Real-time monitoring data for real-time multi-model validation: coupling ENSEMBLE and EURDEP

The ENSEMBLE system has been considerably expanded and improved. The system that allows the real-time collection of atmospheric dispersion forecasts their real-time consultation and ensemble dispersion analysis has been coupled with the EUropean Radiological Data Exchange Platform (EURDEP) for the acquisition of real-time monitoring data on environmental (mainly in air) radiological measurements. This paper explains how the coupling has been realized and presents the potentials of this unique system that is presently in use in more than 25 countries around the world.     

Low level radioactivity measurements with phoswich detectors using coincident techniques and digital pulse processing analysis

A new system has been developed for the detection of low radioactivity levels of fission products and actinides using coincidence techniques. The device combines a phoswich detector for alpha/beta/gamma-ray recognition with a fast digital card for electronic pulse analysis. The phoswich can be used in a coincident mode by identifying the composed signal produced by the simultaneous detection of alpha/beta particles and X-rays/gamma particles. The technique of coincidences with phoswich detectors was proposed recently to verify the Nuclear Test Ban Treaty (NTBT) which established the necessity of monitoring low levels of gaseous fission products produced by underground nuclear explosions. With the device proposed here it is possible to identify the coincidence events and determine the energy and type of coincident particles. The sensitivity of the system has been improved by employing liquid scintillators and a high resolution low energy germanium detector. In this case it is possible to identify simultaneously by alpha/gamma coincidence transuranic nuclides present in environmental samples without necessity of performing radiochemical separation. The minimum detectable activity was estimated to be 0.01 Bq kg(-1) for 0.1 kg of soil and 1000 min counting.     

Characterization of radioactive particles from the Palomares accident

As a consequence of the nuclear accident that took place in Palomares (Almería, Spain) more than 40 years ago, actinides contamination is present in the area nowadays. Previous investigations performed with soil samples collected in different locations of Palomares indicate that the contamination in the area is highly inhomogeneous, suggesting the existence of radioactive particles, thus hindering the evaluation of the radiological situation. This work presents the methodology used for the location of the radioactive particles in the field and their isolation in the laboratory for further speciation and characterization studies. Colour pictures, electron microscopy images and EDX analyses show that most of the studied particles present a granular appearance with a variable grain size and a high fragmentation tendency, being plutonium and uranium the most abundant nuclear elements. Radiochemical determinations and activity isotopic ratios prove that the nuclear material is aged weapon grade plutonium arising from the Palomares accident.     

Accumulation of (137)Cs in Brazilian soils and its transfer to plants under different climatic conditions

The spatial distribution and behaviour of the global fallout (137)Cs in the tropical, subtropical and equatorial soil-plant systems were investigated at several upland sites in Brazil selected according to their climate characteristics, and to the agricultural importance. To determine the (137)Cs deposition density, undisturbed soil profiles were taken from 23 environments situated between the latitudes of 02 degrees N and 30 degrees S. Sampling sites located along to the equator exhibited (137)Cs deposition densities with an average value of 219Bqm(-2). Extremely low deposition densities of 1.3Bqm(-2) were found in the Amazon region. In contrast, the southern part of Brazil, located between latitudes of 20 degrees S and 34 degrees S, exhibited considerably higher deposition densities ranging from 140Bqm(-2) to 1620Bqm(-2). To examine the (137)Cs soil-to-plant transfer in the Brazilian agricultural products, 29 mainly tropical plant species, and corresponding soil samples were collected at 43 sampling locations in nine federal states of Brazil. Values of the (137)Cs concentration factor plant/soil exhibited a large range from 0.020 (beans) to 6.2 (cassava). Samples of some plant species originated from different collecting areas showed different concentration factors. The (137)Cs content of some plants collected was not measurable due to a very low (137)Cs concentration level found in the upper layers of the incremental soils. Globally, the soil-to-plant transfer of (137)Cs can be described by a logarithmic normal distribution with a geometric mean of 0.3 and a geometric standard deviation of 3.9.     

Role and influence of mycorrhizal fungi on radiocesium accumulation by plants

This review summarizes current knowledge on the contribution of mycorrhizal fungi to radiocesium immobilization and plant accumulation. These root symbionts develop extended hyphae in soils and readily contribute to the soil-to-plant transfer of some nutrients. Available data show that ecto-mycorrhizal (ECM) fungi can accumulate high concentration of radiocesium in their extraradical phase while radiocesium uptake and accumulation by arbuscular mycorrhizal (AM) fungi is limited. Yet, both ECM and AM fungi can transport radiocesium to their host plants, but this transport is low. In addition, mycorrhizal fungi could thus either store radiocesium in their intraradical phase or limit its root-to-shoot translocation. The review discusses the impact of soil characteristics, and fungal and plant transporters on radiocesium uptake and accumulation in plants, as well as the potential role of mycorrhizal fungi in phytoremediation strategies.     

Loft features reveal the functioning of the young pigeon’s navigational system

It is thought that young homing pigeons are able to use information acquired en route for their initial homeward orientation. However, the cues involved and mechanisms utilised are under discussion. Blocking light-dependent route-specific information during the first leg of an outward journey detour, together with analysis of pigeons that were raised under different loft conditions, allowed us to correctly evaluate the functioning of this mechanism and, more generally, the navigational map of birds. Pigeons from the same stock were raised and kept in two different lofts. The birds in the experimental groups were transported to the release sites via detours, and light-dependent information was denied during the first half of the outward journey (no compass information was available). Control birds were transported by the most direct route and had access to all available information. In general, the results showed that the low-loft birds preferred to use magnetic compass cues, whereas the high-loft birds preferred to use navigational map cues to collect information of the first part of the outward journey. The impairments observed in the homing performances of the experimental groups highlight the reliability of information collected inside the map area. Relevant to an understanding of the route-reversal mechanism was the evidence that this mechanism is able to function in the absence of compass information (birds raised in a wind-exposed loft show a detour effect). In systems where directional information could be provided by multiple sources, processing and extracting accurate course trajectories through a common mechanism may prove more efficient and reliable.     

