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1.
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
2.
Sci Total Environ ; 750: 142346, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182182

RESUMO

The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures. We aimed to estimate the comprehensive dose due to internal and external exposures at the particularly high natural radiation area, and to discuss the enhancement mechanism of radon. A car-borne survey was conducted to estimate the external doses from terrestrial radiation. Indoor radon measurements were made in 47 dwellings over three to five months, covering the two typical seasons, to estimate the internal doses. Atmospheric radon gases were simultaneously collected at several heights to evaluate the vertical distribution. The absorbed dose rates in air in the study area vary widely between 50 nGy h-1 and 1109 nGy h-1. Indoor radon concentrations ranged from 124 Bq m-3 to 1015 Bq m-3. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m-3 recommended by the World Health Organization. Furthermore, the outdoor radon concentrations measured were comparable to the high indoor radon concentrations. The annual effective dose due to external and internal exposures in the study area was estimated to be 27 mSv using the median values. It was found that many residents are receiving radiation exposure from natural radionuclides over the dose limit for occupational exposure to radiation workers. This enhanced outdoor radon concentration might be as a result of the stable atmospheric conditions generated at an exceptionally low altitude. Our findings suggest that this area provides a unique opportunity to conduct an epidemiological study related to health effects due to chronic low dose-rate radiation exposure.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Radiação de Fundo , Humanos , Indonésia , Doses de Radiação , Radônio/análise
3.
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
4.
Environ Monit Assess ; 192(12): 775, 2020 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-33219883

RESUMO

The activity concentration of natural radionuclides in farm soil and most common indigenous food crops (maize, potato, cowpea) in oil-producing (Philippi, Uitenhage, and Hertenbos farms) and non-oil-producing (Ukulinga farm) areas of South Africa was measured using a Hyper Pure Germanium detector. Consequently, the transfer of these radionuclides from soil-to-crops was estimated. The mean activity concentration of 226Ra, 232Th, and 40K for farm soil samples are 30.71 ± 11.77, 31.97 ± 8.90, 345.97 ± 98.62 Bq.kg-1 for Philippi; 18.67 ± 6.70, 31.55 ± 11.48, 191.93 ± 33.39 Bq.kg-1 for Uitenhage; 38.03 ± 17.44, 41.18 ± 31.54, 381.89 ± 163.40 Bq.kg-1 for Hartenbos; and 8.47 ± 2.87, 8.65 ± 3.52, 94.22 ± 25.97 ± 25.97 Bq.kg-1 for Ukulinga. The mean activity concentration of 226Ra, 232Th, and 40K for crop samples are 4.54 ± 1.47, 4.87 ± 1.69, 140.18 ± 35.38 Bq.kg-1 for Philippi; 9.17 ± 4.79, 3.85 ± 1.87, 136.75 ± 22.04 Bq.kg-1 for Uitenhage; 7.97 ± 2.91, 4.62 ± 2.40, 105.97 ± 48.65 Bq.kg-1 for Hartenbos; and 4.23 ± 1.63, 2.72 ± 1.19, 48.36 ± 15.55 Bq.kg-1 for Ukulinga. The activity concentration and soil-to-crop transfer factors for 40K were found to be much higher, possibly because this element is critical in crop growth. The results showed that the crop samples' transfer factor is in the order cowpea>potato>maize. This study showed that activity concentrations of 226Ra, 232Th, and 40K in crops and the corresponding transfer factors depend on activity concentrations of the same radionuclides in soil.


Assuntos
Monitoramento de Radiação , Poluentes Radioativos do Solo , Monitoramento Ambiental , Fazendas , Radioisótopos/análise , Solo , Poluentes Radioativos do Solo/análise , África do Sul
5.
Environ Monit Assess ; 192(12): 764, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-33200258

RESUMO

Indoor radon (222Rn) measurements were carried out using solid state nuclear track detectors (SSNTD) in some dwellings from southwestern Nigeria. This was aimed at statistically assessing influence of building characteristics on the measured radon and estimating excess lifetime cancer risks (ELCR). The measured radon concentrations followed lognormal distribution and were significantly influenced by some building properties. The arithmetic mean (1.60 mSv) of annual effective doses (AEDs) due to indoor radon was observed to be higher than the world average level (1.15 mSv) but less than lower limit (3 mSv) of International Commission on Radiological Protection (ICRP). The evaluated excess lifetime cancer risk ranged from 1.5 to 28.1 (MPy)-1 with an average value of 6.3 (MPy)-1, indicating that after exposure to indoor radon for 70 years, 6 people in every 1000 are likely to suffer the risk of developing lung cancer. Adequate ventilation systems were recommended for houses with high level of radon to avoid unnecessary exposure to radon. However, the investigated data would form important component of the database required to set up guidelines and policy of controlling radon at home.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental , Habitação , Humanos , Nigéria , Radônio/análise
6.
Environ Sci Process Impacts ; 22(11): 2291-2297, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33112309

