| 261. |
- Rääf, Christopher L., et al.
(författare)
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Time‑dependence of decontamination efficiency after a fallout of gamma‑emitting radionuclides in suburban areas: a theoretical outlook on topsoil removal
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Decontamination of urban areas may be necessary in the case of extensive fallout of radioactive material after a nuclear accident, as removal of contaminated soil and vegetation will significantly reduce doses for the residents in an area affected by fallout. Experience from Japan shows that cleanup operations of urban areas may take years despite investment in ample resources. The time delay between the initial fallout and completion of the decontamination measures allows natural and physical processes to affect the results. The efficiency of the decontamination will therefore depend significantly on time. Radioecological modeling and computer simulation of urban topography with one-story houses were applied in this study to estimate action-influenced time-integrated dose reductions (TDR) of contaminated topsoil removal as a function of time after the fallout. Results indicate that the TDR decreases gradually after the fallout depending on the vertical migration rate of radiocesium and, to some extent, the initial 134Cs/137Cs ratio. Delaying the topsoil removal from 1 to 10 years will result in a TDR decrease by more than a factor of two. Removing the topsoil within one year after fallout results typically in an averted effective dose between 34 and 80 mSv per MBq m− 2 deposition of 137Cs for residents in wooden houses. The corresponding values for residents in brick houses are about 50% lower due to higher shielding. Additional modeling is needed to estimate how age and sex influence the averted detriment to affected cohorts. In addition, more in-depth knowledge of how the efficiency of topsoil removal in practice compares with hypothetical models and the effect of incomplete removal of radiocesium is needed to improve calculations of TDR values.
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| 262. |
- 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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| 263. |
- Rääf, Christopher, et al.
(författare)
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Återställning av förorenade områden efter en RN-olycka : Samhällets problem och hur bästa kombination av långsiktiga åtgärder kan väljas för att skydda människor i bebyggda miljöer mot bestrålning
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta projekt har syftat till att ge svenska myndigheter och beslutsfattare enbeskrivning av samhällets problem efter ett kraftigt nedfall av långlivade radioaktivaämnen och hur den bästa kombinationen av åtgärder kan väljas för att skyddamänniskor mot bestrålning med hänsyn till ekonomiska, sociala och samhälleligafaktorer. Arbetet med att återställning av ett tätortsområde som berörts av enomfattande radioaktiv beläggning från en kärnteknisk olycka är en process som kanta många år i anspråk. Initial krishantering av myndigheterna kommer successivtbehöva övergå till långsiktig kontinuerlig riskhantering av de personer som väljer attstanna kvar eller flytta tillbaka till det drabbade området. Denna långsiktigariskhantering kommer också beröra de utrymda personer som väljer att inteåtervända till det sanerade området.I projektet har berättigandet av saneringsåtgärder, samt vilka faktorer som styr huråtgärderna ska optimeras, studerats utifrån ett flervetenskapligt perspektiv.Slutsatserna är att marksanering av bebyggda områden kan vara berättigade ur ettsamhällsperspektiv trots de mycket höga monetära kostnaderna som åtgärdernakräver i relation till de avstyrda stråldoser och cancerfall som kan uppkomma.Möjlighet till återflytt av ett utrymt område styrs i hög grad av de dosvärden sommyndigheternas skyddsåtgärder syftar till att underskrida (s.k. referensnivåer) ochsom finns angivna i svensk myndighetsvägledning (SSM, 2017). Genommarksanering kan stråldoser minskas så att dessa referensnivåer underskrids ochdärmed möjliggöra återflytt till nedfallsdrabbade områden betydligt tidigare än ombara utrymning görs, förutsatt att saneringsåtgärderna görs enligt internationelltrekommenderade metoder.Sanering kan också utgöra en tydlig milstolpe i den långsiktiga riskhanteringen förboende i ett område som berörts av radioaktiv beläggning och utgöra ettplaneringsunderlag för de drabbade individernas fortsatta livsval och bearbetning avolyckan.
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| 264. |
- Salifu, Musah, et al.
