Hydrogeochemical assessment of carcinogenic and non-carcinogenic health risks of potentially toxic elements in aquifers of the Hindukush ranges, Pakistan: insights from groundwater pollution indexing, GIS-based, and multivariate statistical approaches

Abstract

Globally, potentially toxic elements (PTEs) and bacterial contamination pose health hazards, persistency, and genotoxicity in the groundwater aquifer. This study evaluates PTE concentration, carcinogenic and noncarcinogenic health hazards, groundwater quality indexing (GWQI-model), source provenance, and fate distribution in the groundwater of Hindukush ranges, Pakistan. The new estimates of USEPA equations record new research dimensions for carcinogenic and noncarcinogenic hazards. The principal component analysis (PCA), mineral phases, and spatial distribution determine groundwater contamination and its impacts. The average concentrations of PTEs, viz., Cd, Cu, Co, Fe, Pb, and Zn, were 0.06, 0.27, 0.07, 0.55, 0.05, and 0.19 mg/L, and E. coli, F. coli, and P. coli were 27.5, 24.0, and 19.0 CFU/100 ml. Moreover, the average values of basic minerals, viz., anhydrite, aragonite, calcite, dolomite, gypsum, halite, and hydroxyl apatite, were 0.4, 2.4, 2.6, 5.1, 0.6, and - 4.0, 11.2, and PTE minerals like monteponite, tenorite, cuprite, cuprous ferrite, cupric ferrite, ferrihydrite, goethite, hematite, lepidocrocite, maghemite, magnetite, massicot, minium, litharge, plattnerite, and zincite were - 5.5, 2.23, 4.65, 18.56, 20.0, 4.84, 7.54, 17.46, 6.66, 9.67, 22.72, - 3.36, 22.9, 3.16, - 18.0, and 1.46. The groundwater showed carcinogenic and non-carcinogenic health hazards for children and adults. The GWQI-model showed that 58.3% of samples revealed worse water quality. PCA revealed rock weathering, mineral dissolution, water-rock interaction, and industrial effluents as the dominant factors influencing groundwater chemistry. Carbonate weathering and ion exchange play vital roles in altering CaHCO₃ type to NaHCO₃ water. In this study, E. coli, F. coli, P. coli, EC, turbidity, TSS, PO₄^3─, Na⁺, Mg⁺², Ca⁺², Cd, Co, Fe, and Pb have exceeded the World Health Organization (WHO) guidelines. The carcinogenic and non-carcinogenic impacts of PTEs and bacterial contamination declared that the groundwater is unfit for drinking and domestic purposes.

Keywords: Groundwater quality indexing; Health risk assessment model; Hindukush ranges; Hydrogeochemistry; Mineral phases; Pakistan.