English abstract
Plastics and particularly microplastics are entering our oceans at an increasing rate. These microparticles enter food chains, disrupt reproductive cycles and are ingested by marine animals as mistaken food. A few studies on Oman beaches documented a dominance of plastic debris, but the occurrence of microplastics on the Sultanate beaches remains undocumented. Thus, the foremost objectives of this study were to evaluate the scale of the microplastic problem in the region and locally and to develop indicators to assess the prevalence of microplastic in the marine environment. This study reports for the first time, the presence, concentration, type and size of microplastics in Oman beach environment. It also proposes a standard and inexpensive protocol for the sampling, extraction and analysis of microplastics from sediment of the coastal areas. Biological and organic matters were removed from the sediment in a pre-treatment using sodium hypochlorite. Microplastics were then separated from the sediment by floatation using a saturated NaCl solution. Microplastic particles were then counted and sized on samples collected from 8 beaches spanning 200 km of coastline.Synthetic polymers were identified using (FT-IR) spectrometry.Microplastic particles were detected in all 8 beaches and subdivided into three categories: fragments, pellets and fibers. In term of numbers the most contaminated area was Barka with an average concentration of 50±14.1 particles/kg of sediment) while in term of weight, Al-Qurum was the most polluted area with average weight of 3.7±1.6 g/kg of sediment. The most abundant polymers were polyethylene and polypropylene, in particular in the form of industrial pellets. The presence of microplastics in sediments appear related to on-going disposal practice from beach users, industries and recreational activities along with accidental or intentional discharge from ships, particularly near industrial harbors (Sohar and Qurum). This beach-focused study should be extended geographically to include marine protected area (MPAs), industrial estates such as Raysut, Sohar, Al-Duqum, islands such as Al-Halanyyat and Masirah. In terms of ecosystem, it should be extended (with appropriate changes in methodology) to the surface of the sea. In addition, investigation of microplastics particles could be extended to cover risks of contamination of human consumed marine organisms.
