Investigation of the Presence of Some Heavy Metals in Four Edible Vegetables, Bitter Leaf (Vernonia amygdalina), Scent Leaf (Ocimum gratissimum), Water Leaf (Talinum triangulare) and Fluted Pumpkin (Telfairia occidentalis) from a Cottage Farm in Port Harcourt

摘要

One of the sources of heavy metals contamination is atmospheric pollution from the use of fossil fuel, traffic density and dust. This research was carried out to investigate the presence of Cr, Mn, Ni, Co, Cu, Cd, Zn and Pb were investigated in four of the most commonly consumed vegetables in the Southern part of Nigeria. These vegetables are fluted pumpkin (Telfairia occidentalis), Bitter leaf (Vernonia amygdalina), Scent leaf (Ocimum gratissimum) and Water leaf (Talinum triangulaire). The metal analysis results showed the concentrations (mg/kg) as follows; Cr (1.50-10.25), Mn (9.75-62.75), Ni (15.75-19.25), Co (1.75-3.00), Cu (7.75-11.00), Cd (1.25-1.50), Zn (79.75-186.95) and Pb (6.25-8.00). The concentrations of the metals are in the order of Zn＞Mn＞Ni＞Cu＞Pb＞Cr＞Co＞Cd. Water leaf has the highest concentration of the metals Zn, Mn, Ni, Co, Cr and Cd. Fluted pumpkin has the second highest concentration of Mn and the highest for Cu. The leaves under study reveal high concentrations of these heavy metals which were found to be above the FAO and WHO acceptable limits. These high values can be attributed firstly to atmospheric pollution as the cottage farm is a few meters away from a major highway and most of these metals are constituents of fossil fuel and machinery. Ni, Cd and Pb are classified as carcinogens. This therefore implies that the consumption of these vegetables will eventually lead to serious health problems in the organs and circulatory systems.