Phyto-extraction of nickel, chromium, lead and copper from crude oil polluted agricultural soil

Abstract

The phyto-extraction of heavy metals, nickel, chromium, lead and copper from crude oil polluted agricultural soil was carried out using four annual indigenous crops, including two annual forage leguminous crop, vegetable cowpea (Vigna unguiculata var unguiculata) and velvet bean Mucuna pruriens; a cereal- maize (Zea mays) and a vegetable crop- fluted pumpkin (Telfaira occidentalis). The level of attenuation of the four heavy metals was determined using atomic absorption spectrophotometer (AAS). The results obtained showed that the copper, nickel, lead and chromium contents (40.20, 39.10, 0.96 and 7.38 nmoles/mg respectively) of the control sample were significantly higher (p<0.05) than the values obtained from the oil polluted soil samples, depicting that there was an uptake of the heavy metals from the polluted soils. There was no significant difference (p>0.05) in the rate of uptake of these metals by the plants irrespective of the location of the study.

Keywords: Phyto-extraction, heavy metals, crude oil, agricultural soil, pollution