| 贵州安顺雨季降水中低分子有机酸研究 |
| 摘要点击 1556 全文点击 1127 投稿时间：2008-03-29 修订日期：2008-05-19 |
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| 中文关键词 大气降水 有机酸 来源 安顺 |
| 英文关键词 precipitation carboxylic acids sources Anshun |
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| 中文摘要 |
| 为了解贵州安顺地区大气降水中低分子有机酸的化学组成特征， 2007年6～10月共采集降水40次，对降水样品进行了pH值、电导率、水溶性无机阴离子和低分子有机酸的测定.结果表明，安顺地区的大气降水的pH值在3.57～7.09之间，平均值为4.57.最主要的有机酸组成为乙酸、甲酸和草酸，它们的雨量平均浓度依次为6.75、 4.61和2.05 μmol·L-1.有机酸在6月和7月的浓度明显高于其他月份，表明有机酸可能来源于植物生长释放或者其前驱物的光化学氧化.有机酸对降水自由酸的贡献率平均为32.2%，明显高于贵阳市.同时，甲酸与乙酸和草酸存在显著相关关系（p=0.01），相关系数分别为0.663和0.503，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，而草酸的前驱物可能与甲酸具有相似的排放特征.观测期间，安顺地区有机酸的湿沉降通量为2.10 mmol/m2，主要集中在降雨频率和雨量相对较高的夏季，此时有机酸的浓度和有机酸对大气降水自由酸的贡献都较大，因此控制安顺地区夏季有机酸的排放对于此地区的酸雨防治工作显得尤为重要. |
| 英文摘要 |
| 40 rainwater samples were collected at Anshun from June 2007 to October 2007 and analysed in terms of pH values, electrical conductivity,major inorganic anions and soluble low molecular weight carboxylic acids. The results showed that pH of individual precipitation events ranged from 3.57-7.09 and the volume weight mean pH value was 4.57. The most abundant carboxylic acids were acetic (volume weight mean concentration 6.75 μmol·L-1) and formic (4.61 μmol·L-1) followed by oxalic (2.05 μmol·L-1). The concentration levels for these three species during summer especially June and July were comparatively high; it implied that organic acids in Anshun may came primarily from emissions from growing vegetations or products of the photochemical reactions of unsaturated hydrocarbons. Carboxylic acids were estimated to account for 32.2% to the free acidity in precipitation.The contribution was higher than in Guiyang rainwater,which indicated contamination by industry in Guiyang was more than in Anshun. The remarkable correlation(p=0.01) between formic acid and acetic acid suggest that they have similar sources or similar intensity but different sources.And the remarkable correlation(p=0.01) between and formic acid and oxalic acid showed that the precursors of oxalic acid and formic acid had similar sources. During this period, the overall wet deposition of carboxylic acids were 2.10 mmol/m2.And it appeared mainly in the summer,during which both concentration and contribution to free acidity were also relatively high.Consequently, it was necessary to control emission of organic acids in the summer to reduce frequence of acid rain in Anshun. |
