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1.
Medicine (Baltimore) ; 100(6): e24177, 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33578521

RESUMO

ABSTRACT: We had earlier reported about the increase in the prevalence of atrial fibrillation (AF) among residents in the evacuation zone of Fukushima Prefecture after the Great East Japan Earthquake. In the present investigation, we explored the association between the prevalence of AF and white blood cell (WBC) count after the earthquake through an observational cross-sectional study.A total of 14,800 participants (6427 men and 8373 women) were included in the Fukushima Health Management Survey. For the present study, 12-lead electrocardiogram tracings and the WBC count and its subtypes were obtained and analyzed. The odds ratios (ORs) of AF after the earthquake and the 95% confidence intervals (CIs) for one standard deviation of differential WBC count were calculated after adjustments for age and other potential confounding factors using the logistic regression model.Our results revealed a prevalence of AF of 1.8% (269 participants) after the earthquake. Monocyte count and neutrophil/lymphocyte ratio exhibited a significant association with the prevalence of AF in the multivariable-adjusted model. The adjusted ORs of monocyte count and neutrophil/lymphocyte ratio for AF were 1.21 (95% CI, 1.05-1.40, P = .01) and 1.22 (95% CI, 1.01-1.44, P < .05), respectively.The prevalence of AF was associated with increased monocyte count and neutrophil/lymphocyte ratio among residents in the evacuation zone in Fukushima Prefecture, suggesting that inflammation and psychological stress could be important factors mediating the development of AF after the earthquake.


Assuntos
Fibrilação Atrial/sangue , Fibrilação Atrial/epidemiologia , Terremotos/estatística & dados numéricos , Contagem de Leucócitos/estatística & dados numéricos , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/fisiopatologia , Estudos Transversais , Eletrocardiografia/métodos , Feminino , Acidente Nuclear de Fukushima , Inquéritos Epidemiológicos , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Prevalência , Estresse Psicológico/epidemiologia
2.
Am J Nurs ; 121(2): 63-67, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33497131

RESUMO

ABSTRACT: The release of radioactive iodine after a nuclear disaster, such as those that occurred at the Fukushima Daiichi Nuclear Power Plant in Japan 10 years ago and Three Mile Island in Pennsylvania in 1979, increases thyroid cancer risk among people who are exposed. Certain populations are especially vulnerable, including pregnant and breastfeeding women, children, and neonates. Potassium iodide (KI) can effectively block radioactive iodine from being absorbed by the thyroid gland if taken immediately after a radiation release. This article examines lessons learned from Fukushima to enhance disaster readiness and nursing actions. Nurses should be directly involved in vulnerability assessments, emergency planning, and in ensuring the availability, accessibility, and distribution of KI within U.S. nuclear power plant emergency planning zones before a crisis occurs.


Assuntos
Acidente Nuclear de Fukushima , Iodeto de Potássio/uso terapêutico , Exposição à Radiação/prevenção & controle , Exposição Ambiental/prevenção & controle , Humanos , Japão , Iodeto de Potássio/farmacologia , Neoplasias da Glândula Tireoide/tratamento farmacológico , Neoplasias da Glândula Tireoide/prevenção & controle
3.
Sci Total Environ ; 763: 142946, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33498123

RESUMO

Despite many studies carried out to date, the long-term effects of chronic exposure on plants and animals inhabiting the territories affected by the Fukushima Dai-Ichi NPP accident remain the subject of scientific discussions. Our investigations were performed on Japanese red pine, the native tree species that is widely spread in the radioactive contaminated areas. Earlier observations revealed the radiation-induced cancellation of the apical dominance in young trees of this species. To understand the mechanism of such transformation, we evaluated the morphometric parameters of needles, the frequency of cytogenetic abnormalities, and the concentrations of the major classes of phytohormones in several natural populations of young red pine trees growing under different exposure conditions in Fukushima prefecture. No significant relationships between the morphometric parameters of needles and dose rates at the experimental sites were revealed. The frequencies of aberrant cells in the needle's intercalary meristem and the frequencies of cancellation of the apical dominance in the young pine populations in the radioactive contaminated areas were significantly higher than in the reference population. However, only cytogenetic abnormalities increased with the dose rate. We have not found the relation between the frequency of cytogenetic abnormalities in needles and cancellation of the apical dominance in the individual trees. In this paper, for the first time, it is shown that chronic radiation exposure changes the concentration ratio of the major classes of phytohormones in the needles of Japanese red pine. Given the complete lack of information about the most important regulatory system of plants in chronically irradiated populations, this study fills a substantial gap in our knowledge. Finally, our findings indicated that the most probable causes of the cancellation of apical dominance observed in chronically exposed Japanese red pines are radiation damage to the apical meristems of the trees and changes in their phytohormonal balance.


