Urban and rural observations of carboxylic acids in rainwater in Southwest of China: the impact of urbanization
Urban and rural observations of carboxylic acids in rainwater in Southwest of China: the impact of urbanization
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DOI：
10.1007/s10874-010-9151-4
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发表时间：
2009-04
影响因子：
2
通讯作者：
Gang Xu;X. Lee;Yingchun Lv
中科院分区：
文献类型：
--
作者：
Gang Xu;X. Lee;Yingchun Lv
采用离子色谱法对贵阳和尚中两地雨水中7种羧酸进行了连续13个月的同时测定。结果表明，甲酸、乙酸和草酸是三种主要的羧酸。贵阳市的体积加权平均浓度分别为14.24、9.35、2.79 μmol/L，上中市的体积加权平均浓度分别为4.95、1.35、2.31 μmol/L。贵阳地区生长季土壤羧酸浓度存在明显的日变化规律（白天>夜间，t检验，p< 0.05）。上种在生长季中这些酸的浓度高于非生长季。生长中的植被或土壤的直接排放可能是农村地区酸的主要来源。而贵阳市则相反，非生长季的人为污染源是主要原因。通过与20年前的数据比较，我们计算出贵阳地区至少有42%的乙酸和69%的甲酸来源于人为污染。气相中甲酸盐/乙酸盐比值大于1，说明贵阳地区羧酸的主要来源是人类活动和/或天然来源的不饱和烃的氧化。而上中地区气相中的F/A值小于1，表明其为生物源的直接排放。草酸在这两个网站的数量相似，表明酸的共同来源。
Seven carboxylic acids in rainwater were simultaneously determined using ion chromatography for 13 months in two different sites, Guiyang and Shangzhong, southwest of China. Results showed formic, acetic and oxalic acids were the three predominant carboxylic acids. Their volume-weighted average concentrations were 14.24, 9.35, 2.79 μmol/L in Guiyang and 4.95, 1.35, 2.31 μmol/L in Shangzhong, respectively. A distinctive diurnal pattern in carboxylic acid concentrations (daytime>nighttime,ttest,p< 0.05) was observed during the growing season in Guiyang. Shangzhong witnessed higher concentration of these acids during the growing season than that during the non-growing season. Direct emissions from growing vegetation or soils probably account for the main provenance of the acids in the rural area. However, the opposite trend were found in Guiyang and the anthropogenic sources during the non-growing season were the main reason. By comparison of our result with the previous data about 20 years ago, we calculated that at least 42% of acetic acids and 69% of formic acid originated from the anthropogenic sources in Guiyang. Furthermore, the ratio of formate/acetate in gas phase larger than 1 suggest the oxidation of unsaturated hydrocarbons from the human activity and/or natural sources were the main origin of carboxylic acids in Guiyang. While The F/A ratio in gas phase was less than 1 in Shangzhong which indicate the direct emissions from biogenic sources. Oxalic acid was in similar amounts in both sites, indicating the common source of the acid.