Papers by Tamara Yankovich
Application of the International System of Radiation Protection in Fit-for-Purpose Assessment of Impacts
NATO Science for Peace and Security Series A: Chemistry and Biology, 2022
Radioprotection, 2005
Temporal changes in radionuclide transfer factors were evaluated in forage fishes over a 40-to 50... more Temporal changes in radionuclide transfer factors were evaluated in forage fishes over a 40-to 50-year period. In general, 90 Sr, 60 Co and 137 Cs transfer factors fairly consistent over time, as indicated by strong correlations between measured and estimated values. This conclusion was further strengthened by comparing radionuclide transfer factors measured in Perch Lake biota relative to those reported for other Canadian Shield lakes, since similar values were found. Despite these similarities, however, within-lake differences of up to an order of magnitude were observed for a given species collected in a given year, suggesting that within lakes, there may be factors influencing biota exposure to radionuclides and/or bioavailability.
Radioprotection, 2002
There is a growing interest in assessing risk to non-human biota following exposure to radionucli... more There is a growing interest in assessing risk to non-human biota following exposure to radionuclides. However, before dose to aquatic biota can be determined, it is critical to have a solid understanding of radionuclide concentrations in key environmental phases due to their importance in determining external and internal dose. Further understanding of a system can be reached by monitoring temporal changes in radionuclide levels in these phases, especially if assessing the success of remediation activities. The current study has focused on estimating inputs of 90 Sr, 137 Cs and 60 Co to the sediments of a small, Canadian Shield lake located downstream of two Waste Management Areas at AECL's, Chalk River Laboratories site over a 40-year period. Overall, it was found that 137 Cs and 60 Co inputs have declined in the lake over the last 40 years, which resulted in a net depletion of these radionuclides from the sediments over time. Strontium-90 inputs have remained fairly constant over this time period with 90 Sr retention in lake sediments of approximately 15%. It is expected that benthic biota will receive approximately a 2-to 6-fold higher radionuclide dose than pelagic organisms, on average, particularly when feeding in the depositional zone of the lake.
Effects of Ionizing Radiation Combined with Other Stressors, on Non-Human Biota
NATO Science for Peace and Security Series C: Environmental Security
Exposure of organisms in the environment to ionizing radiation is generally considered to be harm... more Exposure of organisms in the environment to ionizing radiation is generally considered to be harmful, regardless of the dose. This assumption derives directly from the basic assumption used for human radiation protection, that harm is directly proportional to dose, without a threshold. The consequence of combined exposures is generally unknown, but is assumed to be either additive or multiplicative. We
Gunnar Uranium Mine Environmental Remediation: Northern Saskatchewan
Volume 2: Facility Decontamination and Decommissioning; Environmental Remediation; Environmental Management/Public Involvement/Crosscutting Issues/Global Partnering, 2013
ABSTRACT The Gunnar Mine and mill site was the largest of some 38 now-abandoned uranium mines tha... more ABSTRACT The Gunnar Mine and mill site was the largest of some 38 now-abandoned uranium mines that were developed and operated in Northern Saskatchewan, Canada, during the Cold War years. During their operating lifetimes these mines produced large quantities of ore and tailings. The Gunnar mine (open pit and underground) produced over 5 million tonnes of uranium ore and nearly 4.4 million tonnes of mine tailings during its operations from 1955 through 1963. An estimated 2.2 to 2.7 million m3 of waste rock that was generated during the processing of the ore abuts the shores of Lake Athabasca, the 22nd largest lake in the world. After closure in the 1960s, the Gunnar site was abandoned with little to no decommissioning being done. The Saskatchewan Research Council has been contracted to manage the clean-up of these abandoned northern uranium mine and mill sites. The Gunnar Mine, because of the magnitude of tailings and waste rock, is subject to an environmental site assessment process regulated by both provincial and federal governments. This process requires a detailed study of the environmental impacts that have resulted from the mining activities and an analysis of projected impacts from remediation efforts. The environmental assessment process, specific site studies, and public involvement initiatives are all now well underway. Due to the many uncertainties associated with an abandoned site, an adaptive remediation approach, utilizing a decision tree, presented within the environmental assessment documents will be used as part of the site regulatory licensing. A critical early task was dealing with major public safety hazards on the site. The site originally included many buildings that were remnants of a community of approximately 800 people who once occupied the site. These buildings, many of which contained high levels of asbestos, had to be appropriately abated and demolished. Similarly, the original mine head frame and mill site buildings, many of which still contained the original machinery and equipment, also had to be dismantled. Remediation options for the accumulated demolition debris have been assessed, as have remediation options for the waste rock and tailings, all of which form part of the environmental assessment. The regulatory requirements include the environmental assessment processes, a complex public involvement strategy, and licensing from the Canadian Nuclear Safety Commission (CNSC) with the long-term goal of releasing the property in a remediated and stable state to the Province of Saskatchewan. Prescribed environmental and land-use endpoints will be determined based on the environmental assessment studies and remediation options analyzed and implemented. Ultimately, the site will be released into an institutional controls program that will allow long-term government management and monitoring.
