X-ray Fluorescence (XRF) Analysis of Soil Heavy Metal Pollution from an Industrial Area in Kumasi, Ghana

Abstract

Knowledge of soil heavy metal concentration is very important for assessing the purity and quality of the soil in an environment. The concentrations of nine heavy metals (NHM), Zn, Pb, Cr, Cu, Co, Ni, Cd, Hg, and As, from the near-surface soils (∼ 0–15 cm) from an industrial cluster in Kumasi, Ghana, were qualitatively and quantitatively measured and analyzed using X-ray fluorescence (XRF) spectroscopy analysis. The sources of these NHM were mainly anthropogenic as a result of the indiscriminate industrial waste disposal. In all, a total of about 100 soil samples were taken from six sampling sites, four of which were industrial and the remaining two residential. Forty soil samples out of the total number were carefully selected for elemental analyses and the mean heavy metal concentrations were calculated using statistical methods. The results from locations of high industrial impact showed that the mean concentrations of the NHM present in the soil were in the order of Zn (189.2−908.6 mgkg⁻¹), Pb (133.7−571.3 mgkg⁻¹), Cr (91.3−545.8 mgkg⁻¹), Cu (62.9−334.6 mgkg⁻¹), Co (38.6−81.9 mgkg⁻¹), Ni (12.4−30.9 mgkg⁻¹), Cd (6.9−13.2 mgkg⁻¹), Hg (5.5−10.4 mg kg⁻¹), and As (2.3−18.6 mgkg⁻¹). Apart from Ni and As, all the heavy metals recorded concentrations that ranged from 10−900% higher than their respective threshold limit values (TLVs). Heavy metal concentrations from the residential sites were comparatively far lower with only Cr, Cd, and Hg registering concentrations between 65−250% above their TLVs. The cluster with its residential communities is at a serious risk of soil heavy metal toxicity and awareness to this needs to be created as such.

Keywords:

• Heavy metals
• X-ray fluorescence (XRF)
• soil pollution
• soil sample
• threshold limit values (TLVs)

Acknowledgement

The research was partly supported by the Geochemistry and Laboratories at Geological Survey Department, Accra, Ghana. The authors wish to acknowledge the invaluable help rendered by Mr. Edwin Bawa (Physics Department Laboratory, KNUST), Mr. Emmanuel Afum (Geochemistry and Laboratory, Geological Survey Department., Accra), and Mr. Gilbert (Geotechnical Laboratory, Civil Engineering Department., KNUST) for assisting in the laboratory work.