| 1. |
- Cwanek, Anna, et al.
(författare)
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The study of Canadian Arctic freshwater system toward radioactive contamination - status in 1999
- 2021
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Ingår i: Journal of Environmental Radioactivity. - : ELSEVIER SCI LTD. - 0265-931X .- 1879-1700. ; 226
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Tidskriftsartikel (refereegranskat)abstract
- This work provides a novel data set on accumulations of both anthropogenic (Cs-137, Pu-238, Pu239+240, Am-241) and natural (Pb-210, Ra-226, Th-232) radionuclides and an element (K). Sampling of soils and lake sediments was accomplished in 1999 during Tundra Northwest (TNW-99) international expedition to a remote region of the Canadian Arctic. The sediment ages and sedimentation rates were determined. The obtained results overall indicated a high geographical diversity of contamination levels and trends. Accumulation rates were also differential, and a sediment focusing contribution was distinctly visible. Radioactive pollution was found to be lower relative to temperate counterparts. The activity ratios of anthropogenic radionuclides corresponded to global fallout as a prevailing source in the entire examined area. The post-Chernobyl radiocaesium was observed for the westernmost lake only. The elevated level of Cs-137 and Pu239+240 in the topmost sediment at the northern and eastern Arctic Archipelago was attributed to recent resuspension and subsequent redistribution of radionuclides.
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| 2. |
- De La Torre Luque, Pedro, et al.
(författare)
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Testing machine learning algorithms for the prediction of depositional fluxes of the radionuclides 7Be, 210Pb and 40K
- 2023
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Ingår i: Journal of Environmental Radioactivity. - 0265-931X .- 1879-1700. ; 265
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Tidskriftsartikel (refereegranskat)abstract
- The monthly depositional fluxes of 7Be, 210Pb and 40K were measured at Malaga, (Southern Spain) from 2005 to 2018. In this work, the depositional fluxes of these radionuclides are investigated and their relations with several atmospheric variables have been studied by applying two popular machine learning methods: Random Forest and Neural Network algorithms. We extensively test different configurations of these algorithms and demonstrate their predictive ability for reproducing depositional fluxes. The models derived with Neural Networks achieve slightly better results, in average, although similar, having into account the uncertainties. The mean Pearson-R coefficients, evaluated with a k-fold cross-validation method, are around 0.85 for the three radionuclides using Neural Network models, while they go down to 0.83, 0.79 and 0.8 for 7Be, 210Pb and 40K, respectively, for the Random Forest models. Additionally, applying the Recursive Feature Elimination technique we determine the variables more correlated with the depositional fluxes of these radionuclides, which elucidates the main dependences of their temporal variability.
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| 3. |
- Holmerin, Isak, et al.
(författare)
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Benthic food web structures as an explanation for prolonged ecological half-life of Cs-137 in flatfish species in the Fukushima coastal area
- 2022
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 246
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Tidskriftsartikel (refereegranskat)abstract
- After the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP), Japan, in March 2011, Cs-137 in demersal fish had, between 2011 and 2015, a prolonged ecological half-life when compared to pelagic fish. Using stable isotope mixing models combined with gut content analysis and Cs-137 activity concentrations, this study investigated the hypothesis that an unexplored food web structure could be a contributing factor explaining the ecological half-life of Cs-137 in benthic flatfish. Benthic invertebrates and demersal fish species sampled in 2015 still showed Cs-137 activity concentrations higher than pre-accident. The mixing models of stable N and C isotopes and gut content analysis identified deposit, suspension and filter feeders to be the main flatfish food items in the benthos. There was a significant correlation between Cs-137 activity concentrations in specific flatfish species and benthos, and between Cs-137 activity concentrations in benthos and surface sediment. The results of this study partially explained the Cs-137 activity concentrations found in the analysed demersal fish, suggesting that the benthos can be a continuous source of Cs-137 for the demersal fish during this period of time. Extending monitoring programmes to include invertebrates that are not food species for humans would greatly improve our ability to understand the role of trophic transfer pathways and take appropriate management actions.
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| 4. |
- Insulander Björk, Klara, 1982, et al.
