Uptake Of Radionuclides Research Articles

Unfolding the interaction of radioactive Cs and Sr with polyethylene-derived microplastics in marine environment

To unveil the interaction of radioactive Cs and Sr with polyethylene-derived microplastics in the marine environment, a mesocosm study was conducted in a stepwise manner by investigating the uptake capability of microplastics at three different stages: pristine, radiation-exposed, and marine-exposed microplastics. The study demonstrates that the physio-chemical properties of microplastics undergo significant alterations upon exposure to the environment, leading to the emergence of biofilm formation upon marine exposure, while radiation exposure induces surface roughness and cracks. Biofilm growth enhances the uptake of radionuclides by microplastics. However, the growth of biofilms increases the density of microplastics through aggregation, leading to a buoyancy transition from positive to negative buoyancy. Various interaction mechanisms, such as electrostatic, ion–dipole, and physical diffusion interactions, were identified as important mechanisms playing key roles in radionuclide binding to polyethylene-derived microplastics. Despite the significantly lower apparent distribution coefficients observed for radio Cs (in the range of 7.3–23.6 L/kg) and Sr (in the range of 4.3–8.06 L/kg) in the marine system, typically 2–3 orders of magnitude lower than those on marine suspended sediment, this study offers compelling evidence that microplastics in marine environments are capable of sequestering radio Cs and Sr. Consequently, microplastics can potentially accumulate these radionuclides, highlighting their role as potential reservoirs as well as vectors of radionuclides in marine environments.

Field-based soil-plant uptake measurements of natural radionuclides for key vegetables and ghaf leaves in Abu Dhabi

With the thriving fossil fuel and nuclear based industries in the nation, radioecology has become necessary for the radiation safety and emergency-preparedness for the United Arab Emirates (UAE). Environmental radiation transport modelling in the UAE and the Arabian Peninsula are severely limited, as we discuss in this paper, due to lack of experiments specific to arid desert climates. To fill the missing gaps in the baseline arid region radioecological database, especially for the soil-plant uptake studies, rigorous field works have been conducted for the first time on the soil and plant in the farms and open fields of the UAE. We present Abu Dhabi based measurements of activity concentrations of radionuclides of natural origins, in soils, key vegetables (cucumber, tomato, and bell pepper), and leaves of ghaf - a prominent native tree. The empirical data are utilized to get the first published estimates of UAE-specific plant-soil concentration ratios (CR), measuring root uptake of radionuclides in nonleafy vegetables and native trees. Such systematic studies are very rare for arid sandy soils. For the 27 samples analyzed, the activity concentrations' (unit Bq kg−1) ranges are: 169–1746 for 40K, 12–19.5 for 226Ra, and 2.7–23.1 for 228Ra. Likewise, wide variability is seen in the averages of concentration ratios also, ranging in 1.05–4.94 for 40K, 0.14–1.82 for 226Ra, and 0.53–2.78 for 228Ra. A net bioaccumulation (concentration ratio >1) of some of these natural radionuclides is found in many samples, but no significant doses or hazard indices are found due to these three radionuclides in the UAE's soils and vegetations. The paper discusses the careful work through tens of field sampling exercises, well controlled sample processing, high resolution gamma spectrometry, and treatment of data from gamma counting rates to accumulated dose rate estimations.

Levels of naturally occurring radioisotopes in local and imported bottled drinking water available in Québec City, Canada

Consumption of local and imported bottled water in Canada has greatly increased during the past three decades. While the presence of natural radioactivity is often overlooked when dealing with the water quality of these bottled products, it could contribute substantially to the uptake of radionuclides especially when sourced from regions with higher radioactivity levels compared to where it is consumed. In this study, the activity of several naturally occurring radionuclides (i.e., 210Po, 226,228Ra, 230,232Th, 234,235,238U) were measured in bottled water available in Québec, Canada after sample pretreatment and analysis by either radiometric or mass spectrometry approaches. 230,232Th and 228Ra concentrations were below minimum detectable activity levels in all samples tested. Analytical results for 234U, 235U, 238U, and 226Ra showed concentrations that ranged from 0.38 to 115 mBq/L, (2.2–313) x 10−2 mBq/L, 0.48–58.4 mBq/L, and 1.1–550 mBq/L, respectively. 210Po was detected in only 5 samples and its activity ranged from 2 to 26 mBq/L. To determine variability in activity within brands, the same brands of bottled water were purchased during two consecutive years and analyzed. The possible radiological impact of the consumption of these types of water was assessed based on different drinking habit scenarios. Some of the imported water brands showed higher activity concentrations than local sources or tap water, suggesting that individuals drinking predominantly imported bottled water would receive a higher radiation dose than those who drink mainly local water.

