Determination of the abundance and diversity of micro and macro plastics in some sandy beaches used for recreational purposes in Muğla province

The aim of this study was to evaluate the abundance and diversity of macro- and microplastics in sand samples collected from 8 differents beaches used for recreational purposes in Muğla province (Ölüdeniz Kumburnu Beach, Sarıgerme Beach, Iztuzu Beach, Icmeler Beach, Aktur Beach, Akyaka Beach, Bitez Beach and Yahşi Beach). To this aim sand samples were collected in 2 different seasons (summer and winter) from different stations along the 8 selected beaches and the abundance of micro and macro plastics were evaluated. Possible sources of micro and macro plastics were also investigated. Approximately 3 kg of sand samples were taken from the surface to ~ 3-4 cm depth using a quadrat of 50×50 cm2, and transferred to the laboratory. Extraction processes of micro and macro plastics from sand samples were carried out according to international standards and microplastics were examined under a microscope and counted according to color, shape and size groups. Furthermore, the polymer types of the detected microplastics were determined by Attenuated Total Reflection – Fourier Transform Infrared Spectrometer (ATR-FTIR). According to the results, in the summer season the highest abundance of microplastics was determined at Ölüdeniz Kumburnu Beach (360 ± 237.66 particles kg-1 dw) whereas the highest abundance of macroplastic was found at Aktur Beach (11.80 ± 6.37 particles kg-1 dw). In the winter season, the maximum abundance of micro- and macroplastics was determined at Aktur Beach (358.33 ± 397.24 particles kg-1 dw for microplastics, 12.50 ± 16.01 particles kg-1 dw for macroplastics). By a total screen of determined microplastics, the most dominant category was found to be fibrils in terms of shape and blue in terms of color in both seasons. For macroplastics, fragments in terms of shape and white particles in terms of color were the highest ratio in both seasons. In terms of size, microplastics were examined in two different size groups, 0.1 µ - 1 mm and 1 mm - 5 mm, and microplastics in the 1 mm - 5 mm size range were more abundant in both sampling seasons. As a result of ATR-FTIR analyzes, the low density polyethylene (DYPE) and atactic polypropylene (aPP) types were found to be the most abundant in both seasons in the study area. The obtained data were mapped with Geographic Information System (GIS) and evaluated statistically. No statistical difference was found between the two seasons regardless of the station. However, significant differences were found between Ölüdeniz Kumburnu Beach and all the other beaches in the summer season in terms of microplastics abundance. In the winter season, significant differences were found between Aktur Beach and all the other beaches except Ölüdeniz Kumburnu Beach in terms of microplastics abundance. Furthermore, a positive and significant correlation was determined between the wind speed and the microplastic accumulations on the beaches in the winter season. The study area is an important tourist center away from highly populated cities, industrial areas and large commercial ports. In this context, the most important factors that may affect the microplastic pollution in this area may be the increasing population as a result of tourism activities in the summer period, the discharge waters of wastewater treatment plants, and the transportation by waves, wind and rivers.