Food chains and model development, radionuclide - Project topic/title
	Radionuclide uptake and transfer in pelagic food chains of the Barents Sea and resulting doses to man and biota.
Co-ordinating institution
	Norwegian Radiation Protection Authority
Final report
	Justin Brown et. al:  Radionuclide uptake and transfer in pelagic food chains of the Barents Sea and resulting doses to man and biota.
Summary and results
	Summary   Arctic seas receive inputs of radionuclides from a number of sources including global fallout, discharges from western European reprocessing plants and the Chernobyl accident, amongst others. These radionuclides are transported by prevailing marine currents and assimilated to varying degrees by biota in accordance with the biogeochemical behaviour of the radionuclide in question. Traditional impact assessments have been firmly focussed on the derivation of doses to man and have therefore considered the uptake and distribution in food-chains that are relevant for human consumption. In many cases, the available data are insufficient to allow a mechanistic understanding of uptake and transfer of radionuclides to be made or to create the basis for robust environmental impact assessments to be conducted. Further insight into the uptake of a suite of radionuclides, including 137Cs, 90Sr, 239,240Pu, 241Am and 99Tc by biota belonging to Arctic marine foodchains was clearly required.     The objectives of this project were to : To identify and quantify the key parameters that control uptake and accumulation of anthropogenic radionuclides in marine biota To collate information relating to transfer (fluxes) of radionuclides though marine food-webs To develop new models (doses to biota and human radiological assessment) using the information from field and laboratory studies. Field-work was conducted in January-February 1999 which involved the collection of seawater, sediments and biota samples. Additional fieldwork has involved the sampling of seaweed at several locations along the Norwegian coast. Laboratory work has been performed to consider the sorption kinetics of Pu and the uptake and depuration of 134Cs and 60Co by common mussels (Mytilus edulis) from (a) ultrafiltered seawater and (b) sediments. The uptake of 137 and 57Co by phytoplankton was also studied in the laboratory. Analyses of samples from field and laboratory experiment have been performed using standard radiometric techniques and the data derived from this work have been discussed in the context of radionuclide biogeochemical behaviour and transfer of radionuclides within marine foodchains. Results from the field studies and earlier work (a data collation exercise forms part of the report) have been used in calculating doses to man and biota in Norwegian coastal environments. Scenarios (e.g. those discussed within the framework of the International Arctic Seas Assessment Project) have been used to predict potential doses to man and the "environment" following accidental releases of radionuclides. The vulnerability of the marine ecosystem, as currently defined within the field of radioecology, is considered in the context of the contamination of Arctic marine environments by radioactivity.       Scientific results   The main results from this project are summarised below :     (a) The concentration of radionuclides in marine organisms in the Barents Sea (based on 1999 data) is generally low, and seems (in most cases) to be in proportion with surrounding seawater concentrations. Generally the field-based Kd values agree well with other previous studies from the area and emphasize the importance of site-specific data, as the present results are lower than the generic IAEA (1985) data. The laboratory based tracer experiments show that the sorption of Pu(V,VI) to sediments is a time dependent process, and several months are needed to reach semi-equilibrium.     (b) Kinetic tracer experiments are useful to estimate the bio-concentration factors BCFs, and the results are in agreement with field derived BCF ranges published in IAEA (1985) and Fisher et al. (1999). The uptake experiments of low molecular mass (LMM) radionuclides in Mytilus edulis showed that the uptake rate coefficients are higher for Co than for Cs, and the calculated BCFs increased accordingly. The depuration of the tracers in the mussels could be described by multi-exponential functions, and a two-compartment model was used to estimate the uptake and depuration kinetics of the contaminants within the mussels. Laboratory experiments were also well suited for estimating the assimilation efficiencies (AEs) for the tracers studied, used to assess the retention of resuspended contaminated particles in mussels in a model based on toxicokinetic considerations (Børretzen, 2001). Furthermore the results show that resuspended contaminated sediments may represent an important pathway for radionuclides such as Co and Cs to the filter feeding Mytilus edulis.     (c) Bioaccumulation of 137Cs is not observed in growing cells of five phytoplankton species representing the Barents Sea phytoplankton community. Bioaccumulation is, however, observed in organisms representing higher levels in the Barents Sea food webs. Results indicate a direct uptake of 137Cs from seawater by zooplankton consumers, e.g. herring, herring larvae, capelin and saithe fry. Robust evidence to support the hypothesis that 137Cs is significantly biomagnified through the Barents Sea food web has not been found.     (d) Dose rates for biota in the Barents Sea (based on shrimp data for 1999) are extremely low amounting to approximately 5 mGy/year. A large proportion of this dose is derived from external irradiation of the biota from 137Cs in bottom water and sediments. In relation to possible release scenarios in the Arctic (IASAP scenario), dose rates for most biota are predicted to be below a level where significant effects on populations of wild organisms would be observable. However, conclusions are highly tentative and further dose-effects data are required.     (e) The consumption of seafood harvested in the Barents Sea forms dose rates to the world population of about 2.7-4.5 manSv/year (for the years with the average and maximal harvest of seafood). The contributions of different seafood items to dose are estimated as follows: fish - 92.6%; crustaceans - 4%; seaweeds - 1.7%; molluscs- 1.4%; sea mammals-about 0.3%. The contribution of 137Cs to the annual collective dose is about 90%, 90Sr and 239,240Pu - 5% each. The current collective dose rate from consumption of seafood harvested in the Kara Sea is estimated at about 0.03 manSv/year and can be considered insignificant.         Relevance to Monitoring   Conventionally, monitoring programmes include simultaneous sampling of water, sediment and biota, which should clearly also be performed here. Such an approach provides a good overview of the environmental contamination and the chance to extract refined and site specific parameter values that can benefit consequence assessment models.   On the basis of the present project results and on the international work presently carried out concerning protection of species other than man for harmful effects of radiation, special emphasis should be put on the sampling of biota. The activity concentrations of radionuclides are essential in the evaluation of radiation doses to both humans and other living species. For humans, a dominating exposure pathway will be consumption of marine foodstuffs. Collective doses from fish consumption dominates today, but different contamination scenarios, resource situation and eating habits may change this conclusion in future or longer time-scale assessments. For the purpose of monitoring doses to humans, sampling should include fish, crustaceans, molluscs, seaweeds and possibly sea mammals that are the most relevant for human consumption today, or which have the potential to become important in the future. Measurements should be performed on the edible fractions of the biota samples.   As a new framework for protection of biota from adverse effects of radiation is expected to emerge in the next few years, and a future monitoring programme must be designed accordingly. Information on activity concentrations in whole body/muscle of organisms are suitable for dose calculation in line with current monitoring practice but more detailed information may be required, whereby selected organs within the organisms are analysed to allow more robust whole body dose rates to be determined. The relationship between radiation dose and possible effects is a subject of further research. A suitable approach may be the identification of suitable "reference" organisms that can be selected to represent the larger ecosystem. Any future monitoring work will need to integrate the recommendations made by ongoing research projects that aim to identify such biota types in the marine environment. In addition the compilation of data pertaining to dose effects relationships for selected reference species will allow a transparent assessment to be made of the environmental impact of radioactivity.
