Uranium hydrogeochemical study in Ayrakan and Cheshmeh Shotori areas with emphesis on complexing agents and uranium minerals saturation index

Uranium becomes soluble and mobile under oxidizing conditions in aqueous environment, and presence of complexing agents with uranium increase this mobility. Existence of such conditions in groundwaters of Ayrakan and Cheshmeh Shotori areas has led to oxidation, solubility and mobility of uranium minerals. Hydrogeochemical study of uranium in the study areas reveals the presence of bicarbonate ion, as the complexing agent with uranium (UO2 (CO3)22-) and icreasing factor of uranium mobility in groundwaters. Calculating the uranium mineral’s saturation index also indicates the super saturation of water samples in pitchblende. The positive saturation index of pitchblende expresses the proper water flow rate to steady-state equilibrium with probable uranium mineralization in depth and indicates that the permeability of groundwaters by porous flow has provided the enough time for their contact with hidden uranium mineralization (uranium ore deposit). As a result of this contact and because of the presence of carbonate complexes, solubility and mobility of uranium has increased. Hydrogeochemical studies, high activity of water and soil samples and all the above evidences indicate the possibility of existence of hidden uranium mineralization in depth and the distance between Ayrakan and the Cheshmeh Shotori areas.