三峡库区开州城区大气VOCs污染的季节特征及来源解析

Seasonal Characteristics and Source Analysis of Air VOCs Pollution in Kaizhou Urban Area of the Three Gorges Reservoir Area

为深入了解重庆市开州区中心城区挥发性有机物(VOCs)对臭氧(O_(3))和二次有机气溶胶(SOA)污染的影响,基于长时间序列在线监测数据统计分析了57种臭氧前体混合物(PAMS)的VOCs污染特征,并利用最大增量反应活性法估算了VOCs对臭氧生成潜势(OFP)。结果表明,开州区大气中VOCs浓度变化为冬季(20.18μg/L)>秋季(19.89μg/L)>春季(19.81μg/L)>夏季(14.58μg/L),烷烃、烯烃和芳香烃排放贡献占比分别为43.2%、37.8%和19.0%;烯烃的OFP占比最大(51.4%),其次为芳香烃(38.3%)和烷烃(10.3%);芳香烃对SOA生成的贡献高达90.5%;区域VOCs气团较为新鲜且受到近距离传输,主要受机动车尾气和燃煤/生物质燃烧、燃油蒸发影响;移动源和溶剂使用源的有效控制是降低区域VOCs光化学反应生成O_(3)和SOA污染的关键。

In order to deeply understand the influence of volatile organic compounds(VOCs)on ozone(O_(3))and secondary organic aerosol(SOA)pollution in the central urban area of Kaizhou district,Chongqing,the VOCs pollution characteristics of 57 ozone precursors(PAMS)were analyzed based on long-term online monitoring data,and the maximum incremental reactivity method was used to estimate the potential of VOCs for ozone formation potential(OFP).The results showed that the atmospheric VOCs concentration in Kaizhou region changed as follows:winter(20.18μg/L)>autumn(19.89μg/L)>spring(19.81μg/L)>summer(14.58μg/L),and the contribution of alkane,olefin and aromatic hydrocarbon were 43.2%,37.8%and 19.0%,respectively OFP ratio of olefin was the largest(51.4%),followed by aromatic hydrocarbon(38.3%)and alkanes(10.3%).The contribution of aromatic hydrocarbons to SOA generation is up to 90.5%;The regional VOCs air mass is relatively fresh and transmitted at short distance,which is mainly affected by motor vehicle exhaust,coal/biomass combustion and fuel evaporation.Effective control of mobile source and solvent use source is the key to reduce O_(3) and SOA pollution from regional VOCs photochemical reactions.