Hydraulic connection affects uranium distribution in the Gas Hure salt lake, Qaidam Basin, China

The widespread hydraulic connection is necessary for the formation of a salt lake. However, only limited studies have ever been carried out to investigate the influence of the hydraulic connection on the distribution of elements around certain salt lake. In this study, a total of 66 water samples (including river water, stream water, spring water, brine, intercrystalline brine, well water, and drilling brine) were collected around the Gas Hure salt lake (GSKLH) to investigate the relationship between hydraulic connection and uranium (U) distribution via hydrochemistry and isotope (²³⁴U/²³⁸U, δ¹¹B) techniques. The results suggested that the GSKLH was recharged by water from the Kulamulekesay and Atetikan rivers, groundwater (borehole brine and some intercrystalline brine), and deep fluid (some intercrystalline brine), with each contributing 44.03%, 14.95%, and 41.02% of total recharge, respectively. The U-bearing rock was dominated mainly by silicates, carbonates, and evaporites in the high mountain area (region 1), overflow area (region 2), and plain area (region 3) of the GSKLH, respectively. In the GSKLH, the U distribution was strongly correlated with hydraulic connection and the U concentration was influenced by both groundwater flow system and flow velocity (represented by the γCl^-/γCa²⁺ ratio). Thus, U was enriched under the conditions of regional groundwater flow system and slow velocity in the GSKLH.