Pub Date : 2026-01-09DOI: 10.1016/j.jenvrad.2026.107900
Ryu Yoshida , Hiroshi Kurikami , Fumiya Nagao , Shigeo Takahashi , Yukihisa Sanada
Following the Fukushima Daiichi Nuclear Power Station accident in 2011, ambient dose rates in the surrounding region initially increased due to the deposition of radioactive materials on the ground, and have subsequently continued to decline owing to radioactive decay and decontamination efforts to the present. However, spatial variations in dose rate reduction remain insufficiently understood, particularly in forested areas where contamination persists. In this study, long-term trends in ambient dose rate changes were investigated using explainable AI techniques. An integrated dose rate map comprising fixed-point, walk, carborne, and airborne survey data collected over 12 years was used to analyze temporal and spatial patterns. We developed a predictive model using the Light Gradient Boosting Machine framework to estimate dose rate reduction ratios based on geographic and environmental features. SHapley Additive exPlanations were applied to quantify the contribution of each variable and enhance model interpretability. Our findings revealed that land use significantly influences dose rate reduction, with urban and agricultural areas showing faster reduction because of infrastructure and human activity, including decontamination work, whereas forests exhibit slower reduction. Notably, topographical features, such as elevation and slope, affect dose rate trends in undisturbed forests, with valleys and depressions showing stagnation. This paper provides the first visual validation of area-wide decontamination effects and demonstrates the utility of explainable AI in environmental radiation analysis. The proposed approach offers a robust framework for geospatial interpretation and, with further verification, is expected to support informed policymaking for regional recovery and forest utilization.
{"title":"Ambient dose rate variation in the Fukushima region visualized using explainable AI techniques","authors":"Ryu Yoshida , Hiroshi Kurikami , Fumiya Nagao , Shigeo Takahashi , Yukihisa Sanada","doi":"10.1016/j.jenvrad.2026.107900","DOIUrl":"10.1016/j.jenvrad.2026.107900","url":null,"abstract":"<div><div>Following the Fukushima Daiichi Nuclear Power Station accident in 2011, ambient dose rates in the surrounding region initially increased due to the deposition of radioactive materials on the ground, and have subsequently continued to decline owing to radioactive decay and decontamination efforts to the present. However, spatial variations in dose rate reduction remain insufficiently understood, particularly in forested areas where contamination persists. In this study, long-term trends in ambient dose rate changes were investigated using explainable AI techniques. An integrated dose rate map comprising fixed-point, walk, carborne, and airborne survey data collected over 12 years was used to analyze temporal and spatial patterns. We developed a predictive model using the Light Gradient Boosting Machine framework to estimate dose rate reduction ratios based on geographic and environmental features. SHapley Additive exPlanations were applied to quantify the contribution of each variable and enhance model interpretability. Our findings revealed that land use significantly influences dose rate reduction, with urban and agricultural areas showing faster reduction because of infrastructure and human activity, including decontamination work, whereas forests exhibit slower reduction. Notably, topographical features, such as elevation and slope, affect dose rate trends in undisturbed forests, with valleys and depressions showing stagnation. This paper provides the first visual validation of area-wide decontamination effects and demonstrates the utility of explainable AI in environmental radiation analysis. The proposed approach offers a robust framework for geospatial interpretation and, with further verification, is expected to support informed policymaking for regional recovery and forest utilization.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"293 ","pages":"Article 107900"},"PeriodicalIF":2.1,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.jenvrad.2025.107877
Alinne Marianne Martins Araújo , Laercio Leal dos Santos , Beata Kozłowska , Agata Walencik-Łata , Ricardo de Aragão , de Paiva William , Antônio Augusto Pereira Sousa , Thyago Nobrega Silveira , Alan Kellnon Nóbrega Carvalho , Elibe Silva Souza , Josenildo Isidro dos Santos Filho , Susana de Souza Lalic
