Microplastics in the Persian Gulf

Background: Microplastics, as emerging and persistent pollutants, are ubiquitous in different environmental compartments and could be considered an ecological threat to wildlife and humans. Materials and Methods: In the present review article, the existing studies on the presence of microplastics in water, sediments, and aquatic organisms of the Persian Gulf were reviewed with regard to different sampling techniques, samples preparation, and identification methods.  Results: The results indicated that the contributions of various countries to microplastics pollution of the Persian Gulf were different. The findings from the Iranian side of the Persian Gulf (especially for coastal sediments) showed higher pollution than its Arabian side. Blue and black fibers were the most predominant types of microplastics in the Persian Gulf. Based on the results, low density microplastics were more dominant in the water column, while high-density plastics were mostly found in sediments. The predominant types of microplastics in marine organisms were related to their habitats. Conclusion: Microplastics contamination is a severe threat to the Persian Gulf’s environment. However, the lack of harmonized procedure for microplastics sampling, preparation, analysis, and report makes the comparison of different studies challenging. For instance, four studies reported the level of microplastics in seawater of the Persian Gulf with three different units. Hence, we suggest all studies use the same methodologies in the Persian Gulf to increase the comparability of the results.