Time trends in radiocaesium in the Japanese diet following nuclear weapons testing and Chernobyl:implications for long term contamination post-Fukushima

Estimation of time changes in radiocaesium in foodstuffs is key to predicting the long term impact of the Fukushima accident on the Japanese diet. We have modelled >4000 measurements, spanning 50 years, of 137Cs in foodstuffs and whole diet in Japan after nuclear weapons testing (NWT) and the Chernobyl accident. Broadly consistent long term trends in 137Cs activity concentrations are seen between different agricultural foodstuffs; whole diet follows this general trend with remarkably little variation between averages for different regions of Japan. Model blind tests against post-NWT data for the Fukushima Prefecture showed good predictions for radiocaesium in whole diet, spinach and Japanese radish (for which good long term test data were available). For the post-Fukushima period to 2015, radiocaesium in the average diet followed a declining time trend consistent with that seen after NWT and Chernobyl. Data for different regions post-Fukushima show a high degree of mixing of dietary foodstuffs between regions: predictions which assumed that only regionally produced food was consumed significantly over-estimated empirical data. Predictions of average committed effective internal doses from dietary 137Cs (2011 to 2061) in nonevacuated parts of the Fukushima Prefecture show that average internal dose is relatively low. This study focuses on average regional ingestion dose rates and does not attempt to make site specific predictions. However, the temporal trends identified could form a basis for site specific predictions of long term activity concentrations in agricultural products and diet both outside and (to assess potential re-use) inside currently evacuated areas

The Holistic Aspect of the Phenomenon of Entanglement

It is my aim to compare the conceptual and historical paths that led Bohr and Schrödinger to develop their positions with regard to the phenomenon of entanglement. For this purpose, the concept of holism and non-separability in relation to the views of Bohr and Schrödinger will be crucial for reconstructing their standpoints. The idea will be upheld that the concept of non-separability underlies the phenomenon of entanglement. Furthermore, I shall place emphasis on the divergences between Bohr and Schrödinger in spite of their shared holistic world view

Removal of Radiocesium from Food by Processing: Data Collected after the Fukushima Daiichi Nuclear Power Plant Accident -13167

ABSTRACT Removal of radiocesium from food by processing is of great concern following the accident of TEPCO's Fukushima Daiichi Nuclear Power Plant accident. Foods in markets are monitored and recent monitoring results have shown that almost all food materials were under the standard limit concentration levels for radiocesium (Cs-134+137), that is, 100 Bq kg -1 in raw foods, 50 Bq kg -1 in baby foods, and 10 Bq kg -1 in drinking water; those food materials above the limit cannot be sold. However, one of the most frequently asked questions from the public is how much radiocesium in food would be removed by processing. Hence, information about radioactivity removal by processing of food crops native to Japan is actively sought by consumers. In this study, the food processing retention factor, F r , which is expressed as total activity in processed food divided by total activity in raw food, is reported for various types of corps. For white rice at a typical polishing yield of 90-92% from brown rice, the F r value range was 0.42-0.47. For leafy vegetable (indirect contamination), the average F r values were 0.92 (range: 0.27-1.2) after washing and 0.55 (range: 0.22-0.93) after washing and boiling. The data for some fruits are also reported

Concentration, Soil-to-Plant Transfer Factor and Soil-Soil Solution Distribution Coefficient of Selenium in the Surface Environment -9106

ABSTRACT Of the major radioactive selenium isotopes, Se-79, a beta emitter with a half-life of about 1.1 million years, is of special interest because it is one of the most important radionuclides for the long-term dose assessment of radioactive waste disposal. This radionuclide can reach human beings through several transfer paths in the environment. To predict Se-79 behavior from the environment to human beings, it would be useful to obtain the following information: stable Se concentration in environmental samples; soil-soil solution distribution coefficient (K d ); and soil-to-plant transfer factor (TF). In the present study, stable Se concentrations in river water, soil and crop samples collected in Japan, K d s and TFs were obtained. The results showed that geometric mean (GM) concentrations of river water, soil and crops were 0.057 µg/L (range: <D.L.-1.17 µg/L), 0.43 mg/kg (range: 0.068-1.56 mg/kg-dry), and 0.015 mg/kg-dry (range: <D.L.-0.24 mg/kg-dry), respectively. GMs of K d s for paddy field soil and upland field soil samples were 116 and 67, respectively, whereas GMs of TFs for brown rice and upland field crops were 0.066 and 0.024, respectively. Probably due to longer growing period and different water management in the paddy fields for brown rice compared to those for upland field crops, the TF would be high in brown rice

Determination of U isotopic ratios in environmental samples by ICP-MS

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of trace elements in a variety of materials. For uranium, the concentration of 238U can be measured with a detection limit of less than 0.1 ppt in a few minutes. However, because of the extremely low 234U concentrations in environmental materials, it is necessary to separate U from the matrices and to remove interfering elements from the sample solution for measurement of the 238U/234U ratio by ICP-MS. In this study, a simple and rapid separation method for U with an extraction chromatographic resin (TEVA resin) was developed for ICP-MS and the U isotopic ratios in phosphogypsum samples, collected in Spain, were measured. The resin efficiently retained U in 6 M HCl medium and more than 98% of the U was easily eluted with the first 30 mL of 0.1 M HNO3. The separated solutions were free from most of the matrix elements and the concentrations of U in the solutions ranged from 35 to 70 ppb. The 238U/234U isotopic ratios in the solutions were measured by ICP-MS. Moreover, due to the presence of a higher number of 235U atoms in comparison with 234U, the 238U/235U isotopic ratios were also determined with high precision by ICP-MS. The results obtained agreed well with the ratios measured by alpha-spectrometry. The method for this determination is more rapid than alpha-spectrometry, and is considered to be more suitable for environmental monitoring

