Author(s): A. H. M. Enamul Kabir; Masahiko Sekine; Tsuyoshi Imai; Koichi Yamamoto
Linked Author(s):
Keywords: Japan; Microplastics; Marine environment; River; Transportation
Abstract: Marine microplastics pollution has been a global emerging threat. Rivers have been identified as the major transporting pathways of microplastics from land sources into marine environments. This study investigated microplastics in the two rivers i.e. Awano River (AR) and Majime River (MR) which are flowing into the Sea of Japan (SJ) and the Seto Inland Sea (SIS) respectively in the Yamaguchi prefecture, Japan. River surface water samples were collected from the selected stations (n=12) from the upstream to downstream directions. Filtration, wet peroxidation, and density separation methods were applied to extract microplastics. Polymers were identified through ATR-FTIR analysis. The mean microplastics abundance results (AR− 131±17.12 n/L, MR− 272.5±299.15 n/L) revealed high-level pollution. Characterization demonstrated that small microplastics (<1 mm) in sizes, fibers and fragments in shapes were predominant characteristics for these rivers. Polymer identification results revealed that polyethylene, polypropylene, vinylon and polyethylene terephthalate were the major polymers. Both the point and non-point sources could release MPs. The estimated loadings (AR- 92.36 billion particles per day and MR- 3.48 billion particles per day by numbers) into the SJ and SIS marine environments represented the fate of large quantities Japan land originated MPs as well as same major polymer types in these rivers and marine environments indicated that the Japan land contributed to microplastics pollution largely. Overall, the river freshwater systems were found to be highly MPs polluted and the prominent MPs transporting pathways from land-sources to the marine environments.
Year: 2020