Assuntos
Acidente Nuclear de Fukushima , Pinus , Exposição à Radiação , Monitoramento de Radiação , Animais , Radioisótopos de Césio/análise , Japão
4.
Water Res ; 188: 116514, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33075597

RESUMO

We analyzed mid- to long-term 137Cs wash-off from the catchments contaminated due to the Chernobyl accident in 1986 and the Fukushima Dai-ichi Nuclear Power Plant accident in 2011. A semi-empirical diffusional model for radionuclide wash-off is proposed to enable estimation of the dissolved and particulate 137Cs wash-off ratios for the Chernobyl and Fukushima contaminated catchments; the differences in the wash-off characteristics for these two regions are explained and their long-term trends predicted. The model is based on the premise that the catchment topsoil layer is the source of sediments in the rivers, and the radionuclide concentration in the topsoil can be described by a simple diffusion equation. The particulate 137Cs wash-off ratios for the Fukushima contaminated catchments appear to be comparable or slightly lower than those for Chernobyl. The dissolved 137Cs wash-off ratios for Fukushima catchments are at least an order of magnitude lower than those for Chernobyl, mainly due to an order of magnitude difference in the 137Cs distribution coefficients for the Fukushima and Chernobyl rivers. The proposed semi-empirical diffusional model for radionuclide wash-off satisfactorily describes the temporal trends in the 137Cs wash-off characteristics for both the Chernobyl and Fukushima cases, and can be used as a tool for predicting 137Cs wash-off after a nuclear accident.


Assuntos
Acidente Nuclear de Chernobyl , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos da Água , Radioisótopos de Césio/análise , Japão , Rios , Poluentes Radioativos da Água/análise
5.
J Environ Radioact ; 227: 106508, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33338867

RESUMO

In a previous study in 2016, we presented how 129I in coral cores from the east (Baler) and west (Parola) sides of the Philippines recorded the impacts of human nuclear activities, including nuclear weapons testing, nuclear fuel reprocessing, and nuclear accidents. However, the 2016 Baler dataset only had a two-year time resolution and a crude age model based on growth band counting. Here we present a new 2020 Baler 129I/127I atomic ratio dataset that features at least annual time resolution and a more accurate age model constructed using 3D X-ray Computed Tomography. Results show that the bomb peaks in Baler primarily came from the Pacific Proving Grounds or PPG with a time lag of about 1.8 years (or more specifically, between 1.3 and 2.4 years). Moreover, a review of the Parola dataset shows that PPG signals may have been transported to Parola in the West Philippine Sea via two pathways: the northward and southward bifurcations of the North Equatorial Current, reaching Parola about 4.5 and 8.5 years after detonation, respectively. Moreover, a prominent peak in the year 2014.7 in Baler possibly came from the 2011 Fukushima Accident, transported by the Kuroshio Recirculation Gyre and the North Pacific Mode Waters with a 3.5-year time lag. This study contributes to the understanding of the impact and transport of human-made radionuclides to the Philippines and the relevant oceanographic processes in the Western Equatorial Pacific region.


