Speciation of Some Trace Metals in Floodplain Soil of Eke-Mgbom, Afikpo, Nigeria

Floodplain soil sediment at Eke-Mgbom, Afikpo, Nigeria, was sampled and subjected to chemical fractionation to reveal the geochemical forms in which some trace metals existed. The investigation was conducted to evaluate the bioavailability of these metals to receptor organisms. The speciation of iron, manganese, copper, zinc, nickel, lead, cadmium and chromium were estimated by the speciation method. The geochemical phases in which the metals partitioned followed the order: Oxidizable >> Exchangeable >> Carbonate > Residual > Reducible. This is an indication that most metals accumulated in humic matter. Percentage bioavailability ranged from 17.7%(Cr) to 52.6%(Cd) with an average value of 34.03%. Other trace metals, apart from copper and cadmium were undersaturated with respect to their availabilities to biota. Proper cleaning methods such as phytoremediation were suggested in order to minimize or keep these trace metals in stable forms in this rural agricultural soil.