Radiological aspects of some Egyptian thermo-mineral springs

Abstract

In Egypt, nineteen water springs with temperatures exceeding 35 °C, which can be considered thermal waters, were reported. The radiological aspects of thermal water in three northern regions of Egypt (Gulf of Suez, Cairo, and Bahariya Oasis) were investigated. The activity concentrations of natural radionuclides of ²²⁶Ra, ⁴⁰K, total uranium and ²¹⁰Pb (²¹⁰Po) in water samples were determined using gamma spectrometry, laser fluorimetry and alpha spectrometry after chemical separation, respectively. The highest concentrations are detected in two locations, namely Sudr and Hammam Faroun springs, which are the hottest waters in Egypt (89 and 72 °C respectively). It seems that the presence of ²²⁶Ra is correlated to the water mineralization and the depth and the temperature of the reservoir's base. Also, these results seem evidence of uranium accumulation at depth in the mother bedrock and/or uranium immobilization due to uranium reduction to the immobile 4+-oxidation state in the reservoir base. The average activity concentrations of ⁴⁰K are dependent on the water's origin, i.e. meteoric water mixed with sea water (Gulf of Suez springs) and meteoric water (Bahariya Oasis wells). There is no prescribed dose limit for short term and temporary exposure to thermal water. Workers at the thermal springs should be regularly monitored because of their continuous exposure to enhanced radiation levels over a long period of time. The hydrochemical characteristics, environmental isotopes aspects and water origin are briefly discussed based on published data.