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G Pröhl

Publications and source records attributed to G Pröhl.

At least 19 recordsLinked to original sources
PubMed2006

Ecological half-lives of 90Sr and 137Cs in terrestrial and aquatic ecosystems.

This paper describes the long-term behaviour of (90)Sr and (137)Cs in foods, feeds and a variety of environmental media. The long-term behaviour is quantified by means of the ecological half-life which integrates all processes that cause a decrease of activity in a given medium such as leaching, fixation and erosion. A large number of long-term time series of concentrations of radiocaesium and radiostrontium in these media have been identified and re-evaluated using a standardised statistical procedure to establish reference data sets of ecological half-lives. By example of undisturbed soils and marine water bodies it is shown that the ecological half-life concept is questionable if the distribution of the radionuclide of interest within the medium studied is non-uniform and if mixing and transport processes within this medium, therefore, are of considerable importance during the time period of observation.

Animals↗
PubMed2006

A practical method for assessment of dose conversion coefficients for aquatic biota.

Radiological impact assessment for flora and fauna requires adequate dosimetric data. Due to the variability of habitats, shapes, and masses of the non-human biota, assessment of doses is a challenging task. External and internal dose conversion coefficients for photons and electrons have been systematically calculated by Monte Carlo methods for spherical and ellipsoidal shapes in water medium. An interpolation method has been developed to approximate absorbed fractions for elliptical shape organisms from absorbed fractions for spherical shapes with reasonable accuracy. The method allows an evaluation of dose conversion coefficients for arbitrary ellipsoids for photon and electron sources with energies from 10 keV to 5 MeV, and for organism masses in the range from 10(-6) to 10(3) kg. As an example of the application of the method, a set of dose coefficients for aquatic organisms discussed as reference animals and plants in a draft of an up-coming publication of the International Commission on Radiological Protection has been determined.

Animals↗
PubMed2006

Application of a generic biosphere model for dose assessments to five European sites.

The BIOMOSA (BIOsphere MOdels for Safety Assessment of radioactive waste disposal) project was part of the EC fifth framework research programme. The main goal of this project was to improve the scientific basis for the application of biosphere models in the framework of long-term safety studies of radioactive waste disposal facilities and to enhance the confidence in using biosphere models for performance assessments. The study focused on the development and application of a generic biosphere tool BIOGEM (BIOsphere GEneric Model) using the IAEA BIOMASS reference biosphere methodology, and the comparison between BIOGEM and five site-specific biosphere models. The site-specific models and the generic model were applied to five typical locations in Europe, resulting in estimates of the annual effective individual doses to the critical groups and the ranking of the importance of the exposure pathways for each of the sites. Uncertainty in the results was also estimated by means of stochastic calculations based on variation of the site-specific parameter values. This paper describes the generic model and the deterministic and stochastic results obtained when it was applied to the five sites. Details of the site-specific models and the corresponding results are described in two companion papers. This paper also presents a comparison of the results between the generic model and site-specific models. In general, there was an acceptable agreement of the BIOGEM for both the deterministic and stochastic results with the results from the site-specific models.

Body Burden↗
PubMed2005

Development and comparison of five site-specific biosphere models for safety assessment of radioactive waste disposal.

This paper describes the development and application of site-specific biosphere models that might be used for assessment of potential exposures in the framework of performance assessment studies of nuclear waste disposals. Model development follows the Reference Biosphere Methodology that has been set up in the framework of the BIOMASS study. In this paper, the application is to real sites at five European locations for which environmental and agricultural conditions have been described and characterised. For each of the sites a biosphere model has been developed specifically assuming a release of radionuclides to waters that are used by humans, for example as drinking water for humans and cattle and as irrigation water. Among the ingestion pathways, the intakes of drinking water, cereals, leafy vegetables, potatoes, milk, beef and freshwater fish are included in all models. Annual individual doses were calculated, and uncertainties in the results were estimated by means of stochastic calculations. To enable a comparison, all results were normalised to an activity concentration in groundwater of 1 Bq m(-3) for each of the radionuclides considered ((36)Cl, (79)Se, (99)Tc, (129)I, (135)Cs, (226)Ra, (231)Pa, (230)Th, (237)Np, (239)Pu, and (238)U), i.e. those that are usually most relevant in performance assessment studies of nuclear waste disposals. Although the results do not give answers in absolute terms on potential future exposures, they indicate the spectrum of exposures that might occur in different environments and specify the interaction of environmental conditions, human habits and potential exposure.

