Contamination zoning and health risk assessment of trace elements in groundwater through geostatistical modelling

Trace elements (TEs) concentration in groundwater is a key factor for health risk assessment (HRA). To achieve high level of accuracy in HRA, the present study performed Monte Carlo simulations, sensitivity analysis and uncertainty analysis to a total of 184 (N = 184) groundwater samples, collected during December 2016 from Birbhum district. TEs in samples were detected by anodic stripping voltammetry (ASV). The mean concentration of TEs were found as Fe (855.88 μg/L)> Zn (204.0 μg/L)> Cu(84.9 μg/L)> Ni(47.31 μg/L)> Pb(14.43 μg/L)> Co(10.58 μg/L)> Cd (7.88 μg/L). It indicated serious contamination by Fe, Cd. Pb and Ni according BIS, 2012. Pollution indicators such as heavy metal pollution index (HPI) revealed that study area is heavily contaminated by these TEs. Incremental lifetime cancer risk (ILCR) value of TEs showed that Cd is the main offender for cancer risk. Average value of total hazard index (THI), was found to be 2.48. THI through ingestion pathways was found to be more risky than dermal contacts accounting for 88% and 12% health hazard respectively. The sensitivity analysis indicated ingestion rate, exposure time, and TEs concentration were the most influential parameters for all groundwater associated health hazards. The TEs affected areas were mapped through Empirical Bayesian Kriging geostatistical model and health risk prone zones were projected. The study demonstrated that Monte Carlo simulation and EBK can provide better accuracy in health risks prediction and spatial distribution analysis of contaminants in any geographical area. The TEs and their hazard zonation mapping with geostatistical modelling will be helpful for the policy makers and researchers to improve groundwater quality management practices.