Changes in (micro and macro) plastic pollution in the sediment of three sandy beaches in the Eastern Mediterranean Sea, in relation to seasonality, beach use and granulometry.

Smaller sized plastics (microplastics or MPs <5 mm) are ubiquitous in nature and have been found to interact in diverse ways with most biotic and abiotic systems globally. Most MPs in the seas have a land-based source, however, little is known about how the transfer occurs. In our study, we used three sandy beaches to describe the process of how MPs travel from accumulation points at the backshore of the beach to the sea, and vice versa. MPs differed significantly in all three beaches (both in quantitative and qualitative terms) between the summer and the winter samplings. During the summer, heavy MPs are the majority, while during the winter, lightweight microplastics are predominant, and the ratio of heavy per lightweight MPs is affected by the sediment median diameter after the summer sampling. Macroplastics follow a similar pattern to MPs and appear to provide a source of MPs for the sea.