The Experts below are selected from a list of 28665 Experts worldwide ranked by ideXlab platform
Michael D Pirie - One of the best experts on this subject based on the ideXlab platform.
-
leaps and bounds geographical and ecological distance constrained the colonisation of the afrotemperate by Erica
BMC Evolutionary Biology, 2019Co-Authors: Michael D Pirie, Martha Kandziora, Nicolai M Nurk, Nicholas Le C Maitre, Ana Mugrabi De Kuppler, Berit GehrkeAbstract:The coincidence of long distance dispersal (LDD) and biome shift is assumed to be the result of a multifaceted interplay between geographical distance and ecological suitability of source and sink areas. Here, we test the influence of these factors on the dispersal history of the flowering plant genus Erica (Ericaceae) across the Afrotemperate. We quantify similarity of Erica climate niches per biogeographic area using direct observations of species, and test various colonisation scenarios while estimating ancestral areas for the Erica clade using parametric biogeographic model testing. We infer that the overall dispersal history of Erica across the Afrotemperate is the result of infrequent colonisation limited by geographic proximity and niche similarity. However, the Drakensberg Mountains represent a colonisation sink, rather than acting as a “stepping stone” between more distant and ecologically dissimilar Cape and Tropical African regions. Strikingly, the most dramatic examples of species radiations in Erica were the result of single unique dispersals over longer distances between ecologically dissimilar areas, contradicting the rule of phylogenetic biome conservatism. These results highlight the roles of geographical and ecological distance in limiting LDD, but also the importance of rare biome shifts, in which a unique dispersal event fuels evolutionary radiation.
-
leaps and bounds geographical and ecological distance constrained the colonisation of the afrotemperate by Erica
bioRxiv, 2018Co-Authors: Michael D Pirie, Martha Kandziora, Nicolai M Nurk, Nicholas Le C Maitre, Ana Mugrabi De Kuppler, Berit Gehrke, Edward G H Oliver, Dirk U BellstedtAbstract:The coincidence of long distance dispersal and biome shift is assumed to be the result of a multifaceted interplay between geographical distance and ecological suitability of source and sink areas. Here, we test the influence of these factors on the dispersal history of the flowering plant genus Erica (Ericaceae) across the Afrotemperate. We quantify similarity of Erica climate niches per biogeographic area using direct observations of species, and test various colonisation scenarios while estimating ancestral areas for the Erica clade using parametric biogeographic model testing. We infer that the overall dispersal history of Erica across the Afrotemperate is the result of infrequent colonisation limited by geographic proximity and/or niche similarity. However, the Drakensberg Mountains represent a colonisation sink, rather than acting as a "stepping stone" between more distant and ecologically dissimilar Cape and Tropical African regions; and strikingly, the most dramatic examples of species radiations in Erica were the result of single unique dispersals over longer distances between ecologically dissimilar areas, contradicting the rule of phylogenetic biome conservatism. These results highlight the importance of rare biome shifts, in which a unique dispersal event fuels evolutionary radiations.
-
the biodiversity hotspot as evolutionary hot bed spectacular radiation of Erica in the cape floristic region
BMC Evolutionary Biology, 2016Co-Authors: Michael D Pirie, E G H Oliver, Martha Kandziora, Berit Gehrke, Mugrabi A De Kuppler, N Le C Maitre, Dirk U BellstedtAbstract:The disproportionate species richness of the world’s biodiversity hotspots could be explained by low extinction (the evolutionary “museum”) and/or high speciation (the “hot-bed”) models. We test these models using the largest of the species rich plant groups that characterise the botanically diverse Cape Floristic Region (CFR): the genus Erica L. We generate a novel phylogenetic hypothesis informed by nuclear and plastid DNA sequences of c. 60 % of the c. 800 Erica species (of which 690 are endemic to the CFR), and use this to estimate clade ages (using RELTIME; BEAST), net diversification rates (GEIGER), and shifts in rates of diversification in different areas (BAMM; MuSSE). The diversity of Erica species in the CFR is the result of a single radiation within the last c. 15 million years. Compared to ancestral lineages in the Palearctic, the rate of speciation accelerated across Africa and Madagascar, with a further burst of speciation within the CFR that also exceeds the net diversification rates of other Cape clades. Erica exemplifies the “hotbed” model of assemblage through recent speciation, implying that with the advent of the modern Cape a multitude of new niches opened and were successively occupied through local species diversification.
