The concentration of Cs in the environment is in the order of parts per billion (ppb) or parts per trillion (ppt). As a result, the peaks at 100 ppm can be assigned to CsC in the silicate sheets. This result supports our assignment because CsC on the clay surface and in the silicate plate is easily ion-exchanged by KC [6].
Speciation of 137 Cs and 129 I in Soil After the Fukushima NPP Accident
- Introduction
- Material and Methods .1 Soil Samples
- Column-Infiltration Experiments Using the Rainwater from the Tokyo Metropolitan Hot-Spot Area
- Leaching of Radionuclides from Soils Using the Batch Method
- Separation of 137 Cs and 129 I in Soil Samples
- Purification of Iodine Isotopes for Accelerator Mass Spectrometry (AMS) Measurement
- Measurement of Radioactivity in Environmental Samples by Gamma-Ray Spectrometry
- Results and Discussion
- Conclusion
We investigated the infiltration of 137Cs from rainwater into the soil environment through column experiments on April 1, 2011. The groundwater sample was discharged from the Kanto-play in the Tokyo metropolitan area and taken in March 2010 before the Fukushima plant accident. . We extracted 137Cs and 129I from three surface soil samples from the Kanto-playa layer in ETMA and Nagadoro in Fukushima.
Table 2.4 shows the concentrations of 137Cs and 134Cs in surface soil collected at ETMA in October 2011, 7 months after the accident. Both 137Cs and 134Cs were not detected in shallow groundwater and suspended solids collected from the filter (Table 2.7).
137Cs was mainly detected in forest litter [5] but 137Cs was detected up to a depth of 10 cm in soil without litter [15]. Because rain power is buffered in litter when the surface of the soil contains litter, it is difficult for rain to penetrate directly into the deep part of the soil. 40 cm, even if I had penetrated 10 cm deep into the ground without litter and/or grass immediately after the accident.
Traces of 131I in the groundwater did not reach the 50-cm depth by the end of June 2011, which corresponds to the length of time of 10 times of. Acknowledgment This study is partially supported by JST Initiatives for Basic and Generic Strategic Research for Atomic Energy. Open Access This chapter is distributed under the terms of the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Initiatives for Basic and Generic Strategic Research for Atomic Energy by the Ministry of Education, Culture, Sports, Science and Technology of Japan.
- Introduction
- Materials and Methods
- Results and Discussion
- Conclusion
In this study, the isotopic measurement of various samples collected from May to September 2011 was performed by”-spectrometry and TIMS. A soil sample was collected in the village of Hinoemata, which is one of the sampling plots of the Fukushima local government. In particular, the signal intensity from the soil sample was too low to estimate both isotopic ratios.
Other elements clearly interfered with the mass spectrometry measurements of the seaweed sample, and so neither isotope ratio was evaluated. The mass spectrometry of the seawater sample shows that the 134Cs signal overlaps with the tail of the 133Cs signal (see Figure 3.1); nevertheless, the isotope ratio of 135Cs/137Cs can be obtained. 134Cs/137Cs in the samples (evaluated by both spectrometry and TIMS) is consistent with the results of the other study; however, the proportion of land from Hinauwata is slightly lower.
Therefore, the value of the isotope ratio in environmental samples collected in the future may indicate the origin of radioactive cesium from TIMS. To obtain the initial cesium isotopic ratios at the time of the Fukushima accident, environmental samples were collected in Fukushima Prefecture during 2011. These results were in good agreement with each other (i.e., the results were independent of the method of definition used) as well as with other studies.
Based on the initial isotopic ratio derived from the Fukushima accident, the isotopic ratio of cesium in environmental samples collected in the future can be expected to estimate the contribution of the accident through comparisons with the effects of global fallout.
Application of Mass Spectrometry for Analysis of Cesium and Strontium in Environmental
Analysis of Cesium Isotope Compositions in
Environmental Samples by Thermal Ionization Mass Spectrometry-2
- Introduction
- Experimental
- Irradiation of UO 2 for Study of Radioactive Cs and Sr
- Recovery of Cs and Sr
- Analysis of Isotopic Composition of Cesium and Strontium
- Analysis of Environmental Samples
- Results and Discussion
- Isotopic Analysis of Radioactive Cs and Sr from Irradiated UO 2
- Analysis of Isotopic Compositions of Cs and Sr from Environmental Samples
- Conclusions
Due to the difference in the generation process and the half-life of radioactive Cs, the isotopic ratios are 134Cs/137Cs and. From the analysis data of the isotopic compositions, the information about the origin of radioactive nuclide release would be obtained. For the investigation of the recovery/analysis method for cesium and strontium, the radioactive Cs and Sr were first generated by irradiation of natural uranium at KUR.
