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Abstract
In many agricultural settings, the high cost of inorganic fertilizers has led farmers to resort to using compost from large dumpsites for soil amendment, in some cases, farmers even level smaller dumpsites and utilize the land for crop cultivation. This study investigated the concentrations of trace metals (Cd, Cr, Cu, Mn, Ni, Fe, Pb, Zn) in dumpsite compost, soil for cultivation, maize plants, and spinach vegetables. The study results revealed significant variations in heavy metal levels across the different samples analysed. Dumpsite compost exhibited elevated concentrations of Cd (6.00 mg/kg), Cr (89.00 mg/kg), Cu (21.00 mg/kg), Mn (101.00 mg/kg), Ni (17.12 mg/kg), Fe (1570.02 mg/kg), Pb (29.31 mg/kg), and Zn (315.18 mg/kg), surpassing the EU limits for Cd, Cu, Ni, Pb, and Zn. Conversely, soil for cultivation showed low concentrations of heavy metals, for Cd is (0.40 mg/kg), Cr (21.31 mg/kg), Cu (1.72 mg/kg), Mn (12.98 mg/kg), Ni (2.43 mg/kg), Fe (520.11 mg/kg), Pb (0.98 mg/kg), and Zn (67.31 mg/kg), still exceeding EU limits for Cd, Cr, Mn, Ni, and Zn. Maize plants and spinach vegetables showed varying levels of heavy metals, with concentrations generally lower than those in dumpsite compost but still exceeding the EU limits for several metals. The metal uptake by plants followed the order Cd > Pb > Cu > Ni > Cr > Zn > Fe > Mn. Thus, this study underscores the potential health risks associated with consuming crops grown on heavy metal loaded compost/soil and highlights the importance of continuous monitoring and remediation efforts to ensure food safety and environmental health.
