| 近年北京市环境空气臭氧及其背景浓度的对比分析 |
| 摘要点击 1433 全文点击 222 投稿时间：2024-03-24 修订日期：2024-05-22 |
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| 中文关键词 北京 臭氧（O3） 浓度变化 区域背景 本地生成 |
| 英文关键词 Beijing ozone（O3） concentration variations regional background local generation |
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| 中文摘要 |
| 为了解北京市近年来O3污染变化趋势及区域背景的贡献,基于2018~2022年北京市34个站点的O3在线监测数据,对比分析了北京市及其城区点、郊区点、清洁点、区域点和交通点等不同类型点位的O3浓度时序变化和超标情况,并利用美国德克萨斯州环境质量委员会（TCEQ）提出的区域背景估算方法计算区域背景（没有前体物排放时的O3浓度）和本地生成对O3的贡献率. 结果表明,在2018~2022年期间,2019年北京市O3体积分数年评价值最高,2021年最低,2022年出现反弹；除交通点外,北京市及其他各类型点位O3体积分数均呈下降趋势. 各点位O3月评价值最高均出现在6月,清洁点位月评价值常高于其他点位. O3超标率和重度污染天数占比均呈波动变化,清洁点更易出现O3重污染天. O3超标天中以轻度污染为主,2020~2022年重度污染天O3平均体积分数均高于2019年. 为剔除NO对O3“滴定”效应的影响,TCEQ法采用总氧化剂Ox（Ox=O3+NO2）代替O3进行估算,结果表明北京市区域背景和本地生成均呈下降趋势,区域背景对O3的贡献明显高于本地生成；但由于光化学活动的增强,夏季区域背景的贡献有所降低. 总体而言,虽然2018~2022年北京市O3体积分数呈现下降趋势,但重污染天O3没有表现出同样的变化趋势. 为实现“十四五”基本消除重污染天气目标,并有效控制O3污染,建议北京市在加强本地O3前体物排放管控的同时,进一步优化京津冀及周边区域的大气污染联防联控机制,减少区域背景对O3污染的贡献. |
| 英文摘要 |
| To understand the trends of O3 pollution changes and the contribution of regional background in Beijing in recent years, this study investigated the temporal variations of O3 mixing ratios and the exceedance of O3 pollution at different types of sites, such as urban, suburban, clean, regional, and transportation sites, based on the online monitoring data from 34 stations in Beijing from 2018 to 2022. The regional background estimation method proposed by the Texas Commission on Environmental Quality （TCEQ） was applied to calculate the contributions of regional background and local generation to O3. The results showed that the annual average value of O3 mixing ratios in Beijing was the highest in 2019, the lowest in 2021, and rebounded in 2022, from 2018 to 2022. Except for transportation sites, O3 mixing ratios in Beijing and all other types of sites exhibited decreasing trends. The highest monthly average value of O3 occurred in June and the monthly average values of clean sites were often higher than those of other sites. The proportions of O3 exceedance days and heavily polluted days varied over the last five years and days with high O3 pollution more often occurred at the clean site. The O3 exceedance days were mostly dominated by light pollution and the average O3 mixing ratios on heavily polluted days in 2020-2022 were greater than those in 2019. To exclude the influence of NO on the “titration” effect of O3, the TCEQ method was estimated by using the total oxidant Ox （Ox=O3+NO2） instead of O3. The results showed that both the regional background and the local generation in Beijing showed decreasing trends and the contribution of the regional background was significantly higher than that of the local generation. However, the contribution of the regional background decreased in the summer due to the enhancement of the photochemical activities. In general, although the O3 mixing ratios in Beijing had been decreasing from 2018 to 2022, no such trend was observed in the O3 mixing ratios on heavily polluted days. To achieve the goal of basically eliminating heavily polluted days in the 14th Five-Year Plan and to effectively control O3 pollution, it is recommended that Beijing should further optimize the joint prevention and control of atmosphere pollution in Beijing-Tianjin-Hebei and neighboring regions to reduce the contribution of regional background to O3 pollution while strengthening the control of local O3 precursor emissions. |
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