Speciation of trace metals in sediment of a tropical river

Concentrations and speciation of Pb, Cu, Cr, Cd, As, Ni in sediment from New Calabar River, Nigeria were assayed. Concentrations of the trace metals were determined using UNICAM solar 969 AAS. Speciation was done using five steps sequential extractions. Results revealed that for wet and dry seasons, concentrations (mg/kg) of the metals in the sediment ranged from 1.1E-2±1.0E-3 for As to 5.17±0.04 for Ni and that majority of the metals were bound to the residual fraction (F5), while Cu was mostly bound to the exchangeable fraction (F1). Overall trend of speciation indicated that Cr was higher in F5 and lower in fraction bound to organic matter (F4). It also indicated that Cu was higher in F5 and lower in F4 and that Pb was higher in F1 and lower in F4; Ni higher in F5 and lower in F4. The study has indeed provided data and information on the pollution status of the river.