<b>Comparison of Levels of some Metals in the Water and Sediment from Challawa Gorge Dam, Kano, Nigeria</b>

Abstract

Level of some Metals (Cd,Cr,Mn,Pb,Zn,Na and K) was seasonally determined in the water and sediments of Challawa Gorge dam.The result obtained showed that the values of the metal contents were generally higher in the dry season than the wet season. The metal contents of the water and sediment were obtained using the nitric acid digestion method. All the metals analyzed except Na and K were determined using Atomic Absorption Spectroscopy (flame emission spectroscopic method). Variations in concentrations were found for the heavy metals ranging between (0.01and1.41mg/l) in water and (1.0 and 1.64 mg/kg) in the sediments. Sodium and potassium were found in concentrations ranging between 7.65±0.28 and 11.32±8.62mg/l in water and between 50.32±18.08mg/l and 144.19±12.09mg/kg in the sediments respectively. The statistical comparison of the values between the wet and dry season in water as well as those in sediment shows no significant difference at P>0.05. All the metals were found to be within the permissible limits as recommended by WHO/NOAA for quality water and sediments except for the levels of iron (Fe) in water which was found to be above the acceptable limit. The sediments contained higher concentration of heavy metals than the water. This may be attributed to the fact that sediments usually serves as repositories in an aqueous environment.

Keywords: Heavy metals, sediment, wet season, dry season, water.