Assessing the Potential Ecological Risks of a 12-Year Old Reclaimed Post-Mined Site for Agricultural Land-Use

Abstract

Mining is a crucial component of local and global economies, but it inevitably leads to substantial environmental disturbance. Reclamation ensures that a disturbed land is rehabilitated for a specified end land-use. The study examined the nutrient levels and risks status of a twelve-year old reclaimed site to ascertain its suitability for agricultural land-use. Twenty subplots of dimensions of 10m x 10m were laid within the reclaimed plots whereas 10 subplots where laid within adjacent undisturbed cocoa farm as control plots. Generally, the concentrations of all heavy metals and exchangeable cations of the reclaimed site’s soil were significantly higher than the control plots and so were their respective cumulative potential ecological risk (PERI). The level of heavy metals contamination followed the order: Fe > As > Ni > Cu > Zn > Pb. Among the observed cations, only Magnesium (Mg) had the highest correlation with 60% of the variables of the study. The geostatistical analysis obtained by interpolation of risk values of the respective sites and classification into the risk categories revealed that the reclaimed area poses a “considerable ecological risk” (approximately 59% of the study area) due to the heavy metals’ contamination. Thus, whiles the exchangeable cations concentrations favour agriculture, the potential ecological risks of the reclaimed site due to heavy metals’ contamination made it unsuitable for agricultural land-use. The study has provided empirical evidence that would guide policy on decommissioning and release of post-mined reclaimed lands to communities for a specified end land-use in support of their livelihoods.