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The tire industry has employed effective CO2 reduction measures in the form of retread tires, which replace only those components that are exposed to the road's surface. Due to safety concerns, lack of manufacturing technology, high cost, and other issues, retread tires in passenger cars are currently unavailable in Japan. This study aims to analyze the production cost and environmental impacts of retread tires in passenger cars in Japan. This study considered investments in and economies of scale of retread tires, which have lower profit margins than new tires after safety and manufacturing technology issues have been resolved; this is done when the carbon tax is equal to that in the EU. This reserach further examined the proportion of retread tires and new tires that are produced. The primary goal of this study is to determine which ratio of retread vs. new tire production is feasible for an optimal business portfolio. If a carbon tax equivalent to that in the EU was introduced in Japan and each company offered retread tires for passenger cars, this setup would not be profitable and overall costs would need to be lowered. To achieve this cost-effectiveness, it is necessary to extend the life of the equipment and to lower the initial investment. Furthermore, by calculating the costs involved using realistic production expenses, a more realistic cost for the introduction of retread tires for passenger cars can be achieved. [ABSTRACT FROM AUTHOR]

We present petrological evidence of the shallow magmatic processes that may have supplied heat and gas to the eruption of Mount Ontake, Japan, on 27 September 2014, which resulted in 63 fatalities. Ash from the eruption comprises primarily hydrothermally altered, white-toned rock fragments. However, the ash contains trace amounts (< 0.7 wt%) of vitreous less-altered particles (LAPs), which are only altered on their surfaces, suggesting rapid ascent through the hydrothermal system. The LAPs are classified into two categories: "glassy" and "crystalline." Glassy LAPs comprise high-silica rhyolitic glass (74–83 wt% SiO2) with rounded quartz, chalcedony-free vesicles, and reversely zoned plagioclase (cores = 47 mol% An; rims = 70 mol% An), indicating magma re-heating. Crystalline LAPs have a groundmass-like texture that suggests eutectic crystallization at shallow depths. Thermodynamic calculations indicate that the pre-eruptive temperatures of the glassy and crystalline LAPs were 700–1300 °C and ~ 700 °C, respectively, and that the storage depth was < 4 km (pressure < 100 MPa). The observed petrological features suggest that the LAPs were sourced from a magma recently intruded at shallow depths. Although crustal deformation (i.e., the volume change associated with magmatic intrusion) was insignificant prior to the 2014 eruption, a clear signature of crustal deformation was observed in 2007, the source of which was located 3 km below the summit. We suggest that the magma that was intruded 3 km below the summit in 2007 supplied the heat and gas for the 2014 phreatic eruption. [ABSTRACT FROM AUTHOR]

Aim: A nationwide survey of acute liver failure (ALF) and late‐onset hepatic failure (LOHF) has revealed that the outcomes of recent patients whose diseases were caused by infection with hepatitis A virus (HAV) have worsened, compared with those of previously reported patients. The factors associated with this deterioration were evaluated. Methods: A total of 83 patients with HAV infection seen between 1998 and 2015 were enrolled. All the patients had a prothrombin time–international normalized ratio of 1.5 or more and hepatic encephalopathy of grade 2 or more severe. The demographic and clinical features of 45 patients seen prior to 2003 (cohort 1) and 38 patients seen during 2004 and thereafter (cohort 2) were compared. Results: Three and four patients in cohort 1 and cohort 2, respectively, received liver transplantations; the survival rates among the remaining patients were 56% for cohort 2 and 79% for cohort 1 (P < 0.05). The mean age (±standard deviation) of the patients was higher in cohort 2 than in cohort 1 (58 ± 11 vs. 48 ± 13 years; P < 0.01). The percentages of patients with underlying metabolic diseases were 22% in cohort 1 and 61% in cohort 2 (P < 0.01). Diabetic mellitus was more common among deceased patients than among rescued patients (29% vs. 8%; P < 0.05) among patients who did not receive liver transplantations, and a multivariate analysis revealed that patient age and disease type were significantly and independently associated with the outcome. Conclusion: The outcomes of recent patients with ALF or LOHF caused by HAV infection have recently worsened mainly because of an increase in underlying metabolic diseases as a consequence of aging. [ABSTRACT FROM AUTHOR]

