Metal Burden as Template for Assessing the Quality of Raw Water Sourced from Two Rivers by Lagos State Water Corporation, Nigeria

Abstract

Water and surface sediment samples from three different points of River Owo at Isashi and Ogun River at Akute Odo were collected and quantitatively analyzed for metals burden. The two rivers serve as sources of raw water processed by the Lagos State Water Corporation for domestic and industrial consumption. The levels of lead, cadmium, copper, calcium and zinc in the samples were determined by atomic absorption spectrometry. The results obtained revealed high mean values of calcium in both water and sediment samples. Metals concentration (mg/l) in water samples are within the Nigeria’s background values (NBV): ND–0.46 (Pb), ND–0.35 (Cd), ND–0.78 (Cu), 8.47–330.00 (Ca) and ND–1.89 (Zn). However, cadmium and calcium levels in sediment samples exceeded the NBV (μg/g) with ND–2.02 and 0.24–87.50 respectively. Similarly, with the exception of lead and cadmium, all other metals in the water samples are found to be within the World Health Organization (WHO) limit set for drinking water. Correlation coefficient and statistical t-test were used to test for statistical significant differences at 95 % confidence level. The levels of cadmium and lead especially in the water samples give cause for concern considering their potential health risk.