Heavy Metals Presence in Some Vegetables and Crops Harvested From Farms in Ebocha, Egbeda and Igbo-Etche in Rivers State, Nigeria

Abstract

Studies of the presence of heavy metals were carried out on some vegetables and crops harvested from farms in Ebocha, Egbeda and Igbo-Etche in Rivers State, Nigeria. These farms are located in communities where oil exploration activities are ongoing. The samples were prepared by wet digestion using a mixture of Perchloric acid (HClO4): Nitric acid (HNO3) in the ratio 1:4 and analyzed using Atomic Absorption Spectroscopy (AAS). The heavy metals concentration in almost all the vegetables and crops studied were high compared to the maximum permissible limits prescribed by World Health Organisation (WHO), Food Agriculture Organization (FAO) and European Union (EU) except Zn. The concentrations of these metals in the vegetables and crops studied are Co (0.10 – 3.88 mgkg-1), Pb (3.34 – 11.27 mgkg-1), Zn (4.21 – 94.34 mgkg-1), Cd (0.03 – 6.97 mgkg-1), Ni (0.10 – 5.70 mgkg-1), Mn (1.65 – 109.86 mgkg-1), Cu (2.15 – 16.11 mgkg-1) and Fe (22.20 – 334.97 mgkg-1). Concentrations of Co are within acceptable limits except in bitter leaf, scent leaf and water leaf from Ebocha (Site 1) farm which were 2.44 mgkg-1, 2.27 mgkg-1 and 3.78 mgkg-1 respectively. Waterleaf from Igbo-Etche farm recorded a concentration of 3.88 mgkg-1. From the results obtained in this study, the tuberous crop (cassava) has higher concentrations of the metals in comparison to the plantain. The order of the levels of heavy metal concentration in the vegetables and crops is presented in the decreasing order of Scent Leaf > Water Leaf > Fluted Pumpkin >Bitter Leaf > Cassava > Plantain. From the four farms, the levels of concentration is Igbo-Etche>Ebocha 1 = Ebocha 2 > Egbeda. Analysis of variance [ANOVA] confirmed significant differences (P<0.05) among the heavy metals present in the vegetables and the crops from these four farms.