Application of energy dispersive X-ray fluorescence, γ-ray spectrometry and multivariate statistical approach for the classification of soil/sand from Douala – Cameroon

Highlights: • EDXRF for elemental characterization of soil and sand. • Use of gamma-ray spectrometry technic for natural radioactivity assessment. • PCA statistic analysis to establish correlations between radiation parameters. • Linear Pearson, Kendall's tau, and Spearman's rho coefficients (²²⁶Ra ←agree.→ ²³⁸U) • Pioneer work: origin and geological provenience of the investigated area settled. The distribution of natural radionuclides in sediments from Douala, Cameroon has been carried out based on X- and γ-ray spectrometry. Radiological health parameters were evaluated and found to be lower than the internationally approved values for actions. Soil elemental characterization and differentiation displayed the concentration of major elements. In addition, the principal component analysis (PCA) established correlations between different parameters of the study by calculating linear Pearson, Kendall's tau, Spearman's rho correlation coefficients, and cumulative probabilities. The total average concentrations of radionuclides ²³⁵U, ²³²Th, ²²⁶Ra, and ⁴⁰K were 3.2, 53.1, 33.4, and 301.2 Bq/kg, respectively. The principal component analysis based on linear Pearson, Kendall's tau, Spearman's rho correlation coefficients, and cumulative probabilities calculations displays a strong correlation coefficient only between Ra-226 and U-235. The combination of spectrometry, PCA results, and comparison with previous studies highlighted the main characteristics of the investigated area to be illustrative dregs from the Continental margin. As a pioneering study using both spectrometric and PCA methods in Douala, the method was proved to be useful, and the results would be set as a database for future investigations.