<div><div>To close a critical evidence gap in Brazil's semi-arid Northeast, where groundwater-quality data remain scarce, we established an integrated hydrochemical–radiological baseline for Parelhas (Seridó Belt, NE Brazil), an area with uranium potential in the Seridó region of Brazil that is susceptible to drought. The assessment focuses on physical-chemical and radiological parameters to determine the suitability of water for human consumption. This preliminary research presents analyses of nine wells sampled between March and August 2023. Major ions and trace metals were determined using AAS/ICP and anions by IC/UV–Vis. The pH, electrical conductivity, temperature, and total dissolved solids (TDS) were measured in situ. The activity concentrations of <sup>226,228</sup>Ra isotopes were measured with a Tri-Carb 5110 TR liquid scintillation counter (LSC). The results revealed neutral to strongly alkaline conditions (pH 6.9–10.1) and from fresh to highly saline (TDS 476–3632 mg L<sup>−1</sup>; 40 % brackish), driven by evaporative enrichment (Na-Cl facies; Gibbs ratio >0.7) and weathering of local lithologies (Jucurutu and Seridó Formations). Salinity covaried with geogenic metals and halides: Cl<sup>−</sup> 180–2021 mg L<sup>−1</sup>, Na<sup>+</sup> 84–690 mg L<sup>−1</sup>, K<sup>+</sup> 3.4–29.6 mg L<sup>−1</sup>, Ca<sup>2+</sup> 3.6–120.8 mg L<sup>−1</sup>, Mg<sup>2+</sup> 2.2–264 mg L<sup>−1</sup>, and SO<sub>4</sub><sup>2−</sup> 0–195 mg L<sup>−1</sup>. F<sup>−</sup> varied from 0.07 to 3.18 mg L<sup>−1</sup> (two wells >1.5 mg L<sup>−1</sup>), and NO<sub>3</sub><sup>−</sup> from 2.3 to 275.5 mg L<sup>−1</sup> (several wells >50 mg L<sup>−1</sup>). Peak trace-metal concentrations reached Mn 2.334 mg L<sup>−1</sup>, Al 291 μg L<sup>−1</sup>, Pb 31 μg L<sup>−1</sup>, and Zn 215 μg L<sup>−1</sup> — exceeded aesthetic limits, posing non-carcinogenic risks. Piper diagrams place the waters in the Na–Cl to Na–HCO<sub>3</sub> fields, while Gibbs diagrams indicate evaporation-dominated control; negative chlorine-alkaline indices (CAI <0) point to reverse ion exchange (Na<sup>+</sup> ↔ Ca<sup>2+</sup>/Mg<sup>2+</sup>) against the micaceous-schist matrix, modulating the chemistry of the cations. Radiologically, <sup>226</sup>Ra ranged from 30 to 930 mBq·L<sup>−1</sup> (≤∼1 Bq· L<sup>−1</sup> screening level), while for the <sup>228</sup>Ra isotope, the concentrations for most samples were below the detection level. Only two samples showed <sup>228</sup>Ra concentrations above Minimum Detectable Activity (55 mBq·L<sup>−1</sup>). The dataset shows that climate forcing (evaporation) and not just water-rock interaction controls salinity and the co-mobilization of halides and trace metals in this semi-arid aquifer. Spatial analysis associated critical contamination points with uranium anomalies and fractured aquifers. The findings demonstrate that climatic forces (evaporation) prevail over water–rock interaction in controlling hydrochemistry,
{"title":"Integrated hydrochemical and radiological assessment of groundwater in the Seridó crystalline basement (Brazil): Evidence of geogenic influences on 226,228Ra and trace elements","authors":"Alinne Marianne Martins Araújo , Laercio Leal dos Santos , Beata Kozłowska , Agata Walencik-Łata , Ricardo de Aragão , de Paiva William , Antônio Augusto Pereira Sousa , Thyago Nobrega Silveira , Alan Kellnon Nóbrega Carvalho , Elibe Silva Souza , Josenildo Isidro dos Santos Filho , Susana de Souza Lalic","doi":"10.1016/j.jenvrad.2025.107877","DOIUrl":"10.1016/j.jenvrad.2025.107877","url":null,"abstract":"<div><div>To close a critical evidence gap in Brazil's semi-arid Northeast, where groundwater-quality data remain scarce, we established an integrated hydrochemical–radiological baseline for Parelhas (Seridó Belt, NE Brazil), an area with uranium potential in the Seridó region of Brazil that is susceptible to drought. The assessment focuses on physical-chemical and radiological parameters to determine the suitability of water for human consumption. This preliminary research presents analyses of nine wells sampled between March and August 2023. Major ions and trace metals were determined using AAS/ICP and anions by IC/UV–Vis. The pH, electrical conductivity, temperature, and total dissolved solids (TDS) were measured in situ. The activity concentrations of <sup>226,228</sup>Ra isotopes were measured with a Tri-Carb 5110 TR liquid scintillation counter (LSC). The results revealed neutral to strongly alkaline conditions (pH 6.9–10.1) and from fresh to highly saline (TDS 476–3632 mg L<sup>−1</sup>; 40 % brackish), driven by evaporative enrichment (Na-Cl facies; Gibbs ratio >0.7) and weathering of local lithologies (Jucurutu and Seridó Formations). Salinity covaried with geogenic metals and halides: Cl<sup>−</sup> 180–2021 mg L<sup>−1</sup>, Na<sup>+</sup> 84–690 mg L<sup>−1</sup>, K<sup>+</sup> 3.4–29.6 mg L<sup>−1</sup>, Ca<sup>2+</sup> 3.6–120.8 mg L<sup>−1</sup>, Mg<sup>2+</sup> 2.2–264 mg L<sup>−1</sup>, and SO<sub>4</sub><sup>2−</sup> 0–195 mg L<sup>−1</sup>. F<sup>−</sup> varied from 0.07 to 3.18 mg L<sup>−1</sup> (two wells >1.5 mg L<sup>−1</sup>), and NO<sub>3</sub><sup>−</sup> from 2.3 to 275.5 mg L<sup>−1</sup> (several wells >50 mg L<sup>−1</sup>). Peak trace-metal concentrations reached Mn 2.334 mg L<sup>−1</sup>, Al 291 μg L<sup>−1</sup>, Pb 31 μg L<sup>−1</sup>, and Zn 215 μg L<sup>−1</sup> — exceeded aesthetic limits, posing non-carcinogenic risks. Piper diagrams place the waters in the Na–Cl to Na–HCO<sub>3</sub> fields, while Gibbs diagrams indicate evaporation-dominated control; negative chlorine-alkaline indices (CAI <0) point to reverse ion exchange (Na<sup>+</sup> ↔ Ca<sup>2+</sup>/Mg<sup>2+</sup>) against the micaceous-schist matrix, modulating the chemistry of the cations. Radiologically, <sup>226</sup>Ra ranged from 30 to 930 mBq·L<sup>−1</sup> (≤∼1 Bq· L<sup>−1</sup> screening level), while for the <sup>228</sup>Ra isotope, the concentrations for most samples were