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Resuming crop production in physically decontaminated fields affected by radiocesium ( 134 Cs and 137 Cs) releases is crucial for restoring impacted areas. However, surface soil excavation to reduce radiocesium may lead to lower crop yield due to the loss of fertile topsoil. This study aimed to assess the effects of cattle manure compost (CMC) application on soil properties, crop growth, and 137 Cs soil-to-crop transfer in a physically decontaminated field and pot experiment. Field trials were conducted during 2018-2022, with CMC (1 and 2 kg m -2  year -1 ) applied alongside conventional fertilization (CMC1 and CMC2 plots, respectively) in 2018-2019 and conventional fertilization alone in 2020-2022. Additionally, a pot experiment was used to evaluate the impact of CMC application in soil (1 kg m -2  year -1 for 5 years) on 137 Cs transfer. In the field trial during 2018-2019, CMC1 and CMC2 plots exhibited higher soybean shoot dry weight (DW) compared with plots receiving conventional fertilization and additional K fertilizer (+K 2 O). CMC application also improved soil nutrient content. The transfer factor of 137 Cs (TF- 137 Cs: plant 137 Cs activity concentration/soil 137 Cs activity concentration) followed the order CMC2 < CMC1 ≈ +K 2 O < conventional fertilization only (CF) and was negatively correlated with soil exchangeable K (Ex-K). During 2020-2022, when all plots received conventional fertilization alone, grain yields were higher in CMC1 and CMC2 plots than in the +K 2 O plot, with the lowest TF- 137 Cs in CMC2 plot followed by CMC1, +K 2 O, and CF plots. The pot experiment confirmed that CMC soil had a lower TF- 137 Cs and higher plant DW compared with CF soil with the same Ex-K level. Additionally, the soil exchangeable 137 Cs (Ex- 137 Cs) level was significantly lower in CMC soil than CF soil. These findings demonstrate the potential of CMC application to improve crop growth and reduce 137 Cs transfer in physically decontaminated fields., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Ceasium-137 and 90 Sr are major artificial radionuclides that have been released into the environment. Soil-to-plant transfer of radionuclides is an important route to food contamination. The radionuclide activity concentrations in crops must be quantitatively predicted for estimating the internal radiation doses from food ingestion. In this study, soil and potato samples were collected from three study sites contaminated with different sources of 137 Cs and 90 Sr: Aomori Prefecture (global fallout) and two accidental release areas (Fukushima Prefecture and the Chornobyl exclusion zone). The 137 Cs activity concentrations in the soil and potato samples widely ranged from 1.0 to 250,000 and from 0.048 to 200,000 Bq kg -1 dry weight, respectively. The soil-to-potato transfer factor of 137 Cs also ranged widely (0.0015-1.1) and decreased with increasing concentration of exchangeable K. Meanwhile, the activity concentrations of 90 Sr in the soil and potato samples were 0.50-64,000 and 0.027-18,000 Bq kg -1 dry weight respectively, and the soil-to-potato transfer factor of 90 Sr was 0.023-0.74, decreasing with increasing concentration of exchangeable Ca. The specific activity ratios of 137 Cs/Cs and 90 Sr/Sr in the exchangeable fraction were similar to those in potatoes, with a factor of 3 in the ±95 % confidence intervals over six orders of magnitude and a factor of 2 in the ±95 % confidence intervals over five orders of magnitude, respectively. According to the data, the accuracy of predicting the activity concentrations of 137 Cs and 90 Sr in potatoes can be improved by applying the specific activity ratios of 137 Cs/Cs and 90 Sr/Sr in the exchangeable fraction. This approach accounts for variable factors such as the effects of K and Ca fertilization and soil characteristics. It also emphasizes the benefit of determining the stable Cs and Sr concentrations in potatoes and other crops prior to possible future contamination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Despite the presence of minerals that allow Cs fixation in soils, 137 Cs remains available to crops for several years after its deposition, particularly in pasture soils. Larger amounts of organic matter derived from herbage residues are accumulated in pasture soils than in tilled farmland soils. As the above-ground part of herbage crops initially received airborne 137 Cs during the accident at Fukushima Daiich nuclear power plant (FDNPP), the organic matter originated from the contaminated herbage should play an important role in the fate of 137 Cs in soils. To evaluate the role of organic matter on 137 Cs distribution between potentially mobile and immobile fractions, we compared the distribution of 137 Cs and stable 133 Cs, which are differently associated with organic matter, by sequential extraction and density fractionation. Soil samples were collected 8 years after the accident from Andosols in pasture fields located about 160 km southwest of FDNPP. More than 90% of 137 Cs was not extracted even after oxidative digestion of organic matter, suggesting that most 137 Cs was strongly associated with soil minerals. Density fractionation results showed that the 137 Cs/ 133 Cs ratio was highest in the density fraction of 1.6-1.8 g cm -3 , in which organic matter -including fragmented and decomposed plant detritus -was associated with minerals. Mineral-free organic matter, mostly composed of fresh plant detritus (<1.6 g cm -3 ), had a higher 137 Cs/ 133 Cs ratio than that of crops harvested in the same year of soil sampling. Thus, the transfer of 137 Cs from soil to plants decreased with cultivation cycles. Our results demonstrate that plant-available 137 Cs in pasture soil decreased with aging time, not only through increased 137 Cs fixation in mineral-dominated fractions but also through its physical sequestration in aggregates., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

