Hydrochemical behaviour of dissolved uranium in selected groundwaters of the Kłodzko Valley (SW Poland) and its application possibilities as an environmental tracer

Abstract

Waters from the Kłodzko Valley containing pharmacodynamics therapeutic agents are used for drinking and for balneotherapeutical purposes. These medicinal, highly mineralized waters are mostly of deep circulation. Moreover, outflowing water contain admixture of shallow circulation water of contemporary infiltration which negatively effects medicinal water quality. Due to the complicated pathways of groundwater circulation, the authors used uranium as an environmental indicator to gain deeper insight into the factors affecting the quality of exploited medicinal water and groundwater origin. The authors collected samples from 26 groundwater intakes from 3 Spas and from one mineral water bottling plant for analysis of ^234,238U and ²³⁴U/²³⁸U activity ratios using α-spectrometry technique. Uranium was applied as a dilution tracer of medicinal mineral groundwater by shallow circulation low-mineralized water. The results of ²³⁴U/²³⁸U activity ratios in particular water intakes collected in different years were equal in the range of uncertainties although the uranium concentrations varied. The stability ²³⁴U/²³⁸U activity ratio parameter is a consequence of dilution of medicinal water by shallow circulation water of present infiltration with a very small amount or without uranium. Apart from simple water dilution, waters of deep circulation mixed with low mineralized shallow circulation water may also contain an admixture of third deeper circulation component with different both U content and ²³⁴U/²³⁸U ratio. In that case ²³⁴U/²³⁸U ratio may be applied as a hydrogeochemical tracer.

Keywords: (234)U/(238)U activity Ratio; (234,238)U concentrations; Environmental tracer; Groundwater dilution; Uranium hydrochemistry.