中文关键词水溶性离子碳质组分季节变化特征济南市PM_2.5 英文关键词water-soluble ionscarbonaceous componentseasonal variationJi'nan CityPM_2.5

作者	单位	E-mail
刘晓迪	聊城大学环境与规划学院, 聊城 252000	1610140206@lcu.edu.cn
孟静静	聊城大学环境与规划学院, 聊城 252000 中国科学院地球环境研究所, 黄土与第四纪地质国家重点实验室, 西安 710061	mengjingjing@lcu.edu.cn
侯战方	聊城大学环境与规划学院, 聊城 252000 中国科学院地球环境研究所, 黄土与第四纪地质国家重点实验室, 西安 710061
李静	聊城大学环境与规划学院, 聊城 252000
邢继钊	聊城大学环境与规划学院, 聊城 252000
魏本杰	聊城大学环境与规划学院, 聊城 252000
张二勋	聊城大学环境与规划学院, 聊城 252000
刘加珍	聊城大学环境与规划学院, 聊城 252000
董杰	聊城大学环境与规划学院, 聊城 252000

中文摘要 为探究济南市大气气溶胶中化学组分的季节变化特征，于2015年夏季、冬季分别连续进行1个月的PM_2.5样品采集，并分析无机离子、碳质组分与水溶性二次有机碳（WSOC）的组成、浓度水平及来源.结果表明，济南市冬季PM_2.5的质量浓度[（158.3±95.3）μg·m^-3]约为夏季[（75.3±25.9）μg·m^-3]的2倍，在我国其浓度处于中上等水平.无机离子的总浓度呈夏低冬高的季节变化特征，其中SO₄^2-、NO₃^-、NH₄⁺是浓度最高的3种离子，且这3种离子的相关性均较好，NH₄⁺在夏季和冬季均以（NH₄）₂SO₄和NH₄NO₃的形式存在.大气中存在较高程度的SO₂和NO₂的二次氧化，其中硫氧化率（SOR）呈夏高冬低的变化特征，而氮氧化率（NOR）呈相反的季节变化特征.通过分析PM_2.5中阴、阳离子电荷平衡可知，PM_2.5呈弱碱性.基于热力学模型ISORROPIA-Ⅱ，结果表明冬季PM_2.5的酸性比夏季强.OC与EC浓度均呈夏低冬高的变化特征，由OC/EC的比值、WSOC/OC的比值和估算的二次有机碳（SOC）的浓度可知，夏季二次污染的程度比冬季更为严重.主成分分析（PCA）结果表明，济南市夏季无机离子主要来自二次氧化及生物质燃烧，而冬季无机离子主要来自煤炭燃烧及其产生的前体物经光化学氧化形成的二次污染物. 英文摘要 To investigate seasonal variations in the chemical compositions of aerosols in Ji'nan City, PM_2.5 samples were collected during summer and winter in 2015. The sampling period lasted one month during each season. PM_2.5 samples were analyzed for the composition, concentration, and sources of water-soluble inorganic ions, organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC). Results showed that mass concentrations of PM_2.5 in winter were about twice those in summer, and concentration levels varied between fine and excellent. The concentrations of total water-soluble inorganic ions were also higher in winter than in summer, with SO₄^2-, NO₃^-, and NH₄⁺ being the dominant species and well correlated with each other. NH₄⁺ in PM_2.5 mostly existed in the form of (NH₄)₂SO₄ and NH₄NO₃ in both summer and winter. There was strong secondary oxidation of SO₂ and NO₂. The sulfate oxidizing rate (SOR) was higher in summer than in winter, while the nitrate oxidizing rate (NOR) showed the opposite trend. The ratio of anions to cations in both summer and winter were less than one, suggesting that PM_2.5 were slightly alkaline. The ISORROPIA-Ⅱ mode showed that acidity in winter was stronger than in summer. Concentations of OC and EC were both higher in winter than in summer. The ratios of OC to EC and WSOC to OC and estimated concentrations of secondary organic carbon (SOC) showed that secondary pollution was more serious in winter than in summer. Principal component analysis(PCA)indicated that the major sources contributing to inorganic ions were secondary oxidation and biomass burning in summer, and coal combustion and secondary pollutants formed by chemical oxidation of precursors emitted from coal combustion in winter.

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