Determination of uranium concentration in ground water samples of Northern Greece

¹ Aristotle University of Thessaloniki, Physics Department, Nuclear Physics & Elementary Particle Physics Division, 54124, Thessaloniki Greece
² Department of Chemistry, University of Cyprus - CY-1678, Nicosia Cyprus

^* E-mail: anta@physics.auth.gr

Abstract

The activity concentration of ²³⁸U and ²³⁴U has been determined in groundwater samples of hot springs and deep wells from the region of Northern Greece. The analysis was performed by alpha spectroscopy after pre-concentration and separation of uranium by cation exchange (Chelex 100 resin) and finally its electro-deposition on stainless steel discs. The uranium concentration in deep wells and springs varies strongly between 0.15 and 7.66 μg l⁻¹. Generally the springs present higher uranium concentration than the deep wells, except of the Apol-lonia spring, which has shown the lowest value of 0.15 mg l⁻¹. ²³⁸U and ²³⁴U activity concentration ranged between 1.8–95.3 mBq l⁻¹ and 1.7–160.1 mBq l⁻¹, respectively. The obtained isotopic ratio ²³⁴U/²³⁸U varies between 0.95 and 1.74 which means that the two isotopes are not in radioactive equilibrium. The highest ²³⁴U/²³⁸U activity ratio values correspond to the Langada springs, indicating most probably old-type waters. On the other hand, ground waters from wells with relatively low uranium activity concentration and low ²³⁴U/²³⁸U isotopic ratios, point to the presence of younger waters with a stronger contribution of a local recharge component to the groundwater.