Determination of uranium concentration in ground water samples of Northern Greece

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