Pollutional Status of Kubanni Lake Through Metal Concentrations in Water and Sediment Columns, Zaria - Nigeria

摘要

The aim of this study is to evaluate the level of pollution of kubanni lake. Concentrations of some metals in water and sediment columns of Kubanni lake were investigated for a 2 year period (2002-2004). Samplings were done monthly at 5 different sites. The concentrations of the metals were determined using atomic absorption spectrophotometer. The pH fluctuated between acidity (6.50) and alkalinity (9.0). The mean temperature, electrical conductivity, dissolved oxygen and hardness are: 24.97±.29℃, 69.20±0.72 μ/cm, 07.25±0.05 mg/ and 124.77±8.11 mg/. CaO_3, respectively. Mg, Ca, Pb, Co, Cd and Cr were detected in all the water samples with means of 1.47±.08, 9.21±0.52, 1.220.05, 1.26±0.05, 0.02±0.01 and 0.86±0.04 mg/L respectively. The dry season means of Mg, Ca and Pb were higher than the rainy season means while a reverse trend was observed for Co and Cr. The sediment metal concentrations correlated positively with the water metal concentrations. The detection of Pb and Cd in Kubanni lake indicates the contamination of the lake's water by human activity. The concentrations of Cr, Cd and Pb in both sediments and water were above WHO recommended limits. Also, the Ca: Mg ratio obtained for Kubanni lake water is 6:1, indicating Mg deficiency of the lake's water. Consequently, the lake water is not suitable for irrigational purposes in terms of Ca: Mg ratio.