Analysis of particle size distribution of landfill contaminated soils and their mineralogical composition

Abstract

The particle size distribution (PSD) of soil influences its micro- and macro-structure although individual particle roles in relation to the elemental and mineralogical composition is rarely understood. This study aimed at conducting a PSD analysis of soils from the Roundhill landfill vicinity and interrelating the results obtained with their mineral and elemental characteristics. Soils were collected from nine sampling sites in the landfill vicinity and the particles were analyzed using sedimentation analysis, scanning electron microscopy (SEM), and image analysis. Elemental oxides and minerals in the soils were assayed using X-ray fluorescence (XRF) and X-ray diffraction analysis (XRD), respectively. Clay particles were in the majority at a range of 65–89% and 92–99%, according to sedimentation and image analysis, respectively. Soils of the area were mainly siliceous, containing quartz, and were enriched with aluminum. XRF confirmed these results, where oxides of Si and Al were in the majority. Soils were contaminated with Co, Cu, Cr, Ni, Pb, V, and Zn oxides, according to the XRF results. The ability of clay to adsorb, scavenge, and retain heavy metals explained the presence of these contaminants in the soils.

Keywords:

• Clay
• contamination
• heavy metals
• PSD
• minerals
• oxides

Acknowledgments

The Global Consulting Laboratories of the Eastern Cape are acknowledged for the help offered in soil sampling and transportation.

Additional information

Funding

The authors are grateful to the University of South Africa for their financial contribution towards completing this research.