[en] It is often desirable to use more than one local coil during a study, as when imaging paired objects such as breasts or temporomandibular joints, or when imaging large objects such as the spine. The authors designed receiver coils utilizing switchable mutually coupled coils to allow the simultaneous use of more than one local coil. This technique places non restrictions on coupling between the local coils and allows different coils to be used on different slices during a single imaging sequence. In addition, the technique is very simple to implement, as it does not require additional preamplifiers or radiofrequency switches

[en] It is often desirable to use more than one local coil during a study, as when imaging paired objects such as breasts or temporomandibular joints, or when imaging large objects such as the spine. The authors designed receiver coils with switchable mutually coupled coils to allow the simultaneous use of more than one local coil. This technique places no restrictions on coupling between the local coils and allows different coils to be used on different sections during a single imaging sequence. The technique is very simple to implement, as it does not require additional preamplifiers or radio frequency switches

[en] The spatial and temporal variation in radiocaesium and ⁹⁰Sr doses to two population groups of the two Northernmost counties of Norway, Troms and Finnmark, following a hypothetical accident at the Kola nuclear power plant (KNPP) have been estimated using a model implemented within a geographical information system. The hypothetical accident assumes a severe loss of coolant accident at the KNPP coincident with meteorological conditions causing significant radionuclide deposition in the two counties. External doses are estimated from ground deposition and the behaviour of the different population groups, and internal doses from predicted food product activity concentrations and dietary consumption data. Doses are predicted for reindeer keepers and other Norwegian inhabitants, taking account of existing ¹³⁷Cs and ⁹⁰Sr deposition but not including the remedial effect of any countermeasures that might be used. The predicted doses, arising mainly from radiocaesium, confirm the Arctic Monitoring and Assessment Programme assessment that residents of the Arctic are particularly vulnerable to radiocaesium contamination, which could persist for many years. External doses are predicted to be negligible compared to ingestion doses. Ingestion doses for reindeer keepers are predicted to exceed 1 mSv y^-1 for several decades primarily due to their high consumption of reindeer meat. Other Norwegians would also be potentially exposed to doses exceeding 1 mSv y^-1 for several years, especially if they consume many local products. Whilst reindeer production is the most important exposure pathway, freshwater fish, lamb meat, dairy products, mushrooms and berries are also significant contributors to predicted ingestion doses. Radionuclide fluxes, defined as the total output of radioactivity in food from an area for a unit time, are dominated by reindeer meat. The results show the need for an effective emergency response, with appropriate countermeasures, should an accident of the scale considered in this paper occur at the KNPP

[en] The application of the critical loads methodology for radioactive contamination of Arctic and sub-arctic ecosystems, where natural and semi-natural food products are important components of the diet of many people, is proposed and discussed. The critical load is herein defined as the amount of radionuclide deposition necessary to produce radionuclide activity concentrations in food products exceeding intervention limits. The high transfer of radiocaesium to reindeer meat gives this product the lowest critical load, even though the intervention limit is relatively high compared with other products. Ecological half-lives of radiocaesium in natural and semi-natural products are often very long, and it is therefore important to take account of contamination already present in the event of an accident affecting areas where such products are important. In particular, the long ecological half-life for radiocaesium in moose meat means that the critical load is highly sensitive to prior deposition. An example of the potential application of the method for emergency preparedness is given for the Chernobyl accident

[en] The basis premise of many radiological assessments is the assumption that the transfer of many radionuclides from soil to herbage and hence animal derived food products is a positive linear relationship for a given set of ecological conditions. However, a number of authors have published results which they conclude demonstrate non-linear transfer of radiocaesium to plants and animals with transfer being highest when soil concentrations are lowest. Whilst we may expect non-linear transfer of radionuclides under homeostatic control or present in comparatively large chemical quantities there appears no credible hypothesis to support such an observation for radiocaesium. In this paper we review those articles which have reported non-linear radiocaesium transfer and also analyse novel data. Mechanisms for the observation as presented in the original works are critically assessed. For instance, some authors have speculated that radiocaesium root uptake is saturated. We suggest that this is unlikely as whilst saturation of root uptake of radiocaesium has been observed above 1.37 mg Cs⁺ L^-1 in growth solutions, concentrations of Cs⁺ in soil solutions are typically <10 μg L^-1, and 1 MBq m^-2 of ¹³⁷Cs will add only 0.3 mg Cs⁺ m^-2. We discuss alternative hypotheses to explain the reported observations and suggest that sampling bias, countermeasure application and statistical chance all contribute to the reported non-linearity in radiocaesium transfer. (author)

