The pelagic microplastics detected in the Southern Ocean

With the support of the Environment Research and Technology Development Fund (ERTDF), the research team of the Kyushu University and the Tokyo University of Marine Science and Technology (TUMSAT) detected pelagic microplastics in the Southern Ocean. Their research paper was opened on the website of the journal "Marine Pollution Bulletin". This is the first peer-reviewed paper on pelagic microplastics in the Southern Ocean.

1. Background

   The mismanaged plastic waste drifting in the ocean and washing ashore on beaches is gradually degraded into tiny fragments because of exposure to ultraviolet radiation and mechanical erosion on beaches, and thereafter re-drifts into the ocean. In particular, plastic fragments smaller than 5 mm are referred to as "microplastics". Microplastics may act as transport vectors of chemical pollutants into the marine ecosystem, owing to the absorption of pollutants onto the plastic surface and the ingestion of tiny microplastics by marine organisms. The previous researches have shown that pelagic microplastics are detected in coastal waters around the world, marginal seas such as the Sea of Japan, the high seas such as the Pacific and Atlantic Oceans, and Arctic polar waters.

2. Results

   Supported by the Environment Research and Technology Development Fund (ERTDF) of the Ministry of the Environment, Japan, a field survey was conducted by the research team of the Kyushu University and the Tokyo University of Marine Science and Technology (TUMSAT) to investigate the marine pollution by microplastics, using a T/V Umitaka-maru, belonging to TUMSAT. As a result, 44 pieces of microplastics were detected at five stations in the Southern Ocean, and 38 of 44 were detected at two stations nearest to Antarctica. The largest total particle count (vertical integration of microplastic concentrations at depths), which was deducted using the seawater volume passing through the sampling net during the towing, and the wind speed/wave height measured on the vessel, was estimated to 286,000 pieces km^-2. This value was the same order of the magnitude reported in the North Pacific.

3. Publication of research paper

   With a title called "Microplastics in the Southern Ocean", this research was opened publicly on the website of the journal "Marine Pollution Bulletin". This is the first peer-reviewed paper on pelagic microplastics in the Southern Ocean.

（Left figure）

Observed total particle counts and schematic view of oceanic conditions in the Southern Ocean. The bars at the two stations nearest to Antarctica indicate the total particle counts, and their reference scales are shown in the upper left corner. Schematically shown are the positions of three oceanic fronts by the wavy lines, and the Antarctic Circumpolar Current by the arrows.

（Right figure）

Size distribution of plastics fragments in the Southern Ocean. The photographs (a), (b) and (c) are of microplastics collected in the Southern Ocean in the size ranges corresponding to the columns with the same letter at the top. The photographs include a 5-mm grid, with grid lines of 0.3mm. All pieces of microplastics collected were less than 5mm except (c) which was slightly larger than 5mm.

Research paper has been published in the following.

"Microplastics in the Southern Ocean", Marine Pollution Bulletin

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