Assessment of heavy metal pollution on some edible crop trees from vehicular movements on road side within University of Port Harcourt

Abstract

The heavy metal from five selected tree plants [Mangifera indica (L.), Elaeis guineensis(Jacq.), Prunus dulcis (Mill), Citrus sinenesis (L) and Psidium gujava (L.)] in the University of Port Harcourt were analysed for its content in the leaves and soil. The leaves of edible trees and soil far from the major roads were used as a control. The digestion method was used for analysis of heavy metals and the heavy metals in soil were analysed by atomic absorption spectrophotometer with spectra AA 650. The results obtained indicate that concentration of Lead was between 12.85-35.57 and 10.57-25.17 mg/kg for soil and leaves across sampled sites. Nickel ranged between 0.00-28.87 and 0.00-0.02 mg/kg for soil and leaves respectively. Copper was between 2.27-13.69 and 1.33-10.58 mg/kg for soil and leaves. Zinc had a ranged of 2.40- 17.53 and 2.40-9.33 mg/kg for soil and leaves. Aluminium presented a
range of 0.04-0.93 and 0.04-0.67 mg/kg for soil and leaves across sampled sites. Lead showed significant presence as compared to other sampled metals in both soil and leaves in all plants across locations, Ni showed presence in Choba and Delta Parks for orange, almond and oil palm plants and absence in other sites (University Park and UPTH); with noticeable absence in mango and guava across the four sampled locations. The concentrations of Pb and Zn in the leaves of sampled plants exceeded the recommended intake considered suitable for humans while the concentrations of Cu, Ni and Al were within the range for human consumption. However, heavy metal concentrations were higher in sampled locations compared with the control as a result of exhaust from automobiles as the main source of these heavy metals pollution in plants and soil. Hence, edible crops like those from this study should not be planted along major roads to avoid pollution by heavy metals from vehicular movement.