中文关键词PM_2.5水溶性无机盐季节变化日变化来源 英文关键词PM_2.5water-soluble inorganic ionsseasonal variationdiurnal variationsource

作者	单位	E-mail
高韩钰	河北农业大学资源与环境科学学院, 保定 071001	mona327@163.com
魏静	河北农业大学资源与环境科学学院, 保定 071001	weijing_199@163.com
王跃思	中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室, 北京 100029

中文摘要 为研究北京偏南地区细颗粒物（PM_2.5）中水溶性无机离子的变化特征，利用大气细颗粒物快速捕集系统及化学成分分析系统RCFP-IC，于2016年对北京南郊区大兴PM_2.5中9种水溶性无机离子（Cl^-、NO₂^-、NO₃^-、SO₄^2-、Na⁺、NH₄⁺、K⁺、Mg²⁺和Ca²⁺）展开为期1 a的连续在线观测.结果表明，观测期间，9种水溶性无机离子总质量浓度为38.6 μg·m^-3，并呈现冬春高，夏秋低的特征，浓度水平高低顺序为SO₄^2- > NO₃^- > NH₄⁺ > Ca²⁺ > NO₂^- > Cl^- > Na⁺ > K⁺ > Mg²⁺；在冬季，SO₄^2-、NO₃^-和NH₄⁺浓度占比高达75.7%；春季次之，为72.8%；夏季最低，仅为60.2%.并且随着空气污染的加剧，SO₄^2-、NO₃^-和NH₄⁺浓度显著增加，这表明SO₄^2-、NO₃^-和NH₄⁺与空气质量的恶化密切相关，但相比NO₃^-和NH₄⁺，SO₄^2-在二次离子形成过程中占据主导地位；SO₄^2-、NO₃^-和NH₄⁺存在显著的日变化特征，SO₄^2-统计日变化为双峰型，峰值分别出现在10：00和18：00左右，而NO₃^-和NH₄⁺呈单峰型，峰值出现在10：00左右.基于后向轨迹聚类分析结果发现，对南郊区污染有影响的气团主要有3类，分别来自东南方向、西部和来自蒙古高原的高空气团，东南方向气流会加重南郊区水溶性盐的累积，而偏北气流有利于污染物扩散和稀释；基于主成分分析发现，北京南郊区水溶性盐的污染来源分别为二次源、燃煤源和土壤风沙尘及建筑扬尘的混合源.利用潜在源贡献因子分析法对南郊区冬季水溶性盐的潜在污染源区进行分析发现，影响大兴水溶性盐浓度潜在源区主要分布在南郊区的东南部. 英文摘要 In order to study the variation of water-soluble inorganic ions in the four suburbs of Beijing using the atmospheric fine particulate matter rapid trapping system and chemical composition analysis system (RCFP-IC), we carried out measurements for nine water-soluble inorganic ions (Cl^-, NO₂^-, NO₃^-, SO₄^2-, Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺) in PM_2.5 with continuous on-line observations for one year in Beijing's southern suburbs in 2016. The transport process of pollutants and the potential sources of pollutants were evaluated by combining a trajectory clustering method and potential source contribution factor analysis method (PSCF). During the observation period, the total concentration of the nine water-soluble inorganic ions was 38.6 μg ·m^-3, and results showed that the concentration in winter and spring was high and in summer and autumn was low. The order of the concentration from high to low was SO₄^2- > NO₃^- > NH₄⁺ > Ca²⁺ > NO₂^- > Cl^- > Na⁺ > K⁺ > Mg²⁺. In winter, the SO₄^2-, NO₃^- and NH₄⁺ accounted for 75.7% of the total measured water-soluble ions, followed by 72.8% in spring and 60.2% in summer. With an increase in air pollution, the concentrations of SO₄^2-, NO₃^-, and NH₄⁺ increased significantly, indicating that SO₄^2-, NO₃^-, and NH₄⁺ were closely related to the deterioration of air quality. SO₄^2- was dominant in the formation of secondary ions compared to NO₃^- and NH₄⁺; and SO₄^2-, NO₃^-, and NH₄⁺ had significant diurnal variations. The diurnal variation of the SO₄^2- statistic (hours) was bimodal, and the peak values were at about 10:00 and 18:00. The diurnal variation of NO₃^- and NH₄⁺ had single peaks, with the peak appearing at 10:00. The trend of the diurnal variation for these two ions was similar. Finally, the sources of pollution in the southern suburbs of Beijing mainly included secondary sources, coal-fired sources, and mixed sources of dust and dust. The main potential source of pollution in the southern suburbs was in the southeastern part of the observation site, while the northeastern airflow was favorable for the diffusion and dilution of pollutants.

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