RESUMO

Due to the more volatile nature of 210Po in relation to 210Pb, an imbalance of activity concentrations in high temperature combustion processes can be observed, especially in fine particulates (diameter < 0.1, 0.2 and 0.5 µm). In the atmosphere and in the soil around coal-fired power plants, 210Pb and 210Po concentrations are a combination of activities from natural and anthropogenic sources. In this study only portions of 210Po and 210Pb radionuclides resulting from energy production activities were analyzed. Due to the high mobility of fine particles, a surface area of 172 km × 140 km in central Poland was chosen for simulation. For validation of the modeling approach, three grid versions were applied: 1 km, 2 km and 4 km. Simulated results confirmed experimental-computational values of an excess of both radionuclides in the atmosphere in 2017 in the city of Lodz. Different aerosol fractions, seasons and various grids in the selected area were subjected to 36 individual simulations. The 210Po activity concentrations measured in winter and summer 2017 were 42.5 and 8.99 µBq m-3, respectively. Simulated and measured values of artificial 210Po and 210Pb activities are well correlated.


Assuntos
Poluentes Radioativos do Ar , Monitoramento de Radiação , Poluentes Radioativos do Ar/análise , Cidades , Chumbo , Polônia , Polônio , Centrais Elétricas , Radioisótopos
7.
Artigo em Chinês | MEDLINE | ID: mdl-33036530

RESUMO

Objective: To understand the personal dose level of nuclear medical workers in a hospital, and to provide basis for health management of nuclear medicine occupational population. Methods: From January 2014 to December 2018, 147 radiation workers in a hospital were selected as the monitoring objects, and the individual dose monitoring data were analyzed. The correlation between individual dose and clinical workload was analyzed. Results: The average annual personal dose of 147 staff members was below the national dose limit. Compared with the radiation department, the average annual personal dose of nuclear medical staff was higher, and the difference was statistically significant (P<0.05) . There was a positive correlation between the annual average personal dose and the corresponding injection workload (Rs=0.69, P<0.05) . Conclusion: The occupational exposure risk of nuclear medical technicians and nurses is high, and reasonable protective measures should be taken to reduce the radiation exposure dose. Conclusion The occupational exposure risk of nuclear medical technicians and nurses is high, and reasonable protective measures should be taken to reduce the radiation exposure dose.


Assuntos
Medicina Nuclear , Exposição Ocupacional , Exposição à Radiação , Monitoramento de Radiação , Humanos , Exposição Ocupacional/análise , Doses de Radiação
8.
PLoS One ; 15(9): e0239296, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32931520

RESUMO

Following the Fukushima Daiichi Nuclear Power Plant accident in March 2011, radionuclides such as iodine-131, cesium-134 and cesium-137 were released into environment. In this study, we collected wild mushrooms from the Kawauchi Village of Fukushima Prefecture, located less than 30 km southwest of the Fukushima nuclear power plant, to evaluate their radiocesium (134Cs+137Cs) concentrations and the risk of internal radiation exposure in local residents. 342 mushroom samples were collected from 2016 to 2019. All samples were analysed for radiocesium content by a high-purity germanium detector. Among 342 mushroom samples, 260 mushroom samples (76%) were detected the radiocesium exceeding the regulatory limit of radiocesium (100 Bq/kg for general foods in Japan). The median of committed effective dose from ingestion of wild mushrooms was in the range of 0.015-0.053 mSv in 2016, 0.0025-0.0087 mSv in 2017, 0.029-0.110 mSv in 2018 and 0.011-0.036 mSv in 2019 based on the assumption that Japanese citizens consumed wild mushrooms for 1 year. Thus, our study showed that although radiocesium is still detected in mushrooms collected in Kawauchi village even after 5 to 9 years later, the committed effective dose due to consuming mushrooms was lower than 1 mSv per year. Long-term comprehensive follow-up should monitor radiocesium concentrations in wild mushrooms to support the recovery of the community after the nuclear disaster.


