Toxicological Assessment of Crops Grown in Soils Amended with Municipal Solid Waste Ash

Abstract

This study assessed heavy metals (As, Cd, Cr, Cu, Pb, Ni, Fe and Zn) in sites and food crops (beans and groundnuts) harvested from farmland amended with municipal solid waste (MSW) ash. Farmlands with no amendments and crops grown on such soils served as control. Soils and crops samples were collected at full maturity to determine soil levels (mgkg-1), translocation in crops and accumulation index of metals. The crops were separated into roots, leaves and grains before analysis and heavy metals were determined using VGB 210 Atomic Absorption Spectrometer. Mean concentrations (mgkg-1) of studied metals were 0.053±0.03, 0.053±0.01, 648.55±1.07, 168.699±1.05, 36.514±4.66, 339.53±0.12, 232.331±0.69 and 363.482±0.00 in test soils and 0.010±0.10, 0.050±0.01, 83.333±1.00, 38.618±1.03, 2.913±0.00, 163.248±0.22, 41.579±3.01and 82.798±0.28 in control soils for As, Cd, Cr, Cu, Ni, Pb, Fe and Zn respectively. Observed levels for test soils were significant (p≤0.05) in comparison to those of the control and were highest for Cr, Cu, Ni, Fe and Zn. Metals concentrations in the tissues of beans and groundnut grown on both sites were found to be decreasing in the order roots > leaves > grains. Levels of As, Cr, Cu, Ni and Fe fell below the WHO standard while Cd, Pb and Zn exceeded those set limits. Translocation factors for beans and groundnut cultivated on test site indicated effective translocation of arsenic from soils to the roots. Observed pattern has health implication for raised fodder for animal husbandry in such areas. Similarly, the geo-accumulation index of both test and control sites revealed they were polluted with Zn, Cr, Ni, Cu, Ni, Cu and Fe.