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3.
Medicine (Baltimore) ; 99(1): e18486, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31895781

RESUMO

We have been examining the Comprehensive Health Check of the Fukushima Health Management Survey of residents of 13 municipalities who were forced by the government to evacuate due to the 2011 Great East Japan Earthquake (GEJE). Our findings showed that evacuation is a risk factor for polycythemia and suggested that experiencing an unprecedented disaster and exposure to chronic stress due to evacuation might be a cause of polycythemia.We analyzed the relationship between the prevalence of polycythemia and the following factors observed in the Mental Health and Lifestyle Survey in an observational study with a cross-sectional design: traumatic symptoms, depression status, socioeconomic factors such as residential environment, and working situation after the GEJE. Target population of the survey included men and women who were at least 15 years of age and who lived in the evacuation zones specified by the government. Participants analyzed consisted of 29,474 persons (12,379 men and 16,888 women) who had participated in both the 2011 Comprehensive Health Check and Mental Health and Lifestyle Survey from June 2011 through March 2012.The prevalence of polycythemia was not associated with mental states associated with traumatic symptoms (Post-Traumatic Stress Disorder Checklist Scale ≥ 44) and depression status (Kessler 6-item Scale ≥ 13). Furthermore, multivariate analysis showed that there was a tendency for males to develop polycythemia, with characteristics such as being aged 65 years and older, highly educated, obese (body mass index ≥ 25), hypertensive, diabetic, having liver dysfunction, and a smoker being significantly related to the prevalence of polycythemia.Our findings conclusively demonstrated that polycythemia was not significantly related to psychological factors, but was significantly related to the onset of lifestyle-related disease after the GEJE.


Assuntos
Acidente Nuclear de Fukushima , Policitemia/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Causalidade , Comorbidade , Terremotos , Feminino , Humanos , Japão/epidemiologia , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Policitemia/etiologia , Policitemia/psicologia , Prevalência , Tsunamis , Adulto Jovem
4.
Chemosphere ; 239: 124777, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31518924

RESUMO

The effects of a 50% forest thinning intensity on Fukushima-derived 137Cs deposition by litterfall and its discharge by runoff in hillslope coniferous forest were monitored using four litterfall traps and a hillslope erosion plot. The observation was underway during the pre-and post-thinning periods. Results demonstrated that during the pre-thinning period a total 150 ±â€¯13 g m-2 of litterfall deposited about 924 ±â€¯69 Bq m-2 of 137Cs. This accounts for 11% of the local 137Cs fallout recorded for the study site in the aftermath of the accident. After thinning, both litterfall and 137Cs increased by more than six- and two-fold, respectively. This is possibly owing to the slow individual tree recovery rate assisted by the change on the running space provided by canopy openings, which can accelerate even the normal gust wind to gain damaging power on the unshielded mechanically injured parts of the contaminated residual trees. In both cases, litterfall generally transferred about 37% (3 ±â€¯0.2 kBq m-2) of the local 137Cs fallout onto the forest floor over the observation period. The eroded litter-associated 137Cs increased by about a factor of two after thinning, which only accounted for less than 1% of 137Cs deposited by litterfall. This implies that the forest floor retains 137Cs and remains contaminated regardless of the size of the eroded litter material. But this could become a potential secondary contamination source for the downstream resources such as water bodies and villages, especially at the time of flooding, which in turn calls a serious attention in designing decontamination schemes.


Assuntos
Radioisótopos de Césio/análise , Florestas , Acidente Nuclear de Fukushima , Folhas de Planta/química , Poluentes Radioativos do Solo/análise , Japão , Monitoramento de Radiação , Traqueófitas , Árvores
5.
Chemosphere ; 239: 124783, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726517

