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1.
Sci Total Environ ; 720: 137292, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32325549

RESUMO

The phytoremediation abilities of Hornwort (Ceratophyllum demersum L.) were tested under greenhouse and field conditions. Plants were exposed for 8, 16, and 24 days (greenhouse with stable isotope 133Cs), 8 days (field with 133Cs), and 8 days (climabox with radioactive isotope 134Cs). The plants were exposed to different concentration of stable Cs provided as CsCl (0.008, 0.033, 0.133, 0.267, 0.533, 0.800, 1.067, and 1.333 mM) and different activities of 134Cs (4.46, 4.46, 4.74, 4.64, 2.23 and 2.26 kBq). The results of the experiment revealed a significant effect (p < 0.001) of exposure time on Cs uptake. The results showed highest average 133Cs removal rates of 11%, 17% and 19% for 8, 16, and 24 days, respectively, in the greenhouse, 10% for the 134Cs experiment, and 27% for the field experiment with 133Cs. The results indicated that increasing the length of exposure lowered the uptake ability, hence indicating that the plant has limited capacity for Cs removal. The accumulated amount of Cs by plants is significantly dependent (p < 0.001) on the concentration of treatment and complies to a sigmoid curve. Comparison of experiments revealed the greenhouse experiment with 133Cs and the experiment with 134Cs did not differ significantly in their removal rate. However, the field experiment was significantly different from the previous two (p < 0.001), providing a higher removal rate. C. demersum was also able to resist phytotoxic effects of Cs in the greenhouse experiment for 16 days without significant effects (p > 0.05) on health. Even after 24 days of exposure, the plant resisted up to 0.267 mM treatment concentration with no significant tissue lesion (p > 0.05). These results indicate that C. demersum has potential for remediating aquatic habitats, especially in the case of acute events, where a short duration of phytoremediation may take place.


Assuntos
Poluentes Radioativos da Água/química , Biodegradação Ambiental , Transporte Biológico , Isótopos de Césio
2.
Health Phys ; 115(5): 550-560, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29878916

RESUMO

Hydroponic uptake studies were conducted to evaluate the uptake and translocation of Tc, Cs (stable analog for Cs), Np, and U into established and seedling Andropogon virginicus specimens under controlled laboratory conditions. Plant specimens were grown in analyte-spiked Hoagland nutrient solution for 24 h, 3 d, and 5 d. Translocation to shoots was greatest for Tc and Cs, likely due to their analogous nature to plant nutrients, while U (and Np to a lesser extent) predominantly partitioned to root tissue with less extensive translocation to the shoots. Plant age contributed significantly to differences in concentration ratios for all nuclides in shoot tissues (p ≤ 0.024), with higher concentration ratios for seedling specimens. Additionally, duration of exposure was associated with significant differences in concentration ratios of Cs and Tc for seedlings (p = 0.007 and p = 0.030, respectively) while plant part (root or shoot) was associated with significant differences in concentration ratios of established plants (p < 0.001 for both nuclides). Statistically significant increases in radionuclide uptake in seedling specimens relative to established plants under controlled conditions suggests that, in addition to geochemical factors, plant life stage of wild grasses may also be an important factor influencing radionuclide transport in the natural environment.


Assuntos
Andropogon/metabolismo , Isótopos de Césio/farmacocinética , Tecnécio/farmacocinética , Urânio/farmacocinética , Andropogon/crescimento & desenvolvimento , Hidroponia , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , Plântula/crescimento & desenvolvimento , Plântula/metabolismo
3.
J Environ Radioact ; 190-191: 51-65, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29753145

RESUMO

A methodology is presented to calibrate contributed Safecast dose rate measurements acquired between 2011 and 2016 in the Fukushima prefecture of Japan. The Safecast data are calibrated using observations acquired by the U.S. Department of Energy at the time of the 2011 Fukushima Daiichi power plant nuclear accident. The methodology performs a series of interpolations between the U.S. government and contributed datasets at specific temporal windows and at corresponding spatial locations. The coefficients found for all the different temporal windows are aggregated and interpolated using quadratic regressions to generate a time dependent calibration function. Normal background radiation, decay rates, and missing values are taken into account during the analysis. Results show that the standard Safecast static transformation function overestimates the official measurements because it fails to capture the presence of two different Cesium isotopes and their changing magnitudes with time. A model is created to predict the ratio of the isotopes from the time of the accident through 2020. The proposed time dependent calibration takes into account this Cesium isotopes ratio, and it is shown to reduce the error between U.S. government and contributed data. The proposed calibration is needed through 2020, after which date the errors introduced by ignoring the presence of different isotopes will become negligible.


