Assessment of heavy metals in contaminated soil and waterleaf (talinum triangulare) cultivated from selected dumpsites in Port Harcourt, Nigeria

Abstract

Heavy metal levels such as copper, magnesium, vanadium, cadmium, and cobalt were examined in dumpsite soil and one species of leafy vegetable Talinum triangulare (waterleaf) from three (3) locations of Port Harcourt metropolis, Rivers State, South-South, Nigeria. The samples were digested with a 3:1 mixture of mineral acids, HCl and HNO3 were assessed following the procedure of Atomic Absorption Spectrophotometer (AAS). The results obtained showed that Magnesium (Mn) was the most abundant metal, with the highest concentration observed at the Port Harcourt - Town dumpsite in both the soil (4.679±0.085) Mg/kg and the leaf (4.382±0.031) Mg/kg. The least concentrated metal in the dumpsites was Cadmium (Cd) in both the soil and the leaf with the lowest value observed at the Trans Amadi (0.012±0.055) Mg/kg dumpsite for the soil and Eleme – Junction (0.001±0.019) mg/kg dumpsite for the leaf. The order of the metal concentrations in the dumpsites for both soil and leaf was Mn>Cu>V>Co>Cd. All the metals except cadmium (Cd) were below the required permissible limit in soils by WHO/FAO (2001). All the metals except Cobalt (Co) were below the required permissible limit in waterleaf (Talinum triangulare). The contamination factor showed that the soils were within the uncontaminated – moderately contaminated in the various dumpsites for all the metals except Cd which was slightly – moderately contaminated and Co which showed signs of contamination shortly. The contamination factor (Cf) and transfer factor (Tf) also revealed that dumpsite soils and vegetable (Talinum triangulare) leaves accumulate higher metal concentrations. This portends health risks for consumers of waterleaf (Talinum triangulare) and other farms produced concerning the heavy metals examined in the studied area.