North Kanto Research Articles

Radiocesium transfer from soil is lower in tall fescue than orchardgrass under conditions of lower soil exchangeable potassium

AbstractIn Japan, additional potassium fertilization is used as a countermeasure for radiocesium‐contaminated grasslands in the Tohoku and North Kanto regions. A 2‐year pot experiment was conducted to assess the efficacy of using tall fescue (Festuca arundinacea Schreb.), a low‐cesium‐absorption grass species, to replace orchardgrass (Dactylis glomerata L.), the most common forage grass species in these regions, to reduce potassium fertilization and improve the forage mineral balance. The treatments were a combination of two grass species (tall fescue and orchardgrass) and two potassium application rates (0 [K0] and three times the conventional amount [K3]) with four replications. The grass species and potassium application rate had significant (p < .001) effects on plant cesium‐137 concentrations. The results of the generalized linear mixed‐model analysis indicated that when tall fescue replaced orchardgrass, cesium‐137 in the forage grass was reduced to 34% and that the K3 treatment reduced cesium‐137 to 46% relative to the K0 treatment. The difference in cesium‐137 concentration between the two grass species increased as the soil exchangeable K2O content decreased. The equations for estimating the cesium‐137 concentration (y [g/kg]) from the exchangeable K2O content (x [g/kg]) were obtained as y = 63.7e–2.095x for tall fescue and y = 185.5e–3.327x for orchardgrass. These equations indicate that tall fescue cultivation can reduce the risk of elevated radioactive Cs in the grass by reducing potassium fertilizer to approximately half that of orchardgrass. There were no differences in the response of plant potassium concentrations or the potassium/(calcium + magnesium) equivalent ratio to soil exchangeable K2O content among the grass species. However, the mineral balance of forage can be improved by reducing potassium fertilizer applications for cesium‐137 remediation. Tall fescue has good potential to remediate contaminated grasslands as it reduces additional potassium fertilization and improves the mineral balance of forage.

Large microsatellite shifts in wild boar after the Fukushima accident

Although nuclear power plant accidents have raised concerns about the genetic consequences of radiation exposure, no studies have successfully compared the DNA of wild animals before and after the accident in the same area around a nuclear power plant. Here, we investigated 12 microsatellites of Japanese wild boar in the Fukushima prefecture before and after the Fukushima Daiichi nuclear accident. A population structure analysis of the microsatellites revealed that wild boar of the 4 prefectures of North Kanto were divided into 5 populations before the nuclear accident. Yet, wild boar sampled after the nuclear accident did not belong to any of these 5 populations. The reason for this result was related to significant changes in the composition of microsatellites after the nuclear accident; on average, 90% of post-accident microsatellite alleles were newly emergent in Fukushima prefecture. In samples obtained before the nuclear accident, each microsatellite had either even or odd-length alleles. Yet, in samples obtained after the nuclear accident, most microsatellites had alleles of both even and odd lengths. Moreover, we examined haplotypes and their frequencies in the mitochondrial DNA control region, and found no significant differences before and after the nuclear accident in both Fukushima and Tochigi prefectures, and no haplotypes were distributed only in distant areas suggesting an influx of wild boar after the nuclear accident. This research suggested that the change in microsatellites was a result of microsatellite instability rather than a result of the migration of wild boar from other areas. This research provides important insights into the effects of a nuclear accident on mammals.

A New Electric Field Mill Network to Estimate Temporal Variation of Simplified Charge Model in an Isolated Thundercloud.

The gross charge distribution in an electrified cloud has already been estimated by polarity distribution of the electrostatic field on the ground surface. While either a dipole or a tripole charge structure is commonly accepted, the increase–decrease and motion of each point charge in those models are both still unclear. This paper presents a new network of electric field mills for multipoint electrostatic measurement to evaluate the temporal variations of a simple cloud charge model with second-scale resolution. Details of our newly developed equipment are described, with an emphasis on its advantages. This network was deployed in the north Kanto area of Japan and operated during the summer season in 2020. In order to simplify the relationship between cloud charge positions and the horizontal distribution of the measured electrostatic field, an isolated thundercloud is focused on. As an initial analysis, a negative point charge model is applied to an isolated cloud observed on 27 August 2020. The quantity and height of the point charge were estimated as being approximately −20 C and 7 km, respectively. The calculated charge location is generally coincident with the C-band radar echo regions. Significant correspondence is demonstrated between the intensity distribution of the electrostatic fields measured at seven sites and that calculated with estimated point charge. This result indicates the possibility to determine the amounts and positions of cloud charges inside the dipole charge structure based on multipoint measurement of the electrostatic field.

