Assessment of heavy metal concentration in ipomoea batatas and spinach consumed in Zanzibar by Energy Dispersive X-ray Fluorescence (EDXRF)

Abstract

This work aimed to assess the levels of heavy metal concentration in ipomoea batatas and spinach associated with uncontrolled municipal waste, motor vehicles fumes, pesticides and fertilizer in the urban west region, in Zanzibar. Twenty samples were randomly collected in local markets and three farms located along a roadside in the urban west region. The samples were analysed using an energy dispersive X-ray fluorescence method at Tanzania Atomic Energy Commission in Arusha. Essential and toxic elements: Mn, Cu, Fe, As, Zn, Pb, and Ni were detected in both ipomoea batatas and spinach. Ipomoea batatas was found to have a higher concentration of Cr, Fe, Cd and Zn while spinach had a higher concentration of Ni, Cr and Zn. The essential elements concentrations of vegetables analysed in the current study were found within safety baseline levels for human consumption. However, the concentration levels of toxic elements were above FAO/WHO permissible limits. The higher concentration levels of toxic elements in ipomoea batatas and spinach might be associated with contamination of municipal waste, chicken manure, motor vehicles fumes or pesticides. Therefore, vegetable cultivation along a roadside in the urban west region in Zanzibar and the use of fertilizer and chicken manure in vegetables introducing high levels of heavy metals in the food chain.

Keywords

• Heavy metals
• Ipomoea Batatus
• Spinach and EDXRF