Assuntos
Agaricales/efeitos da radiação , Radioisótopos de Césio/isolamento & purificação , Agaricales/química , Radioisótopos de Césio/toxicidade , Contaminação Radioativa de Alimentos/estatística & dados numéricos , Acidente Nuclear de Fukushima , Humanos , Japão , Centrais Nucleares , Monitoramento de Radiação
9.
Environ Sci Pollut Res Int ; 27(34): 43389-43395, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32965644

RESUMO

Radon exhaled from building material surfaces is an important source of indoor radon. Yangjiang, located in the southern part of mainland China, is well-known as a high background radiation area (HBRA). Rather, high levels of radon and thoron concentration have been observed in adobe and brick houses. Reducing the indoor radon concentration remains an important issue in the high background radiation areas of China and the world. Generally, the walls of Chinese dwellings are solid. In this paper, a simple one-dimensional model for predicting the radon diffusion in a cavity wall is proposed, and an analysis formula describing the radon exhalation rate from cavity wall surfaces is presented. The influence on the radon exhalation rate due to leakage through structural joints and building material cracks is analyzed. The simulation results indicate that the radon exhalation rate from a cavity wall surface is far lower than that from a solid wall. The structure of cavity walls themselves is therefore useful as a mechanism for reducing the indoor radon in high background radiation areas across the world.


Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Radônio , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Radiação de Fundo , China , Materiais de Construção , Expiração , Habitação , Radônio/análise
10.
J Environ Radioact ; 223-224: 106396, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32868093

RESUMO

Two radionuclide transport models for the Red Sea are described: a Lagrangian model to deal with emergency situations and a Eulerian model better suited to longer term simulations, as for instance required in case of chronic radionuclide releases. Baroclinic circulation is obtained for both transport models from HYCOM ocean model. The Lagrangian model also includes tides, which are obtained from a standard tidal model customized to the Red Sea, and currents induced by local winds. Both models describe exchanges of radionuclides between water and sediments. A number of simulations were carried out to illustrate capabilities of the models. Additionally, flushing times over the Red Sea were evaluated with the Eulerian model, as another example of model use.


Assuntos
Monitoramento de Radiação , Oceano Índico , Radioisótopos/análise , Água do Mar , Poluentes Radioativos da Água/análise
11.
J Environ Radioact ; 223-224: 106387, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32868094

RESUMO

The contamination in the near exclusion zone of the Chernobyl nuclear power plant (ChNPP) with 90Sr, 238-240Pu and 241Am is associated with irradiated nuclear fuel particles. Fit for purpose models enabling long term prediction of mobility and bioavailability of particle-associated radionuclides are crucial for radiation protection of humans and the environment, as well as for planning of remediation measures and future land use. In the present work, a dynamic fuel particle dissolution model developed in 1999-2002 is described and validated using data based on sampling in 2015. The model is based on the characterization of the radionuclide source term of the waste in a shallow sub-surface radioactive waste storage, trench #22, in the Chernobyl Pilot Site (CPS) located in the Red Forest, 2.5 km west of the ChNPP, as well as the description of physical and chemical properties of the fuel particles and subsequent radionuclide leaching into the soil solution. Transformation rate constants of the fuel particle dissolution model related to topsoil, radioactive waste trench and submerged materials, and drained cooling pond sediments, should largely control the mobility and bioavailability of radionuclides (e.g., solubility in the soil, migration to groundwater and transfer to plants). The predicting power of the Chernobyl fuel particle dissolution model with respect to radionuclide leaching dynamics was validated using samples from the same experimental site, showing that predicted particle leaching and subsequent mobility and bioavailability were within 46 ± 3% of the observed data. Therefore, linking source- and release-scenario dependent characteristics of radioactive particles to their potential weathering can provide information that can be implemented in impact assessments models for existing contaminated areas as well as for future events.


Assuntos
Acidente Nuclear de Chernobyl , Monitoramento de Radiação , Florestas , Humanos , Poluentes Radioativos do Solo/análise , Solubilidade , Ucrânia
12.
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
13.
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
14.
J Environ Radioact ; 223-224: 106390, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32883535

RESUMO

The presence of artificial and natural radioactivity in the environment is currently a topic of great relevance and ecological interest, even in human health issue, due to the increase of different anthropogenic activities. The use of multicommuted flow analysis techniques (e.g. Multi-Syringe Flow Injection Analysis - MSFIA, Lab-On-Valve - LOV and Lab-In-Syringe - LIS) has allowed the automation of radiochemical procedures to separate and preconcentrate radionuclides in environmental and biological samples. In comparison with the manual approach commonly used in routine analysis for radioactivity monitoring, the automation has enabled the development of highly reproducible methodologies with a great analysis frequency. Moreover, during the analytical procedure, the intervention of the analyst is drastically reduced, minimizing the radiological risk. The automation also offers significant advantages such as minimum consumption of time and reagents, reducing the cost and the generation of waste, contributing to the green chemistry. In this review, several multicommuted flow analysis techniques (MSFIA, LOV and LIS) reported in the last decade applied for the development of automatic sample treatment methodologies, used to separate, preconcentrate and quantify 90Sr, 99Tc, natural U and 226Ra in biological and environmental samples are described and critically compared.


