Rei Yamashita

• The University of Tokyo

Understanding the spatiotemporal dynamics of microplastics on the ocean surface is crucial for assessing their impact on marine ecosystems and human health; however, long-term fluctuations have not been extensively studied. We present a long-term empirical data set on floating marine plastic debris collected from 1949 to 2020 around Japan in the we...

The distribution of floating plastic debris around the Kuroshio Current which transports plastics from the coastal waters of Asian countries to North Pacific subtropical gyre, was investigated in 2014. The mean abundance and weight of plastic debris on the sea surface were 100,376 counts/km2 and 446.16 g/km2, respectively. Intensive plastic accumul...

Marine debris is present between the sea surface and the sea floor, but few studies have investigated plastic in water column. Therefore, we chose longnose lancetfish (Alepisaurus ferox) as a sample, this study samples mesopelagic species that ingest marine debris in the water column. We conducted a survey of the stomach contents of longnose lancet...

Plastic pollution, and its associated impacts on marine fauna due to chemical contamination, is an area of growing global concern. We analyzed 145 preen gland oil samples from 32 seabird species belonging to 8 families with different foraging habits and life history strategies from around the world for plastic additives and legacy persistent organi...

Polybrominated diphenyl ethers (PBDEs) were measured in plastic resin pellets collected from 65 beaches across 27 countries worldwide. They were detected at 49 locations at concentrations of the sum of 49 congeners of up to 46 ng/g-pellet and a median of 2 ng/g-pellet. These values are one to two orders of magnitude lower than those of polychlorina...

Floating plastic debris was investigated in the transition region in the North Pacific between 141°E and 165°W to understand its transportation process from Asian coast to central subtropical Pacific. Distribution was influenced primarily by the current system and the generation process of the high concentration area differed between the western an...

Anthropogenic marine debris is a threat to marine organisms. Understanding how this debris spatially distributes at sea and may become associated with marine wildlife are key steps to tackle this current issue. Using bird-borne GPS- and video-loggers on 13 black-footed albatrosses Phoebastria nigripes breeding in Torishima, Japan, we examined the d...

Sonic boom prediction around buildings has previously been conducted under the assumption of linear wave propagation. In this work, a more detailed analysis considering the nonlinear effect is achieved by means of computational fluid dynamics (CFD). The two-dimensional Euler equations are solved by employing a level set method for tracking a moving...

Microplastic pollution in marine environments is an emerging global issue revealing the importance of microplastic monitoring. Although numerous papers have been published in recent years in relation to microplastics, the methods and techniques for identifying and quantifying them remain underdeveloped, and many researchers are working to develop o...

Plastic pollution in the oceans is a priority environmental issue. The recent increase in research on the topic, coupled with growing public awareness, has catalyzed policymakers around the world to identify and implement solutions that minimize the harm caused by plastic pollution. To aid and coordinate these efforts, we surveyed experts with scie...

This paper develops a full-field direct numerical simulation methodology of sonic boom in a stratified atmosphere. The entire flow field, ranging from the near field around a supersonic body to the far field extending to the ground, is modeled by the three-dimensional Euler equations with a gravitational source term. Thus far, it has been solved us...

Plastic debris is ubiquitous and increasing in the marine environment [1]. A wide range of marine organisms ingest plastic, and its impacts are of growing concern [2]. Seabirds are particularly susceptible to plastic pollution because of high rates of ingestion [3]. Because marine plastics contain an array of hazardous compounds, the chemical impac...

PCBs and PBDEs in microplastics and zooplankton collected in surface water at 27 locations in the Pacific Ocean and around the coast of Japan were investigated. Both PCBs and PBDEs were observed in buoyant microplastics, even in smaller particles of 0.315-1 mm. Concentrations of Σ13 PCBs were 0.04-124 ng/g, and were higher in urban bay areas such a...

Longnose lancetfish (Alepisaurus ferox) may has been studied as an indicator of marine pollution caused by marine litter. The objectives of this study were to determine the difference in frequency of occurrence of plastics ingested by longnose lancetfish in different ocean area. In this study, we compared the incidence and characteristics of anthro...

Situated at high positions on marine food webs, seabirds accumulate high concentrations of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), and hexachlorocyclohexanes (HCHs). Our previous studies proposed the usefulness of seabirds preen gland oil as a nondes...

Marine plastic debris, including microplastics <5 mm, contain additives as well as hydrophobic chemicals sorbed from surrounding seawater. A volunteer-based global monitoring programme entitled International Pellet Watch (IPW) is utilizing the sorptive nature of plastics, more specifically of beached polyethylene (PE) pellets, in order to measure p...

Field observations of seabirds and whales indicate transfer of chemicals from ingested plastics to the tissue of organisms which have ingested the plastics. To determine the significance of plastic-mediated exposure of chemicals, it should be compared with natural prey-mediated exposure. In case where background pollution is high, plastic-mediated...

Following the Fukushima Dai-ichi Nuclear Power Station accident, regional road dust, heavily contaminated with radiocesium, now represents a potential source of radiocesium pollution in river water. To promote effective countermeasures for reducing the risk from radiocesium pollution, it is important to understand its sources. This study evaluated...

Oil pollution in the marine environment is an unavoidable problem due to chronic input from local sources, particularly in urban areas and oil spills. Oil pollution not only causes immediate physical damages to surrounding wildlife but also some components, including higher molecular weight PAHs, can persist in the environment for many years and po...

Plastic resin pellets collected at Minh Chau island and Ba Lat estuary between 2007 and 2014 in Vietnam were analyzed for dichloro-diphenyl-trichloroethanes (DDTs), polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs). The study was carried out as part of the International Pellet Watch program for monitoring the global distribution of...