Assuntos
Antozoários , Acidente Nuclear de Fukushima , Radioisótopos do Iodo/análise , Monitoramento de Radiação , Poluentes Radioativos da Água , Animais , Humanos , Filipinas , Poluentes Radioativos da Água/análise
6.
Sci Total Environ ; 754: 141890, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32916482

RESUMO

Plutonium (Pu) has been released in Japan by two very different types of nuclear events - the 2011 Fukushima accident and the 1945 detonation of a Pu-core weapon at Nagasaki. Here we report on the use of Accelerator Mass Spectrometry (AMS) methods to distinguish the FDNPP-accident and Nagasaki-detonation Pu from worldwide fallout in soils and biota. The FDNPP-Pu was distinct in local environmental samples through the use of highly sensitive 241Pu/239Pu atom ratios. In contrast, other typically-used Pu measures (240Pu/239Pu atom ratios, activity concentrations) did not distinguish the FDNPP Pu from background in most 2016 environmental samples. Results indicate the accident contributed new Pu of ~0.4%-2% in the 0-5 cm soils, ~0.3%-3% in earthworms, and ~1%-10% in wild boar near the FDNPP. The uptake of Pu in the boar appears to be relatively uninfluenced by the glassy particle forms of fallout near the FDNPP, whereas the 134,137Cs uptake appears to be highly influenced. Near Nagasaki, the lasting legacy of Pu is greater with high percentages of Pu sourced from the 1945 detonation (~93% soils, ~88% earthworm, ~96% boar). The Pu at Nagasaki contrasts with that from the FDNPP in having proportionately higher 239Pu and was distinguished by both 240Pu/239Pu and 241Pu/239Pu atom ratios. However, compared with the contamination near the Chernobyl accident site, the Pu amounts at all study sites in Japan are orders of magnitude lower. The dose rates from Pu to organisms in the FDNPP and Nagasaki areas, as well as to human consumers of wild boar meat, have been only slightly elevated above background. Our data demonstrate the greater sensitivity of 241Pu/239Pu atom ratios in tracing Pu from nuclear releases and suggest that the Nagasaki-detonation Pu will be distinguishable in the environment for much longer than the FDNPP-accident Pu.


Assuntos
Acidente Nuclear de Fukushima , Plutônio , Monitoramento de Radiação , Cinza Radioativa , Poluentes Radioativos da Água , Animais , Biota , Radioisótopos de Césio/análise , Japão , Plutônio/análise , Cinza Radioativa/análise , Suínos , Poluentes Radioativos da Água/análise
7.
J Environ Radioact ; 226: 106456, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33217723

RESUMO

Understanding the relationship between the distribution of radioactive 134Cs and 137Cs in forests and ambient dose equivalent rates (H˙∗(10)) in the air is important for researching forests in eastern Japan affected by the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. This study used a large number of measurements from forest samples, including 134Cs and 137Cs radioactivity concentrations, densities and moisture contents, to perform Monte Carlo radiation transport simulations for H˙∗(10) between 2011 and 2017. Calculated H˙∗(10) at 0.1 and 1 m above the ground had mean residual errors of 19% and 16%, respectively, from measurements taken with handheld NaI(Tl) scintillator survey meters. Setting aside the contributions from natural background radiation, 134Cs and 137Cs in the organic layer and the top 5 cm of forest soil generally made the largest contributions to calculated H˙∗(10). The contributions from 134Cs and 137Cs in the forest canopy were calculated to be largest in the first two years following the accident. Uncertainties were evaluated in the simulation results due to the measurement uncertainties in the model inputs by assuming Gaussian measurement errors. The mean uncertainty (relative standard deviation) of the simulated H˙∗(10) at 1 m height was 11%. The main contributors to the total uncertainty in the simulation results were the accuracies to which the 134Cs and 137Cs radioactivities of the organic layer and top 5 cm of soil, and the vertical distribution of 134Cs and 137Cs within the 5 cm soil layers, were known. Radioactive cesium located in the top 5 cm of soil was the main contributor to H˙∗(10) at 1 m by 2016 or 2017 in the calculation results for all sites. Studies on the 137Cs distribution within forest soil will therefore help explain radiation levels henceforth in forests affected by the FDNPP accident. The merits of this study are that it modelled multiple forests for a long time period, with the important model inputs being informed by field measurements, and it quantified how the measurement uncertainties in these inputs affected the calculation results.