(författare)
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Sr/Ca and 87Sr/86Sr : A tracer for geochemical processes in mine wastes
- 2018
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Ingår i: RISK TO OPPORTUNITY. - South Africa : ICARD/IWMA. ; , s. 723-728
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Konferensbidrag (refereegranskat)abstract
- Understanding geochemical processes in mining environments are essential to waste management decisions including remediation. In an attempt to understand geochemical processes, chemical data have mostly been used but these have oft en led to inaccurate conclusions. Th erefore, in this work 87Sr/86Sr, Sr/Ca and other elemental ratios (Ca/K and Rb/Sr) in leachates were employed to constrain the geochemical processes in an abandoned tungsten (W) tailings in Yxsjöberg, South-Central Sweden. Th e results of this study indicate that coupling chemical ratios with 87Sr/86Sr ratios off er better insights in discriminating between diff erent geochemical processes in mine wastes
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| 265. |
- Salifu, Musah, et al.
(författare)
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Strontium (87Sr/86Sr) isotopes: A tracer for geochemical processes in mineralogically-complex mine wastes
- 2018
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 99, s. 42-54
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Tidskriftsartikel (refereegranskat)abstract
- Interpretation of geochemical data based primarily on elemental concentrations often lead to ambiguous results due to multiple potential sources including mineral weathering, atmospheric input, biological cycling, mineral precipitation and exchange processes. The 87Sr/86Sr ratio is however not fractionated by these processes. In this study, Sr isotope (87Sr/86Sr) ratios have been coupled with chemical data of Sr and Rb-bearing minerals, tailings and leachates (water-soluble) to gain insight into the geochemical processes occurring within the Yxsjöberg Cu-W mine tailings, Sweden. The tailings have been exposed to oxidizing conditions resulting in three geochemical zones namely (i) oxidized, (ii) transition and (iii) unoxidized zones. Leachates from the oxidized zone are acidic (pH = 3.6–4.5) and contain elevated concentrations of metals (e.g. Fe, Cu and Zn) and SO4. The low pH has also led to subsequent weathering of most silicates, releasing Al, Ca, Mg and Na into solution. The 87Sr/86Sr ratio in the tailings ranges from 0.84787 to 1.26640 in the oxidized zone, 0.92660–1.06788 in the transition zone, whilst the unoxidized zone has values between 0.76452 and 1.05169. For the leachates, the 87Sr/86Sr ratio ranges from 2.44479 to 5.87552 in the oxidized zone, 1.37404–1.68844 in the transition zone and 1.03697–2.16340 in the unoxidized zone. Mixing (between mineral weathering and atmospheric sources) was identified as the major process regulating the Sr composition of the tailings and leachates. The highly radiogenic signatures of the leachates in the oxidized zone suggests weathering of biotite, K-feldspar and muscovite. Despite the very radiogenic signatures in the oxidized zone, increments in Ca/K ratios, Be, Ce, Tl, Al, Fe and SO4 concentrations in the water-soluble phase were recorded in its lower parts which suggests the dissolution of amphibole, pyroxene, plagioclase, fluorite, gypsum, Al and Fe –(oxy) hydroxides as well as cation exchange by clay minerals. Presence of clay minerals has led to the partial retainment of radiogenic 87Sr/86Sr resulting in increased 87Sr/86Sr in the solid tailings material at these depths. The 87Sr/86Sr ratios of the water-soluble phase in the transition zone is similar to that of helvine and could indicate its dissolution. In the upper part of the oxidized zone, the 87Sr/86Sr ratios and trends of Be, Ca, SO4, Tl and Zn in the water-soluble phase suggest the dissolution of gypsum which precipitated from a leachate with the isotopic signature of helvine. In the lower part of the unoxidized zone, elevated concentrations of W were recorded suggesting scheelite weathering. But the 87Sr/86Sr ratios are higher than that expected from dissolution of scheelite and indicates additional processes. Possible sources include biotite weathering and groundwater. This study reveals that when interpreting geochemical processes in mine waste environments, 87Sr/86Sr should be considered in addition to chemical constituents, as this isotopic tracer offers better insights into discriminating between different solute sources.
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| 266. |
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| 267. |
- Samuelsson, Christer, et al.
(författare)
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Decontamination after a nuclear fallout: A condensed review of case studies, methods and key references up to 2014
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this work is to provide governmental agencies and the society a condensed overview of the current state of knowledge on the efficiency of applied restoration and remediation of areas affected by radioactive fallout. The most actual real-world case is the Fukushima accident in Japan in 2011: the accident and the following applied decontamination methods are in focus in this review study. This report was written in 2014 and reviewed and translated in 2018/2019. This work was financed by the Swedish Civil Contingencies Agency.
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| 268. |
- Sandvik, Oscar S., et al.
