Stable isotope variations in the ground ice of Beiluhe Basin on the Qinghai-Tibet Plateau

Ground ice is extensive in the permafrost regions of the Qinghai-Tibet Plateau. It is useful for regulating water resources in Plateau regions, and affects the ecological water environment in permafrost areas. This research investigated the isotope characteristics of ground ice on the Qinghai-Tibet Plateau. In this work, 73 samples of ground ice from 4 boreholes were collected to analyze and compare stable isotopes with precipitation and river water. The results show that isotope composition of ground ice varied in narrow ranges, ranging from −13.16‰ to −9.08‰ for δ18O and from −103.61‰ to −69.92‰ for δD. The isotope composition of subsurface ground ice is slightly more positive than that of deep-layers due to the fractionation of freezing. Based on the recharge relationships among ground ice, precipitation, and river water, subsurface ground ice is partly recharged by precipitation and river water. However, the isotope variations of deep-layer ground ice may be the result of isotope fractionation under different climate conditions.