Microplastic Pollution Along The Southeastern Black Sea

Within the scope of TUBITAK 118Y125 project, microplastic pollution was investigated at the coastal areas of the mouth of several rivers in the southeastern Black Sea, namely the rivers Karasu, Kizilirmak, Yesilirmak, Melet, Aksu, Degirmendere and Firtina. Here we present results of the first cruise that occurred during July 2019. At each station, samples were collected from surface waters with manta trawl, from several depths with Niskin bottles and from sediments with box core. Microplastics were characterized using optical microscopy, FT-IR and SEM/EDS in terms of size, morphology and chemistry. Surface microplastic concentration ranged between 1.783 and 40.03 par.m(-3) (0.178x10(6)-4x10(6) par. km(-2)). The primary shapes were fragments (49%), followed by films (31.3%), fibres (17.7%), foams (1.9%) and beads (0.1%). Twelve different colours of microplastics were detected in surface waters with the most common colour being white (34.3%), followed by transparent (28.9%) and blue (11.8%). The average size was calculated as 1.540 +/- 1.065 mm, 1.984 +/- 1.022 mm, 2.076 +/- 1.205 mm, 2.302 +/- 1.225 mm and 0.670 +/- 0.245 mm for fragments, films, fibres, foams and beads, respectively. Microplastic concentrations at subsurface depths, reached up to 20 par.l(-1). An increasing MP concentration with depth was observed. Microplastic concentrations in sediment varied from 74.1 to 1778.8 par.m(-2) (0.004-0.192 par.ml(-1)). The primary shapes in the sediment were fibres (66.4%), followed by fragments (19.9%), films (13.3%) and beads (0.4%), no foam was found. Ten different colours of microplastics were found in the sediment with blue being the most common colour (40.7%) followed by red (23.5%) and transparent (15.9%). The average size was calculated as 1.253 +/- 0.954 mm, 1.035 +/- 0.429 mm, 1.358 +/- 0.892 mm, and 0.079 mm for fibres, fragments, films, and beads, respectively. The FTIR analysis confirmed the presence of eight polymers in surface waters and tree polymers in the sediment samples. Polyethylene and polypropylene were the most common polymers both in sea surface and in sediment. Our results confirm that microplastics were present in all matrices (surface, water column and sediment) of the Black Sea. Project results will provide data on distribution, sources and effects of microplastics required to implement the "Marine Strategy Framework Directive".