Geochemical Distribution and Environmental Risks of Radionuclides in Soils and Sediments Runoff of a Uranium Mining Area in South China.

Uranium mining activities have contributed to the distribution and uptake of radionuclides, which have increased the active concentrations of natural radionuclides in environmental media, causing elevated human health risks. The present study aims to assess the spatial distribution characteristics of natural radionuclides in the surface soils and river sediments of the typical granite uranium mining area in South China, as well as investigate the geochemical features of natural radionuclides in the soil and sediments to understand their migration processes. The activity concentrations for 238U, 226Ra, 232Th, and 40K ranged from 17-3925 Bq/kg, 50-1180 Bq/kg, 29-459 Bq/kg, and 240-1890 Bq/kg, respectively. The open-pit mining areas and tailings pond locations exhibited the highest concentrations of activity for all these radionuclides. This distribution points to an elevated potential health risk due to radiological exposure in these specific areas. Additionally, the values of radium equivalent activity (Raeq) and annual gonadal dose equivalent (AGDE) in those areas were higher than the limits recommended by ICRP (2021). 238U and 226Ra have a significant correlation (0.724), and the cluster analysis was showing a statistically meaningful cluster below 5 indicated that they have similar behavior during parent rock weathering and watershed erosion, and the distribution of 232Th and 40K were influenced by the addition of rock types. The activity ratios of 226Ra/238U, 226Ra/232Th, 238U/40K, and 226Ra/40K variation indicated that 40K more mobile than 226Ra and 238U, U(VI) was reduced to U(IV) by organic matter in the downstream area and re-entered into the sediment during the sediment surface runoff in the small watershed of the uranium ore open-pit mining area. Therefore, it is necessary to further seal up and repair the tailings landfill area.

Measurement of transfer factors from soil-to-plant/food crop of Naturally Occurring Radionuclide Materials (NORMs) in Nigeria: a review

One of the most crucial factors in the environmental safety assessment for the local and global communities, situated either in normal background areas or around nuclear facilities, is the uptake of radionuclides from soil by plants, which is typically stated as soil-to-plant Transfer Factor (TF) or Transfer Coefficient (TC). Such a metric, which can be defined as the ratio of radioactivity unit per dry crop mass to that of unit per dry soil mass, is necessary for environmental transfer models, which help to estimate the radionuclide concentrations in agricultural crops and calculate the dose exposure to people. In this article, a number of research studies conducted by scholars in Nigeria, published in both national and international journals, were compiled and reviewed for the purpose of providing an integrated and synthesized overview of the current state of knowledge on NORMs’ transfer factors in Nigeria. The activity concentrations of 40K, 226Ra, 228Ra, 232Th and 238U were measured by different research groups using gamma ray spectrometry coupled with either NaI(Tl) or HPGe detector. The activity concentrations of natural radioactivity in soils samples were generally higher than the values recorded in plant and food crop samples in almost all the research studies considered in the review. About 79% of the values of soil-to-plant transfer factor of 40K in all the studies under review were greater than the recommended value, while the values of transfer factors reported for 232Th and 238U were all greater than the recommended values.

Radiological and economic efficiency of the cesium-137 sorbent

On the territory of radioactive contamination, in the system of measures aimed at reducing the uptake of radionuclides by livestock products, a large place is occupied by the methods of introducing cesium-binding sorbents into the diets. However, the disadvantage of their use is the lack of the local production in Belarus.The article discusses the radiological and economic efficiency of the caesium-137 sorbent of the Belarusian origin. It has been established that the Belarusian-made enterosorbent in the diet of rabbits at a dose of 2 g/head, 4 g/head and in the diet of bulls at a dose 40 g/head is 1,4, 2,6 and 1,15 times respectively more effective than pure ferrocine. Starting from the 5th to the 20th day of using the carbon sorbent, there is a decrease in the content of cesium-137 in the milk of cows from 1,7 to 4,5 times.The cost per 1 thousand Bq of the difference in the accumulation of cesium-137 in rabbit meat in case of the Belarusian sorbent at a dose of 2 g/head by 7,6 times lower in comparison with ferrocine, at a dose of 4 g/head by 4,0 times, in beef by 5,5 times, in milk by 5,2 times lower.

