Variation characteristics of stable isotopes in different water bodies in Southwestern China monsoon area---A case study of Beibei District,Chongqing

The hydrogen and oxygen isotopes of precipitation water in Beibei District of Chongqing and water in Longtanzi reservoir in upper stream Maanxi were investigated during a hydrologic year (2014),to explore the relationship ofδD and δ1 8 O between precipitation and the reservoir water. It was found that the correlation between δD and δ1 8 O in the precipitation is extremely significant, namely,δD=8.82δ1 8 O+18.97,r=0.99,n=101,P <0.01.The slope and intercept of local meteoric water line are both greater than the global meteoric water line and China meteoric water line.The result suggested that southwest monsoon and southeast monsoon have alternative influence on local precipitation;(2)BothδD Dandδ1 8 O values in rain water exhibited significant seasonal variations,having lower values in summer and higher ones in winter;(3)Theδvalue and precipitation as well as temperature assumed negative correlation. The precipitation amount effect of the δD and δ1 8 O in the precipitation was very profound,which concealed the temperature effect;(4)The δD and δ1 8 O in reservoir had a great correlation and they fell near the global meteoric water line and local meteoric water line.In addition,the excess deuterium (d)in the reservoir wa-ter and in the precipitation showed very similar patterns.The result indicated that the precipitation recharged the reservoir.However,the variety range of theδD andδ1 8 O from reservoir was far less than precipitation. The result suggested that the reservoir was not only recharged by precipitation,but also by soil water and groundwater.