Hydrogeochemical characterization and quality assessment of groundwater resource in Savar - an industrialized zone of Bangladesh.

Abstract

Savar Upazila in the Dhaka District is a rapidly expanding city with a diverse range of industries and agricultural activities. This expansion poses environmental challenges including the threat to groundwater contamination. Based on these considerations, the objective of this research is to carry out ashallowgroundwater hydrogeochemical characterization and an assessment of the suitablity of the groundwaterfor drinking and irrigational purposes using a geochemical approach, multivariate statistical techniques, and some indices ofgroundwater quality. Thehydrogeochemical analyses of 42 groundwater samples from shallow depths (18 - 76m) showed that the order of concentrations of cations, anions, and metals was Ca2+ > Na+ > Mg2+ > K+, HCO3- > Cl- > SO42- > NO3-, and Cr > As > Pb > Mn > Fe, respectively. Weathering of silicates was found to be the most significant hydrogeochemical process governing the chemistry of groundwater. Cation exchange also plays a significant role in the evolution of thegroundwater chemistry. Principal component analysis and hierarchical cluster analysis suggested that anthropogenic activities are influencing groundwater quality. A drinkingwater quality index map showed that about 91% of the groundwater samples were in the excellent category and suitable for human consumption, with only a few samples exceeding the standards of theWHO and Bangladesh for concentrations ofCa2+, Mg2+, HCO3-, Fe, Mn, and As. An analysis of irrigation quality parameters found that most of the groundwater samples were eitherexcellent or good for agricultural uses, except for one samplein the Tetuljhora Union that was unsuitable based on residual sodium carbonate. This finding may be useful to local governments in understanding the current status of groundwater quality, tracking potential threats of contamination, and initiating appropriate measures for long-term groundwater resource management.