Determination of local background and baseline values of elements within the soils of the Birimian Terrain of the Wassa Area of Southwest Ghana

Abstract

This study establishes the local background and baseline values of elements in surface soils in Wassa area underlain by Birimian rocks using probability Q–Q plots. In this study, a total of 2868 soil samples were collected. The chemical elements in these samples were analysed by XRF technique. The results from the analysis were processed following Papastergios and Karim methods that normalized and transformed the data after which a best of fit is estimated to determine the background and baseline values. The method excludes the outliers at the extremities from the transformed data until the distribution follows a straight line. The method yielded the following background values in this study: 6.41 mg/kg for As, 52.55 mg.kg for Cr, 9.89 mg/kg for Pb, 10.21 mg/kg for Co and 17.18 mg/kg for Ni. The calculated baseline values were also 13.2 mg/kg, 80.7 mg/kg, 6.7 mg/kg, 6.4 mg/kg and 8.7 mg/kg for As, Cr, Pb, Co and Ni, respectively. The departure between the locally calculated background and baseline values of elements relative to worldwide accepted background and baseline values suggests the relevance to conduct such studies for the various geological provinces in the country as a vital step to properly and effectively manage and sustain the environment against environmental health diseases.

Keywords

• geochemistry
• background
• baseline
• environment
• surface soil
• ghana