Spatial distribution and evaluation of heavy metals in surface sediments of the Al-Najaf sea depression reservoir, Iraq

The Al-Najaf sea is a natural groundwater depending depression reservoir. The increase in uncontrolled dumping of solid waste in nearby areas and the use of sewage and animal manure as agricultural enhancing agents raise the fear of threatening the natural life in this lake by increasing metal concentrations in sediments. Forty-eight samples of sediments were collected, and the concentrations of eight metals (Fe, Zn, Cr, Mn, Co, Pb, Cd, and Ni) were measured in each sample. Five pollution indices (contamination factor, degree of contamination, pollution load index, enrichment factor and geo - accumulation index) were calculated. Spatial distributions with the pollution indices were studied to detect the specific metals that may contaminate the sediments and their probable source from the pattern of their distribution. The study revealed that, for most metals, concentrations at the lake shore were higher than those in the interior of the lake. Moreover, all the pollution indices were higher than the critical value on shores and slightly less than the critical level inside the lake, which means that the use of spatial distribution of metals in combination with pollution indices are beneficial in the detection of metal polluted sediments and their possible sources from their transmission patterns. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University.