[en] The migration behaviour of transuranic elements Np, Pu, Am and Tc has been studied by static and dynamic experiments under aerobic as well as anaerobic (N₂ + 3% H₂) conditions for the geological samples from Gorleben aquifers (Germany) and also for the glauconite mineral. The geochemical parameters varied are: pH from 5 to 7, Eh by addition of SnCl₂ or hydrazine and salinity with NaCl concentration from 0.01 to 3.0 M

[en] Based on standards of EPA and IEEE, quality criteria have been formulated which address the development of air pollution models, the transformation towards user-friendly software and ''after-sales'' service. A Dutch standard on the description of air pollution models is being finalized. The standard formulates minimal requirements on the theoretical and practical description of models. This paper provides a survey of the quality criteria and it summarizes the standard. Further, the current practice of model development at RIVM is discussed. (au) (24 refs.)

[en] Annual consumption of 10 classes of food and drink is reported for the total population of each EC-country. National food consumption data are generalized by distinguishing groups of countries with similar diet. Group 1: UK and Ireland (low consumption of fruit, high consumption of potatoes and fresh dairy products). Group 2: Italy and Greece (high consumption of cereals, vegetables and fruit, low consumption of fresh dairy products). Group 3: France, Belgium, Luxembourg, Netherlands, FRG and Spain (intermediate consumption of most foodstuffs). Portugal and Denmark could not be classified in any group. Changes in food consumption related to differences in age, sex, social class, regional habits and level of urbanisation are reported.In some cases, variation of annual food consumption over the different seasons on the relative contribution of food from local origin to the total diet, could be estimated. Differences of region, age and level of urbanisation appear to have the largest influence on consumed amounts. As for age, the values for the different age-groups range from 50 to 80 percent of the adult diet. Regional consumption may diverge from 70-130 percent of the average national consumption, with values of 200 percent for potatoes and fruit. Consumption in urban areas compared with the entire country diverges from 70-100 percent. In rural areas the values diverge from 100-140 percent. Self-support of vegetables and milk seems to be important for most countries. Of the other products, self-support of wheat and cheese is only of importance in the south of the EC. When combining the effects of the different factors, a range of consumed amounts for specific population groups of 50 to 200 percent of the average national consumption was determined. (author). 38 refs.; 13 figs.; 75 tabs

[en] This standard establishes requirements which the description of mathematical models for air quality has to meet. The standard is applicable to models which assist in calculating the concentration of compounds in the air and/or the deposition. Users should be able to judge the usefulness of a mathematical model for their own use on the basis of its description. This is often necessary for granting licences or policy planning. Equipment, software and other requirements are not given. The description of a mathematical model should give the user a good insight into the value of the model and the results obtained. To do this the field of application and the underlying scientific concepts should be clearly described. Besides the results of possible validation procedures the way in which broader acceptance is aimed at and the degree to which this is achieved has to be reflected. (au)

[en] The Dutch research program on the geological disposal of radioactive waste was designed to supply a basis for the selection of combinations of three factors, i.e., type of rock-salt formation, site, and disposal technique, satisfying radiological standards and other criteria for final disposal. The potential sites have been grouped according to the type of rock-salt formation (e.g. bedded salt and salt domes) and two classes of depth below the surface of the ground. Values for geohydrological parameters were obtained by extrapolation of data from existing boreholes and analysis of the sedimentary environment. A three-dimensional model of groundwater flow and contaminant transport, called METROPOL, has been developed. To investigate the effect of high salinity on nuclide transport properly, a theoretical experimental study was carried out. Use of a thermodynamic approach showed that terms related to salt mass fraction have to be added to Darcy's and Fick's laws. An experimental study to investigate effects of these modifications is in progress. 8 refs.; 8 figs.; 1 table

[en] Between 1981 and 1988 an important number of data was collected on the transfer from soil to grass of Cs-137, Sr-90, Zn-65, C0-60 and Mn-54. On the basis of analyses of 28 harvests an evaluation is made of the time trend of the soil-to-grass transfer. The resemblance between the fluctuations at the various sites and a sometimes striking contrast between successive years clearly indicate variations in weather conditions to be an important cause of variation. Weather conditions affect both active uptake (as was apparent for Sr-90) and external contamination contamination (of importance for Co-60 and Cs-137). They cause fluctuations in the concentration of radionuclides in plants which mask the effect of their progressive fixation by the soil. (author)

[en] The influence of pH, soil organic matter content and soil moisture conditions on the uptake of Cs, Sr, Pu, Am, Np and Co by grass, cereals and some other crops was determined by analysing data of a data bank. The results, extrapolated to extreme environmental conditions, are shown as figures which include regression curves. (author)

[en] Results from long-term lysimeter experiments on soil-to-plant transfer of Cs and Sr were re-analysed to study the impact of ageing and climatic conditions. The experimental design allowed the effects of both parameters on the transfer to be distinguished. Transfer of Cs to edible parts of several plant species gradually decreased as a result of ageing. This decrease is estimated to be a factor of 1.5 after 1-2 years, up to a factor of 4 after 7 years. Transfer of Sr did not change when its residence time in the soil increased. After correction for effects of ageing, annual fluctuations of up to a factor of 10 were found, dependent on the plant species. These fluctuations were attributed to the effects of climatic conditions. The transfer of Sr to several plant species appeared to increase with increasing rainfall or with decreasing intensity of light, hours of sunlight or temperature. A negative correlation was found between the transfer of Cs to spinach and the amount of rainfall. (author)

[en] A new nonparametric method, called the relative comparison method, is presented to evaluate the effect of some soil parameters on transfer of Cs or Sr from soil to edible plant parts. A large number of transfer factors is used for ¹³⁴Cs, ¹³⁷Cs, ⁸⁵Sr, ⁸⁹Sr and ⁹⁰Sr. Transfer of Cs increased with increasing organic matter content. Compared to the transfer of Cs in soils with an organic matter content of less than 5%, the effect was approximately a factor of 2-5 to 20% and increased up to a factor of 10 in soils with an organic matter content of more than 50%. In contrast, transfer of Sr decreased with increasing soil organic matter content. Relative to the transfer of Sr in soils with an organic matter content of less than 5% the decrease was by about a factor of 1.5 at 6-10% organic matter up to a factor of 10 in soils with an organic matter content of more than 50%. In the range pH 3.9-8.4, transfer of Cs was not affected by soil pH. On average, transfer of Sr decreased by a factor of 1.7 when soil pH increased from pH 4.5 to 7.4. Transfer of Cs in clay or loam was lower than in sand, by five or three times, respectively. For Sr the transfer in clay or loam was about 1.4 times lower than in sand. These results may be used as correction factors when evaluating soil-to-plant transfer factors of Cs or Sr. (author)

[en] The significance of the reductions in radionuclide contamination of foodstuffs that result from food processing and culinary preparation has been recognised for many years. However, the information available on the reduction factors achieved by the various processes and as a function of radionuclide was scarce and poorly documented. The need for realistic dose assessments after the Chernobyl release made modelling deficiencies of this type apparent and stimulated new work in the area. The effects of processing on the behaviour of radionuclides depend on the radionuclide, on the type of product and on the method of processing. In general, food processing may value the amount of radionuclides present in food. The effects are rather small for root crops, whereas milling grains to flour will often remove about 70% of the radioactivity. The effects of processing on meat, fruits and vegetables are also discussed. 104 refs, 2 figs, 8 tabs