Assuntos
Radiação de Fundo , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Calibragem , Isótopos de Césio/análise , Radioisótopos de Césio , Japão
4.
J Environ Radioact ; 186: 34-44, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29029765

RESUMO

Dynamics of the Fukushima-derived radiocesium and distribution of the natural stable isotope 133Cs in Japanese cedar (Cryptomeria japonica D. Don) forest ecosystems were studied during 2014-2016. For the experimental site in Yamakiya, Fukushima Prefecture, we present the redistribution of radiocesium among ecosystem compartments during the entire observation period, while the results obtained at another two experimental site were used to demonstrate similarity of the main trends in the Japanese forest ecosystems. Our observations at the Yamakiya site revealed significant redistribution of radiocesium between the ecosystem compartments during 2014-2016. During this same period radionuclide inventories in the aboveground tree biomass were relatively stable, however, radiocesium in forest litter decreased from 20 ± 11% of the total deposition in 2014 to 4.6 ± 2.7% in 2016. Radiocesium in the soil profile accumulated in the 5-cm topsoil layers. In 2016, more than 80% of the total radionuclide deposition in the ecosystem resided in the 5-cm topsoil layer. The radiocesium distribution between the aboveground biomass compartments at Yamakiya during 2014-2016 was gradually approaching a quasi-equilibrium distribution with stable cesium. Strong correlations of radioactive and stable cesium isotope concentrations in all compartments of the ecosystem have not been reached yet. However, in some compartments the correlation is already strong. An increase of radiocesium concentrations in young foliage in 2016, compared to 2015, and an increase in 2015-2016 of the 137Cs/133Cs concentration ratio in the biomass compartments with strong correlations indicate an increase in root uptake of radiocesium from the soil profile. Mass balance of the radionuclide inventories, and accounting for radiocesium fluxes in litterfall, throughfall and stemflow, enabled a rough estimate of the annual radiocesium root uptake flux as 2 ± 1% of the total inventory in the ecosystem.


Assuntos
Isótopos de Césio/análise , Radioisótopos de Césio/análise , Florestas , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Cryptomeria , Japão , Radioatividade
5.
Sci Total Environ ; 584-585: 88-95, 2017 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-28135617

RESUMO

To reveal the in planta behaviour of caesium (Cs), the stable isotope 133Cs was administered into 3-year-old Cryptomeria japonica seedlings by the application of 133CsCl aqueous solution to the bark surface. The administered 133Cs was quantified by ICP-MS measurements, which showed transportation of 133Cs in an ascending direction in the stem. Distribution of 133Cs was visualized using freeze-fixed C. japonica woody stem samples and cryo-time-of-flight secondary ion mass spectrometry/scanning electron microscopy (cryo-TOF-SIMS/SEM) analysis. Cryo-TOF-SIMS/SEM visualization suggested that 133Cs was rapidly transported radially by ray parenchyma cells followed by axial transportation by pith and axial parenchyma cells. Adsorption experiments using powdered C. japonica wood samples and X-ray absorption fine structure (XAFS) analysis suggested that 133Cs was in the hydrated state following its deposition into tracheid cell walls.


Assuntos
Isótopos de Césio/metabolismo , Cryptomeria/metabolismo , Caules de Planta/metabolismo , Madeira/metabolismo , Plântula , Espectrometria de Massa de Íon Secundário
6.
Sci Rep ; 7: 39874, 2017 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-28051136

RESUMO

After the Fukushima Daiichi Nuclear Power Plant accident in March 2011, concentrations of cesium isotopes (133Cs, 134Cs, and 137Cs) were measured in zooplankton collected in the Pacific off the east coast of Japan from May 2012 to February 2015. The time series of the data exhibited sporadic 137Cs concentration peaks in zooplankton. In addition, the atom ratio of 137Cs/133Cs in zooplankton was consistently high compared to that in ambient seawater throughout the sampling period. These phenomena cannot be explained fully by the bioaccumulation of 137Cs in zooplankton via ambient seawater intake, the inclusion of resuspended sediment in the plankton sample, or the taxonomic composition of the plankton. Autoradiography revealed highly radioactive particles within zooplankton samples, which could be the main factor underlying the sporadic appearance of high 137Cs concentrations in zooplankton as well as the higher ratio of 137Cs/133Cs in zooplankton than in seawater.