below the detection level. Only two samples showed <sup>228</sup>Ra concentrations above Minimum Detectable Activity (55 mBq·L<sup>−1</sup>). The dataset shows that climate forcing (evaporation) and not just water-rock interaction controls salinity and the co-mobilization of halides and trace metals in this semi-arid aquifer. Spatial analysis associated critical contamination points with uranium anomalies and fractured aquifers. The findings demonstrate that climatic forces (evaporation) prevail over water–rock interaction in controlling hydrochemistry, ","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"293 ","pages":"Article 107877"},"PeriodicalIF":2.1,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To address the issue of radon contamination in uranium tailings ponds, this study aimed to enhance the radon reduction performance of the enzyme-induced calcium carbonate precipitation (EICP) coating layer. This study employed uranium tailings irradiation to regulate soybean urease activity. By analyzing the irradiation effects of tailings at different burial depths and combining X-ray diffraction (XRD) with scanning electron microscopy (SEM) for multi-scale characterization, the study systematically reveals the microscopic radon reduction mechanisms. Experimental results show that the treatment with soybean urease from tailings irradiated at a depth of 3–4 m, for three days, achieved a radon reduction rate of 97 % after 28 days of curing, representing 17.1 % higher than that of traditional red clay. Microscopic structural analysis confirmed the formation of stable calcite and flocculent cementation within the material, reducing porosity and enhancing densification to effectively block radon migration pathways. The above experimental results validated the effectiveness of the irradiation-urease activity synergistic enhancement mechanism for radon reduction, providing theoretical guidance for efficient radon reduction engineering in radioactive solid waste landfills.
{"title":"Study on the irradiation control of urease activity and its solidification of red clay to enhance radon reduction","authors":"Yuanyuan Tang, Rui Liang, Jia Wei, Yiqing Sun, Weihang Peng, Fubing Li, Chengyu Zhang, Changshou Hong","doi":"10.1016/j.jenvrad.2025.107879","DOIUrl":"10.1016/j.jenvrad.2025.107879","url":null,"abstract":"<div><div>To address the issue of radon contamination in uranium tailings ponds, this study aimed to enhance the radon reduction performance of the enzyme-induced calcium carbonate precipitation (EICP) coating layer. This study employed uranium tailings irradiation to regulate soybean urease activity. By analyzing the irradiation effects of tailings at different burial depths and combining X-ray diffraction (XRD) with scanning electron microscopy (SEM) for multi-scale characterization, the study systematically reveals the microscopic radon reduction mechanisms. Experimental results show that the treatment with soybean urease from tailings irradiated at a depth of 3–4 m, for three days, achieved a radon reduction rate of 97 % after 28 days of curing, representing 17.1 % higher than that of traditional red clay. Microscopic structural analysis confirmed the formation of stable calcite and flocculent cementation within the material, reducing porosity and enhancing densification to effectively block radon migration pathways. The above experimental results validated the effectiveness of the irradiation-urease activity synergistic enhancement mechanism for radon reduction, providing theoretical guidance for efficient radon reduction engineering in radioactive solid waste landfills.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"293 ","pages":"Article 107879"},"PeriodicalIF":2.1,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145917701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-02DOI: 10.1016/j.jenvrad.2025.107885
João M.F. Lopes , Fábio L. Melquiades , Rodrigo O. Bastos , Angelo Z. Neto , Avacir C. Andrello
Gamma-ray spectrometry is a non-destructive technique that may be employed on several types of samples to perform radiation measurements and radionuclide quantification. Different kinds of detectors may present different efficiencies and resolutions, which may lead to difficulties in measuring and quantifying particular radionuclides. To compensate for these difficulties, this work focuses on the feasibility of applying a calibration transfer methodology between a NaI(Tl) and a HPGe detector. The method employed was Target Transformation Factor Analysis, and its performance was evaluated using Root Mean Squared Error and Mean Absolute Error. Both coefficients indicated that the calculated transformation matrix performs well, and this kind of methodology is suitable for gamma-ray spectrometry measurements. Moreover, 7Be, 40K, 137Cs, 208Tl and 214Bi were quantified in all 41 soil samples using the HPGe, NaI(Tl), and transformed spectra. The comparison of the results obtained with the three sets of spectra revealed statistically insignificant differences. Furthermore, the Mean Difference, Mean Absolute Error, and Mean Bias Error between the transformed and HPGe spectra indicate that the application of TTFA significantly enhances the results in comparison with the original NaI(Tl) spectra.
