Heavy Metal Pollution in Soils at Informal Waste Electrical and Electronic Equipment (WEEE) Recycling Sites in Benin

Abstract

Introduction: Informal management of Waste Electrical and Electronic Equipment (WEEE) can lead to the release of heavy metals into surrounding soils, posing environmental concerns. Aims: This study aims to assess heavy metal contamination in soils at informal WEEE management sites in three cities of Benin (Abomey-Calavi, Cotonou, and Natitingou). Methodology: Soil samples were collected from informal WEEE sites and analyzed for eight heavy metals including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn). Metal concentrations were determined using atomic absorption spectrometry and UV Visible spectrophotometry. The geoaccumulation index (Igeo) was applied to evaluate the degree of soil contamination. Results: The results showed very low metal concentrations at non-burning sites, with negative or zero Igeo values (class 0), indicating the absence of pollution. Only isolated cases of cadmium reached class 1 (unpolluted to moderately polluted). In contrast, the burning site in Abomey-Calavi exhibited extreme contamination levels, particularly for Cd (119.08 mg/kg, Igeo > 9, class 6), Pb (503.02 mg/kg, class 5), and Cu (416.97 mg/kg, class 4). Conclusion: These findings highlight the significant impact of open burning practices at informal WEEE sites, which create severe soil pollution hotspots and pose substantial risks to environmental quality and public health.