30-y follow-up of a Pu/Am inhalation case

In 1983, a young man inhaled accidentally a large amount of plutonium and americium. This case was carefully followed until 2013. Since no decorporation measures had been taken, the undisturbed metabolism of Pu and Am can be derived from the data. First objective was to determine the amount of inhaled radionuclides and to estimate committed effective dose. In vivo and excretion measurements started immediately after the inhalation, and for quality assurance, all types of measurements were performed by different labs in Europe and the USA. After dose assessment by various international groups were completed, the measurements were continued to produce scientific data for model validation. The data have been analysed here to estimate lung absorption parameter values for the inhaled plutonium and americium oxide using the proposed new ICRP Human Respiratory Tract Model. As supplement to the biokinetic modelling, biological data from three different cytogenetic markers have been added. The estimated committed effective dose is in the order of 1 Sv. The subject is 30 y after the inhalation, of good health, according to a recent medical check-u

Active tectonics and earthquake destructions in caves of northern and central Switzerland

The present publication focuses on the study of caves in northern and central Switzerland in order to detect and date historical earthquakes and active tectonic displacements by investigations of broken and resealed or displaced speleothems datable by U/Th and 14C. While it can be shown that these methods are potentially suitable, the ages obtained are often beyond the range of historically recorded earthquakes, and it cannot be proved that the observed and dated events are related to a seismic event. Particularly this is true for the caves in central Switzerland, where most ages in the Melchsee-Frutt region were beyond the limits of the U/Th method, or of late Pleistocene age in the Siebenhengste-Hohgant region. A direct comparison with known historical (or prehistoric) earthquakes was not possible. In contrast to central Switzerland, the results in the Basle region of northern Switzerland indicates cave and speleothem damages in one cave within the epicentral area of the 1356 Basle earthquake. 14C datings allowed to directly relate the speleothem damages to this M 6.5 earthquake. Further dating results from caves in northern Switzerland on speleothems and organic material in cave deposits supplied ages which indicate older events not related to the historical Basle earthquake. The detection of active fault displacements and prehistoric strong earthquakes can only be achieved by a very careful deciphering of the palaeo-environmental records and many more age determinations which allow to separate active tectonic displacements and seismic events from other events not related to tectonics, i.e. glaciations, creep of sediments, catastrophic floods etc

Ra-partitioning between phlogopite and silicate melt and ^(226)Ra/Ba–^(230)Th/Ba isochrons

In this study we experimentally determine phlogopite/melt partition coefficients of Ra and other trace elements in a lamproitic system. This work was achieved using an analytical technique (LA-ICP-MS) with low detection limits (~0.01 fg) permitting the measurement of the very low Ra concentrations feasible in experiments (~1 ppb). D_(Ra)^(phlogopite/melt) was determined to 2.28 ± 0.44 and 2.84 ± 0.47 in two experiments, the ratio D_(Ra)/D_(Ba) is around 1.6. The compatibility of Ra in phlogopite results from an ionic radius being close to the apex of the lattice strain parabola for earth alkalis in the large XII-coordinated interlayer site of phlogopite. A re-evaluation of D_(Ra) and D_(Ra)/D_(Ba) for magmatic minerals containing appreciable Ra, yields D_(Ra)^(mineral/melt) ranging from ~2.6 for phlogopite down to 2–3 • 10^(−5) for pyroxenes, and D_(Ra)/D_(Ba)^(mineral/melt) from ~4 for leucite to 2 • 10^(−2) for orthopyroxene. The influence of melt composition on D_(Ra)/D_(Ba) is less than 10%. All investigated minerals have different D_(Ra)/D_(Ba), strongly fractionating Ra from Ba. Thus, for magmatic systems, (^(226)Ra)/Ba in the various minerals is not constant, these minerals do not form a straight line in the (^(226)Ra)/Ba–(^(230)Th)/Ba system at the time of crystallization and thus, there is no (^(226)Ra)/Ba–(^(230)Th)/Ba isochron at t_0. 226Ra–230Th–Ba mineral dating is thus applicable only to model ages calculated from mineral–glass pairs with known D_(Ra)

Aufnahme radioaktiver Stoffe durch Erdbeer· und Rebenblätter

Radioactive strontium in the form of an aqueous solution of 85 5rCl 2 was taken up by the leaves of strawberry plants and grapevines at different rates. Only a limited amount was transported from · the contaminated leaves into other plant organs. However, no strontium was found in the fruit. In contrast, radioactive caesium applied as an aqueous solution of 134CsCI was taken up very quickly from the leaf surface, transported from there to other plant parts and released to some extent into the soil via the roots. In our investigations, strawberry fruit showed a high caesium content. The caesium content in grape berries rose during growth and decreased again in a late phase of maturation and the nuclide was partly redistributed to other plant parts. Caesium reaching the soil may interact with day particles resulting in a very limited availability for plants. First results of investigations with grapevines in hydroculture demonstrated a close relationship between potassium supply and caesium release. The foliar up· take of radioactive strontium into plants is minor and represents therefore a negligible risk for the consumer of fruits. Radio· active caesium nuclides may however reach the human food chain through the leaves of food plants

Increased uranium concentrations in ground and surface waters of the Swiss Plateau: A result of uranium accumulation and leaching in the Molasse basin and (ancient) wetlands?

