| 贵州省遵义地区降水中低分子有机酸及其来源 |
| 摘要点击 2283 全文点击 2811 投稿时间：2007-09-08 修订日期：2007-11-20 |
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| 中文关键词 甲酸 乙酸 亨利定律 离子色谱 湿沉降 酸雨 贵州 |
| 英文关键词 formic acid acetic acid Henry's law ion chromatograph wet deposition acid rain Guizhou |
| 作者 | 单位 | | 江伟 | 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳550002
中国食品发酵工业研究院酿酒工程技术研究发展部, 北京100027
中国科学院研究生院,北京 100049 | | 李心清 | 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳550002 | | 曾勇 | 贵州省遵义市环境监测中心站, 遵义563000 | | 黄荣生 | 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳550002 | | 谭凌 | 贵州省遵义市环境监测中心站, 遵义563000 | | 徐刚 | 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳550002
中国科学院研究生院, 北京100049 | | 王兵 | 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵阳550002
中国科学院研究生院, 北京100049 |
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| 中文摘要 |
| 甲酸和乙酸是大气对流层中广泛存在的低分子有机酸.降水中有机酸的研究是认识C、H、O等元素生物地球化学循环和酸雨成因的重要内容.贵州省遵义地区是我国酸雨高发地区，在遵义市进行了为期1 a的降水采集，并利用离子色谱法和原子吸收法分别对降水中主要阴离子(包括有机和无机)和阳离子进行了测定.结果显示，pH的年均值为4.11，表明遵义市酸雨形势依然严峻；甲酸和乙酸的雨量加权平均值分别为9.29 μmol·L-1 (范围：0.15～46.14 μmol·L-1) 和6.47 μmol·L-1 (范围：0.02～19.11 μmol·L-1)，占阴离子总量的4.10 %，二者的相关系数达到0.86，说明甲酸和乙酸具有共同的来源.在一次降雨事件中，有机酸的浓度一般随降雨时间的延长而降低，但在降雨中后期有时会出现上升的现象，表明有机酸主要来自云下淋滤作用，少数情况下来自大气远距离的传输.遵义市区的山间盆地地形、高湿度、低风速、以尘埃为主的大气污染物等特点为有机酸来源于当地创造了条件.应用气液平衡的原理，提出了降水中甲酸、乙酸比值(F/A)aq的有机酸来源判定方法.发现遵义降水中的有机酸春季和冬季主要来自人类活动的释放，夏季和秋季则主要来自植物的释放. |
| 英文摘要 |
| Formic (HCOOH) and acetic (CH3COOH) acids are ubiquitous in troposphere. Studies on the low-molecular carboxylic acids help shed light on the biogeochemical cycles of carbon, hydrogen and oxygen, as well as on the formation of acid precipitation. As a city with severe acid precipitation, the city Zunyi in north Guizhou province, provide a typical background for gaining insight into the organic geochemistry in the heavily polluted atmospheric environment. We collected the precipitation in the downtown city for a whole year on the event basis, and measured inorganic and organic anions with ion chromatograph and cations with atomic absorption spectroscopy. The data demonstrate an annual average pH of 4.11, a clear indication of the acid atmosphere. The volume-weighted mean concentrations of ［HCOO-］T and ［CH3COOCOO-］T were 9.29 μmol·L-1 (ranged from 0.15 μmol·L-1 to 46.14 μmol·L-1) and 6.47 μmol·L-1 (ranged from 0.02 μmol·L-1 to 19.11 μmol·L-1) respectively, accounting for 4.10 % of the total anions. With a coefficient of 0.86, formic is significantly correlated with acetic acid, suggesting that both acids share common sources. The acids often decrease with time in a precipitation event, with occasional increases in the middle and last stages, indicating that the organic acids are primarily scavenged from blow cloud, with limited amount from the long distance transportation. The close range provenance of organic acids is facilitated by the local environmental condition, which is characterized by the mountain-enclosed valley with high humidity, low wind speed, and high atmospheric dust content. Based on the Henry's Law, we proposed the ratio of formic and acetic acids in the precipitation (F/A)aq as the indicator of the sources, and thus found that the anthropogenic sources are responsible for the organic compounds in the Spring and Winter, while vegetation emissions claim the sources in the Summer and Autumn. |
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