RESUMO

This research concerned radioactivity of lichens and mosses from coastal zones of the Canadian Arctic and Alaska. Over 50 samples were collected from 7 positions during two scientific expeditions in 2012 and 2013. The tundra contamination caused by anthropogenic radionuclides was relatively low, reaching mean values with SD's of: 17.4 ±â€¯3.5 Bq/kg for 90Sr, 14.0 ±â€¯2.9 Bq/kg for 134Cs, 38.4 ±â€¯7.5 Bq/kg for 137Cs, 0.86 ±â€¯0.24 Bq/kg for 239+240Pu, 0.065 ±â€¯0.017 Bq/kg for 238Pu and 0.50 ±â€¯0.13 Bq/kg for 241Am. The increase of activity concentration with increasing latitudes was noticed mostly in regard to 90Sr, Pu isotopes and 241Am. The analysis of isotopic ratios exhibited dominant contribution of the global fallout (+SNAP 9A satellite re-entry fallout) for the presence of plutonium isotopes and 241Am. The Fukushima fallout signature was identified in a few lichens from Alaska. However, the influence of additional unknown factor on the occurrence of 90Sr and 137Cs has been detected in western part of Canadian Arctic. Natural radioisotopes of thorium and uranium were found throughout the entire investigated region and the average values of activity concentration with SD's were as follows: 2.92 ±â€¯0.47 Bq/kg for 230Th, 2.61 ±â€¯0.48 Bq/kg for 232Th, 4.32 ±â€¯0.80 Bq/kg for 234U and 3.97 ±â€¯0.71 Bq/kg for 238U. Examined Western Arctic tundra was not affected with any technically enhanced natural radioactivity.


Assuntos
Poluentes Radioativos do Ar/análise , Briófitas/química , Líquens/química , Cinza Radioativa/análise , Poluentes Radioativos do Solo/análise , Poluentes Radioativos da Água/análise , Alaska , Regiões Árticas , Canadá , Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Plutônio/análise , Monitoramento de Radiação/métodos , Tório/análise , Urânio/análise
6.
J Environ Manage ; 254: 109785, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31733484

RESUMO

It is important to understand the migration of Cesium (Cs) in soils, particularly after the nuclear power plant accident at Fukushima Dai-ichi, Japan. Dissolved organic matter (DOM) is one of factors affecting the migration of Cs in soils under flowing water conditions. We investigated the effect of DOM on the migration of Cs adsorbed to the clay planar site via laboratory column experiments. The sequence of DOM application had a significant influence on Cs transport in the soil. When DOM was applied concurrently with or prior to Cs application, the DOM adsorbed on to the clay planar site adsorbed onto the soil solid surface and enhanced Cs adsorption; consequently, it slowed Cs migration in the soil. In particular, in the case of DOM loaded prior to the application of Cs solution, a noticeable delay in Cs migration was observed. On the other hand, when DOM was applied to the soil where the Cs solution had been previously applied, the DOM desorbed Cs from the soil. DOM in liquid phase enhanced the migration of Cs through the formation of binding to organic matter. Majority of Cs affected by DOM was the exchangeable fraction that adsorbed to the clay planar site. In other words, DOM attached to the soil would adsorb Cs as a easily exchangeable form and depress migration of Cs. On the other hand, DOM in the soil solution may up take adsorbed Cs from the soil and enhanced the transport in the form of Cs bound to DOM.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo , Césio , Radioisótopos de Césio , Japão , Dióxido de Silício , Solo
7.
Medicine (Baltimore) ; 98(47): e17989, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31764810

RESUMO

RATIONALE: Managing the health of vulnerable groups is an important component of health care. Given the long-term burden of radiation-release incidents among those exposed, managing the health of vulnerable groups following a nuclear disaster is very important. However, there is limited information available concerning the long-term management of the health effects of radiation exposure in vulnerable groups following nuclear disasters. After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, Minamisoma City launched internal radiation exposure monitoring program for local residents, using whole body counter (WBC) units. In 2017, a man of low socio-economic status (SES), was found to have the highest level of internal contamination detected in a person living in the Soma District in recent years. This report describes the case so that the lessons learned can be applied in future nuclear disaster settings. PATIENT CONCERNS: A 77-year-old Japanese man, who had been homeless for 2 months and had been staying in the exclusion zone of Minamisoma City, was brought to our hospital. He had become homeless because a lack of communication between social support services had led to his eviction from leased housing after free housing support for evacuees was terminated. DIAGNOSES: He was admitted with a diagnosis of dehydration and malnutrition. A WBC unit was used to assess his body burden of radioactive cesium. This revealed levels of Cs-134 and Cs-137 of 538 Bq/body and 4,993 Bq/body, respectively. INTERVENTION: He received intravenous fluid therapy and health monitoring. The paperwork required for him to receive public income support was processed during hospitalization. OUTCOME: He was discharged to public housing after 9 days, and municipal workers started visiting him regularly after his discharge. LESSONS: A high level of internal radiation contamination may occur after a nuclear disaster. This may be associated with a decline in social support, poverty, and social isolation, and may have more impact on people in poor health than on the general population. It would be useful to strengthen linkages between local government and welfare service providers to increase social support for vulnerable groups requiring health care, not only following disasters, but also under normal circumstances.


