黄河三角洲地区大气复合污染特征、成因与VOCs来源解析

Characteristics and Formation of Complex Air Pollution and Sources of VOCs in the Yellow River Delta Region

为了解黄河三角洲区域细颗粒物(PM_(2.5))和臭氧(O_(3))大气复合污染特征和成因,本文利用2021年和2022年夏秋季黄河三角洲中心城市东营市、滨州市的挥发性有机物(VOCs)连续观测数据及常规污染物数据,识别对O_(3)和二次有机气溶胶(SOA)生成有显著贡献的VOCs物种并对VOCs进行来源解析,同时利用基于观测的化学盒子模型探讨O_(3)的生成敏感性.结果表明:①黄河三角洲地区PM_(2.5)和O_(3)浓度“双高”的大气复合污染主要出现在秋季,夏季东营市和滨州市首要污染物均为O_(3),距离入海口越远的站点O_(3)超标天占比越高;秋季东营市和滨州市首要污染物均为PM_(2.5),且超标情况相近.②烯烃和含氧挥发性有机物(OVOCs)对臭氧生成潜势(OFP)的贡献大,优势物种为乙醛;芳香烃对SOA生成潜势(SOAFP)的贡献大,优势物种为1,2,3-三甲苯.③东营市夏秋季O_(3)生成均处于VOCs和NO_(x)协同控制区,且夏季O_(3)对NO_(x)更为敏感;滨州市夏秋季O_(3)生成分别处于VOCs和NO_(x)协同控制区、VOCs控制区,且夏季O_(3)对NO_(x)敏感性更高,秋季对VOCs敏感.④油气挥发源、工业排放源和机动车尾气排放源为该区域VOCs的主要来源,且VOCs来源解析结果存在空间上和季节上的差异.夏季,区域溶剂源和生物源VOCs的贡献率增加,东营市溶剂源贡献率(28.2%)明显高于滨州市(6%),机动车尾气排放源贡献率(11.5%)低于滨州市(29.6%);秋季,区域燃烧源和生物质燃烧源贡献率增加,东营市(25.9%)油气挥发源贡献率明显低于滨州市(42.4%).研究显示,黄河三角洲地区夏季应实施VOCs和NO_(x)的协同减排,秋季应优先控制VOCs排放;其次需要加强对油气挥发源、工业排放源和机动车尾气源VOCs的管控.

During the summer and autumn seasons of 2021 and 2022,volatile organic compounds(VOCs)and conventional pollutants were continuously monitored in the ambient air of Dongying City and Binzhou City in the Yellow River Delta to better understand the characteristics and causes of combined air pollution of fine particulate matter(PM_(2.5)) and ozone(O_(3)).The sources of VOCs were examined and VOCs species that contribute significantly to the production of secondary organic aerosols(SOA)and O_(3) were identified.The observed chemical box model was used to study the sensitivity of O_(3) formation.The results showed that:(1)In the Yellow River Delta region,the atmospheric composite pollution with‘double high’concentrations of PM_(2.5)and O_(3)mainly occurs in autumn.O_(3)was the main pollutant in summer.The greater the distance from the estuary,the higher the proportion of exceeding O_(3) days.The main pollutants in autumn are PM_(2.5)in Dongying City and Binzhou City,and the situation of exceeding the standard is similar.(2)Alkenes and volatile organic compounds(OVOCs)were the major contributing species to O_(3) generation potential(OFP),while acetaldehyde was the dominant species.Aromatics contributed the most to SOA generation potential(SOAFP)with 1,2,3-trimethyl benzene being the dominant species.(3)O_(3)formation in Dongying City is in the cooperative control area of VOCs and NO_(x) in summer and autumn,and O_(3) is more sensitive to NO_(x) in summer.In Binzhou City,O_(3) formation is in the cooperative control area of VOCs and NO_(x) in summer and in the control area of VOCs in autumn,and O_(3) is more sensitive to NO_(x) in summer and sensitive to VOCs in autumn.(4)The main sources of VOCs in the urban areas of the Yellow River Delta were petroleum and gas evaporation,industrial emissions,and vehicle exhaust emissions.Moreover,there are spatial and seasonal differences in VOCs source analysis results.During summer,there was an increase in the contribution rate of VOCs originating from regional solvent sources and biological sources.In Dongying City,the contribution rate of VOCs from solvent sources(28.2%)was significantly higher than that in Binzhou City(6%),while the contribution rate of vehicle exhaust emissions(11.5%)was lower than that in Binzhou City(29.6%).In autumn,the contribution rate of combustion sources and biomass burning sources increased in the region,and the contribution rate of oil and gas volatile sources in Dongying City(25.9%)is significantly lower than that in Binzhou City(42.4%).The results show that the coordinated emission reduction of VOCs and NO_(x)should be implemented in summer in the Yellow River Delta region,and the emission reduction of VOCs should be prioritized in autumn.Secondly,strengthen the emission control of oil and gas volatile sources,industrial emission sources and vehicle exhaust emission sources VOCs.