Hydrogeochemical characterization, multi-exposure deterministic and probabilistic health hazard evaluation in groundwater in parts of Northern India

Abstract

This work attempts to identify the latent factors controlling the hydrogeochemistry and assess the groundwater quality and associated health risks in the intermontane valley of Nalagarh in the sub-Himalayan zone in northern India. Analytical results of 64 groundwater samples, 32 each collected during pre monsoon and post monsoon seasons show contrasting results for their major chemical constituents. During pre monsoon period, only 3% of the samples exceed their permissible limits for pH, EC, TH and Mg2+, while during post monsoon period, different parameters, such as TH, Mg2+ and K+, exceed their limits by 9, 16, and 3%, respectively. Gibbs and Piper diagrams reveal that groundwater chemistry is mainly controlled by water-sediment (alluvial) interaction. Geochemical signatures and saturation index (SI) further indicate that the weathering and dissolution of silicate, calcite and dolomite minerals mainly contributed to dominance of Ca2+, Mg2+ and HCO3 - ions in the aquifers. Monte Carlo simulation ascertains non-carcinogenic health risks due to NO3 − and F− in different sub-population groups. Deterministic and probabilistic estimates of these parameters via ingestion and dermal routes confirm their percentage hazard toxicity in the order infants (58.38; 39.62%) >children (15.62; 15.85%) >teens (6.25; 2.73%) >adults (6.25; 1.90%) for pre monsoon. The hazard toxicity for deterministic study implies only on infants (9.38%), whereas, the probabilistic simulation extracted the health risk on infants (6.57%), and children (0.58%) during post monsoon. Minor populations with their lower body weights are more vulnerable to groundwater pollution due to greater consumption of liquid diet. Therefore, treated groundwater is strongly recommended to mitigate health morbidities linked with the non-cancerous risks.