-
a densely sampled its phylogeny of the cape flagship genus Erica l suggests numerous shifts in floral macro morphology
Molecular Phylogenetics and Evolution, 2011Co-Authors: Michael D Pirie, E G H Oliver, Dirk U BellstedtAbstract:Erica L. is the largest of the 'Cape' clades that together comprise around half of the disproportionately high species richness of the Cape Floristic Region (CFR) of South Africa. Around 840 species of Erica are currently recognised, C.680 of which are found in the CFR, the rest distributed across the rest of Southern Africa, the highlands of Tropical Africa and Madagascar, and Europe. Erica is taxonomically well documented, but very little is known about species-level relationships. We present the first densely sampled phylogenetic analysis of Erica, using nuclear ribosomal DNA sequences (internal transcribed spacers; ITS) of c. 45% of the species from across the full geographic range of the genus, both Calluna and Daboecia (Ericeae; monotypic genera and putative sister groups of Erica), and further Ericoideae outgroups. Our results show both morphological and geographic coherence of some clades, but numerous shifts in floral macro-morphology as represented by variation in individual morphological characters and pollination syndromes. European Ericeae is a paraphyletic grade subtending a monophyletic African/Malagasy Erica. Given the limited resolution of this single gene tree, more data are needed for further conclusions. Clades are identified that will serve as an effective guide for targeted sampling from multiple linkage groups.
Dirk U Bellstedt - One of the best experts on this subject based on the ideXlab platform.
-
leaps and bounds geographical and ecological distance constrained the colonisation of the afrotemperate by Erica
bioRxiv, 2018Co-Authors: Michael D Pirie, Martha Kandziora, Nicolai M Nurk, Nicholas Le C Maitre, Ana Mugrabi De Kuppler, Berit Gehrke, Edward G H Oliver, Dirk U BellstedtAbstract:The coincidence of long distance dispersal and biome shift is assumed to be the result of a multifaceted interplay between geographical distance and ecological suitability of source and sink areas. Here, we test the influence of these factors on the dispersal history of the flowering plant genus Erica (Ericaceae) across the Afrotemperate. We quantify similarity of Erica climate niches per biogeographic area using direct observations of species, and test various colonisation scenarios while estimating ancestral areas for the Erica clade using parametric biogeographic model testing. We infer that the overall dispersal history of Erica across the Afrotemperate is the result of infrequent colonisation limited by geographic proximity and/or niche similarity. However, the Drakensberg Mountains represent a colonisation sink, rather than acting as a "stepping stone" between more distant and ecologically dissimilar Cape and Tropical African regions; and strikingly, the most dramatic examples of species radiations in Erica were the result of single unique dispersals over longer distances between ecologically dissimilar areas, contradicting the rule of phylogenetic biome conservatism. These results highlight the importance of rare biome shifts, in which a unique dispersal event fuels evolutionary radiations.
