[en] Although the safety of repositories for radioactive waste should not depend of active controls such as monitoring, several control measures may be required for a variety of societal reasons. It is possible that the reporting of environmental monitoring to international treaties and conventions, already in place today, may be of value in meeting those requirements. To prepare for passive institutional control includes taking measures today that may be of use for future institutional control, including the possibility that future societies may initiate or renew active control measures. Passive institutional control may be of use to prevent or reduce the likelihood of human intrusion, to allow for remedial action, or to serve as a source of information in future societies, in the form of accurate historical documents. In the process of reporting within international conventions, including the most important reporting within the so-called Waste Convention, a large body of information will be built up by a process already in place today. This information is in itself a source for passive institutional control. (author)

[en] Currently, there is no established methodology to estimate radiation doses to non-human biota. Therefore, in this study, various dose models were used to estimate radiation doses to moor frogs (Rana arvalis) in a wetland ecosystem contaminated with ¹³⁷Cs. External dose estimations were based on activity concentrations of ¹³⁷Cs in soil and water, considering changes in habitat over a life-cycle. Internal doses were calculated from the activity concentrations of ¹³⁷Cs measured in moor frogs. Depending on the dose model used, the results varied substantially. External dose rates ranged from 21 to 160 mGy/y, and internal dose rates varied between 1 and 14 mGy/y. Maximum total dose rates to frogs were below the expected safe level for terrestrial populations, but close to the suggested critical dose rate for amphibians. The results show that realistic assumptions in dose models are particularly important at high levels of contamination

[en] Wetlands function as nurseries and feeding areas for both terrestrial and aquatic species and are habitats for many endangered species such as frogs, salamanders and snakes. Wetlands alter the hydrology of streams and rivers, enhance sediment deposition and work as a filter to coastal waters retaining nutrients as well as contaminants. Due to the lack of easily identifiable direct pathways to humans wetland ecosystems have generally been neglected within radioecological research. There is a large diversity of wetlands and some of them can accumulate and function as sinks for radionuclides. In Sweden wetlands are among the ecosystems where the highest activity concentrations have accumulated after the Chernobyl accident. This paper summarizes factors that are important to the accumulation of radionuclides in wetlands. As an example, one wetland ecosystem in Sweden contaminated by ¹³⁷Cs due to the Chernobyl accident will be described in more detail. The average activity concentration in this wetland is 1.1 MBq/m², i.e. 10 times higher than in the surrounding areas. Soil and sediment samples were collected and the ¹³⁷Cs activity concentrations were measured. A budget calculation of ¹³⁷Cs in the wetland area was conducted, indicating that the accumulation of ¹³⁷Cs is still ongoing seventeen years after the accident. High activity concentrations are likely to remain in this ecosystem for a long time, resulting in long-term exposure for organisms living there. The maximum external ¹³⁷Cs dose rate to frogs was estimated to 96 mGy/year. Hence, identification and consideration of wetlands that accumulate radionuclides to a high extent are important in radioecological risk assessments for the protection of plants and animals from ionizing radiation. (author)

[en] Internal and external radiation doses to frogs living in a wetland ecosystem contaminated with ¹³⁷Cs were estimated. The external doses were calculated from measured concentrations of ¹³⁷Cs in soil and in water taking into account changes in the habitat during the frogs' life cycle. The internal dose was estimated from measured concentrations of ¹³⁷Cs in living frogs (Rana arvalis) using a whole-body counter. The average inventory of ¹³⁷Cs in the soil was approximately 1000 kBq/m² of which 86-99 % was found in the top 12 cm. The concentrations of ¹³⁷Cs in frogs varied between 560 and 3450 Bq/kg ww. The estimated external dose rate was between 21 and 160 mGy/y, while the internal dose of beta and gamma was only between 1 and 6.2 mGy/y. The estimated total dose rate to frogs from ¹³⁷Cs was below the expected safe level for terrestrial populations but close to the critical dose rate for amphibians suggested in the literature. Therefore, the radiation risk to frogs from radiocaesium in the study area may be one more stressor for an endangered group of animals in this ecosystem. (author)

[en] After the Chernobyl accident, high activity concentrations of ¹³⁷Cs (>1 MBq m^-2) were detected in a riparian swamp in the central-eastern part of Sweden. The objective of this study was to clarify the redistribution processes behind the accumulation of ¹³⁷Cs in the wetland. A mass balance budget of ¹³⁷Cs was calculated based on soil and sediment samples and reports in the literature. Results showed that accumulation occurred over several years. Of all the ¹³⁷Cs activity discharged between 1986 and 2002 from the upstream lake, 29% was estimated to be retained in the wetland. In 2003, measurements showed that 17 kBq m^-2 sedimented on the stream banks of the wetland. Continuing overbank sedimentation by spring flooding prolongs the time that the wetland will contain high activity concentrations of ¹³⁷Cs. Consequently, organisms living in wetlands serving as sinks for ¹³⁷Cs may become exposed over long time periods to high activity concentrations