Assuntos
Acidente Nuclear de Fukushima , Exposição à Radiação , Classe Social , Idoso , Humanos , Masculino , Fatores de Tempo , Contagem Corporal Total
8.
Int Heart J ; 60(6): 1253-1258, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31666454

RESUMO

On March 11, 2011, a great earthquake, known as the Great East Japan Earthquake, hit northeastern Japan, resulting in a tsunami that caused a nuclear disaster, the Fukushima Daiichi Nuclear Power Plant accident, forcing about 160,000 people to evacuate. We, therefore, sought to examine the effects of this evacuation on the onset of cardiovascular diseases and sudden death (SD) in Fukushima Prefecture, three years after the earthquake. We divided the evacuation zone into two areas, whole evacuation zone (Area 1) and partial evacuation zone (Area 2), and we defined the north district of the prefecture as the control area (Area 3). We cross-referenced the death certificate data with data from the Fukushima Prefecture acute myocardial infarction registration survey. For each area, we tallied the number of people who fell into the SD, myocardial infarction (MI), and MI suspected groups. We calculated the age-adjusted incidence rates and analyzed the differences in the adjusted incidence rates across three years using a Poisson regression model. The age-adjusted death rate of the SD group was significantly higher in 2011 in all areas than in 2012 or 2013 (P < 0.05). The total death rate was higher in Area 1 in March 2011, just after the disaster, than in the other two areas. The rate of SD was also higher in Area 1 than in the other areas in March 2011. The incidence of sudden cardiac death might have increased just after the Great East Japan Earthquake in the evacuation area, but not in other areas in Fukushima Prefecture.


Assuntos
Morte Súbita/epidemiologia , Terremotos , Acidente Nuclear de Fukushima , Cardiopatias/epidemiologia , Tsunamis , Adulto , Idoso , Feminino , Humanos , Incidência , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Distribuição de Poisson
9.
J Emerg Manag ; 17(4): 257-269, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31603518

RESUMO

The Fukushima disaster following the March 11, 2011 earthquake and tsunami in Japan demonstrates the complexity of responding to nuclear emergencies during a natural disaster. Current international safety standards and guidance do not specifically address this type of situation. The potential conflicts between the response to the conventional impacts and the radiological consequences, real and perceived, can impede the effectiveness of the overall emergency response. The present article discusses the strategic and operational challenges likely to be encountered in such a complex emergency, and draws conclusions on how countries should better plan for the low probability but high consequence impacts of natural disasters coincident with a nuclear accident at a nuclear power plant.


Assuntos
Desastres Naturais , Liberação Nociva de Radioativos , Emergências , Acidente Nuclear de Fukushima , Humanos , Japão , Centrais Nucleares , Tsunamis
10.
Mar Pollut Bull ; 145: 649-655, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590834

RESUMO

With the use of an in situ and static method for gamma-ray measurements, levels of radioactive cesium 137 on shallow rugged reefs which lie between 37.3° N and 37.4° N, from the coastline of Fukushima to 141.06° E, at a depth of around 10 m were surveyed for the first time from May 2016 to December 2017. To confirm the contact between the detector and a surface of rock, we used a fact that potassium containing minerals are abundant and uniformly distributed in the area, and thus the strength of the photoelectric peak of natural radioactive potassium 40 is nearly constant over the area. We have found that the levels of radioactive cesium 137 varied from point to point within a range from 1 × 104 Bq/m2 to 6 × 104 Bq/m2.


Assuntos
Radioisótopos de Césio/análise , Poluentes Radioativos da Água/análise , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Acidente Nuclear de Fukushima , Japão , Radioisótopos de Potássio/análise , Monitoramento de Radiação/instrumentação , Monitoramento de Radiação/métodos
12.
Rev Sci Tech ; 38(1): 103-111, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31564737

RESUMO

Supplying safe livestock products made from healthy animals is the primary purpose of the agriculture industry, making it essential to include agriculture in the One Health approach to disaster preparedness and response. After the Great East Japan Earthquake of 11 March 2011, and the following crisis at the Fukushima Nuclear Complex, producing and supplying safe livestock products became a challenging issue, because the area was highly polluted with radiation leaks from the nuclear plants. To produce livestock products that satisfied the safety standards for radioactive materials in food for humans, it was necessary to create feeding management guidelines and set standard limits for radioactive materials in animal feeds. The Ministry of Agriculture, Forestry and Fisheries (MAFF) established provisional maximum limits on radioactive caesium in feeds in order to secure safe food for the nation. Furthermore, there were other issues that Japan's livestock industry had to tackle. The authors outline key measures taken by the Livestock Industry Department of the MAFF to reconstruct the livestock industry, which was a small but important part of the whole reconstruction plan. They also discuss the measures implemented to protect companion animals.


