来源解析

Pollution Characteristic and Source Analysis of Volatile Organic Compounds in Summer in Dalian

为研究大连市挥发性有机物(VOCs)的浓度水平、组成特征和潜在来源,利用EXPEC 2000型大气挥发性有机物监测系统分别对大连市工业区和居民区2个点位2021年夏季大气中115种VOCs进行在线观测,分析了2个点位总挥发性有机物(TVOCs)体积分数、物种组成情况,估算了臭氧生成潜势(OFP),最后基于正定矩阵因子模型(PMF)依次探讨其来源。结果表明:观测期间工业区和居民区VOCs体积分数平均值分别为17.99×10^(-9)、18.17×10^(-9)。OFP均值分别为109.14、99.27μg/m^(3),在06:00—08:00和17:00—19:00上升趋势明显,可能与机动车早晚高峰有关,其中工业区OFP在21:00至次日03:00有突高现象。前者OFP贡献率排名前10物种包含间/对二甲苯、异戊二烯、乙醛等,后者包含异戊二烯、乙烯、丙烯等。PMF结果显示,化石燃料挥发源(32.8%)、溶剂使用源(31.4%)、化石燃料燃烧源(19.3%)和石油化工源(16.6%)是工业区点位VOCs主要来源,居民区点位是机动车源(40.2%)、化石燃料挥发源(32.6%)、溶剂使用源(20.2%)和植物源(7.0%)。前者溶剂使用源(57.4%)、化石燃料挥发源(19.8%)和化石燃料燃烧源(16.1%)对OFP贡献率较高,后者为机动车源(40.8%)、化石燃料挥发源(27.8%)和溶剂使用源(23.9%)。大连市工业区点位O_(3)污染控制可重点围绕工业生产过程中溶剂挥发、燃料逸散与燃烧展开,而居民区控制机动车尾气排放和油气挥发是关键。

In order to explore the concentration levels,composition characteristics and potential sources of VOCs(volatile organic compounds)in Dalian,EXPEC 2000 atmospheric VOC monitoring system had been used to conduct online observations of 115 VOCs in the atmosphere at two sites in industrial area and residential area in summer 2021.The volume fractions of total volatile organic compounds(TVOCs)and species composition were analyzed and OFP(ozone formation potential)was estimated at the two sites.The sources were analyzed sequentially based on PMF(positive definite matrix factorization)model.The results showed that the mean values of VOCs volume fraction in industrial and residential areas during the observation period were 17.99×10^(-9)and 18.17×10^(-9),respectively.The mean OFP values were 109.14μg/m^(3)and 99.27μg/m^(3),respectively,with a significant increasing trend in the early morning from 06:00-08:00 and in the evening from 17:00-19:00,which may be related to the morning and evening peaks of motor vehicles.Industrial area OFP had a sudden high at night from 21:00-03:00.The top 10 species contributing to OFP in industrial area were m/p-xylene,isoprene,acetaldehyde,etc.and in residential area were isoprene,ethylene,propylene,etc.The PMF results showed that fossil fuel volatilization(32.8%),solvent use(31.4%),fossil fuel combustion(19.3%),and petrochemical emissions(16.6%)were the main sources of VOCs for the industrial area sites,and motor vehicle emissions(40.2%),fossil fuel volatilization(32.6%),solvent use(20.2%),and plant emissions(7.0%)for the residential area sites.Sources of solvent use(57.4%),fossil fuel volatilization(19.8%),and fossil fuel combustion(16.1%)contributed more to OFP in industrial area,and motor vehicle emissions(40.8%),fossil fuel volatilization(27.8%),and solvent use(23.9%)in residential area.The control of O_(3)pollution in industrial areas of Dalian can focus on solvent volatilization,fuel fugitive and combustion in the industrial production process,while the control of motor vehicle emissions and oil vaporization in residential areas is the key.