Determining the genetic origin of nitrate contamination in aquifers of Northern Gujarat, India
2014
Rina, Kumari | Dutta, P. S. | Singh, Chander Kumar | Mukherjee, Saumitra
Over the past decades, the Gujarat state of India experienced intensive agricultural and industrial activities, fertilizer consumption and abstraction of groundwater, which in turn has degraded the ground water quality. Protection of aquifers from nitrate pollution is a matter of prime concern for the planners and decision-makers. The present study assessed the spatial and temporal variation of groundwater nitrate levels in areas with different land use/land cover activities for both pre- and post-monsoon period. The pre-monsoon nitrate level (1.6–630.7 mg/L) in groundwater was observed to be higher as compared to the post-monsoon level (2.7–131.7 mg/L), possibly due to insufficient recharge and evaporation induced enrichment of agrichemical salts in groundwater. High HCO₃⁻(200–1,000 mg/L) as well as SO₄²⁻/Cl⁻(0.111–0.992) in post-monsoon period provides a favourable environment for denitrification, and lower the NO₃levels during the post-monsoon period. The K vs NO₃scatter plot suggests a common source of these ions when the concentration is <5 mg/L, the relationships between different pollutants and nitrate also suggest that fertilizers and other sources, such as, animal waste, crop residue, septic tanks and effluents from different food processing units present in the area can be attributed to higher nitrate levels in the groundwater. Appropriate agronomic practices such as application of fertilizers based on calibrated soil tests and proper irrigation with respect to crop can minimize the requirement for inorganic fertilizers, which can bring down the cost of cultivation considerably, and also protect groundwater from further degradation.
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