A Case Study of Heavy Metal Concentrations in Soil and Leafy Vegetables from Roadside Gardens in Lagos, Nigeria
Odjegba, V.J.*, Ejogbamu, O.P. and Kukoyi, A.
Department of Botany, University of Lagos
Akoka, Lagos, Nigeria.
*Correspondence: jodjegba@unilag.edu.ng Tel:08023323406
Accepted on July 14, 2012
Abstract
The concentrations of lead, cadmium and copper in soil and leafy vegetable from roadside gardens in Lagos were investigated. Soil and plant samples were collected from gardens along three major highways where roadside farming is a common practice at a distance of 10 meters away from the roadside. The control soil samples were collected 200 meters away from the roadside at each of the three locations. The concentrations of the three metals in the samples were measured using Flame Atomic Absorption Spectrophotometry (FAAS). The concentration of lead was the highest in soil and plant samples from the roadside gardens at the three locations, and varied from 21.35 ± 0.18 to 24.79 ± 0.22 mg kg-1 in garden soils, while its mean levels in the aerial portion of the vegetable varied from 14.36 ± 0.40 to 15.22 ± 0.30 mg kg-1 dry wt. The control soils however had significantly low levels of lead which varied from 1.89 ± 0.02 to 3.43 ± 0.09 mg kg-1, while the mean levels of copper ranged from 6.92 ± 0.02 to 7.36 ± 0.01 mg kg-1. Concentrations of the three metals in the vegetable were more in the root tissue than the shoot. It was established in this study that the high levels of these metals in soil and plant samples from the roadside gardens was directly related to the vehicular traffic on the highways at these study sites.