| 疫情管控期西安PM2.5和O3污染特征及成因分析 |
| 摘要点击 1453 全文点击 121 投稿时间：2023-04-23 修订日期：2023-06-27 |
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| 中文关键词 PM2.5 臭氧（O3） PMF源解析 臭氧生成潜势（OFP） 聚类分析 |
| 英文关键词 PM2.5 O3 PMF source apportionment ozone formation potential （OFP） cluster analysis |
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| 中文摘要 |
| 基于西安疫情管控期空气监测数据,分析PM2.5和O3的时空序列特征,从PM2.5源解析、O3前体物VOCs溯源、气象要素和区域传输方向探讨污染成因.结果表明：①管控期PM2.5和O3分别同比上升20.39%和23.72%,其他参数均下降；与管控前后时期相比,管控期PM2.5和PM10日均值协同变化趋势减弱,O3和NO2此消彼长趋势增强；相比去年同期,PM2.5小时值升高11~19 μg·m-3,O3小时值夜间18：00~23：00升幅增大,为10~19 μg·m-3.②污染物浓度变化呈现一定的空间聚集协同性；受地形及植被阻滞吸附影响,PM2.5污染集中在北部,由于城郊NO2滴定效果弱于城区,表现为南部郊区O3污染较为严重.③管控期移动源对PM2.5贡献降低,化石燃料燃烧源和工艺过程源贡献升高；为防控疫情大量喷洒强氧化性的消杀剂使得含氧VOCs的体积分数升高,占比86.02%,O3前体物VOCs中乙醛、丙醛和丁烯醛是优先管控物种；气象要素对于污染物浓度的影响并非简单线性关系,在RH<P75区间,PM2.5浓度平均值随RH增大而升高,在T>P25区间,O3浓度平均值随T升高而升高；聚类分析表明与其他时期相比,管控期本地贡献率较高,为32.80%,由于管控期O3激增促进PM2.5的二次生成,区域重污染传输增强了PM2.5的不降反升情况. |
| 英文摘要 |
| Based on the air monitoring data during the epidemic lockdown period in Xi'an, the spatiotemporal characteristics of PM2.5 and O3 were analyzed, and the pollution sources of PM2.5, VOCs as O3 precursors, meteorological factors, and regional transport directions were discussed to explore the causes of pollution. The results showed that： ① during the lockdown period, PM2.5 and O3 increased by 20.39% and 23.72%, respectively, compared to that in the same period the previous year, whereas other parameters decreased. Compared with that in the period before and after lockdown, the co-variation trend of PM2.5 and PM10 daily averages weakened during the lockdown period, whereas the trend of O3 and NO2 showed an opposite change. Compared with that in the same period the previous year, the hourly PM2.5 values increased by 11-19 μg·m-3, and the hourly O3 values increased during the night from 18：00 to 23：00 by 10-19 μg·m-3. ② The change in pollutant concentrations showed a certain spatial clustering effect； due to the influence of topography and vegetation adsorption, PM2.5 pollution was concentrated in the northern part, whereas O3 pollution was more severe in the southern suburban area due to the weaker effect of NO2 titration in the suburbs compared to that in the urban area. ③ During the lockdown period, the contribution of mobile sources to PM2.5 decreased, whereas the contribution of fossil fuel combustion sources and industrial processes increased. The volume fraction of oxygen-containing VOCs increased due to the large-scale spraying of highly oxidizing disinfectants for epidemic prevention and control, accounting for 86.02% of the total VOCs, and acetaldehyde, propionaldehyde, and butenal were identified as priority control species among the VOCs as O3 precursors. The impact of meteorological factors on pollutant concentrations was not a simple linear relationship； in the RH < P75 range, the mean PM2.5 concentration increased with the increase in RH, whereas in the T > P25 range, the mean O3 concentration increased with the increase in temperature. Cluster analysis showed that the local contribution rate was higher during the lockdown period, accounting for 32.80%, the significant increase in O3 during the lockdown period promoted the secondary formation of PM2.5, and regional heavy pollution transport enhanced the situation of non-decrease and rebound of PM2.5. |
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