Hinata Hirofumi, Mori Keita, Ohno Kazuki, Miyao Yasuyuki, Kataoka Tomoya
Department of Civil and Environmental Engineering, Faculty of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
Department of Civil and Environmental Engineering, Faculty of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
Mar Pollut Bull. 2017 Sep 15;122(1-2):17-26. doi: 10.1016/j.marpolbul.2017.05.012. Epub 2017 Jun 16.
Residence times of microplastics were estimated based on the dependence of meso- and macrolitter residence times on their upward terminal velocities (UTVs) in the ocean obtained by one- and two-year mark-recapture experiments conducted on Wadahama Beach, Nii-jima Island, Japan. A significant linear relationship between the residence time and UTV was found in the velocity range of about 0.3-0.9ms, while there was no significant difference between the residence times obtained in the velocity range of about 0.9-1.4ms. This dependence on the UTV would reflect the uprush-backwash response of the target items to swash waves on the beach. By extrapolating the linear relationship down to the velocity range of microplastics, the residence times of microplastics and the 1D onshore-offshore diffusion coefficients were inferred, and are one to two orders of magnitude greater than the coefficients of the macroplastics.
微塑料的停留时间是根据中、大型垃圾停留时间与其在海洋中的向上终端速度（UTV）的相关性来估算的，该相关性是通过在日本新岛和玉滨海滩进行的为期一年和两年的标记重捕实验获得的。在约0.3-0.9m/s的速度范围内，停留时间与UTV之间存在显著的线性关系，而在约0.9-1.4m/s的速度范围内获得的停留时间之间没有显著差异。这种对UTV的依赖性将反映目标物品对海滩上冲激波的涨潮-退潮响应。通过将线性关系外推到微塑料的速度范围，推断出微塑料的停留时间和一维岸上岸下扩散系数，其比大型塑料的系数大一个到两个数量级。
