Assessment of Heavy Metals in Soils and Zea mays Plant from Farmed Dump Sites in Tubah Subdivision-Northwest Cameroon

Abstract

This study assessed the physicochemical and heavy metal properties of soil and the risks associated with Zea mays contamination by heavy metals in farmed dump sites in Tubah Sub-division, Northwest Cameroon. Three surface soil samples (0-20 cm) and Zea mays plant samples were collected from Bambili (S1), Baforkum (S2) and Bambui (S3) and analyzed following standard analytical procedures. Results of physicochemical analysis showed that all the soils had low pH values (5.45-6.12), moderate organic matter content (3.93% - 7.14%), and high available phosphorus (9.51-52.58 mg/kg). Total heavy metal concentrations for all soil samples ranged from 4.66-5.23 mg/kg, 65.32-98.12 mg/kg, 1555.12-2158.65 mg/kg, 94.64-115.34mg/kg, 0.87-1.01 mg/kg, 96.54-156.3 mg/kg, and 289.43-450.48 mg/kg for Cd, Pb, Mn, Cu, Hg, Cr and Zn respectively. Total heavy metal concentrations in Zea mays plant ranged from 2.66-4.33 mg/kg, 21.32-28.21 mg/kg, 55.12-230.34 mg/kg, 8.64-34.23 mg/kg, 0.47-0.81 mg/kg, 53.43-76.3 mg/kg, and 89.43-108.48 mg/kg for Cd, Pb, Mn, Cu, Hg, Cr and Zn respectively. This study thus revealed that the soils and Zea mays plants were contaminated to varying degrees by the heavy metals Cd, Mn, Cu, Hg, Cr and Zn, and consequently, there are potential health hazards associated with the consumption of Zea mays cultivated on these soils. Physical remediation (capping, washing of soil, excavation of soil), chemical remediation (immobilization, solidification, vitrification), and phytoremediation can be employed to recover heavy metals from such soils, meanwhile, lime-induced immobilization of heavy metals could assist to keep the metals in the soil in an insoluble state.