-
the biodiversity hotspot as evolutionary hot bed spectacular radiation of Erica in the cape floristic region
BMC Evolutionary Biology, 2016Co-Authors: Michael D Pirie, E G H Oliver, Martha Kandziora, Berit Gehrke, Mugrabi A De Kuppler, N Le C Maitre, Dirk U BellstedtAbstract:The disproportionate species richness of the world’s biodiversity hotspots could be explained by low extinction (the evolutionary “museum”) and/or high speciation (the “hot-bed”) models. We test these models using the largest of the species rich plant groups that characterise the botanically diverse Cape Floristic Region (CFR): the genus Erica L. We generate a novel phylogenetic hypothesis informed by nuclear and plastid DNA sequences of c. 60 % of the c. 800 Erica species (of which 690 are endemic to the CFR), and use this to estimate clade ages (using RELTIME; BEAST), net diversification rates (GEIGER), and shifts in rates of diversification in different areas (BAMM; MuSSE). The diversity of Erica species in the CFR is the result of a single radiation within the last c. 15 million years. Compared to ancestral lineages in the Palearctic, the rate of speciation accelerated across Africa and Madagascar, with a further burst of speciation within the CFR that also exceeds the net diversification rates of other Cape clades. Erica exemplifies the “hotbed” model of assemblage through recent speciation, implying that with the advent of the modern Cape a multitude of new niches opened and were successively occupied through local species diversification.
-
a densely sampled its phylogeny of the cape flagship genus Erica l suggests numerous shifts in floral macro morphology
Molecular Phylogenetics and Evolution, 2011Co-Authors: Michael D Pirie, E G H Oliver, Dirk U BellstedtAbstract:Erica L. is the largest of the 'Cape' clades that together comprise around half of the disproportionately high species richness of the Cape Floristic Region (CFR) of South Africa. Around 840 species of Erica are currently recognised, C.680 of which are found in the CFR, the rest distributed across the rest of Southern Africa, the highlands of Tropical Africa and Madagascar, and Europe. Erica is taxonomically well documented, but very little is known about species-level relationships. We present the first densely sampled phylogenetic analysis of Erica, using nuclear ribosomal DNA sequences (internal transcribed spacers; ITS) of c. 45% of the species from across the full geographic range of the genus, both Calluna and Daboecia (Ericeae; monotypic genera and putative sister groups of Erica), and further Ericoideae outgroups. Our results show both morphological and geographic coherence of some clades, but numerous shifts in floral macro-morphology as represented by variation in individual morphological characters and pollination syndromes. European Ericeae is a paraphyletic grade subtending a monophyletic African/Malagasy Erica. Given the limited resolution of this single gene tree, more data are needed for further conclusions. Clades are identified that will serve as an effective guide for targeted sampling from multiple linkage groups.
D Copplestone - One of the best experts on this subject based on the ideXlab platform.
-
application of the Erica integrated approach to the drigg coastal sand dunes
Journal of Environmental Radioactivity, 2008Co-Authors: M H Wood, N A Beresford, William A Marshall, Steve R Jones, B J Howard, D Copplestone, Richard T LeahAbstract:The EC-funded project ‘Environmental Risks from Ionising Contaminants: Assessment and Management’ (Erica) developed an ‘Integrated Approach’ for assessing the impact of ionising radiation on ecosystems. This paper presents the application of the Erica Integrated Approach, supported by a software programme (the Erica Tool) and guidance documentation, to an assessment of the Drigg coastal sand dunes (Cumbria, UK). Targeted sampling provided site-specific data for sand dune biota, including amphibians and reptiles. Radionuclides reported included 90Sr, 99Tc, 137Cs, 238Pu, 239+240Pu and 241Am. Site-specific data were compared to predictions derived using the Erica Tool. Some under- and over-predictions of biota activity concentrations were identified but can be explained by the specific ecological characteristics and contamination mechanism of the dunes. Overall, the results indicated no significant impact of ionising radiation on the sand dune biota and the Integrated Approach was found to be a flexible and effective means of conducting a radiation impact assessment.
