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Fallout radionuclides (7)Be and (210)Pb have been identified as potentially relevant temporal tracers for studying soil particles dynamics (surface vs. subsurface sources contribution; remobilization of in-channel sediment) during erosive events in river catchments. An increasing number of studies compared (7)Be: (210)Pb activity ratio in rainwater and sediment to estimate percentages of freshly eroded particles. However, the lack of data regarding the spatial and temporal variability of radionuclide wet deposition during individual storms has been identified as one of the main gaps in these estimates. In order to determine these key parameters, rainwater samples were collected at three stations during four storms that occurred at the beginning of the monsoon (June 2013) in the Houay Xon mountainous catchment in northern Laos. Rainwater (7)Be and (210)Pb activities measured using very low background hyperpure Germanium detectors ranged from 0.05 to 1.72 Bq L(-1) and 0.02 to 0.26 Bq L(-1), respectively. Water δ(18)O were determined on the same samples. Total rainfall amount of the four sampled storms ranged from 4.8 to 26.4 mm (51 mm in total) at the time-fractionated collection point. Corresponding cumulative (7)Be and (210)Pb wet depositions during the sampling period were 17.6 and 2.9 Bq m(-2), respectively. The (7)Be: (210)Pb activity ratio varied (1) in space from 6 to 9 for daily deposition and (2) in time from 3 to 12 for samples successively collected. Intra-event evolution of rainwater (7)Be and (210)Pb activities as well as δ(18)O highlighted the progressive depletion of local infra-cloud atmosphere radionuclide stock with time (washout), which remains consistent with a Raleigh-type distillation process for water vapour. Intra-storm ratio increasing with time showed the increasing contribution of rainout scavenging. Implications of such variability for soil particle labelling and erosion studies are briefly discussed and recommendations are formulated for the collection of rainwater signature in studies based on the (7)Be: (210)Pb ratio method, especially in tropical areas under high erosive pressure., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The radioactivity levels in the air of the radionuclides released by the Fukushima accident were measured at the Laboratoire Souterrain de Modane, in the South-East of France, during the period 25 March-18 April 2011. Air-filters from the ventilation system exposed for one or two days were measured using low-background gamma-ray spectrometry. In this paper we present the activity concentrations obtained for the radionuclides (131)I, (132)Te, (134)Cs, (137)Cs, (95)Nb, (95)Zr, (106)Ru, (140)Ba/La and (103)Ru. The activity concentration of (131)I was of the order of 100 μBq/m(3), more than 100 times higher than the activities of other fission products. The highest activities of (131)I were measured as a first peak on 30 March and a second peak on 3-4 April. The activity concentrations of (134)Cs and (137)Cs varied from 5 to 30 μBq/m(3). The highest activity concentration recorded for Cs corresponded to the same period as for (131)I, with a peak on 2-3 April. The results of the radioactivity concentration levels in grass and mushrooms exposed to the air in the Modane region were also measured. Activity concentrations of (131)I of about 100 mBq/m(2) were found in grass., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The reported radiochemical results obtained on 77 samples collected from Moroccan fossil beaches assumed to be deposited during the above present sea-level high stands corresponding to 5e climatic stage, and on 12 present and Holocene samples, are discussed in order to judge the age validity. Contrary to the Holocene shells where (238)U contents are low and (234)U/(238)U are in agreement with sea-water ratio, the 5e results vary considerably irrespective of species and calcite content of samples. Because of the open-system possibility, the (230)Th/(234)U ages based on shell samples should be interpreted as minima for any studied shoreline discussed in the light of geological data and several shells analyses.

