カテゴリー「ecology・environment」
Title: MUD: a Model to investigate the migration of 137Cs in the Urban environment and Drainage and sewage treatment systems.
Author: Gallego, Eduardo.
Reference: Journal of Environmental Radioactivity. Oct2005, Vol. 85 Issue 2/3, p247-264. 18p.
DOI: 10.1016/j.jenvrad.2004.10.017.
Keywords: Technetium-99; Chernobyl fallout; Organic soil; Plants of the understorey vegetation
Abstract: A model is presented for the migration of137Cs in the urban environment, including the drainage systems and the sewage treatment plants, with flexibility to be adapted to different configurations common in urban areas. The dynamics of137Cs is simulated both under natural evolution and in case of forced decontamination, which can have a direct impact on the radioactivity going to sewers. The model assesses the activity concentrated in sewage sludge and that discharged with the treated or untreated effluent to the receiving watercourse. Tests made for two post-Chernobyl contamination scenarios in Sweden show differences between model predictions and observed results within the range of the experimental uncertainties. An uncertainty and sensitivity analysis of the main model parameters indicates that some parameters may have a significant influence on the results of the model. Moreover, the model uncertainty is driven by a few parameters; therefore, additional research could be necessary into these parameters, aiming at simplifying the model without losing its predictive power.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X05002201
Title: Separation of Tc-99 in soil and plant samples collected around the Chernobyl reactor using a Tc-selective chromatographic resin and determination of the nuclide by ICP-MS
Author: Uchida, S.; Tagami, K.; Ruhm, W.; Steiner, M.; Wirth, E.
Reference: Applied Radiation and Isotopes, July-Aug. 2000, vol.53, no.1-2, pp. 69-73
DOI: http://dx.doi.org/10.1016/S0969-8043(00)00112-3
Keywords: Technetium-99; Chernobyl fallout; Organic soil; Plants of the understorey vegetation
Abstract: Technetium (Tc) is known to have high mobility in a soil–water system and also high bioavailability for plants, because the most stable form of Tc in natural surface environment is thought to be TcO−4 which is highly soluble. The chemical form of Tc, however, changes with environmental conditions. Thus, it is necessary, for realistic assessment, to obtain transfer parameters, such as transfer factors, under natural conditions. However, it is difficult to obtain these parameters using global fallout in actual fields due to its low concentration. In this study, concentrations in surface soil and plant leaf samples collected from forest sites within the 30-km zone around the Chernobyl reactor were measured for the first time. In the case of soil samples, a simple and rapid analytical method for determination of is used which consists of volatilizing and trapping Tc in a combustion apparatus, purifying the Tc with an extraction chromatographic resin, and measuring it by inductively coupled plasma mass spectrometry (ICP-MS). For plant samples, a wet digestion method in combination with the resin is applied and the is measured by ICP-MS. Concentrations of in organic soil samples and leaves of strawberry (Fragaria vesca) range from 1.1–14.8 Bq kg−1 dry weight and 0.2–6.0 Bq kg−1 dry weight, respectively. Our results indicate that soil-to-plant transfer factors for Tc are similar to those for Cs.
URL: http://www.sciencedirect.com/science/article/pii/S0969804300001123
Title: Transfer and behaviour of 137Cs in two Finnish lakes and their catchments
Author: Saxén, Ritva; Ilus, Erkki.
Reference: Science of the Total Environment. May2008, Vol. 394 Issue 2/3, p349-360. 12p.
DOI: 10.1016/j.scitotenv.2008.01.048.
Keywords: Caesium-137; Chernobyl fallout; Freshwater fish; Aquatic plants; Lake sediments; Mushrooms
Abstract: The long-term behaviour of 137Cs was studied in two freshwater ecosystems in southern Finland in an area most loaded by the Chernobyl fallout in 1986. Samples were taken from water, sediments, aquatic plants and fish in the lakes and from soil, mushrooms and seed plants in the catchments. The activity concentrations of 137Cs in fish have remained at a relatively high level and decreased much more slowly in these two lakes than in other lakes studied by us. One reason for the continuously high concentrations in fish is evidently the prolonged stay of caesium at a relatively high level in the water of these lakes, which is associated with a slow sedimentation rate. The hydrographical properties of the lakes, i.e. the oligotrophic character associated with a deficiency of potassium in water and a low pH are other reasons for the effective uptake and long retention time of 137Cs in fish. The effect of humic substances on the uptake and delay of caesium in fish could not be proved clearly in this study. The swampy soil type of the catchment associated with a more oligotrophic status and lower pH of the water in Lake Siikajärvi explain at least partly the difference in activity concentrations and transfer of 137Cs between the two lakes studied. This refers to the higher transfer from the catchment to the lake and the higher uptake of 137Cs by fish and other biota in Lake Siikajärvi than in Lake Vehkajärvi. Perch and pike were more efficient accumulators of caesium than the best indicators among the aquatic plants. In the terrestrial environment, caesium was most effectively accumulated by mushrooms.
