• 关键词：大气降水  化学组分  趋势分析  富集因子  来源分析

• 基金项目：国家自然科学基金项目(No.41205089, 21207069);天津市重大科技专项项目(No. 14ZCDGSF0027)

• 陈魁
• 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

• 李鹏
• 天津市环境监测中心, 天津 300191

• 孙韧
• 天津市环境监测中心, 天津 300191

• 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：2001—2013年对天津市降水样品进行了采集,分析了pH、电导率(EC)、主要离子浓度(SO₄^2-、NO₃^-、Cl^-、F^-、NH₄⁺、Ca²⁺、Mg²⁺、Na⁺、K⁺).结果表明:2001—2013年,降水的雨量加权平均pH、EC分别为5.48、87 μS · cm^-1.降雨的pH、EC及总离子当量浓度呈现上升趋势,酸雨频率呈现下降趋势.降水中各离子雨量加权平均当量浓度排列顺序为:SO₄^2->Ca²⁺>NH₄⁺>NO₃^->Cl^->Mg²⁺>Na⁺>F^->K⁺,SO₄^2-、Ca²⁺、NH₄⁺和NO₃^-是降水中的主要离子,占离子总量的84.8%.SO₄^2-雨量加权平均当量浓度表现为先轻微上升,后显著下降趋势.NO₃^-、Ca²⁺雨量加权平均当量浓度表现为明显上升趋势.NH₄⁺雨量加权平均当量浓度显示为下降趋势.F^-、Cl^-、K⁺、Mg²⁺、Na⁺等雨量加权平均当量浓度变化趋势基本保持平稳.SO₄^2-对总阴离子的分担率、NH₄⁺总阳离子的分担率均呈现下降趋势.NO₃^-对总阴离子的分担率、Ca²⁺对总阳离子的分担率均呈现明显上升趋势.呈现出明显上升趋势.富集因子计算结果表明:Ca²⁺主要来自地壳.Mg²⁺和K⁺部分来自海源输入,但绝大部分来自地壳.大部分Cl^-来自海源的输入,其余小部分来自地壳和人为排放.降水中SO₄^2-、NO₃^-主要来自人为活动.

• Abstract：Precipitation samples were collected from 2001 to 2013 in Tianjin. All the samples were analyzed for pH, electrical conductivity(EC)and main ionic (SO₄^2-,NO₃^-,Cl^-, F^-,Ca²⁺,NH₄⁺, Mg²⁺,Na⁺ and K⁺) concentrations. Average annual volume-weighted mean pH and EC during 2001—2013 were 5.48 and 87 μS · cm^-1, respectively. Increasing trends were found for pH, EC and total ionic concentrations, while decreasing trend for frequency of acid in precipitation. The volume-weighted mean equivalent concentration of precipitation components followed the order SO₄^2->Ca²⁺>NH₄⁺>NO₃^->Cl^->Mg²⁺>Na⁺>F^->K⁺. SO₄^2-,Ca²⁺,NH₄⁺ and NO₃^- were the dominant compositions in percipitation, accounting for 84.8% of the total ions. A trend of SO₄^2- increased slightly followed by significant decrease. Significant increasing trends for NO₃^-, Ca²⁺ and decreasing trend for NH₄⁺ were observed, while F^-,Cl^-, K⁺,Mg²⁺ and Na⁺ levels remained relatively stable. Decreasing trend was found for contributions of to total anion mass and to total cation mass. significant increasing trends were found for contributions of to total anion mass and to total cation mass. The ratios of/and/showed increasing trends. Enrichment factor was used to assess sources of major ions. Ca²⁺ was mainly originated from crust source. Mg²⁺ and K⁺ were partly from the marine source while the contribution of the soil source was considerable. Cl^- mainly came from marine source, with small parts from anthropogenic sources. SO₄^2-and NO₃^- were mostly attributable to anthropogenic sources.

• Key words：atmospheric precipitation  chemical composition  trends analysis  enrichment factor  sources apportionment

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