Animals↗
PubMed2005

A comparative radiological assessment of five European biosphere systems in the context of potential contamination of well water from the hypothetical disposal of radioactive waste.

In the framework of the BioMoSA project for the development of biosphere assessment models for radioactive waste disposal the Reference Biosphere Methodology developed in the IAEA programme BIOMASS was applied to five locations, situated in different European countries. Specific biosphere models were applied to assess the hypothetical contamination of a range of agricultural and environmental pathways and the dose to individuals, following contamination of well water. The results of these site-specific models developed by the different BioMoSA partners, and the individual normalised dose to the exposure groups were compared against each other. Ingestion of drinking water, fruit and vegetables were found to be among the most important pathways for almost all radionuclides. Stochastic calculations revealed that consumption habits, transfer factors, irrigation rates and distribution coefficients (Kd(s)) were the most important parameters that influence the end results. Variations in the confidence intervals were found to be higher for sorbing elements (e.g. (36)Cl, (237)Np, (99)Tc, (238)U, (129)I) than for mobile elements (e.g. (226)Ra, (79)Se, (135)Cs, (231)Pa, (239)Pu). The influence of daughter products, for which the distribution into the biosphere was calculated individually, was also shown to be important. This paper gives a brief overview of the deterministic and stochastic modelling results and the parameter sensitivity. A screening methodology was introduced to identify the most important pathways, simplify a generic biosphere tool and refine the existing models.

Adult↗
PubMed2004

A radioecological model for thyroid dose reconstruction of the Belarus population following the Chernobyl accident.

A radioecological model was developed to estimate thyroid exposures of the Belarus population following the Chernobyl accident. The input of the model includes an extensive data set of the (137)Cs activity per unit area deposited during the Chernobyl accident, the rainfall data for different regions of Belarus, the (131)I/(137)Cs ratio in the deposit and the start of the grazing period in Belarus in April/May 1986. The output of the model is the age-dependent thyroid exposure due to the intake of (131)I with fresh milk. Age-dependent average thyroid doses were assessed for selected regions of Belarus. The maximum thyroid doses were estimated for the inhabitants of Gomel oblast where the highest deposition was observed among the regions considered here. The lowest doses were estimated for Vitebsk oblast with the lowest level of depositions. The mean exposures for the oblasts of Grodno, Minsk, Mogilev and Brest were very similar. The results were compared with estimations of thyroid exposure that were based on (131)I measurements in human thyroids, and they are in good agreement. The model may be used for the assessment of thyroid doses in Belarus for areas where no (131)I measurements are available.

Adult↗
PubMed2004

Absorbed dose rate conversion coefficients for reference terrestrial biota for external photon and internal exposures.

