[M-IS19] 地球科学としての海洋プラスチック

[MIS19-05] TARA-JAMBIO Joint Microplastic Survey: Distribution, Flux and Plastisphere of Microplastics in Japanese Coastal Areas.

*Jonathan Josh Ramtahal^1,2、Kugako Sugimoto¹、Tara Jambio Consortium^4,3、Yumiko Patouillet⁴、Sylvain Agostini¹ (1.Shimoda Marine Research Center, University of Tsukuba、2.Graduate School of Science and Technology, University of Tsukuba、3.Japan Association of Marine Biology、4.Tara Ocean Fondation, Japan)

キーワード：microplastics, plastisphere, sediment, surface water, public awareness, Japan coasts

Tara Océan Fondation (https://fondationtaraocean.org) is dedicated to the Ocean through collaborative scientific expeditions, raising public awareness, mobilizing policy makers and stakeholders at the highest levels, and providing global access to the latest scientific knowledge concerning our Ocean. Since 2020, TARA-JAMBIO Joint Microplastic Survey is a combined effort of Tara Ocean Foundation and Japanese Association for Marine Biology to investigate the status of microplastic pollution in coastal areas throughout Japan. Microplastics cannot be fully retrieved from the ocean, due to the small size of particles and may cause damage to marine ecosystems and organisms. The synthetic nature of microplastics contribute to their slow rate of degradation, low rate of mineralization, and long-term persistence in the marine environment. However, there is a lack of scientific knowledge on the sources, fluxes, and distribution of microplastic in the marine matrices. As such, the Joint Microplastic Survey has two aims, the first is to assess microplastic pollution in surface water and sediment of Japanese coasts, the fluxes of microplastic from rivers and bays and to characterize the bacterial communities on plastic fragments (termed ‘the Plastiphere’). Secondly the project aims to raise awareness of plastic pollution and encourage a reduction in the use of plastics, and to inform on threats to the ocean caused by anthropogenic activity. Sampling was conducted at 10 marine stations belonging to the JAMBIO network in West and North Japan (https://www.jambio.org). A Neuston net was used to sample surface waters, while a Smith McIntyre Grab was used for sediment collection. Microplastics (300-5000 µm) were extracted using density separation (NaCl) followed by wet peroxide oxidation (H₂O₂) and sorted using UV-microscopy. Samples collected for the ‘plastisphere’ study were collected under microscope immediately after each sampling event and processed for DNA extraction using DNeasy PowerSoil® Pro Kit, Qiagen® and downstream analysis. To assess the horizontal fluxes, sampling was conducted at a river mouth, within a bay and outside a bay at each marine station. To date, plastic fragments were found in all surface water and sediment samples that have been processed. The high concentrations recorded in some samples confirmed the prevalence and omnipresence of microplastics in Japanese waters but also highlights the large temporal and spatial variations in concentration. Community-based outreach and collaboration with local artists was implemented to facilitate public awareness and engagement during this project. At each location local artist joined the sampling and produced a piece of art that will be publicly displayed at the Setouchi Triennale 2022. Interactive events were held for the local communities, which included beach cleaning, and educational talks about plastic pollution and everyday solutions to reduce plastic use.