[A-OS12] Physical, biogeochemical, and ecological processes and variability in the Indian Ocean

[AOS12-06] Distribution and movement of microplastics in the Indian Ocean

*Yukio Masumoto¹ (1.Graduate School of Science, The University of Tokyo)

Considering that one of the largest microplastic source regions is located in the maritime continent between the Pacific and Indian Oceans and that the Indonesian throughflow is passing through the maritime continent toward the Indian Ocean, much of microplastics injected in the region would be expected to flow into the Indian Ocean. However, details on their distributions and movements within the Indian Ocean have not been investigated. Using outputs of a high-resolution ocean general circulation model (OFES), particle tracking calculations are conducted to determine horizontal distribution of the microplastics in the Indian Ocean and to quantify how much of the microplastics flow into the Indian Ocean from the maritime continent. Most of the microplastics are accumulated within the subtropical gyre in the southern hemisphere. Although microplastics have been observed in the Southern Oceans near Antarctica, this study suggests that it is difficult to reach far south near Antarctica by the simple dispersion of the materials flowing at the sea surface. Further analysis on a role of three-dimensional circulations to transport microplastics farther south across the Antarctic Circumpolar Currents would be required.