(författare)
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Intercomparison of in-situ aircraft and satellite aerosol measurements in the stratosphere
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Aerosol composition and optical scattering from particles in the lowermost stratosphere (LMS) have been studied by comparing in-situ aerosol samples from the IAGOS-CARIBIC passenger aircraft with vertical profiles of aerosol backscattering obtained from the CALIOP lidar aboard the CALIPSO satellite. Concentrations of the dominating fractions of the stratospheric aerosol, being sulphur and carbon, have been obtained from post-flight analysis of IAGOS-CARIBIC aerosol samples. This information together with literature data on black carbon concentrations were used to calculate the aerosol backscattering which subsequently is compared with measurements by CALIOP. Vertical optical profiles were taken in an altitude range of several kilometres from and above the northern hemispheric extratropical tropopause for the years 2006-2014. We find that the two vastly different measurement platforms yield different aerosol backscattering, especially close to the tropopause where the influence from tropospheric aerosol is strong. The best agreement is found when the LMS is affected by volcanism, i.e., at elevated aerosol loadings. At background conditions, best agreement is obtained some distance (>2 km) above the tropopause in winter and spring, i.e., at likewise elevated aerosol loadings from subsiding aerosol-rich stratospheric air. This is to our knowledge the first time the CALIPSO lidar measurements have been compared to in-situ long-term aerosol measurements.
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| 269. |
- Sandvik, Oscar S., et al.
(författare)
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Methodology to obtain highly resolved SO2 vertical profiles for representation of volcanic emissions in climate models
- 2021
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 14:11, s. 7153-7165
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Tidskriftsartikel (refereegranskat)abstract
- In this study we describe a methodology to create high-vertical-resolution SO2 profiles from volcanic emissions. We demonstrate the method's performance for the volcanic clouds following the eruption of Sarychev in June 2009. The resulting profiles are based on a combination of satellite SO2 and aerosol retrievals together with trajectory modelling. We use satellite-based measurements, namely lidar backscattering profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite instrument, to create vertical profiles for SO2 swaths from the Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite. Vertical profiles are created by transporting the air containing volcanic aerosol seen in CALIOP observations using the FLEXible PARTicle dispersion model (FLEXPART) while preserving the high vertical resolution using the potential temperatures from the MERRA-2 (Modern-Era Retrospective analysis for Research and Application) meteorological data for the original CALIOP swaths. For the Sarychev eruption, air tracers from 75 CALIOP swaths within 9g d after the eruption are transported forwards and backwards and then combined at a point in time when AIRS swaths cover the complete volcanic SO2 cloud. Our method creates vertical distributions for column density observations of SO2 for individual AIRS swaths, using height information from multiple CALIOP swaths. The resulting dataset gives insight into the height distribution in the different sub-clouds of SO2 within the stratosphere. We have compiled a gridded high-vertical-resolution SO2 inventory that can be used in Earth system models, with a vertical resolution of 1g K in potential temperature, 61g g 56g m, or 1.8g g 2.9g mbar.
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| 270. |
- Schmidl, Helen, 1975-
(författare)
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Från vildmark till grön ängel : Receptionsanalyser av läsning i åttonde klass
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The subject of this dissertation is Swedish upper secondary pupils’ reception of novels read as part of their literature instruction. The main purpose is to study and compare the reading of female pupils with that of male pupils and to analyze to what extent attention is paid to their private reading experiences in the literary teaching. What strategies do the students use to interpret and discuss fiction? And what is the relationship between their private reading habits and the way fiction is studied at school? Consequently, the subject field of this qualitative study concerns not only teenagers’ private reading habits, but also gender related issues, school adjusted reading routines and didactic matters.Reading at school differs in many ways from the pupils’ private reading habits, but there are also differences regarding the students’ attitudes towards reading as such. There proved to be certain diversities between the reading habits of boys and girls. The boys read in general less than the girls, and many boys were interested in reading adventurous and exciting stories. The girls were more into reading realistic novels, and to them it was important that they could identify with the characters. Many pupils responded personally to their reading. Instead of reflecting on the meaning of a text and comparing it to other texts or phenomena of the surrounding world, their reception confined itself to categories like “boring” or “exciting”. Merely a few students included a more profound literary analysis in their responses.An important aim of literature instruction must be to broaden the pupils’ literary repertoires and to make them improve their reading skills. This study shows that to achieve these improvements the students must feel involved, which means that literature instruction must be adapted to the literary cultures of both boys and girls.
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