Saline groundwater formation in an extremely arid inland basin in northwestern China

• Published in: Hydrogeology journal Vol. 33; no. 3; pp. 739 - 754
• Main Authors: Luo, Mingming, Peng, Xiangyu, Zhao, Zehao, Qin, Dongshi, Pan, Hongjie
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2025; Springer Nature B.V
• Subjects: Aquatic Pollution; Aquifers; Arid regions; Arid zones; Basins; Carbon 14; Cation exchange; Cation exchanging; Cations; China; Circulation; Confined aquifers; Confined groundwater; Cretaceous; Cretaceous period; Dissolution; Dissolved solids; Dissolving; Earth and Environmental Science; Earth Sciences; Evaporation; Exploration; Geology; Geophysics/Geodesy; Glacial periods; Glaciation; Glaciology; Groundwater; Groundwater resources; Groundwater salinity; Gullies; Hydrogeochemistry; Hydrogeology; Hydrology/Water Resources; Ice ages; Infiltration; Isotopes; Mountains; Ravines; Recharge; Resource exploration; Saline groundwater; Salinity; Salinity effects; Salinization; Total dissolved solids; Unconfined aquifers; Waste Water Technology; Water Management; Water Pollution Control; Water Quality/Water Pollution; Water resources; water salinity; China; Groundwater circulation; Hydrochemical evolution; Arid region; China; Groundwater age
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-025-02894-3

In extremely arid inland regions, groundwater resource exploration and management are challenged by limited recharge rates and processes that lead to saline groundwater formation. This study employs a multifaceted approach incorporating hydrogeochemical methods, stable water isotopes, and radioactive 14 C isotopes to investigate groundwater origins, residence times, hydrogeochemical evolution, and circulation in the Beishan Mountains and surrounding basins, northwestern China. The results indicate that the average total dissolved solids (TDS) in confined and unconfined groundwaters are 10.4 and 7.2 g/l, respectively. The groundwater in this region is subject to intense evaporation, followed by dissolution and cation exchange, resulting in high groundwater salinity. Confined groundwaters in the Cretaceous basins have ages ranging from ~4900 to 20,800 years, whereas the majority of unconfined groundwaters are of modern ages. The confined groundwaters in the Cretaceous basins feature recharge contributions dating back to the Last Glacial Period, characterized by lower salinity and negative δ 18 O values, while the higher TDS and δ 18 O content of modern recharge are affected by the evaporation during the infiltration process. In such arid environments, two distinct regions with fresh groundwater have been identified: one in unconfined aquifers with modern groundwater ages present within gullies, and the other in confined aquifers along the perimeter of the basin, where recharge experiences less evaporation. This research has elucidated the fundamental principles governing groundwater circulation in the region and the mechanisms governing groundwater salinity, providing invaluable insights for fresh groundwater resource exploration in this exceptionally arid region.