Background: A nationwide survey was performed to clarify the recent status of acute liver failure (ALF) and late-onset hepatic failure (LOHF) in Japan.Methods: Two-step surveys for patients with ALF and LOHF meeting the Japanese diagnostic criteria were performed annually in 782 hospitals. The clinical features of the patients were then compared to those reported in previous surveys.Results: In total, 1554 and 49 patients with ALF and LOHF, respectively, who were seen between 2010 and 2015 were enrolled. The subjects were classified into 1280 patients with hepatitis (642 non-comatose and 638 comatose) and 323 patients without hepatitis (190 non-comatose and 133 comatose). Compared with patients seen between 1998 and 2009, an older patient age and a higher percentage of underlying extrahepatic disease were observed. Although hepatitis virus infection was the most frequent etiology, the percentage of patients with this etiology had decreased, compared with previous cohorts, while the percentages of patients with drug-induced liver injuries, autoimmune hepatitis, and an indeterminate etiology had increased. Liver transplantation was performed in 170 patients (10.6%), whereas artificial liver support with plasmapheresis and/or hemodiafiltration were performed for most of the comatose patients. The outcomes of comatose patients were unfavorable, similar to previous surveys, especially the outcomes of hepatitis B virus carriers, including those with de novo hepatitis B (survival rate of 5.4% without liver transplantation).Conclusion: Although the clinical features, including the etiologies, of patients with ALF and LOHF have changed, the outcomes of patients have not improved in recent years. [ABSTRACT FROM AUTHOR]

Aim: To establish diagnostic criteria for acute‐on‐chronic liver failure (ACLF) in Japan, a multicenter pilot survey was carried out to examine the usefulness of overseas criteria in patients with chronic liver diseases manifesting acute decompensation. Methods: Patients fulfilling the Asian‐Pacific Association for the Study of the Liver (APASL), European Association for the Study of the Liver (EASL), or Chinese Medical Association (CMA) criteria for decompensation were enrolled from eight institutions in Japan, and the clinical features were evaluated. Results: Among 112 patients, 109 patients (97.3%) fulfilled the APASL criteria for decompensation; 7 patients were excluded because the decompensation had been provoked by gastrointestinal bleeding. Consequently, 102 patients (91.1%) were diagnosed as having ACLF according to the APASL definition. Among the patients who fulfilled the APASL criteria for decompensation, the etiologies of the underlying liver diseases were alcohol abuse in 59 cases (54.1%) and hepatitis B or hepatitis C virus infection in 24 (22.0%). The acute insults were alcohol abuse in 50 (45.9%), bacterial infection in 26 (23.9%), and exacerbation of underlying liver disease in 14 (12.8%). Fifty‐four patients (49.5%) satisfied the CMA criteria, but the survival rates were similar between patients who did and those who did not meet the criteria. When 84 patients with underlying cirrhosis were classified according to the EASL–Chronic Liver Failure (Clif) Consortium criteria, the survival rates differed according to grade: 67.6% (23/34) for patients without ACLF, and 41.2% (14/34) and 18.8% (3/16) for those with grade 1/2 and grade 3 ACLF, respectively. Conclusion: The APASL definition was suitable for screening Japanese patients with ACLF, including those whose conditions were triggered by gastrointestinal bleeding, and the EASL‐Clif Consortium criteria were useful for predicting outcome. [ABSTRACT FROM AUTHOR]