Elimination rate constants of 36 PCBs in zebra mussels (Dreissena polymorpha) and exposure dynamics in the Lake St. Clair - Lake Erie corridor
Canadian Journal of Fisheries and Aquatic Sciences, 1995
The elimination kinetics of 36 PCB congeners, ranging in log octanol–water partition coefficients... more The elimination kinetics of 36 PCB congeners, ranging in log octanol–water partition coefficients (log Kow) from 5.60 to 7.50, were determined in zebra mussels (Dreissena polymorpha) with shell lengths from 1.0 to 1.5 cm. Elimination rate constants, based on lipid-normalized data, ranged from 0.172 to 0.042 day−1 and exhibited a significant negative regression with log Kow. Time to 95% steady state ranged from 17.5 to 71.0 days and was used to determine the period over which mussels integrated exposure concentrations. Bioavailable PCB congener concentrations, calculated with a steady-state model, were determined from mussels collected offshore of Middle Sister Island in western Lake Erie. Chemical concentrations in water, estimated using mussels, were within an order of magnitude of direct measurements for congeners with log Kow < 6.6. The rapid elimination kinetics of zebra mussels suggests that these organisms can closely track temporal fluctuations in ambient chemical concentr...
Assessment of doses in contaminated urban areas: modelling exercise based on Fukushima data
Journal of Radiological Protection
State-of-the-art dose assessment models were applied to estimate doses to the population in urban... more State-of-the-art dose assessment models were applied to estimate doses to the population in urban areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident. Assessment results were compared among five models, and comparisons of model predictions with actual measurements were also made. Assessments were performed using both probabilistic and deterministic approaches. Predicted dose distributions for indoor and outdoor workers from a probabilistic approach were in good agreement with the actual measurements. In addition, when the models were applied to assess the doses to the representative person, based on a concept recommended by the International Commission on Radiological Protection and in the International Atomic Energy Agency Safety Standards, it was evident that doses to the representative person obtained with a deterministic approach were always higher than those obtained with a probabilistic approach using the same model.
Urban working groups in the IAEA’s model testing programmes: overview from the MODARIA I and MODARIA II programmes
Journal of Radiological Protection, 2022
The IAEA’s model testing programmes have included a series of Working Groups concerned with model... more The IAEA’s model testing programmes have included a series of Working Groups concerned with modelling radioactive contamination in urban environments. These have included the Urban Working Group of Validation of Environmental Model Predictions (1988–1994), the Urban Remediation Working Group of Environmental Modelling for Radiation Safety (EMRAS) (2003–2007), the Urban Areas Working Group of EMRAS II (2009–2011), the Urban Environments Working Group of (Modelling and Data for Radiological Impact Assessments) MODARIA I (2013–2015), and most recently, the Urban Exposures Working Group of MODARIA II (2016–2019). The overarching objective of these Working Groups has been to test and improve the capabilities of computer models used to assess radioactive contamination in urban environments, including dispersion and deposition processes, short-term and long-term redistribution of contaminants following deposition events, and the effectiveness of various countermeasures and other protective...