{"title":"Calibration transfer from HPGe to NaI(Tl) detectors for radionuclides quantification","authors":"João M.F. Lopes , Fábio L. Melquiades , Rodrigo O. Bastos , Angelo Z. Neto , Avacir C. Andrello","doi":"10.1016/j.jenvrad.2025.107885","DOIUrl":"10.1016/j.jenvrad.2025.107885","url":null,"abstract":"<div><div>Gamma-ray spectrometry is a non-destructive technique that may be employed on several types of samples to perform radiation measurements and radionuclide quantification. Different kinds of detectors may present different efficiencies and resolutions, which may lead to difficulties in measuring and quantifying particular radionuclides. To compensate for these difficulties, this work focuses on the feasibility of applying a calibration transfer methodology between a NaI(Tl) and a HPGe detector. The method employed was Target Transformation Factor Analysis, and its performance was evaluated using Root Mean Squared Error and Mean Absolute Error. Both coefficients indicated that the calculated transformation matrix performs well, and this kind of methodology is suitable for gamma-ray spectrometry measurements. Moreover, <sup>7</sup>Be, <sup>40</sup>K, <sup>137</sup>Cs, <sup>208</sup>Tl and <sup>214</sup>Bi were quantified in all 41 soil samples using the HPGe, NaI(Tl), and transformed spectra. The comparison of the results obtained with the three sets of spectra revealed statistically insignificant differences. Furthermore, the Mean Difference, Mean Absolute Error, and Mean Bias Error between the transformed and HPGe spectra indicate that the application of TTFA significantly enhances the results in comparison with the original NaI(Tl) spectra.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"293 ","pages":"Article 107885"},"PeriodicalIF":2.1,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145876917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.jenvrad.2025.107884
Pawan Kumar, Stellan Holgersson, Christian Ekberg
The sorption of 134Cs, 133Ba, 60Co and 152Eu onto crushed biotite mineral of size fraction 0.25–0.5 mm at pH 5, 6, 7, 8 and 9 with pH-buffered solutions of 0.001, 0.01 and 0.1 M NaClO4 were investigated. Experimental data was collected by both batch sorption and potentiometric titrations, together with measurements of the acidic site density and cation exchange capacity of the biotite. Titrations gave biotite surface pKa1 = −4.9 ± 0.1 and pKa2 = −7.1 ± 0.2. Batch sorption results show that sorption of all radionuclides is highly dependent on pH. In general sorption increase with pH, but for Co its aqueous hydroxide complexes compete with sorption at pH values > 8 while for Eu, this competition starts at pH > 7. Sorption of both Cs and Ba is strongly dependent on ionic strength, Eu shows an intermediate response while Co was found to be insensitive to this parameter. The measured apparent Rd values were found to increase with time, presumably due to in-diffusion. Therefore, equilibrium Rd was evaluated with a new model for diffusion into porous particles. A non-electrostatic Surface Complexation Model (SCM) was applied on the sorption data and the reaction constants were evaluated in a computation process which couples the PHREEQC chemical speciation program with an iterative error minimization routine. The sorption onto biotite of all four tracer elements was successfully modelled with a combination of one amphoteric 2-pKa surface complexation site and one ion exchange site. The results show that the Rd-values may vary up to two orders of magnitude, depending on tracer element and water conditions. Such large changes should be considered in the safety evaluation of a repository in granitic rock, more specifically for scenarios where groundwater composition is expected to change.