We estimated time scales of magma-mixing processes just prior to the 2011 sub-Plinian eruptions of Shinmoedake volcano to investigate the mechanisms of the triggering processes of these eruptions. The sequence of these eruptions serves as an ideal example to investigate eruption mechanisms because the available geophysical and petrological observations can be combined for interpretation of magmatic processes. The eruptive products were mainly phenocryst-rich (28 vol%) andesitic pumice (SiO 57 wt%) with a small amount of more silicic pumice (SiO 62-63 wt%) and banded pumice. These pumices were formed by mixing of low-temperature mushy silicic magma (dacite) and high-temperature mafic magma (basalt or basaltic andesite). We calculated the time scales on the basis of zoning analysis of magnetite phenocrysts and diffusion calculations, and we compared the derived time scales with those of volcanic inflation/deflation observations. The magnetite data revealed that a significant mixing process (mixing I) occurred 0.4 to 3 days before the eruptions (pre-eruptive mixing) and likely triggered the eruptions. This mixing process was not accompanied by significant crustal deformation, indicating that the process was not accompanied by a significant change in volume of the magma chamber. We propose magmatic overturn or melt accumulation within the magma chamber as a possible process. A subordinate mixing process (mixing II) also occurred only several hours before the eruptions, likely during magma ascent (syn-eruptive mixing). However, we interpret mafic injection to have begun more than several tens of days prior to mixing I, likely occurring with the beginning of the inflation (December 2009). The injection did not instantaneously cause an eruption but could have resulted in stable stratified magma layers to form a hybrid andesitic magma (mobile layer). This hybrid andesite then formed the main eruptive component of the 2011 eruptions of Shinmoedake. [ABSTRACT FROM AUTHOR]

We present precise geodetic and satellite observation-based estimations of the erupted volume and discharge rate of magma during the 2011 eruptions of Kirishima-Shinmoe-dake volcano, Japan. During these events, the type and intensity of eruption drastically changed within a week, with three major sub-Plinian eruptions on January 26 and 27, and a continuous lava extrusion from January 29 to 31. In response to each eruptive event, borehole-type tiltmeters detected deflation of a magma chamber caused by migration of magma to the surface. These measurements enabled us to estimate the geodetic volume change in the magma chamber caused by each eruptive event. Erupted volumes and discharge rates were constrained during lava extrusion using synthetic aperture radar satellite imaging of lava accumulation inside the summit crater. Combining the geodetic volume change and the volume of lava extrusion enabled the determination of the erupted volume and discharge rate during each sub-Plinian event. These precise estimates provide important information about magma storage conditions in magma chambers and eruption column dynamics, and indicate that the Shinmoe-dake eruptions occurred in a critical state between explosive and effusive eruption. [ABSTRACT FROM AUTHOR]

We estimated the depth of the magma chamber system beneath Usu volcano, one of the most active volcanoes in Japan, by melting experiments on the eruptive product of the ad 1663 plinian eruption (Us-b pumice). This pumice is a low-K rhyolite with a K2O content of only 1 wt %. The experiments were conducted using internally heated pressure vessels at 98–392 MPa and 700–900°C under nickel–nickel oxide (NNO)-buffered and water-saturated conditions. The pre-eruptive conditions of the 1663 eruption were estimated to be 780 ± 20°C and around 200–250 MPa. The phase equilibria, mineral compositions (plagioclase, orthopyroxene, and Fe–Ti oxides), melt composition, and melt fraction are all in agreement with this conclusion. This pressure corresponds to a depth of 8–10 km, assuming a lithostatic condition with an appropriate crustal density structure. The magma was at near water-saturated conditions. Deviation between the estimated pressure and the true total pressure was estimated to be less than 50 MPa. The Us-b magma was under very uniform conditions with a temperature variation of less than c. 20°C, deduced from the narrow range of the phase equilibrium conditions (crystallizing orthopyroxene without quartz) and the homogeneous composition of plagioclase (c. An 41–45). We also estimated the pre-eruptive conditions of post-1663 eruptions, where it has been proposed that two magmas (high-P and low-P members) mixed prior to each eruption. The pressure of the deep magma was also around 200–250 MPa, whereas that of the shallow magma was estimated to be 100–150 MPa (4–6 km depth), according to the pressure dependence of the plagioclase composition obtained in our experiments. Thus, there appear to be two magma chambers beneath Usu volcano. Our estimate is consistent with geophysical observations made during the 2000 eruption, including identification of an inflation and deflation source at a depth of 10 km, a low-frequency (12 s) tremor source at a depth of 5–6 km, and an earthquake swarm at a depth of less than 4 km. The depth of the rhyolitic magma chamber (8–10 km) is deeper than the level of neutral buoyancy for the magma, and is comparable with that of mafic magma that existed beneath the rhyolitic magma. This suggests that the depth of the 8–10 km deep magma chamber was controlled by the emplacement of the mafic magma and that the rhyolitic magma was produced at that depth. When compared with other silicic magma systems, the Usu magma system has similar characteristics, including a similar pre-eruptive pressure of around 200 MPa and a pressure decrease with time, suggesting upward magma movement towards a neutral buoyancy level. The low potassium content of the Usu magma prohibited crystallization of biotite, K-feldspar or hornblende, which are common phases in magmas with intermediate to high potassium contents. The absence of hydrous minerals at near-liquidus conditions may cause a rapid increase in water content during crystallization of the magma, resulting in a rapid increase of the gas phase and frequent plinian or sub-plinian eruptions (six times since ad 1663) of the volcano. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to investigate the minimum effective dose of recombinant canine interferon-γ (rCaIFN-γ) for the treatment of dogs with atopic dermatitis (AD). Thirty-four dogs with AD from 17 animal hospitals in Japan were administered half or one-fifth of the approved rCaIFN-γ dose of 10 000 units/kg, three times a week for 4 weeks, followed by once weekly for an additional 4 weeks. Pruritus, excoriation, erythema and alopecia were evaluated and scored by the investigators on weeks 2, 4, 6, 8 and 12. The efficacy rate (number of excellent cases + number of good cases/total number of cases) at week 8 in the 2000 units/kg group was 36.4% for pruritus, 36.4% for excoriation, 45.5% for erythema and 36.4% for alopecia. In contrast, in the 5000 units/kg group, the efficacy rate was 64.3% for pruritus, 57.1% for excoriation, 78.6% for erythema and 78.6% for alopecia. The efficacy rate of the 5000 units/kg group was high for all signs evaluated and comparable to that of the 10 000 units/kg group reported in a previous study. The results of this study showed that 2000 units/kg of rCaIFN-γ is less effective than 5000 units/kg to treat dogs with AD, and the efficacy of the 5000 units/kg dose is comparable to that of 10 000 units/kg at week 8. [ABSTRACT FROM AUTHOR]

