Comprehensive evaluation of hydro-chemical processes, suitability, health risks, and sources of groundwater contamination using compositional data analysis, Nizampur basin, Pakistan

This study aimed to evaluate the level of contamination, health risks, hydro-chemical processes, and sources of contaminants in the groundwater of the Nizampur basin, northwestern Pakistan. Forty-eight (n = 48) groundwater samples from predefined locations were collected and analyzed using the standard procedure for a total of 13 parameters. Statistical techniques in the compositional data analysis perspective were used for the identification of sources. The results showed that TDS, Turbidity, SO4, and NO3 concentrations surpassed the limits in 44, 29, 25, and 48% of samples, respectively. The nitrate pollution index indicated that 48% of the samples were contaminated with nitrates, while the composite index PIG showed that only 22% of the samples indicated low pollution. A close association between the land use/land cover of the study area and NO3 contamination was observed. In general, the groundwater of the region could be categorized as fresh-very hard water (87.5%), the major hydro-chemical facies were, Ca–Mg–HCO3, followed by mixed Ca–Mg–Cl and Ca–Cl facies. The Van Wirdum diagram showed that groundwater was mainly influenced by rock weathering and profound human impact. Similarly, it was assessed using chloro-alkaline indices that reverse ion exchange is a governing hydro-chemical process. NO3 concentrations in the area have the potential to cause non-cancer ailments in 75% and 47% of the samples in children and adults respectively. Based on the assessments made using the compositional data analysis it was inferred that NO3, SO4, Cl, and Turbidity originated from human sources, while the rest of the parameters have natural/geogenic sources.