Increased uranium (U) concentrations are found in certain ground and surface waters of the Swiss Plateau. Analysis of more than 100 public fountains revealed that increased 238U concentrations frequently occur close to the interface between the Lower Freshwater Molasse and the Upper Marine Molasse, cropping out in the western part of the Swiss Molasse Basin. Out of these locations, Mont Vully, situated ca. 20 km west of Berne, was studied in detail. As this hill consists of the two aforementioned stratigraphic Molasse units, it represents an ideal case study. Two springs at the northern slopes of Mont Vully exhibit the highest 238U concentrations with more than 300 mBq/L and were thus monitored for almost two years in order to screen possible seasonal variations. Further water samples were collected from spring captures, creeks and drainage pipes. The pipes drain the farmland north of Mont Vully showing 238U concentrations with more than 600 mBq/L. In order to discover the reason for the duplication in concentration, gamma dose rate measurements were accomplished on the farmland, revealing elevated dose rates of up to 160 nSv/h. These are located above ancient pathways of creeks that originated from Mont Vully. At these locations with elevated dose rates, three shallow sediment drill cores were taken and analyzed for their U content. The sediment cores can essentially be divided into three parts: (i) an upper soil with common U concentrations of about 30 Bq/kg 238U, (ii) an U-rich peat horizon with concentrations of up to 500 Bq/kg 238U, and (iii) an impermeable clay unit that acts as an aquitard with again minor 238U concentrations. Radiocarbon dating of the U-rich peat horizon reveals ages younger than 8.1 kyrs. This study suggests that a wetland was formed on top of the impermeable clay layer after the last glaciation during the Holocene. The stream waters with 238U concentrations of more than 300 mBq/L originating from Mont Vully contributed significantly to the water supply for the development of the wetland. Due to the reducing conditions that are present in wetlands, the dissolved U in the incoming streams was reduced and adsorbed onto organic matter. Accordingly, an entrapment for U was generated, persisting for at least 6 kyrs – a sufficient time to accumulate up to 500 Bq/kg. In the course of the last century, numerous wetlands in Switzerland were drained by capturing streams and installing drainage pipes to make the land suitable for agriculture. This kind of melioration was also done at the wetlands north of Mont Vully resulting in a subsequent change in redox conditions within the soil. The solubility of U depends on its oxidation state and U can be oxidized by oxygen-rich rainwater. The rainwater leached the U adsorbed on the peat yielding 238U concentrations of more than 600 mBq/L. Consequently, the duplication of 238U concentrations in the drainage water as compared to the original concentration that creeks brought into the ancient wetlands has been clarified during this study. Twenty of the analyzed public fountains in the Swiss Plateau exhibited a 238U concentration of more than 50 mBq/L. All of them could have contributed to the formation of a wetland after the last glaciation, which leads to the assumption that the situation at Mont Vully is not a singularity in the Swiss Plateau

Uptake and Transport of Radioactive Cesium and Strontium into Strawberry Plants and Grapevines After Leaf Contamination

Radioactive strontium in the form of a carrier-free aqueous solution of 85SrCl2 was taken up by the leaves of strawberry plants and grapevines at different rates. Only a limited amount was transported from the contaminated leaves into other plant organs. However, no strontium was found in the fruit. These findings show that bivalent strontium is mobile in plants only to a very minor extent. In contrast, radioactive cesium applied as an aqueous solution of carrier-free 134CsCl was taken up very quickly from the leaf surface, transported from there to other plant parts and released to some extent into the soil via the roots. In our investigations, strawberry fruit showed a high cesium content. The cesium content in grape berries rose during growth and decreased again in a late phase of maturation and the nuclide was partly redistributed to other plant parts. Cesium reaching the soil may interact with clay particles resulting in a very limited availability for plants. First results of investigations with · grapevines in hydroculture demonstrated a close relationship between potassium supply and cesium release. The foliar uptake of radioactive strontium into plants is minor and represents therefore a negligible risk for the consumer of fruits, berries and nuts. Radioactive cesium nuclides may however reach the hum.an food chain through the leaves of food plants

The tritiated water and iodine migration in situ in Grimsel granodiorite. Part I: determination of the diffusion profiles

International audienc

Availability of Zinc and the Ligands Citrate and Histidine to Wheat: Does Uptake of Entire Complexes Play a Role?

Organic ligands in soils affect the availability of trace metals such as Zn to plants. This study investigated the effects of two of these ligands, citrate and histidine, on Zn uptake by wheat under hydroponic conditions. Uptake of ⁶⁵Zn in the presence of these ligands was compared to uptake in the presence of EDTA at the same free Zn concentration (Zn²⁺ ∼ 50 nM). In the presence of citrate Zn root uptake was enhanced ∼3.5 times and in the presence of histidine, by a factor of ∼9, compared to the EDTA treatments. Citrate uptake was slightly reduced in the treatment containing ligands and Zn compared to the treatment containing the same ligand concentration but no Zn. In addition, a higher uptake of Zn than of citrate was observed. This suggests that the enhanced Zn uptake was primarily due to increased supply of Zn²⁺ by diffusion and dissociation of Zn–citrate complexes at the root surface. Histidine uptake was much higher than citrate uptake and not influenced by the presence of Zn. As histidine forms stronger complexes with Zn than citrate, the results suggest that the enhancement of Zn uptake in the presence of histidine was in part due to the uptake of undissociated Zn–histidine complexes