Assuntos
Radioisótopos de Césio/análise , Florestas , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Japão , Radioatividade
8.
J Environ Radioact ; 226: 106457, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33227677

RESUMO

Radiocesium was dispersed from the Fukushima Dai-ichi disaster in March 2011, causing comparatively high radioactive contamination in nearby environments. Radionuclide concentrations in wild rodents (Apodemus argenteus, and Apodemus speciosus) within these areas were monitored from 2012 to 2016. However, whole-organism to soil transfer parameters (i.e., concentration ratio, CRwo-soil) for wild rodents at Fukushima were not determined and hence were lacking from the international transfer databases. We augmented the 2012-2016 data by collecting soil activity concentrations (Bq kg-1, dry mass) from five rodent sampling sites in Fukushima Prefecture, and developed corresponding CRwo-soil values for radiocesium (134Cs and 137Cs) based on rodent radioactivity concentrations (Bq kg-1, fresh mass). The CRwo-soil were added to the Wildlife Transfer Database (WTD; http://www.wildlifetransferdatabase.org/), supporting the development of the International Commission on Radiological Protection's (ICRP) environmental protection framework, and increasing the WTD from 84 to 477 entries for cesium and Muridae ('Reference Rat'). Significant variation occurred in CRwo-soil values between study sites within Fukushima Prefecture. The geometric mean CRwo-soil, in this paper, was higher than that reported for Muridae species for Chernobyl. Radiocaesium absorbed dose rates were also estimated for wild rodents inhabiting the five Fukushima study sites and ranged from 1.3 to 33 µGy h-1. Absorbed dose rates decreased by a factor of two from 2012 to 2016. Dose rates in highly contaminated areas were within the ICRP derived consideration reference level for Reference Rat (0.1-1 mGy d-1), suggesting the possible occurrence of deleterious effects and need for radiological effect studies in the Fukushima area.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Poluentes Radioativos da Água/análise , Animais , Radioisótopos de Césio/análise , Japão , Doses de Radiação , Ratos
9.
Sci Total Environ ; 750: 142311, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182179

RESUMO

Since Fukushima accident, dozens of field studies have been conducted in order to quantify and understand the behaviour of atmospheric radiocesium (137Cs) fallouts in contaminated forests of Fukushima and neighbouring prefectures. In this paper, we carry out a detailed review of data acquired over 2011-2017 in Japanese cedar and cypress plantations, focusing on aerial tree organs, soil layers and tree-to-soil depuration fluxes. To enable comparison and reinforce the consistency between sites, radiological measurements were normalized by the deposit and interpolated onto the same spatio-temporal frame. Despite some (poorly explained) residual variability, we derived a "mean" pattern by log-averaging data among sites. These "mean" results were analysed with the help of a simple mass-balance approach and discussed in the light of post-Fukushima literature. We demonstrated that the activity levels and dynamics in all compartments were consistent and generally well reproduced by the mass balance approach, for values of the interception fraction between 0.7 and 0.85. The analysis indicated that about 5% of the initial deposit remained in the aerial vegetation after 6 years, more than two thirds of intercepted 137Cs being transferred to the soil due to throughfall. The simulations indicated that foliar uptake might have contributed between 40% and 100% to the activity transferred to stem wood. The activity concentration in canopy organs rapidly decreased in the first few months then more slowly, according to an effective half-life of about 1.6 years. The activity level in the organic layer peaked in summer 2011 then decreased according to an effective half-life of 2.2 years. After a rapid increase in 2011, the contamination of mineral horizons continued to increase more slowly, 85% of 137Cs incoming through the organic layer being retained in the 0-5 cm layer according to a mean residence time longer than in the upper layer (7 against 1.5 years).