(författare)
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Experimental determination of concentration factors of Mn, Zn and I in the phytoplankton species Phaeodactylum Tricornutum
- 2023
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 261
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic radionuclides released into the environment cause a radiation dose to wildlife and humans which must be quantified, both to assess the effect of normal releases, and to predict the consequences of a larger, unplanned release. To estimate the spread of the radioactive elements, the ecosystem around release points is modelled, and element uptake is usually quantified by concentration factors (CF), which relates the concentration of an element in an organism to the concentration of the same element in a medium under equilibrium conditions. In this work, we experimentally determine some phytoplankton CF that are needed for improved modelling of the marine ecosystems around nuclear facilities and release points. CFs that require better determination have been identified through literature search. Sensitivity studies, using the currently used ecosystem modelling software PREDO, show that for most studied groups, the dose committed by the respective radionuclides is almost proportional to the corresponding phytoplankton CFs. In the present work, CFs are determined through laboratory experiments with cultured phytoplankton and radionuclides of the concerned elements, assessing the element uptake by the phytoplankton through detection of the emitted radiation. The three CF assessed in this work were those for manganese, zinc and iodine in phytoplankton. Conservative estimates of these CF based on the present data are 40 000 L/kg for manganese, 50 000 L/kg for zinc and 180 L/kg for iodine with the phytoplankton masses referring to their dry weight.
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| 5. |
- Rääf, Christopher, et al.
(författare)
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Restoring areas after a radioactive fallout : A multidisciplinary study on decontamination
- 2023
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier. - 0265-931X .- 1879-1700. ; 270
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Tidskriftsartikel (refereegranskat)abstract
- Land remediation is an important part of restoration measures after a radioactive fallout containing long-lived fission products such as 137Cs. In this multidisciplinary study, we focused on three main issues related to remediation of contaminated urban areas. First, we assessed how much decontamination contributes to reducing resident radiation exposure and how much this reduction depends on the timing of implemented measures. Second, we calculated direct and indirect costs of decontamination in an industrialized country such as Sweden. Finally, in a survey study, we considered reactions of Swedish citizens to being given the hypothetical option of moving to a site decontaminated after radioactive fallout and how this predicted response might influence the design of contingency plans. The main findings are that clean-up operations must be done within the first few years after a fallout to contribute significantly to reducing residual dose. If conducted within 1-2 years, large-scale decontamination can, on average, avert 20-200 manSv per km2 residential area and unit ground deposition of 137Cs (1 MBq). The estimated direct costs (in 2020 purchasing power) would amount to 100 million Euro per km2 decontaminated residential area (comparable to Japanese estimates after the Fukushima accident), generating 39,000 m3 of radioactive waste on average, mainly in the form of 137Cs-contaminated topsoil. In our survey study of 2291 Swedish respondents about their willingness to return to decontaminated homes, women, families with resident children, and high-income earners exhibited more skepticism about returning, even if authorities were to deem it safe. The demographic pattern in attitudes was similar to that found among evacuees in the Fukushima prefecture after 2011. We conclude that predefined ranges of measured 137Cs ground deposition can be used as guidance for rescue leaders in the early post-accident phase in long-term planning for affected areas. This planning should include timing and intensity of decontamination measures, duration of evacuation, and risk communication to citizens. Because some citizens expressed both high risk perception and risk aversion, however, timely and dialogic communication is unlikely to limit a shift after the incident to an older and more male-dominated population composition. There is a risk that those who can afford to do so will move away, whereas people whose wealth is locked in property (houses or businesses) will feel stuck. Perceptions of unfairness may fray the social fabric and complicate resettlement, which in some cases may mean inefficient outlay of decontamination costs. We believe that the issue of monetary compensation to affected residents requires priority in future work.
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| 6. |
- Sundell-Bergman, Synnöve, et al.
