黄河小浪底库区降水δD和δ18O季节变化特征及水汽来源

2011—2014年4—10月在位于我国东部季风区的黄河小浪底库区收集降水样品及相应气象资料，分析该地区大气降水的δ_D和δ¹⁸O季节变化规律及影响因素，建立不同季节大气降水线，揭示该地区不同季节水汽来源差异.结果表明： 降水的δ_D和δ¹⁸O值变化范围较大，具有明显的季节变化，春季降水的δ_D和δ¹⁸O值较高，夏季次之，秋季最低.4—10月及秋季降水δ_D和δ¹⁸O与降水量存在负相关关系，4—10月降水δ_D与温度呈负相关关系，而季节性降水同位素与温度的相关性不显著.夏季大气水线斜率及降水过量氘（d值）较小，而秋季最大.利用HYSPLIT气团轨迹模型得出夏季水汽主要来自东南及西南海洋性季风输送，春秋季节降水受大陆和海洋性季风共同影响.

Seasonal characteristics of δD and δ18O in precipitation and its water vapor sources in the Xiaolangdi Reservoir area of Yellow River,China.

The seasonal characteristics of δ_D and δ¹⁸O in precipitation and the influence factors were studied in the Xiaolangdi Reservoir area at the eastern monsoon region of China. The precipitation samples and the corresponding meteorological data were collected between April and October from the year 2011 to 2014. The local meteoric water lines (LMWL) of different seasons were established, and the water vapor sources in different seasons were investigated. The results showed that the δ_D and δ¹⁸O in precipitation exhibited an extremely wide range and a distinct seasonal variation, and they were enriched in the spring, and depleted in the fall. The δ_D and δ¹⁸O values showed negative correlations with the amount of precipitation from April to October and the fall, respectively. The δ_D values and the mean air temperature showed a negative correlation from April to October, but showed no correlation in seasonal precipitation. Both the slopes of LMWL and excess deuterium (d values) of precipitation were the smallest in the summer, and the largest in the fall. The results of air mass back trajectories of seasonal precipitation using the HYSPLIT model indicated a dominant effect of southeast and southwest maritime monsoon air masses in the summer and the coinfluence of continental and oceanic monsoons air masses in the spring and fall in the study area．