Moisture sources and climate evolution during the last 30 kyr in northeastern Tibetan Plateau: Insights from groundwater isotopes (2H, 18O, 3H and 14C) and water vapour trajectories modeling

Abstract

Understanding the past hydrological cycle and climate change may contribute to the sustainable utilization of water resources. Here we combined groundwater stable isotopes (2H and 18O), age dating (3H and 14C) and water vapour transport trajectories modeling to reveal the moisture source and climate evolution over the last 30 kyr in southeastern Qaidam Basin, northeast Tibetan Plateau. The compositions of δD and δ18O indicated that the groundwater was mainly recharged by precipitation and snowmelt water from the East Kunlun Mountains in the south. The groundwater stable isotopes exhibited a depleted trend from west to east across the four catchments of the basin which seemed not to alter since the late stage of the Late Pleistocene. A combination of the deuterium excess (d-excess) of groundwater and present-day moisture source modeling revealed that the moisture source had been dominated by the Westerlies without obvious impact of the summer monsoon since the last 30 kyr. The enriched δD and δ18O of groundwater during the Holocene suggested a warmer climate than the late stage of the Late Pleistocene, which seemed not to be accompanied by moisture source variations. The results of this study could be helpful for both climate change and water resource research in this region or even, over the entire Tibetan Plateau.