-
the Erica tool
Journal of Environmental Radioactivity, 2008Co-Authors: J E Brown, N A Beresford, D Copplestone, Boris Alfonso, R Avila, G Prohl, A UlanovskyAbstract:The Erica Tool is a computerised, flexible software system that has a structure based upon the Erica Integrated Approach to assessing the radiological risk to biota. The Tool guides the user through the assessment process, recording information and decisions and allowing the necessary calculations to be performed to estimate risks to selected animals and plants. Tier 1 assessments are media concentration based and use pre-calculated environmental media concentration limits to estimate risk quotients. Tier 2 calculates dose rates but allows the user to examine and edit most of the parameters used in the calculation including concentration ratios, distribution coefficients, percentage dry weight soil or sediment, dose conversion coefficients, radiation weighting factors and occupancy factors. Tier 3 offers the same flexibility as Tier 2 but allows the option to run the assessment probabilistically if the underling parameter probability distribution functions are defined. Results from the Tool can be put into context using incorporated data on dose-effects relationships and background dose rates.
-
derivation of transfer parameters for use within the Erica tool and the default concentration ratios for terrestrial biota
Journal of Environmental Radioactivity, 2008Co-Authors: N A Beresford, J E Brown, B J Howard, C L Barnett, W A Scott, D CopplestoneAbstract:An ability to predict radionuclide activity concentrations in biota is a requirement of any method assessing the exposure of biota to ionising radiation. Within the Erica Tool fresh weight whole-body activity concentrations in organisms are estimated using concentration ratios (the ratio of the activity concentration in the organism to the activity concentration in an environmental media). This paper describes the methodology used to derive the default terrestrial ecosystem concentration ratio database available within the Erica Tool and provides details of the provenance of each value for terrestrial reference organisms. As the Erica Tool considers 13 terrestrial reference organisms and the radioisotopes of 31 elements, a total of 403 concentration ratios were required for terrestrial reference organisms. Of these, 129 could be derived from literature review. The approaches taken for selecting the remaining values are described. These included, for example, assuming values for similar reference organisms and/or biogeochemically similar elements, and various simple modelling approaches.
-
addressing uncertainties in the Erica integrated approach
Journal of Environmental Radioactivity, 2008Co-Authors: Deborah Oughton, J E Brown, D Copplestone, R Avila, Almudena Aguero, Michael GilekAbstract: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.
-
estimating the exposure of small mammals at three sites within the chernobyl exclusion zone a test application of the Erica tool
Journal of Environmental Radioactivity, 2008Co-Authors: N A Beresford, Deborah Oughton, B J Howard, C L Barnett, S Gaschak, Igor Chizhevsky, G Stromman, S M Wright, Andrey M Maksimenko, D CopplestoneAbstract:An essential step in the development of any modelling tool is the validation of its predictions. This paper describes a study conducted within the Chernobyl exclusion zone to acquire data to conduct an independent test of the predictions of the Erica Tool which is designed for use in assessments of radiological risk to the environment. Small mammals were repeatedly trapped at three woodland sites between early July and mid-August 2005. Thermoluminescent dosimeters mounted on collars were fitted to Apodemus flavicollis, Clethrionomys glareolus and Microtus spp. to provide measurements of external dose rate. A total of 85 TLDs were recovered. All animals from which TLDs were recovered were live-monitored to determine 90Sr and 137Cs whole-body activity concentrations. A limited number of animals were also analysed to determine 239,240Pu activity concentrations. Measurements of whole-body activity concentrations and dose rates recorded by the TLDs were compared to predictions of the Erica-Tool. The predicted 90Sr and 137Cs mean activity concentrations were within an order of magnitude of the observed data means. Whilst there was some variation between sites in the agreement between measurements and predictions this was consistent with what would be expected from the differences in soil types at the sites. Given the uncertainties of conducting a study such as this, the agreement observed between the TLD results and the predicted external dose rates gives confidence to the predictions of the Erica Tool.
Katia Vergetti Bloch - One of the best experts on this subject based on the ideXlab platform.