[en] There is increasing concern over potential radioactive contamination of the Arctic due to the wide range of nuclear sources. Environmental characteristics of the Arctic also suggest that it may be comparatively vulnerable to contaminants. Here we review collated data and available models for estimating the transfer of radionuclides to terrestrial biota within the Arctic. The most abundant data are for radiocaesium and radiostrontium although many data for natural radionuclides were available from studies in the Arctic. For some radionuclides no data are available for describing transfer to Arctic biota. Allometric-kinetic models have been used to provide estimates of transfer for radionuclide biota combinations for which data were lacking. Predicted values were in good agreement with observed data for some radionuclides (e.g. Cs, U) although less so for others. However, for some radionuclides where comparison appeared poor there were relatively little observed data with which to compare and the models developed were simplistic excluding some potentially important transfer pathways (e.g. soil ingestion). There are no bespoke models to enable the dynamic prediction of radionuclide transfer to Arctic biota. A human food chain model is available which includes limited parameterization for Cs and Sr transfer in Arctic ecosystems. This has been relatively easily adapted to estimate ¹³⁷Cs and ⁹⁰Sr transfer to some Arctic biota and could be readily adapted to other radionuclide-biota combinations. There are many factors of Arctic ecosystems which may influence radionuclide behaviour including short growing seasons, prolonged freezing of soil, and effects of low temperatures on biological rates. However, these are not included within existing predictive models (for human or biota exposure). If exposure to ionising radiation within Arctic ecosystems is to be robustly predicted such factors must be fully understood and properly incorporated into models. (author)

[en] In recent years national and international programmes have proposed a number of frameworks and methodologies to assess the protection of wildlife from ionising radiations. Whilst some of these are now being used by national authorities there has been little attempt to rigorously test their predictions against available data. In part this is because there are few sites where radiation induced effects have been observed. The Chernobyl exclusion zone represents a site where assessment framework predictions from exposure through to effects can be thoroughly tested. In a separate paper, we have tested predictions of terrestrial radionuclide transfer models developed within the EC FP5 project FASSET against available radionuclide activity concentration database for terrestrial biota in the exclusion zone. In this paper we use the dose conversion factors developed within the FASSET project to estimate internal and external doses to biota within the exclusion zone. The estimated doses are then used to predict effects at different biological levels of organisation using the FASSET Radiation Effects Database (FRED); predicted effects are compared to observed effects within the Chernobyl exclusion zone. The observed effects data for the exclusion zone covers organisms from soil biota through to fish and mammals. Results of the comparison are used to make recommendations for future improvements to assessment frameworks. (author)

[en] In recent years, national and international programmes have proposed a number of frameworks and methodologies to assess the protection of wildlife from ionising radiations. Whilst some of these are now being used by national authorities, there has been little attempt to rigorously test their predictions against available data. In part this is because of the lack of sites where radiation induced effects can be observed. One such site is the Chernobyl exclusion zone for which a considerable amount of data are available for a wide range of biota across a gradient of exposure rates. This allows predictions of assessment frameworks, from exposure through to effects, to be thoroughly tested. In this paper we spatially implement terrestrial radionuclide transfer models developed within the EC FP5 project FASSET and test predictions of radionuclide activity concentrations in biota against compiled databases. More than 700 measurements of radionuclide activity concentrations in wild animals made throughout the exclusion zone between 1988 and 2000 are available. These include 8 species of predominantly large mammals and 13 bird species. This is supplemented by approximately 900 measurements of plant components representing the diets of the herbivorous animals sampled. On the basis of comparisons of predicted and observed activity concentrations in this wide range of biota, recommendations for improving the existing transfer models are made. In a second paper we consider predictions of dose and radiation induced effects and compare these to data from the exclusion zone. (author)

[en] Iceland was identified in the Arctic Monitoring and Assessment Programme (AMAP) as one of the Arctic areas which received the most global fallout from atmospheric nuclear weapons tests, due to relatively high precipitation rates compared with much of the Arctic and sub arctic. Cs-137 in the Icelandic terrestrial ecosystem almost entirely originates from the nuclear weapons tests carried out in the atmosphere until the early sixties. Fallout was greatest in mid nineteen sixties. Additional fallout from the accident at the Chernobyl Nuclear Power Plant was relatively small. The study gave preliminary information on the spatial variation in ¹³⁷ Cs deposition in Iceland, especially in areas used for agriculture. The objectives of the study were (1) to measure the spatial variation of radiocaesium inventories in soils in Iceland and (2) to compare the results with different approaches to predicting ¹³⁷ Cs contents in soil. This quantification is a necessary first step in an evaluation of vulnerability to radiocaesium deposition in Iceland. It is anticipated that Icelandic soils could be highly vulnerable to radiocaesium due to their volcanic nature and consequent lack of illitic minerals, as has been suggested by initial chemical studies on the properties of soils in the Nordic countries. (ln)

[en] Countermeasures have been effectively employed within intensive agricultural systems in areas of the Former Soviet Union (FSU) affected by the Chernobyl accident. However, ingestion doses continue to be elevated in some areas as a result of few foodstuffs which are collected from the wild or produced by the household. Forest fungi and berries, and milk from privately owned cattle are the most notable contributors to ¹³⁷Cs intakes amongst these foodstuffs. In this paper we consider advice which would help affected populations to both understand the importance of these exposure routes and to reduce their exposure. In addition to the potential radiological benefits, self-help schemes are highly cost-effective and likely to have a positive psychological influence on populations living within contaminated areas of the FSU. Evidence to suggest that the transfer of radiocaesium to cow milk is considerably higher in the FSU than within western Europe and North America is discussed