Assuntos
Monitoramento de Radiação , Análise de Injeção de Fluxo , Humanos , Radioisótopos
15.
J Environ Radioact ; 223-224: 106370, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32883536

RESUMO

Tritium is a radioisotope of hydrogen with a half-life of 12.32 years and was used for its luminescent properties by the watchmaking industry from 1962 to the 2008. Tritiated luminescent salts were integrated in the paints applied on the index and dial of watches and clocks. French and Swiss watchmaking workshops used more than 28 000 TBq of tritium over this period of time and produced almost 350 million watches. Despite the end of tritiated salts use in watchmaking workshops in 1992 in France and 2008 in Switzerland, high level of organically bound tritium (OBT) are still observed in sediments of the Rhône River downstream the Lake Geneva. Contamination of the Rhône River by tritiated hot particles since 1962 up to nowadays remains poorly documented. In order to assess the long term behavior and fate of technogenic tritium in this river and its trajectories in the river system, two sediment cores were collected at the upstream (UC) and downstream (DC) part of the Rhône River in France and OBT contents were determined. For both sedimentary cores, maximum OBT contents were registered over the 1980s when tritium was intensively used by watchmaking industries. These residual OBT contents are 1 000 to 10 000 fold higher than current natural background levels in riverine sediments. The OBT contents progressively decreased since 1989 with close effective half-life in upstream and downstream area (5 ± 2 years). The OBT contents were lower in DC than in UC due to the dilution by uncontaminated sediments delivered by tributaries not affected by the watchmaking industries. Trajectories analysis indicates that the resiliency of the Rhône River system in regards to this contamination would be reached in 14-70 years and in 14-28 years respectively for the upstream and downstream part of the river.


Assuntos
Monitoramento de Radiação , França , Rios , Suíça , Trítio/análise , Poluentes Radioativos da Água/análise
16.
J Environ Radioact ; 223-224: 106379, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32905852

RESUMO

Adequate radiological protection requires the quantification of radionuclide transfer to the human food chain, which is essential for the estimation of ingestion doses. Transfer parameters are key inputs for the development of radioecological models and decision support systems. There are many literature compilations of these parameters, however, most of values were calculated in temperate climates, and data for Mediterranean ecosystems are scarce. In this study, transfer factors to foodstuffs collected in Mediterranean ecosystems, in Spain, were compared to reported values for temperate climate. Foodstuff included cereals, meat (beef, lamb and pork), dairy products (milk, cheese yogurt, and kefir), and also typical products of Mediterranean diet, such as olives, olive oil, grapes and wine. Radioactive (137Cs, 226,228Ra and 40 K) and stable elements (Cs, Sr, K, Na, Ca, Mg, P, Pb, U and Th) were measured to enable the calculation of transfer factors. As a consequence, data for transfer factors in Mediterranean systems were increased by about 120 and 200 values for plant and animal products, respectively. Due to the low level radiocaesium concentration in Spanish ecosystems, transfer factors for this radioisotope were largely 'less than' values. Therefore, stable Cs and Sr transfer factors were used as proxy for comparison with temperate values.


Assuntos
Ecossistema , Animais , Monitoramento de Radiação , Radioatividade , Poluentes Radioativos do Solo/análise , Espanha
17.
J Environ Radioact ; 223-224: 106378, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32911270

