Turkish Journal of Earth Sciences




The pollution history of aluminum (Al), chromium (Cr), cobalt (Co), lead (Pb), zinc (Zn), copper (Cu), and mercury (Hg) were evaluated using geochemical and sedimentological properties of two sediment cores. The MD22A contained a mass-flow unit and two coccolith units. The upper coccolith was characterized by high organic matter, but it was relatively depleted in terms of all studied elements, suggesting dilution by high inorganic carbon. In the mass-flow unit, the relatively high Cr, Co, Zn, and Hg levels suggested additional contamination sources from the Kocadere Stream and Kocasu River. The ranges of Al, Cr, Co, Cu, Hg, Pb, and Zn concentrations in mg kg-1 in all core sediment samples were 3510-45840 (Al), 35.7-216.6 (Cr), 3.5-38.1 (Co), 4.5-57.6 (Cu), 17.2- 187.2 (Zn), 8.9-71.8 (Pb), and 0.0-0.2 (Hg), respectively. The index of geoaccumulation (Igeo), enrichment factor (EF), contamination factor (CF), pollution load index (PLI), and ecological risk index (RI) were used to assess the contamination statuses of the samples. The MD22A core sediments contained more enriched trace elements than the MD89A core sediments. According to EF and Igeo, the sediments had moderate enrichment with Cr, Cu, Co, Pb, and Zn and were moderately contaminated with Cr, Co, Zn, Pb, and Hg. RI showed a moderate to high potential ecological risk for the presence of trace elements in the study area. The principal component analysis (PCA) results strongly suggested that the pollution (Cr, Co, Cu, Zn, Pb, and Hg) was mainly caused by anthropogenic activities around the region and transported to the eastern and southern coast of the gulf by the Kocasu River and the Karsak Creek. The upper part of the core in the Gulf of Gemlik has been significantly polluted with Cr, Co, Hg, and Zn since 1930.

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