Optimization of environmental remediation: How to select and use the Reference Levels
Experimental testing has been conducted to determine the effect of amendment of soil with mineral... more Experimental testing has been conducted to determine the effect of amendment of soil with mineral fertilizer, biochar, and peat on emergence, survival, establishment, and productivity of northern boreal plant species grown on poor substrates in a controlled environment (in greenhouse). Four species (slender wheatgrass, rocky mountain fescue, American vetch, and common yarrow) were grown in pots containing poor sandy soil amended with mineral fertilizer and/or organic amendments (peat or biochar). The greenhouse temperature, lighting and pot watering regimes simulated the conditions of vegetation growing season in northern boreal forest. The trials showed that mineral fertilizer had a limited ability to promote plant growth compared to peat and biochar. Both types of organic amendments had similar positive effects on the establishment of two test species (American vetch and common yarrow) and on the growth of three test species (slender wheatgrass, rocky mountain fescue and American ...
Biochar application for revegetation purposes in northern Saskatchewan was studied to determine i... more Biochar application for revegetation purposes in northern Saskatchewan was studied to determine its effectiveness as a soil amendment in establishing sustainable vegetative soil covers. The abandoned Gunnar Mine Site, located on the northern shore of Lake Athabasca, served as a study area to test the effectiveness of biochar as a soil amendment. Field trials were carried out to compare the effect of biochar and peat application on the growth and establishment of native plant species. The field trials showed that peat promotes vegetation cover establishment better than biochar. Biochar also had a positive effect on vegetation recovery through both establishment of seeded plants and self-establishment of natural invaders (plant species not seeded during the experiment). Peat and biochar had different effects as soil amendments, depending on the plant species. It was shown that both peat and biochar can be used to promote plant establishment and growth, but biochar effectiveness may va...
Most of the safety, performance, or radiological impact assessments concerning either actual or p... more Most of the safety, performance, or radiological impact assessments concerning either actual or potential releases, when they comprise biosphere calculations, use parameters such as transfer or accumulation factors requiring their associated values. One international example is the IAEA SRS No. 19 (2001) on the assessment of routine releases. If future assessment purposes are currently considered, such as those linked to overall environmental impact assessments (Hunter, 2001), most of the current biosphere models still need such parameters and associated values.
Journal of environmental radioactivity, Jan 4, 2015
We will never have data to populate all of the potential radioecological modelling parameters req... more We will never have data to populate all of the potential radioecological modelling parameters required for wildlife assessments. Therefore, we need robust extrapolation approaches which allow us to make best use of our available knowledge. This paper reviews and, in some cases, develops, tests and validates some of the suggested extrapolation approaches. The concentration ratio (CRproduct-diet or CRwo-diet) is shown to be a generic (trans-species) parameter which should enable the more abundant data for farm animals to be applied to wild species. An allometric model for predicting the biological half-life of radionuclides in vertebrates is further tested and generally shown to perform acceptably. However, to fully exploit allometry we need to understand why some elements do not scale to expected values. For aquatic ecosystems, the relationship between log10(a) (a parameter from the allometric relationship for the organism-water concentration ratio) and log(Kd) presents a potential o...
Radioprotection, 2009
There is general international acceptance of the need to demonstrate that the environment is prot... more There is general international acceptance of the need to demonstrate that the environment is protected from ionising radiation. In some countries requirements and guidelines for the protection of non-human biota are already in place. As a consequence a number of models and approaches have been proposed for the estimation of the exposure of non-human biota to ionising radiation. The IAEA EMRAS programme's Biota Working Group has conducted the most comprehensive intercomparison of the predictions of these approaches to date. In this paper, we present an overview of the activities of the Biota Working Group concentrating on its conclusions and recommendations.
An international model validation exercise on radionuclide transfer and doses to freshwater biota
Journal of Radiological Protection, 2010
Under the International Atomic Energy Agency (IAEA)&amp;amp;amp;amp;#39;s EMRAS (Environmenta... more Under the International Atomic Energy Agency (IAEA)&amp;amp;amp;amp;#39;s EMRAS (Environmental Modelling for Radiation Safety) programme, activity concentrations of (60)Co, (90)Sr, (137)Cs and (3)H in Perch Lake at Atomic Energy of Canada Limited&amp;amp;amp;amp;#39;s Chalk River Laboratories site were predicted, in freshwater primary producers, invertebrates, fishes, herpetofauna and mammals using eleven modelling approaches. Comparison of predicted radionuclide concentrations in the different species types with measured values highlighted a number of areas where additional work and understanding is required to improve the predictions of radionuclide transfer. For some species, the differences could be explained by ecological factors such as trophic level or the influence of stable analogues. Model predictions were relatively poor for mammalian species and herpetofauna compared with measured values, partly due to a lack of relevant data. In addition, concentration ratios are sometimes under-predicted when derived from experiments performed under controlled laboratory conditions representative of conditions in other water bodies.