Assuntos
Cryptomeria , Cupressus , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo , Radioisótopos de Césio/análise , Florestas , Japão , Poluentes Radioativos do Solo/análise
10.
Artigo em Inglês | MEDLINE | ID: mdl-33352668

RESUMO

Objective: The Fukushima Daiichi nuclear disaster in 2011 produced psychological reactions among evacuees. Despite the harsh situation, subsequently, there has been gradual progress in reconstruction, with more than half of the evacuees returning after the evacuation. Our hypothesis is that evacuee mental health will now be better due to new stable living conditions. This study aims to clarify the statuses of psychological distress, post-traumatic stress, and radiation health anxiety among evacuees who have rebuilt permanent homes after evacuation. Methods: A cross-sectional questionnaire survey of 1600 residents was conducted in 2020. As primary outcomes, the survey measured psychological distress (Kessler 6), post-traumatic stress (post-traumatic stress four-item checklist), and radiation health anxiety. The data are compared for residents who have rebuilt permanent home and those who did not evacuate. Results: In the co-variant analysis, the statuses of psychological distress (p < 0.001), post-traumatic stress (p < 0.001), and radiation health anxiety (p < 0.001) are found to still be high, with significant differences when compared to those who did not evacuate. These results are still at an equivalent level for the continuing evacuation. Conclusion: Our findings may indicate a necessity for continuing disaster-related mental health activities even though the living conditions have improved.


Assuntos
Transtornos Relacionados ao Uso de Álcool/epidemiologia , Ansiedade/epidemiologia , Acidente Nuclear de Fukushima , Angústia Psicológica , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Estresse Psicológico/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Desastres , Terremotos , Feminino , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Radiação , Inquéritos e Questionários , Adulto Jovem
11.
Sci Data ; 7(1): 433, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33319799

RESUMO

Radiocesium released from the Fukushima Daiichi nuclear power plant (FDNPP) and deposited in the terrestrial environment has been transported to the sea through rivers. To study the long-term effect of riverine transport on the remediation process near the FDNPP, a monitoring project was initiated by the University of Tsukuba. It was commissioned by the Ministry of Education, Culture, Sports, Science, and Technology, and the Nuclear Regulatory Commission in June 2011, and was taken over by the Fukushima Prefectural Centre for Environmental Creation from April 2015. The activity concentration and monthly flux of radiocesium in a suspended form were measured in the project. This provides valuable measurement data to evaluate the impact of the accidentally released radiocesium on residents and the marine environment. It can also be used as verification data in the development and testing of numerical models to predict future impacts.


Assuntos
Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Rios/química , Poluentes Radioativos da Água/análise , Monitoramento Ambiental , Japão , Centrais Nucleares
12.
Sci Data ; 7(1): 431, 2020 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-33339821

RESUMO

The majority of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered with forests. We developed a dataset for radiocaesium (137Cs) in trees, soil, and mushrooms measured at numerous forest sites. The 137Cs activity concentration and inventory data reported in scientific journal papers written in English and Japanese, governmental reports, and governmental monitoring data on the web were collated. The ancillary information describing the forest stands were also collated, and further environmental information (e.g. climate) was derived from the other databases using longitude and latitude coordinates of the sampling locations. The database contains 8593, 4105, and 3189 entries of activity concentration data for trees, soil, and mushrooms, and 471 and 3521 entries of inventory data for trees and soil, respectively, which were collected from 2011 to 2017, and covers the entire Fukushima prefecture. The data can be used to document and understand the spatio-temporal dynamics of radiocaesium in the affected region and to aid the development and validation of models of radiocaesium dynamics in contaminated forests.


Assuntos
Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Poluentes Radioativos do Solo/análise , Agaricales/química , Monitoramento Ambiental , Florestas , Japão , Solo/química , Análise Espaço-Temporal , Árvores/química
13.
PLoS One ; 15(12): e0243367, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33378404

RESUMO

It has been almost 10 years since the accident at Tokyo Electric Power Co., Inc.'s Fukushima Daiichi Nuclear Power Plant in March 2011. This study elucidates changes in the mental states of mothers and children residing in low-dose radiation contaminated regions within Fukushima Prefecture over a five-year period after the Fukushima Daiichi accident. From 2011 to 2015, questionnaire surveys assessing psychological symptoms, including posttraumatic stress disorder-related responses, depressive responses, and stress responses, and radiation protection behaviors were conducted with 18,741 mothers of children aged four, 18, and 42 months. Mothers' and children's psychological symptoms and mothers' radiation protection behaviors were highest in 2011, immediately following the nuclear accident, but decreased over time. However, even in 2015, psychological symptoms and radiation protection behaviors were higher for children and mothers within Fukushima Prefecture than for those in a control group living in regions outside the area, which were minimally affected by the accident. The results suggest that the psychological effects in mothers and children living in low-dose radiation contaminated areas continued for at least five years after the accident. Furthermore, psychological effects in children born after the incident were likely to have been triggered by the parental behavior of mothers who were negatively affected by anxiety and stress. This finding raises concerns regarding the accident's long-lasting psychological effects in mothers and children living in low-contamination regions.