在pH为5、6、7、8和9的条件下，用pH缓冲溶液0.001、0.01和0.1 M NaClO4，研究了粒径为0.25 ~ 0.5 mm的破碎黑云母矿物对134Cs、133Ba、60Co和152Eu的吸附。实验数据的收集采用了批吸附法和电位滴定法，并测量了黑云母的酸性位点密度和阳离子交换容量。滴定得到黑云母表面pKa1 = -4.9±0.1和pKa2 = -7.1±0.2。批吸附结果表明，所有放射性核素的吸附都高度依赖于pH值。一般情况下，吸附随pH值的增加而增加，但对于Co，其水溶液氢氧化物络合物在pH值bbbb8时与吸附竞争，而对于Eu，这种竞争从pH值bbbb7开始。Cs和Ba的吸附都强烈依赖于离子强度，Eu表现出中间响应，而Co对该参数不敏感。测得的表观Rd值随着时间的推移而增加，可能是由于内扩散。因此，用一种新的扩散到多孔颗粒中的模型来评估平衡Rd。采用非静电表面络合模型（SCM）对吸附数据进行处理，并结合PHREEQC化学形态分析程序和迭代误差最小化程序计算反应常数。通过一个两性2-pKa表面络合位点和一个离子交换位点的组合，成功地模拟了四种示踪元素在黑云母上的吸附。结果表明，根据示踪元素和水条件的不同，rd值的变化可达两个数量级。在对花岗岩储存库进行安全评价时，特别是在地下水成分预计会发生变化的情况下，应考虑到这种大的变化。
{"title":"Cs, Ba, Co, and Eu sorption on biotite - experiments at ambient temperature and modelling","authors":"Pawan Kumar, Stellan Holgersson, Christian Ekberg","doi":"10.1016/j.jenvrad.2025.107884","DOIUrl":"10.1016/j.jenvrad.2025.107884","url":null,"abstract":"<div><div>The sorption of <sup>134</sup>Cs, <sup>133</sup>Ba, <sup>60</sup>Co and <sup>152</sup>Eu onto crushed biotite mineral of size fraction 0.25–0.5 mm at pH 5, 6, 7, 8 and 9 with pH-buffered solutions of 0.001, 0.01 and 0.1 M NaClO<sub>4</sub> were investigated. Experimental data was collected by both batch sorption and potentiometric titrations, together with measurements of the acidic site density and cation exchange capacity of the biotite. Titrations gave biotite surface <em>pK</em><sub><em>a1</em></sub> = −4.9 ± 0.1 and <em>pK</em><sub><em>a2</em></sub> = −7.1 ± 0.2. Batch sorption results show that sorption of all radionuclides is highly dependent on pH. In general sorption increase with pH, but for Co its aqueous hydroxide complexes compete with sorption at pH values > 8 while for Eu, this competition starts at pH > 7. Sorption of both Cs and Ba is strongly dependent on ionic strength, Eu shows an intermediate response while Co was found to be insensitive to this parameter. The measured apparent <em>R</em><sub><em>d</em></sub> values were found to increase with time, presumably due to in-diffusion. Therefore, equilibrium <em>R</em><sub><em>d</em></sub> was evaluated with a new model for diffusion into porous particles. A non-electrostatic Surface Complexation Model (SCM) was applied on the sorption data and the reaction constants were evaluated in a computation process which couples the PHREEQC chemical speciation program with an iterative error minimization routine. The sorption onto biotite of all four tracer elements was successfully modelled with a combination of one amphoteric 2-<em>pK</em><strong><sub><em>a</em></sub></strong> surface complexation site and one ion exchange site. The results show that the <em>R</em><sub><em>d</em></sub>-values may vary up to two orders of magnitude, depending on tracer element and water conditions. Such large changes should be considered in the safety evaluation of a repository in granitic rock, more specifically for scenarios where groundwater composition is expected to change.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"292 ","pages":"Article 107884"},"PeriodicalIF":2.1,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145862449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-26DOI: 10.1016/j.jenvrad.2025.107865
B. Christensen , S. Ozerov , D. DiPrete , D. McAlister , R.P. Taleyarkhan
Studies were conducted to demonstrate the ability to directly extract U from pure and saline waters and then rapidly detect trace (0.02–0.2 mBq/mL) gross alpha particle emissions using centrifugally tensioned metastable fluid detectors (CTMFDs), which enable 4π (∼99 %) intrinsic alpha detection efficiency with keV-level resolution, while also exhibiting insensitivity to gamma and beta radiation. Actinide resin-extractant cartridges were used to extract U (in fresh and saline water) and Pu (in fresh water). A CTMFD-specific protocol was developed to remove the extractant and actinide from the cartridge, flushing with methanol and transferring into the CTMFD's sensing fluid, decafluoropentane (DFP), allowing gross alpha assay within hours. Effects of volumetric flow rate through the cartridge, actinide concentration, sensing fluid precompression, and salinity were assessed. The studies demonstrated the ability to reproducibly detect actinide content in deionized and saline (3.5 w% sea salt) water at levels commensurate with USEPA's minimum detectable activity (MDA) target levels, with uncertainty levels of 0.05 mBq/mL (0.2 pCi/L) range. The resulting method allowed direct extraction and reproducible monitoring within hours for actinides in 0.01M HNO3 water at varying efficiencies- For U: ∼96 % (no salt); ∼80 % (3.5 w% sea salt); ∼10–20 % (salt with infused additives). For Pu: ∼60–80 % (non-saline).