Gamma spectroscopy study of soil-plant transfer factor characteristics of 40K, 232Th and 226Ra in some crops cultivated in southwestern region of Nigeria

Soil-plant transfer factor (TF) is one of the vital variables employed in assessing plants uptake of radionuclides and their transfer to food chain for predictive ingestion dose and risk evaluation. To further this goal, the TF characteristics of natural 40K, 232Th and 226Ra were thus investigated in some crops (yam, cassava, rice, maize, groundnut, cowpea, okra, pumpkin leaf, banana and pawpaw) cultivated in southwestern part of Nigeria using HPGe gamma spectroscopy. The obtained results of activity concentration (AC) of the radionuclides across all the cultivated soil samples indicated average values that are less than the global average, whereas in the crops, average values of 226Ra and 232Th, were higher than reference values for different crops group. The overall range of the calculated TF of 40K, 232Th and 226Ra across all the crops was 0.05 (in maize and cowpea) to 15.01 (in banana), 0.01 (in pumpkin leaf and groundnut) to 19.80 (in pawpaw), and 0.04 (in cassava) to 21.30 (in cowpea), respectively. Overall arithmetic mean and geometric mean were estimated as 2.66 and 1.60, 1.11 and 0.43, and 1.10 and 0.54 for 40K, 232Th and 226Ra, respectively. TFs mostly correlated negatively with soil radionuclides, while positive correlation was mostly noticeable in the case of crop. Log normal transform of the TFs data indicated a near normal distribution as against the calculated data. The derived results of this study is here presented as a baseline data suggested for possible radiological risk assessment of food chain of the local population.

Comparison of methods for the radiological impact assessment of aquatic releases to the waters in the low countries

Accurate assessment of the radiological impact of liquid discharges on the marine environment is challenging despite all developments in recent years. The lack of consensus on this type of assessment manifests itself even stronger when transborder issues are expected, such as in the Low Countries. Belgium and the Netherlands operate nuclear power plants with discharges in the shared estuary of the Western Scheldt, therefore if there are safety concerns, information on both sides of the border must be coherent. This work provides a comparison of two computational methods used for assessment of aquatic releases in the Western Scheldt estuary and the adjacent North Sea.The work demonstrates a fair degree of consistency in modelling the uptake and fate of key anthropogenic radionuclides. Nevertheless, there are also considerable differences found in sediment and sea species with concentrations ranging by over two orders of magnitude in some cases. These explainable differences are methodological in nature, occurring in codes that underwent extensive validation during development. Therefore, the outcomes of this work clearly demonstrate the need to produce explicit guidance that is specifically tailored to the (inter)national water system of concern. This should not be limited to releases from nuclear power plants, but also include other nuclear applications. For all these reasons, more intensive collaboration and model harmonisation across borders is essential, signalling the direction for future investigations.

Development of metakaolin-based geopolymer for selenium oxyanions uptake through in-situ ettringite formation

Studies have demonstrated the remarkable capacity of metakaolin-based geopolymers for the uptake of cationic radionuclides, such as Cs+ and Sr2+. However, the lack of uptake ability towards anionic radionuclides represents a potential avenue for improvement in utilising this material for nuclear waste disposal applications. Additionally, the prevalence of ettringite as an anion exchange agent formed in alkaline environments, such as cement hydration, is widely acknowledged in the field. However, no previous studies have been conducted to explore the utilisation of the advantageous qualities of both metakaolin-based geopolymer and ettringite in developing a comprehensive incorporation process for both cationic and anionic radionuclides. In this study, compositions and sets of preparation conditions were proposed to modify metakaolin-based geopolymer, resulting in the in-situ formation of ettringite, with the aim of enhancing its uptake capabilities for selenium oxyanions. The uptake behaviour and mechanism of ettringite, and geopolymer with in-situ ettringite, were proposed through co-precipitation experiments, binding and structural analysis. The results reveal that the ettringite can uptake SeO32- and SeO42- through co-precipitation; however, its effectiveness is limited to SeO32- in the uptake process, where the mechanism is contingent on the concentration of Se oxyanions present. On the other hand, modified geopolymer with in-situ ettringite retained its capacity to uptake cationic radionuclides such as Cs+ and Sr2+ while evolving to exhibit an ability to uptake SeO32-. Thermodynamic modelling was carried out according to the ion exchange mechanism, which effectively predicts the uptake of SeO32- at low concentrations. The proposed composition and preparation conditions hold the potential for developing an effective incorporation process for cationic and anionic radionuclides. The outcomes of this research enhance the understanding of the uptake behaviour of Se oxyanions by ettringite and provide insight into the potential of metakaolin-based geopolymers to immobilise anions.