Assuntos
Ansiedade , Depressão , Acidente Nuclear de Fukushima , Saúde Mental , Exposição à Radiação/efeitos adversos , Transtornos de Estresse Pós-Traumáticos , Estresse Psicológico , Adulto , Ansiedade/epidemiologia , Ansiedade/psicologia , Criança , Pré-Escolar , Depressão/epidemiologia , Depressão/psicologia , Feminino , Humanos , Lactente , Japão , Masculino , Pessoa de Meia-Idade , Mães/psicologia , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Transtornos de Estresse Pós-Traumáticos/psicologia , Estresse Psicológico/epidemiologia , Estresse Psicológico/psicologia
14.
J Environ Radioact ; 223-224: 106388, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32868095

RESUMO

Radioactive caesium was released during the accident of Fukushima Dai-ichi nuclear power plant (FDNPP) into the surrounding environment. In the current work, radiocaesium micro-particles (CsMPs) and radiocaesium-rich soil particles were selectively separated from soil particles as well as from each other using autoradiography-based procedure. The applied separation scheme is based on water dilution followed by drying of the soil sample prior to imaging plate autoradiography. The SEM/EDS investigation of the individual CsMPs showed that these particles have a silicate glass structure and vary in shape with a diameter less than 10 µm. For the first time, a two-stage formation mechanism was suggested for a CsMP based on shape and structure heterogeneity of its two parts. Perfect spherical core might be formed in the first stage with a remarkable lower content of Al, and relatively higher concentrations of Si and K than an outer angulated structure, which might be attached to the core sphere during a late stage. The radiocaesium-rich soil particles have bigger size than CsMPs and have a plate-like structure with cleavages inside the grains, which suggest that these particles might be a weathered biotite. The average radioactivity ratio of 134Cs/137Cs (dated March 11, 2011) in the investigated particles was found to be 1.05 ± 0.01, which confirmed that the radiocaesium in CsMPs and in the contaminated soil particles has the same source of origin, which could be unite 3 of FDNPP.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio/análise , Japão , Centrais Nucleares , Solo , Poluentes Radioativos do Solo/análise
15.
J Environ Radioact ; 223-224: 106373, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32873399

RESUMO

After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, immediate soil and vegetation sampling were conducted according to the action plan of nuclear emergency monitoring; however, analysing the monitoring dataset was difficult because the sampling protocols were not standardised. In this study, the sampling protocols applied just after the FDNPP accident were reviewed, and the monitoring data were analysed. The detailed protocols and results can provide a sound basis for guidelines of soil and vegetation sampling for nuclear emergency monitoring. The activity concentrations of 137Cs and 131I in weed samples measured immediately after the FDNPP accident were related to the air dose rate at 1 m. Consequently, vegetation sampling is recommended when the additional dose rate (above background) is higher than 0.1 µSv/h. To enhance the efficiency of a protective response in the case of a nuclear accident, predetermined sampling points for soil and vegetation sampling should be considered in the preparedness plan for nuclear emergencies. Furthermore, sampling and analytical measurement capacities (time, people, cost) during the early phase after nuclear emergencies need to be considered in the preparedness and action plan, and sampling and measurement exercises are highly recommended.