{"title":"Direct extraction and high efficiency gross alpha detection of trace-level U or Pu actinides in deionized and saline water samples with CTMFDs","authors":"B. Christensen , S. Ozerov , D. DiPrete , D. McAlister , R.P. Taleyarkhan","doi":"10.1016/j.jenvrad.2025.107865","DOIUrl":"10.1016/j.jenvrad.2025.107865","url":null,"abstract":"<div><div>Studies were conducted to demonstrate the ability to directly extract U from pure and saline waters and then rapidly detect trace (0.02–0.2 mBq/mL) gross alpha particle emissions using centrifugally tensioned metastable fluid detectors (CTMFDs), which enable 4π (∼99 %) intrinsic alpha detection efficiency with keV-level resolution, while also exhibiting insensitivity to gamma and beta radiation. Actinide resin-extractant cartridges were used to extract U (in fresh and saline water) and Pu (in fresh water). A CTMFD-specific protocol was developed to remove the extractant and actinide from the cartridge, flushing with methanol and transferring into the CTMFD's sensing fluid, decafluoropentane (DFP), allowing gross alpha assay within hours. Effects of volumetric flow rate through the cartridge, actinide concentration, sensing fluid precompression, and salinity were assessed. The studies demonstrated the ability to reproducibly detect actinide content in deionized and saline (3.5 w% sea salt) water at levels commensurate with USEPA's minimum detectable activity (MDA) target levels, with uncertainty levels of 0.05 mBq/mL (0.2 pCi/L) range. The resulting method allowed direct extraction and reproducible monitoring within hours for actinides in 0.01M HNO<sub>3</sub> water <u>at varying efficiencies</u>- For U: ∼96 % (no salt); ∼80 % (3.5 w% sea salt); ∼10–20 % (salt with infused additives). For Pu: ∼60–80 % (non-saline).</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"292 ","pages":"Article 107865"},"PeriodicalIF":2.1,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To accurately predict the long-term dynamics of radiocesium (137Cs) in forests contaminated by the nuclear accident, it is important to monitor 137Cs fluxes in forest ecosystems more than ten years after the accident. Among these fluxes, 137Cs transfer via litterfall—a major pathway by which trees return 137Cs to the soil—is one of the key processes to observe. However, in forests more than a decade after the Fukushima accident, observations of litterfall remain limited, and the extent of site-to-site variation has not been evaluated. In this study, we conducted new observations of litterfall over a two-year period from December 1, 2022, to November 28 or 29, 2024, at three Japanese cedar forest sites and three deciduous broad-leaved forest sites in Fukushima Prefecture, and obtained annual 137Cs fluxes via litterfall. Our results revealed that, in Japanese cedar forests, between 0.080% and 0.29% of the initial 137Cs deposition was transferred via litterfall, whereas in deciduous broad-leaved forests, the proportion ranged from 0.22% to 0.37%. Based on the evaluation of site-to-site variation using box plots, including previously reported values, the median proportion of 137Cs flux via litterfall relative to the initial deposition was 0.29% (95% confidence interval: 0.11–0.77%) in Japanese cedar forests and 0.33% (95% confidence interval: 0.27–0.41%) in deciduous broad-leaved forests. The results also indicated that the site-to-site variation tended to be relatively greater in Japanese cedar forests. These findings are expected to support modeling efforts aimed at predicting the distribution of 137Cs in forest ecosystems by providing a basis for evaluating the variability and uncertainty of 137Cs transfer between trees and soil as model parameters.
