Abstract The soil samples, gathered from twenty-four sites in Iraq, were analysed using X-Ray Fluorescence device (XRF) for the concentrations of the thirty trace elements (TEs), including Ti, Cu, Mn, Ni, Co, Cd, Mo, Pb, Cr, V, Zn, Ga, Ge, As, Se, Br, Rb, Y, Ag, Sr, Sb, Sn, I, Ba, W, Hg, Th, Bi, TI, and U, to evaluate their spatial distribution, sources, and pollution levels. Statistical methods of principal component analysis (PCA) and agglomerative hierarchical cluster analysis (AHCA) were used to identify pollution sources and clustering of stations, indicating that seven PCs account for > 90% of the variability in the TEs results. The PC1, accounting for 58.69% of the total variants (TV), showed a strong factor loading for Ti, Cr, Mn, Ni, Cu, Rb, Y, and Tl, indicating sources from rock weathering. It also had moderate loading of V, W, Pb, Th, and U, which are derived from natural and anthropogenic sources. The PC2 explains 12.84% of the TV and had strong loadings of As, Se, Br and moderate loadings for I, which indicates the natural factors and the effect of anthropogenic release of these elements into the soils. The PC3 explains 3.152% of TV and had a strong factor loading of Ba, which was due to the high concentration of Ba in sample 24 because of contamination with the drilling fluids that are used in the petroleum production processes in Basra oil fields located in the south of Iraq. The soil samples from the middle of Iraq stations 7, 8, and 9 and the soil samples from south of Iraq 17, 18, and 22 generally recorded higher levels of pollution by TEs. These areas are close to many contamination sources, such as Al-Dora crude oil refinery, Al-Dora and South Baghdad electrical power plants in the middle of Iraq and petroleum production and Al-Basra oil refineries in the south of Iraq. Agricultural practices and poultry farms also release TEs such as Cr, Co, Cd, Sb, Ba, Hg, and Bi into the soils of these areas. The result of the Enrichment Factor (EF) showed that most TEs had moderate EF values less than 5. On the other hand, the TEs showed high to extremely high EF were Cr, Co, As, Se, Br, Mo, Cd, Sb, I and Hg. The results of the Contamination Factor (CF) ranged from 0.01 to 176.19, and the TEs of Cr, Ni, Sn, W, and Bi showed considerable contamination levels in most samples. TI showed considerable contamination levels in all the samples, Co in 50% of the samples, and As, Br, Se and Sr in a few samples. While TEs showed very high contamination levels of Cr, Co, Ge, Se, Sr, Sb, I, Ba, W and Hg in a few samples. The Mo, Ag and Cd showed very high contamination levels in all samples and Bi in most samples. The elevated TE concentration has severe environmental consequences and affects plant and human life in the long run, for which remedial and preventive strategies need to be devised to prevent at-risk areas and populations.
Al-Gburi et al. (Mon,) studied this question.