Assuntos
Defesa Civil , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio/análise , Japão , Centrais Nucleares , Solo , Poluentes Radioativos do Solo/análise
16.
J Environ Radioact ; 222: 106307, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892894

RESUMO

In Japan, the radiocesium activity concentration in milk must be less than 50 Bq/kg-fresh to meet shipping standards, and the radiocesium concentration of the diet fed to dairy cattle must be less than 500 Bq/kg-dry. After the Fukushima nuclear accident in 2011, we conducted two experiments to investigate whether Prussian blue (PB) could suppress the radiocesium (134Cs + 137Cs) activity concentration in Japanese cattle' milk. In experiment 1, four cattle were fed a diet with a radiocesium activity concentration of 175 Bq/kg-dry, with or without PB supplementation. The PB intake ranged from 0 to 3.0 g/day, and the average radiocesium intake was 3.42 kBq/day in all treatments. The radiocesium activity concentration in milk decreased from 16.4 to 8.6 Bq/kg-fresh, and the transfer coefficient of radiocesium from diet to milk (Fm) decreased from 4.77 × 10-3 to 2.61 × 10-3 with increased PB intake. In experiment 2, three cattle were fed another diet including a radiocesium activity concentration of 927 Bq/kg-dry of with or without PB supplementation. The PB intake ranged from 0 to 18.9 g/day, and the average radiocesium intake was 15.2 kBq/day in all treatments. The milk's radiocesium activity concentration decreased from 24.3 to 4.2 Bq/kg-fresh, and the Fm decreased from 1.68 × 10-3 to 0.28 × 10-3 with increased PB intake. Our results suggest that both the radiocesium activity concentration in milk and Fm can be reduced by PB, and that Fm is affected by diet. We recommend cattle should be fed absorbents such as PB to minimize the risk of milk radiocesium activity concentration exceeding 50 Bq/kg-fresh even if the diet has a radiocesium activity concentration of less than 500 Bq/kg-dry.


Assuntos
Radioisótopos de Césio , Acidente Nuclear de Fukushima , Leite , Monitoramento de Radiação , Animais , Bovinos , Radioisótopos de Césio/análise , Dieta , Ferrocianetos , Japão , Leite/química
17.
J Environ Radioact ; 222: 106348, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892904

RESUMO

This study examined the temporal variations in radiocesium concentration associated with sinking particles in the northeastern Japan Sea between September 2010 and July 2012. We analyzed sediment trap samples from this period after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011. Cesium-134 was detected in samples collected between May and July 2011 at a depth of 1100 m (4.2-11 mBq g-dry-1) but not in other periods at 1100 m or deeper (3100 and 3500 m). These results confirmed the deposition of FDNPP-derived radiocesium on the surface water in the late April 2011, which rapidly sank with sinking particles to a depth of at least 1100 m, in the northeastern Japan Sea, about 40 days after the deposition in the North Pacific. If FDNPP-derived 137Cs was excluded, no seasonal changes were detected in the 137Cs activity concentration of the sinking particles, and the 137Cs activity concentration of the particles increased with increasing depth. Judging from the concentration of 137Cs of sinking particle and seasonal variation of total mass flux and organic matter content, the lithogenic particle seems to be important for radiocesium associated with sinking particles. These data also strongly suggest a difference in sinking features of particles between 2010-2011 and 2011-2012 deployments. Due to the existence of benthic front, shallow water (1100 m) and deep water (3500 m) are separated during 2010-2011 deployment, but in the winter of 2011-2012, this front disappeared and the particles in surface water seem to have sunk to the depth of 3100 m. The sinking velocity of the particles at 1100 m was estimated to be 33-62 m day-1, with a mean sinking velocity of 43 m day-1. These values were comparable to those estimated at depths shallower than 1000 m in the North Pacific after the FDNPP accident, or in the Mediterranean, North, and Black Seas after the Chernobyl accident.


Assuntos
Radioisótopos de Césio , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos da Água , Mar Negro , Radioisótopos de Césio/análise , Japão , Centrais Nucleares
18.
J Environ Radioact ; 223-224: 106409, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32920309

