Chemical and isotopic compositions of groundwaters in the Badain Jaran Desert, Northern China

Despite its extreme aridity the Badain Jaran Desert is rich in groundwater. In the southeastern part of this desert it is characterized by coexistence of high megadunes and a great number of lakes. Deuterium and oxygen 18 isotope compositions as well as hydrochemistry of groundwater, lake water, soil water and river water were investigated in detail to gain an insight into their relationships and the origin of the groundwater. The results show that the groundwater and the lake water are genetically related, but unrelated to local precipitation and the leakage of Heine River at the northern slope of the Qilian mountain. dD and d18O values of deep soil water (deeper than 40 cm) and groundwater plot on the same evaporation line E11, which shows that they have the same recharge source. The point of intersection between E11 and LMWL suggests that the groundwater originates from a water resource, which has a weighted mean value that is lighter by some 6 per mil d18O than local precipitation in Badain Jaran Desert. 3H data of water samples show that the groundwater in the Badain Jaran Desert originates from water recharged after the nuclear test. The deep fault zone underground maybe a water circulation channel based on helium analysis of groundwater. The result has guiding significance to rational exploitation and utilization of the local groundwater.