Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Modeling transport of microplastics in enclosed coastal waters: A case study in the Fethiye Inner Bay Asli Numanoglu Genc a,1, ⁎ , Nilufer Vural b,2 , Lale Balas c a Civil Engineering Department, TED University, Ziya Gökalp Street, No: 47-48 06420, Kolej, Çankaya, Ankara, Turkey b Chemical Engineering Department, Ankara University, Dögol Street 06100, Tandoğan, Ankara, Turkey c Civil Engineering Department, Gazi University, Celal Bayar Avenue, 06570, Maltepe, Ankara, Turkey ARTICLEINFO Keywords: Microplastic transport Enclosed waters Numerical modeling HYDROTAM-3D Fethiye Bay ABSTRACT In this study, transport and possible accumulation of microplastic marine litter in enclosed coastal waters are modeled numerically. The model is applied to the Fethiye Inner Bay, located in Fethiye-Göcek Specially Protected Area. In modeling studies, three dimensional coastal hydrodynamics, transport and water quality numerical model HYDROTAM-3D was used. The current climate was prepared by modeling long-term circula- tion patterns due to wind, wave and density stratifcations. Following the hydrodynamic studies, the advection anddifusionof3mmsizepolystyreneparticlesbythecoastalcurrentsinthesurfacewatersofFethiyeInnerBay were simulated. The coastal regions where the microplastic pollution will be concentrated and transported were determined by the modeling scenarios. It has been found that microplastic accumulation is expected in the southwest and east coastal waters of the Fethiye Inner Bay. The results of the model will contribute to the databases for sustainable protection of the marine environments. 1. Introduction One of the most important pollution aspects in the oceans and seas oftheWorldistheexistenceofplasticlitter.Intheoceans,75%oflitter is plastic (Galgani and Paul-Pont, 2015). It has been shown that plastic litterexistsattheseasurface,seawatercolumnandtheseabottomfrom macro to micro size. The adverse efects of plastic litter on the sea fauna,foodchainandhumanhealthhavealsobeenstudied(Friasetal., 2014; Galloway, 2015; Koelmans et al., 2015). Swallowing of plastic litter causes the death of marine life. There is evidence that micro- plastics are consumed at the bottom of the food chain and therefore transferred to the upper part of the food chain (Farrell and Nelson, 2013; Critchell and Lambrechts, 2016). The Mediterranean Sea has a high concentration of plastic litter where83%ofthe foatinglitterisplastic(Lebretonetal.,2012; Galgani etal.,2013; Cozaretal.,2015).However,thereisnotmuchdataonthe distribution, type, amount and source of marine litter. Most of the studies focus on the plastic litter at the beaches and sea bottom (Suaria and Aliani, 2014; Pasquini et al., 2016; Ruiz-Orejon et al., 2016). For the regional seas, there are only few signifcant studies (Suaria and Aliani, 2014). Tubau et al. (2015) have identifed that 73% of marine litter is plastic between the depths of 140–1731 m. in the underwater canyons at the ofshore of Genova and Lyon. Collignon et al. (2014),in theirstudy,whichfocusesonmicroandmesoplastics,haveshownthat, 54% of the plastics in the surface waters are microplastics ranging be- tween 2 and 5 mm in the Calvi Bay of Corsica. Vianello et al. (2013) studied the microplastics in the sediments of a tidal area in the Venice Lagoon and found that the most common microplastics are poly- ethylene and polypropylene. SuariaandAliani(2014) haveshownthat, 93% of the surface marine litter in the middle and west Mediterranean is plastics with Adriatic Sea having the most concentration. Koutsodendris et al. (2008) identifed that 56% of marine litter is plastic in the East Mediterranean. Ruiz-Orejon et al. (2016) have sam- pledthefoatingmarinelitterintheSardiniacoast,theSiciliacoast,the Adriatic Sea and the Ion Sea. They concluded that 97% of foating marine litter is plastic. The level of plastic pollution in marine waters has been shown in many studies and this resulted in international action plans. EU Marine Strategy Framework Directive (EU MSFD, 2008/56/EC) aims member countries to reach ‘Good Environmental Status (GES)’ by 2020. Additionally, at the 18th meeting of Contracting Parties to the Barcelona Convention for the Protection of the Marine Environment https://doi.org/10.1016/j.marpolbul.2019.110747 Received 14 October 2019; Received in revised form 16 November 2019; Accepted 16 November 2019 ⁎ Corresponding author. E-mail addresses: asli.genc@tedu.edu.tr (A.N. Genc), nilufer.vural@science.ankara.edu.tr (N. Vural), lalebal@gazi.edu.tr (L. Balas). 1 Aslı Numanoğlu Genç 2 Nilüfer Marine Pollution Bulletin xxx (xxxx) xxxx 0025-326X/ © 2019 Elsevier Ltd. All rights reserved. Please cite this article as: Asli Numanoglu Genc, Nilufer Vural and Lale Balas, Marine Pollution Bulletin, https://doi.org/10.1016/j.marpolbul.2019.110747