长江流域降水中氢氧同位素特征及水汽来源

Analysis of Stable Isotope Characteristics and Water Vapor Origins in Atmospheric Precipitation in the Yangtze River Basin

利用全球降水同位素观测网(GNIP)所提供的数据,研究了位于长江流域的南京、武汉、成都、昆明4个站点大气降水δ^(18)O及其相关要素的时空分布特征。对长江流域4站点大气降水中的δ^(18)O与气温、降水量、在不同时间尺度下的相关关系进行了分析与研究,提出长江流域的大气降水线方程并与全球及我国大气降水线相比较。结果表明,4站点δ^(18)O与δD年平均值波动较小,而多年月平均值波动较大,其中昆明波动最大。季节尺度下,长江流域大气降水中δ^(18)O在干季具有显著的温度效应,在湿季具有降水量效应;年尺度下,长江流域具有降水量效应。与全球大气降水线相比,长江流域大气降水线的斜率与截距都要偏小,尤其是截距偏低很多。利用HYSPLIT模型对南京与昆明站点1991年夏季水汽路径进行聚类分析,其分析结果与大气降水线及氘盈余分析结果一致,即站点存在不同水汽来源。

Based on the data provided by the Global Network of Isotopes in Precipitation （GNIP）, this paper studies spatial and temporal characteristics of δ18O regarding four cities in the Yangtze River basin including Nanjing, Wuhan, Kunming and Chengdu, where stations of GNIP were sited; besides, this paper analyzes the relation of δ18O with temperature and rainfall in different time scales. The study suggests that monthly average values of δ18O and 8D fluctuated in the four cities, of which Kunming fluctuates most, while the annual average values ofδ18O and δDonly slightly change; seasonally, δ18O in precipitation is affected by temperature during dry season and affected by rainfall amount during wet season; and in the year scales, δ18O in precipitation is remarkably affected by rainfall amount. In comparison with the global meteoric water line, the meteoric water line in the Yangtze River basin features smaller slope and intercept, especially the intercept. The trajectory of air mass has been cluster-analyzed using the model of HYSPLIT, indicating that the four cities have different water vapor origin.