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To understand the relationship between the radioactive cesium (Cs) concentration in muscle of Japanese flounder Paralichthys olivaceus and the species' biological characteristics (size, sex, and age) under conditions of ecological equilibrium (i.e., distributed among ecosystem components over sufficient time, and with nearly constant ratios of Cs concentration in organisms to the concentration in water) as existed before the accident at the Fukushima Dai‐ichi Nuclear Power Station (FDNPS), Japan, in 2011, we examined stable Cs, as it is thought to exist in equilibrium in the environment and behave similarly to radioactive Cs in aquatic animals. The concentration of stable Cs in 241 P. olivaceus (range 216–782 mm total length [TL]) collected in Sendai Bay, approximately 90 km north of the FDNPS, in June–July 2015 was expressed as an exponential function with size as an independent variable; the results show the concentration of stable Cs doubled with an increase in TL of 442 mm. Next, to evaluate the cause of the size‐dependent change in stable Cs concentration, we examined 909 individuals (200–770 mm TL) collected in September 2013–July 2015 to determine their feeding habit based on size. Analysis of the frequency of occurrence of prey organisms in stomach contents showed that sand lance Ammodytes japonicus (55–180 mm standard length [SL]) was the most consistently consumed across size classes. Analysis on a wet‐mass basis showed that A. japonicus and anchovy Engraulis japonicus (65–130 mm SL) were the main food of P. olivaceus sized 200–599 mm TL, whereas chub mackerel Scomber japonicus (120–230 mm SL) and two species of flatfishes (180–205 mm SL) were abundant in the diet of P. olivaceus sized ≥600 mm TL. All these prey items were presumed to have similar concentrations of stable Cs. Based on the above, the effect of diet on the relationship between stable Cs in muscle and fish size was considered negligible. That the diet of P. olivaceus largely did not change with size was also confirmed by C and N stable isotope ratios in P. olivaceus and their prey species. Therefore, the Cs–size relationship is probably determined by changes in the balance between the rate of Cs intake from food and seawater and the excretion rate during growth, both of which change as functions of body mass. Values of stable Cs concentrations among environmental components and animals appear to be a valid indicator for understanding the radioactive Cs distribution in the marine environment and aquatic animals under the equilibrium state, as existed before the 2011 nuclear accident. [ABSTRACT FROM AUTHOR]

On 21 November 2016, a Mw 6.9 intraplate earthquake occurred off the Fukushima coast in Japan, triggering a moderate-size tsunami with amplifications and long oscillations along the Sendai Bay coast. Here, we apply a hybrid approach to hindcast the wave characteristics in the Sendai Bay during the 2016 tsunami event, by analyzing coastal tide records, spectral analyses, and tsunami simulations. Our analysis shows that tsunami wave on tide stations mainly carried wave periods of 3.8–22.5 min, triggered by source periods of 18.5–22.5 min. The long oscillation in Sendai Bay was due to longer period of >28.8 min, affected by the presence of edge waves and oscillation of Sendai Bay. High-energy wave was found to be significant in most oscillation periods inside the Sendai Bay and around the Oshika Peninsula. The spatial distribution of maximum spectral and simulated tsunami amplitudes also reveal that the radiated tsunami energy was entrapped in the nearshore areas, resulting in resonance amplifications in the Sendai Bay. • Hindcast of the November 2016 Fukushima earthquake tsunami. • Local amplifications and long tsunami oscillations in the Sendai Bay. • Tsunami wave on tide stations mainly carried wave periods of 3.8–22.5 min, triggered by source periods of 18.5–22.5 min. • Long oscillations of tsunami in Sendai Bay were due to longer wave periods of >28.8 min, affected by edge waves and oscillation of Sendai Bay. [ABSTRACT FROM AUTHOR]

A catastrophic undersea megathrust earthquake of magnitude 9.0 off the coast of Japan occurred at 14:46 JST on Friday, 11 March 2011. The earthquake triggered powerful tsunami waves, and the tsunami precipitated Fukushima nuclear accidents. After the terrible earthquake, many people fled from the nuclear accident and arrived at places far from the nuclear power plant. In this article, I present a story of one measure devised to deal with the problem of the Fukushima nuclear accident at a regional hospital of Fukushima prefecture, Aizu General Hospital, which is located far from the Fukushima nuclear plant. In addition, I briefly report the current situation of Fukushima prefecture after the 2011 Great East Japan earthquake. In our hospital, the countermeasure headquarters was established to supply medical care for those who had been injured by tsunami waves and the Fukushima nuclear accident. Especially, the screening for radioactive exposure using a dosimeter to take decontamination measures for cases of external exposure was extremely important task. Nevertheless, because the accurate knowledge related to radioactive contamination didn't provide, most medical staff fell into confusion. Fukushima prefecture has been 'shrinking' since the nuclear accident. However, today, although some hot spots remain in residential areas, the radioactive contamination is decreasing little by little. Many people in Fukushima Prefecture advance as one, facing forward. Recently, decontamination projects started. Efforts must be continued over a long period. [ABSTRACT FROM AUTHOR]