Spatial variability and risk assessment of metals in groundwater of district Kamber-Shahdadkot, Sindh, Pakistan

The study examined the groundwater quality of agricultural based area Nasirabad, Warah and Miro Khan talukas of district Kamber-Shahdadkot. Representative 46 samples were collected commonly used for drinking purposes and analyzed for 25 different quality parameters by using standard analytical procedures. The GIS interpolation tools were used to exhibit the spatial variation of groundwater parameters, for drinking as well as irrigation in the study area. The values of EC and TDS varied from 569 to 17790 μS/cm and 364–11385 mg/L respectively. The results of anions varied HCO₃⁻ from 140 to 460, Cl⁻ 21 to 4545 and SO₄²⁻ 28 to 2050 mg/L and results of cations varied from Na⁺ 20 to 1380, K⁺ 03 to 143, Ca²⁺ 32 to 1302 and Mg²⁺ 15–728 mg/L. Results of heavy metals varied from Pb 0–44 μg/L, Co 3.9 to 63.8, Cu 0 to 3.9 to 63.8, Fe 10.1 to 335, Cr 0 to 134, Ni 0 to 152, Mn 0 to 140 and Cd 0–29.4 μg/L. The fluoride value of 80.44% samples were above the allowable limits for drinking. The water quality index (WQI) results showed that 70% samples were in poor to unfit water categories. The contaminated index showed 47.82% samples with higher Cd values than 3. The chronic daily intake (CDI) and hazards quotient indices (HQ) were also calculated and HQ did not indicate possible hazourds effects on human health. The samples were examined for principal component analysis, Gibb's diagrams, contour diagrams, scatter diagrams, correlation matrix, Piper diagrams and cluster analysis. The Piper plots showed Na⁺-Cl⁻, Ca²⁺-Mg²⁺-HCO₃⁻ and Ca²⁺-Mg²⁺-Cl⁻ species and Gibbs diagrams showed rock and evaporation dominancy. The scatter plots were used to know the hydrochemistry of the area like ion exchange and weathering processes. The quality of water was examined for agriculture, based on chloride bicarbonate ratio, sodium percentage, salinity hazard, Kelly's index, chloro alkaline indices I, chloride-sulphate ratio, residual sodium carbonate, sodium adsorption ratio and permeability index. The results showed that 44–80% samples were fit for irrigation purposes depending upon the requirement of agriculture.