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Sökning: WFRF:(Oughton D. H.)

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  • Garnier-Laplace, J., et al. (författare)
  • Issues and practices in the use of effects data from FREDERICA in the ERICA Integrated Approach
  • 2008
  • Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 99:9, s. 1474-1483
  • Tidskriftsartikel (refereegranskat)abstract
    • The ERICA Integrated Approach requires that a risk assessment screening dose rate is defined for the risk characterisation within Tiers 1 and 2. At Tier 3, no numerical screening dose rate is used, and the risk characterisation is driven by methods that can evaluate the possible effects of ionising radiation on reproduction, mortality and morbidity. Species sensitivity distribution has been used to derive the ERICA risk assessment predicted no-effect dose rate (PNEDR). The method used was based on the mathematical processing of data from FRED (FASSET radiation effects database merged with the EPIC database to form FREDERICA) and resulted in a PNEDR of 10 mu Gy/h. This rate was assumed to ascribe sufficient protection of all ecosystems from detrimental effects on structure and function under chronic exposure. The value was weighed against a number of points of comparison: (i) PNEDR values obtained by application of the safety factor method, (ii) background levels, (iii) dose rates triggering effects on radioactively contaminated sites and (iv) former guidelines from literature reviews. In Tier 3, the effects analysis must be driven by the problem formulation and is thus highly case specific. Instead of specific recommendations on numeric values, guidance on the sorts of methods that may be applied for refined effect analysis is Provided and illustrated.
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5.
  • Kleja, D. B., et al. (författare)
  • Assessment of isotopically exchangeable Al in soil materials using Al-26 tracer
  • 2005
  • Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 69:22, s. 5263-5277
  • Tidskriftsartikel (refereegranskat)abstract
    • The solubility of aluminium (Al) in many acidic soils is controlled by complexation reactions with soil organic matter. In such soils, Al solubility is theoretically a function of the pool size of active Al, i.e., the total amount of Al that equilibrates with the sod solution within a defined period of time. To date, no reliable measurements of active Al in soil materials exist. In this study, we determined the isotopically exchangeable pool of Al (E-A1) as an operationally defined assessment of active Al in acidic mineral soils. The suitability of CuCl2 and pyrophosphate (Na4P2O7) as extractants for active Al was also evaluated. Eleven samples, mostly from spodic B horizons, were spiked with carrier-free Al-26 and equilibrated for different time periods (1-756 h). The size of the Al pool with which the Al-26 tracer exchanged increased with time during the whole experimental period. Thus, contact time between solid and solution phases needs to be defined when assessing the active Al pool. Values of E-A1 obtained after I to 5 d of equilibration were equal to the amount of CuCl2 extractable Al, but considerably smaller than the Na4P2O7-extractable pool. Equilibration times greater than 5 d resulted in CuCl2 extractable Al concentrations that under-estimated the active Al pool. Three of the investigated samples were rich in imogolite-type materials (ITM). In these samples, 30-50 % of the added Al-26 rapidly became associated with soil constituents in forms that could not be extracted by Na4P2O7, indicating that a part of ITM may be in a dynamic state.
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6.
  • Oughton, D. H., et al. (författare)
  • Addressing uncertainties in the ERICA Integrated Approach
  • 2008
  • Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 99:9, s. 1384-1392
  • Tidskriftsartikel (refereegranskat)abstract
    • Like any complex environmental problem, ecological risk assessment of the impacts of ionising radiation is confounded by uncertainty. At all stages, from problem formulation through to risk characterisation, the assessment is dependent on models, scenarios, assumptions and extrapolations. These include technical uncertainties related to the data used, conceptual uncertainties associated with models and scenarios, as well as social uncertainties such as economic impacts, the interpretation of legislation, and the acceptability of the assessment results to stakeholders. The ERICA Integrated Approach has been developed to allow an assessment of the risks of ionising radiation, and includes a number of methods that are intended to make the uncertainties and assumptions inherent in the assessment more transparent to users and stakeholders. Throughout its development, ERICA has recommended that assessors deal openly with the deeper dimensions of uncertainty and acknowledge that uncertainty is intrinsic to complex systems. Since the tool is based on a tiered approach, the approaches to dealing with uncertainty vary between the tiers, ranging from a simple, but highly conservative screening to a full probabilistic risk assessment including sensitivity analysis. This paper gives on overview of types of uncertainty that are manifest in ecological risk assessment and the ERICA Integrated Approach to dealing with some of these uncertainties.
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7.
  • Alonzo, Frederic, et al. (författare)
  • Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations
  • 2008
  • Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 99:9, s. 1464-1473
  • Tidskriftsartikel (refereegranskat)abstract
    • This study evaluated the potential effect of ionising radiation on population growth using simple population models and parameter values derived from chronic exposure experiments in two invertebrate species with contrasting life-history strategies. In the earthworm Eisenia fetida, models predicted increasing delay in population growth with increasing gamma dose rate (up to 0.6 generation times at 11 mGy h(-1)). Population extinction was predicted at 43 mGy h(-1). In the microcrustacean Daphnia magna, models predicted increasing delay in population growth with increasing alpha dose rate (up to 0.8 generation times at 15.0 mGy h(-1)), only after two successive generations were exposed. The study examined population effects of changes in different individual endpoints (including survival, number of offspring produced and time to first reproduction). Models showed that the two species did not respond equally to equivalent levels of change, the fast growing daphnids being more susceptible to reduction in fecundity or delay in reproduction than the slow growing earthworms. This suggested that susceptibility of a population to ionising radiation cannot be considered independent of the species' life history.
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8.
  • Hinton, T. G., et al. (författare)
  • An invitation to contribute to a strategic research agenda in radioecology
  • 2013
  • Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 115, s. 73-82
  • Tidskriftsartikel (refereegranskat)abstract
    • With intentions of integrating a portion of their respective research efforts into a trans-national programme that will enhance radioecology, eight European organisations recently formed the European Radioecology ALLIANCE (www.er-alliance.org). The ALLIANCE is an Association open to other organisations throughout the world with similar interests in promoting radioecology. The ALLIANCE members recognised that their shared radioecological research could be enhanced by efficiently pooling resources among its partner organizations and prioritising group efforts along common themes of mutual interest. A major step in this prioritisation process was to develop a Strategic Research Agenda (SRA). An EC-funded Network of Excellence in Radioecology, called STAR (Strategy for Allied Radioecology), was formed, in part, to develop the SRA. This document is the first published draft of the SRA. The SRA outlines a suggested prioritisation of research topics in radioecology, with the goal of improving research efficiency and more rapidly advancing the science. It responds to the question: What topics, if critically addressed over the next 20 years, would significantly advance radioecology? The three Scientific Challenges presented within the SRA, with their 15 associated research lines, are a strategic vision of what radioecology can achieve in the future. Meeting these challenges will require a directed effort and collaboration with many organisations the world over. Addressing these challenges is important to the advancement of radioecology and in providing scientific knowledge to decision makers. Although the development of the draft SRA has largely been a European effort, the hope is that it will initiate an open dialogue within the international radioecology community and its stakeholders. This is an abbreviated document with the intention of introducing the SRA and inviting contributions from interested stakeholders. Critique and input for improving the SRA are welcomed via a link on the STAR website (www.star-radioecology.org).
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