中文关键词气溶胶水溶性组分粒径分布北京化学组分 英文关键词aerosolwater-soluble componentsize distributionBeijingchemical composition

作者	单位	E-mail
杜翔	中国气象局北京城市气象研究所, 北京 100089 南开大学环境科学与工程学院, 国家环境保护城市空气颗粒物污染防治重点实验室, 天津 300071	120445687@qq.com
赵普生	中国气象局北京城市气象研究所, 北京 100089	pszhao@ium.cn
苏捷	中国气象局北京城市气象研究所, 北京 100089
董群	中国气象局北京城市气象研究所, 北京 100089 宁波北仑区气象局, 宁波 315800

中文摘要 2016~2017年，分别在夏季和冬季在北京城区利用微孔均匀分级采样器（MOUDI-122），采集环境气溶胶，并对其中水溶性离子和水溶性有机物开展了定量分析，对主要水溶性组分质量浓度粒径分布特征，以及季节和不同污染状态下的差异进行了讨论.结果表明，NH₄⁺、NO₃^-、SO₄^2-、K⁺和冬季Cl^-主要分布在积聚模态，Mg²⁺和Ca²⁺主要分布在粗粒子模态，NH₄⁺、NO₃^-、SO₄^2-在积聚模态的质量浓度最高，二次离子仍是北京地区PM_2.5污染的主要组分.SO₄^2-在夏季浓度较高，而NO₃^-、K⁺、Cl^-在冬季明显高于夏季，Mg²⁺和Ca²⁺来源较为独立，与气溶胶其他主要组分的相关性较低.夏季NO₃^-和SO₄^2-浓度昼夜差异显著，白天SO₄^2-浓度水平明显高于夜晚，夜晚NO₃^-浓度明显高于白天，且主要表现在积聚模态.污染状况下，二次离子在积聚模态和粗模态浓度增加明显，但在爱根模态中浓度降低.冬季随着污染加重，二次离子液滴模态质量中值粒径明显增大.夏季积聚模态WSOC浓度粒径分布峰值粒径明显大于冬季，0.056~0.32 μm粒径段WSOC在不同污染状态下浓度水平基本一致，在0.32 μm以上区间，污染状态下WSOC平均浓度明显高于清洁时段. 英文摘要 A micro-orifice uniform deposit impactor (MOUDI-122) was used to collect ambient aerosol at an urban site in Beijing in both winter and summer from 2016 to 2017. The water-soluble components, including ions and water-soluble organic carbon (WSOC) were analyzed. The characteristics of concentrations and size distributions for water-soluble components under different seasons and pollution conditions were determined. The results showed that NH₄⁺, NO₃^-, SO₄^2-, and K⁺ in both seasons and Cl^- in winter mainly distributed in the accumulation mode, and Mg²⁺ and Ca²⁺ primarily distributed in the coarse mode. The secondary ions were still the main components of PM_2.5 in Beijing. The concentrations of SO₄^2- were higher in summer, whereas those of NO₃^-, K⁺, and Cl^- were higher in winter. Mg²⁺ and Ca²⁺ had lower correlations with other main components of aerosols, indicating their independent sources. The average size distributions and concentration levels of NO₃^- and SO₄^2- exhibited apparent differences between daytime and nighttime in summer. During polluted periods, the concentrations of secondary ions increased in both the accumulation and coarse modes but decreased in the Aitken mode. As pollution levels increased in winter, the mass median diameters of secondary ions in the droplet mode also increased. The WSOC concentration and particle size distribution under accumulation mode in summer were significantly larger than those in winter. The distribution peaks of WSOC in accumulation mode were higher in summer than those in winter. The WSOC in particles of 0.056-0.32 μm were relatively stable under different pollution levels. However, the WSOC concentration in particles larger than 0.32 μm during polluted periods was evidently higher than that during clean periods.

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