Renal biopsy is essential for the diagnosis of kidney diseases, but complications, particularly bleeding incidents, remain problematic. To evaluate the frequency of renal biopsy complications, and to reveal clinical and laboratory factors associated with overt bleeding complications, focusing on those available at hospital ward, we conducted a retrospective observational study for the period between 2001 and 2005 at Mie University Hospital in patients who underwent percutaneous renal biopsy of a native kidney. Of a total of 323 patients, 317 met the inclusion criteria. Only one patient (0.3%) required blood transfusion or intervention to stop bleeding. The mean decrease in hemoglobin (Hb) after biopsy was 0.43 ± 0.7 g/dL. Hb decreased ≥1.0 g/dL in 66 patients (20.8%) and ≥10% in 32 patients (10.1%). On ultrasonography, perirenal hematoma was detected immediately after biopsy in 273 patients (86.1%), and 41 patients (12.9%) showed hematoma ≥2 cm in width. Analgesics were required for back pain in 67 patients (21.1%). Vasovagal response developed in 31 patients (9.8%). Macrohematuria occurred in 12 patients (3.8%). Urinary catheter was used in 161 patients (50.8%). For Hb decrease ≥10% after biopsy, multivariate analysis revealed perirenal hematoma (≥2 cm) as a significant factor. Other significant factors were prolonged international normalized ratio of prothrombin time, elevated blood pressure on hospital admission, older age, increased serum creatinine level, and steroid use. Perirenal hematoma ≥2 cm on ultrasonography immediately after biopsy might well represent a predictive factor for bleeding complications. [ABSTRACT FROM AUTHOR]

Bortezomib is approved for the treatment of patients with relapsed or refractory multiple myeloma (MM), but only a few clinical studies for Japanese patients who were treated with bortezomib have been reported. We retrospectively analyzed 40 patients with relapsed or refractory MM who have received bortezomib at three collaborating centers in Miyagi prefecture in Japan. All the patients have been received bortezomib in combination with dexamethasone. Responses were determined using International Myeloma Working Group uniform response criteria. The overall response was observed in 30 patients (75%), including very good partial response in 8 patients (20%), and partial response in 22 patients (55%). The median time to disease progression was 8.7 months, and the median overall survival has not been reached. The factors affecting time to disease progression were International Staging System stage, serum beta2-microglobulin level, and number of treatment cycles. The most common grade 3 and 4 adverse events were thrombocytopenia (50%), peripheral neuropathy (25%), leukopenia (25%), and herpes zoster infection (25%). Thus, bortezomib is well tolerated and effective for Japanese patients with relapsed or refractory MM. Our results suggest that serum beta2-microglobulin level may be a marker of prognosis on bortezomib therapy for patients with relapsed or refractory MM although further studies are needed. [ABSTRACT FROM AUTHOR]

