Seasonal Variation and Determination of Some Heavy Metals in the Sediment from Ureje River in Ado-Ekiti, Nigeria

Abstract

This study investigated the level of contamination of four heavy metals (chromium, cadmium, nickel, lead) in the sediment
collected from Ureje River, Ado Ekiti, Nigeria and compared their seasonal variation (Wet and Dry seasons). The sediments
were collected, digested and analyzed using Atomic Absorption Spectrophotometer (AAS). Two of the metals namely
cadmium and nickel were not detected. During the dry season, it was observed that the mean concentrations for chromium
were 0.36±0.08 mg/kg, 0.33±0.08 mg/kg and 0.30±0.04 mg/kg for Sites 1, 2 and 3 respectively. The mean concentration for
lead during dry season at Site 1 was 0.33±0.23 mg/kg while those of Sites 2 and 3 were 0.35±0.10 mg/kg and 0.34±0.04
mg/kg respectively. During the wet season, chromium levels were 0.23±0.06 mg/kg, 0.25±0.06 mg/kg and 0.21±0.03 mg/kg
for Sites 1, 2 and 3 respectively. For lead, the values recorded for Sites 1, 2 and 3 were 0.22±0.11 mg/kg, 0.30±0.10 mg/kg
and 0.26±0.03 mg/kg respectively. Comparing the two seasons, the concentration of chromium was observed to be lower
than that of lead in the dry season while the reverse was the case during the wet season. Although the concentration of the
metals is unlikely to pose any risk, the presence of chromium and lead in the area calls for proper monitoring to safeguard
the health of human and aquatic lives around the area.