HYDRO-GEOCHEMICAL EVALUATION OF GROUNDWATER AND AQUIFER CHARACTERISTICS-A CASE STUDY FROM SADAR UPAZILA OF CHAPAINAWABGANJ DISTRICT, BANGLADESH

Concern over the effects of different chemical elements in groundwater quality and negative impact on human health is growing with the growth of population both in rural and urban areas. With this view, a hydro-geochemical investigation has been carried out in Sadar Upazila of Capainawabganj District. Through this research work, attempts have been made to identify water bearing zones, assessment of water quality, mineralogical composition of sediments. The study area is characterized by two different geomorphologies namely the Barind Tract and Flood Plain areas. In the investigated areas, two water bearing zones have been detected within the depth of 50 meter; one is in the Flood Plain area and the other is in the Barind Tract area. Groundwater is more or less acidic to neutral in both the areas while oxidizing environment is present in the Barind Tract area and reducing environment is in the Flood Plain area. The chemical analysis of groundwater sample reflects that the major elements are calcium (Ca), sodium (Na), magnesium (Mg), chloride (Cl), sulfate (SO4), bicarbonate (HCO3) and the minor elements are potassium (K), iron (Fe), nitrate (NO3), nitrite (NO2), phosphate (PO4) and fluoride (F). The trace elements are cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni), zinc (Zn), arsenic (As), lead (Pb) and cadmium (Cd). In groundwater, the concentration of most of the elements are within the limit of DoE standard except Mn, Ca, Mg, HCO3 and F. Minerals like quartz, feldspar, mica, hornblende, chlorite, illite, montmorillonite etc are identified in the sediment samples. The above elements and minerals are playing important roles in terms of groundwater quality. As long as the equilibrium condition of subsurface geochemical environment remains uninterrupted there is less possibility of any significant change in water quality. Thus one has to be careful before taking any water supply scheme.