Articles | Volume 21, issue 9
Hydrol. Earth Syst. Sci., 21, 4419–4431, 2017
Hydrol. Earth Syst. Sci., 21, 4419–4431, 2017

Research article 07 Sep 2017

Research article | 07 Sep 2017

Origin of water in the Badain Jaran Desert, China: new insight from isotopes

Xiujie Wu1,2,3, Xu-Sheng Wang1, Yang Wang2,3,4, and Bill X. Hu1,2,4 Xiujie Wu et al.
  • 1School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, P. R. China
  • 2Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, USA
  • 3High National Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
  • 4Institute of Groundwater and Earth Sciences, The Jinan University, Guangzhou, Guangdong Province, 510632, P. R. China

Abstract. To better understand the origin of water in the Badain Jaran Desert, China, water samples were collected from lakes, a spring and local unconfined aquifer for analyses of radiocarbon (14C), tritium (3H), stable hydrogen and oxygen isotope ratios (δ2H – δ18O), and d-excess values ( = δ2H – 8δ18O). A series of evaporation experiments were also conducted in the desert to examine how the isotopic signature of water may change during evaporation and infiltration under local environmental conditions. The results show that the lakes in the southeastern sand dune area are fed by groundwater discharging into the lakes and that local groundwater, on the other hand, is derived primarily from modern meteoric precipitation in the region. Although dissolved inorganic carbon (DIC) in groundwater yielded very old radiocarbon ages, the presence of detectable amounts of tritium in groundwater samples, together with their δ2H, δ18O and d-excess characteristics, strongly suggests that the old radiocarbon ages of DIC do not represent the residence time of water in the aquifer but are the result of addition of old DIC derived from dissolution of ancient carbonates in the aquifer. The data do not support the hypothesis that the water in the Badain Jaran Desert was sourced in remote mountains on the northern Tibetan Plateau. This study also finds no support for the hypothesis that present-day water resources in the desert were recharged by the precipitation that fell in the past during the early Holocene when the climate was much wetter than today. Instead, this study shows that both groundwater and lake water originated from meteoric precipitation in the region including mountainous areas adjacent to the desert under the modern climatic condition.

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Short summary
It is critical to identify the origins of water in arid and semiarid regions for management and protection of the water resources. The D, 18O, 3H and 14C in water samples from the Badain Jaran Desert, China, were analyzed. The results show that groundwater supplies the lakes and originates from local precipitation and adjacent mountains. Negative d-excess values of water in the area were the result of evaporation. The 14C ages do not represent the residence time of local groundwater.