Hydrochemistry modelling: evaluation of groundwater quality deterioration due to anthropogenic activities in Lahore, Pakistan

Anthropogenic activities adversely affect the drinking water quality. This study examined the effect of anthropogenic activities on groundwater quality of Lahore city, Pakistan. Hydrochemistry modelling approach was applied to thirteen tube wells of the study area. Lithology profiles (borehole logs and fence diagram) indicated variable lithology in the study area. It was categorized into two types, i.e. clay dominant and sand dominant. The physico-chemical characterization of groundwater samples revealed that all parameters were found within the WHO guidelines for drinking water, except alkalinity, Cd, Cr, Ni and Pb. Piper, Stiff, Durov and Schoeller diagrams indicated the presence of bicarbonates anionic and sodium and potassium cationic systems. The abundance of cations and anions was in the order of Na > K > Ca > Mg and HCO 3 > Cl > SO 4 , respectively. In the ion exchange studies, negative chloro-alkaline indices values indicated the replacement of divalent cations with sodium. Saturation indices by PHREEQC modelling have values < 0 and Gibbs diagram indicated that groundwater tends to dissolve more minerals, leading to precipitation reactions in water. The plot of heavy metal concentrations using GIS maps specified the abundance of heavy metals in tube wells near River Ravi, likely caused by recharge of groundwater by the river which receives heavy quantities of untreated industrial effluents. Graphic Abstract