URL: http://www.sciencedirect.com/science/article/pii/S0048969708000971
Title: Monitoring and assessment of radionuclide discharges from Temelín Nuclear Power Plant into the Vltava River (Czech Republic)
Author: Hanslík, Eduard; Ivanovová, Diana; Juranová, Eva; Šimonek, Pavel; Jedináková-Křížová, Věra.
Reference: Journal of Environmental Radioactivity. Feb2009, Vol. 100 Issue 2, p131-138. 8p.
doi: http://dx.doi.org/10.1016/j.jenvrad.2008.11.001
Keywords: Tritium; Activation and fission products; Radioactive wastewater; Surface water; Sediment; Environmental half-life; Ecological half-time
Abstract: The paper summarizes impacts of the Temelín Nuclear Power Plant (NPP) on the Vltava and Labe River basins. The study is based on the results of long-term monitoring carried out before the plant operation (1989–2000), and subsequently during the plant operation (2001–2005). In the first period, the main objective was to determine background radionuclide levels remaining in the environment after global fallout and due to the Chernobyl accident. A decrease in the concentrations of 90Sr, 134Cs and 137Cs, which was observed before the plant operation, continued also during the subsequent period. Apart from tritium, the results of the observation did not indicate any impacts of the plant on the concentrations of activation and fission products in the hydrosphere. The annual average tritium concentrations in the Vltava River were in agreement with predicted values. The maximum annual average tritium concentration (13.5 Bq L−1) was observed in 2004 downstream from the wastewater discharge in the Vltava River at Solenice. Estimated radiation doses for adults due to intakes of river water as drinking water contaminated by tritium are below 0.1 μSv y−1.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X08001963
Title: High levels of fluctuating asymmetry in populations of Apodemus flavicollis from the most contaminated areas in Chornobyl
Author: Taras K Oleksyk, James M Novak, James R Purdue, Sergiy P Gashchak, Michael H Smith
Reference: Journal of Environmental Radioactivity. Mar2004, Vol. 73 Issue 1, p1. 20p.
doi: http://dx.doi.org/10.1016/j.jenvrad.2003.07.001
Keywords: Radiocesium; 137Cs; Apodemus flavicollis; Chornobyl; Chernobyl; Size; Shape; Fluctuating asymmetry; Directional asymmetry; Geometric morphometrics
Abstract: Random deviations from the perfect symmetry of normally bilaterally symmetrical characters for an individual with a given genotype occur during individual development due to the influence of multiple environmental factors. Fluctuating asymmetry (FA) is often used as a measure of developmental instability, and can be estimated as the variance of the distribution of differences between the left and right sides. We addressed the question of whether levels of FA were elevated in radioactively contaminated populations living around Chornobyl compared to those in reference populations of the yellow-necked mouse (Apodemus flavicollis). In addition, we studied amounts of directional asymmetry (DA) when one side is larger than the other on average. There was a significant difference among populations, including reference populations, in the amount of both FA and DA. A higher level of FA was documented for the contaminated populations in close proximity to the failed Chornobyl reactor for both the asymmetry of size and shape. The FAs of size and shape were highest in populations from the most contaminated locations in the Chornobyl exclusion zone. Although the directional asymmetry of shape was also highest in the contaminated populations, it was not significantly different from those in most of the reference populations. Populations from less contaminated areas inside the Chornobyl exclusion zone did not express FA values different from those of the reference populations outside the affected area. FA of skulls of A. flavicollis may indicate the degree to which the level of radioactive contamination affects the development of animals at Chornobyl. However, the mechanisms leading to these effects are not clear and probably vary from population to population. There were significant correlations between the overall right to left differences for the Procrustes aligned shape configurations, centroid sizes, and intramuscular 137Cs. Detectable effects of radiation on developmental stability probably start to occur between 0.132 and 0.297 μGy/h.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X03002224
Title: Radioactive contamination in the marine environment adjacent to the outfall of the radioactive waste treatment plant at ATOMFLOT, northern Russia
Author: Brown, J.E.; Nikitin, A.; Valetova, N.K.; Chumichev, V.B.; Katrich, I.Y.; Berezhnoy, V.I.; Pegoev, N.N.; Kabanov, A.I.; Pichugin, S.N.; Vopiyashin, Y.Y.; Lind, B.; Grottheim, S.; Sickel, M.; Strand, P.
