南京市大气VOCs污染特征及其臭氧生成潜势分析

基于2016—2022年南京市大气挥发性有机物（VOCs）自动监测数据，分析VOCs污染特征及其臭氧生成潜势（OFP）。结果表明：2016—2022年南京市大气VOCs及其组分体积分数均显著下降，TVOCs 7年均值为21.7×10-9，各组分占比从大到小依次为烷烃＞烯烃＞芳香烃＞炔烃；TVOCs及烷烃、烯烃、芳香烃季节变化一致，均为冬季＞秋季＞春季＞夏季，炔烃为冬季＞春季＞秋季＞夏季；TVOCs及烷烃、烯烃、炔烃月变化整体呈“V”字型特征，芳香烃近似为“W”型；除炔烃外，小时体积分数日变化基本呈“单峰型”特征。2016—2022年OFP年际变化呈显著下降趋势，7年均值为132.1 μg/m3；OFP贡献较大的组分为烯烃（39.1%）和芳香烃（38.1%），臭氧生成的VOCs关键物种为乙烯、间/对二甲苯、甲苯、丙烯和异戊二烯，控制烯烃和芳香烃排放有利于南京市的臭氧污染防治。

Analysis of Pollution Characteristics of Atmospheric VOCs and Their Ozone Formation Potential in Nanjing

Based on the automatic monitoring data of atmospheric volatile organic compounds（VOCs）in Nanjing from 2016 to 2022， this study analyzed the pollution characteristics of VOCs and their ozone formation potential（OFP）. The results showed that the volume fraction of atmospheric VOCs and their components in Nanjing decreased significantly from 2016 to 2022， the average value of TVOCs in 7 years was 21.7×10-9. The proportion of each component in order from large to small was alkanes， alkenes， aromatics and alkynes. The concentrations of TVOCs， alkanes， alkenes and aromatics had the same seasonal variations， with winter＞autumn＞spring＞summer. For alkyens， it was winter＞spring＞autumn＞summer. The overall monthly variation of TVOCs， alkanes， alkenes and alkynes showed a “V” character， and aromatics was approximately a “W” type. Except for alkynes， the diurnal variation of hourly volume fraction was basically “unimodal”. The interannual variation of OFP showed a significant downward trend from 2016 to 2022， with a 7-year mean of 132.1 μg/m3. The components that contributed more to OFP were alkenes（39.1%）and aromatics（38.1%）. The key species of VOCs generating ozone were ethylene， m/p-xylene， toluene， propylene and isoprene. Reducing the emission of alkenes and aromatics was beneficial to ozone prevention and control in Nanjing.