Background: Natural killer (NK) cells possess spontaneous cytotoxicity against tumors and virus-infected cells to play a major role in immunosurveillance and defense against the development of cancer, as well as bacterial and viral infections. The role of plasma lipoproteins in atherogenesis is well recognized, but the physiological relevance of their immunoregulatory properties is still questioned. In particular, it is unknown whether hypercholesterolemia should be considered a risk factor for diminished immunity in old age.Methods: To evaluate effects of plasma lipoprotein levels on immune function, we assessed the relation between plasma lipoprotein profiles and NK cell activity. NK cell activity was assayed by release of (51)Cr from K562 target cells, and concurrent plasma lipoprotein levels were measured in 47 samples of elderly males (mean age +/- SD, 66.6 +/- 1.7 years).Results: Univariate regression analyses revealed direct relations between NK cell activity and high-density lipoprotein cholesterol (r=.46, p<.001), apolipoprotein (Apo) A-1 (r=.48, p<.001), and Apo A-2 (r=.46, p<.005). In addition, multiple regression analyses showed a direct independent relation between NK cell activity and Apo A-1 (b=0.32+/-0.09 mg/dl, beta=0.48, and p <.001).Conclusion: NK cell activity is related directly to plasma Apo A-1 levels in elderly subjects. The mechanisms of this interaction are unknown, but Apo A-1 contributes to the composition of the antiatherogenic fraction of high-density lipoprotein and could also defend against infectious and malignant disease through a potential for NK cell activity. [ABSTRACT FROM AUTHOR]

Catastrophic sector collapse is a destructive volcanic process that occurs during the growth history of a volcano. Understanding the timing and causal mechanisms of sector collapse at individual volcanoes is essential for evaluating long-term volcano evolution and associated hazards. This paper describes the lithofacies, tephrostratigraphy, and radiocarbon dating of a debris avalanche deposit at Usu volcano, Japan, based on detailed field geological surveys, and proposes that uplift of soft substratum played an important role in destabilizing the young volcanic edifice. Usu is a Quaternary basaltic to andesitic stratovolcano that has an amphitheater at the summit. The basement of the volcano has been uplifted by 300–400 m relative to the surrounding area. The debris avalanche deposit is > 0.3 km3 in volume and displays well-preserved hummocky topography. The hummocks are composed of andesite blocks derived from the stratovolcano, and non-welded pyroclastic flow and fluvial deposits derived from the basement of the stratovolcano. Tephrostratigraphy and radiocarbon dating of charcoal samples from the debris avalanche deposit indicate that the sector collapse occurred at ~ 16 ka. The age of sector collapse, combined with previous geochronological data, enables reconstruction of the eruptive history of Usu as follows: (1) andesitic explosive eruption at 18–19 ka, (2) stratovolcano growth between 18 and 16 ka, (3) sector collapse at ~ 16 ka, (4) hiatus in volcanic activity for ~15,000 years, (5) rhyolitic Plinian eruption in AD 1663, and (6) dacitic dome-forming eruptions after AD 1663. This eruptive history indicates that the sector collapse occurred within ~3000 years of the onset of stratovolcano growth, much sooner than at other volcanoes where the timing of sector collapse is known. We infer that the sector collapse of such a young volcanic edifice was caused by a combination of dome-like uplifting/tilting (forced folding) of soft substratum, overloading of the volcanic edifice on the soft substratum, a NE–SW-trending fault system that deeply cuts the substratum, and possible magma intrusion within the edifice and associated earthquakes. Usu provides an excellent example of edifice instability that is characterized by uplift of soft substratum. Our new view of causal mechanisms of the sector collapse provides invaluable information for hazard assessment of Quaternary volcanoes. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: The purpose of this study was to investigate: (1) patient-based surgical outcomes of posterior lumbar interbody fusion (PLIF); (2) correlations between patient-based surgical outcomes and surgeon-based surgical outcomes; (3) factors associated with patient satisfaction.Summary Of Background Data: There have been no reports of patient-based surgical outcomes of PLIF for lumbar spondylolisthesis.Methods: Patients who underwent PLIF for L4 degenerative spondylolisthesis between 2006 and 2009 were reviewed (n = 121). Surgical outcomes were assessed 5 years after primary surgery using a questionnaire, a numerical rating scale (NRS) of pain, the 36-Item Short Form Health Survey (SF-36), the Japanese Orthopedic Association score (JOA score), and the recovery rate. The original questionnaire consisted of 5 categories, with scoring out of 100 points for surgery, satisfaction, improvement, recommendation to others, and willingness to undergo repeat surgery. Patient-based outcomes were divided into 3 groups according to the questionnaire responses as positive, intermediate, and negative and were compared with the JOA scores.Results: A total of 103 patients responded, for a response rate of 85%. The average patient-evaluated score for surgery was 82 points. The positive response rate in each category was 78% for satisfaction, 88% for improvement, 74% for recommendation, and 71% for repeat. The average pre- and postoperative JOA scores were 11.2 and 23.2, respectively. The average recovery rate was 68.5%. There were significant correlations between patient-based surgical outcomes and the JOA score. Furthermore, there were significant correlations between patient-based surgical outcomes and the NRS and physical component scores of the SF-36. Postoperative permanent motor loss was a major factor related to a negative response.Conclusion: The patient-evaluated score for surgery was 82 points. More than 70% of patients gave positive responses in all sections of the questionnaire. There were significant correlations between patient-based and surgeon-based surgical outcomes.Level Of Evidence: 2. [ABSTRACT FROM AUTHOR]

