Comparison the Geochemical Background, Threshold and Anomaly with Pollution Indices in the Assessment of Soil Pollution: Al-Hawija, North of Iraq Case Study

The geochemical background, threshold and anomaly values are compared with pollution indices (Enrichment Factor, Contamination Factor, Geo-accumulation index and Pollution Load Index) in soil collected from Al-Hawija area. The main target is to clarify the differences between the real geochemical background values of heavy metals (Cd, Pb, Co, Cr, Ni, V, Cu, Zn, Mo, As, Th and U) and the results of pollution indices. The results showed that the Contamination Factor is often almost consistent with the geochemical background, the Enrichment Factor indicated a low to moderate contamination soil, Geo-accumulation index indicated unpolluted to moderately polluted soil and Pollution Load Index indicated perfection to deterioration soil. The real geochemical background showed a natural distribution of most heavy metals with anomaly of some other. This anomalies didn't attributed to the pollution, but rather reflect the source from which soil has been derived. Pollution indices depend almost entirely on the global reference averages, and don't take the soil origin into account. Consequently, they gave results differ than the geochemical background. The pollution assessment of the heavy metals using EF is more consistent with the geochemical background, but there is high variation when compared the geochemical background to the CF, I-geo and PLI indices.