| 2022年北京市城区PM2.5水溶性离子含量及其变化特征 |
| 摘要点击 3107 全文点击 81 投稿时间：2023-09-06 修订日期：2023-11-17 |
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| 中文关键词 大气细颗粒物（PM2.5） 水溶性离子 二次无机离子（SNA） 质量浓度 变化特征 |
| 英文关键词 atmospheric fine particles （PM2.5） water-soluble inorganic ions secondary inorganic ions （SNA） concentration variation characteristics |
| 作者 | 单位 | E-mail | | 陈圆圆 | 北京市生态环境监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | 214151318@qq.com | | 崔迪 | 北京市生态环境监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 赵泽熙 | 北京市生态环境监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 常淼 | 北京市生态环境监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 景宽 | 北京市生态环境监测中心, 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, 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, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | 4380578@qq.com |
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| 中文摘要 |
| 为探究北京市大气细颗粒物（PM2.5）水溶性离子含量及其变化特征,有针对性地提出污染防治方案,对2022年全年PM2.5水溶性离子、气态前体物（SO2、NO2）和气象因素（温度、RH）进行分析测定.结果表明,北京市城区PM2.5中占比最高的水溶性离子为NO3-、NH4+和SO42-,占PM2.5的52.7%,ρ（PM2.5）（33.2 μg·m-3）和ρ（SNA）（18.9 μg·m-3）低于历史研究结果,但SNA占比（52.7%）、SOR（0.45）和NOR（0.15）高于历史研究结果,体现出北京市细颗粒物污染得到明显改善,但仍具有较强的二次污染特征.NO3-/SO42-为2.2,高于历史及附近省市研究结果,反映出移动源的影响不断扩大.从季节变化上看,PM2.5呈现秋高夏低的变化特征,秋、春、冬这3个季节NO3-的占比最高,夏季SO42-占比最高,而NH4+在各季节占比变化不大.NOR与SOR的季节变化规律几乎相反,反映出二者的转化形成因素存在差异.北京城区SNA的主要存在形式为NH4NO3和（NH4）2SO4,其中冬季阴阳离子中和度最高,夏季阳离子NH4+稍显不足,而春秋两季NH4+处于过量状态,北京城区为富氨环境.从污染级别看,水溶性离子质量浓度均随污染加重有不同程度的增长,增长最快的是SNA,其在PM2.5中占比出现先上升后稳定的变化特征.从空间分布特征来看,中心城区和东南西北部郊区的SNA质量浓度大小均为：NO3->SO42->NH4+,体现了以NO3-为主导的污染特征；SNA对PM2.5的贡献率最高的区域发生在东部、中心城区和传输点,表明在中心城区和东部地区二次反应相对活跃,同时区域传输也是二次离子的重要来源. |
| 英文摘要 |
| To explore the content and variation characteristics of water-soluble ions of atmospheric fine particles (PM2.5) in a Beijing urban area and put forward the pollution prevention and control scheme, the water-soluble ions, gaseous precursors (SO2, NO2), and meteorological factors (temperature, RH) of PM2.5 in 2022 were analyzed and determined. The results showed that the water-soluble ions with the highest proportion in PM2.5 in the Beijing City urban area were NO3-, NH4+, and SO42-, accounting for 52.7% of PM2.5. The mass concentrations of PM2.5 and SNA were lower than the historical results, whereas the proportion of SNA, SOR, and NOR was higher than the historical results. This showed that the fine particulate matter pollution in Beijing has been significantly improved, but it still has strong secondary pollution characteristics. NO3-/SO42-(2.2) was higher than those of historical and nearby provinces and cities, reflecting the expanding influence of mobile sources. In terms of seasonal variation, PM2.5 showed the characteristic of high in autumn and low in summer. The proportion of NO3- was the highest in autumn, spring, and winter; the proportion of SO42- was the highest in summer; and the proportion of NH4+ changed little in each season. The seasonal variation rules of NOR and SOR were almost opposite, which reflected the difference in transformation factors between NOR and SOR. The main forms of SNA in the Beijing urban area were NH4NO3 and (NH4)2SO4. The neutralization degree of cations and anions was the highest in winter, the cation NH4+ was slightly insufficient in summer, and NH4+ was in excess in spring and autumn. The Beijing urban area was an ammonia-rich environment. In terms of pollution level, RH, particulate matter moisture, and water-soluble ions mass concentration all increased with the increase in pollution level, and SNA increased fastest, with its proportion in PM2.5 increasing first and then stabilizing, whereas the contribution rate of other water-soluble ions decreased gradually. In terms of spatial distribution, the mass concentration relationship of SNA at the central urban area and suburbs was NO3- > SO42- > NH4+, which reflected the pollution characteristics dominated by NO3-. The highest contribution rate of SNA to PM2.5 occurred in the eastern region, the central urban area, and the transmission point, indicating that the secondary reaction was relatively active in the central urban area and the eastern region, and the regional transport was also an important source of secondary ions. |
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