Assuntos
Terremotos , Gado , Saúde Única , Agricultura , Animais , Acidente Nuclear de Fukushima , Humanos , Japão
13.
Medicine (Baltimore) ; 98(37): e17165, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31517868

RESUMO

A thyroid cancer ultrasonography screening for all residents 18 years old or younger living in the Fukushima prefecture started in October 2011 to investigate the possible effect of the radiological contamination after the Fukushima Daiichi Nuclear Power Plant accidents as of March 12 to 15, 2011. Thyroid cancer in 184 cases was reported by February 2017. The question arises to which extent those cancer cases are a biological consequence of the radiation exposure or an artefactual result of the intense screening of a large population.Experiences with the Chernobyl accident suggest that the external dose may be considered a valid surrogate for the internal dose of the thyroid gland. We, therefore, calculated the average external effective dose-rate (µSv/h) for the 59 municipalities of the Fukushima prefecture based on published data of air and soil radiation. We further determined the municipality-specific absolute numbers of thyroid cancers found by each of the two screening rounds in the corresponding municipality-specific exposed person-time observed. A possible association between the radiation exposure and the thyroid cancer detection rate was analyzed with Poisson regression assuming Poisson distributed thyroid cancer cases in the exposed person-time observed per municipality.The target populations consisted of 367,674 and 381,286 children and adolescents for the 1st and the 2nd screening rounds, respectively. In the 1st screening, 300,476 persons participated and 270,489 in the 2nd round. From October 2011 to March 2016, a total of 184 cancer cases were found in 1,079,786 person-years counted from the onset of the exposure to the corresponding examination periods in the municipalities. A significant association between the external effective dose-rate and the thyroid cancer detection rate exists: detection rate ratio (DRR) per µSv/h 1.065 (1.013, 1.119). Restricting the analysis to the 53 municipalities that received less than 2 µSv/h, and which represent 176 of the total 184 cancer cases, the association appears to be considerably stronger: DRR per µSv/h 1.555 (1.096, 2.206).The average radiation dose-rates in the 59 municipalities of the Fukushima prefecture in June 2011 and the corresponding thyroid cancer detection rates in the period October 2011 to March 2016 show statistically significant relationships.


Assuntos
Acidente Nuclear de Fukushima , Neoplasias Induzidas por Radiação/epidemiologia , Doses de Radiação , Neoplasias da Glândula Tireoide/epidemiologia , Adolescente , Criança , Pré-Escolar , Relação Dose-Resposta à Radiação , Detecção Precoce de Câncer , Geografia Médica , Humanos , Incidência , Lactente , Recém-Nascido , Japão/epidemiologia , Modelos Estatísticos , Neoplasias Induzidas por Radiação/diagnóstico por imagem , Prevalência , Exposição à Radiação/efeitos adversos , Glândula Tireoide/diagnóstico por imagem , Glândula Tireoide/efeitos da radiação , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Ultrassonografia
14.
Environ Pollut ; 255(Pt 2): 113236, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546076

RESUMO

After the Fukushima Daiichi Nuclear Power Plant accident, there has been an increasing concern regarding the contamination of wild mushrooms with radiocesium (134Cs and 137Cs) in eastern Japan. In this study, we analyzed the radioactivity monitoring data of 3189 wild edible mushrooms of 107 species collected by the 265 local municipalities in eastern Japan to investigate the radiocesium levels in wild mushrooms. Results of the analysis showed that radiocesium concentrations in mushrooms were normalized with radioactivity deposition data from aircraft monitoring, and then we evaluated the effects of species, sampled location, sampling year and regional deviation between 134Cs and 137Cs activity of specimens using a hierarchical Bayesian approach considering spatial autocorrelation (an intrinsic CAR model). Normalized activity concentration by species ranged from 1.1×10-4 to 2.3×10-2 (m2 kg-1, fresh weight). As reported in previous studies, the mycorrhizal species tended to have higher radiocesium concentrations. Some saprophytic species (e.g. Pholiota lubrica) also had high concentrations. For the mushroom species that were also evaluated in the post-Chernobyl studies, we found that the same species had similar trends of absorption capacities. Our results indicate the extensive analysis of public monitoring data is helpful to understand the situation of mushroom contamination and evaluate the internal dose by ingestion of wild mushrooms according to species and areas.