Assuntos
Poluentes Radioativos da Água/análise , Zooplâncton/química , Animais , Isótopos de Césio/química , Radioisótopos de Césio/química , Acidente Nuclear de Fukushima , Sedimentos Geológicos/química , Japão , Oceano Pacífico , Água do Mar/análise , Zooplâncton/metabolismo
7.
J Environ Radioact ; 164: 104-112, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27447690

RESUMO

In order to understand the influence of the Fukushima Daiichi nuclear power plant accident on the ecosystem in hilly and mountainous areas of Fukushima Prefecture, chronological changes in the levels of radiocesium in arthropod species were investigated. From 2012 to 2014, arthropods from different trophic levels were sampled and the air radiation dose rates at the sampling sites were analyzed. The air radiation dose rates showed a significant and constant reduction over the 2 years at the sampling sites in Fukushima. The median radiocesium concentration (134Cs + 137Cs) detected in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, dropped continuously to 0.080 and 0.078 Bq/g fresh weight, respectively, in 2014. In contrast, no significant reduction in radioactive contamination was observed in the Jorô spider, Nephila clavata, in which the level remained at 0.204 Bq/g in 2014. A significant positive correlation between radiocesium concentration and the air radiation dose rate was observed in the rice grasshopper, the Emma field cricket and the Jorô spider. The highest correlation coefficient (ρ = 0.946) was measured in the grasshopper.


Assuntos
Artrópodes/química , Isótopos de Césio/análise , Acidente Nuclear de Fukushima , Monitoramento de Radiação , Animais , Gafanhotos/química , Gryllidae/química , Centrais Nucleares , Aranhas/química
8.
J Environ Radioact ; 157: 102-12, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27032341

RESUMO

Cesium-137 derived from the Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contaminated large areas of agricultural land in Eastern Japan. Previous studies before the accident have indicated that flooding enhances radiocesium uptake in rice fields. We investigated the influence of water management in combination with fertilizers on (137)Cs concentrations in rice plants at two fields in southern Ibaraki Prefecture. Stable Cs ((133)Cs) in the plants was also determined as an analogue for predicting (137)Cs behavior after long-term aging of soil (137)Cs. The experimental periods comprised 3 y starting from 2012 in one field, and 2 y from 2013 in another field. These fields were divided into three water management sections: a long-flooding section without midsummer drainage, and medial-flooding, and short-flooding sections with one- or two-week midsummer drainage and earlier end of flooding than the long-flooding section. Six or four types of fertilizer subsections (most differing only in potassium application) were nested in each water management section. Generally, the long-flooding treatment led to higher (137)Cs and (133)Cs concentrations in both straw and brown rice than medial- and short-flooding treatments, although there were some notable exceptions in the first experimental year at each site. Effects of differing potassium fertilizer treatments were cumulative; the effects on (137)Cs and (133)Cs concentrations in rice plants were not obvious in 2012 and 2013, but in 2014, these concentrations were highest where potassium fertilizer had been absent and lowest where basal dressings of K had been tripled. The relationship between (137)Cs and (133)Cs in rice plants was not correlative in the first experimental year at each site, but correlation became evident in the subsequent year(s). This study demonstrates a novel finding that omitting midsummer drainage and/or delaying drainage during the grain-filling period enhances uptake of both (137)Cs and (133)Cs.


Assuntos
Irrigação Agrícola , Isótopos de Césio/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Fertilizantes , Oryza/efeitos dos fármacos , Potássio/farmacologia
9.
J Magn Reson ; 261: 110-20, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26561738

RESUMO

(133)Cs nuclear magnetic resonance (NMR) spectroscopy was conducted on (133)Cs(+) in gelatin hydrogels that were either relaxed or stretched. Stretching generated a septet from this spin-7/2 nucleus, and its nuclear magnetic relaxation was studied via z-spectra, and two-dimensional nuclear Overhauser (NOESY) spectroscopy. Various spectral features were well simulated by using Mathematica and the software package SpinDynamica. Spectra of CsCl in suspensions of human erythrocytes embedded in gelatin gel showed separation of the resonances from the cation inside and outside the cells. Upon stretching the sample, the extracellular (133)Cs(+) signal split into a septet, while the intracellular peak was unchanged, revealing different alignment/ordering properties of the environment inside and around the cells. Differential interference contrast light microscopy confirmed that the cells were stretched when the overall sample was elongated. Analysis of the various spectral features of (133)Cs(+) reported here opens up applications of this K(+) congener for studies of cation-handling by metabolically-active cells and tissues in aligned states.


