某典型石油化工园区冬季大气中VOCs污染特征

利用TH-300B挥发性有机物(volatile organic compounds,VOCs)在线监测系统于2014年12月~2015年2月对我国某石油化工园区的VOCs进行连续在线监测.分析了其组成特征、时间变化特征、来源以及光化学活性特征.结果表明,研究区冬季大气中VOCs的混合体积分数较高,烷烃占据主导地位,占TVOCs的86.73%;TVOCs、烷烃、烯烃、芳香烃的昼夜变化特征均表现为夜间高而白天低,且烷烃、烯烃的变化与TVOCs较为一致.利用主成分分析-多元线性回归(PCA-MLR)模型解析得到5个因子,分别表征燃料挥发源、工业排放源、汽油车尾气和植物排放混合源、柴油车尾气排放源和燃料燃烧源,其贡献率分别为60.02%、8.50%、2.07%、12.21%、17.20%.利用Propy-equiv法和MIR法计算得出该研究区冬季大气中各类VOCs对臭氧生成的相对贡献率的大小均表现为烷烃烯烃芳香烃,其中环戊烷、正丁烷和1-戊烯的贡献率较高,气团光化学年龄较长.

Characteristics of VOCs Pollution in the Winter Atmosphere of a Typical Petrochemical Industry Park

Concentrations of volatile organic compounds (VOCs) in ambient air of a typical petrochemical industry park were measured using an on-line monitor (TH-300B) from December 2014 to February 2015. The composition, temporal variations, sources, and photochemical reactivity of VOCs were analyzed. Alkanes were the most abundant VOC species and contributed to 86.73% to total VOC concentrations in winter. Concentrations of TVOCs, alkanes, alkenes, and aromatic hydrocarbons were high at night and low during the day. The changes in alkane and alkene concentrations were consistent with those in TVOC concentrations. Using principal component analysis and multiple linear regression (PCA-MLR) in combination, five sources of VOCs were identified; fuel evaporation, industrial emissions, a mix of gasoline vehicle exhaust and plant emissions, diesel vehicle exhaust emissions, and fuel combustion with contributions of 60.02%, 8.50%, 2.07%, 12.21%, and 17.20%, respectively. Propylene-equivalent concentration (Propy-Equiv) and maximum incremental reactivity (MIR) method were used to calculate the contributions of VOCs measured in the study area to ozone production. Alkanes contributed most to ozone production followed by alkenes and aromatic hydrocarbons. The contribution rate of cyclopentane, n-butane, and 1-pentene were higher owing to their long photochemical age in the study area.