Evaluation of the Effect of Chelating Arms and Carrier Agents on t he Radiotoxicity of TAT Agents.

Targeted Alpha Therapy (TAT) is considered an evolving therapeutic option for cancer cells, in which a carrier molecule labeling with an α-emitter radionuclide make the bond with a specific functional or molecular target. α-particles with high Linear Energy Transfer (LET) own an increased Relative Biological Effectiveness (RBE) over common β-emitting radionuclides. Normal tissue toxicity due to non-specific uptake of mother and daughter α-emitter radionuclides seems to be the main conflict in clinical applications. The present survey reviews the available preclinical and clinical studies investigating healthy tissue toxicity of the applicable α -emitters and particular strategies proposed for optimizing targeted alpha therapy success in cancer patients.

Uptake of Radionuclides by Bryophytes in the Chornobyl Exclusion Zone

The "Chernobyl nuclear disaster" released huge amounts of radionuclides, which are still detectable in plants and sediments today. Bryophytes (mosses) are primitive land plants lacking roots and protective cuticles and therefore readily accumulate multiple contaminants, including metals and radionuclides. This study quantifies 137Cs and 241Am in moss samples from the cooling pond of the power plant, the surrounding woodland and the city of Prypiat. Activity concentrations of up to 297 Bq/g (137Cs) and 0.43 Bq/g (241Am) were found. 137Cs contents were significantly higher at the cooling pond, where 241Am was not detectable. Distance to the damaged reactor, amount of original fallout, presence of vascular tissue in the stem or taxonomy were of little importance. Mosses seem to absorb radionuclides rather indiscriminately, if available. More than 30 years after the disaster, 137Cs was washed out from the very top layer of the soil, where it is no more accessible for rootless mosses but possibly for higher plants. On the other hand, 137Cs still remains solved and accessible in the cooling pond. However, 241Am remained adsorbed to the topsoil, thus accessible to terrestrial mosses, but precipitated in the sapropel of the cooling pond.

Detection of Radiolabeled Inflammatory Cell Macrophage Subpopulations in Chronic Respiratory Diseases: Results from Preliminary Analyses.

Chronic respiratory diseases (CRDs) like asthma and chronic obstructive pulmonary disease (COPD) are the leading causes of morbidity and mortality worldwide. Alveolar macrophages (AM) are immune cells that exist in different polarization states/phenotypes and have been shown to play a critical role during an inflammatory process. In this paper, differently polarized mouse bone marrow-derived macrophages (BMDM (M1-proinflammatory or M2-immunomodulator)) were radiolabeled with either 99mTc-D,L-hexamethylene-propyleneamine oxime (99mTc-HMPAO), 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG), or 67Ga-citrate. Biocompatibility and in vivo biodistribution of radionuclide-labeled macrophages after intravenous injection were evaluated. Radioactivity measurements were performed using Packard Cobra Quantum 5002 Gamma Counter. Both M1 and M2 macrophages showed a higher uptake for 18F-FDG and 99mTc-HMPAO, than 67Ga-citrate. M2 macrophages showed a higher uptake of radionuclides than M1 macrophages. The used radionuclides were biocompatible for both M1 and M2 macrophages. At 2-hour postinjection, 18F-FDG-labeled M1 and M2 macrophages were found significantly higher in the lung of inflammatory animals (12.54 ± 1.58% and 14.13 ± 1.03%, respectively) than in control mice. Labeling macrophages with either 18F-FDG or 99mTc-HMPAO did not affect their biodistribution. The results from these initial experiments indicate that radionuclide-labeled macrophages may allow a higher sensitivity detection in nuclear imaging techniques such as PET and SPECT. Further confirmatory studies are needed to noninvasively image radiolabeled BMDM to understand their role in the inflammatory processes inherent to CRDs.

