SPATIO-TEMPORAL DISTRIBUTION OF URANIUM CONCENTRATION IN SHALLOW AQUIFERS OF ARAVALLI TERRANE (NORTH GUJARAT), INDIA

In India, rural communities mostly depend on groundwater for various purposes and hence it is essential to monitor groundwater quality. Uranium in groundwater is one of the important constituents that affect the water quality and hence health of humans. Uranium concentration above 30 ppb in drinking water may cause health issues. The study area falls under Ambaji basin of Aravalli-Delhi fold belt (ADFB) which is running 700-800 km in NE-SW direction and situated in NW India. The study was carried out for analyzing the spatio-temporal variations of uranium in shallow aquifers. The results show that the uranium concentration in groundwater ranges from 10.1 ppb to a maximum of 62.5 ppb with a mean of 30.65 ppb in the study area. It is observed that the concentration of uranium in groundwater mainly depends on the structure, degree of weathering and rock compositions in the aquifer. Structural study shows that higher uranium concentration confined along the ductile shear zones where the degree of fracturing is more compared to the brittle zones. Furthermore, the study finds that combination of different factors such as uranium-rich rocks (mainly granite) and over-exploitation of the aquifers due to irrigation activities, the groundwater table declines and in turn induces oxidation conditions that lead to uranium enrichment in groundwater.