-
challenges for conducting blood collection and biochemical analysis in a large multicenter school based study with adolescents lessons from Erica in brazil
Cadernos De Saude Publica, 2017Co-Authors: Felipe Vogt Cureau, Gabriela De Azevedo Abreu, Katia Vergetti Bloch, Carlos Henrique Klein, Aline Henz, Camila Wohlgemuth Schaan, Cecilia Lacroix De Oliveira, Denise Tavares Giannini, Elisa Brosina De Leon, Gabriela Heiden TeloAbstract:Abstract: The Study of Cardiovascular Risk in Adolescents (Erica) is a pioneering study that aimed to assess the prevalence of cardiovascular risk factors, including metabolic syndrome components in Brazilian adolescents. This study aims to describe the methodological aspects related to blood collection as well as to report pertaining results of the preparation, transport, storage, and exams in Erica. Exams in Erica were performed in a single laboratory and blood samples were collected in schools in a standardized manner. Logistics involved air transportation of samples to the reference laboratory with controlled temperature since sample collection. The serum was stored in local biorepositories in four centers to be used in future analyses. During the study, 284,247 exams were performed and rate of participation in exams was 56.2%, thus involving 40,732 adolescents. From the total, 92.6% of the samples reached the reference laboratory maintaining the temperature between 0-10°C. No clinical significant changes in results due to temperature changes were identified. External quality control recorded satisfactory results in 98.7% of the evaluations. Four biorepositories with samples of 7,785 adolescents were created. Thus, we can consider that the logistics adopted in Erica was fairly successful and description of this as well as the difficulties experienced in Brazil can inform and facilitate the planning of future studies, especially in developing countries.
-
software to record 24 hour food recall application in the study of cardiovascular risks in adolescents
Revista Brasileira De Epidemiologia, 2016Co-Authors: Laura Augusta Barufaldi, Gabriela De Azevedo Abreu, Gloria Valeria Da Veiga, Rosely Sichieri, Maria Cristina Caetano Kuschnir, Diana Barbosa Cunha, Rosângela Alves Pereira, Katia Vergetti BlochAbstract:Introduction: The Study of Cardiovascular Risk in Adolescents (Erica) is a national multicenter study whose purpose is to describe the cardiovascular risk profile, including obesity, changes in lipid and glucose metabolism, and blood pressure, of about 75,000 Brazilian adolescents. Objective: To describe the development of a tool for data collection of 24-hour food recall (REC24h) in Erica and to report its performance in the pilot study. Methods: The Multiple Pass Method was used for the development of the computer program that guides REC24h interview. REC24h-Erica uses a database composed of 1,626 food items including preparation methods and units of predefined portion sizes. Food consumption data are obtained through interviews and entered directly into REC24h-Erica, avoiding the use of paper. Results: The pilot study included 1,367 adolescents, of which 1,047 (77%) responded to REC24h. The researchers did not report difficulties in program use, the average duration of interviews was 20 minutes and the interviewers inserted 50 new food items. Conclusion: The program developed was proven suitable for use in large-population studies, even in a country like Brazil, where there is great diversity in eating habits.
