Evaluation of Heavy Metal Pollution Level in Soils and Plants around Ibeno Area, Akwa-Ibom State, Niger Delta, Nigeria

Abstract

Soil and plant quality around oil spill sites within Ibeno area, Akwa-Ibom, Niger Delta, Nigeria were investigated in the present study related to oil spills and gas flaring. Soil and plant samples were collected within and outside oil spill area and sent to the laboratory for analyses. Nine heavy metals were analyzed and the results of the laboratory analyses showed that the mean concentrations of cadmium, zinc, and copper were above their respective average crustal abundances thereby signifying pollution. Environmental pollution indices were used in this study to ascertain the source and extent of pollution in the soil and plant samples in the area. It was established that both the soil and plant in Ibeno area are polluted with cadmium, zinc, and copper, while manganese, lead, nickel, cobalt, mercury, and arsenic showed no significant pollution at the time of this research. The established order of pollution starting with the highest are: Cd > Zn > Cu > Pb > Co > Ni > Hg > Mn > As. These findings were further validated by the computed soil-plant transfer factor, as it revealed zinc, cadmium, copper and lead as the dominant metals in the soil and plant in the area. These results were also compared with the average crustal abundance (background value) postulated by Wedepohl as well as Taylor and McLennan, it also confirmed that cadmium, zinc, and copper are the dominant pollutant in soil and plant system. The pollution in the area was attributed to the age long menace of oil spill, gas flaring, dumping of non-functional equipment and machinery in the surrounding soils in the area. The use of environmentally friendly techniques such as bioremediation in the clean-up of the contaminated soil is recommended.