RESUMO

The solid-liquid distribution coefficient (Kd) is a key input parameter in radioecological risk models. However, its large variability hampers its usefulness in modelling transport processes as well as its accuracy in representing soil-radionuclide interactions. To assist in the selection of Kd values and their cumulative distribution functions for study areas without site specific information, a critically reviewed dataset was developed, containing more than 5000 soil Kd entries for 83 elements and an additional 2000 entries of Kd data for 75 elements gathered from a selection of other geological materials. For the specific case of americium (Am), the dataset contained 109 entries for soils and 33 additional entries for sediment and subsoils. The analysis of the Am Kd soil dataset showed that values varied 4-orders of magnitude, and consequently the resulting Am Kd best estimate (geometric mean (GM): 4.6 × 103 L kg-1) lacked sufficient reliability. The objective of this study was to calculate cumulative distribution functions and statistically evaluate this dataset to determine if the Am Kd variability in soils could be reduced by considering various factors, including: 1) measurement methods, 2) key soil properties, 3) the use of chemical analogue data, and 4) the use of analogue data. Accounting for Am Kd experimental method (i.e., sorption vs. desorption; long-vs. short-term experiments) had little effect on reducing variability. However, accounting for key soil factors (i.e., organic matter content (OM), pH, soil texture) succeeded in reducing variability of Am Kd, especially when combining pH and OM. While previous data sets have used 20% OM content as a critical value to distinguish between mineral and organic soils, this study shows that this critical value should be reduced to 10% OM to minimize Am Kd variability. The inclusion in the dataset of Am Kd from other geological materials (e.g., gyttjas, tills, and subsoils) and Kd values from trivalent lanthanides (Ln (III)) and actinides (An (III)) (172 additional entries) did not statistically affect the Am Kd geometric means of the various pH and OM partial datasets. The larger composite dataset (> 310 entries), with both chemical analogues and geological material analogues to address data gaps, increased the statistical power for calculating Kd best estimates with lower variability, thereby enhancing their usefulness for radionuclide risk calculations.


Assuntos
Monitoramento de Radiação , Solo , Adsorção , Amerício/análise , Reprodutibilidade dos Testes , Poluentes do Solo/análise
18.
J Environ Radioact ; 223-224: 106386, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32911271

RESUMO

A detailed study of 137Cs redistribution was conducted within a small agricultural catchment in the highly contaminated Plavsk radioactive hotspot in the Tula region of Central Russia, 32 years after the Chernobyl nuclear power plant (NPP) accident, which occurred on April 26, 1986. Although more than three decades have passed since the Chernobyl NPP incident, 137Cs contamination is high. The 137Cs inventory varies from 67 to 306 kBq·m-2, which is 2-6 times higher than the radiation safety standard; however, the soils remain suitable for crop cultivation. The initial 137Cs fallout within the Plavsk radioactive hotspot was extremely heterogeneous, with a trend of decreasing 137Cs inventories from the NW to the SE directions within the studied territory. Contemporary 137Cs inventories are also very heterogeneous in the studied catchment. However, the trend of the initial 137Cs fallout does not appear in the contemporary 137Cs inventories on the slopes. Two methods of interpolation (expert-visual and automatic) were used to calculate the 137Cs budget, revealing high similarity in their 137Cs loss estimates; however, a large discrepancy was observed in their 137Cs gain estimates. A detailed analysis of 137Cs redistribution revealed the importance of hollows and "plow ramparts" (positive topographic forms on the boundaries of cultivated fields) in the transport and deposition of sediments. A quarter of the total 137Cs gain was deposited within the arable land, whereas a quarter was deposited within the non-plowing sides of the dry valley; the other half was deposited in the valley bottom. About 7-8 × 106 kBq of the 137Cs inventory flowed out of the catchment area, which was only about 2% of the 137Cs fallout after the Chernobyl NPP accident. About 89% of the total 137Cs reserve is concentrated in the top (0-25 cm) layer of soils, regardless of land use or location within the catchment.


Assuntos
Acidente Nuclear de Chernobyl , Monitoramento de Radiação , Radioisótopos de Césio , Cinza Radioativa/análise , Federação Russa , Solo , Poluentes Radioativos do Solo/análise
19.
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
20.
J Environ Radioact ; 223-224: 106397, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32911273

RESUMO

The information on the absorbed dose rate which is derived from natural radionuclides is needed to evaluate additional exposure dose. However, there is inadequate positional resolution and precision for such data around Fukushima Dai-ichi Nuclear Power Station (FDNPS). In this study, we created a map of the absorbed dose rate that is derived from natural radionuclides based on several airborne radiation monitoring data. The reliability and accuracy of the created map was verified by comparison with the many in-situ measurements on the ground. To evaluate the effectiveness of this study, the effective half-lives of the ambient dose rate at residential areas of Fukushima Prefecture were assessed by discriminating these absorbed dose rate of the natural background from the results of a periodic dose rate survey by local government. The results of the distribution of natural background absorbed dose rates are expected to contribute to the evaluation of the additional exposure dose after the FDNPS accident.


Assuntos
Acidente Nuclear de Fukushima , Monitoramento de Radiação , Radioisótopos de Césio/análise , Raios gama , Japão , Reprodutibilidade dos Testes
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