Factors influencing the vertical distribution of microplastics in the beach sediments around the Ras Rakan Island, Qatar

Abstract

Microplastic (MP) pollution is an emerging environmental problem, particularly in the marine environment, and nations are concerned about this issue. In this study, an attempt has been made to investigate the vertical distribution of MPs present in the beach sediments around the Ras Rakan Island of Qatar. Sampling was conducted at 9 locations, vertically to a depth of 30 cm with an interval of 5 cm. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy was used to chemically identify the subsets of MPs as polyethylene (PE), polypropylene (PP), polyamide (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polystyrene (EPS). The counts of MPs were found to be higher in the western and northern parts of the island. The vertical distribution of MPs ranged from 0 to 665 particles/kilogram with maximum abundance at the surface layer (0-5 cm). Pellets were the dominant type of MPs in the surface sediments, whereas fibers were dominant in the bottom sediments. The prevailing winds, waves, tides, and currents are the forces responsible for the distribution and transport of MPs from offshore to the island and further to vertical re-distribution as time progresses. The level of MP pollution along the coast of Ras Rakan Island was higher than that found on the coast of mainland Qatar. Thus, informing that remote islands should also be considered for MP pollution monitoring programs to assess the risk associated with MP on the biota.