Abundance, composition, and distribution of microplastics larger than 20 mm in sand beaches of South Korea * Soeun Eo a, b , Sang Hee Hong a, b , Young Kyoung Song a, b , Jongsu Lee c , Jongmyoung Lee c , Won Joon Shim a, b, * a Oil and POPs Research Group, Korea Institute of Ocean Science and Technology, Geoje, 53201, Republic of Korea b Department of Marine Environmental Sciences, Korea University of Science and Technology, Daejeon, 34113, Republic of Korea c Korea Marine Litter Institute, Our Sea of East Asia Network, Toyeong, 53013, Republic of Korea article info Article history: Received 11 November 2017 Received in revised form 25 March 2018 Accepted 26 March 2018 Keywords: Microplastics Abundance Distribution Marine plastic debris abstract To support microplastic management, the abundance, composition, and spatial distribution of micro- plastics on a national scale must be known. Hence, we studied the baseline level of microplastic pollution at 20 sandy beaches along the South Korean coast. All microplastic particles extracted from the sand samples were identified down to 20 mm in size using Fourier transform infrared spectroscopy. The abundances of large microplastics (L-MPs; 1e5 mm) and small microplastics (S-MPs; 0.02e1 mm) were in the range of 0e2088 n/m 2 and 1400e62800 n/m 2 , respectively. Maximum microplastic abundance was in the size range of 100e150 mm, and particles smaller than 300 mm accounted for 81% of the total abundance. Expanded polystyrene (EPS) accounted for 95% of L-MPs, whereas S-MPs were predomi- nantly composed of polyethylene (49%) and polypropylene (38%). The spatial distribution of L-MPs, excluding EPS, was significantly related to population, precipitation, proximity to a river mouth and abundance of macroplastic debris on beach. However, there were no relationships between S-MPs and other environmental and source-related factors, except for macroplastic debris and L-MPs excluding EPS. These results imply that S-MPs are mainly produced on beaches by weathering, whereas L-MPs other than EPS are mainly introduced from land-based sources and are also partly produced on beaches. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Microplastics are ubiquitous in the marine environment (Shim and Thompson, 2015). Contamination levels of microplastics in various marine compartments have been reported worldwide (Lusher et al., 2015). Sandy beaches are particularly known to accumulate both macro- and microplastics (Lee et al., 2015). Stranding of floating plastic debris from seawater and litter from land contribute to the accumulation of plastic debris on beaches. Moreover, weathering of plastic litter on beaches can produce fragmented microplastics (Corcoran et al., 2009). Beach environ- ments provide relatively good natural weathering conditions to plastic debris compared to the sea surface and seafloor in terms of the high availability of ultraviolet light, oxygen, mechanical forces, and high temperatures (Andrady, 2011; Song et al., 2017). In addi- tion, beach sampling efforts and costs are relatively small compared to sea surface and seafloor sample collection. Many beach investigations have focused on large microplastics (L-MPs, 1e5 mm), including macroplastic debris larger than 5 mm (Ivar do Sul et al., 2009; Jayasiri et al., 2013; Lee et al., 2013; Baztan et al., 2014). Information on small microplastics (S-MPs, <1 mm) is limited because their analysis requires more time and effort than does that of L-MPs (Browne et al., 2010; Costa et al., 2010; Carson et al., 2011; Martins and Sobral, 2011; Hidalgo-Ruz et al., 2012; Kim et al., 2015; Song et al., 2015). The potential for microplastic ingestion by marine organisms increases with decreasing micro- plastic size (Wright et al., 2013a). While the abundances of meso- plastics (5e25 mm) and L-MPs are strongly positively correlated on beaches (Lee et al., 2013), the relationship between L-MPs and S- MPs in beach environments has not been fully clarified. Stranded plastic litter can be fragmented into microplastics by weathering (Andrady, 2011), and small microplastics can be directly introduced into the ocean (Browne et al., 2011). Rivers are an important source * This paper has been recommended for acceptance by Maria Cristina Fossi. * Corresponding author. Oil and POPs Research Group, Korea Institute of Ocean Science and Technology, Geoje, 53201, Republic of Korea. E-mail address: wjshim@kiost.ac.kr (W.J. Shim). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol https://doi.org/10.1016/j.envpol.2018.03.096 0269-7491/© 2018 Elsevier Ltd. All rights reserved. Environmental Pollution 238 (2018) 894e902