Background dose-rates to reference animals and plants arising from exposure to naturally occurring radionuclides in aquatic environments
Journal of Radiological Protection, 2010
In order to put dose-rates derived in environmental impact assessments into context, the Internat... more In order to put dose-rates derived in environmental impact assessments into context, the International Commission on Radiological Protection (ICRP) has recommended the structuring of effects data according to background exposure levels. The ICRP has also recommended a suite of reference animals and plants (RAPs), including seven aquatic organisms, for use within their developing framework. In light of these propositions, the objective of this work was to collate information on activity concentrations of naturally occurring primordial radionuclides for marine and freshwater ecosystems and apply appropriate dosimetry models to derive absorbed dose-rates. Although coverage of activity concentration data is comprehensive for sediment and water, few, or in some cases no, data were found for some RAPs, e.g. for frogs (Ranidae) and freshwater grasses (Poaceae) for most radionuclides. The activity concentrations for individual radionuclides in both organisms and their habitat often exhibit standard deviations that are substantially greater than arithmetic mean values, reflecting large variability in activity concentrations. To take account of variability a probabilistic approach was adopted. The dominating radionuclides contributing to exposure in the RAPs are (40)K, (210)Po and (226)Ra. The mean unweighted and weighted dose-rates for aquatic RAPs are in the ranges 0.07-0.39 microGy h(-1) and 0.37-1.9 microGy h(-1) respectively.
IAEA Initiatives Supporting Good Practice in Uranium Mining Worldwide
Uranium - Past and Future Challenges, 2014
Recognizing the environmental impacts of mining and associated industries and their minimization ... more Recognizing the environmental impacts of mining and associated industries and their minimization has become more important over the last two or three decades. The International Atomic Energy Agency (IAEA) supports good practice in uranium mining and milling worldwide. As well as its well-known safety standards for radiation protection and waste management, it has produced guidance and acted as a gatherer and provider of information on geological, technological, environmental and regulatory aspects of the uranium production cycle. It is involved in a number of Technical Cooperation projects on this and related topics throughout the world.
Environmental Pollution, 2015
The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the... more The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
Radioprotection, 2009
Conservative no-effect concentrations were derived for nine radionuclides, four generic organisms... more Conservative no-effect concentrations were derived for nine radionuclides, four generic organisms (terrestrial plant and animal and aquatic plant and animal) and six environmental compartments (air, soil, fresh water, marine water, freshwater sediments and marine sediments). The concentrations were calculated using the concentration ratio (CR) approach that is used in both FASSET and RESRAD-BIOTA. In the CR approach, a single transfer factor is used to predict concentrations in plants or animals from concentrations in soil or water. Most of the CR values required for the calculations were taken from FASSET documentation. Because of the importance of tritium and C-14 in the context of CANDU reactors, CR values for these radionuclides were derived from specific activity (SA) concepts. Sediment partition coefficient (K d ) values, which were used to derive no-effect levels for sediments from the levels for water, were chosen to be the best-estimate values from the IMPACT database. Dose conversion coefficients (DCCs) were taken from FASSET and the dose rate benchmarks used were those recommended by UNSCEAR. The results provide environmental concentrations below which no detrimental effects are expected on non-human biota at CANDU sites in Canada. * In most cases, the air concentrations of HTO and C-14 are available and can be used to ensure the protection of biota. In rare cases where soil concentrations are required, they can be calculated using the specific activity model. ‡ Unit is Bq/g dissolved inorganic carbon in water for C-14. † Units are Bq/L of sediment water for HTO; and Bq/g total organic carbon in sediment for C-14.
Radiation and Environmental Biophysics, 2010
The NERC and CEH trade marks and logos ('the Trademarks') are registered trademarks of NERC in th... more The NERC and CEH trade marks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner.
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Papers by Tamara Yankovich