Assessment of heavy metal contamination in sediments of the Tigris River (Turkey) using pollution indices and multivariate statistical techniques

Heavy metal concentrations in sediment samples from the Tigris River were determined to evaluate the level of contamination. The highest concentrations of metals were found at the first site due to metallic wastewater discharges from copper mine plant. Sediment pollution assessment was carried out using contamination factor (CF), pollution load index (PLI), geoaccumulation index (Igeo) and enrichment factor (EF). The CF values for Co, Cu and Zn were >6 in sediments of the first site, which denotes a very high contamination by these metals. The PLIs indicated that all sites except the first site were moderately polluted. Cu, Co, Zn and Pb had the highest Igeo values, respectively. The mean EF values for all metals studied except Cr and Mn were >1.5 in the sediments of the Tigris River, suggesting anthropogenic impact on the metal levels in the river. The concentrations of Cr, Cu, Ni and Pb are likely to result in harmful effects on sediment-dwelling organisms which are expected to occur frequently based on the comparison with sediment quality guidelines. PCA/FA and cluster analysis suggest that As, Cd, Co, Cr, Cu, Mn, Ni and Zn are derived from the anthropogenic sources, particularly metallic discharges of the copper mine plant.