(författare)
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Response of spring wheat and potato to foliar application of Zn, Mn and EDTA fertilizers on Cs-137 uptake
- 2021
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- The impact of foliar fertilization with zinc (ZnSO4) and manganese (MnSO4 on Cs-137 uptake by spring wheat and potato was studied. The experiments were conducted during 3 years (2014-2016) in a Cs-137-contaminated area, Zhytomyr region of Ukraine. The fertilization was carried out on podzolic loamy sand soil, poor in most of the microelements. Both crops were fertilized at four successive stages of growth. Foliar application of fertilizers caused higher yield of wheat grain/straw and potato tubers yield in 2014-2015 years but had no effect in 2016. Thus, the overall effect of fertilization between 2014 and 2016 was less pronounced and generally insignificant. Application of Zn, Mn and EDTA reduced Cs-137 uptake by wheat grain and potato tubers, when fertilized at earlier stages of growth and development in years 2014 and 2015 by factor 1.5-2.0, while in 2016 the effect was generally statistically insignificant. It is suggested, that reduction of Cs-137 uptake by spring wheat and potato, at least partly, was caused by an effect of radionuclide dilution due to the higher biomass of the plants. A foliar spray of EDTA at earlier stages of plant growth and development may be considered as a potential countermeasure aiming reducing Cs-137 uptake from soil to plants, even if such effect appeared to be conditional.
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| 7. |
- Söderström, Mats
(författare)
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Footprint and height corrections for UAV-borne gamma-ray spectrometry studies
- 2021
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 231
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Tidskriftsartikel (refereegranskat)abstract
- Advancements in the development of gamma-ray spectrometers (GRS) have led to small and lightweight spectrometers that can be used under unmanned aerial vehicles (UAVs). Airborne GRS measurements are used to determine radionuclide concentrations in the ground, among which the natural occurring radionuclides K-40, U-238, and Th-232. For successful applications of these GRS sensors, it is important that absolute values of concentrations can be measured. To extract these absolute radionuclide concentrations, airborne gamma-ray data has to be corrected for measurement height. However, the current analysis models are only valid for the height range of 50-250 m. The purpose of this study is to develop a procedure that correctly predicts the true radionuclide concentration in the ground when measuring in the UAV operating range of 0-40 m. An analytical model is developed to predict the radiation footprint as a function of height. This model is used as a tool to properly determine a source-detector geometry to be used in Monte-Carlo simulations of detector response at various elevations between 0 and 40 m. The analytical model predicts that the smallest achievable footprint at 10 m height lies between 22 and 91 m and between 40 and 140 m at 20 m height. By using Monte-Carlo simulations it is shown that the analytical model correctly predicts the reduction in full energy peak gamma-rays, but does not predict the Compton continuum of a spectrum as a function of height. Therefore, Monte-Carlo simulations should be used to predict the shape and intensity of gamma-ray spectra as a function of height. A finite set of Monte-Carlo simulations at intervals of 5 m were used for the analysis of GRS measurements at heights up to 35 m. The resulting radionuclide concentrations at every height agree with the radionuclide concentration measured on the ground.
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| 8. |
- Söderström, Mats
(författare)
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Optimizing gamma-ray spectrometers for UAV-borne surveys with geophysical applications
- 2021
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 237
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Tidskriftsartikel (refereegranskat)abstract
- Heavy duty unmanned aerial vehicles (UAVs) have made it possible to fly with large gamma-ray spectrometers that weigh several kilograms. Moreover, they can be purchased at an affordable price. These large UAV-borne gamma-ray detection systems are used to map the naturally occurring radionuclides K-40, U-238, Th-232. Such platforms have the advantage that they can be deployed over terrain that is difficult to access, while still maintaining a high spatial resolution. In contrast to UAV-borne radioactive pollution studies, the naturally occurring radionuclides have a much lower activity and therefore require longer integration time, slower flying speed or a larger detector, in order to effectively determine the spatial radionuclide distribution. Therefore, the question arises: what is the minimum practical detector size required to successfully map K-40, U-238 and Th-232 concentrations from UAV platforms.In this study an agricultural field has been mapped with three different scintillator-based gamma-ray spectrometers: a 2000 ml, 1000 ml, and 350 ml detector. They were mounted together on the same UAV. At a flying height of 20 m and a speed of 5.6 m s(-1) the