Original project description
	Introduction Very few studies relating to the transfer of radionuclides through marine ecosystems and consequences to Man have been conducted in Arctic seas. Important sources of information that are currently available, include the studies of the Joint Norwegian-Russian Expert Group for the investigation of radioactive contamination in Northern areas (Strand et al., 1994; Salbu et al., 1995a, Salbu et al., 1995b., Nikitin et al., 1995; Strand et al., 1997), the Arctic monitoring and assessment Programme - AMAP (Strand et al., 1996; Strand et al., 1997) and the work of the International Atomic Energy Agency - IAEA (e.g. Baxter et al., 1998). The Norwegian Radiation Protection Authority (NRPA), The Institute of Marine Research (IMR), the Institute for Energy Technology (IFE) and the Agricultural University (AU) have all been involved in the Joint Norwegian-Russian Expert Group studies and the NRPA is currently co-ordinating the activities of the radioactivity expert Group in AMAP. In spite of this work, a detailed knowledge of uptake mechanisms, such as changes in concentration factors (CFs) over time and the variability between and within species in these extreme Arctic environments is entirely absent. Most radiological assessment models that are currently used to calculate doses to man from the marine environment (e.g. Nielsen et al., 1995) use generically-derived factors (e.g. IAEA, 1985) which are by definition non-specific. For example IAEA (1985) provides radionuclide CF information for the broad categories of «fish» and «crustacea». Clearly there is room for improvement for the sake of more accurate impact assessments. Little work has been undertaken in relation to the consequences of radioactive contamination for biota. The emphasis in radiological protection has traditionally been on the consequences to human health from exposure to radiation. Basic models exist (Amiro, 1997) in relation to biota dose calculations but there is great scope for improvement and development. It should be mentioned that this theme has currently been adopted by the International Union of Radioecologists with a view to creating new guidelines and a regulatory framework. Furthermore, IAEA will implement a concerted action on the speciation of radionuclides and the impact of hot particles in 1999. An opportunity has therefore arisen for this project to be an important factor in these processes, providing invaluable information and raising the profile of the work on an international stage. In terms of the biological effects on biota for a given dose, some information is available in the open literature (Rose, 1992; Polikarpov, 1998). For example the lowest chronic exposure that has been documented to have caused death in mammalia is 3.6 Gy/year and the lowest chronic exposure that has produced detectable changes in behaviour and development (in this case for planarium worms and mud snails) was 10-2 Gy/year. To put this into some kind of context, doses of 2.3 x 10-5 Gy/year arising from 99Tc alone for Fucus serratus in Oslofjord have recently been calculated (Brown and Strand, 1998). This level of activity is clearly well below the level where any biological effects may be observed. However, it should be noted that for much more contaminated sites, close to dumped nuclear objects or discharge points for example, the combined effect of a number radionuclides may be significant. In addition the levels of radionuclides in the environment that might be expected after an accidental nuclear release can also be significant. For example, such high releases of radioactivity to the environment were observed in the early 1950s around Mayak PA (Southern Urals in Russia) with resulting doses to fish of up to 2 Gy d-1. These doses were responsible for the mass death of fish in the upper part of the Techa River (Kryshev & Sazykina, 1998). At comparatively much lower contamination levels, dose rates up to 0.045 Gy per annum can be calculated for the green gland of lobsters in the Irish Sea (Brown & Strand, 1998) based on data in Busby et al. (1997). This may be at a level where behavioural or developmental effects can be observed for animalia as discussed above. A detailed examination of biological effects will not form part of this proposal but, of course, our current knowledge in relation to this subject will be integrated into the interpretation of our results.   