Metal contamination in surficial sediments of Edremit Bay (Aegean Sea): Spatial distribution, source identification and ecological risk assessment

Seasonal and spatial distributions of metals in surficial sediments of Edremit Bay (Aegean Sea, Turkey) were investigated to determine contamination status, possible sources and ecological risks in the study area. Seasonal (autumn and spring) surface sediment samples were collected in 2015 with a box-corer from 14 stations. Metal concentrations (Hg, Cd, Pb, Cr, Cu, Mn, Zn, Fe, Al), grain size distributions and organic carbon levels were determined in samples. Metal levels were analyzed with flame (Pb, Cr, Cu, Mn, Zn, Fe, Al), cold-vapor (for Hg) and graphite furnace (for Cd) atomic absorption spectrometer after microwave digestion. Ranges of metal concentrations in Edremit Bay sediments were Hg: 0.03-017, Cd: 0.10-0.27, Pb: 5.32-47, Cr: 66-219, Cu: 13-57, Mn: 382-729, Zn: 66-154, Fe: 18685-50539 and Al: 10244-82819 mg/kg dry weight. Enrichment factor, geo-accumulation index, and contamination factor values were calculated, and the results indicated the presence of moderate Pb, Cr and Zn pollution in the sediments. According to sediment quality guidelines (threshold and probable effect levels), sediments were moderately to heavily polluted with Cr and Mn, and no potential harmful effects of Cd, Hg, Zn, Pb and Cu were found for aquatic organisms. Statistical analyses and risk assessments suggested that natural processes (i.e. streams, springs and rain run-offs) and anthropogenic inputs (i.e. mines, agricultural activities and domestic effluents) may have contributed to the metal levels in surficial sediments of Edremit Bay. (C) 2020 Elsevier B.V. All rights reserved