Geochronology and sources of heavy metal pollution in sediments of Istanbul Strait (Bosporus) outlet area, SW Black Sea, Turkey

• Published in: Chemosphere (Oxford) 2018-08, Vol.205, p.387-395
• Main Authors: Sarı, Erol, Çağatay, M. Namık, Acar, Dursun, Belivermiş, Murat, Kılıç, Önder, Arslan, Tuğçe Nagihan, Tutay, Ali, Kurt, Mehmet Ali, Sezer, Narin
• Format: Article
• Language: English
• Subjects: Black Sea; Cesium Radioisotopes - analysis; Environmental Monitoring - methods; Environmental Pollution - analysis; Geologic Sediments - chemistry; Heavy metal pollution; Lead Radioisotopes - analysis; Marine sediments; Metals, Heavy - analysis; Radionuclide dating; Rivers; Sedimentation rate; Turkey; Water Pollutants, Chemical - analysis
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2018.04.096

Geochemical and sedimentological analyses and radionuclide (210Pb and 137Cs) dating of three cores from the Bosporus outlet area of the Black Sea, north of Istanbul, were conducted to assess the sources and history of heavy metal pollution. The sedimentary succession in the shelf core KD12-01 consists mainly of clay (49–80%) and silt (15–41%). Radionuclide dating of the core indicates that it consists of old sediments that are uncontaminated with heavy metals. In contrast, cores KD12-04 and KD12-07 recovered from −350 m and −304 mm in the upper slope area represent sediments consisting of silt and clay that were deposited since at least the last 120 years and 60 years, respectively. The latter core contains two mass-flow units represented by relatively old sedimentary material according to the low 210Pb activity and relatively low heavy metal contents. The upper 40 and 48 cm of cores KD 12-04 and KD 12-07 represent sediments deposited since 1970s and 1980s that are significantly polluted with Cu, Ni, Zn, Mo, Pb and Cr, Cu, Co, Ni, Mo, Pb, Zn, respectively. However, high Pb and Cr concentrations with high TOC contents date back to early part of the 20th century in core KD 12-04. The geochemical data, together with the high 137Cs concentrations of the contaminated sediments, strongly suggest that the pollution is mainly delivered to the western and north western Black Sea by the large European rivers, from there transported to the study area by the rim current, and deposited in the sediments under anoxic conditions. •Study area is affected by pollutant inputs from the large European rivers.•High resolution metal, sedimentological and radionuclide analyses of three cores.•Timing of heavy metal and organic pollution in the area.•Assessment of the sources of metals, their transport and deposition in sediments under anoxic waters.