武汉市大气PM_(2.5)中有机酸的季节变化及其来源解析  

Seasonal Variation and Source of Carboxylic Acids in PM_(2.5) in Wuhan,China

作　　者：郭浩天[1] 周家斌[1] 余文洋 肖经汗[1] 

机构地区：[1]武汉理工大学资源与环境工程学院,湖北武汉430070

出　　处：《环境科学与技术》2014年第4期90-95,共6页Environmental Science & Technology

基　　金：国家自然科学基金(41173092)

摘　　要：经过预处理的样品用BSTFA／TMCS衍生化试剂衍生后，采用GC—MS技术对武汉市一年四季3个不同类型采样点中大气气溶胶中有机酸进行定量分析。共测定武汉市大气PM2.5中22种饱和脂肪酸（C11～C32）、油酸（C181）、亚油酸（C182）和8种二元羧酸（di-C2-di—C9）。3个采样点四季脂肪酸均呈现出明显的碳偶数优势，其中最丰富的物种均为棕榈酸（年均值ID：85．86ng／m3，DT：56．43ng／m3，BG：52．39ng／m3）和硬脂酸（年均值ID：57．05ng／m3，DT：32．68ng／m3，BG：37．37ng／m3）。同时通过c18l与cl∞的比值用来判断武汉市不同季节、不同类型污染源气溶胶的老化程度。二元羧酸中最丰富的物种为草酸（年均值ID：254．62ng／m3，DT：367．38ng／m3，BG：235．19ng／m。），其次为丁二酸（年均值ID：214．70ng／m3，DT：312．44ng／m3，BG：168．46ng／m3）、丙二酸（年均值ID：103．45ng／m3，DT：70．56ng／m3，BG：44．48ng／m3），二元羧酸总浓度呈现出明显的季节变化，表现为夏季〉春季〉秋季〉冬季。通过di—C2与di—C3之比之来判断二次源对不同类型采样点气溶胶的贡献程度。主成分分析法结果显示化石燃料燃烧、机动车排放及光化学氧化、生物质燃烧、肉类烹饪是武汉市大气气溶胶中有机酸的主要来源。The prepared samples were derivatized with BSTFA/TMCS, followed by GC-MS analysis. Concentrations of 22 fatty acids （C11-C32）, 2 unsaturated fatty acids and 8 dicarboxylic acids （di-C2-di-Cg） were determined. Fatty acids show the dominance of even carbon number acids to odd carbon number acid isomers in all seasons in three sampling sites, in which palmitic acid （ annual average ID ： 85.86 ng/m3, DT： 56.43 ng/ma, BG ： 52.39 ng/m3） and stearic acid （ annual average ID ： 57.05 ng/m3, DT：32.68 ng/m3, BG：37.37 ng/m3） were the most abundant species. The ratios of oleic acid to stearic acid were used to discuss the aging of the aerosols in different seasons and different sampling sites. Oxalic acid was found as the most dominant dicarboxylic acid （annual average ID： 254.62 ng/m3, DT： 367.38 ng/m3,BG：235.19 ng/m3）, followed by succinic acid （ annual average ID： 214.70 ng/m3, DT： 312.44 ng/ma, BG： 168.46 ng/m3） and malonic acid （ annual average ID： 103.45 ng/m3, DT：70.56 ng/m3,BG：44.48 ng/m3）.Total concentration of dicarboxylic acids displayed obvious seasonal variation, with the highest in summer following by spring and fall and the lowest in winter. The ratios of malonic acid to succinic acid indicated the secondary source＇s contributions of three different sampling sties. PCA analysis reveals that fossil fuel combustion, traffic-related emissions, secondary photochemical products and foot cooking are major contributors of carboxylic acids in PM2.5 in Wuhan.

关 键 词：PM2 5 有机酸 GC—MS 气溶胶老化 二次气溶胶 

分 类 号：X513[环境科学与工程—环境工程]