Risk identification of salts and heavy metals in water by multivariate statistical techniques and GIS based interpolation: A case study of Saeedabad, Sindh, Pakistan

Abstract

Underground water is the most common source for drinking and depends on environmental functions in the ecosystem. In Pakistan water demand is increasing and quality of water is decreasing due to contaminations of salts and heavy metals. Total of 45 water samples were collected form Taluka Saeedabad, District Matiari, Sindh and evaluated for physicochemical parameters, anions, essential and trace metals. The study was examined for multivariate statistical integrated approaches along with conventional plots of geographic mapping employed to classify hydrological study of groundwater. The geochemical modelling using GIS map of the study area were drawn for TDS, F, As and WQI to classify groundwater quality. TDS results ranged from 245 to 1926 mg/L with mean 923.45 mg/L. TDS of 17 (38%) samples exceeded WHO limit and were not fit for drinking. Higher samples concentration range for anions and cations above the permissible limits of WHO were found in the order of HCO3− >NO3− >SO42− >PO43− >Cl− and Na+ >K+ >Mg2+ >Ca2+. Toxic elements of fluoride and arsenic were in 31% and 18% samples exceeding the WHO limit. The calculated values for WQI were found in the categories good (27%), poor (49%), very poor (20%) and unfit (4%) for drinking. The hydrochemical investigation in Piper diagram indicated similar characteristics with mixed type water. Gibbs diagram indicated most samples were found in evaporation dominancy and rock weathering dominancy for cations and anions. Health risk assessments are reported in hazard quotient, chronic daily intake and contamination index. Groundwater quality for irrigation were also analyzed and moderately suitable for agriculture.