[M-IS09] Ocean Plastics, an earth science perspective

[MIS09-P09] Temporal changes in fine-size microplastic deposition rates reconstructed from Beppu Bay sediments and the controlling factors

*Michinobu Kuwae¹, Kazushi Kinugawa², Hirofumi Hinata³ (1.Center for Marine Environmental Studies, 2.Super Science Course, Ehime University, 3.Faculty of Engineering, Ehime University)

Keywords:fine-seze microplastic, deposition rates, Beppu Bay, oleo-extraction

It has been unclear when marine microplastic (MP) pollution, which might induce the sixth mass extinction of organisms in Earth's history, will exceed a planetary boundary. In particular, the coastal ocean, which is close to its source and severely polluted in MP, is likely to be the ideal area for setting the planetary boundary. The key to setting the planetary boundary is to reconstruct records of temporal changes in the deposition rates of fine-size MP(<300 µm) to the seafloor, which determines the concentration of fine MP (<300 µm) in the ocean surface layer, and to understand the causes of these changes. In this presentation, we will report on the reconstruction of the fine-size MP deposition rate record for the past 70 years using Beppu Bay core samples and its relationship with environmental factors. We also discuss how quantitative accuracy has been improved by new methods of fine-size MP extraction from sediments.