{"title":"Inter-site comparison of radiocesium flux via litterfall more than a decade after the Fukushima nuclear accident","authors":"Wataru Sakashita , Satoru Miura , Yoshiki Shinomiya","doi":"10.1016/j.jenvrad.2025.107880","DOIUrl":"10.1016/j.jenvrad.2025.107880","url":null,"abstract":"<div><div>To accurately predict the long-term dynamics of radiocesium (<sup>137</sup>Cs) in forests contaminated by the nuclear accident, it is important to monitor <sup>137</sup>Cs fluxes in forest ecosystems more than ten years after the accident. Among these fluxes, <sup>137</sup>Cs transfer via litterfall—a major pathway by which trees return <sup>137</sup>Cs to the soil—is one of the key processes to observe. However, in forests more than a decade after the Fukushima accident, observations of litterfall remain limited, and the extent of site-to-site variation has not been evaluated. In this study, we conducted new observations of litterfall over a two-year period from December 1, 2022, to November 28 or 29, 2024, at three Japanese cedar forest sites and three deciduous broad-leaved forest sites in Fukushima Prefecture, and obtained annual <sup>137</sup>Cs fluxes via litterfall. Our results revealed that, in Japanese cedar forests, between 0.080% and 0.29% of the initial <sup>137</sup>Cs deposition was transferred via litterfall, whereas in deciduous broad-leaved forests, the proportion ranged from 0.22% to 0.37%. Based on the evaluation of site-to-site variation using box plots, including previously reported values, the median proportion of <sup>137</sup>Cs flux via litterfall relative to the initial deposition was 0.29% (95% confidence interval: 0.11–0.77%) in Japanese cedar forests and 0.33% (95% confidence interval: 0.27–0.41%) in deciduous broad-leaved forests. The results also indicated that the site-to-site variation tended to be relatively greater in Japanese cedar forests. These findings are expected to support modeling efforts aimed at predicting the distribution of <sup>137</sup>Cs in forest ecosystems by providing a basis for evaluating the variability and uncertainty of <sup>137</sup>Cs transfer between trees and soil as model parameters.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"292 ","pages":"Article 107880"},"PeriodicalIF":2.1,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145827798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.jenvrad.2025.107882
Egor I. Kaygorodov , Petr S. Miklyaev , Tatiana B. Petrova
Radon in buildings is the second most significant risk factor for lung cancer after smoking. Indoor radon concentrations are largely controlled by so-called geogenic radon, which forms in soils and rocks containing radium-226. Mapping the geogenic radon hazard is an urgent task that makes it possible to make managerial decisions in the field of radon standardization. In particular, mapping the geogenic radon hazard makes it possible to identify radon priority areas, which is a requirement of EURATOM BSS. There are different ways to mapping the geogenic radon hazard, and they all have their advantages and limitations.
In this paper, a method for assessing and mapping Diffusion Radon Potential is proposed. This is a new approach to assessing and city-scale mapping geogenic radon hazard of the territories based on the analysis of data on radium concentration and radon diffusion length in shallow soils. An original method for estimating the diffusion coefficient is proposed. It has been shown that in many cases radon transport in soils can be described by a diffusion transport model with a diffusion length from 0.9 m in weakly permeable clays to 2.4 m in well-understood dry sediments. An example of mapping the diffusive radon potential is given using the example of Pyatigorsk and Moscow.
{"title":"A new approach to assessing and mapping geogenic radon hazard","authors":"Egor I. Kaygorodov , Petr S. Miklyaev , Tatiana B. Petrova","doi":"10.1016/j.jenvrad.2025.107882","DOIUrl":"10.1016/j.jenvrad.2025.107882","url":null,"abstract":"<div><div>Radon in buildings is the second most significant risk factor for lung cancer after smoking. Indoor radon concentrations are largely controlled by so-called geogenic radon, which forms in soils and rocks containing radium-226. Mapping the geogenic radon hazard is an urgent task that makes it possible to make managerial decisions in the field of radon standardization. In particular, mapping the geogenic radon hazard makes it possible to identify radon priority areas, which is a requirement of EURATOM BSS. There are different ways to mapping the geogenic radon hazard, and they all have their advantages and limitations.</div><div>In this paper, a method for assessing and mapping Diffusion Radon Potential is proposed. This is a new approach to assessing and city-scale mapping geogenic radon hazard of the territories based on the analysis of data on radium concentration and radon diffusion length in shallow soils. An original method for estimating the diffusion coefficient is proposed. It has been shown that in many cases radon transport in soils can be described by a diffusion transport model with a diffusion length from 0.9 m in weakly permeable clays to 2.4 m in well-understood dry sediments. An example of mapping the diffusive radon potential is given using the example of Pyatigorsk and Moscow.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"292 ","pages":"Article 107882"},"PeriodicalIF":2.1,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145819321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.jenvrad.2025.107881
Carlos Pinto Fracalossi , Peter Christian Hackspacher , Daniel Marcos Bonotto
This paper describes a novel database for the dissolved uranium concentration and 234U/238U activity ratio (AR) in groundwater samples (16), with a focus on those occurring in the Itararé Group in São Paulo State, Brazil. Such a geological unit takes a major role in the multilayered Tubarão Aquifer System (TAS), which has been extensively exploited, primarily due to water use for industrial purposes, agriculture, and human consumption, which has resulted in a drastic lowering of the groundwater static level. As a consequence, efforts have been made by the use of different approaches to understand the processes related to the groundwater flow after infiltration in the recharge area, inclusive by the use of the natural U-isotopes 238U and 234U as reported in this paper. Therefore, hydrogeochemical diagrams utilizing both parameters (dissolved U concentration and AR) were constructed from data obtained by alpha spectrometry, aiming to find trends associated with the groundwater flow direction, as well as with processes involving the mixture of different water sources.