The effluent was heated to dryness and the residue dissolved in 20L of 1 M HNO3 for Cs isotopic composition analysis. Mass spectra of radioactive Cs and Sr were obtained with a secondary electron multiplier (SEM) detector due to the low total amounts of radionuclide loaded into the filament. This suggests that stable Sr isotopes can also be used for Sr FP analysis.
The •87/86–values of samples ITT01 to ITT07 in Table 4.1 agreed within error demonstrating the reproducibility of the isotope ratio measurement including chemical treatment. The results of the isotope ratio measurements for all samples are summarized in Table 4.1 and shown in Figure 4.5a. The isotope ratio of 87Sr/86Sr has received attention as an indicator of plant production area and reported that the 87/86 values ranged from 25.0 to 5.5 [18].
The isotope ratios of 135Cs/137Cs show the significant difference from the reported values of global precipitation (ca. 0.5 for the Chernobyl accident and ca. for the natural sample, as the Sr concentration varies from ppb level to several hundreds of ppm level (Fig. 4.6). , the detectable lower limit of the isotope ratio of For the study of the recovery/analysis method of Cs and Sr, Cs and Sr were recovered from the natural uranium irradiated at KUR.
Migration of Radioactive Cesium to Water from Grass and Fallen Leaves
Introduction
As a result of these factors, the radiation level in the surrounding areas has been increased due to the presence of radioactive material on the ground. In addition, after deposition on the soil surface, trees and grasses absorbed the radiocesium into the soil through their roots. Due to their long half-lives, Cs-134 (2 years) and Cs-137 (30 years) are responsible for the continued presence of radioactive material outside the 1F site, even four years after the event.
We are particularly interested in determining the amount of radiocesium that migrates to the water from grasses, fallen leaves and soil. Due to the greater amount of rainfall in Fukushima, it is possible that radiocesium is transferred through water. In addition, it should be taken into account that the chemical form of radiocesium deposited in Fukushima is different from that deposited in Chernobyl.
It is therefore necessary to use samples collected in Fukushima to study the environmental behavior of radiocesium in this area. To assess the effect on water resources, it is therefore considered important to evaluate the amount of radiocesium migrating into the water from grass and fallen leaves. We report herein a process for determining the Cs content in grass and fallen leaves and in water after leaching.
We expect that it will be possible to use the obtained results for the prediction of radiocesium behavior in the environment.
Materials and Methods .1 Sample Collection
- Sample Preparation
- Radiocesium Migration to Water
- Radiocesium Deposition in Soil
Because radiocesium concentrations in the sample were low, it was desirable to remove as much water as possible from the sample to accurately measure radioactivity. The dried substance was scraped from the surface of the dish by washing with water (10 mL) and transferred to a U-8 container. The radiocesium content of the samples was measured using the HPGe detector to determine the radioactivity of the radiocesium that migrated from the plant samples into the water.
Using the sample collected in May 2014, a similar experiment was conducted comparing the migration rate with water using both deionized water and rainwater. However, water is often in contact with soil, and since the clay minerals found in the soil strongly adsorb radiocesium, it is expected that radiocesium in water can be deposited in soil. We therefore decided to investigate this by exposing soil to a solution containing radiocesium for 3 days, and the variations in the radiocesium concentration in the solutions were measured.
The solution needed for this experiment was prepared using fallen leaves collected at Yamakiya Elementary School. The concentration of radiocesium was then increased by reducing the water content using an evaporation dish and a heating mantle. After this time, the aqueous solution was filtered to remove all soil particles and collected.
Results and Discussion
The migration rate is defined as the ratio between the radioactivity that migrated into the water and the radioactivity of the sample before immersion. 5.1, in the case of grass, almost all of the transposable radiocaesium had passed into the water after 60 days. Furthermore, it was seen that little migration was observed after 120 days, so that the total migration rate for 120 days was comparable to that for 400 days.
5.2, the migration rate of fallen leaves was small, although an increase in migration rate was observed even after 400 days. First, it must be taken into account that the radiocaesium found in the grass has been absorbed through the roots from the soil. In contrast, radiocesium released after the accident was deposited on the surface of fallen leaves and was not absorbed through the roots.
Using a sample collected in May 2014, we compared the migration rate for deionized water with that obtained for rainwater. Migration rates from clover or pine needles were greater than from wormwood, while migration rates from fallen broadleaf were greater than from fallen needle leaves. Finally, Figure 5.6 shows the results of the residual solution (ie, the ratio of the post-soak concentration to the pre-soak concentration).
This is probably due to the large amounts of soil present in the area, so the radiocaesium could not be transported over a large area.