Assuntos
Isótopos de Césio , Eritrócitos/química , Hidrogéis/química , Ressonância Magnética Nuclear Biomolecular/métodos , Algoritmos , Césio/sangue , Cloretos/sangue , Simulação por Computador , Eritrócitos/ultraestrutura , Humanos , Íons , Microscopia de Interferência , Método de Monte Carlo , Software
10.
Radiat Prot Dosimetry ; 167(1-3): 219-22, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25956780

RESUMO

Due to releases of radionuclides in the Fukushima Daiichi Nuclear Power Plant accident, radiocesium ((134)Cs and (137)Cs) has been incorporated into large varieties of plant species and soil types. There is a possibility that radiocesium taken into plants is being diffused by pollen. Radiocesium concentrations in cedar pollen have been measured in Ome City, located in the Okutama area of metropolitan Tokyo, for the past 3 y. In this research, the variation of radiocesium concentrations was analysed by comparing data from 2011 to 2014. Air dose rates at 1 m above the ground surface in Ome City from 2011 to 2014 showed no significant difference. Concentration of (137)Cs contained in the cedar pollen in 2012 was about half that in 2011. Between 2012 and 2014, the concentration decreased by approximately one-fifth, which was similar to the result of a press release distributed by the Japanese Ministry of Agriculture, Forestry and Fisheries.


Assuntos
Cedrus/química , Isótopos de Césio/análise , Acidente Nuclear de Fukushima , Pólen/química , Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/análise , Poluentes Radioativos do Ar/análise , Bioensaio/métodos , Japão , Doses de Radiação , Cinza Radioativa/análise , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Análise Espaço-Temporal
11.
J Hazard Mater ; 279: 52-9, 2014 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-25038573

RESUMO

In this work, the capability of nanometallic Ca/CaO methanol suspension in removing and/or immobilizing stable ((133)Cs) and radioactive cesium species ((134)Cs and (137)Cs) in contaminated fly ash was investigated. After a first methanol and second water washing yielded only 45% of (133)Cs removal. While, after a first methanol washing, the second solvent with nanometallic Ca/CaO methanol suspension yielded simultaneous enhanced removal and immobilization about 99% of (133)Cs. SEM-EDS analysis revealed that the mass percent of detectable (133)Cs on the fly ash surface recorded a 100% decrease. When real radioactive cesium contaminated fly ash (containing an initial 14,040Bqkg(-1)(134)Cs and (137)Cs cumulated concentration) obtained from burning wastes from Fukushima were reduced to 3583Bqkg(-1) after treatment with nanometallic Ca/CaO methanol suspension. Elution test conducted on the treated fly ash gave 100BqL(-1) total (134)Cs and (137)Cs concentrations in eluted solution. Furthermore, both ash content and eluted solution concentrations of (134)Cs and (137)Cs were much lower than the Japanese Ministry of the Environment regulatory limit of 8000Bqkg(-1) and 150BqL(-1) respectively. The results of this study suggest that the nanometallic Ca/CaO methanol suspension is a highly potential amendment for the remediation of radioactive cesium-contaminated fly ash.


Assuntos
Compostos de Cálcio/química , Cálcio/química , Radioisótopos de Césio/química , Césio/química , Cinza de Carvão/análise , Metanol/química , Óxidos/química , Césio/isolamento & purificação , Isótopos de Césio/química , Isótopos de Césio/isolamento & purificação , Radioisótopos de Césio/isolamento & purificação , Incineração , Microscopia Eletrônica de Varredura , Eliminação de Resíduos , Suspensões
12.
J Plant Res ; 127(1): 57-66, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24338062

RESUMO

After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plants grown in the actual paddy field in Fukushima City. We herein conducted a two-year survey in 2011 and 2012 of radioactive and non-radioactive Cs accumulation in rice using a number of rice cultivars grown in the paddy field in Fukushima City. Our study demonstrated a substantial variation in Cs accumulation levels among the cultivars of rice.