Research Strategy Future monitoring programmes for anthropogenic radionuclides in the Barents Sea should be based on integrated assessments of the risks associated with both present contamination and potential releases of radionuclides into the Arctic Ocean. Closely related to this is the vulnerability of the marine ecosystems. The identification of vulnerable areas, will allow financial resources to be used wisely in choosing locations for long-term monitoring programmes. The concept of vulnerability, at least in the terrestrial environment, has been the subject of some attention (Howard & Strand, 1997) and has recently become the subject of an European Commission Concerted Action. The research strategy can be simply summarised in three steps. Step 1 requires the collection of new information where current data sets are of poor quality or in some cases entirely missing. Step 2 requires the integration of these data into radiological assessment models and Step 3 requires the use of models and new knowledge to identify vulnerable areas and determine the best strategy for future monitoring programmes. Several areas have been identified as requiring some attention in the development of more realistic/sophisticated radiological assessment models (doses to man and biota) and in assessments of vulnerability : Information about processes that control uptake and accumulation of radionuclides in marine food-webs Data relating to the quantities of phytoplankton, zooplankton, krill, shrimp and fish that are produced in northern seas allowing the calculation of activity fluxes, i.e. the total uptake and transfer of radionuclides in the Arctic marine food chains. Information about radionuclide activity levels in certain species in the Arctic marine food chain New, sophisticated models will allow much more accurate predictions of impact after potential releases of radionuclides. The fact that geochemical and sedimentological processes will also play an important role in influencing the behaviour and fate of radionuclides before assimilation by biota and transfer to Man, necessitates a close link between the «effect» programme and the «transport» programme.   Aim and Objectives The main aim of the project is to obtain information about the vulnerability of the Arctic marine environment in relation to different radionuclide releases scenarios and to make recommendations for future monitoring programmes. A certain knowledge of the controlling processes on uptake already exists. This project aims to build on this understanding and to focus on factors considered to be relevant for Arctic environments. This will be achieved through the following objectives : To identify and quantify the key parameters that control uptake and accumulation of anthropogenic radionuclides in marine biota through field investigations and laboratory experiments. To collate information relating to fluxes of radionuclides though marine food-webs using production data To develop new models (doses to biota and human radiological assessment) using the information from field and laboratory studies.   Project description The project will be coordinated by the Norwegian Radiation Protection Authority (NRPA) in collaboration with the Institute of Marine Research (IMR), The Agricultural University of Norway (AUN) and The Institute of Energy Technology (IFE). The project will also involve the participation of Russian Scientists - Roshydromet «TYPHOON». The project is organised into 5 work packages. Project coordinator : Dr. Justin Brown, NRPA Work Package 1 :Biological uptake mechanisms and CF variations between biological species Work Package leader : Professor Brit Salbu, AUN Emphasis for this work-package will be characterising the variability of the concentration factor within the same species of fish. Several species of fish will be studied, including cod (Gadus morhua), capelin (Mallotus villosus) and haddock (Melanogrammus aeglefinus) and benthic organisms (e.g. blue mussels). The investigation will include both controlled uptake experiments (laboratory) and analysis of fish and sea water sampled in the Norwegian Sea and the Barents Sea. The following research areas will be investigated : Uptake mechanisms and the influence of physico-chemical form of radionuclides on uptake. This may include size fractionation studies on seawater. Stable analogues for the radionuclides under consideration will be studied in order to provide more information in relation to the kinetics of isotopic exchange Distribution of stable analogues/radionuclides between organs will be studied. The following radionuclides will form the focus of the work - 137Cs, 99Tc, 90Sr, 239,240Pu, 238Pu and 241Am. These radionuclides can be measured by standard low-level radiometric techniques but other low-level techniques (e.g. Inductively coupled plasma mass spectrometry - ICP-MS and accelerated mass spectrometry - AMS) will also form an important part of analysis work. AUN will take the lead role in this work package although analyses and other work will be conducted at NRPA, IFE and IMR. Timetable for tasks in Work-Package 1 Task Partner 1st year 2nd year Laboratory uptake experiments AUN, IMR x x x x         Collection of samples/fieldwork ALL x x x x         Gamma analyses ALL   x x x x       90Sr analyses IFE, AUN   x x x x       99Tc analyses NRPA, AUN   x x x x       Actinide analyses AUN, NRPA,IFE   x x x x       Data processing ALL x x x x x x x   Report ALL           x x   The work for this work package needs to be completed by the 3rd quarter of the 2nd year (18 months into the project) to allow inclusion of these data into the modelling and vulnerability work packages.   