The assimilation efficiency and growth of Rhinoceros Auklet Cerorhinca monocerata chicks (30-35 age of days) fed with Japanese Sand Lance Ammodytes personatus and Antarctic Krill Euphausia superba were investigated. Chicks were fed 79.4 ± 3.1 gwet /d (mean ± SD) of sand lance, which included 497.2 ± 14.9 kJ energy, 4.3 ± 0.2 g lipid, and 12.3 ± 0.5...

Our previous study suggested the transfer of polybrominated diphenyl ether (PBDE) flame-retardants from ingested plastics to seabirds' tissues. To understand how the PBDEs are transferred, we studied leaching from plastics into digestive fluids. We hypothesized that stomach oil, which is present in the digestive tract of birds in the order Procella...

The release of radiocesium from the Fukushima Dai-ichi Nuclear Power Plant caused environmental contamination. We analyzed sources, behavior, and temporal trends of radiocesium by 1-year monitoring in an urban river, the Ohori River. The concentrations of 137 Cs in both particulate and dissolved phases decreased to ~ 16% within 1 year. The partitio...

Plastic resin pellets collected at 11 beaches covering the whole Ghanaian coastline were analyzed for polychlorinated biphenyls (PCBs). PCB concentrations (∑13 congeners) were higher in Accra, capital city, and Tema (39-69ng/g-pellets) than those in rural coastal towns (1-15ng/g-pellets) which are close to global background, indicating local inputs...

This paper describes the effectiveness of the direct simulation for the sonic boom prediction over the whole computational domain from the body to the ground and the nature of the sonic boom propagation for the hypersonic vehicle. Both the near and far fields around an axi-symmetric paraboloid are numerically obtained by the axi-symmetric Euler ana...

Ocean-scale monitoring of pollution is challenging. Seabirds are useful indicators because they travel over a broad foraging range. Nevertheless, this coarse spatial resolution is not fine enough to discriminate pollution in a finer scale. Previous studies have demonstrated that pollution levels are higher in the Sea of Japan and South and East Chi...

We analyzed polybrominated diphenyl ethers (PBDEs) in abdominal adipose of oceanic seabirds (short-tailed shearwaters, Puffinus tenuirostris) collected in northern North Pacific Ocean. In 3 of 12 birds, we detected higher-brominated congeners (viz., BDE209 and BDE183), which are not present in the natural prey (pelagic fish) of the birds. The same...

Polybrominated diphenyl ethers (PBDEs) are extensively used as flame retardants in many consumer products, and leachates from landfills have been identified as one of the possible sources of PBDEs in the environment. Meanwhile, the unprecedented economic and population growths of some Asian countries over the last decade have led to significant inc...

Plastic resin pellets collected from remote islands in the Pacific, Atlantic, and Indian Oceans and the Caribbean Sea were analyzed for polychlorinated biphenyls (PCBs), dichloro-diphenyltrichloroethane and its degradation products (DDTs), and hexachlorocyclohexanes (HCHs). Concentrations of PCBs (sum of 13 congeners) in the pellets were 0.1-9.9 ng...

Plastic resin pellets collected from remote islands in open oceans (Canary, St. Helena, Cocos, Hawaii, Maui Islands and Barbados) were sorted and yellowing polyethylene (PE) pellets were measured for polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and the degradation products (DDTs), and hexachlorocyclohexanes (HCHs) by gas chroma...

We investigated the plastics ingested by short-tailed shearwaters, Puffinus tenuirostris, that were accidentally caught during experimental fishing in the North Pacific Ocean in 2003 and 2005. The mean mass of plastics found in the stomach was 0.23 g per bird (n=99). Plastic mass did not correlate with body weight. Total PCB (sum of 24 congeners) c...

To understand the spatial variation in concentrations and compositions of organic micropollutants in marine plastic debris and their sources, we analyzed plastic fragments (∼10 mm) from the open ocean and from remote and urban beaches. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), dichloro-diphenyl-trichloroethane and i...

Seabirds and large fishes are important top predators in marine ecosystems, but few studies have explored the potential for competition between these groups. This study investigates the relationship between an observed biennial change of pink salmon (Oncorhynchus gorbuscha) biomass in the central Bering Sea (23 times greater in odd-numbered than in...

Plastics debris in the marine environment, including resin pellets, fragments and microscopic plastic fragments, contain organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons, petroleum hydrocarbons, organochlorine pesticides (2,2'-bis(p-chlorophenyl)-1,1,1-trichloroethane, hexachlorinated hexanes), poly...

Oil secreted from the preen gland (located at the base of the tail feathers) of seabirds can be collected from live birds. We determined PCB concentrations and profiles in the preen gland oil and corresponding abdominal adipose tissue collected from 30 seabirds (2 orders, 3 families, 10 genera, 13 species) to examine the utility of the oil as a mon...

Concentrations of polychlorinated biphenyls (PCBs) in beached resin pellets were examined to reveal variability between individual particles and differences among beaches. Fifty-five resin pellets from a beach in Tokyo were individually analyzed for PCBs, and showed concentrations ranging from <28 to 2,300 ng/g. This indicates that concentrations a...

NOT THE ABSTRACT; there is no one, but this in the Introduction. Marine plastics including plastic fragments and plastic resin pellets are distributed widely in the ocean. Because the marine plastics contain organic pollutants [1], their adverse effects have been of great concern. To assess the risks of plastic-associated chemicals, understanding...