We analyzed publicly available data of Fukushima 137Cs concentrations in coastal fish, in surface and bottom waters, and in surface marine sediments and found that within the first year of the ...accident pelagic fish lost 137Cs at much faster rates (mean of ∼1.3% d–1) than benthic fish (mean of ∼0.1% d–1), with benthopelagic fish having intermediate loss rates (mean of ∼0.2% d–1). The loss rates of 137Cs in benthic fish in the first year were more comparable to the decline of 137Cs concentrations in sediments (0.03% d–1), and the declines in pelagic fish were more comparable to the declines in seawater. Retention patterns of 137Cs in pelagic fish were comparable to that in laboratory studies of fish in which there were no sustained 137Cs sources, whereas the benthopelagic and benthic fish species retained 137Cs to a greater extent, consistent with the idea that there is a sustained additional 137Cs source for these fish. These field data, based on 13 511 data points in which 137Cs was above the detection limit, are consistent with conclusions from laboratory experiments that demonstrate that benthic fish can acquire 137Cs from sediments, primarily through benthic invertebrates that contribute to the diet of these fish.
The ecological environment of the Tibetan Plateau, known as the “Third Pole of the Earth”, is extremely sensitive and fragile. With rapid societal development, environmental problems on the Tibetan ...Plateau have become prominent, as it is downwind of the emission sources from densely populated areas in the Middle East and South Asia, and the plateau has become one of the regions significantly affected by transboundary pollutant transmission (including black carbon, BC). The Tibetan Plateau has a long history of life and religious sacrifices, including aromatic plant-burning, which were recorded in the geologic record; therefore, BC can be used as a potential indicator to study the changes in religious activities. In this study, BC analysis was carried out based on the plausible dating framework tested by the AMS
14
C and
137
Cs methods on successive sediment cores from Lake Dalzong, an alpine lake in the Gannan Tibetan Autonomous Prefecture, northeast of the Tibetan Plateau. It was found that the BC in the lake sediments mainly accumulated through proximity wet deposition, and its content changes reflected the prevalence of surrounding religious activities. The study results indicate that the area of Lake Dalzong has experienced three periods of enhanced religious activities in the last millennium: 1490–1565 CE (mid-Ming Dynasty), 1810–1890 CE (late Qing Dynasty), and 1920 CE to the present (since the founding of the Republic of China), and the increase in religious activities on this centennial time scale is a response to concurrent social development. This study is the first to extract information on the variation in religious activities from lake sediments on the Tibetan Plateau, which will help advance the study of the historical context of the Anthropocene on the Tibetan Plateau.
Soil erosion is especially severe in areas affected by intermittent heavy rainfalls after dry periods, and human practices such as deforestation. Mediterranean mountain environments underwent ...conversion of rangelands into croplands during the previous centuries to increase agricultural production but this process was reversed after land abandonment in the middle of the twentieth century allowing the natural revegetation. To understand the effect of the past practices and the current agricultural management, we have combined the strength of empirical data and spatially distributed modelling in a medium‐sized catchment representative of agroforestry landscapes of NE Spain. We developed an ensemble technique composed of 137Cs‐derived soil redistribution rates as specific point values and as grid‐based setup calibration for the WaTEM/SEDEM. Thus, we overcame the point specific limitation of the 137Cs measurement and the need for calibration of spatially distributed models that allow a spatial interpretation of soil redistribution in the catchment. We implemented an automated routine model tool to increase the calculation speed and calibrate the model thus, allowing estimates of the main model parameters for simulating a variety of temporal scenarios. With this method a good fit between modelled and measured soil redistribution rates (R2 = 0.82) was obtained (Nash–Sutcliffe efficiency: 0.79). Estimates were also consistent with the previous apportions of sediment provenance obtained by the fingerprinting technique. An increase of 300% in sediment export was predicted for the past scenario when most of the catchment was cultivated, while a reduction of 40% occurred in the future scenario of land abandonment. A high influence of input resolution was found, wherein model efficiency was reduced when pixel‐size was increased. Our study demonstrates that spatially distributed models combined with 137Cs‐derived rates provide a powerful tool to understand the driving factors of erosion and delineate the hotspot areas that could suffer high erosion if submitted to certain management practices.
Flowchart of the implemented methodology.
Nuclear accidents and decommissioning in the nuclear industry would release a large number of radioactive aerosols which endangers the natural environment and the health of workers. Therefore, there ...is an urgent need for environment-friendly aerosol suppressants to control and handle environmental pollution problems caused by radioactive aerosols. In this paper, sodium alginate (SA), a type of polyphenol material (TP), and alkyl glycosides (APGs) were selected as the components of the compound aerosol suppressant and the optimal proportion was generated via the method of D-optimal mixture design. Furthermore, the cesium aerosol sedimentation effect of the optimized compound aerosol suppressants was evaluated via sedimentation efficiency, the change in particle concentration cumulative concentration fraction of the cesium aerosol sedimentation process. The results showed that the aerosol sedimentation efficiency was 99.82% which was much higher than nature settlement, 18.6% and water spraying sedimentation, 43.3%. Moreover, after spraying the compound suppressant, it displayed a good effect on settling the cesium aerosol particles with a diameter of less than 1 µm, as the concentration of particles was reduced from 55.49% to 44.53%. Finally, the sedimentation mechanism of the compound aerosol suppressant and cesium aerosol particles, such as the coagulation effect, was analyzed using the particle size distribution.
