Geochemical variations in uranium and fluoride enriched saline groundwater around a semi-arid region of SW Punjab, India

Abstract

Scarcity of fresh surface water increases dependency on groundwater for agriculture and domestic consumption which itself is unsafe in many instances by excess salinity, fertilizer inputs and heavy metals. The present study examined groundwater geochemistry up to 460 ft depth around a semi-arid region of Punjab, India where fluorosis, cancer and poor crop yield are serious concerns. Groundwater from bore wells and tube wells demonstrate neutral to slight alkaline (pH 7.1–8.4) Na–HCO3 and Na–Cl water types with excess salinity (up to 9500 mg L−1). Sodium and HCO3−constitute the predominant ions in the order Na+>Mg2+≈Ca2+>K+>Si4+>Fe(T)>Al3+ and HCO3− > Cl− > SO42− > NO3− ≈ CO32− > PO43− > F−, whereas trace metal contents are insignificant except U that contaminates >83% groundwater (up to 283 μg L−1). Both dental and skeletal fluorosis is common in the region. Groundwater up to 250 ft depth contains relatively greater cations, anions, salinity, and trace metals, in general, implying both geogenic and anthropogenic contributions. The southern part of the district is severely contaminated, especially with U (up to ∼283 μg L−1) and salinity (up to 9500 mg L−1) witnessing surface salt deposits widely. The sodium absorption ratio (0.4–36.7), residual sodium carbonate (-49-97) and %Na (17–94) data represents most of the shallow and intermediate depth groundwater is unsafe for irrigation purposes with an evaporite and silicate weathering dominance control where cation exchange process predominates over reverse ion exchange at all depths. Poor productivity, excess salinity, agricultural inputs of NO3−, PO43−, F− and U along alluvial plane groundwater of dry arid climatic terrains is a global implication from this research.