Comprehensive assessment of groundwater quality and health risks through probabilistic and sensitivity approaches

A comprehensive study on groundwater quality of a coastal aquifer system has been carried out to evaluate the health impacts on population, using deterministic and probabilistic approaches. This study was necessitated considering the rapid urbanisation and industrial development of this region, coupled with increasing freshwater demand. Samples from different locations are analysed for major ions, trace metals and naturally occurring radioactive elements; and their possible impact on human health is evaluated. Brown’s weighted arithmetic index, total hazard quotient (THQ), and incremental lifetime carcinogenic risk (ILCR) are employed for water quality and health risk assessment; and Morris approach is adopted for sensitivity analysis. Principal Component Analysis (PCA) is used to assess the sources of heavy and trace metals. The outcomes of this investigation indicate, groundwater needs pre-treatment for drinking, while it is usable for irrigation with no to slight restrictions. The radiation exposure due to presence of naturally occurring radioactive elements in groundwater is found to be within the limits stipulated by Atomic Energy Regulatory Board (AERB), India. The carcinogenic risk from heavy and trace metals is found to be higher than the noncarcinogenic risk. The risk estimated from probabilistic method was higher than those obtained by deterministic approach. The order of sensitivity, for carcinogenic and non-carcinogenic risks are found to be Ni > Cr> Pb > Rn, and Cr > Pb> Ni ≈ Li> Fe ≈ Zn ≈ Cu ≈ Mn respectively. PCA reveals that the heavy and trace elements are mainly derived from geogenic sources. Health risk is largely dependent on gender, age and water consumption patterns, in addition to heavy metal concentrations. Carcinogenic risk is contributed by Ni > Cr> Pb while non-carcinogenic hazards are sensitive to Cr and Pb. The statistical analysis point to geogenic sources for the presence of heavy and trace metals in groundwater. Probabilistic estimation indicated a higher possibility of carcinogenic risk than estimated from deterministic approach.