Abstract Pipe scaling is a common problem in geothermal power plants. Currently, the pipeline withinside the Karaha Telaga Bodas geothermal subject is indicated to incorporate scale because of ...pressure anomalies. On-stream pipe scale inspection techniques are needed to maintain the production process. This research aims to apply the gamma-ray transmission tomography technique to pipelines in geothermal fields. The gamma-ray tomography system consists of a 137 Cs (2.96 GBq) gamma radiation source, a scintillation detector, mechanical parts, control parts, and data acquisition. Scanning was performed at three predetermined points: brine pipe 1, two-phase pipe, and brine pipe 2. The system scans half of the pipe circumference (180°) and divides it into 32 projections (5.625°). Each projection performs a translational scan with a resolution of 4 mm. Three cross-sectional images of the pipe were obtained, showing the inside condition. Pipe scale was observed at three scanning points with a thickness of 12 mm-48 mm. Gamma tomography can potentially be a tool for examining pipe scale thickness in geothermal fields. The use of a single detector is a limitation that needs to be improved. Apart from that, the stability of the control and mechanical parts must also be improved.
The dynamic behavior of alkali metal ions, Li
+
, Na
+
, K
+
, Rb
+
and Cs
+
in aqueous solutions is one of the most important topics in solution chemistry. Since these alkali metals contain nuclear ...magnetic resonance (NMR) active nuclei, it is possible to directly measure the diffusion constants of the alkali metal ions using the pulsed field gradient (PFG) NMR method. In this paper, the
7
Li,
23
Na,
87
Rb,
133
Cs and
1
H resonances are observed for diffusion constants in aqueous solution and the solvent H
2
O. Until now, the values of the diffusion constant have been lacking when discussing hydration effects around alkali metal ions. It is known that the static ionic radius (
R
ion
) increases with increasing the atomic number, and the experimental diffusion constants also increase with increasing the atomic number, which is opposite to the Stokes-Einstein (SE) relation. It suggests that alkali metal ions diffuse through a space of 10
−6
m accompanying the hydrated spheres with a time interval of 10
−3
s. For each alkali metal ion, the dynamic ionic radius is evaluated.
Stokes radius (dynamic ionic radius) of the alkali metal ions
versus
the ionic radius (
R
ion
) at 303 K. The dotted line is a guide for the 1 : 1 relation.
The transfer factor (TF) of radioactive cesium-137 (
137
Cs) to shiitake (
Lentinula edodes
) cultivated on bed logs varies greatly. Therefore, the present study investigated which factors affect the ...TF using stable cesium-133 (
133
Cs) and sawdust medium with 5% rice bran as a model, which had similar
133
Cs TFs to bed-log cultivation. It was found that the Cs concentration and nutrient concentration (represented by the nitrogen concentration) concerned with the TF in the model sawdust medium. In addition, the TFs calculated using total
137
Cs and
133
Cs concentrations differed in both bed-log cultivation and the model sawdust medium cultivation, while the TFs calculated using exchangeable
137
Cs and
133
Cs concentrations were the same in sawdust medium cultivation, indicating that exchangeable Cs in the medium is the source of Cs for the fruiting body and the former difference was due to the presence of other chemical speciation of Cs that could not be absorbed. One purpose of the TF on the mushroom farm is to determine the fruiting body
137
Cs concentration at the start of bed-log cultivation, therefore the prediction method of TF are discussed considering the future changes of
137
Cs concentrations in trees.
Abstract
FLASH at DESY (Hamburg, Germany) and the European XFEL photoinjectors are operated by laser driven RF-guns. For both user-facilities cesium telluride (Cs
2
Te) photocathodes are successfully ...used since several years. We present recent data on the lifetime and quantum efficiency (QE) of the current photocathode at FLASH #105.2, operated before and after a long shutdown. In addition, data for the cathodes that recently have been exchanged at the European XFEL will be presented.
On 1 April 2017, six years have passed since the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, and the Japanese government declared that some residents who lived in Tomioka Town, ...Fukushima Prefecture could return to their homes. We evaluated environmental contamination and radiation exposure dose rates due to artificial radionuclides in the livelihood zone of residents (living space such as housing sites), including a restricted area located within a 10-km radius from the FDNPS, immediately after residents had returned home in Tomioka town. In areas where the evacuation orders had been lifted, the median air dose rates were 0.20 μSv/h indoors and 0.26 μSv/h outdoors, and the radiation exposure dose rate was 1.6 mSv/y. By contrast, in the "difficult-to-return zone," the median air dose rate was 2.3 μSv/h (20 mSv/y) outdoors. Moreover, the dose-forming artificial radionuclides (radiocesium) in the surface soil were 0.018 μSv/h (0.17 mSv/y) in the evacuation order-lifted areas and 0.73 μSv/h (6.4 mSv/y) in the difficult-to-return zone. These findings indicate that current concentrations of artificial radionuclides in soil samples have been decreasing in the evacuation order-lifted areas of Tomioka town; however, a significant external exposure risk still exists in the difficult-to-return zone. The case of Tomioka town is expected to be the first reconstruction model including the difficult-to-return zone.
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