| 长江源区降水氢氧稳定同位素特征及水汽来源 |
| 摘要点击 2278 全文点击 757 投稿时间：2018-11-19 修订日期：2019-01-06 |
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| 中文关键词 青藏高原 长江源区 大气降水 稳定同位素 水汽来源 |
| 英文关键词 Qinghai-Tibet Plateau headwaters of the Yangtze River precipitation stable isotopes moisture sources |
| 作者 | 单位 | E-mail | | 汪少勇 | 中国科学院西北生态环境资源研究院, 冰冻圈科学国家重点实验室, 兰州 730000
中国科学院西北生态环境资源研究院, 内陆河流域生态水文重点实验室, 兰州 730000
中国科学院大学, 北京 100049 | wangshaoyong17@mails.ucas.ac.cn | | 王巧丽 | 长江水利委员会水文局, 武汉 430010 | | | 吴锦奎 | 中国科学院西北生态环境资源研究院, 冰冻圈科学国家重点实验室, 兰州 730000
中国科学院西北生态环境资源研究院, 内陆河流域生态水文重点实验室, 兰州 730000 | | | 何晓波 | 中国科学院西北生态环境资源研究院, 冰冻圈科学国家重点实验室, 兰州 730000
中国科学院西北生态环境资源研究院, 内陆河流域生态水文重点实验室, 兰州 730000 | hxb@lzb.ac.cn | | 丁永建 | 中国科学院西北生态环境资源研究院, 内陆河流域生态水文重点实验室, 兰州 730000
中国科学院大学, 北京 100049 | | | 王利辉 | 中国科学院西北生态环境资源研究院, 冰冻圈科学国家重点实验室, 兰州 730000
中国科学院西北生态环境资源研究院, 内陆河流域生态水文重点实验室, 兰州 730000
中国科学院大学, 北京 100049 | | | 胡召富 | 中国科学院西北生态环境资源研究院, 冰冻圈科学国家重点实验室, 兰州 730000
中国科学院大学, 北京 100049 | |
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| 中文摘要 |
| 基于长江源区冬克玛底流域2014年5~10月连续采集的73个降水同位素数据，结合相关气象资料，分析了降水中δD、δ18O及氘盈余（d-excess）变化特征，讨论了δ18O与气温、降水量的关系，利用HYSPLIT模型追踪流域降水的水汽来源并估算不同水汽来源对降水量的贡献比例.结果表明：研究区降水中δ18O和δD变化范围分别为-26.5‰~1.9‰和-195.2‰~34.0‰，且δ18O和δD值随时间变化波动较大，与不同来源水汽输送有直接的关系；区域降水线的斜率和截距均大于全球大气降水线，与青藏高原北侧地区的降水线相近；不同降水类型中的δ18O和δD的关系差异显著，主要与水汽来源和形成降水时的气象条件有关；由于受局地蒸发水汽及水汽输送过程影响，流域大气降水d-excess值整体上相对偏大；研究区的降水同位素存在显著的降水量效应，但不存在温度效应，表明降水量对大气降水中稳定同位素含量的控制作用更强；水汽来源轨迹表明，研究区大气降水水汽来源主要有西南季风携带的海洋性水汽、局地蒸发水汽及西风输送水汽，对降水量的贡献比例分别为43%、36%和21%.该研究结果有助于进一步了解长江源头区冬克玛底流域的大气环流特征及水循环过程. |
| 英文摘要 |
| Based on the stable isotopes of 73 precipitation samples continuously collected from May to October 2014 and related meteorological statistics in the Dongkemaldi Basin, the characteristics of δD, δ18O, and d-excess of precipitation, as well as the correlations between δ18O and the rainfall amount and air temperature were analyzed. The moisture sources were tracked by the HYSPLIT model to further estimate the contribution of different water vapor sources to the rainfall amount. The results showed that the range of δ18O and δD values varied from -26.5‰ to 1.9‰ and -195.2‰ to 34.0‰, respectively; meanwhile, the δ18O and δD values in precipitation fluctuated greatly with time in response to water vapor transport from different moisture sources of the Qinghai-Tibet Plateau. The slope and intercept of the Local Meteoric Water Line (LMWL) were both higher than those of the Global Meteoric Water Line (GMWL) and close to the LMWL in the northern area of the Qinghai-Tibet Plateau. The relationship between δ18O and δD in different precipitation types showed significant differences, which were mainly related to the source of water vapor and meteorological conditions during the process of precipitation formation. Because of the influence of local evaporation and the transport process of water vapor, the d-excess values of atmospheric precipitation were relatively large; the δ18O in precipitation had a significant amount effect, but had no temperature effect, thus indicating that the rainfall amount was more effective in controlling the stable isotope content of atmospheric precipitation than temperature. The modeled trajectory of vapor sources showed that water vapor of precipitation was mainly derived from the marine vapor carried by the southwest monsoon, local moisture, and the westerly water vapor, and their contributions to the rainfall amount were 43%, 36%, and 21%, respectively. The results of this study can contribute to further understanding of the atmospheric circulation characteristics and water cycle process of the Dongkemadi basin in the headwaters of the Yangtze River. |
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