Investigation of microplastic pollution in the Southern Caspian Sea Coastal Sediments

The presence of microplastics (less than 5 mm) in marine environments, owing to their persistence and risk imposed to marine communities has become a growing global concern. Considering the hazardous nature of microplastic particles to benthic communities and commercial species of the Caspian Sea, the study was conducted to investigate the distribution of microplastics in sediments of the southern shores of the Caspian Sea. Sediment samples were taken by a Van Ween grab as sampling sites located in Astara, Bandar Anzali, Kiashahr, Rudsar, Sari and Turkmen port during the winter 2018. Sari station with an average of (340±20 items/kg dry sediment) had the highest and Turkmen port station with (156.66±75.71 items/kg dry sediment) had the lowest microplastic frequency. The size of the microplastics varied from 0.2-9.2 mm and most of the microplastics found (35.54%) were 1-2 mm in size. The extracted microplastics were mainly filamentous although fragment microplastics and films were also observed. In the studied samples, high color diversity was observed and blue (63.85%) and brown (20.31%) had the highest frequency. Using ATR-FTIR analysis, 4 types of polymers including cellophane, polyethylene, polypropylene and polyvinyl acetate were identified. The most abundant microplastics identified were cellophane. This study is among very few studies on microplastic contamination in the sediments of the southern Caspian Sea and the obtained results vital for further studies.