Concentration, Soil-To-Plant Transfer Factor Determination of Heavy Metals in Udu Area of Delta State, Nigeria

Abstract

Heavy metals in varied concentrations are employed in the production of steel of different grades. Silver, cadmium, cobalt, chromium, and copper are of great importance in achieving this. They are part of the main ingredients in the production processes, which in most cases determines steel grades. The location of an integrated steel plant within Udu community of Delta State resulted in the pollution of the soil of the surrounding communities, most of which are involved in farming and fishing activities. This necessitated the transfer of these heavy metals from polluted soils into edible plants. These were mainly as a result of discharges of effluents, smoke and particulates from stack during production into the soils of the surrounding communities and finally into some edible plants; that are consumed by the communities as vegetables. Soil and leaf samples were collected from six different towns or communities in Udu. The towns are Ujevwu, Aladja, Ovwian, Ekete Inland, Orhuwhorun and Otor-Udu; and the heavy metals analysed are Ag, Cd, Co, Cr, Cu and Fe. These samples were digested using USEPA Method 3050B and the heavy metals were determined using atomic absorption spectrophotometer (AAS). Results obtained showed the following range for transfer factors (TF) in three different edible plants; which are pumpkin plant (Telfaira occidentalis), bitter leaf plant (Vernonia amygdalina) and scent leaf plant (Occinium gratissimum). The range of values obtained for the transfer factors are- Ag: 4.48–196.45; Cd: 44.52–212.79; Co: 0.03–0.46; Cr: 0.38–3.37; Cu: 21.76–102.95 and Fe: 2.85–14.40. For the six sample sites, generally, the values are in the order: Cd ˃ Ag ˃ Cu ˃ Fe ˃ Cr ˃ Co. Result interpretation shows some level of contamination when compared to recommended standard of these heavy metals in plants. The effect of which can be devastating in the future if not checked.