The paper describes dosimetric models that allow the estimation of average radiation exposures to terrestrial biota due to environmental sources in the soil as well as internal uniform distributions of radionuclides. Simple three-dimensional phantoms for 13 faunal reference organisms are specified. The calculation of absorbed dose per unit source strength for these targets is based on photon and electron transport simulations using the Monte Carlo method. The presented absorbed dose rate conversion coefficients are derived for terrestrial reference species. This allows the assessment of internal exposure as well as external photon exposure depending on the nuclide, habitat, target size and environmental contamination. To enable the application of specific radiation weighting factors for alpha-, low energy beta- (E0 < 10 keV), beta- and gamma-radiations, their partial contributions to the total absorbed dose are provided separately. The coefficients for external exposure are listed for organisms living above the ground for an infinite plane source 3 mm deep in soil, as well as for a horizontally infinite volume source uniformly distributed to a depth of 10 cm. Furthermore, the coefficients are also presented for organisms living in a contaminated 50 cm thick soil layer. A multi-layer canopy model for plants is also described. The conversion coefficients are given for 3H, 14C, 40K, 36Cl, 59,63Ni, 89,90Sr, 94Nb, 99Tc, 106Ru, 129,131I, 134,135,137Cs, 210Po, 210Pb, 226Ra, 227,228,230,231,232,234Th, 234,235,238U, 238,239,240,241Pu, 241Am, 237Np and 242,243,244Cm, together with their

Animals↗
PubMed2004

Estimation of internal and external exposures of terrestrial reference organisms to natural radionuclides in the environment.

In this paper, an estimation of the doses absorbed by terrestrial reference organisms due to naturally occurring radionuclides is described. For terrestrial organisms under normal circumstances, external exposure is estimated to be of the order of 0.1-0.4 mGy a(-1), depending on size and habitat, and the main contributor is 40K. Internal background exposures of terrestrial organisms are more variable. Again, 40K is an important contributor giving doses of the order of 0.3 mGy a(-1). The exposures of muscles and plant tissues to uranium, thorium, radium, lead and polonium are lower, but liver, bone and kidney may be exposed at levels of 0.1-1 mGy a(-1) absorbed dose. There can also be significant increases in the received dose under specific environmental conditions as is the case for burrowing mammals that receive relatively high lung doses due to the inhalation of radon and its progeny.

Animals↗
PubMed2001

Model for food chain transfer and dose assessment in areas of the Slovak Republic.

The radio-ecological model ECOSYS-87 developed for German ecological conditions, has been adapted to the conditions of two sub-regions in the Slovak Republic. In particular, the selection of plant varieties used for animal feeding, the plants' growing cycles and harvests, the animal feeding practices and the human consumption rates were subjected to adaptation. Measurements of caesium and iodine radioactivity in soil, plants and animal products that have mainly been performed in the vicinity of the Bohunice nuclear power plant after the Chernobyl accident, are compared with the results of the adapted model. Data from various locations with dry, mixed or predominantly wet deposition show in general good agreement.

Animal Feed↗
PubMed2001

Considerations on the behavior of long-lived radionuclides in the soil.

The migration of radionuclides from waste repositories to the biosphere potentially leads to a contamination of soil. Due to the importance of food production, the mobilisation and accumulation behaviour of long-lived radionuclides in the soil plays a key role in performance assessment studies. In this paper, the main features and processes that control radionuclide behaviour in soil, such as pH, redox potential and sorption to organic and inorganic soil components, are discussed for the radionuclides 36Cl, 79Se, 129I, 99Tc, 237Np and 238U, that are usually most relevant in long-term safety assessments of nuclear waste. The interaction of radionuclide behaviour in soil with environmental factors, such as temperature and humidity as well as farming practices are discussed. The possible impact of future soil development on long-term behaviour in soil are taken into consideration. Due to the physiological constraints of plant growth, appropriate soil conditions for growth will probably not be substantially different from current requirements, bearing in mind that sustainable agriculture strives for optimal plant growth. Against this background, present-day parameters may in general be considered appropriate for roughly estimating the behaviour of radionuclides in the soil-plant system.

Chlorine↗
PubMed2000

Internal exposure from the ingestion of foods contaminated by 137Cs after the Chernobyl accident--report 2. Ingestion doses of the rural population of Ukraine up to 12 y after the accident (1986-1997).