Work Package 2 : Transfer of radionuclides in marine (mainly pelagic) food chains Work Package leaders : Dr. Lars Føyn in cooperation with Dr. Per Varskog Detailed investigations of important food chains for fish species will be undertaken. The most important species of fish in the Barents Sea is cod (Gadus Morhua). The diet of the cod varies from one year to the next as shown by the annual studies of IMR in which the total consumption of various prey species is calculated based on studies of the stomach content in fish from the Barents Sea. The most important prey species are usually krill (Euphausiacea), cod, capelin (Mallotus villosus), amphipods, shrimp (pandalus borealis) and several other species. IMR will continue to collect samples of these species together with samples of phytoplankton and zooplankton (Calanus finmarchicus) from the Barents Sea. Selected radionuclides, e.g. 137Cs,90Sr, 99Tc, 239,240Pu, 238Pu and 241Am, will be determined and calculations will be made in relation to the importance of selected prey species in the diet of cod and concentration factors for these species. In order to provide a complete picture of the marine environment shellfish will also be studied, although in less detail. At very least, actinide (239,240Pu, 238Pu and 241Am) analyses will be undertaken for plankton and shell fish. These taxonomical groups are known to concentrate actinides in aquatic environments whereas the transfer to higher trophic levels does not occur to a high degree (Wahlgren & Marshall, 1975). With this in mind it is important to understand the uptake to these lower trophic levels as they will form the critical biological compartment after a radionuclide release. The analyses of 99Tc will be conducted specifically for brown seaweeds and crustacea which are known to concentrate this radionuclide to a high degree (Busby et al., 1997; Dahgaard et al., 1997; Christensen & Strålberg, E., 1998; Brown et al., in press) In summary, levels of radionuclides (137Cs, 90Sr, 99Tc, 239,240Pu, 238Pu and 241Am) in selected biological compartments will be determined and used to investigate the transfer and fluxes of radionuclides through marine food chains. IMR, in cooperation with IFE, will take the lead role in this work package with their expertise in the sampling and study of food-chains. Their work will be supported by the analytical efforts of NRPA and AUN.   Timetable for tasks in Work-Package 2 Task Partner 1st year 2nd year Sample collection/field work IMR/IFE x x x x         Gamma analyses ALL   x x x x       99Tc analyses NRPA/AUN   x x x x       90Sr analyses IFE/AUN   x x x x       Actinide analyses NRPA/AUN/IFE   x x x x       Data processing ALL x x x x x x     Report ALL           x     The work for this work package needs to be completed by the 2nd quarter of the 2nd year (18 months into the project) to allow inclusion of these data into the modelling and vulnerability work packages.   Work Package 3 : Doses to biota Work Package leader : Dr. I Kryshev, TYPHOON The main objectives of this work package will be to Develop the concept of doses to biota, Modify existing models to quantify doses to biota Calculate doses to biota based on real (monitoring) data and data derived from the modelling of released scenarios. Scientists at TYPHOON, Russia are currently working with the modelling of doses to biota (see Kryshev et al., 1997; Kryshev et al., 1998; Kryshev & Sazykina, 1998). These models will be adapted specifically for use in the northern seas using input data from this project (Work Package 1 and 2) and historical data archived in Russian institutes. The philosophy of dosimetry for biota will be developed further in conjunction with the International Union of Radioecologists. This project will benefit greatly from this interaction with the leading scientist in the field of radioecology. The modelling of doses to biota (both pelagic and benthic), will constitute an important tool in the assessment of the impact of radionuclides released into the environment. Input data on the concentrations of radionuclides in biota and abiotic marine environment (water, sediments) are required for the calculation of doses to biota. This will be derived either directly from analyses of the monitoring data on the marine ecosystems contamination, or by modelling the time-dependent transport and fate of radionuclides in marine ecosystems under different release scenarios. Clearly data from work packages 1&2 will form important input data sets here. Dose calculations will be performed for the most important representatives of the marine ecosystems of the Norwegian and Barents Seas, such as fish and fish eggs (cod, haddock, capelin, plaice and others); dominant species of phytoplankton, zooplankton, molluscs, macroalgae, and sea mammals. Assessment of doses to the marine organisms will be made in accordance with the IAEA recommendations (IAEA, 1976; IAEA, 1979; IAEA, 1988), using the detailed computerised methodology, described in publications from TYPHOON (Kryshev & Sazykina, 1986; Kryshev, 1995; Kryshev & Sazykina 1995a; Kryshev & Sazykina, 