Chloride and the Environmental Isotopes as the Indicators of the Groundwater Recharge in the Gobi Desert, Northwest China

Authors

J. Z. Ma, Lanzhou University
Z. Ding, Lanzhou University
John B. Gates, University of Nebraska-LincolnFollow
Y. Su, Cold and Arid Regions Environmental and Engineering Research Institute

Date of this Version

2008

Comments

Published in Environmental Geology 55 (2008), pp.1407-1419; doi: 10.1007/s00254-007-1091-1. Copyright © 2007 Springer-Verlag.

Abstract

The long term recharge in Gobi Desert from Hexi Corridor to Inner Mongolia Plateau was estimated to Be 1 mm year^-1 by using the chloride mass balance method from one unsaturated zone profile, which shows that no effective modern recharge is taking place. A good rainfall database from Zhangye provides definition of the stable isotopic composition of modern rainfall. The signature of groundwater from the late Pleistocene differs markedly from that of the Holocene, shown clearly by the compositions of -10.5‰ δ¹⁸O as compared with values of -7‰ at the present day. It is apparent that the groundwaters in the Minqin Basin, Ejina Basin and feeding the lake system of the Badain Jaran are part of a regional flow network related to a wetter past climate as source of recharge. The recharge source in the past and to a limited extent in the more arid conditions of the present day included the foothills of the mountains of the Tibetan Plateau. The tritium age determinations accurate to the year are impossible and of no meaning to groundwater studies. A tritium value in the groundwater means multiple recharge ages in this region.