Assuntos
Agaricales/química , Radioisótopos de Césio/análise , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Teorema de Bayes , Acidente Nuclear de Fukushima , Japão
15.
Chemosphere ; 236: 124778, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549670

RESUMO

The radiation dose effects due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident are of public concern. Although indoor dust is an important exposure route for some hazardous chemicals, the radiation exposure dose from the radioactive caesium (Cs) in it has not been well investigated. Hence, in this study, we measured the radioactive Cs in the indoor dust of private houses in order to estimate the resulting human exposure. We collected vacuum cleaner dust twice (in April and June 2012, n = 250 and 241, respectively) in the prefectures of Chiba and Ibaraki, from houses located 150-200 km south from the FDNPP. The activity concentrations of 134Cs and 137Cs in the indoor dust were measured using germanium γ-ray detectors, and the exposure dose was calculated and the household-to-household variations were analysed. The median activity concentrations of 134Cs + 137Cs in the indoor dust collected in April and June were 1470 and 1340 Bq kg-1, respectively. The median committed effective doses via indoor dust ingestion were estimated as 0.73, 0.66, and 0.43 × 10-3 mSv year-1, and those via inhalation were estimated as 0.03, 0.04, and 0.06 × 10-3 mSv year-1 for one- and ten-year-old children and adults, respectively. Those were much smaller than the annual dose limit of 1 mSv year-1, which was set as a goal to be achieved in the a few years or decades (clear period has not been set). Within the detached houses, multiple regression analysis showed that wet wiping of floor was a significant reduction factor of the Cs concentration in dust; however, the small determination coefficient implies the presence of factors that were not considered in this study.


Assuntos
Poluentes Radioativos do Ar/análise , Poeira/análise , Acidente Nuclear de Fukushima , Monitoramento de Radiação/métodos , Adulto , Poluição do Ar em Ambientes Fechados/análise , Radioisótopos de Césio/análise , Criança , Humanos , Lactente , Japão , Centrais Nucleares , Doses de Radiação , Exposição à Radiação/análise , Radioatividade
16.
J Environ Radioact ; 208-209: 106040, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31518883

RESUMO

Because of the Fukushima Dai-ichi Nuclear Power Plant accident, forest ecosystems in wide areas were contaminated with 137Cs. It is important to characterize the behavior of 137Cs after its deposition onto forest surface environments for evaluating and preventing long-term radiation risks. In the present study, 137Cs vertical distributions in the soil profile were observed repeatedly at five forest sites with different vegetation types for 4.4 years after the accident in 2011, and 137Cs migration in the organic layer and mineral soil was analyzed based on a comparison of models and observations. Cesium-137 migration from the organic layer to the underlying mineral soil was represented by a two-component exponential model. Cesium-137 migration from the organic layer was faster than that observed in European forests, suggesting that the mobility and bioavailability of 137Cs could be suppressed rapidly in Japanese forests. At all sites, 137Cs transfer in mineral soil could be reproduced by a simple diffusion equation model with continuous 137Cs supply from the organic layer. The diffusion coefficients of 137Cs in the mineral soil were estimated to be 0.042-0.55 cm2 y-1, which were roughly comparable with those of European forest soils affected by the Chernobyl Nuclear Power Plant accident. Model predictions using the determined model parameters indicated that 10 years after the accident, more than 70% of the deposited 137Cs will migrate to the mineral soil but only less than 10% of the total 137Cs inventory will penetrate deeper than 10 cm in the mineral soil across all sites. The results of the present study suggest that the 137Cs deposited onto Japanese forest ecosystems will be retained in the surface layers of mineral soil for a long time.