Assuntos
Radioisótopos de Césio/metabolismo , Acidente Nuclear de Fukushima , Oryza/metabolismo , Solo/química , Agricultura , Biodegradação Ambiental , Isótopos de Césio/análise , Isótopos de Césio/metabolismo , Radioisótopos de Césio/análise , Japão , Centrais Nucleares , Oryza/química , Caules de Planta/química , Caules de Planta/metabolismo , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Poluentes Radioativos do Solo/metabolismo , Especificidade da Espécie
13.
J Plant Res ; 127(1): 67-71, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24338063

RESUMO

After the accident of the Fukushima 1 nuclear power plant in March 2011, radioactive cesium was released and paddy field in a wide area of Fukushima Prefecture was contaminated. To reduce radioactive Cs uptake by rice, it is important to understand factors that affect Cs uptake in rice. Here we describe our study in 2011 and 2012 to investigate Cs concentration in two rice cultivars, Koshihikari and Hitomebore, the top two cultivars in Fukushima prefecture, grown under different fertilizer conditions in the contaminated paddy field. Our study demonstrated that high nitrogen and low potassium conditions increase Cs concentrations both in straw and brown rice.


Assuntos
Radioisótopos de Césio/metabolismo , Acidente Nuclear de Fukushima , Oryza/metabolismo , Solo/química , Agricultura , Biodegradação Ambiental , Isótopos de Césio/análise , Isótopos de Césio/metabolismo , Radioisótopos de Césio/análise , Fertilizantes , Japão , Nitrogênio/farmacologia , Centrais Nucleares , Oryza/química , Oryza/efeitos dos fármacos , Caules de Planta/química , Caules de Planta/efeitos dos fármacos , Caules de Planta/metabolismo , Potássio/farmacologia , Monitoramento de Radiação , Sementes/química , Sementes/efeitos dos fármacos , Sementes/metabolismo , Poluentes Radioativos do Solo/análise , Poluentes Radioativos do Solo/metabolismo , Especificidade da Espécie
14.
J Environ Radioact ; 129: 48-56, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24368267

RESUMO

The trace level of metals and particularly radioactive ones should be monitored to evaluate the transfer along the trophic chain, assess the risk for biota and can be used for global changes assessment. Plants respond rapidly to all changes in the ecosystem conditions and are widely used as indicators and predictors for changes in hydrology and geology. In this work we represent our successful development and applications of a methodology for monitoring of stable and radioactive strontium and cesium in marine biota (Black Sea algae's). In case of radioactive release they are of high interest. We use ED-XRF, gamma spectrometers and LSC instrumentation and only 0.25 g sample. Obtained results are compared with those of other authors in same regions. The novelty is the connection between the radioactive isotopes and their stable elements in algae in time and space scale. All our samples were collected from Bulgarian Black Sea coast.


Assuntos
Clorófitas/química , Feófitas/química , Rodófitas/química , Alga Marinha/química , Poluentes Químicos da Água/análise , Poluentes Radioativos da Água/análise , Mar Negro , Isótopos de Césio , Monitoramento de Radiação , Isótopos de Estrôncio , Poluentes da Água
15.
Rev Sci Instrum ; 84(9): 093507, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24089828

RESUMO

After the 2011 nuclear power plant accident at Fukushima, radiocesium contamination in food became a serious concern in Japan. However, low background and high efficiency radiocesium detectors are expensive and huge, including semiconductor germanium detectors. To solve this problem, we developed a radiocesium detector by employing positron emission tomography (PET) technology. Because (134)Cs emits two gamma photons (795 and 605 keV) within 5 ps, they can selectively be measured with coincidence. Such major environmental gamma photons as (40)K (1.46 MeV) are single photon emitters and a coincidence measurement reduces the detection limit of radiocesium detectors. We arranged eight sets of Bi4Ge3O12 (BGO) scintillation detectors in double rings (four for each ring) and measured the coincidence between these detectors using PET data acquisition system. A 50 × 50 × 30 mm BGO was optically coupled to a 2 in. square photomultiplier tube (PMT). By measuring the coincidence, we eliminated most single gamma photons from the energy distribution and only detected those from (134)Cs at an average efficiency of 12%. The minimum detectable concentration of the system for the 100 s acquisition time is less than half of the food monitor requirements in Japan (25 Bq/kg). These results show that the developed radiocesium detector based on PET technology is promising to detect low level radiocesium.


