Evaluation of Microplastics in Beach Sediments along the Coast of Dubai, U.A.E

Abstract

The unprecedented increase in consumption in conjunction with poor management of plastic waste have resulted in global contamination of both terrestrial and marine environments. Plastic debris undergoes fragmentation, resulting in the formation of microplastics, a synthetic polymers less than 5 mm in size. Significant amounts of microplastics have been globally observed in beach sediments. However, no studies have addressed microplastic contamination of marine sediments and/or coastal water in the United Arab Emirates. In this study, microplastic contamination in beach sediments of sixteen beaches along the Arabian Gulf coast in Dubai have been studied. Five samples of beach sediment were collected approximately from 1 cm below the surface from each beach along a 100 m stretch using a 0.5 m by 0.5 m, steel quadrant along the wrack lines. Density separation was used to extract microplastics from the sediment samples. The number of pieces of microplastics were identified under a 40X dissecting microscope and categorized by color and shape. Furthermore, microplastics polymer types were identified through FT-IR analysis. The results showed that the average weight of microplastic is 0.33 mg. g⁻¹ of sediment (or 953 mg.m⁻²) and the number of microplastic is 59.71 items.kg⁻¹ of sediment (or 165 items.m⁻²) in the study area. A total of 3366 pieces of microplastic were found in the 80 samples with 10 different colors; blue, red, green, yellow, black, white, grey, orange, pink, and transparent. The analysis showed that blue microplastics are more abundant in terms of numbers, while white ones are most abundant in terms of the number of microplastics per square meter (items.m⁻²) and number of microplastics per kg dry weight of sediment (items.kg⁻¹). Furthermore, four shapes of microplastics were identified including fiber (most dominant), string, pieces, and polystyrene spheres. FT-IR analysis was conducted to identify the polymer type of fibers and strings that were large enough to handle using forceps which were 1396 microplastics. 63.67% of the samples were identified to be polyethylene and 32.94% were found to be polypropylene. XRF analysis identified 14 heavy metals on the extracted microplastics including Cr, Ni, Cu, Zn, and Pb, which are classified as priority pollutants by EPA.