-
Erica smoking prevalence in brazilian adolescents
Revista De Saude Publica, 2016Co-Authors: Valeska Carvalho Figueiredo, Maria Cristina Caetano Kuschnir, Katia Vergetti Bloch, Andre Salem Szklo, Leticia Casado Costa, Thiago Luiz Nogueira Da Silva, Moyses SzkloAbstract:OBJECTIVE To estimate the prevalences of tobacco use, tobacco experimentation, and frequent smoking among Brazilian adolescents. METHODS We evaluated participants of the cross-sectional, nation-wide, school-based Study of Cardiovascular Risks in Adolescents (Erica), which included 12- to 17-year-old adolescents from municipalities of over 100 thousand inhabitants. The study sample had a clustered, stratified design and was representative of the whole country, its geographical regions, and all 27 state capitals. The information was obtained with self-administered questionnaires. Tobacco experimentation was defined as having tried cigarettes at least once in life. Adolescents who had smoked on at least one day over the previous 30 days were considered current cigarette smokers. Having smoked cigarettes for at least seven consecutive days was an indicator for regular consumption of tobacco. Considering the complex sampling design, prevalences and 95% confidence intervals were estimated according to sociodemographic and socio-environmental characteristics. RESULTS We evaluated 74,589 adolescents. Among these, 18.5% (95%CI 17.7-19.4) had smoked at least once in life, 5.7% (95%CI 5.3-6.2) smoked at the time of the research, and 2.5% (95%CI 2.2-2.8) smoked often. Adolescents aged 15 to 17 years had higher prevalences for all indicators than those aged 12 to 14 years. The prevalences did not differ significantly between sexes. The highest prevalences were found in the South region and the lowest ones, in the Northeast region. Regardless of sex, the prevalences were found to be higher for adolescents who had had paid jobs, who lived with only one parent, and who reported having been in contact with smokers either inside or outside their homes. Female public school adolescents were found to smoke more than the ones from private schools. CONCLUSIONS Tobacco use among adolescents is still a challenge. Intending to reduce the prevalence of tobacco use among young people, especially the ones under socioeconomic vulnerability conditions, Brazil must consolidate and increase effective public health care measures.
-
Erica prevalence of dyslipidemia in brazilian adolescents
Revista De Saude Publica, 2016Co-Authors: Jose Rocha Faria Neto, Gabriela De Azevedo Abreu, Maria Cristina Caetano Kuschnir, Vivian Freitas Rezende Bento, Cristina Pellegrino Baena, Marcia Olandoski, Luis Gonzaga De Oliveira Goncalves, Katia Vergetti BlochAbstract:OBJECTIVE To determine the distribution of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides in Brazilian adolescents, as well as the prevalence of altered levels of such parameters. METHODS Data from the Study of Cardiovascular Risks in Adolescents (Erica) were used. This is a country-wide, school-based cross-sectional study that evaluated 12 to 17-year old adolescents living in cities with over 100,000 inhabitants. The average and distribution of plasma levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides were evaluated. Dyslipidemia was determined by levels of total cholesterol ≥ 170 mg/dl, LDL cholesterol ≥ 130 mg/dl, HDL cholesterol < 45 mg/dL, or triglycerides ≥ 130 mg/dl. The data were analyzed by gender, age, and regions in Brazil. RESULTS We evaluated 38,069 adolescents - 59.9% of females, and 54.2% between 15 and 17 years. The average values found were: total cholesterol = 148.1 mg/dl (95%CI 147.1-149.1), HDL cholesterol = 47.3 mg/dl (95%CI 46.7-47.9), LDL cholesterol = 85.3 mg/dl (95%CI 84.5-86.1), and triglycerides = 77.8 mg/dl (95%CI 76.5-79.2). The female adolescents had higher average levels of total cholesterol, LDL cholesterol, and HDL cholesterol, without differences in the levels of triglycerides. We did not observe any significant differences between the average values among 12 to 14 and 15- to 17-year old adolescents. The most prevalent lipid alterations were low HDL cholesterol (46.8% [95%CI 44.8-48.9]), hypercholesterolemia (20.1% [95%CI 19.0-21.3]), and hypertriglyceridemia (7.8% [95%CI 7.1-8.6]). High LDL cholesterol was found in 3.5% (95%CI 3.2-4.0) of the adolescents. Prevalence of low HDL cholesterol was higher in Brazil's North and Northeast regions. CONCLUSIONS A significant proportion of Brazilian adolescents has alterations in their plasma lipids. The high prevalence of low HDL cholesterol and hypertriglyceridemia, especially in Brazil's North and Northeast regions, must be analyzed in future studies, to support the creation of strategies for efficient interventions.
