Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.scitotenv.2024.176210

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.scitotenv.2024.171871

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.scitotenv.2024.172837

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Language：English   Publisher：The Japanese-French Oceanographic Society  

Publications describing the concentration and distribution of plastic litter, microplastics（>
350 μm and < 5mm）, and small microplastics（< 350 μm）in seawater, sediments, and
beaches around the coast of Japan are reviewed. Plastics from food packaging and polyethylene
plastic bags are widely distributed along the Japanese coast. The concentration of expanded
plastics and plastic bottles is high in the region of the East China Sea. Microplastics on the sea
surface are widely distributed along the coast of Japan, and the average concentration of microplastics
in seawater off the Japanese coast is very high compared with other regions of the
world. A two-ply, double neuston net, comprising an internal net with a 350-μm mesh and an
outer net with a 50-μm mesh, was used to quantify small microplastics（> 50 μm, < 350 μm）
and microplastics（> 350 μm, < 5 mm）in Tokyo Bay. The concentration of small microplastics
was about 10 times the concentration of microplastics. Conventional techniques used to quantify
microplastics may underestimate plastic concentrations.

DOI： 10.32211/lamer.61.3-4_165

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CiNii Research

Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.rsma.2023.103287

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Language：English   Publishing type：Research paper (scientific journal)  

Carbonyl index (CI) is a measure of the degradation status of microplastics. While many studies address environmental factors of microplastic degradation, intrinsic factors like physical properties, spectral properties, baseline correction, and CI calculation methods are less explored. This research focused on these aspects using surface seawater samples. We found that color and shape have limited dependence on particle size or signal-to-noise ratio (SNR). Baseline correction can significantly alter CI values, with the direction of the shift depending on the methods used. Additionally, most CI values before and after baseline correction and those calculated using different methods tend to be strongly correlated. Using the selected CI calculation methods, we found that CI values varied significantly by shape and color. CI's relation to the similarity between the sample and its pristine form suggests an alternative degradation measure. Our findings emphasize the need for standardized CI calculation methods.

DOI： 10.1016/j.marpolbul.2023.115700

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Language：English   Publishing type：Research paper (scientific journal)  

In recent years, significant efforts have been dedicated to measuring and comprehending the impact of microplastics (MPs) in the ocean. Despite harmonization guidelines for MPs research, discrepancies persist in the applied methodologies and future challenges, mostly for the smaller fractions (< 100 μm). Whether intentional or accidental, ingesting plastic particles by zooplankton can lead to incorporating this pollutant into aquatic food chains. Therefore, zooplankton can serve as a suitable proxy tool for assessing the presence of plastic particles in ocean waters. However, reliable information is essential for conducting experimental laboratory studies on the impact of MPs ingestion by zooplankton organisms. Using zooplankton as a research tool for MPs offers numerous advantages, including similar sampling methodologies and study techniques as MPs and particle data integration over space and time. The scientific community can gain novel perspectives by merging zooplankton studies with MPs research. This review explores key aspects of using zooplankton as a tool for MPs research in water samples, encompassing various views such as particles ingestion in natural environments, particle quantification in zooplankton samples (past and future), ecotoxicological and toxicology model studies. By leveraging the potential of zooplankton research, advancements can be made in developing innovative techniques for MPs analysis.

DOI： 10.1016/j.scitotenv.2023.167329

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

For the detection of microplastics (MPs) in aquatic biota using Fourier transform infrared spectroscopy (FTIR), the ability to remove organic matter (OM) in pretreatment steps is essential to increase the time efficiency of MPs measurement and method uniformity. In principle, decreasing OM can be achieved by increasing the number of pretreatment steps. However, MPs are lost in proportion to the number of transfers between each step. Therefore, we have created a "Cylindrical MPs Fractionator" composed of commercially available materials. This container allows for a six-step pretreatment process that is designed to increase the removal capacity of OM with only one transfer to prevent the loss of MPs.•Biological or sediment samples are placed in the extractor and subjected to chemical treatment and density separation.•Residues containing MPs are obtained on filters by vacuum filtration.•After additional chemical treatment of the obtained residue, the components of the residue are identified by microscopic FTIR.This method removed 99.3% of OM and recovered 88.5% of MPs. The presenting method confirmed that this can be used with the same process for 11 organisms and sediments from estuarine ecosystem in Japan as models.