Breeding skylarks (Alauda arvensis) on organic and conventional arable farms in The Netherlands

The aim of this study was to analyse the effects of differences in cropping pattern between organic and conventional arable farms on the breeding activity of skylarks and to assess the effects of arable crop management on skylark nest survival. Skylark nest density was seven times higher on organic farms than on conventional farms (0.63 vs. 0.09 nest per 10 ha). Skylarks showed a strong preference for spring cereals, lucerne and grass leys, all of which were mainly or exclusively grown on organic farms. On organic farms nests were initiated during the entire breeding season, but on conventional farms no nesting activity was found during the peak of the season (early May to early June). On organic farms 27% of all nests was successful. Increasing the availability of suitable breeding habitat during the peak of the breeding season on conventional farms might provide one means of enhancing breeding skylark populations. On organic farms, crop management should focus on reducing nest loss due to farming operations.     

Increase in membrane thickness during development compensates for eggshell thinning due to calcium uptake by the embryo in falcons

We compared membrane thickness of fully developed eggs with those of non-developed eggs in different endangered falcon taxa. To our knowledge, membrane thickness variation during development has never been examined before in falcons or any other wild bird. Yet, the egg membrane constitutes an important protective barrier for the developing embryo. Because eggshell thinning is a general process that occurs during bird development, caused by calcium uptake by the embryo, eggs are expected to be less protected and vulnerable to breakage near the end of development. Thus, egg membranes could play an important protective role in the later stages of development by getting relatively thicker. We used linear mixed models to explore the variation in membrane thickness (n = 378 eggs) in relation to developmental stage, taxon, female age, mass and identity (73 females), egg-laying sequence (105 clutches) and the study zone. Our results are consistent with the prediction that egg membranes are thicker in fully developed eggs than in non-developed eggs, suggesting that the increase in membrane thickness during development may compensate for eggshell thinning. In addition, our data shown that thicker membranes are associated with larger, heavier and relatively wider eggs, as well as with eggs that had thinner eggshells. Egg-laying sequence, female age and the study zone did not explain the observed variation of membrane thickness in the falcon taxa studied. As we provide quantitative data on membrane thickness variation during development in falcons not subjected to contamination or food limitation (i.e. bred under captive conditions), our data may be used as a reference for studies on eggs from natural populations. Considering the large variation in membrane thickness and the multiple factors affecting on it and its importance in the protection of the embryo, we encourage other researchers to include measurements on membranes in studies exploring eggshell thickness variation.     

Model evaluation of different mechanisms driving freeze–thaw N2O emissions

N₂O emissions from soil contribute significantly to global warming. Pulse emissions of N₂O from soils during freeze-thawing were recently recognized as important atmospheric sources. In this modelling study we explore three different hypotheses for explaining freeze–thaw related N₂O emissions: (1) soil frost or snow cover may reduce gas diffusion and create anaerobic conditions that stimulate N₂O production via denitrification, (2) microbes that die of frost deliver easy decomposable organic carbon and nitrogen to the soil, which stimulates microbial growth and vigorous N₂O production during freeze–thaw, and (3) the enzyme nitrous oxide reductase, which is responsible for the reduction of N₂O to N₂ during denitrification, is more sensitive to low temperatures than other enzymes, so that N₂O becomes the dominating end-product of denitrification at low temperatures. These hypotheses were tested with a biogeochemical model that combines hydrology and physics calculations with a newly developed, parameter-poor biochemistry module. The model was first calibrated with field datasets on soil–atmosphere fluxes of N₂O, NO and CO₂ and soil NO₃ and NH₄ concentrations that were measured in a spruce forest in Southeast Germany in the years 1994–1997. Subsequently, additional model mechanisms were implemented that allow the model to describe the outlined mechanisms potentially driving freeze–thaw N₂O fluxes. After each implementation the model was recalibrated. We were able to mimic dimension and timing of high N₂O emissions when either one of the first two hypotheses were assumed, but found no confirmation for the third. The best model fit was achieved by combining hypothesis one and two, indicating that freeze–thaw N₂O emissions are not mono-causal.     

Suicidal behavior by motor vehicle collision

BACKGROUND: The ability for suicides of drivers to be disguised as traffic accidents raises the possibility that suicidal behaviors of this nature are far more prevalent than previously thought, potentially impacting health, road safety, and insurance companies. METHOD: Persons residing at the Gold Coast, Australia, identified as having a history of suicidal ideation and behaviors (n = 1,196), were sent a mail-out survey after their consent was obtained in initial telephone contact (CATI random digit-dialing). Among those responding, 412 had made suicide plans or arrangements and 228 suicide attempts. RESULTS: Of those who reported planning a suicide, 14.8% (19.1% of male planners and 11.8% of female planners) had conceived to have a motor vehicle "accident" (n = 61). Of all attempters, 8.3% (13.3% of male attempters) had previously attempted via motor vehicle collision (n = 19). All attempters reported having emotional or mental problems at the time of the event. Suicide planners were significantly more likely to be in full-time employment and have a partner and children compared with other planners. CONCLUSION: The study gives a rare insight into driver suicide plans and attempts, via a large-scale community survey, to provide the best opportunity of collecting unbiased data on the driver suicide behavior. Results suggest the use of this method, particularly in attempts made by males, may be underreported leading to inaccuracy of statistics. The motives behind choosing this method are somewhat different to those behind other methods, including financial benefits and eliminating stigma in the aftermath of a suicide.