Assuntos
Análise de Alimentos , Contaminação Radioativa de Alimentos/análise , Acidente Nuclear de Fukushima , Raios gama , Tomografia por Emissão de Pósitrons , Isótopos de Césio/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Tomografia por Emissão de Pósitrons/instrumentação , Tomografia por Emissão de Pósitrons/métodos
16.
Environ Int ; 61: 73-6, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24103348

RESUMO

Namie Town was heavily contaminated by the Fukushima Daiichi Nuclear Power Station accident. The thyroid equivalent dose for residents who lived in Namie was estimated using results of whole body counting examinations which were carried out by the Japan Atomic Energy Agency a few months after the nuclear accident. Photon peaks of (131)I and (134)Cs were previously measured by the authors using a NaI(Tl) scintillation spectrometer and that information was used to estimate the (131)I/(134)Cs activity ratio of total intake in the present study. The maximum values of (131)I/(134)Cs activity ratio corresponding to thyroid uptake factors of 0.3, 0.1 and 0.03 were evaluated to be 0.9, 2.6 and 8.7, respectively. The maximum value of the (131)I/(134)Cs activity ratio was used to obtain the most conservative thyroid equivalent dose estimation. The maximum internal exposure of the thyroid to (131)I on the basis of (134)Cs accumulated in the body measured by the whole body counter was estimated to be 18mSv. This value was much smaller than 50mSv that the International Atomic Energy Agency recommends as the dose at which exposed persons should take stable iodine tablets.


Assuntos
Poluentes Radioativos do Ar/análise , Isótopos de Césio/análise , Exposição Ambiental , Acidente Nuclear de Fukushima , Radioisótopos do Iodo/análise , Glândula Tireoide/química , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Japão , Masculino , Pessoa de Meia-Idade , Contagem Corporal Total , Adulto Jovem
17.
J Environ Radioact ; 121: 2-11, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22717303

RESUMO

Steady state approaches, such as transfer coefficients or bioaccumulation factors, are commonly used to model the bioaccumulation of (137)Cs in aquatic foodwebs from routine operations and releases from nuclear generating stations and other nuclear facilities. Routine releases from nuclear generating stations and facilities, however, often consist of pulses as liquid waste is stored, analyzed to ensure regulatory compliance and then released. The effect of repeated pulse releases on the steady state assumption inherent in the bioaccumulation factor approach has not been evaluated. In this study, I examine the steady state assumption for aquatic biota by analyzing data for two cesium isotopes in the same biota, one isotope in steady state (stable (133)Cs) from geologic sources and the other released in pulses ((137)Cs) from reactor operations. I also compare (137)Cs bioaccumulation factors for similar upstream populations from the same system exposed solely to weapon test (137)Cs, and assumed to be in steady state. The steady state assumption appears to be valid for small organisms at lower trophic levels (zooplankton, rainbow smelt and 0+ yellow perch) but not for older and larger fish at higher trophic levels (walleye). Attempts to account for previous exposure and retention through a biokinetics approach had a similar effect on steady state, upstream and non-steady state, downstream populations of walleye, but were ineffective in explaining the more or less constant deviation between fish with steady state exposures and non-steady state exposures of about 2-fold for all age classes of walleye. These results suggest that for large, piscivorous fish, repeated exposure to short duration, pulse releases leads to much higher (137)Cs BAFs than expected from (133)Cs BAFs for the same fish or (137)Cs BAFs for similar populations in the same system not impacted by reactor releases. These results suggest that the steady state approach should be used with caution in any situation where reactor releases are episodic or pulse in nature, even if the magnitude of these releases is small.