Updated soil to fruit concentration ratios for radiocaesium compiled under the IAEA MODARIA II Programme

Under the International Atomic Energy Agency (IAEA) Modelling and Data for Radiological Impact Assessments (MODARIA II) Programme, Working Group 4 activities included collating radionuclide transfer data from Japan following the Fukushima Daiichi Nuclear Power Plant accident and separately collating concentration ratio (CR) data for root uptake of radionuclides by crops grown in tropical and arid climates. In this paper, the newly compiled radiocaesium CR data for fruit from Japan, tropical and arid climates have been combined with the data originally compiled for the IAEA Technical Reports Series No. 472 (TRS 472) and additional data identified from the literature to produce an enhanced MODARIA II dataset of fruit radiocaesium CR values. Statistical analysis of the MODARIA II dataset by climate class (based on the Köppen–Geiger climate classification) indicated that the CR values for tropical climates were significantly higher (p < 0.05) than those for arid, temperate and cold climates. Statistical analysis of the MODARIA II dataset by soil group (based on soil texture) indicated that the CR values for coral sand soil (tropical climates only) and organic soil (temperate climates only) were significantly higher (p < 0.05) than those for the clay, loam and sand soil groups. Statistical analysis of the MODARIA II dataset by plant group (based on plant morphology) indicated that the CR values for non-woody trees (tropical climate bias) were significantly higher (p < 0.05) than those for herbaceous plants, shrubs and woody trees. Comparison of the MODARIA II dataset with original TRS 472 values showed only small changes in the fruit radiocaesium CR values for herbaceous plants and shrubs in temperate climates. There was a decrease in the CR values for woody trees in temperate climate across all soil groups. There was also a decrease in the CR values for tropical climates for all comparable soil groups.

Solubility of Ca(II), Ni(II), Nd(III) and Pu(IV) in the presence of proxy ligands for the degradation of polyacrylonitrile in cementitious systems.

The solubility of Ca(OH)2(cr), β-Ni(OH)2(cr), Nd(OH)3(s) and PuO2(ncr, hyd) was investigated in cement porewater solutions containing glutarate (GTA), α-hydroxyisobutarate (HIBA) and 3-hydroxybutarate (HBA). These ligands were proposed as probable degradation products of UP2W, a polyacrylonitrile-based filter aid used in nuclear power plants. Results obtained in this work are compared with reported solubility data in the presence of iso-saccharinic acid (ISA), a polyhydroxocarboxylic acid resulting from cellulose degradation. None of the investigated proxy ligands shows any significant impact on the solubility of Ca(II), Nd(III) or Pu(IV) in cement porewater solutions. Although the formation of binary complexes M-L (M = Ca(II), Nd(III), An(IV); L = GTA, HIBA, HBA) under acidic conditions is described in the literature, these organic ligands cannot outcompete hydrolysis under hyperalkaline conditions. GTA, HIBA and HBA induce a slight increase in the solubility of β-Ni(OH)2(cr) at [L]tot = 0.1 M. This observation supports the formation of stable Ni(II)-GTA, -HIBA and -HBA complexes in hyperalkaline conditions, although the exact stoichiometry of these complexes remains unknown. The comparison of these results with solubility data in the presence of ISA confirms the stronger complexation properties of the latter ligand. Even though HIBA and HBA are carboxylic acids containing one alcohol group, this comparison shows that additional alcohol groups are required to efficiently chelate the metal ion and outcompete hydrolysis. This conclusion is supported by DFT calculations on the Pu(IV)-OH-L systems (L = GTA, HIBA and HBA), which indicate that the complexation with the proxy ligands takes places through the carboxylate group. XRD of selected solid phases after equilibration with proxy ligands at [L]tot = 0.1 M confirms that Ca(II), Ni(II), Nd(III) and Pu(IV) starting solid materials remained mostly unaltered in the course of the experiments. However, the presence of new XRD features suggests the possible formation of secondary phases. These results allow assessment of the effect of the proposed proxy ligands on the solubility of key radionuclides and metal ions in cementitious systems relevant for low and intermediate level waste, and feed into on-going sorption studies evaluating the impact of UP2W degradation products on the uptake of radionuclides by cement.