Assuntos
Radioisótopos de Césio/análise , Florestas , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Japão , Modelos Químicos , Solo
17.
J Environ Radioact ; 208-209: 106041, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31494389

RESUMO

We developed a simple model to evaluate and predict the 137Cs discharge from catchments using a tank model and the L-Q equation. Using this model, the 137Cs discharge and discharge ratio from the Abukuma River and 13 other rivers in the Fukushima coastal region were estimated from immediately after the Fukushima accident up to 2017. The 137Cs discharge (and discharge ratio to the deposition inventory in the catchment) of the Abukuma River and 13 other rivers in the Fukushima coastal region during the initial six months after the accident were estimated to be 18 TBq (3.1%) and 11 TBq (0.79%), respectively. These values of 137Cs discharge ratio were 1-2 orders of magnitude higher than those observed after June 2011 in previous studies (Ueda et al., 2013; Tsuji et al., 2016; Iwagami et al., 2017a), indicating that the initial 137Cs discharge from the catchments through the rivers was significant. The simulated initial 137Cs discharge rates for the initial six months after the Fukushima accident were about 9-30 times larger in each catchment than those after that point until 2017, though initial 137Cs concentration in river water was derived from an extrapolation of data based on a two exponentially decreasing fitting. However, it was found that the impact on the ocean from the initial 137Cs discharge through the rivers can be limited because the 137Cs discharge from the Abukuma River and the 13 other rivers in the Fukushima coastal region (29 TBq) was two orders of magnitude smaller than the direct release from Fukushima Dai-ichi Nuclear Power Plant (FDNPP) into the ocean (3.5 PBq) and from atmospheric deposition into the ocean (7.6 PBq) (Kobayashi et al., 2013). This model is expected to be useful to evaluate and predict 137Cs discharge from catchments in future water management and in the estimation of 137Cs discharge into reservoirs and the ocean.


Assuntos
Radioisótopos de Césio/análise , Monitoramento de Radiação , Poluentes Radioativos da Água/análise , Poluição Radioativa da Água/estatística & dados numéricos , Acidente Nuclear de Fukushima , Japão , Rios
18.
Sci Total Environ ; 697: 134060, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31487588

RESUMO

The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan in 2011 released a large amount of radionuclides, primarily radiocesium-137 (137Cs; half-life: 30 years), resulting in long-term contamination of soil and consequently crops. Tillage is a common agricultural management practice that alters the vertical distribution of nutrients in the soil. However, the effect of tillage on 137Cs contamination in soil and crops over time remains unclear. In this study, we investigated the temporal changes in the vertical distribution of 137Cs in the soil, concentration of 137Cs in soybean and cover crops, and the transfer factor (TF) of 137Cs from the soil to crops under three tillage systems (rotary cultivation [RC], moldboard plow [MP], and no tillage [NT]; main factors) using three cover crops (hairy vetch, winter rye, and fallow weeds; side factors). The amount of 137Cs in the soil decreased exponentially with soil depth under the NT and RC treatments. By contrast, 137Cs showed uniform distribution at each soil depth tested under the MP treatment since 2012. The exchangeable 137Cs demonstrated a similar tendency as 137Cs. The 137Cs concentration in soybean (including grain and residue) and cover crops decreased exponentially with time. Consistently higher 137Cs concentration was observed in soybean grains under the NT treatment, suggesting that tillage continuously reduced the concentration of 137Cs in soybean over 7 years since the FDNPP accident. The TF of 137Cs from soil to soybean and cover crops decreased continuously over time; however, 137Cs concentration of soybean grain showed a positive linear correlation with its annual variation rate. Additionally, TF showed a positive logarithmic correlation with 137Cs relaxation depth in the soil. These results enhance our understanding of the long-term behavior and radioecology of 137Cs in agroecosystems in Japan since the radionuclide accident.


Assuntos
Agricultura , Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Produtos Agrícolas , Japão
19.
Environ Sci Technol ; 53(21): 12339-12347, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31490064

RESUMO

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the most significant quantity of radiocesium into the environment since Chernobyl, and detailed measurements over the initial 5 years provide new insights into fluvial redistribution of radiocesium. We found that the high initial activity concentration of 137Cs-bearing suspended sediment in rivers was followed by a steep exponential decline (λ1) which extended to approximately 1 year after the accident, while the rate of initial decline in radiocesium activity concentration in water was an order of magnitude higher than rates measured after Chernobyl. Fluvial transport of 137Cs to the ocean from the Abukuma river totaled 12 TBq between June 2011 and August 2015 and almost all this radiocesium (96.5%) was transported in the particulate form. The primary sources of 137Cs were paddy fields, farmland, and urban areas [plaque-forming unit (PFU)], discharging 85% of the exported 137Cs from 38% of the watershed area. After 1 year, activity concentrations were lower and exhibited a more gradual secondary decline (λ2) which was associated with reduced radiocesium losses from PFU areas, while forest areas continue to represent more stable contaminant stores.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo , Poluentes Radioativos da Água , Radioisótopos de Césio , Japão , Rios
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