• 关键词：颗粒物  化学组分  粒径分布  垂直分布

• 基金项目：天津市科技计划项目（No.14ZCDGSF00027，15YFYSSF00030）；国家科技支撑计划（No.2014BAC23B01，2014BAC23B03）

• 孙韧
• 1. 天津大学环境科学与工程学院, 天津 300072;2. 天津市环境监测中心, 天津 300191

• 肖致美
• 天津市环境监测中心, 天津 300191

• 韩素芹
• 天津市气象科学研究所, 天津 300074

• 陈魁
• 天津市环境监测中心, 天津 300191

• 丁净
• 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

• 吴建会
• 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

• 张裕芬
• 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

• 冯银厂
• 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

• 摘要：为了解天津市冬季近地层颗粒物垂直分布特征，于2013年12月23日-2014年1月18日，利用Andersen撞击式采样器在天津大气边界层观测站采集10 m和220 m高度颗粒物样品，分析了水溶性离子、碳组分.结果表明，不同天气下不同粒径颗粒物质量浓度分布均呈双峰形，峰值出现在1.1~2.1 μm和9.0~10 μm粒径段.PM₁₀浓度均随高度的增加而降低，污染日和清洁日最大浓度峰值分别出现在1.1~2.1 μm、9.0~10 μm粒径段.污染日SO₄^2-、NO₃^-、NH₄⁺等二次离子质量浓度、百分占比及OC/EC的比值均随高度的上升而增加；清洁日二次离子质量浓度随着高度的上升而降低，但百分占比随着高度的上升而增加，OC/EC的比值均随高度的上升基本保持稳定.污染日SO₄^2-、NO₃^-、Cl^-质量浓度及百分占比均较清洁日增加明显，燃煤、机动车及二次离子为颗粒物的主要来源，并在220 m高度二次污染较重.污染日和清洁日下NO₃^-/SO²₄^-的比值均随着高度的上升而增加，低层机动车排放对亚微米模态（<1 μm）贡献明显，而对于粗粒径段，燃煤源的贡献则大于机动车.污染日和清洁日二次离子、OC、EC主要富集于细粒子，Ca²⁺、Mg²⁺、Na⁺等一次离子主要富集于粗粒子.

• Abstract：To better understand vertical distributions characteristics of particulate matter (PM) at surface layer during winter time in Tianjin, size-resolved PM samples were collected by Andersen cascade impactor at heights of 10 m and 220 m from a 255 m meteorological observation tower from Dec 23^rd, 2013 to Jan 18^th, 2014 in Tianjin, China. The concentrations of water-soluble ions and organic and elemental carbon in PM were determined. Size-distribution are bimodal pattern at 10 m and 220 m both peaked at 1.1~2.1 μm and 9~10 μm. PM₁₀ concentration showed a decreasing trend with increasing height, and the maximum value appeared at 1.1~2.1 μm on pollution days and 9~10 μm on clear days, respectively. Secondary ions (SO₄^2-, NO₃^- and NH₄⁺) concentrations, their fractions in PM₁₀ and OC/EC ratio all showed increasing trends with the increase of height on pollutions days, while increasing secondary ions fractions and decreasing secondary ions concentrations were found on clear days, and OC/EC ratio remained stable with height. SO₄^2-, NO₃^- and Cl^- concentrations and their fractions in PM₁₀ were significantly higher on pollution days than clear days. Coal combustion, motor vehicle exhausts and secondary ions were the main sources for PM on pollution days and secondary ions showed a higher ratio in PM₁₀ at 220 m than 10 m. Values of NO₃^-/SO²₄ showed increasing trends with the increase of height both on pollution and clear days. Contribution from motor vehicle exhausts was greater than coal combustion for submicron PM, and lower for coarse PM. Secondary ions, OC, and EC all mainly dominated in the fine mode on pollution and clear days, while Ca²⁺, Mg²⁺ and Na⁺ mainly dominated in the coarse mode.

• Key words：particulate matter  chemical compositions  size distribution  vertical distribution

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