South Kanto Block, North Kanto, and Koshinetsu Block Activity Report

South Kanto Block, North Kanto, and Koshinetsu Block Activity Report

Evaluation of tall fescue as a low radiocesium-uptake grass species to replace orchardgrass in Japan

Grasslands in Tohoku and North Kanto, Japan were contaminated with radiocesium released from the Fukushima Dai-ichi Nuclear Power Plant in March 2011. The dominant pasture species in the permanent grasslands of these areas is orchardgrass (Dactylis glomerata L.). Two field studies were conducted to determine the potential of a low radiocesium-uptake forage grass to replace orchardgrass for remediation of contaminated grasslands. From 2012 to 2014, tall fescue (Festuca arundinacea Schreb.) showed lower 137Cs uptake than orchardgrass under harvesting condition. The annual mean 137Cs activity concentration and transfer factor in tall fescue were half of those in orchardgrass. There was no significant difference in the 137Cs activity concentration among the five cultivars of tall fescue at the third harvest in 2012. From 2016 to 2019, another field study was conducted in a pasture with tall fescue and orchardgrass introduced by overseeding under heavy grazing pressure after the Fukushima Dai-ichi Nuclear Power Plant accident. Tall fescue and orchardgrass were collected in May, July, and September from four paddocks before rotational grazing. Three grasses that were originally present, Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and white clover (Trifolium repens L.), were collected each time that tall fescue and orchardgrass were sampled in 2016–2017. They were also collected at the sampling time in May of 2018 and 2019. Tall fescue showed a consistently lower transfer factor than orchardgrass during the four years. Tall fescue had the lowest transfer factor compared with the three originally grown plant species. The Ministry of Agriculture, Forestry and Fisheries of Japan recommends an exchangeable K2O content of 0.3–0.4 g kg−1 in soil (0–15 cm depth) to keep the 137Cs activity concentration in forage grass below the provisional tolerance level for feed. The soil exchangeable K2O content in both field studies was lower than this. Tall fescue is considered a low radiocesium-uptake grass and a potential replacement for orchardgrass in Japan. The use of tall fescue might reduce the amount of potassium fertilizer needed in contaminated grasslands.

Temporal Change in Genetical Lineages of Infectious Hematopoietic Necrosis Virus (IHNV) in the North Kanto Region of Japan from 1981 to 2015

Temporal Change in Genetical Lineages of Infectious Hematopoietic Necrosis Virus (IHNV) in the North Kanto Region of Japan from 1981 to 2015

South Kanto Block, North Kanto, and Koshinetsu Block Activity Report

South Kanto Block, North Kanto, and Koshinetsu Block Activity Report

South Kanto Block, North Kanto, and Koshinetsu Block Activity Report

South Kanto Block, North Kanto, and Koshinetsu Block Activity Report

Efficacy and safety of glecaprevir and pibrentasvir combination therapy in old-aged patients with chronic hepatitis C virus infection.

Objective: Combination therapy with glecaprevir and pibrentasvir (G/P) has been shown to provide a sustained virologic response (SVR) rate of >97% in patients with chronic hepatitis C virus (HCV) infection in the first published real-world Japanese data. However, a recently published study showed that the treatment was often discontinued in patients ≥75 years old, resulting in low SVR in intention-to-treat (ITT) analysis. Thus, our aim was to evaluate real-world data for G/P therapy in patients ≥75 years of age, the population density of which is high in “rural” regions.Patients and Methods: We conducted a multicenter study to assess the efficacy and safety of G/P therapy for chronic HCV infection, in the North Kanto area in Japan.Results: Of the 308 patients enrolled, 294 (95.5%) completed the treatment according to the protocol. In ITT and per-protocol analyses, the overall SVR12 rate was 97.1% and 99.7%, respectively. The old-aged patients group consisted of 59 participants, 56 of whom (94.9%) completed the scheduled protocol. Although old-aged patients tended to have non-SVR factors such as liver cirrhosis, history of HCC, and prior DAA therapies, the SVR12 rates in old-aged patients were 98.3% and 100% in the ITT and PP analyses, respectively. Of 308 patients enrolled, adverse events were observed in 74 patients (24.0%), with grade ≥3 events in 8 patients (2.6%). There was no significant difference in any grade and grade ≥3 adverse events between the old-aged group and the rest of the study participants. Only one patient discontinued the treatment because of adverse events.Conclusion: G/P therapy is effective and safe for old-aged patients.