1995b; Kryshev & Sazykina, 1995c; Kryshev & Sazykina, 1996a; Kryshev & Sazykina, 1996b; Sazykina & Kryshev, 1996; Kryshev, 1996; Kryshev & Sazykina, 1998; Sazykina et al., 1998). In the procedure of dose assessment the following species-specific information is taken into consideration: geometrical parameters of organisms , concentrations of radioactive and stable analogous elements in different tissues and organs, behavioral and feeding habits; position of species in the food webs. The geometrical shapes of organisms are approximated by appropriate geometrical models. Fish, mollusks, large zooplankton and sea mammals are represented as cylinders or ellipsoids of different sizes; phytoplankton, fish eggs and small zooplankton - as spheres of appropriate radiuses; macroalgae are approximated either by spheres or with a layer (plate) of finite thickness. In the marine environment, doses to biota will originate from external irradiation owing to the presence of radionuclides in the water column and bottom sediments, and from internal irradiation owing to the uptake ans assimilation of radionuclides by biota as discussed below: (1) External irradiation. The sources of external irradiation of marine biota are the following: irradiation from contaminated water and bottom sediments; irradiation from contaminated overgrowings of macroalgaes; irradiation from radionuclides adsorbed on the surfaces of organisms. In the assessment of external dose, water is considered as an infinite source with uniformly distributed radionuclides. The bottom sediments are represented as a layer of finite thickness with uniformly or non-uniformly distributed activity of radionuclides. The computerized dose assessment procedure will provide the calculated values of the dose conversion factors for each type of biota from the Arctic Seas from different radionuclides. For large organisms the predominant external irradiation pathway will be from gamma-emitters, and to a lesser extent from beta-particles. For small organisms (phytoplankton, small zooplankton, fish eggs) , the doses from alpha- and beta particles adsorbed on their surfaces may be important in the external dosimetry. (2) Internal irradiation. The internal dose rates to marine biota are resulted mainly from radionuclides incorporated within organisms. A first step in assessment of internal doses is the determination of radionuclides activity in the tissues /organs of organisms. This can be derived either from monitoring data, or from special radioecological models with consideration of the following processes: the uptake of radionuclides with food, bioassimilation, growth, and excretion. The data from the work packages 1,2 will be used for calculation the dynamics of the radionuclides activity within the growing fish in the Arctic Seas. To reconstruct or predict radioecological processes in marine ecosystem a dynamic radioecological model ECOMOD-W may be used. The model consists of three interrelated sequentally running computer programs (Kryshev & Sazykina,1986; Sazykina & Kryshev, 1996) : block "ECOSYSTEM" (model of an aquatic ecosystem) - block "RADIONUCLIDE DISTRIBUTION" (calculation of the dynamical values of radionuclides activity in each type of biota) - block "DOSE ASSESSMENT" (dose-to-biota assessment). The dose assessment to the biota in the Arctic Seas is a more complicated task as compared with the assessments made for biota of temperate climate. Because of severe climatic conditions in the Arctic Seas, many species of fish, zooplankton and sea mammals exhibit the long-distance feeding, wintering and spawning migrations within the year. Therefore, the equilibrium values of concentration factors (CFs) may be derived only for sedentary organisms (molluscs, etc.), however for most important species of fish, large zooplankton and sea mammals the equilibrium values of CFs is probably not established during the period of residence of a population in any particular marine sub-area. The computerised dose assessment procedure will provide the calculated values of the internal dose rates for each type of biota from the Arctic Seas. The dose assessment provides the calculated values of dose rates to a marine organism from each individual radionuclide, also the dose rate from combined action of all radionuclides, as well as the values of dose accumulated for certain periods of life cycle. Quality factors should be established to account the higher biological effectiveness of alpha-emitters. The further development of dosimetric models will include the consideration of non-homogeneous distribution of radionuclides within the marine organisms. The main objective of this work package will be to develop the concept of doses to arctic marine biota , refine calculations and finally to calculate doses to biota based on real (monitoring) data and data derived from the modelling of release scenarios. TYPHOON will take the lead role for this work package. Timetable for tasks in Work-Package 3 Task Partner 1st year 2nd year Collation of data TYPHOON x x             Development of dosimetric model TYPHOON/NRPA x x x x x x     Model calculations TYPHOON/NRPA         x x x   Report TYPHOON/NRPA       x     x   Two report will be produced, one at the end of the first year and one towards the end of the project.   