Heavy metal content in dumpsite soils and vegetables: A case study of Ondo Town, Nigeria

Abstract

The investigation scrutinized the levels and distribution of five heavy metals (iron, cadmium, copper, lead, and nickel) at two dumpsites (Site A and Site B) and a control zone in Ondo Town, Nigeria. Moreover, the examination assessed the presence of these heavy metals in vegetable plants (Talinum triangulare and Chromolaena odorata) commonly encountered in these areas, employing atomic absorption spectrophotometry (Buck AAS 210 VGP). Conventional methodologies were utilized to evaluate specific soil physicochemical characteristics. In the control region, minimal levels of each metal were identified, with the exception of nickel. The quantities of metals varied, with lead at 0.02 mg/kg in the control area and iron at 3.54 mg/kg in Site A. The metal levels in both soil and vegetables investigated generally remained below the maximum thresholds established by the World Health Organization (WHO) for soil and vegetables, except for cadmium in Site A. The dumpsites and the associated vegetables displayed elevated levels of the heavy metals in comparison to the control area, suggesting a gradual accumulation of these metals in the vegetable flora. Hence, the consumption of vegetables cultivated near the examined sites and the use of these areas for agricultural activities should be discouraged.