Article Number: DRJPHET15497032
Vol. 5 (2), pp. 19-27, March 2020
Copyright © 2020
Author(s) retain the copyright of this article
Original Research Article
Uptake of heavy metals by native plants growing around an abandon crude oil refining site in southern Nigeria: A case study of African stargrass
Contamination of the ecosystem with heavy metals is one of the most threats to plants and human health. This study was carried out to evaluate the tolerance and bioaccumulation of heavy metals by African stargrass (Cynodon plectostachyus) growing wild in an abandon illegal crude oil refining sites in southern Nigeria. Soil and grass (Cynodon plectostachyus) samples were collected from two abandon illegal crude oil refining sites, within Delta State. Site A has the following spatial coordinates (Lat. 5.231 N, Long 5.552 E); while Site B has the following spatial coordinates (Lat. 5.592 N, Long. 6.172 E). A control site (non-contaminated) with the following spatial coordinates (Lat. 5.855 N; Long. 6.246 E) was selected to serve as a reference point. These heavy metals (Pb, Ni, Cu, Cd and Fe) concentrations in African stargrass parts (root and shoot) and the corresponding soil sample where the plant was taken from were analyzed, using standard recommended methods. The laboratory results showed that the activities of the illegal crude oil refiners had significant (p ≤0.05) effect on the soil samples and the plant’s parts. The Pb, Ni, Cu, Cd and Fe concentrations varied from 7.55 to 11.19 mg kg-1, 3.64 to 11.07 mg kg-1, 3.72 to 6.50 mg kg-1, 1.86 to 3.01 mg kg-1 and 2031.33 to 2303.67 mg kg-1 in the soil samples respectively. From the laboratory results, the African stargrass has good potential of phytostabilization of Ni, but inferior phytostabilizer, in terms of Pb and Cd. The mean bio-concentration factor for Ni, Cd and Fe of the African stargrass in Site A, was higher than the values recorded in Site B. High concentrations of heavy (toxic) metals at the two study areas, as shown by the results, constitute an environmental hazard both to plants and animals. Results obtained from this study will be useful in designing phytoremediation strategy in crude oil spill regions, and discourage the activities of illegal crude oil refiners within the region.
Keywords: African stargrass, Delta State, heavy metals, illegal refinery, phytoremediation