Work Package 4 : Doses to man Work Package leaders : Dr. Mikhail Iosjpe, NRPA + Dr. I. Kryshev, TYPHOON The output from the modelling of various contamination scenarios will be ultimately used to calculate radiation doses to man. This can take the form of calculating either the effective dose commitment (doses weighted according to sensitivity of body organs to ionising radiation and integrated over a specified time period - Sv) or collective effective doses (The average dose to an exposed population or group multiplied by the number of people in the group - ManSv). Both approaches may be useful in this study. In certain cases it may be informative to consider 'critical groups' to release scenarios, i.e. individuals that receive the highest doses relative to the population as a whole due to their eating habits and other behavioural patterns. In other cases the consideration of the population as a whole may provide us with a more suitable assessment. The doses received by individuals, groups of individual or populations relates directly to the risk of mortality. In this way the impact of a given discharge scenario can be quantitatively compared with other scenarios in terms of risk to man. The objective of this work package will be to calculate doses to Man based on real (monitoring) data and predicted data derived from the modelling of release scenarios. Scientists at NRPA are currently working with the calculation of collective doses to Man based on traditional box modelling techniques (Nielsen et al., 1995; Nielsen et al., 1997). The general assumption for box modelling about instantaneous mixing in each box, leads in practical calculations to instantaneous mixing in the whole of oceanic space. To improve this model, a box model which still describes a box structure with uniform mixing in all boxes, but also includes dispersion of radionuclides during time has been created (Iosjpe et al., 1997; Iosjpe & Strand, 1998). This gives a better and more realistic/physical approach compared to traditional techniques. The present version of the model keeps the options for global modelling, but also has elements of more local/regional models. The NRPA model will be used to make radiological assessments over large distances (> 1000 km) and long time-scales (centuries or millenniums). The radiological assessment of discharges of radionuclides to the marine environment will integrate the processes of transport (from the transport programme) and the new data on transfer and uptake of radionuclides collected during the present project. The output from the modelling of various contamination scenarios will also be used to calculate radiation doses and risk to man by scientists at TYPHOON. The individual annual doses to humans from the Barents Sea region will be calculated (Sv/year), as well as collective dose rates to populations (PersonSv/year). Doses integrated over a specified time period will be calculated for selected release scenarios. The assessment of doses to man is made in accordance with the ICRP and IAEA recommendations. When assessing the dose and radiation risk to man, the following pathways of exposure are considered: consumption of seafood (commercial species of fish, shrimps, molluscs, sea mammals, sea-weeds), inhalation of sea spray and suspended matter in the coastal zones, external radiation from sea water and coastal soil. Assessment of individual dose rates from seafood consumption will be made for representatives of two groups: average seafood consumers and high-rate seafood consumers. Critical groups of humans will be considered for contamination scenarios, i.e. groups of humans that received the highest individual doses relative to the average population due to their eating habits and other behavioural patterns. The doses to man will be calculated using the data on seafood consumption and its contamination with radionuclides. The detailed statistical data on the seafood consumption and occupational behaviour of humans in the Barents Sea region will be collated and used in the calculation of doses to man. The data on radionuclides content in each type of seafood will be either derived from monitoring measurements, or will be calculated on the basis of release scenarios. The doses received by individuals, groups of individuals or populations relates directly to the risk of mortality. The risk assessment to man will be made in accordance with the ICRP recommendations. The impact of a given contamination scenario will be quantitatively compared with other scenarios in terms of risk to man. The objective of this work package will be to calculate doses to man based on real (monitoring) data and predicted data derived from the modelling of release scenarios. NRPA and TYPHOON will take the lead role for this work package. Task Partner 1st year 2nd year Collation of data TYPHOON