Assuntos
Isótopos de Césio/farmacocinética , Radioisótopos de Césio/farmacocinética , Peixes , Cadeia Alimentar , Poluentes Radioativos da Água/farmacocinética , Animais , Tamanho Corporal , Canadá , Monitoramento Ambiental , Comportamento Alimentar , Peixes/crescimento & desenvolvimento , Peixes/metabolismo , Reatores Nucleares , Rios/química , Zooplâncton
18.
Sci Rep ; 2: 1005, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23256039

RESUMO

The fate of (137)Cs derived from the Fukushima nuclear accident fallout and associated radiological hazards are largely dependent on its mobility in the surface soils of forest ecosystems. Thus, we quantified microbial and adsorptive retentions of (137)Cs in forest surface (0-3 cm) soils. The K(2)SO(4) extraction process liberated 2.1%-12.8% of the total (137)Cs from the soils. Two soils with a higher content of clay- and silt-sized particles, organic carbon content, and cation exchange capacity showed higher (137)Cs extractability. Microbial biomass was observed in all of the soils. However, the (137)Cs extractability did not increase after destruction of the microbial biomass by chloroform fumigation, providing no evidence for microbial retention of the Fukushima-fallout (137)Cs. The results indicate that uptake of (137)Cs by soil microorganisms is less important for retention of potentially mobile (137)Cs in the forest surface soils compared to ion-exchange adsorption on non-specific sites provided by abiotic components.


Assuntos
Biomassa , Césio/análise , Acidente Nuclear de Fukushima , Microbiologia do Solo , Solo/análise , Árvores/química , Isótopos de Césio/análise , Japão , Poluentes Radioativos do Solo , Árvores/crescimento & desenvolvimento , Árvores/microbiologia
19.
Mar Environ Res ; 81: 83-9, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22975383

RESUMO

Diatom fossils from core sediments and living diatoms from water samples of Notoro Lagoon in northern Japan were examined to evaluate natural climate effects on lagoon environmental changes. In 1974, the artificial inlet was excavated. Immediately after, the anoxic bottom water in Notoro Lagoon began to disappear due to an increasing water exchange rate. However, chemical oxygen demand (COD) in the bottom water of Notoro Lagoon gradually increased, with fluctuations, during the last 30 years. In addition, the dominant diatom assemblages in Notoro Lagoon shifted to ice-related and spring bloom taxa after the excavation. The dominant taxa of each year in the sediment core were also strongly related to the timing of lagoon ice melting. This is because the COD in Notoro Lagoon was affected by the deposited volume of blooming diatoms, which was controlled by the duration of ice cover and the timing of ice discharge to the Okhotsk Sea likely due to an air pressure pattern change over the northern North Pacific like the Pacific Decadal Oscillation (PDO).


Assuntos
Mudança Climática , Ecossistema , Sedimentos Geológicos/análise , Camada de Gelo , Plâncton/fisiologia , Animais , Aquicultura , Análise da Demanda Biológica de Oxigênio , Isótopos de Césio/análise , Diatomáceas/fisiologia , Monitoramento Ambiental , Sedimentos Geológicos/química , Japão , Chumbo/análise , Oceanos e Mares , Pectinidae/fisiologia , Densidade Demográfica , Fatores de Tempo
20.
J Biosci Bioeng ; 114(6): 600-5, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22857899

RESUMO

Possible contamination by radioactive cesium (Cs), released by the Fukushima Daiichi Nuclear Plant Accident in Japan on March 2011, has been a matter of concern with respect to Japanese sake made from rice grains cultivated in affected fields. In this study, the behavior of stable (133)Cs, which is a useful analogue for predicting the behavior of radioactive Cs, was investigated in the production of sake using rice grains harvested in Japan in 2010. The concentration of stable (133)Cs in the polished rice grains decreased gradually with decreasing milling ratios until a ratio of 70% was reached, and below that point, it did not change significantly. The (133)Cs concentration in the 70% polished rice was approximately 20% of that found in brown rice. The sake was brewed on a small scale using 70% polished rice, and the transfer of (133)Cs from rice to sake was examined. Approximately 30-40% of (133)Cs in the 70% polished rice was removed during the washing and the steeping of the rice grains, and approximately 40% of the (133)Cs in the 70% polished rice was transferred to the sake. If the radioactive Cs species behaves similarly, these results suggest that brown rice containing 100 Bq/kg radioactivity of Cs would generate 70% polished rice grains containing 20 Bq/kg and that the sake brewed from these grains would contain 3-5 Bq/kg.


Assuntos
Isótopos de Césio/análise , Radioisótopos de Césio/análise , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Manipulação de Alimentos , Oryza/metabolismo , Vinho/análise , Isótopos de Césio/metabolismo , Produtos Agrícolas/química , Produtos Agrícolas/metabolismo , Manipulação de Alimentos/métodos , Indústria de Processamento de Alimentos/métodos , Acidente Nuclear de Fukushima , Japão , Oryza/química
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