-
the study of cardiovascular risk in adolescents Erica rationale design and sample characteristics of a national survey examining cardiovascular risk factor profile in brazilian adolescents
BMC Public Health, 2015Co-Authors: Katia Vergetti Bloch, Laura Augusta Barufaldi, Gabriela De Azevedo Abreu, Gloria Valeria Da Veiga, Maria Cristina Caetano Kuschnir, Moyses Szklo, Carlos Henrique Klein, Mauricio Teixeira Leite De Vasconcelos, Valeska Carvalho Figueiredo, Adriano DiasAbstract:The Study of Cardiovascular Risk in Adolescents (Portuguese acronym, “Erica”) is a multicenter, school-based country-wide cross-sectional study funded by the Brazilian Ministry of Health, which aims at estimating the prevalence of cardiovascular risk factors, including those included in the definition of the metabolic syndrome, in a random sample of adolescents aged 12 to 17 years in Brazilian cities with more than 100,000 inhabitants. Approximately 85,000 students were assessed in public and private schools. Brazil is a continental country with a heterogeneous population of 190 million living in its five main geographic regions (North, Northeast, Midwest, South and Southeast). Erica is a pioneering study that will assess the prevalence rates of cardiovascular risk factors in Brazilian adolescents using a sample with national and regional representativeness. This paper describes the rationale, design and procedures of Erica.
N A Beresford - One of the best experts on this subject based on the ideXlab platform.
-
inter comparison of dynamic models for radionuclide transfer to marine biota in a fukushima accident scenario
Journal of Environmental Radioactivity, 2016Co-Authors: Vives J I Batlle, N A Beresford, K Beaugelinseiller, R Bezhenar, J E Brown, J J Cheng, Mirjana Cujic, Snežana Dragovic, Celine Duffa, Bruno FievetAbstract:We report an inter-comparison of eight models designed to predict the radiological exposure of radionuclides in marine biota. The models were required to simulate dynamically the uptake and turnover of radionuclides by marine organisms. Model predictions of radionuclide uptake and turnover using kinetic calculations based on biological half-life (TB1/2) and/or more complex metabolic modelling approaches were used to predict activity concentrations and, consequently, dose rates of 90Sr, 131I and 137Cs to fish, crustaceans, macroalgae and molluscs under circumstances where the water concentrations are changing with time. For comparison, the Erica Tool, a model commonly used in environmental assessment, and which uses equilibrium concentration ratios, was also used. As input to the models we used hydrodynamic forecasts of water and sediment activity concentrations using a simulated scenario reflecting the Fukushima accident releases. Although model variability is important, the intercomparison gives logical results, in that the dynamic models predict consistently a pattern of delayed rise of activity concentration in biota and slow decline instead of the instantaneous equilibrium with the activity concentration in seawater predicted by the Erica Tool. The differences between Erica and the dynamic models increase the shorter the TB1/2 becomes; however, there is significant variability between models, underpinned by parameter and methodological differences between them. The need to validate the dynamic models used in this intercomparison has been highlighted, particularly in regards to optimisation of the model biokinetic parameters.
-
approaches to providing missing transfer parameter values in the Erica tool how well do they work
Journal of Environmental Radioactivity, 2013Co-Authors: J E Brown, N A Beresford, A HosseiniAbstract:Abstract A required parameter for the Erica Tool is the concentration ratio (CR), which is used to describe the transfer from environmental media to a range of organisms. For the original parameterisation of the Erica Tool, 60% of these values were derived using a variety of extrapolation approaches, including the application of allometric models, the use of values for a similar organism or element with similar biogeochemical behaviour and the use of values from a different ecosystem. Although similar approaches are applied in other assessment systems, there has been little attempt to see how well these approaches perform. In this paper, CR values in the Erica Tool derived using extrapolation approaches are compared to more recently available empirical data from the IAEA wildlife transfer database. The primary purpose of the default CR database in the Erica Tool, and other models, is to enable the user to conduct conservative screening assessments. Conservatism was therefore introduced to the analyses by selecting the 95th percentile CR values for subsequent calculations. The extrapolation methodologies are not guaranteed to provide conservative estimates of empirical 95th percentile CRs. For the terrestrial ecosystem, the extrapolation methods provide underpredictions of empirical 95th percentiles as often as they produce overpredictions. In a few cases the underestimation of CR values, when considering all ecosystems, is substantial - by orders of magnitude - which is clearly unacceptable for a screening assessment. Thus, although extrapolation approaches will remain an essential component of screening assessments in the future, because data gaps will always be present, diligence is important in their application. Finally, by synthesizing the results from the current analyses and through other considerations, some recommendations are provided with regards to modifying the original guidance on use of extrapolation approaches in the Erica Tool.
