Radioecological Research Research Articles

Radioecological Research on the Marine Environment Facing the Italian Base in Antarctica (1989–91)

Abstract The results of the analysis of both natural (Th-232, U-238 and K-40) and artificial (Cs-137) radioactivity contained in samples collected during the 1989–90 and 1990–91 PNRA Scientific Campaigns in the Terra Nova Bay (Ross Sea) marine ecosystem, are presented in this paper. The data refers to samples of sea water, pack water, sediments and organisms belonging to demersal ichthyofauna (Pagothenia bernacchii, Chionodraco hamatus) and soft bottom macrofauna (Adamussium colbecki) collected in different coastal and off shore stations of the area investigated. Some sea water samples collected on the way to subAntarctic areas were also considered. The radiocontamination detected in sediments was correlated to the quantities of organic matter, organic carbon and nitrogen contained in the samples. Additionally, Cs-137 concentration factors were calculated for the different biological specimens and their anatomical components. Data values, with special consideration for anthropogenic Cs-137, are compared to results obtained from similar matrixes collected in the Northern Hemisphere in temperate waters before and after the accident at the Chernobyl nuclear plant.

Development of highly sensitive techniques for determination of concentrations of fission materials in water media using thin-layer inorganic sorbents and plastic track detectors

A technique for determining the uranium concentration in the VVER-1000 primary coolant and natural fresh water was developed. Thin-layer inorganic sorbents on Ti and Ce hydroxides (thickness being tens of μg cm −2 ) were used for increasing the uranium concentration. After exposure in the experimental solution, thin-layer inorganic sorbents were irradiated by thermal neutrons when positioned in close contact with plastic track detectors; the latter were then etched electrochemically. A Lavsan film, 180 μm thick, was used as a detector for fission fragments. Detection sensitivity for uranium in ammonia-boron-potassium solution and distillate is a hundred or a thousand times higher than for the case of the track detector irradiated by neutrons directly in the solution. A detection limit for uranium in solutions is no worse than 3 × 10 −12 g cm −3 . It is defined, mainly, by a natural contamination of the sorbent by uranium. High sensitivity, a low detection limit, and simplicity of the technique in practice make it feasible for solving the problems of nuclear reactor radiation safety, radio-ecology and other research fields.

Development of highly sensitive techniques for determination of concentrations of fission materials in water media using thin-layer inorganic sorbents and plastic track detectors

A technique for determining the uranium concentration in the VVER-1000 primary coolant and natural fresh water was developed. Thin-layer inorganic sorbents on Ti and Ce hydroxides (thickness being tens of μg cm −2) were used for increasing the uranium concentration. After exposure in the experimental solution, thin-layer inorganic sorbents were irradiated by thermal neutrons when positioned in close contact with plastic track detectors; the latter were then etched electrochemically. A Lavsan film, 180 μm thick, was used as a detector for fission fragments. Detection sensitivity for uranium in ammonia-boron-potassium solution and distillate is a hundred or a thousand times higher than for the case of the track detector irradiated by neutrons directly in the solution. A detection limit for uranium in solutions is no worse than 3 × 10 −12 g cm −3. It is defined, mainly, by a natural contamination of the sorbent by uranium. High sensitivity, a low detection limit, and simplicity of the technique in practice make it feasible for solving the problems of nuclear reactor radiation safety, radio-ecology and other research fields.

Investigations of radiocaesium in the natural terrestrial environment in Norway following the Chernobyl accident.

