Brief Overview of Heavy Metals in Edible Vegetables at Abandoned Solid Waste Dump Sites in Port Harcourt, Nigeria

The concentrations of eight selected heavy metals, Pb, Cd, Cu, Ni, Cr, As, Hg, and Zn in seven
consumable vegetables harvested at some dump sites and farm lands ( as control) in Port Harcourt
and its environs in Rivers State Nigeria were investigated. The soils in which they are grown were
also analysed using Solaar Thermo Elemental Atomic Absorption Spectrometer (AAS) model SE
71906. The vegetables plants investigated were Bitter leaf (Vernonia Amgdylina, Pumpkin (Telfairia
Occidentalis), Green Vegetable (Amaranthus hybridus), Okro plant (Abelmoschus esculentus L),
Green Amaranths (Amaranthus viridis). The results obtained show that the concentration of heavy
metals in the dumpsites were significantly higher (P<0.05) and varies from the results for the
farmlands (control). Similarly there were more heavy metals in vegetables harvested at dumpsites
than the control sites. Zn concentration in vegetables at both sites Zn (31.6 ± 0.23 - 68.04 ± 0.1
mg/kg) and Zn (10.36 ± 0.18 - 26.62 ± 0.26 mg/kg) respectively. Concentration of other metals
followed the order, Ni> Cu>Cr>Pb>Cd >As. Concentrations of Pb, Cd, Cr in all the vegetables from
the dumpsites were extremely higher than the WHO permissible standard limit. While the Ni, Cu were
below permissible limit only in some vegetables. Hg concentration was minimal in dumpsite
vegetables and was not detected in samples from the control sites. The significantly high level of
heavy metal concentrations, above the World Health Organization (WHO) permissible limits, indicates
bioaccumulation in the vegetables and subsequent bioavailability when consumed. This can pose
great health risk to humans and animals through the food chain.