Assessment of the quality of revegetated soil near an active goldmine in southwestern Ghana

Abstract

This study presents an assessment of soil quality of revegetated locations within the catchment of a goldmine, using the index of geo-accumulation, enrichment factor and multivariate statistics. Fourteen composite soil samples were analyzed for the following parameters: Mn, Cd, Pb, Fe As, pH, organic C, organic matter, available K and P, total N, total exchangeable base, exchangeable acidity, effective cation exchange capacity and base saturation. The results indicate that all locations except one were practically uncontaminated with Fe. Three locations were practically uncontaminated with Mn, whereas all other locations were uncontaminated to moderately-contaminated. Principal component and cluster analyses indicate that most members form one cluster suggesting uniformity in the degree of impacts on the soils with regard to the parameters analyzed; and further signifying that the impacts possibly originate from a common source. 93% of the locations recorded low to very low levels of N (0.04-0.14mg/kg). 15% of the soils show medium levels of available P (8.45- 9.81mg/kg) while the other locations (85%) show very low levels (0.01-1.59mg/kg), an indication that most of the soils are phosphorous deficient. The mean ECEC was 8.5meq/100g and ranged from 3.66meq/100g to 17.12meq/100g. 28% of locations recorded less than 5meq/100g CEC, which is the minimum level for adequate exchange capacity according to the Ghana Soil Fertility Capacity Classification. Though the heavy metal concentrations in the soil do not pose any significant risks to agronomic activities, the nutrient / fertility status is low to medium. There will therefore be the need to fertilize to correct the various nutrient deficiencies prior to the commencement of agronomic activities