The time-dependent transfer factor of radiocesium from soil to game animals in Japan after the Fukushima Dai-ichi nuclear accident

Since the Fukushima Dai-ichi accident, monitoring of tissues from hunted game animals ensures compliance with the standard food limits for radionuclides in Japan. We quantified the transfer of 137Cs from contaminated land to game animals using the Aggregated transfer factor (Tag = activity concentration in meat [Bq kg–1 fw]/amount in soil [Bq m–2]) of 137Cs for Asian black bear, wild boar, sika deer, green pheasant, copper pheasant and wild duck, collected between 2011 and 2015. Open data sources were used from Fukushima, Miyagi, Ibaraki, Tochigi, and Gunma prefectures. Our initially compiled data showed that the maximum reported 137Cs activity concentration in wild boar after the Fukushima Dai-ichi accident were lower than those reported after the Chernobyl accident. The geometric mean Tag values (m2kg–1 fw) of 137Cs in 2015 for Asian black bear, wild boar, sika deer and copper pheasant were similar (1.9–5.1) × 10–3 while those for green pheasant and wild duck were about 1 order of magnitude lower at (1.0–2.2) × 10–4. Effective half-lives were 1.2–6.9 y except for sika deer and copper pheasant where no decreases were found. In contrast to the Chernobyl accident, no seasonal change occurred in the meat 137Cs activity concentrations of the wild animals during the study period

Changes in the soil to brown rice concentration ratio of radiocaesium before and after the Fukushima Daiichi nuclear power plant accident in 2011

Radiocaesium (RCs) mobility in soil is initially relatively high when the nuclide first comes into contact with soil, after which the mobile fraction decreases with time due to RCs fixation to soil particles (aging effect). Consequently, the RCs activity concentration in plants grown in soil was expected to decrease with time after the Fukushima Daiichi nuclear power plant accident in 2011. In this study, we collated data on concentration ratios (CR) of RCs between brown rice grain and paddy soil and compared CR values reported for periods before and after the accident. For this purpose, soil and rice data were collected after the accident specifically from paddy fields that did not have additional potassium fertilizer added (for remediation purposes). The geometric mean rice/soil CR of RCs for all types of soil was 1.2 × 10–2 in 2011 (n = 62) and by 2013 the value had declined to 3.5 × 10–3 (n = 32), which was similar to that for 1995–2007 of 3.4 × 10–3 (n = 120). The comparison suggests that the mean soil-to-rice grain concentration ratio had returned to that prevailing before the accident after less than three years. It was also confirmed that CR values for rice sampled from paddy fields were lower than those obtained from pot experiments

Vertical distributions of plutonium isotopes in marine sediment cores off the Fukushima coast after the Fukushima Dai-ichi Nuclear Power Plant accident

The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident led to the release of large amounts of radionuclides into the atmosphere as well as direct discharges into the sea. In contrast to the intensive studies on the distribution of the released high volatility fission products, such as 131I, 134Cs and 137Cs, similar studies of the actinides, especially the Pu isotopes, are limited. To obtain the vertical distribution of Pu isotopes in marine sediments and to better assess the possible contamination of Pu from the FDNPP accident in the marine environment, we determined the activities of 239+240Pu and 241Pu as well as the atom ratios of 240Pu/239Pu and 241Pu/239Pu in sediment core samples collected in the western North Pacific off Fukushima from July 2011 to July 2012. We also measured surface sediment samples collected from seven Japanese estuaries before the FNDPP accident to establish the comprehensive background baseline data. The observed results of both the Pu activities and the Pu atom ratios for the sediments in the western North Pacific were comparable to the baseline data, suggesting that the FDNPP accident did not cause detectable Pu contamination to the studied regions prior to the sampling time. The Pu isotopes in the western North Pacific 30 km off Fukushima coast originated from global fallout and Pacific Proving Ground close-in fallout

Isotopic evidence of plutonium release into the environment from the Fukushima DNPP accident

The Fukushima Daiichi nuclear power plant (DNPP) accident caused massive releases of radioactivity into the environment. The released highly volatile fission products, such as 129mTe, 131I, 134Cs, 136Cs and 137Cs were found to be widely distributed in Fukushima and its adjacent prefectures in eastern Japan. However, the release of non-volatile actinides, in particular, Pu isotopes remains uncertain almost one year after the accident. Here we report the isotopic evidence for the release of Pu into the atmosphere and deposition on the ground in northwest and south of the Fukushima DNPP in the 20–30 km zones. The high activity ratio of 241Pu/239+240Pu (> 100) from the Fukushima DNPP accident highlights the need for long-term 241Pu dose assessment, and the ingrowth of 241Am. The results are important for the estimation of reactor damage and have significant implication in the strategy of decontamination