【摘要】 甲酸、乙酸和草酸是对流层大气低分子有机酸的重要组成成分,对大气降水的酸度有一定的贡献。2012年3月至2013年8月间共采集上海市闸北区大气降水样品54个,测定了样品低分子有机酸成分和浓度并讨论了其与降雨量、降水pH、降水电导率的变化规律。结果表明,大气降水总体呈酸性。大气降水中最主要的有机酸成分为甲酸、乙酸和草酸,三种酸的加权平均浓度依次为8.3、6.1和1.1μmol/L,三种有机酸的最高值均发生在春季。有机酸总量平均为15.5μmol/L,占阴离子总浓度的13.7%,对降水自由酸度的平均贡献值为3.6%。有机酸含量的季节变化规律显示植物生长释放、生物质燃烧和汽车尾气排放是有机酸的主要来源,春季有机酸的浓度高值可能与相对较低的降雨量,较高降水pH以及其他大气污染输入途径有关。甲酸与乙酸具有极显著的相关性,相关系数0.86。表明甲酸与乙酸具有相似的来源或者不同来源的相似源强。有机酸还与传统检测的阴阳离子共同组成了降水阴阳离子的平衡和EC值的平衡,在降水R1与R2的平衡计算之中,应考虑有机酸的影响。更多还原

【Abstract】 As low molecular weight carboxylic acids,the most abundant carboxylic acids were formic acid,acetic acid and oxalic acid,which made certain contribution to the precipitation acidity.We collected 54 samples during March 2012 to August 2013 in Shanghai Zhabei area,by measuring the component and concentration,and the relationship between the change law of the precipitation,pH and conductivity.The results showed that the meteoric water was acidic.The main composition of carboxylic acids in precipitation were formic acid,acetic acid and oxalic acid,which the weighed concentration average separately were 8.3、6.1and 1.1 μmol/L,the peak concentration was in spring.The average of the total carboxylic acids was 15.5 μmol/L,which accounted 13.7 % of the anion,and 3.6 % of the contribution of the free action of the precipitation.The law of seasonal change of carboxylic acids showed that plants release,biomass burning and automotive exhaust emission auto-exhaust were the main source of carboxylic acids.The higher value of carboxylic acids in spring may be related to the lower rainfall amount,higher pH and input pathway of other pollution.Formic acid and acetic acid has the extremely significant correlation,the correlation coefficient was 0.86 which showed that the formic acid and acetic acid had similar source.The balance of anion-cation and EC value in Precipitation was composited by both carboxylic acids and inorganic ion tranditionally detected,in the calculation of R1 and R2,the impact of carboxylic should be considered.更多还原