Applications of geochemical and multivariate statistical approaches for the evaluation of groundwater quality and human health risks in a semi-arid region of eastern Maharashtra, India

Abstract

A qualitative approach, including geochemical and multivariate statistical approaches, is applied to evaluate the groundwater quality and human health risk, based on analytical data of 72 samples collected from a semi-arid region of eastern Maharashtra, India. The shifting of hydrochemical type from Ca²⁺–Na⁺–${\rm H}{\text{C}}{\rm O}_{3}^{ - }$ to Na⁺–Ca²⁺–Cl⁻ type was observed along different flow paths. The main controlling processes observed from the chemical characterisation of the groundwater are water–rock interactions, dedolomitisation and reverse ion exchange. Simulation analysis (mass transfer) exposes the dissolution of dolomite, gypsum, halite, k-feldspar and CO₂ down the simulated pathways. Around 77% of the total variance was observed from the first three principal component analyses. The high positive loadings of EC, TDS, Na⁺, K⁺, Ca²⁺, Cl⁻, ${\text{NO}}_{3}^{ - }$ and ${\text{SO}}_{4}^{2 - }$ of PC1 revealed silicate weathering and reverse ion exchange followed by human activities as the contamination sources. The sources identified for high positive loadings on ${\rm H}{\text{C}}{\rm O}_{3}^{ - }$ and ${\text{SO}}_{4}^{2 - }$ of PC2 are soil CO₂ and human activities. The high loadings of pH and F⁻ in PC3 revealed fluorite dissolution and calcite precipitation. The human health risk calculated for ${\text{NO}}_{3}^{ - }$ revealed that 58% and 44% of the total groundwater samples surpassed the tolerance limit for non-carcinogenic risk of 1.0 in children and adults. The human health risk assessment for fluoride showed high hazard index values in 40% and 23% of the total groundwater samples for children and adults, respectively. The study suggests some management measures for protection of groundwater resources.