Heavy Metal Pollution and Mobility in Soils within a Landfill Vicinity: A South African Case study

Abstract

Heavy metal contamination in soils results from anthropogenic and lithologic factors and is a potential hazard to land and water resources. Sources of such pollution include landfills, domestic sewage, agricultural fertilisers and industries. In this work, soils from Roundhill landfill vicinity in South Africa were sampled and analyzed to determine the concentrations of particular heavy metals, namely As, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn. The main objectives of this work were to: quantify the concentration levels of heavy metals in the soil; determine the mobility of the heavy metals in the soil; and establish their origins and interrelationships. The soils were collected at various distances and depths from the landfill facility. The concentrations of heavy metals in the soil samples were analysed by ICP-MS and statistical analysis was carried out to establish their relationships and sources. From the analysis, some elements including Cr, Mn, Cu and Ni had measured concentrations beyond the threshold limits in most sampling sites irrespective of their distance and depth from the landfill vicinity. Conversely, some elements were observed to be immobile and had higher concentrations on the top soils closer to the landfill, such as As, Pb, Zn, Co and V. Iron (Fe) had high concentrations in all the sampling sites due to its natural occurrence in the parent rocks. In conclusion, the potential of soil quality deterioration due to heavy metal pollution in a landfill vicinity was observed. Furthermore, all heavy metals observed showed positive correlation to each other except for As and Co, indicating same origin.