x x             Model development and calculations - collective doses TYPHOON/NRPA x x x x x x     Model development and calculations - Critical Group TYPHOON/NRPA x x x x x x     Scientific Report TYPHOON/NRPA             x     Work Package 5: Vulnerability Work Package Leader : Dr. Justin Brown, NRPA The vulnerability of the marine environment to anthropogenic radionuclides may be described by the degree (or sum) of harmful effects that follows a given radionuclide release or a given degree of contamination. The most obvious potentially harmful effects are the possible health, environmental and economic consequences. The vulnerability of the marine environment will depend on a number of factors that may be specific to a certain area or ecosystem. Criteria for the assessment of vulnerability can be related to radiation doses to humans, both critical groups and (committed) collective doses, estimated radiation doses to various marine organisms, and economic effects due to unacceptable levels of radionuclides in fish and other marine products. The key objective of this work-package will be to summarise the results from the other 4 workpackages and use these data to identify vulnerable areas. The possible problems for the fishing industry caused by the potential radionuclide content in marine products will be assessed and recommendations for future monitoring programme presented. NRPA will take the lead role for this work package. Task Partner 1st year 2nd year Development of guidelines for vulnerability assessment NRPA x x x x x x     Recommendations for future monitoring programmes ALL               x Collation/synthesis of data from other work packages ALL         x x x x Summary report NRPA             x x   The summary Report will form the main deliverable of the whole project. This report will provide an overview of the project. For more detailed information, the individual work-packages will need to be consulted.   Summary The present project package consists of five work packages on the transfer of radionuclides in pelagic food chains of the Barents Sea and resulting radiation doses to Man and biota. Field investigations and laboratory experiments will be used to obtain more information on processes and parameters controlling uptake and transfer of radionuclides. This new information, together with existing knowledge, will allow form the basis for the better predictions of development of new radioecological models for this the biogeochemical behaviour and fate of radionuclides transfer to be made. Radiation doses to the organisms in the food chain will be calculated using suitable dosimetric models, taking into account the doses received from seawater, sediment and assimilated incorporated radionuclides. Model calculations will be compared with simplified methods for environmental dose estimates. Models will also be used for calculating resulting radiation doses to humans from the consumption of fish. The models will be a tool for predicting consequences from potential future contamination of the Barents Sea. In addition, by also implementing results from the transport programme, the degree of harm, or vulnerability related to contamination from, that relates to radionuclides in economically and ecologically important pelagic food- chains under various release scenarios can be evaluated. This information will be important for the planning of a future monitoring programme in the Barents Sea.   Participation The project will be coordinated by the Norwegian Radiation Protection Authority (NRPA). Institute of Marine Research (IMR), Institute for Energy Technology (IFE) and Agricultural University of Norway (AUN) will be partners in Norway. Russian partners will include Typhoon.   Budget The total budget for the project is 1.4 million NOK to be separated as listed : Work package 1: Total budget: NOK 890 000,-. NOK 470 000,- is applied for from the Effects Programme, while NOK 420 000 is covered by the participating institutions.  Work package 2: Total budget: NOK 825 000,-. NOK 470 000,- is applied for from the Effects Programme, while NOK 355 000 is covered by the participating institutions.  Work package 3: Doses to biota Total budget: NOK 250 000,-. NOK 200 000,- is applied for from the Effects Programme, while NOK 50 000 is covered by the participating institutions.  Work package 4: Doses to man Total budget: NOK 250 000,-. NOK 200 000,- is applied for from the Effects Programme, while NOK 50 000 is covered by the participating institutions.  Work package 5: Vulnerability Total budget: NOK 60 000,-. The entire sum is applied for from the Effects Programme. References Amiro, B.D. (1997). Radiological dose conversion factors for generic non-human biota used for screening potential ecological impacts. Journal of Environmental Radioactivity, 35, pp.37-51. Brown, J.E., Kolstad, A.L., Brungot, A.L., Lind, B., Rudjord, A.L., Strand, P. & Føyn L. (in press).Levels of 99Tc in biota and sea water samples from Norwegian coastal waters and adjacent seas. 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