{"title":"238U and 234U relationships in groundwater of Itararé Group, São Paulo State, Brazil","authors":"Carlos Pinto Fracalossi , Peter Christian Hackspacher , Daniel Marcos Bonotto","doi":"10.1016/j.jenvrad.2025.107881","DOIUrl":"10.1016/j.jenvrad.2025.107881","url":null,"abstract":"<div><div>This paper describes a novel database for the dissolved uranium concentration and <sup>234</sup>U/<sup>238</sup>U activity ratio (AR) in groundwater samples (16), with a focus on those occurring in the Itararé Group in São Paulo State, Brazil. Such a geological unit takes a major role in the multilayered Tubarão Aquifer System (TAS), which has been extensively exploited, primarily due to water use for industrial purposes, agriculture, and human consumption, which has resulted in a drastic lowering of the groundwater static level. As a consequence, efforts have been made by the use of different approaches to understand the processes related to the groundwater flow after infiltration in the recharge area, inclusive by the use of the natural U-isotopes <sup>238</sup>U and <sup>234</sup>U as reported in this paper. Therefore, hydrogeochemical diagrams utilizing both parameters (dissolved U concentration and AR) were constructed from data obtained by alpha spectrometry, aiming to find trends associated with the groundwater flow direction, as well as with processes involving the mixture of different water sources.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"292 ","pages":"Article 107881"},"PeriodicalIF":2.1,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1016/j.jenvrad.2025.107875
Sofie Liljegren , J. Ole Ross , Sofia Brander
Between late November and early December 2022, large airborne activity concentrations of radioxenon were detected by multiple stations in the CTBT International Monitoring System (IMS) and the Swedish radioxenon array, which consisted of four operational radioxenon measurement units at the time. Over 100 samples containing were recorded during this period, with Xe found concurrently in about a dozen samples. The consistent Xe to activity ratio, and investigations with backward atmospheric transport models (ATM), suggests a sustained release of radioxenon from a single source for about two weeks. A grid of forward ATMs was computed, and model results were matched with observations to identify potential source regions and estimate the source term. We compare locating power of the sparse, globally distributed IMS network with the compact, local Swedish radioxenon array. In this specific case, the use of the array data both significantly improved the source localization area, and helped exclude local sources, when compared to exclusively using IMS observations. Additionally the Xe to activity ratio was investigated for source characterization, and was found to be consistent with the start of a nuclear reactor cycle.
{"title":"Origin of an elevated radioxenon episode: A comparative study between the Swedish radioxenon array and the CTBT International Monitoring System","authors":"Sofie Liljegren , J. Ole Ross , Sofia Brander","doi":"10.1016/j.jenvrad.2025.107875","DOIUrl":"10.1016/j.jenvrad.2025.107875","url":null,"abstract":"<div><div>Between late November and early December 2022, large airborne activity concentrations of radioxenon were detected by multiple stations in the CTBT International Monitoring System (IMS) and the Swedish radioxenon array, which consisted of four operational radioxenon measurement units at the time. Over 100 samples containing <span><math><mrow><msup><mrow></mrow><mrow><mn>133</mn></mrow></msup><mtext>Xe</mtext></mrow></math></span> were recorded during this period, with <span><math><msup><mrow></mrow><mrow><mn>133</mn><mtext>m</mtext></mrow></msup></math></span>Xe found concurrently in about a dozen samples. The consistent <span><math><msup><mrow></mrow><mrow><mn>133</mn><mtext>m</mtext></mrow></msup></math></span>Xe to <span><math><mrow><msup><mrow></mrow><mrow><mn>133</mn></mrow></msup><mtext>Xe</mtext></mrow></math></span> activity ratio, and investigations with backward atmospheric transport models (ATM), suggests a sustained release of radioxenon from a single source for about two weeks. A grid of forward ATMs was computed, and model results were matched with observations to identify potential source regions and estimate the source term. We compare locating power of the sparse, globally distributed IMS network with the compact, local Swedish radioxenon array. In this specific case, the use of the array data both significantly improved the source localization area, and helped exclude local sources, when compared to exclusively using IMS observations. Additionally the <span><math><msup><mrow></mrow><mrow><mn>133</mn><mtext>m</mtext></mrow></msup></math></span>Xe to <span><math><mrow><msup><mrow></mrow><mrow><mn>133</mn></mrow></msup><mtext>Xe</mtext></mrow></math></span> activity ratio was investigated for source characterization, and was found to be consistent with the start of a nuclear reactor cycle.</div></div>","PeriodicalId":15667,"journal":{"name":"Journal of environmental radioactivity","volume":"292 ","pages":"Article 107875"},"PeriodicalIF":2.1,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145781247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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