Background: In the Great East Japan Earthquake, the Japanese Red Cross Ishinomaki Hospital played an important role as a principal referral center within the Ishinomaki region, one of the most severely affected areas in eastern Japan. The present study describes the patient population, clinical characteristics, and time courses of the medical problems observed at this hospital.Methods: A retrospective survey of medical logs and records was conducted on the first 2 weeks after the earthquake to characterize orthopedic traumas and related disorders treated during this catastrophe. Patient number, severity of injuries, number of patients secondarily transported to the referral medical centers in the inland area, and the number of surgeries performed during the study period were investigated.Results: Totally, 7686 patients visited the hospital. Of which, 1807 patients suffered from exogenous diseases, such as trauma, burns, crush syndrome, deep venous thrombosis, and infectious diseases. Patients who suffered from hypothermia were the most frequently seen within the first 2 weeks after the earthquake. Interestingly, most patients' conditions were not severe and required only simple treatments. Four patients (0.2% of patients with exogenous diseases) were secondarily transported to the referral medical centers in the inland area and only four patients were surgically treated because of a lack of available implants, surgical devices, and electric power supply.Discussion and Conclusions: The Great East Japan Earthquake and subsequent tsunami, which occurred during an early spring afternoon, resulted in a unique orthopedic patient population, which included few severely injured patients compared with numerous deaths. We believe that each coastal region hospital should develop its own emergency medical care system to address future tsunami events while considering their surrounding environment. The information described in the present study should be important for preparation toward future events involving massive earthquakes followed by tsunami disasters. [ABSTRACT FROM AUTHOR]

Green stem disorder (GSD) is one of the most serious syndromes affecting soybean (Glycine max) cultivation in Japan. In GSD, stems remain green even when pods mature. When soybean plants develop GSD, seed surfaces are soiled by tissue fluid and seed quality is deteriorated during machine harvesting. We performed quantitative trait locus (QTL) analyses for GSD insensitivity using recombinant inbred lines (RILs; n = 154) derived from a cross between an insensitive line ('Touhoku 129') and a sensitive leading cultivar ('Tachinagaha') during a 6-year evaluation. Three effective QTLs were detected. The influences of these QTLs were in the following order: qGSD1 (LG_H) > qGSD2 (LG_F) > qGSD3 (LG_L). At these three QTLs, 'Touhoku 129' genotypes exhibited more GSD insensitivity than 'Tachinagaha' genotypes. The lower incidence of GSD for 'Touhoku129' was attributable primarily to these three QTLs because RILs harboring a 'Touhoku 129' genotype at the three QTLs exhibited a GSD incidence similar to that of 'Touhoku 129.' Although a limitation of this study is that only one mapping population was evaluated, this QTL information and the flanking markers of these QTLs would be effective tools for resolving GSD in soybean breeding programs. [ABSTRACT FROM AUTHOR]

