Phytoremediation potential of sorghum (Sorghum bicolor (L) Moench) and African yam bean (Sphenostylis sternocarpa) Hoechest ex A. Rich) harms on crude oil polluted soil

Abstract

A study on Phytoremediation potential of Sorghum (Sorghum bicolor) and African yam bean (Sphenostylis sternocarpa) on crude oil polluted soil was conducted in the botanic garden of university of Port Harcourt. 30kg of soil was weighed and put into planting bags. 100ml. 200ml, 400ml and 800ml of crude oil were measured using measuring cylinder and mixed with the soil and the untreated soil sample (control). These served as treatments and were replicated 5 times. After two weeks of pollution, viable seeds of Sorghum bicolor and Sphenostylis sternocarpa were planted and morphological and physico- chemical parameters were taken and the data collected were subjected to Analysis of Variance. The result shows that the biomass of the untreated soil sample (control) was found to be the highest, while the 800ml treatment recorded the lowest, The morphological parameters are Plant Height, Number of Leaves and Leaf Area. At week 12 for sorghum, treatments(1,2,3 and 4) concentration of crude oil had mean Plant height of 65.28cm,65.56cm,63.5cm and 59.9cm respectively while control had 66.77cm.For Number of leaves, treatments(1,2,3,and 4) had 74cm,75cm,76cm,and 69cm respectively while control had 78cm.For Leaf Area treatments.(1,2,3,and 4) had 320cm 2 , 311cm 2 , 281cm 2 and 269cm 2 respectively while control had 341cm 2. .That for African yam bean, treatments(1,2,3,and 4) had mean Plant height of 66.78cm,67.62cm,64.04cm,and 28.72cm respectively while control had 72.82cm.For Number of leaves treatments {1,2,3,and 4} had 123cm,123cm,121cm,and92cm respectively while control had 127cm.For Leaf Area treatments(1,2,3,and 4) had 103cm 2 , ,99cm 2 ,91cm 2 ,and 77cm 2 while control had 116cm 2 . The heavy metals analyzed in the soil (control) before planting are Zinc = 0.342g/ml, lead = 0.188g/ml and Nickel = 3.49g/ml while
the soil polluted with crude oil: Zinc = 1.719g/ml lead = 0.256g/ml and Nickel = 4.245g/ml. The heavy metal content of sorghum analysed for after 12 weeks are Zinc = 0.13g/ml, lead = 0.14g/ml and Nickel = 0.175g/ml while that of African yam bean analyzed for are Zinc = 0.14g/ml, Lead = 0.16g/ml and Nickel = 0.179g/ml. Lastly heavy metals found in the soil at the end of 12 weeks was Zinc = 1.449g/ml, lead = 0.44g/ml and Nickel = 3.891g/ml. Result from the experiment shows that sorghum is a better phytoremediating plant than African Yam bean.