Reference: Journal of Environmental Radioactivity, 2002, vol.61, no.1, pp. 111-31
doi: http://dx.doi.org/10.1016/S0265-931X(01)00121-7
Keywords: Radionuclides; Marine; Kola Bay; ATOMFLOT
Abstract: RTP “ATOMFLOT” is a civilian nuclear icebreaker base located on the Kola Bay of northwest Russia. The objectives of this study were to determine the distributions of man-made radionuclides in the marine environment adjacent to the base, to explain the form of the distributions in sediments and to derive information concerning the fate of radionuclides discharged from ATOMFLOT. Mean activity concentrations (d.w.) for surface sediment, of 63 Bq kg−1137Cs, 5.8 Bq kg−190Sr and 0.45 Bq kg−1239,240Pu were measured. Filtered seawater activity levels were in the range of 3–6.9 Bq m−3137Cs, 2.0–11.2 Bq m−390Sr, and 16–40 mBq m−3, 239,240Pu. Short-lived radionuclides were present at sediment depths in excess of 10 cm indicating a high degree of sediment mixing. Correlations of radionuclide activity concentrations with grain-size appear to be absent; instead, the presence of relatively contaminated sediment appears to be related to the existence of radioactive particles.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X01001217
Title: Protection of Melanized Cryptococcus neoformans from Lethal Dose Gamma Irradiation Involves Changes in Melanin’s Chemical Structure and Paramagnetism
Author: Khajo, Abdelahad; Bryan, Ruth A.; Friedman, Matthew; Burger, Richard M.; Levitsky, Yan; Casadevall, Arturo; Magliozzo, Richard S.; Dadachova, Ekaterina.
Reference: PLoS ONE. 2011, Vol. 6 Issue 9, p1-8. 8p.
doi: 10.1371/journal.pone.0025092.
Keywords: *CRYPTOCOCCUS neoformans*MELANINS*CHEMICAL structure*PARAMAGNETISM*HYDROXYL group*BACTERIAL cells*FUNGUS-bacterium relationships
Abstract: Certain fungi thrive in highly radioactive environments including the defunct Chernobyl nuclear reactor. Cryptococcus neoformans (C. neoformans), which uses L-3,4-dihydroxyphenylalanine (L-DOPA) to produce melanin, was used here to investigate how gamma radiation under aqueous aerobic conditions affects the properties of melanin, with the aim of gaining insight into its radioprotective role. Exposure of melanized fungal cell in aqueous suspensions to doses of γ-radiation capable of killing 50 to 80% of the cells did not lead to a detectable loss of melanin integrity according to EPR spectra of melanin radicals. Moreover, upon UV-visible (Xe-lamp) illumination of melanized cells, the increase in radical population was unchanged after γ-irradiation. Gamma-irradiation of frozen cell suspensions and storage of samples for several days at 77 K however, produced melanin modification noted by a reduced radical population and reduced photoresponse. More direct evidence for structural modification of melanin came from the detection of soluble products with absorbance maxima near 260 nm in supernatants collected after γ-irradiation of cells and cell-free melanin. These products, which include thiobarbituric acid (TBA)-reactive aldehydes, were also generated by Fenton reagent treatment of cells and cell-free melanin. In an assay of melanin integrity based on the metal (Bi+3) binding capacity of cells, no detectable loss in binding was detected after γ-irradiation. Our results show that melanin in C. neoformans cells is susceptible to some damage by hydroxyl radical formed in lethal radioactive aqueous environments and serves a protective role in melanized fungi that involves sacrificial breakdown.