The Results and Issues of the Farmland Bank in North Kanto Area

The Results and Issues of the Farmland Bank in North Kanto Area

Antimicrobial usage on 72 farrow-to-finish pig farms in Japan from 2015 to 2017

In Japan veterinary antimicrobials are used most in the pig production sector. However, there is a paucity of data on the quantity of antimicrobials used on pig farms in Japan. This study describes antimicrobial use on Japanese pig farms in 2015, 2016 and 2017 in terms of mg of active ingredient per kg of PCU (population correction unit). Data on antimicrobial use from a total of 72 farrow-to finish farms over these three years were used in the study. The results revealed that the average use of antimicrobials in 2015, 2016 and 2017 was 304.8 (SD = 226.3), 311.2 (SD = 241.0) and 342.9 (SD = 291.3) mg/kg PCU, respectively. Most (97%) of the antimicrobials were administered orally. The most commonly used antimicrobials were tetracyclines, followed by macrolides, penicillins and sulfonamides. Tohoku was the region in which the lowest quantities of antimicrobial were used whilst South Kanto was the region in which the largest amount was used. The use of antimicrobials was on the increase in the North Kanto, South Kanto and Kyushu regions.

Investigator-Initiated Registration Directed Trials, or Advanced Medical Care conducted by GOTIC and NRG-Oncology Japan

Abstract NRG Oncology-Japan is a group of Japanese institutions participating in NCI-sponsored academic studies as an international member of NRG Oncology (NRG), which is one of the cancer clinical research groups under NCI. At the same time as conducting investigator-initiated clinical trials for gynecologic cancer, breast cancer and brain tumors, we are developing new drugs for approval application in Japan as investigator-initiated trials. Especially in the gynecologic cancer area, from the GOG era, one of NRG's predecessor groups, we conducted investigator-initiated clinical trials (GOG 218 trial) aiming for approval for ovarian cancer of bevacizumab and work on advanced medicine (GOG 213 trial), and then, chieved approval. Currently, we are conducting both GY004 and GY005 trials as investigator-initiated trials with the aim of approving recurrent ovarian cancer from olaparib and cediranib. GOTIC (North Kanto Gynecologic Cancer Clinical Trials Consortium) is a gynecological cancer clinical trials group (general incorporated corporation) established in 2009. So far, a phase 3 comparative study (iPocc study) to verify the usefulness of intraperitoneal administration of carboplatin has been carried out as an international collaboration study (advanced medical care in Japan) based on AMED funds. In addition, the PAOLA-1 trial aimed at the combined approval of olaparib and bevacizumab for ovarian cancer is being conducted as a doctor-led clinical trial led by GINECO, a gynecological cancer clinical trial group in France. The role of the Study Coordination Center is extremely important for the smooth execution of these physician-led clinical trials and physician-led clinical trials. I would like to introduce the efforts and problems at NRG Japan, GOTIC, focusing on the relationship with the coordinating center.

Reconstruction of a Fukushima accident-derived radiocesium fallout map for environmental transfer studies

Ascertaining the initial amount of accidently released radiocesium is fundamental for determining the extent of radioactive contamination following nuclear accidents, and is of key importance to environmental transfer models. A series of the airborne monitoring surveys of radioactivity have conducted by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), and provide basic information on radioactive contamination following the accident. However, there are no clear guidelines regarding the selection of airborne monitoring survey results for estimating the initial fallout input in studies of the environmental transfer of radiocesium. This study reconstructed a fallout map of Fukushima accident-derived radiocesium based on a comparison of the radiocesium deposition densities (Dl) derived from the third and fifth airborne monitoring surveys. The Dl derived from the fifth airborne monitoring survey were adjusted for variation in the measured radioactivity associated with the influence of radioactive decay, natural weathering processes, variation in the calibration procedure, and other, undefined mechanisms. The calibrated deposition density of the fifth airborne monitoring survey for each land use type (A′5th*l) were used to establish the initial fallout map in the East Japan area. Furthermore, the airborne monitoring surveys which were independently conducted in each prefecture area were used to complement the lack of data in the South Kanto region and the mountainous area in the North Kanto region due to snow cover during the measurement period of the fifth airborne monitoring survey. The reconstructed initial fallout map of the Fukushima accident derived 137Cs was opened to the public via the database of the Center for Research in Isotopes of Environmental Dynamics, University of Tsukuba, Japan (www.ied.tsukuba.ac.jp/∼fukushimafallout/). Finally, the total atmospheric deposition of Fukushima Dai-ichi Nuclear Power Plant accident-derived radiocesium onto each prefecture and land uses was estimated based on the reconstructed map in this study.