Doses from the ingestion of 134Cs and 137Cs during 12 y following the Chernobyl accident have been estimated for approximately 3 million persons living in rural areas of the Zhitomir, Rivne, and Kyiv Oblasts of northern Ukraine. This assessment is based upon an extensive monitoring campaign that provided measurements of 137Cs in more than 120,000 samples of milk and in more than 100,000 persons; such measurements were made in approximately 4,500 locations. Two approaches were used for the dose assessment. In the first approach a so-called reference dose is estimated for each settlement on the basis of measured 137Cs concentration in milk, determination of the milk equivalent of diet, and consumption rates; a further assumption is that a high fraction of the food consumed is produced locally. The reference dose is used as the official dose estimate, which is the basis for any decision on possible financial compensation and economic privileges. In a second step, the so-called real age-dependent dose is estimated from the results of whole body counter measurements and the kinetics of radiocesium in the human body. Real doses above 0.5, 5, and 50 mSv were received by about 40%, 10%, and 0.2%, respectively, of the considered population. With the exception of 1986, for which the monitoring results were limited, the real individual doses derived from whole-body counting are consistently lower than the reference doses. However, this difference declined from a factor of 3-4 in 1987-1989 to a factor of approximately 1.5 in the mid 1990's. The difference between reference and real doses is attributed to the effectiveness of countermeasures implemented after the accident. The effectiveness of these countermeasures decreased with time due to increasing economic problems in Ukraine. The collective reference and real doses of the rural population due to the intake of 134Cs and 137Cs are estimated to be 13,300 and 5,300 person-Sv, respectively. Thus, about 8,000 person-Sv is estimated to have been averted by countermeasures.

Age Factors↗
PubMed1999

Modelling radionuclide distribution and transport in the environment.

Mathematical models of radionuclide distribution and transport in the environment have been developed to assess the impact on people of routine and accidental releases of radioactivity from a variety of nuclear activities, including: weapons development, production, and testing; power production; and waste disposal. The models are used to estimate human exposures and doses in situations where measurements have not been made or would be impossible or impractical to make. Model results are used to assess whether nuclear facilities are operated in compliance with regulatory requirements, to determine the need for remediation of contaminated sites, to estimate the effects on human health of past releases, and to predict the potential effects of accidental releases or new facilities. This paper describes the various applications and types of models currently used to represent the distribution and transport of radionuclides in the terrestrial and aquatic environments, as well as integrated global models for selected radionuclides and special issues in the fields of solid radioactive waste disposal and dose reconstruction. Particular emphasis is placed on the issue of improving confidence in the model results, including the importance of uncertainty analysis and of model verification and validation.

Journal Article↗
PubMed1998

Thyroid dose and thyroid cancer incidence after the Chernobyl accident: assessments for the Zhytomyr region (Ukraine).

In the Zhytomyr region, about 52,000 measurements of the 131I activity in thyroids were performed. On the basis of these measurements, individual doses have been assessed for the people monitored and age-dependent average doses have been estimated for those settlements with more than 11 direct measurements. In order to estimate the pattern of thyroid exposure in the Zhytomyr region, these doses have been interpolated or extrapolated to population groups who were not monitored during May-June 1986. For this purpose, a model has been developed based on a correlation between thyroid dose estimates with the 137Cs deposition and the co-ordinates of the settlements relative to Chernobyl. Collective doses of people who were born in the years 1968 to 1986 were calculated. The radiation-induced thyroid cancer incidence in the period 1991 to 1995 was assessed by subtracting the spontaneous incidence from the observed incidence. The result is considerably lower than that observed in longer periods after external exposures. Possible reasons for this difference are discussed.

Adolescent↗
PubMed1997

The transfer of 137Cs from barley to beer.

Beer has been brewed from barley contaminated with 137Cs as a consequence of the Chernobyl accident. The 137Cs activity has been measured in all intermediate steps and in the by-products of the production process. About 35% of the 137Cs in barley were recovered in beer. Processing factors defined as the concentration ratio of processed and raw products were determined to be 0.61, 3.3, 0.1 and 0.11 for malt, malt germs, spent grains and beer, respectively.