Radioactive fallout from the Chernobyl accident affected parts of central Norway to a considerable extent, in particular the 134Cs+137Cs deposition had a significant impact on the natural environment. When this became apparent, a comprehensive radioecological research programme was initiated in order to study the behaviour of radiocaesium in boreal and alpine ecosystems, with emphasis on food-chains leading to exposure of species used for human consumption, i.e., reindeer and freshwater fish. In this paper results from the terrestrial part of this research programme during the period 1986-1990 are presented. The work was mainly confined to the mountain areas of Dovre and Rondane. Parallel studies were performed in eutrophic and strongly oligotrophic communities. The influence of local variations in topography and microclimate on the observed radiocaesium levels in topsoils, lichens and vascular plants was studied in detail. Currently a significant re-distribution of radiocaesium from the originally strongly exposed surfaces to those that were less exposed is observed. In the soil, radiocaesium is strongly retained in the litter and raw humus layers. Current levels in lichens are 1-2 orders of magnitude higher than in vascular plants. This strongly affects the seasonal variation of radiocaesium in reindeer, showing winter maxima of about 5 times higher than the August levels. The radiocaesium levels in reindeer showed a decline of approximately a factor of 3 during the period 1987-1990. Other animal species studied in the programme exhibited substantially lower radiocaesium levels than reindeer, but a considerable interspecies variation was observed.

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A perspective on radioecological research

Radioecology began as an application of the concepts of the science of ecology to the problems of the new science of health physics - itself a product of the atomic age. The testing of atomic weapons created a need to understand the behaviour of radionuclides in the environment together with the necessity for developing data on the effects of ionizing radiation. Much current radioecological research has been directed toward enhancing our knowledge of radionuclide transport in major environments in order to derive transfer coefficients for radiological dose assessment codes. Most current radioecological research is centred on operating nuclear installations which provide major opportunities for developing new insights on nuclide behaviour and for training students. This type of effort should continue to be encouraged in the future because of the distinct advantages offered by such locations. Future radioecological research will be needed for predicting exposures resulting from the transport of radionuclides in agricultural food chains. Model validation using field studies and experiments is another pressing area of radioecology. There is a continuing need for data on the long-term impact of chronic low level ionizing radiation on species and populations in natural systems in relation to such problems as radioactive waste disposal. Lastly, there is an opportunity for the continuing use of radioisotopes as tools for research in basic ecology and for attacking non-radioactive pollution problems.

放射性汚染海水の凝集沈殿処理 ＩＩ 実際の処理

Low-level radioactive contaminated sea water containing 137Cs, 60Co and 144Ce, of an amount of 64m3, brought from the Marine Radioecological Research Station of the National Institute of Radiological Sciences to the Tokai Establishment of the Japan Atomic Energy Research Institute, was treated with two-stage flocculation. The first stage of the flocculation was performed to remove 137Cs with copper ferrocyanide floc, and the ensuing second stage was applied to remove 60Co and 144Ce with calcium phosphate floc in alkaline solution.The results obtained revealed that the radioactive contamination was substantially reduced by the first-stage flocculation, while the second stage further lowered it to a level amply meeting expectations. As a result of the two-stage flocculation, the overall decontamination factor was indicated to be approximately 10. The sludge remaining from the flocculation was dewatered to 90% water content under reduced pressure. Then for the purpose of storage, the product was solidified with cement in a steel container, of a volume of 200l.

A utility sponsored environmental surveillance and radioecological research program for a coastal nuclear power plant.

A utility sponsored environmental surveillance and radioecological research program for a coastal nuclear power plant. C E Roessler, W E Bolch, J F Gamble, and W B Johnson, JrCopyRight https://doi.org/10.2105/AJPH.62.10.1379 Published Online: October 07, 2011

Radiolabeling Dermacentor variabilis with strontium-90 and strontium-90 plus carbon-14 mixtures.

The feasibility of radiolabeling larval American dog ticks, Dermacentor variabilis (Say) with strontium-90 (90Sr) is demonstrated. The radioisotope was administered in inorganic form by inoculation of procreant females. Transovarial transfer to larval progeny resulted in sufficient radioactivity to permit easy detection of labeling in individual larvae. Double labeling of D. variabilis with both carbon-14 (14C) and 90Sr was done by inoculations of mixtures of 14C glucose and inorganic 90Sr into the engorged parents. Detection of these double-labeled ticks and discrimination of such individuals from either 14C- or 90Sr- labeled ticks was done with the aid of a 2-channel liquid scintillation detector. The advantages of increasing the variety of radioisotope labels available for radioecological research with ticks are discussed.