人工林再生産過程にみる自然資源管理の歴史性と地域性 : 高原林業地の形成過程より(テーマ:自然資源管理の論点-林業経済研究の視点から-,林業経済学会2016年春季大会)

人工林再生産過程にみる自然資源管理の歴史性と地域性 : 高原林業地の形成過程より(テーマ:自然資源管理の論点-林業経済研究の視点から-,林業経済学会2016年春季大会)

Three important Holocene tephras off the Pacific coast of the Tohoku region, Northeast Japan: Implications for correlating onshore and offshore event deposits

Tephra is a product of explosive volcanic eruptions, and is deposited and preserved in both terrestrial and marine environments. Because a tephra is a geologically synchronous deposit, tephras constitute important isochrones in the Quaternary sequences in and around Japan, and can be used to correlate onshore and offshore events. Tephras are considered to be robust time markers connecting the two environments. For this comparison, it is important to establish a marine tephra catalog. We examined a total of 52 marine cores collected from offshore Fukushima to south of Cape Erimo-misaki, Hokkaido, to identify the Holocene tephras in this region. As a result, 11 tephras were identified and correlated with known late Quaternary tephras. Among them, three Holocene tephras are widespread in this region: the To-a (915 CE) and To-Cu (6 ka) tephras from Towada Caldera, North Tohoku, and the Hr-FP (6th Century) tephra from Haruna Volcano, North Kanto. The To-a tephra is distributed in the southern part of the study area. The Hr-FP tephra has a very narrow distribution, and is only found offshore of the central Sanriku coast. The To-Cu tephra, on the other hand, shows a wider distribution, covering most of the study area. These tephras provide important and robust isochrones for correlating offshore and onshore events along the deep Japan Trench.

スキー場の植生と土壌 : II.水上宝台樹スキー場の場合

スキー場の植生と土壌 : II.水上宝台樹スキー場の場合

Reconsideration of the age of the middle Pleistocene Hoshakuji fluvial terrace in the Kinu River Basin, North Kanto, Japan

Reconsideration of the age of the middle Pleistocene Hoshakuji fluvial terrace in the Kinu River Basin, North Kanto, Japan

The Politics of Migration in Tokugawa Japan: The Eastward Expansion of Shin Buddhism

Between 1790 and 1868, tens of thousands of settlers migrated from Hokuriku to the North Kanto and the Northeast, usually under the active encouragement of local authorities trying to reverse recent population declines. This migration faced formidable obstacles. Governments in Hokuriku often opposed the departure of their subjects, and in the East, many local communities did not want outsiders to settle in their midst. It was primarily networks of temples that bridged these mental moats. That such networks were necessary to enable migration between jurisdictions underlines how exclusive Japan’s local communities remained even in the nineteenth century.

Effects of the Fukushima Daiichi nuclear accident on goshawk reproduction.

Although the influence of nuclear accidents on the reproduction of top predators has not been investigated, it is important that we identify the effects of such accidents because humans are also top predators. We conducted field observation for 22 years and analysed the reproductive performance of the goshawk (Accipiter gentilis fujiyamae), a top avian predator in the North Kanto area of Japan, before and after the accidents at the Fukushima Daiichi nuclear power plant that occurred in 2011. The reproductive performance declined markedly compared with the pre-accident years and progressively decreased for the three post-accident study years. Moreover, it was suggested that these declines were primarily caused by an increase in the air dose rate of radio-active contaminants measured under the nests caused by the nuclear accidents, rather than by other factors. We consider the trends in the changes of the reproductive success rates and suggest that internal exposure may play an important role in the reproductive performance of the goshawk, as well as external exposure.

最終氷期最寒冷期末期の北関東丘陵域における古植生分布─宇都宮市中里の植物化石群からの復元─

最終氷期最寒冷期末期の北関東丘陵域における古植生分布─宇都宮市中里の植物化石群からの復元─