Distribution of Trace Elements in Surface Water and Sediments from Warri River in Warri, Delta State of Nigeria

The pollution of surface water and sediments by heavy metals has become a difficult thing to deal with due to their toxicity and accumulative behavior. The present study was undertaken to provide information on the concentrations and distribution of selected heavy metals in surface water and sediments from Warri River, and to compute a contamination/pollution index of heavy metals. Surface water and sediment samples were collected using standard methods and then analysed for nine trace metals. These metals were determined using a Flame Atomic Absorption Spectrophotometer – UNICAM 929. According to our results, the mean concentrations of the select metals in the sediments were higher than those of the surface water. The figures, however, varied significantly in the six sample locations (SW1–SW6). In the sediments, the highest mean concentration was of Fe (504.13 mg/kg) in location SW1, whereas in surface water, generally, the highest mean concentration was of Fe (1.23 mg/l). In other words, mean metal levels in the sediments exceeded those of surface water. This indicates that sediments are a sink for metal pollution loads. Computation of contamination/ pollution index in sediment matrix revealed that Cd moderately polluted the sediment, Zn, Fe, Ni slightly, yet significantly contaminated the sediment, while Cu, Cr and Mn very slightly contaminated the sediments. The mean values of metals in this present study were compared with other values reported by other researchers. The higher than normal metal values were attributed to anthropogenic wastes, runoff, refinery jetty and varied petroleum related activities in the area.