Accumulation of Essential and Non-Essential Trace Metals in Soil-Plant System in Parts of Southeastern Nigeria

Abstract

Some essential trace metals (Fe, Cr, Cu, Mn, Mo, Ni, Se and Zn) and non-essential trace metals (As, Cd, U and V) were measured in soil and plant samples collected within the vicinity of Okpoma, SoutheasternNigeria, that stretches into Cameroon and they were analysed using Atomic Absorption Spectrophotometer (AAS). The results of the chemical analyses showed that Fe has the highest concentration in the soil samples followed by Zn, Mn, Cu, Ni, Cr, U, V. The level of accumulation of these metals in different plant parts was in the order the leave>stem>root. High transfer factor values >1.0 revealed strong accumulation of Zn, Cu, Cd, Se, As, U and V in leaves and Cd and As in stems. The major source of these metals is geogenic with minimal contribution from human activities. The total metal concentrations in the soils are the main controls on their accumulation in plants. Essential trace metals (Iron (Fe), Chromiun (Cr), Copper (Cu), Manganese (Mn), Molydenum (Mo), Nickel (Ni), Selenium (Se) and Zinc (Zn) ) and non-essential trace metals (Arsenic (As), Cadmium ( Cd), Uranium (U) and Vanadium (V) occur naturally in rock and soil but in form of constituent and replacement minerals in rock and soil minerals. High concentrations of these metals are being released into the environment by human activities such as agricultural processes (1-3). Among the sedimentary parent materials, shales potentially contribute the highest concentration of these metals (4). Edible crop plants grown on soils enriched with metals may be accumulating these metals to levels that may be deleterious to human health when