field was mapped. The various aerial measurements were compared to each other and to the ground-based measurements. The field had a low spatial variation in the K-40 concentration (relative standard deviation (RSD) = 9%) and a larger variation for U-238 and Th-232 concentrations (RSD = 24% and 31% respectively).Radionuclide concentrations have been extracted from the survey data by Full Spectrum Analysis (FSA). Uncertainties and variances of the radionuclides have been determined by using two methods. Firstly, they are calculated directly from the FSA output and secondly they are extracted from a variogram. The latter incorporates spatial variation and was shown to provide a lower uncertainty. When using small detectors, the former approach could lead to the conclusion that the uncertainty is larger than the variance, while the variogram approach does capture the spatial variation.All three detectors were able to characterize the spatial distribution of the Th-232 concentration. It is shown that the Th-232 concentration is a good predictor of the sand and clay fraction of the topsoil in the field. By comparing the UAV-borne measurements to the ground-based measurements it is found that UAV-borne measurements at 20 m height are less sensitive to extreme values than ground-based measurements and they have the tendency to shift to the mean concentration of the area.The results of this study can be used to optimize the detector volume, survey height, and survey speed to maintain an acceptable accuracy for gamma-ray studies with small UAV-borne detectors.
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| 9. |
- Xing, Shan, et al.
(författare)
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Circulation of Circumpolar Deep Water and marine environment traced by I-127 and I-129 speciation in the Amundsen Sea Polynya, Antarctica
- 2020
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Ingår i: Journal of Environmental Radioactivity. - : ELSEVIER SCI LTD. - 0265-931X .- 1879-1700. ; 225
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Tidskriftsartikel (refereegranskat)abstract
- The long-lived anthropogenic I-129 released from human nuclear activities has been widely employed as an effective oceanographic tracer to investigate circulation of water masses in marine environment. Depth profiles of seawater collected from the Amundsen Sea Polynya, Antarctica were analyzed for total I-129 and I-127, as well as their species of iodide and iodate. The measured I-129 concentrations ((1.15-3.43) x 10(6) atoms/L) and I-129/I-127 atomic ratios ((0.53-1.19) x 10(-11)) indicate that anthropogenic I-129 has not only reached the Antarctic surface marine environment but also the deep water due to a strong vertical mixing of water masses. The Circumpolar Deep Water (CDW) flowed southward along continental shelf towards the ice shelf zone (74.25 degrees S) at a depth of 1025 m and then migrated upward and northward to the polynya and finally to the sea ice zone (71.95 degrees S). The maximum upwelling depth of the CDW was around 200 m in the polynya. The source of I-129(-) in the polynya is predominantly the intrusion of source waters rather than the in-situ reduction of iodate by phytoplankton, implying a considerably slow reduction process of iodate to iodide in this region.
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| 10. |
- Xu, Shulan, et al.
(författare)
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Development of a model for radionuclide transport in streams for biosphere assessment purpose
- 2023
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 264
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Tidskriftsartikel (refereegranskat)abstract
- As a part of the overall safety assessment for a geological disposal of radioactive waste, models for different ecosystems are used to evaluate doses to humans and biota from possible radionuclide discharges to the biosphere. In previous safety assessments, transport modelling of radionuclides in running waters such as streams has been much simplified to the extent that only dilution of the inflow of radionuclides has been considered with no regard of any other interactions.Hyporheic exchange flow (HEF) is the flow of surface water in streams that enters the subsurface zone and, after some time, returns to the surface. HEF has been studied for decades. Hyporheic exchange and the residence time in the hyporheic zone are key parameters controlling the transport of radionuclides in a stream. Further-more, recent studies have shown that HEF can reduce the groundwater upwelling area and increase the up -welling velocity in areas closest to the streambed water interface.In this paper, the development of an assessment model describing radionuclide transport with consideration of HEF and deep groundwater upwelling along streams is presented. An approach to parameterising the hyporheic exchange processes into an assessment model is based on a comprehensive study that has been performed in five different Swedish catchments. Sensitivity analyses are performed to explore the effect with consideration of the inflow of radionuclides with regard to HEF and deep groundwater upwelling in a safety assessment perspective. Finally, we include some suggestions for the application of the assessment model to long-term radiological safety assessments.