Radionuclide ((131)I, (134)Cs, and (137)Cs) concentrations of monitored freshwater fish species collected from different habitats (rivers, lakes, and culture ponds) in Fukushima Prefecture during March 2011-December 2014 (total 16 species, n = 2692) were analyzed to present a detailed description of radionuclide contamination after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, and to elucidate species-specific spatiotemporal declining trends of (137)Cs concentration for their respective habitats. Low concentrations of (131)I (≤24 Bq kg(-1)-wet) were detected from only 11 samples collected during March-June 2011, demonstrating that (131)I transferred to freshwater fish were not intense. In river and lake fishes, a more gradual decrease and higher radiocesium ((134)Cs, (137)Cs) concentrations were observed than in culture pond fishes, which strongly implied that radiocesium in freshwater fish species was mainly bioaccumulated through the food web in the wild. During 2011-2014, percentages above the Japanese regulatory limit of 100 Bq kg(-1)-wet for radiocesium in river and lake fish (14.0% and 39.6%, respectively) were higher than in monitored marine fish (9.9%), indicating longer-term contamination of freshwater fish species, especially in lakes. Higher radiocesium concentrations (maximum 18.7 kBq kg(-1)-wet in Oncorhynchus masou) were found in the northwestern areas from the FDNPP with higher deposition. However, radiocesium contamination levels were regarded as 1-2 orders of magnitude less than those after the Chernobyl accident. Lagged increase of (137)Cs concentration and longer ecological half-lives (Teco: 1.2-2.6 y in the central part of Fukushima Prefecture) were observed in carnivorous salmonids (O. masou, Salvelinus leucomaenis), whereas a rapid increase and decrease of (137)Cs concentration and shorter Teco (0.99 and 0.69 y) were found in herbivorous and planktivorous osmerids (Plecoglossus altivelis, Hypomesus nipponensis) with younger age at maturity. Comparison of Teco among salmonids, osmerids, and cyprinids suggests that, in addition to the fish feeding habits and life-cycles, hydraulic conditions in rivers and lakes (e.g., turnover time), which are expected to affect radiocesium concentration in prey items, are an important factor affecting the (137)Cs decreasing rate of freshwater fish., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Ayu Plecoglossus altivelis, a herbivorous fish, is an important fishery resource and key component of the foodweb in many Japanese streams. Radionuclide contamination of this species is likely transferred to higher trophic levels, include humans, in the food chain. After the Fukushima accident in March 2011, ayu were exposed to highly contaminated silt while feeding on algae attached to the riverbed stones. To understand the route by which herbivorous fish are exposed to radionuclides, the activity concentrations of sum of (134)Cs and (137)Cs (radiocesium) were analyzed in riverbed samples (algae and silt) and in the internal organs and the muscle of ayu in five river systems in the Fukushima Prefecture between summer 2011 and autumn 2013. Although there was a positive correlation between the radiocesium activity concentrations in the muscle and the internal organs of ayu, the median activity concentration in the muscle was much lower than those in the internal organs. The activity concentrations of radiocesium in the riverbed samples and the internal organs and the muscle of ayu were correlated with contamination levels in soil samples taken from the watershed upstream of the sample sites. The results of the generalized linear mixed models suggest that the activity concentrations in both the internal organs and the muscle of ayu declined over time. Additionally, the activity concentrations in the internal organs were correlated with those in the riverbed samples that were collected around the same time as the ayu. The activity concentrations in the muscle were correlated with ayu body size. Our results suggest that ayu ingest (134)Cs and (137)Cs while grazing silt and algae from the riverbed, and a part of the (134)Cs and (137)Cs is assimilated into the muscle of the fish., (Copyright © 2014 Elsevier Ltd. All rights reserved.)