-
application of the Erica integrated approach to the drigg coastal sand dunes
Journal of Environmental Radioactivity, 2008Co-Authors: M H Wood, N A Beresford, William A Marshall, Steve R Jones, B J Howard, D Copplestone, Richard T LeahAbstract:The EC-funded project ‘Environmental Risks from Ionising Contaminants: Assessment and Management’ (Erica) developed an ‘Integrated Approach’ for assessing the impact of ionising radiation on ecosystems. This paper presents the application of the Erica Integrated Approach, supported by a software programme (the Erica Tool) and guidance documentation, to an assessment of the Drigg coastal sand dunes (Cumbria, UK). Targeted sampling provided site-specific data for sand dune biota, including amphibians and reptiles. Radionuclides reported included 90Sr, 99Tc, 137Cs, 238Pu, 239+240Pu and 241Am. Site-specific data were compared to predictions derived using the Erica Tool. Some under- and over-predictions of biota activity concentrations were identified but can be explained by the specific ecological characteristics and contamination mechanism of the dunes. Overall, the results indicated no significant impact of ionising radiation on the sand dune biota and the Integrated Approach was found to be a flexible and effective means of conducting a radiation impact assessment.
-
the Erica tool
Journal of Environmental Radioactivity, 2008Co-Authors: J E Brown, N A Beresford, D Copplestone, Boris Alfonso, R Avila, G Prohl, A UlanovskyAbstract:The Erica Tool is a computerised, flexible software system that has a structure based upon the Erica Integrated Approach to assessing the radiological risk to biota. The Tool guides the user through the assessment process, recording information and decisions and allowing the necessary calculations to be performed to estimate risks to selected animals and plants. Tier 1 assessments are media concentration based and use pre-calculated environmental media concentration limits to estimate risk quotients. Tier 2 calculates dose rates but allows the user to examine and edit most of the parameters used in the calculation including concentration ratios, distribution coefficients, percentage dry weight soil or sediment, dose conversion coefficients, radiation weighting factors and occupancy factors. Tier 3 offers the same flexibility as Tier 2 but allows the option to run the assessment probabilistically if the underling parameter probability distribution functions are defined. Results from the Tool can be put into context using incorporated data on dose-effects relationships and background dose rates.
-
derivation of transfer parameters for use within the Erica tool and the default concentration ratios for terrestrial biota
Journal of Environmental Radioactivity, 2008Co-Authors: N A Beresford, J E Brown, B J Howard, C L Barnett, W A Scott, D CopplestoneAbstract:An ability to predict radionuclide activity concentrations in biota is a requirement of any method assessing the exposure of biota to ionising radiation. Within the Erica Tool fresh weight whole-body activity concentrations in organisms are estimated using concentration ratios (the ratio of the activity concentration in the organism to the activity concentration in an environmental media). This paper describes the methodology used to derive the default terrestrial ecosystem concentration ratio database available within the Erica Tool and provides details of the provenance of each value for terrestrial reference organisms. As the Erica Tool considers 13 terrestrial reference organisms and the radioisotopes of 31 elements, a total of 403 concentration ratios were required for terrestrial reference organisms. Of these, 129 could be derived from literature review. The approaches taken for selecting the remaining values are described. These included, for example, assuming values for similar reference organisms and/or biogeochemically similar elements, and various simple modelling approaches.