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| 11. |
- Patriarca, Riccardo, et al.
(författare)
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Framing the FRAM : A literature review on the functional resonance analysis method
- 2020
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Ingår i: Safety Science. - : Elsevier. - 0925-7535 .- 1879-1042. ; 129, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- The development of the Functional Resonance Analysis Method (FRAM) has been motivated by the perceived limitations of fundamentally deterministic and probabilistic approaches to understand complex systems’ behaviour. Congruent with the principles of Resilience Engineering, over recent years the FRAM has been progressively developed in scientific terms, and increasingly adopted in industrial environments with reportedly successful results. Nevertheless, a wide literature review focused on the method is currently lacking. On these premises, this paper aims to summarise all available published research in English about FRAM. More than 1700 documents from multiple scientific repositories were reviewed through a protocol based on the PRISMA review technique. The paper aims to uncover a number of characteristics of the FRAM research, both in terms of the method’s application and of the authors contributing to its development. The systematic analysis explores the method in terms of its methodological aspects, application domains, and enhancements in qualitative and quantitative terms, as well as proposing potential future research directions.
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| 12. |
- Dalin, P., et al.
(författare)
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Studies of noctilucent clouds from the stratosphere during the SONC balloon-borne experiment in 2021
- 2022
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 240
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Tidskriftsartikel (refereegranskat)abstract
- On the night 16–17 August 2021, a balloon-borne experiment called Stratospheric Observations of Noctilucent Clouds (SONC) was successfully performed. A big scientific balloon, having onboard three automated cameras for studies of noctilucent clouds (NLC), was launched to 32.7 km altitude from Esrange (northern Sweden). All three NLC cameras and electronics were completely operational in the stratosphere for more than 10 h at low temperatures of about −30 °C. Two wide angle cameras registered an extended NLC field of about 1700 km long in the twilight sky sector from the north-west to the north-east of Esrange. NLC were of a moderate brightness and were located at high latitudes between 68° and 71°N. The NLC field was located in a cold area (138–142 K) below the frost point temperature (145–148 K) in the mesopause region that was confirmed by Aura/MLS satellite and Esrange lidar measurements. The balloon-borne NLC measurements were accompanied by ground-based lidar and radar measurements. The latter have registered Polar Mesosphere Summer Echoes (PMSE) in the same volume of the summer mesopause along with NLC observed from the stratosphere that has been performed for the first time above northern Scandinavia. We describe the technique and method of the NLC observation from the stratosphere as well as present the first scientific results of the SONC experiment.
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| 13. |
- Dubbelboer, Ilse R., et al.
(författare)
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Overview of authorized drug products for subcutaneous administration : Pharmaceutical, therapeutic, and physicochemical properties
- 2022
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 173
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing body of research about subcutaneously administered biologics, emphasizing the need for optimized bioavailability predictions. It is important to inform both translational and in silico models with properties of the drug products and compounds. However, the pharmaceutical, therapeutic and physicochemical properties of market authorized drug products for subcutaneous administration are currently not collated in the public domain. We provide an overview of subcutaneous administered drug products for humans and animals market authorized in EU, Canada, and the US. Data on the drug products were collected from the respective authorities, i.e. European Medicines Agency, Health Canada, and U.S. Food and Drug Administration. Physicochemical properties of active substances were gathered from DrugBank. Human drug products were often indicated for treatment of diabetes and anemia. EU veterinary drug products were often immunologicals. Canadian and US veterinary drug products often acted as antiinfectives for systemic use, on the genito-urinary system or as sex hormones. The final dataset with >1700 subcutaneous drug products is provided. In EU drug products, the majority of active substances were biologics. In the US, drug products most often contained small molecules. Solutions, emulsions and suspensions were the most common dosage forms. A minority of subcutaneous drug products were also registered for intramuscular or intravenous administration. The analysis presented here could aid further research, exploring formulation properties, prescription or sales of market authorized SC drug products and development of inclusive in silico models.
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