URL: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025092
Title: Fungi and ionizing radiation from radionuclides
Author: Dighton, John; Tugay, Tatyana; Zhdanova, Nelli.
Reference: FEMS Microbiology Letters. Apr2008, Vol. 281 Issue 2, p109-120. 12p. 1
doi: 10.1111/j.1574-6968.2008.01076.x
Keywords: melanin, micro-fungi, mycorrhizae, radioadaptive properties, radionuclides, remediation
Abstract: Radionuclides in the environment are one of the major concerns to human health and ecotoxicology. The explosion at the Chernobyl nuclear power plant renewed interest in the role played by fungi in mediating radionuclide movement in ecosystems. As a result of these studies, our knowledge of the importance of fungi, especially in their mycorrhizal habit, in long-term accumulation of radionuclides, transfer up the food chain and regulation of accumulation by their host plants was increased. Micro-fungi have been found to be highly resilient to exposure to ionizing radiation, with fungi having been isolated from within and around the Chernobyl plant. Radioresistance of some fungal species has been linked to the presence of melanin, which has been shown to have emerging properties of acting as an energy transporter for metabolism and has been implicated in enhancing hyphal growth and directed growth of sensitized hyphae towards sources of radiation. Using this recently acquired knowledge, we may be in a better position to suggest the use of fungi in bioremediation of radioactively contaminated sites and cleanup of industrial effluent
URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6968.2008.01076.x/full
Title: 137Cs and 40K activity concentration measurements and elemental analysis in lichen samples collected from the Giresun province of northeastern Turkey
Author: Celik, Necati; Cevik, Ugur; Celik, Ahmet; Koz, Bahadir.
Reference: Isotopes in Environmental & Health Studies. Sep2008, Vol. 44 Issue 3, p315-323. 9p. 3
doi: 10.1080/10256010802310077
Keywords: cesium-137, elemental analysis, lichens, natural radioactivity, potassium-40, Turkey
Abstract: About 21 years after the Chernobyl accident, 137Cs and 40K activity concentration measurements using gamma-ray spectroscopy and elemental analysis using energy dispersive X-ray spectroscopy were performed in five different lichen species collected from the Giresun province of northeastern Turkey. Being a symbiosis of algae and fungi, lichens are mostly used for environmental measurements since the fungal partner is responsible for the uptake of necessary nutrients or harmful substances, such as heavy metals of radionuclides. The gamma activity results showed that 137Cs, an artificial radionuclide released from the Chernobyl power plant accident, is still eminent in the environment of the province. The mean activity concentrations of 137Cs and 40K ranged from 24 to 254 with the mean value of 102 Bq kg−1 and from 345 to 2103 with the mean value of 1143 Bq kg−1 in dry weight. The results of the elemental analyses showed potassium, calcium, titanium, iron, tin, and barium in different concentrations.
URL: http://www.tandfonline.com/doi/abs/10.1080/10256010802310077
Title: Concentration of radionuclides in hydrosphere affected by Temelín Nuclear Power Plant in Czech Republic.
Author: Hanslík, E.; Ivanovová, D.; Jedináková-Křížová, V.; Juranová, E.; Šimonek, P.
Reference: Journal of Environmental Radioactivity. Jul2009, Vol. 100 Issue 7, p558-563.
doi:10.1016/j.jenvrad.2009.03.020.
Keywords: Activation and fission products; Radioactive wastewater; Sediments; Surface water; Temelín NPP; Tritium
Abstract: The paper presents results of a long-term field study of the possible impact of Temelín NPP on the Vltava and Elbe Rivers. The study was divided into 2 stages: before and after the operation of the NPP. The main goal of the investigation before the operation (1989–2000) was to determine the background levels of radionuclides resulting from the tests of nuclear weapons and the Chernobyl accident for different components of the environment. The paper discusses also the risk of a river radioactive contamination due to the tritium discharges in wastewater from Temelín NPP. During the operation period of 2001–2006, the results of the monitoring did not detect any impact of Temelín NPP on the concentrations of activation and fission products in the hydrosphere, apart from tritium. The annual average tritium concentrations in the Vltava River correspond with the previously calculated predictions for the conditions of the average and minimum guaranteed flows. The maximum concentration of tritium of 26.6 Bq/l in Vltava River at Prague was observed after dry period in 2003.
URL: http://www.sciencedirect.com/science/article/pii/S0265931X0900071X
