| 北京城区大气PM2.5组分特征与典型污染过程分析 |
| 摘要点击 828 全文点击 102 投稿时间：2024-03-27 修订日期：2024-06-26 |
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| 中文关键词 北京城区 PM2.5 组分特征 PMF受体源解析 典型污染事件 |
| 英文关键词 Beijing urban area PM2.5 component characteristics PMF model typical pollution episodes |
| 作者 | 单位 | E-mail | | 景宽 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | jingkuan819@163.com | | 王友峰 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 刘保献 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 王琴 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 富佳明 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 曹阳 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 王陈婧 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 张博韬 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 沈秀娥 | 北京市生态环境监测中心, 北京 100048
大气颗粒物监测技术北京市重点实验室, 北京 100048 | shenxiue@foxmail.com |
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| 中文摘要 |
| 基于2023年全年在北京城区车公庄点位开展的大气细颗粒物（PM2.5）浓度及其组分连续在线监测,研究PM2.5浓度及其组分的演变规律和来源特征.结果表明,地壳物质为PM2.5首要组分,占比26.3%,次要组分为硝酸盐,占比为24.1%,二次无机离子（SNA）占比为43.5%,兼具沙尘和二次污染等多重影响因素.分季节来看,春、夏、秋和冬季SNA占比分别为35.3%、37.4%、54.0%和45.7%,其中2月和9月SNA占比最高（56.2%和55.1%）；春季地壳物质占比37.1%,其中4月最高达45.6%.各组分日变化差异明显,与其污染源排放、生成机制及边界层变化等有关.整体上,随着PM2.5浓度升高,有机碳（OC）和元素碳（EC）占比下降,SNA占比上升.氮氧化率（NOR）和硫氧化率（SOR）远大于0.1,且NOR随PM2.5浓度增加而增加,二次有机碳（SOC）在OC中占比为59.2%~78.0%.基于PMF的源解析结果表明,PM2.5的来源依次为：二次硝酸盐、机动车源、扬尘源、二次硫酸盐、二次有机物、工业源、燃煤源和烟花源,贡献率分别为37.4%、16.1%、13.5%、12.7%、8.6%、4.6%、3.8%和1.1%.春、夏、秋和冬季均以二次硝酸盐为主要来源,贡献率分别为37.5%、22.2%、44.5%和39.6%；夏季以二次硫酸盐和二次有机物贡献较突出,贡献率分别为21.0%和21.2%；扬尘源为春季次要来源,贡献率为26.2%.对3次典型污染事件（冬季采暖期霾污染、春季细颗粒物叠加沙尘污染和秋季PM2.5与O3复合污染）的分析结果表明,二次积累是主要污染成因,二次源贡献率分别为77.3%、53.4%和78.7%.冬季采暖期污染事件受区域燃煤源影响大,燃烧源平均贡献率为4.8%；春季污染事件受沙尘影响大,扬尘源平均贡献率为29.8%；秋季强大气氧化性促进二次转化,复合污染事件中二次硫酸盐平均贡献率为32.2%. |
| 英文摘要 |
| Based on the measurements of atmospheric fine particulate matter （PM2.5） and its components, the evolution and sources of PM2.5 were studied at the Chegongzhuang site in the Beijing urban area in 2023. The primary component was crustal matter, accounting for 26.3% of PM2.5, followed by nitrate （24.1%）. Secondary inorganic ions （SNA）, including nitrate, sulfate, and ammonium, collectively accounted for 43.5% of PM2.5. The PM2.5 composition was influenced by multiple factors, such as sandstorms and secondary pollution, in the view of its components. The proportions of SNA were 35.3%, 37.4%, 54.0%, and 45.7% in spring, summer, autumn, and winter, respectively, with the highest proportions in February and September （56.2% and 55.1%）. The proportion of crustal material was 37.1% in spring, with the highest proportion of 45.6% in April. Different diurnal variations were observed for PM2.5 components in all four seasons, owing to the different emission sources, generation mechanisms, and variations in boundary layer height. Overall, with the increase in PM2.5 concentration, the proportion of organic carbon （OC） and elemental carbon （EC） decreased, and the proportion of SNA increased. Both the nitrogen oxidation rate （NOR） and sulfur oxidation rate （SOR） were significantly higher than 0.1, and NOR increased with PM2.5. Secondary organic carbon （SOC） accounted for 59.2%-78.0% of OC. The PMF model showed that the sources of PM2.5 in Beijing in 2023 were： secondary nitrate, vehicle sources, dust sources, secondary sulfate, secondary organic matter, industrial sources, coal combustion sources, and fireworks, with the contributions of 37.4%, 16.1%, 13.5%, 12.7%, 8.6%, 4.6%, 3.8%, and 1.1%, respectively. Secondary nitrate was the main source in spring, summer, autumn, and winter, with the contributions of 37.5%, 22.2%, 44.5%, and 39.6%, respectively. In summer, secondary sulfate and secondary organic matter contributed significantly, accounting for 21.0% and 21.2%, respectively. Dust was the second-largest source in spring, with the contribution of 26.2%. Three typical pollution episodes （haze pollution in the winter heating period, fine particulate matter superposition dust pollution in spring, and PM2.5 and O3 combined pollution in autumn） were analyzed. Secondary accumulation was prominent, with the contribution rates of 77.3%, 53.4%, and 78.7% from secondary sources, respectively, for the three typical pollution episodes. Regional coal sources had a substantial effect, and the average contribution of combustion sources was 4.8% during the haze pollution in the winter heating period. For the episode in spring, the average contribution of dust sources was 29.8%. During the PM2.5 and O3 combined pollution in autumn, atmospheric oxidation strongly promoted secondary conversion, and secondary sulfate contributed 32.2%. |
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