Accumulation of radio-iron and plutonium, alone and in combination, in Pseudomonas putida grown in liquid cultures

The impact of low doses of ionising radiation on biological and environmental systems have been historically difficult to study. Modern biological tools have provided new methods for studying these mechanisms but applying these tools to a dose–response relationship may require refinement of dosimetric techniques that incorporate a detailed understand of radionuclide accumulation in biological cells, particularly when assessing the impact of low doses of ionising radiation. In this work Pseudomonas putida (KT2440) grown in liquid culture was exposed to low dose rates (10–20 mGy d−1) of 239Pu and 55Fe, both alone and in combination, for a period of 20 days, and the accumulation of 239Pu and 55Fe in cell pellets was analysed via liquid scintillation counting. The study also considered of cells grown with 239Pu and stable Fe (primarily 56Fe). In addition to the analysis of cell pellet and media samples, this work includes analysis of the radiological content of ribonucleic acid extraction samples to examine uptake of radionuclides. Results indicate that 239Pu inhibited the uptake of 55Fe, and that the presence of stable and radioactive isotopes of Fe in cultures may promote pathways for Fe accumulation that are used by 239Pu. The work herein provides foundational insight into future dosimetric models for our work with environmental bacteria.

The application of 99Tcm-DTPA orbital SPECT/CT in staging evaluation of thyroid associated ophthalmopathy

Objective: To explore the application value of 99Tcm-diethylenetriaminepentaacetic acid (DTPA) orbital single photon emission computed tomography/computed tomography (SPECT/CT) in staging evaluation of thyroid associated ophthalmopathy (TAO). Methods: A case-control study. A total of 40 patients with binocular TAO were recruited from May 2019 to December 2019 in the Second Hospital of Dalian Medical University. According to the clinical activity score (CAS) standard, 40 TAO patients were divided into the active group (15 cases) and the inactive group (25 cases), and 10 healthy volunteers were recruited as the control group. All subjects underwent 99Tcm-DTPA orbital SPECT/CT examination, and each subject's CAS, reading results and maximum standardized uptake value (SUVmax) were recorded. The Kruskal-Walis H test was used for the CAS comparison among the three groups. The analysis of variance was used for the SUVmax comparison among the three groups. The comparison between CAS and SUVmax before and after treatment was performed by paired samples Wilcoxon signed rank test and paired-sample t test, and Spearman correlation analysis was performed between SUVmax and CAS. The Kappa test was used to check the consistency between the reading result and CAS's judgment of TAO activity. The receiver operating characteristic curve was used to analyze the diagnostic value of the reading results and SUVmax for TAO. Results: The age difference among the three groups was not statistically significant, and the gender difference was not statistically significant (all P>0.05). The difference in CAS among the three groups was statistically significant (H=39.894; P<0.01). Patients with active TAO showed abnormal concentration and enhancement of nuclides in the orbital tissue, and the uptake of radionuclides was significantly increased, while patients with inactive TAO had a slight increase, and healthy volunteers had no significant or only mild uptake. The SUVmax of the active group (2.24±0.47) was highest, and that of the inactive group (1.57±0.43) was higher than the healthy control group (0.67±0.22). After pairwise comparison, there were statistical differences between groups (all P<0.05). According to Spearman correlation analysis, the SUVmax of all TAO patients was linearly, positively correlated with their CAS (r=0.753; P<0.05). In assessing the clinical activity of TAO, the reading results were consistent with CAS (Kappa value=0.737; P<0.05). Taking the reading results as the standard, the area under the receiver operating characteristic curve (AUC) of SUVmax was 0.992, and the threshold of SUVmax to distinguish between active and inactive periods was 1.850, with a sensitivity of 86.70% and a specificity of 76.00%. Taking CAS results as the standard, the AUC of SUVmax was 0.853, and the threshold of SUVmax to distinguish between active and inactive periods was 1.850, with a sensitivity of 100.00% and a specificity of 87.50%. Five patients had inconsistent SUVmax and CAS. The CAS was ≥3, but the orbits did not show any inflammatory lesions in two of them; the CAS was<3, but the orbits showed inflammatory lesions in three of them. Thirteen active TAO patients with 99Tcm-DTPA orbital SPECT/CT showing significant accumulation of nuclides were given hormone shock therapy 12 times. After treatment, the CAS 2.00 (2.00) was lower than the pre-treatment 3.00 (1.50) score, and the difference was statistically significant (Z=-3.100, P<0.01). The SUVmax after treatment (1.60±0.20) was lower than the pre-treatment value (2.17±0.34), and the difference was statistically significant (t=10.197, P<0.01). Conclusion: 99Tcm-DTPA orbital SPECT/CT can relatively accurately determine the state of orbital inflammation in patients with TAO, and can be used as a useful supplement to evaluate the clinical activity of TAO, helping to guide clinical treatment. (Chin J Ophthalmol, 2021, 57: 830-836).

