Comparative Evaluation of Proximate Compositions and Heavy Metal Profiles of Three Vegetables Collected in Some Locations in Ikorodu, Nigeria

Abstract

Vegetables are bio-stores of nutrients required for the effective and smooth running of human body. However, due to soil pollution, vegetables grown often take up heavy metals which cause damages to vital organs in the body. Thus, this research aimed at comparatively assessing the proximate compositions and heavy metal profiles’ of Talinum triangulare, Corchorus olitorius and Solanum macrocarpon collected from farmlands, roadsides, and markets in some locations in Ikorodu, Lagos State, Nigeria. Leaves of S. macrocarpon, C. olitorius and T. triangulare were collected from farmlands, markets, and roadsides across three different locations in Ikorodu; proximate and heavy metal assessments were done using Atomic Absorption Spectrometry. Data obtained were subjected to mean-standard deviation; means were separated using analysis of variance (P≤0.05). Proximate analyses revealed that the vegetables contain appreciable moisture, lipid, ash, protein, fiber, and carbohydrate quantities. Heavy metal analysis revealed the ranges of Zn (0.2746-0.4710mg/Kg), Co (0.0004-0.0007mg/Kg), Cu (0.0442-0.0760mg/Kg) and Mn (0.0002-0.0008mg/Kg) for farmlands; Zn (0.2746-0.5271mg/Kg), Co (0.0004-0.0008mg/Kg), Cd (0.0006mg/Kg), Cu (0.0320-0.1061mg/Kg) and Mn (0.0003-0.0008mg/Kg) for markets; Zn (0.3403-0.5610mg/Kg), Cu (0.0361-0.0930mg/Kg) and Mn (0.0002-0.0008mg/Kg) for roadsides. Pb and Ni were not detected in the vegetables across different locations. Also, all the metals studied were within World Health Organization’s permissible limits. This may be due to the regulation of heavy metal availability in plants by the metal matrix concentration in soils. The study, however, suggest that areas with a high concentration of industrial factories and busy roads should not be used for vegetable cultivation to limit plant uptake of heavy metals discharged into the soil