RESUMEN
Mosses are frequently used as biomonitors for trace element pollution in the aquatic environment. The purpose of this study was to assess their usefulness as a tool in monitoring and in regional surveys of radioactive contamination. Specimens of the aquatic mosses, Fontinalis antipyretica and F. dalecarlica, were transplanted from non-contaminated areas to streams and rivers in the Norwegian Jotunheimen Mountains and neighbouring lowland areas that had received radioactive fallout after the Chernobyl accident. Equilibrium concentrations of 137Cs in the exposed mosses were reached after a few weeks. Two series from 20 streams in 1994 and 1996 show linear correlations between activities in water and moss samples and biomagnification ratios of 10(4) - 10(5). We conclude that mosses are better suited for monitoring purposes than water samples, because they provide values integrated over weeks while the radioactivity in surface waters can be subject to rapid variations according to hydrological events. The activity concentrations in aquatic mosses can be easily measured with good precision even when aqueous concentrations are below the limit of detection. Use of aquatic mosses also reduces the logistic problems of transporting large volumes of water, especially in areas inaccessible by road.
Asunto(s)
Bryopsida/química , Monitoreo del Ambiente/métodos , Ceniza Radiactiva/análisis , Liberación de Radiactividad Peligrosa , Contaminantes Radiactivos/análisis , Radioisótopos de Cesio/análisis , Noruega , Centrales Eléctricas , Contaminantes Radiactivos/farmacocinética , Sensibilidad y Especificidad , UcraniaRESUMEN
The lack of a suitable tracer has severely limited the use of radioisotope tracer experiments in environmental and biological studies on aluminium. The only aluminium radioisotope with a half-life greater than 10 min is the long-lived positron emitter 26Al (t1/2 7.2 x 10(5) years). The exposure of this nuclide and the difficulty in attaining sufficiently low determination limits with standard radioanalytical techniques have restricted its application as a radioactive tracer. The development of a simple method for the routine determination of 26Al using Cerenkov counting and a Quantalus 1220 low-level liquid scintillation spectrometer is reported. For a 300 min counting time, determination limits of about 60 mBq in water samples and 120 mBq in biological (fish gill) samples can be attained. With these levels of determination, the use of 26Al as a tracer is a viable technique for the study of aluminium in environmental and biological systems.
Asunto(s)
Aluminio/análisis , Contaminantes Radiactivos del Agua/análisis , Animales , Peces , Branquias/química , Radioisótopos/análisis , Conteo por CintilaciónRESUMEN
A radiochemical method for the simultaneous determination of 239Pu + 240Pu and 241Pu in environmental samples has been developed. In the course of the analysis a 236Pu tracer was used for estimating the chemical yield of plutonium isotopes. After suitable pre-treatment of the sample, the plutonium nuclides in solution were coprecipitated with iron(III) hydroxide and calcium oxalate and isolated further from impurities and interfering radionuclides by means of anion-exchange chromatography. Plutonium isotopes in the eluate (NH4I-HCI) were converted into nitrate form and then extracted with 20 ml of 5% bis(2-ethylhexyl) hydrogen phosphate extractive cocktail. The final organic solution was measured spectrometrically using an ultra-low-level liquid scintillation spectrometer, Quantulus (LKB, 1220 Wallac). The chemical yields of plutonium range from 25 to 50% for 100 I of sea-water and 30 to 60% for 40 g of dried soil sample. The counting efficiencies are nearly 100% for 239Pu + 240Pu and 48.8% for 241Pu, respectively. The detection limits were estimated to be 0.20 mBq for 239Pu + 240Pu and 2.2 mBq for 241Pu, respectively. The proposed procedure has been tested for the simultaneous determination of 239Pu + 240Pu and 241Pu in sea-water (Irish Sea, North Sea) and soils (Cumbrian coast, UK; Byelorussia, USSR).
Asunto(s)
Plutonio/análisis , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisis , Europa (Continente) , Conteo por Cintilación , Agua de Mar , U.R.S.S. , Reino UnidoRESUMEN
The amounts of 137Cs and 90Sr have been determined in the inflows and outflows of the Norwegian sub-alpine lake, Ovre Heimdalsvatn, in March/April during the period of ice-cover, when discharge is extremely stable. The lake is situated in an area contaminated by Chernobyl fallout. The transported course particulate plant material has been collected in traps; the particles and colloids have been removed from water samples by cross-flow ultrafiltration. On the basis of radionuclide inputs and outputs, lake budget calculations have been made for 137Cs and 90Sr during the period of ice-cover. Daily transport of radionuclides is considerably less than that observed during the spring snowmelt period when discharges are high. Size distribution patterns of Cs and Sr observed during winter are compared with previously published data from the same lake during the spring spate. The retention of 137Cs is similar in winter and spring, but retention of 90Sr is greater in winter.
Asunto(s)
Accidentes , Radioisótopos de Cesio/análisis , Reactores Nucleares , Ceniza Radiactiva , Radioisótopos de Estroncio/análisis , Contaminantes Radiactivos del Agua/análisis , Clima Frío , Geografía , Noruega , Estaciones del Año , UcraniaRESUMEN
Different approaches to the estimation of radiocaesium deposition on different types of indigenous mountain pastures have been examined. In situ gamma spectrometric measurements performed using a portable multi-channel analyser (3 x 3 in Nal detector) with the detector placed on the ground, on a tripod at a height of 100 cm above the ground or fastened to a rucksack frame 90 cm above the ground were compared with conventional soil sampling. Field gamma-ray measurements in connection with soil sampling appear to be a promising tool for estimates of deposition on mineral soils in areas with different topography and vegetation.
Asunto(s)
Accidentes , Radioisótopos de Cesio/análisis , Reactores Nucleares , Plantas/química , Ceniza Radiactiva/análisis , Contaminantes Radiactivos del Suelo/análisis , Altitud , Alimentación Animal , Geografía , Noruega , Poaceae/química , UcraniaRESUMEN
Results are presented from an experiment designed to investigate the deposition of Al species onto fish gills following the mixing of limed and acidic natural waters. The natural waters were labelled with 26Al and the distribution between high and low molecular weight forms was determined by ultrafiltration of water samples. In labelled acidic waters, the 26Al was present predominantly in low molecular weight forms, whereas in labelled limed waters the major fraction of 26Al was present in a high molecular weight form. In mixing experiments, 26Al was only detectable on fish gills when the 26Al was initially present in a low molecular weight form (i.e., in labelled acidic waters). Aluminium-26 was not detected on the gills of fish exposed to labelled limed waters. These results support the hypothesis that Al on fish gills arises from polymerization of low molecular weight species and that, within mixing zones, the high molecular weight species do not play a significant role in the precipitation of Al onto the gill surface.