DOI： 10.1016/j.mex.2023.102396

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Language：English   Publishing type：Research paper (scientific journal)  

Freshwater rivers are considered the major route for microplastics (MPs), yet limited studies have been reported on MPs in freshwater river fish, especially in Bangladesh. This research reveals the intake of MPs by the giant river catfish Sperata seenghala, collected from the Meghna River, which is the only outlet of the Ganges-Brahmaputra River. Three locations, namely, Chandpur Sadar, Bhola Sadar, and Char Fasson, along the Meghna River, were selected in order to investigate the gastrointestinal tracts (GIT) of the fish. Ninety percent (n=27) of fish (n=30) were contaminated, with fragment-shaped MPs (65%) as the most abundant among the four types. A total of 179 MP particles were detected using micro-Fourier transformed infrared spectroscopy (μ-FTIR), with an average of 5.96 ± 1.32 MP particles per fish. Among the four size groups, the highest proportion of MPs (54%) occurred in the 45-100 μm group; the dominant color among the seven color groups was white (30%). The highest quantity of MPs was found in the relatively densely populated Chandpur Sadar region. Polypropylene-polyethylene copolymer (PP-PE, 23%) was proportionally dominant among the 15 types. No significant relationship was found between the total number of observed MPs and the GIT weight. This study will help us to understand MP pollution in S. seenghala that may transmit to the human body through the food chain.

DOI： 10.1007/s11356-023-28750-z

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Language：English   Publishing type：Research paper (scientific journal)  

Microplastics have contaminated the ocean in large quantities and are widely distributed throughout the world. Thus, our understanding of the concentration of microplastics in various environments should be increased. However, current methods to detect microplastics require considerable effort and expensive equipment. In this study, we developed a fluorescence staining technique using coumarin 6 and examined its effectiveness. A mixture of acetone and ethanol was used as the solvent, and 10 different types of plastics were able to be stained with coumarin 6. The fluorescence peak for coumarin 6 staining was approximately 500 nm for each plastic type. The optimal immersion time and coumarin 6 concentration for staining were determined to be 60 min and 1 mg L-1, respectively. Using this technique, we were able to stain all of the microplastics obtained from samples collected in Tokyo Bay seawater.

DOI： 10.1016/j.marpolbul.2023.115167

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DOI： 10.1016/j.marpolbul.2023.114818

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Language：English   Publishing type：Research paper (scientific journal)  

A nested double neuston net was prepared and used to collect samples from the surface of coastal waters around Japan to obtain information about the properties of both small microplastics (SMPs; <350 μm) and large microplastics (LMPs; >350 μm). The SMP concentrations ranged from 1000 to 5900 pieces m-3 in the open ocean and averaged approximately 3000 pieces m-3 in the inner part of Tokyo Bay. The SMP concentrations were around 20-60 times greater than the LMP concentrations. By analyzing the seawater, we obtained a microplastic size distribution that spanned 50-5000 μm. The LMPs mainly comprised packaging-related plastics, such as polyethylene (PE) and polypropylene, while the SMPs were dominated by paint-related plastics. SMPs derived from packaging materials (e.g., PE) may have gradually sank down from the sea surface when they were smaller than 600 μm.

DOI： 10.1016/j.marpolbul.2022.114245

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.rsma.2022.102201

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Language：Others  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ecss.2021.107552

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.marpolbul.2021.112799

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.marpolbul.2021.112749

Language：Others  

Statistical Analysis of Surface Circulation in Sagami Bay Using High-Frequency (HF) Radar

DOI： 10.1007/978-3-030-43484-7_4

Language：English  

DOI： 10.1007/s10872-019-00514-9

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Language：Japanese  

本論文182 ページの式 (2)，(3)，183 ページの式 (4) 中の指数符号，並びに係数に著者校正中の不注意によるミスプリントがありましたので，以下のように訂正いたします。なお，式 (4) を図示したFig. 12, 13 の実線は訂正した式で図示されているので，変更はありません。また，この訂正による論文内容の変更はありません。私どもの不注意でご迷惑をおかけしたことをお詫び申し上げます。

DOI： 10.5928/kaiyou.24.2_77

Language：Others  

Event date： 2018

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