Search

A chemical separation procedure for plutonium (Pu) and neptunium (Np) was developed using extraction chromatography, mass spectrometry and radiometric analysis to determine their concentrations and isotopic ratios in sea water. 241Am, which causes isobaric background to 241Pu in mass spectrometric measurements, was successfully separated from the Pu fraction by this method. Water samples which were spiked with 242Pu and 237Np or 239Np, respectively, were used for chemical yield determination. The chemical yields of Pu and Np, which were determined by alpha and gamma spectrometry at the Radiochemie Munchen (RCM), of more than 85% were obtained. The developed method was applied to analyze the concentration of Pu and Np in the certified reference material, IAEA-443, by Accelerator Mass Spectrometry (AMS) at the Maier–Leibnitz-Laboratory (MLL) to check the applicability of the method to sea water samples. The concentrations of 240Pu, 241Pu and 237Np obtained in this study are in agreement with the certified and literature values within the uncertainties. Due to strong isotopic interference of 239Pu with 238U, it was not possible to analyze the concentration of 239Pu. Some modifications of the chemical separation method to suppress the uranium (U) fraction are under consideration. This method can be used for the analysis of Pu and Np in Pacific Ocean water samples collected after the Fukushima accident.

The dry deposition to several leafy vegetables (endive, head lettuce, red oak leaf lettuce, spinach) was studied. Particles with attached 134 Cs were used for testing the particulate deposition, gaseous elemental 131 I was the tracer for gas deposition. The particle deposition was the highest for rough and structured leafs as red oak leaf lettuce has, but as well for spinach with many open stomata. The stomatal uptake seamed to be the most important process for gas deposition, the deposition to spinach was for Radioiodine the highest as compared to all other species. The lowest deposition was always found to the closed heads of head lettuce. The difference in deposition to the various species was up to a factor 9.

The concentrations of iodine in cereal grains cultivated at 38 locations in Austria from cereal-producing sites in agricultural areas and soil-to-grain transfer factors (TF) were determined. The concentrations of iodine in cereal grains, which were analyzed by radiochemical neutron activation analysis ranged from 0.002 to 0.03 microg g(-1), the arithmetic mean and the median were 0.0061 microg g(-1) and 0.0046 microg g(-1), respectively. The TF values for cereal grains were calculated to be 0.0005-0.02 and the median was 0.0016. The TF values correlated positively with the iodine concentrations in cereal grains. However, the TF values correlated negatively with the iodine concentrations in soils as well as with the amount of clay contents of soils. The TF values were almost independent on pH values (5.4-7.6) of soils.

The mobility of 46 Sc, 54 Mn, 58 Co, 74 As, 75 Se, 83 Rb, 85 Sr, 88 Y, 149 Eu, 146 Gd, 169 Yb, 175 Hf, 183 Re, and 192 Ir in soybean plants after foliar deposition was determined by a multitracer experiment. The plants were grown in a controlled area under no-rain conditions for different periods. They were exposed to multitracer-absorbed cellulose powder, and the radionuclide content in the seeds, pods, corpus, tunica, and roots was determined after they were harvested. Rubidium showed the highest mobility in the plant among those radionuclides followed by Se and Co which were classified as `mobile'. Mn, As, Sr, and Re form a second class of `medium mobility'. The contents of 46 Sc, 88 Y, 149 Eu, 146 Gd, 169 Yb, 175 Hf, and 192 Ir were below the detection limit in the seeds; these elements are classified as `immobile'. The data obtained in this experiment cannot directly be converted into translocation factors applied in radioecological models, but they allow to check the classification used presently in such a model for elements on which little or no information is available at present.

The transfer factor of radionuclides of Na, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Tc, Rh and Cs in komatsuna (Brassica rapa L. var. perviridis Bail) at different stages of plant development was determined simultaneously by the multitracer technique. Komatsuna was grown on soil administered with the multitracer for 14, 20, 26, and 33 days. The transfer factors were determined not only for edible leaves but also for roots. It was found that the transfer factors of Rb, Tc, and Cs for the leaves decreased with increasing culture period, while those of Na, Co, Zn, Se, and Sr for leaves remained almost constant during the culture period. The transfer factor of Mn increased slightly with time. Extraction of the multitracer from the soil was carried out in order to study the correlation between the transfer factor and the aging effect of tracers in soil.

The uptake rate of95mTc,83Rb, and65Zn by soybean plants cultivated in soil was measured during 2≈247 hrs by a multitracer technique. The uptake amount in most of the leaves and stems increased up to 150≈200 hrs after the administration of the multitracer and then decreased with time. The uptake amount of65Zn in the youngest fruit increased until 120 hrs and then decreased with time, and83Rb uptake reached almost a constant amount after 120 hrs. On the other hand, the uptake amount of95mTc in the youngest fruit increased continuously up to 247 hrs. The behavior of elements in the leaves and stems was analyzed mathematically with the second order function,Ar=c+k1t+k2t2, 0

The direct absorption of atmospheric elements via soybean leaves has been studied using a radioactive multitra œr technique. Soybean was cultivated until it bore seeds in a box under no-rain conditions and with introduction of multitracer-adsorbed cellulose powders. The radioactive nuclides of 40 elements were produced from Au target irradiated with14N, and the nuclides with relatively long half-life of the elements Sc, Mn, Co, As, Se, Rb, Sr, Y, Eu, Gd, Yb, Re, and Ir were dominantly observed in each part of soybean plant.

The chemical states of iron in sixteen Antarctic meteorites belonging to H-group chondrites were studied by means of Mossbauer spectroscopy. An Fe-Ni alloy, troilite, paramagnetic Fe(III), and two kinds of paramagnetic Fe(II) were observed in each meteorite. The Mossbauer parameters indicated that the Fe(II) components can be assigned to olivine and some pyroxenes. The relative area intensities of Fe(III) in the chondrites correlated positively with iodine content, which was determined by radiochemical neutron activation analysis, and those of two Fe(II)-species correlated negatively with the content. On the basis of the data on the halogen and the Mossbauer spectrocopy, the terrestrial contamination on Antarctic meteorites is discussed.

The chemical states of iron in fourteen Antarctic H chondrites were studied by means of Mossbauer spectroscopy. Fe 3+ , Fe 3+ , troilite, and Fe-Ni alloy were analyzed in all meteorites. Determinations of Cl and I in 28 Antarctic H, L, and LL chondrites were carried out by radiochemical neutron activation analysis, and those in three Antarctic eucrites were carried out by isotope dilution mass spectrometry. The results ranged from 90 to 1700 ppm for Cl and from 0.07 to 5 ppm for I in ordinary chondrites, and from 30 to 330 ppm for Cl and from 1 to 9 ppm for I in eucrites. On the basis of the data on halogens and the Mossbauer spectroscopy, terrestrial weathering of Antarctic meteorites are discussed. The relative amount of Fe 3+ in H chondrites correlates positively with chlorine and iodine contents, and Fe 2+ and troilite correlate negatively. Chlorine shows a higher enrichment in ordinary chondrites than in eucrites whereas the I enrichment seems to be larger in Fe-Ni alloy-poor meteorites.