After the 2011 Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident, wild populations of animals and plants living in the evacuation zone received additional ionizing radiation of both internal and external radiation doses. Morphological abnormalities of pine and fir trees near the FDNPS were reported. In order to evaluate dose-effect relationships, it is necessary to quantify the radiation doses to trees and plants. In this study, the internal and external dose rates to Japanese cedar and plants collected at three sites in Okuma, approximately 4 km southwest of FDNPS were estimated applying the ERICA Assessment Tool. The activity concentrations of 134 Cs and 137 Cs in soils, cedar trunks, and plants were determined. The total dose rates to cedar ranged from 2.2 ± 1.2 to 6.1 ± 2.2 μGy h -1 . These rates were within the derived consideration reference levels (DCRLs) reported by ICRP 108 as 4-40 μGy h -1 for pine trees. The highest estimate for plants was 7.1 ± 2.7 μGy h -1 , much smaller than the DCRLs reported for grasses and herbs (40-400 μGy h -1 ). On average, the internal radiation dose rates to cedars at the two sites accounted for 5% and 29% of the external dose rates, respectively, while the value in another site was only 0.4% for cedar. This was attributed to differences in the crown area between the three sites. The trunk diameter of cedars shows a positive correlation with the ratio of internal to external radiation dose rates. It indicates that the total dose rate to cedars is easily estimated with the soil radiocaesium inventory and trunk diameter. The internal radiation dose rate to the plant varied depending on the plant species. This variation was considerably large in plants due to the presence of two species, including Solidago altissima and Artemisia indica var. maximowiczii., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

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 241 Pu/ 239 Pu atom ratios. In contrast, other typically-used Pu measures ( 240 Pu/ 239 Pu 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 134,137 Cs 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 239 Pu and was distinguished by both 240 Pu/ 239 Pu and 241 Pu/ 239 Pu 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 241 Pu/ 239 Pu 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., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Crown Copyright © 2020. Published by Elsevier B.V. All rights reserved.)

Due to radioisotope releases in the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, long-term monitoring of radiocesium ((135)Cs and (137)Cs) and Pu isotopes ((239)Pu and (240)Pu) in river suspended particles is necessary to study the transport and fate of these long-lived radioisotopes in the land-ocean system. However, it is expensive and technically difficult to collect samples of suspended particles from river and ocean. Thus, simultaneous determination of multi-radionuclides remains as a challenging topic. In this study, for the first time, we report an analytical method for simultaneous determination of radiocesium and Pu isotopes in suspended particles with small sample size (1-2g). Radiocesium and Pu were sequentially pre-concentrated using ammonium molybdophosphate and ferric hydroxide co-precipitation, respectively. After the two-stage ion-exchange chromatography separation from the matrix elements, radiocesium and Pu isotopes were finally determined by ICP-MS/MS and SF-ICP-MS, respectively. The interfering elements of U ((238)U(1)H(+) and (238)U(2)H(+) for (239)Pu and (240)Pu, respectively) and Ba ((135)Ba(+) and (137)Ba(+) for (135)Cs and (137)Cs, respectively) were sufficiently removed with the decontamination factors of 1-8×10(6) and 1×10(4), respectively, with the developed method. Soil reference materials were utilized for method validation, and the obtained (135)Cs/(137)Cs and (240)Pu/(239)Pu atom ratios, and (239+240)Pu activities showed a good agreement with the certified/information values. In addition, the developed method was applied to analyze radiocesium and Pu in the suspended particles of land water samples collected from Fukushima Prefecture after the FDNPP accident. The (135)Cs/(137)Cs atom ratios (0.329-0.391) and (137)Cs activities (23.4-152Bq/g) suggested radiocesium contamination of the suspended particles mainly originated from the accident-released radioactive contaminates, while similar Pu contamination of suspended particles caused by the accident could be neglected as the (240)Pu/(239)Pu atom ratios (0.182-0.208) were within the range of global fallout., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The U concentrations in the soils of experimental fields with continuous fertilizer applications and in neighboring non-agricultural soils were determined. The surface soils in the three experimental fields with fertilizer applications contained higher amounts of U compared with the non-agricultural surface soils. The amount of U elevated in the soil was estimated by the vertical profile of U concentration, and an increase of about 200 mg m-2 of U was found in the soils at 0-35 cm depth during a 61-year cultivation period. The estimated value was almost the same as the amount of U added through the fertilizers as calculated from U concentrations in the applied fertilizers. Therefore, almost all the U from the fertilizers would still remain in the upper part of the soils. Chemical extraction results suggested that organic substances and noncrystalline clay minerals in the surface soil should play an important role for accumulation of U derived from the fertilizers.