典型中部地区南阳市VOCs污染特征及对O3生成影响

VOCs Pollution Characterization and Its Influence on O3 Pollution in a Typical Central China City Nanyang

  • 摘要: 为研究我国中部地区臭氧(O3)污染成因和挥发性有机物(VOCs)污染特征及来源,于2022年对河南省南阳市的VOCs进行了为期一年的在线观测,并探究了其对O3生成的影响. 南阳市占地面积大、人口多,是我国中部地区典型代表城市,本研究将2022年南阳市环境空气中O3月均浓度较高的月份(5—9月)定义为O3污染频发月,其余月份定义为非O3污染频发月,研究了南阳市O3污染成因及VOCs污染特征和来源. 结果表明:①南阳市非O3污染频发月TVOCs (总挥发性有机物)体积分数为32.1×10−9±13.2×10−9,比O3污染频发月(19.4×10−9±5.9×10−9)高65.5%. 但O3污染频发月的OVOCs (含氧挥发性有机物)的体积分数比非O3污染频发月增加了5.3%,表明二次生成可能是南阳市O3污染频发月中OVOCs一个重要来源. ②臭氧生成潜势(OFP)计算结果表明,在2个研究阶段中,OVOCs的OFP贡献率超过50%,甲醛(35%)、乙醛(10%)、乙烯(9%)、间/对-二甲苯(5%)、甲苯(3%)是南阳市2个研究阶段中共有的影响O3生成的关键VOCs物种. ③经验动力学模型(EKMA)及相对增量反应活性(RIR)结果表明,在O3污染频发月,南阳市O3生成处于协同控制区,O3生成对人为源VOCs (特别是烯烃和芳香烃)和NOx更敏感. ④南阳市O3污染频发月VOCs的正定矩阵因子分解模型(PMF)结果显示,汽油车排放源(占29%)、溶剂使用源(占23%)、工业过程排放源(占21%)、居民生活排放源(占11%)、柴油车排放源(占10%)与植物源(占6%)是大气中VOCs的主要来源. 研究显示,南阳市在O3污染频发月期间二次生成是OVOCs的重要来源,且汽油车排放源是南阳市空气中VOCs的重要来源.

     

    Abstract: In order to study the ozone (O3) pollution and the characteristics and sources of volatile organic pollutants (VOCs) pollution in central China, this study conducted online observations of VOCs in 2022 and investigated their impact on the formation of O3 in Nanyang City, Henan Province. In order to guide more effective ozone and VOCs control in central China, this study conducted a one-year online VOCs monitoring in Nanyang City, a typical city in Central China, in 2022. The period from May to September was defined as the ozone pollution period, and the other months as non-ozone pollution period. The results showed that: (1) The average TVOCs concentration in non-ozone pollution months (32.1×10−9±13.2×10−9) was 65.5% higher than that in ozone pollution months (19.4×10−9±5.9×10−9). However, the concentration of OVOCs in ozone pollution months was 5.3% higher than that in the non-ozone pollution months, indicating that secondary formation may be a significant source of OVOCs in ozone pollution months in Nanyang City. (2) During both observation periods, the OFP of OVOCs accounts for more than 50%, among which formaldehyde (35%), acetaldehyde (10%) and ethylene (9%), m-p-xylene (5%) and toluene (3%) were the most important OFP contributing species. (3) Empirical kinetic model approach (EKMA) and relative incremental reactivity (RIR) calculation revealed that the O3 formation sensitivity was in transitional regime during the ozone pollution months, and O3 production was sensitive to both anthropogenic VOCs (particularly alkene and aromatic hydrocarbons) and NOx. (4) Positive matrix factorization (PMF) analysis identified six sources during the ozone pollution months: gasoline vehicles (29%), solvent use (23%), industrial process emissions (21%), residential emissions (11%), diesel vehicle emissions (10%) and plant emissions (6%). The research shows that during the ozone pollution months, secondary generation was a significant source of OVOCs, while gasoline vehicle emissions were an important contributor to atmospheric VOCs in Nanyang City.

     

/

返回文章
返回