RESUMO

We studied seasonal changes in radiocesium (137Cs) activity and potassium concentrations in current-year leaves and branches of Pinus densiflora (naturally regenerated saplings), Cryptomeria japonica (planted saplings) and Quercus serrata (planted saplings and coppice shoots) in Fukushima, Japan. We collected current-year shoots from 10 individuals of each species over two growing seasons at intervals of 1-4 months, between June 2016 and December 2017. For the deciduous species Q. serrata, we also collected dead leaves that remained attached to branches in December to investigate reabsorption of 137Cs. All collected shoots were divided into leaves and branches, oven-dried, and ground; dry weights of each sample were recorded. 137Cs activity concentrations were measured using a germanium semiconductor detector. Potassium concentrations were quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). Increases in dry weight were observed in both leaves and branches between May/June and August; growth then slowed considerably and virtually ceased after October. Clear seasonal changes in 137Cs activity concentrations were observed in both 2016 and 2017, regardless of tree species. Concentrations were higher in young leaves and branches during May and June, then decreased and changed relatively little from August to winter. Reduced 137Cs activity concentrations in dead leaves of Q. serrata were observed only in December 2017 (approximately 15% lower than in October). This reduction may indicate reabsorption of 137Cs in leaves prior to shedding. The changes in potassium concentrations were similar to those in 137Cs in both years. Potassium concentrations were higher in young leaves than in mature leaf and branch samples collected later in the year. A reduction of about 50% in the potassium concentrations in dead leaves of Q. serrata was also observed in December. A positive relationship between 137Cs and potassium concentrations in leaves and branches was observed in all species, except for planted Q. serrata. This relationship may indicate that 137Cs moves in tree shoots with potassium. Leaf and branch weight correlated negatively with 137Cs and potassium concentrations. Reduced concentrations may indicate dilution of these elements as a result of biomass increases over the growing season. Our results imply that irrespective of species, 137Cs exhibits seasonal variations resulting from dilution; these variations correspond with trends in potassium, with higher levels in young organs and decreased levels in older organs.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio/análise , Japão , Folhas de Planta/química , Potássio , Estações do Ano , Árvores
19.
J Environ Radioact ; 223-224: 106382, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32916431

RESUMO

The spatial variations of low-level 134Cs concentrations (activities) in seawater off the Japanese Archipelago, particularly in the eastern East China Sea (ECS), in 2018 and 2019 were examined. The 134Cs concentrations, decay-corrected to the date of the Fukushima Dai-ichi Nuclear Power Plant accident, in seawaters were 0.5-2.0 mBq/L. High 134Cs concentrations (1.1-2.0 mBq/L) of the Kuroshio Current subsurface water (densities of 25-26σθ) in the eastern ECS could indicated the contribution of the subtropical mode water from the Pacific Ocean side, and total column inventories were 330-426 Bq/m2. In contrast, as indicated by the same 134Cs concentration level at the surface of the eastern ECS and Sea of Japan, larger portions of the subsurface waters remained in the ECS and Yellow Sea side in response to the existence of the shallow Tsushima Strait.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos da Água , Radioisótopos de Césio/análise , Japão , Oceano Pacífico , Água do Mar , Poluentes Radioativos da Água/análise
20.
J Environ Radioact ; 223-224: 106417, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32911272

RESUMO

Cesium is an element that belongs to the same group as K, and is known to show similar behaviour to that of K in plants. In this study, we conducted a serial leaching test for 120 h to compare the leaching characteristics of dissolved 137Cs and K in forest litter, obtained from Japanese cedar and deciduous broadleaf forests located 40 km from the site of the 2011 Fukushima Dai-ichi nuclear power plant accident. The litter was collected in 2018 and was divided into three groups according to the decomposition level. The cumulative leachable fraction of 137Cs at 120 h ranged from 0.3% to 3.3%, suggesting that most of the 137Cs in the litter was hardly leachable in water. The leachable fraction of 137Cs generally decreased with the decomposition level of the litter, implying that the easily leachable 137Cs eluted into the water during the first stage of decomposition. Meanwhile, the cumulative leachable fraction of K at 120 h was approximately 10 times greater than that of 137Cs and ranged from 22.7% to 54.8%. The leaching speeds of 137Cs and K decreased suddenly with elapsed time regardless of the tree species, decomposition degree, or element. Our findings contribute to the long-term understanding of the 137Cs cycle in forest ecosystems.


Assuntos
Cryptomeria , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio/análise , Ecossistema , Florestas , Japão , Potássio , Poluentes Radioativos do Solo/análise
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