Analysis results (238U, 234U, 226Ra, 228Ra activities; 234U/238U, 228Ra/226Ra and 226Ra/238U activity ratios) are reported for 4 sediment and 5 suspended mater samples collected from the Low Moulouya region at the North-east of Morocco and for 18 natural water samples collected from the High Moulouya region (Moulouya river, effluents, wells, springs, lakes, barrages and tap water). For sediment and suspended matter, activities of U and Ra isotopes were measured by gamma spectrometry. For water samples, activities and activity ratios of uranium isotopes were measured by alpha spectrometry whereas those of radium were measured by gamma spectrometry. Uranium and radium activities are higher in sediment and suspended matter than in water samples. They are also higher in suspended matter than in sediments because sediments contain the concentrated leached detrital soils and sable. The measured activities of uranium and radium isotopes in all analysed water samples are comparable to those already published in our previous works except for two samples collected from lakes situated at Zeida area. These lakes are the former sites of mine extraction where the accumulated water is in permanent contact with mines. These mines could contain uranium witch responsible of the relatively elevated activities of 234U and 238U found for the first time in lakes water in Morocco. [ABSTRACT FROM AUTHOR]

A reference material designed for the determination of natural radionuclides in solid samples (glass pellets) is described and the results of certification are presented. The material has been certified for 7 natural radionuclides (K, Ra, Ra, Th, Th, U and U). An information value is given for Pb. Radon (Rn) emanation experiments showed results comparable within participating laboratories, however, the number of data and precision was too low to carry out a certification process. The reference material may be used for quality management of analytical laboratories engaged in the high-sensitive analysis of radionuclides in the construction materials of detectors placed in ultra low background underground laboratories. [ABSTRACT FROM AUTHOR]

We analysed dinoflagellate cyst assemblages in four short sediment cores, two of them dated by radionuclides, taken in the south basin of the Caspian Sea. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the biomass of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last few millennia, we show that the main forcing of the increase of L. machaerophorum percentages and of the recent dinocyst abundance is global climate change, especially sea surface temperature increase. Sea level fluctuations likely have a minor impact. We argue that the Caspian Sea has entered the Anthropocene. [ABSTRACT FROM AUTHOR]

For the U-Th series radionuclides investigation in natural freshwater, a simple, fast, and not laboratory intensive method which consists of evaporating the water samples to dryness in the presence of carriers is presented. The small volume of the residue (1-2 cm[SUP3]) leads to a good efficiency for γ counting and limits the self-absorption effect for the low energy γ rays (less than 200 keV). The best efficiency is obtained with a well-type Ge detector. To determine the evaporation yields a river with a common uranium content, the Seine river (France), was selected. By using internal spikes and more conventional techniques of investigation, we demonstrate that the evaporation is quantitative for U, Th, Ra, Pb, and Be. The residue of a 3 L, standard superficial freshwater, evaporated sample was analyzed in a high efficiency, low background Ge detector, which leads to a sufficient precision for most environmental studies. The method has been applied to rain, river, and lake waters to study the impact of disused uranium mine water inputs on the [SUP238]U, [SUP228-234]Th, [SUP226-228]Ra, [SUP210]pb, and [SUP7]Be river and lake contents in the U mining area of Limoges (France). [ABSTRACT FROM AUTHOR]

Abstract: Dinoflagellate cyst assemblages were analysed in four short sediment cores collected in the south Basin of the Caspian Sea for assessing environmental changes over the last few millennia. Two of these cores were dated by radionuclides. The sedimentation rate of one of them was very high, in the order of 20 mm per year. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the concentration of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, it became clear that this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last decades, we show that the main forcing for the recent increase of L. machaerophorum percentages and concentration is global climate change, especially sea surface temperature increase. Sea level fluctuations likely only have a minor impact. We argue that the recent increase in L. machaerophorum indicates that the Caspian Sea clearly is in the Anthropocene. [Copyright &y& Elsevier]

Analysis of 60Co traces in the matrix steel has recently gained in importance. This paper deals with the low-level γ-ray spectrometry measurements that were part of a recent German survey aiming at determining the present levels of artificial radionuclides in commercial steel. Specific 60Co activities in the order of 10-5 Bq g-1 were measured. To show equivalence in these measurements, a comparison exercise of European underground laboratories has been carried out, additionally. [Copyright &y& Elsevier]

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas.By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes γ-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring 60Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from 60Co activity is in agreement with previous measurements using the short-lived radionuclides 51Cr and 59Fe. Limits on contamination of the samples with 60Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using 60Co activation. [Copyright &y& Elsevier]