Beer↗
PubMed1997

Adaptation of ECOSYS-87 to Hong Kong environmental conditions.

This paper describes the adaptation work carried out on the radioecological model ECOSYS for radionuclide transfer in the Hong Kong ecological environment. The adapted model predicts that the ingestion dose due to dry deposition in Hong Kong shows less pronounced seasonal dependence than that in Germany. This is mainly attributed to differences in climate, agricultural and farming practices adopted in the two places. Brief discussions on model sensitivity, uncertainty, and validation are also given.

Agriculture↗
PubMed1996

Factors affecting the transfer of radiocaesium from soil to roe deer in forest ecosystems of southern Germany.

Since 1987, in Southern Germany, as a consequence of the Chernobyl accident, the 137Cs activity concentration in roe deer (Capreolus capreolus) has been intensively monitored. A large data set is now available with approximately 5000 samples, with information about the location of the animal, the time of slaughtering, soil characteristics and distance to intensively managed agricultural land. Both the roe deer 137Cs activity concentrations and aggregated transfer coefficients soil-roe deer (T(ag,r)) show a considerable variability with geometric mean and geometric standard deviation in meat of 270.3.5 +/- 1 Bq.kg-1 and 0.01.3.5 +/- 1 m2.kg-1, respectively. From 1987 to 1991, T(ag,r) values exhibited a decline with an ecological half-life of about 3 years. Since 1991, no further decrease of the roe deer contamination level was observed. This general trend is superimposed by an increase in T(ag,r) in autumn that has occurred in almost every year, which is probably due to consumption of mushrooms. This hypothesis is supported by a significant positive correlation between the precipitation during July and August, stimulating the fungi's growth and the height of the maximum in T(ag,r) in autumn. Animals are less contaminated when living in parts of the forest from where they have access to intensively managed agricultural land. A small, but significant correlation is observed between the T(ag,r) and soil parameters; the total potassium content of the soil and the pH of the organic soil layer. The highest transfer coefficients soil-roe deer were found on a peat bog, where most values ranged from 0.01-0.1 m2.kg-1, and neither a pronounced seasonal variation, nor a long-term decrease was observed. On sites with coniferous forests, most T(ag,r) values range from 0.005 to 0.05 m2.kg-1, on sites with a mixture of coniferous and deciduous trees, the transfer coefficients range mostly from 0.002 to 0.02 m2.kg-1. This is a further indication of the importance of the uppermost soil layers and the biological processes therein with respect to the bioavailability of caesium. On the two sites, the values at the lower boundary are more typical for animals that have access to agricultural areas, whereas the higher values were observed in autumn and for animals grazing distant from agricultural areas.

Animals↗
PubMed1996

Radiation exposure from radionuclides in ground water: an uncertainty analysis for selected exposure scenarios.

The uncertainty of the potential radiation exposure of the general population has been estimated for a normalized contamination of ground water that is being used as drinking water for humans and animals, for irrigation of food and feed crops, and for fish production in freshwater bodies. The frequency distributions of annual effective dose equivalents were calculated assuming a normalized activity concentration in water of 1 Bq/l for each radionuclide considered. Estimated frequency distributions of the parameters were used as model input. This estimation is based on an exposure scenario which reflects the present radioecological conditions. Another important source for the uncertainty of the potential dose due to radionuclides released to the ground water is the uncertainty of the exposure scenario. Since such a contamination may not occur before some time in the far future, it is impossible to predict the exact boundary conditions. Therefore, scenarios were stimulated with modified consumption habits, more extensive farm management and different climatic conditions. The distributions of the potential doses cover in general about a factor of 10-20. The intake of drinking water, the root uptake and the contamination of fish are most important for the resulting potential radiation exposure. For nearly all radionuclides, the intake of drinking water dominates the potential exposure. In most cases radioactive daughter nuclides are of minor importance. In general, the influence of the exposure scenario on the dose is relatively small.

Animals↗