Imaging of I, Re and Tc plant uptake on the single-cell scale using SIMS and rL-SNMS

In radioecological studies, there is a significant need for understanding the plant uptake of radionuclides on a cellular level. The present work applies mass spectrometry to image the radionuclide distribution within the cellular structures of plants at varying concentrations. In a first step, plants of Daucus carota and Pisum sativum labelled with iodine and rhenium were examined, at concentrations in the range of 10 mM. Cross sections of several plant parts were imaged by secondary ion mass spectrometry (SIMS) after cryogenation in order to preserve cell structure. In a second step, the distribution of 99Tc in the two plant species was determined. For radiological reasons, a concentration three orders of magnitude lower was used, rendering measurements with SIMS impossible. Therefore, resonant laser secondary neutral mass spectrometry (rL-SNMS) was used for the first time to image 99Tc with suppression of molecular isobaric interferences. The measurement of only about 1010 atoms of 99Tc atoms is demonstrated and the distribution of 99Tc within a single epidermal cell is imaged.

Soil - Plant transfer of radionuclides in arid environments

The use of nuclear power as an environmentally friendly, and sustainable means for energy production is heavily under discussion. Despite this recently several countries with a predominantly arid climate have sought to develop or deploy nuclear energy production systems. However, there is little information on how radionuclides behave in different, especially arid, climates. Members of the IUR task group for arid environment and of the IAEA MODARIA II working group 4 contributed to such a supplement to the International Atomic Energy Agency (IAEA) Technical Report Series No. 472 (IAEA, 2010) Handbook of Parameter Values for the Prediction of Radionuclides Transfer in Terrestrial and Freshwater Environments under the IAEA Modelling and Data for Radiological Impact Assessments (MODARIA II) programme (2016–2019) to close this knowledge gap. Data on concentration ratios for plant and soil (CR) in arid environments following the Köppen-Geiger classification of climates were collated, summarised and quality assured. The combination of this data with transfer parameter data for root uptake of radionuclides by food crops in tropical environments (this issue) aimed to compare all data with those in TRS 472 recommended for use in dose assessment models. Therefore, a databank has been started based on an intensive literature research on published concentration ratio (CR) data in selected arid environments. After quality check data have been formatted to comply with TRS 472 and with the tropical data base criteria. Due to the scarcity of published information and the high uncertainty of the estimated mean values for individual plant and soil groups in arid environments no statistically relevant conclusions could be drawn, although some differences were notable. Nevertheless, despite its limitations and high uncertainties, this work presents the first reported comprehensive data collation on CR soil-plant values in arid environments.

Stable isotope analysis in environmental impact assessment of radioactivity releases from nuclear power plants

The potential use of stable fission products from the decay of radioactive contaminants in recreating the impact assessment of radioactivity releases from nuclear power stations is examined. With the advances in mass spectrometry, Minimum Detectable Limits (MDLs) comparable to radioactive measurements have been achieved in the case of stable isotopes as well. The applications of stable fission products in safeguards and environmental surveillance by the author are mentioned. The limited application of stable fission products in the analysis of Fukushima environmental samples is reviewed. The article examines the possible candidates for such analysis and points out the enormous possibilities. This is a neglected field in environmental impact assessment till now and calls for standardizing measurement procedures and analysis methodologies. The stable fission product signatures can also be used to study the uptake and transport of radionuclides in the environment.

Radionuclides and stable elements in vegetation in Australian arid environments: Concentration ratios and seasonal variation

Data on the uptake of elements and radionuclides by flora from soils in arid environments are underrepresented in international databases, especially when comparing across seasons. This study improved the understanding on the uptake of natural uranium-series radionuclides, as well as more than 30 elements, in a range of Australian native flora species that are internationally representative of an arid/semi-arid zone (e.g. Acacia, Astrebla, Atriplex, and Dodonea). Results indicate that the soil-to-plant uptake ratios were generally higher when compared with international data for grasses and shrubs from more temperate environments. The majority of the elemental concentrations in grasses were higher in winter than in summer and the opposite trend was found in shrubs, which suggests that the season of collection potentially introduces variability in the reported concentration ratios. The data also suggest that grasses, being dominant and widespread species in arid zones, may be effective as a reference organism to ensure comparative assessment across sites of interest. The results of this study will improve the confidence of environmental assessments in arid zones.