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Sample records for natural radionuclides distribution

  1. Differences between the activity size distributions of the different natural radionuclide aerosols in outdoor air

    NASA Astrophysics Data System (ADS)

    Gründel, M.; Porstendörfer, J.

    The results of the activity size distribution of the short-lived ( 218Po, 214Bi/ 214Po) and long-lived ( 210Pb, 210Po) radon decay product aerosols, the thoron decay product aerosols ( 212Pb, 212Po) and 7Be of the outdoor atmosphere are presented. The results were obtained from measurements averaged over an extended period (4 weeks) and were carried out with a low-pressure On-Line Alpha Cascade Impactor (OLACI). The size distributions of the radionuclides were obtained from the same measurement run with the OLACI, so that the size classification technique and the atmospheric and weather conditions for all radionuclides were identical. This measurement technique made it possible to measure the correct differences between the size distributions of the different natural radionuclides in the environmental air. The differences between the activity size distributions of the long- and short-lived radionuclides could be explained by coagulation with aerosol particles of the atmosphere as for instance 210Pb was shown.

  2. Factors affecting the distribution of natural and anthropogenic radionuclides in the coastal Burullus Lake.

    PubMed

    El-Reefy, H I; Badran, H M; Sharshar, T; Hilal, M A; Elnimr, T

    2014-08-01

    In the present study, measurements of naturally occurring radioactive materials and (137)Cs activity in sediment were conducted for locations covering the entire Burullus Lake in order to gather information about radionuclides mobility and distribution. Low-background γ-spectrometry was employed to determine the activity concentrations of water and sediment samples. The activity concentrations of (226)Ra and (232)Th are close to uniform distribution in the lake environment. Among the different physical and chemical characteristics measured for water and sediment, only salinity and total organic matter content have the potential to affect the mobility of (137)Cs and (40)K. The results suggest that these two radionuclides are attached to different mobile particulates. Increasing salinity tends to strengthen the adsorption of (137)Cs and solubilization of (40)K in sediment. On the other hand, sediment with high organic matter content traps (137)Cs and (40)K associated particulates to bottom sediment. PMID:24657852

  3. Some geological characteristics in a regolith-limey shale rock profile through natural radionuclides distribution.

    PubMed

    Ferreira, Ademar de O; Bastos, Rodrigo O; Appoloni, Carlos R

    2010-09-01

    The objective of this work is to study some geological characteristics in a regolith-rock profile by analyzing the distribution of natural radionuclides along the profile by high resolution gamma ray spectrometry. The concentrations of radionuclides reflect some mineralogical characteristics of the rock matrix and also more recent events, such as weathering and erosion. The samples were collected in an abandoned limestone mine, in the city of Sapopema, Paraná State, Brazil. The stratigraphy is represented by an alternation of decimetric limestone layers, bituminous shale and some rhythmite layers. The ratios eTh/K obtained for all samples of the studied profile have equivalent values, indicating similar mineralogical characteristics of their detritic components. The ratio eTh/eU corroborates the fact that regolith samples belong to a much more oxidized environment, favoring the leaching of uranium. These results show that the measurement of radionuclide distribution in rocks and soils may be an important tool for the analysis of geological characteristics, such as mineralogy and oxidizing conditions. PMID:20304660

  4. Evaluation of occurrence and distribution of natural radionuclides in groundwater of Korea

    NASA Astrophysics Data System (ADS)

    Yun, S. W.; Lee, J. Y.; Park, Y. C.

    2015-12-01

    This study was conducted to evaluate the occurrence and distribution of natural radionuclides in groundwater of Korea. For this purpose, we collected the groundwater radionuclides data of 2000-2011 from National Institute of Environmental Research and available literatures. The sample data were classified into five groups according to the rock types and radionuclide levels were used to construct detailed concentration maps. Radon, uranium, gross-α and radium concentrations ranged from 0.4 to 64,688 pCi/L (mean: 4,907 pCi/L), 0 to 2,297 µg/L (mean: 27.5 µg/L), 0 to 312.0 (mean: 3.9 pCi/L) and 0 to 17.4 pCi/L (mean: 0.2 pCi/L), respectively. Radon concentrations in 562 (53.5%) of 1,501 wells exceeded 4,000 pCi/L, which is the maximum contaminant level by the US environmental protection agency. Uranium, gross-α, and radium concentrations in 121 (11.9%) of 1,031 wells, 34 (3.5%) of 978 wells and 4 (4.5%) of 89 wells exceeded 30 µg/L, 15 pCi/L and 5 pCi/L, respectively. Radionuclide mean concentration in igneous and metamorphic rocks showed higher levels than those of other rocks such as volcanic, carbonate and sedimentary rocks. However, we found that correlations among radionuclides were weak or not significant. This subject is supported by Korea Ministry of Environment as "the GAIA project".

  5. Distribution of naturally occurring radionuclides (U, Th) in Timahdit black shale (Morocco).

    PubMed

    Galindo, C; Mougin, L; Fakhi, S; Nourreddine, A; Lamghari, A; Hannache, H

    2007-01-01

    Attention has been focused recently on the use of Moroccan black oil shale as the raw material for production of a new type of adsorbent and its application to U and Th removal from contaminated wastewaters. The purpose of the present work is to provide a better understanding of the composition and structure of this shale and to determine its natural content in uranium and thorium. A black shale collected from Timahdit (Morocco) was analyzed by powder X-ray diffraction and SEM techniques. It was found that calcite, dolomite, quartz and clays constitute the main composition of the inorganic matrix. Pyrite crystals are also present. A selective leaching procedure, followed by radiochemical purification and alpha-counting, was performed to assess the distribution of naturally occurring radionuclides. Leaching results indicate that 238U, 235U, 234U, 232Th, 230Th and 228Th have multiple modes of occurrence in the shale. U is interpreted to have been concentrated under anaerobic conditions. An integrated isotopic approach showed the preferential mobilization of uranium carried by humic acids to carbonate and apatite phases. Th is partitioned between silicate minerals and pyrite. PMID:17098337

  6. Assessment of the vertical distribution of natural radionuclides in a mineralized uranium area in south-west Spain.

    PubMed

    Blanco Rodríguez, P; Vera Tomé, F; Lozano, J C

    2014-01-01

    Low-level alpha spectrometry techniques using semiconductor detectors (PIPS) and liquid scintillation (LKB Quantulus 1220™) were used to determine the activity concentration of (238)U, (234)U, (230)Th, (226)Ra, (232)Th, and (210)Pb in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were sampled from areas with different levels of influence from the installation and hence had different levels of contamination. The vertical profiles of the soils (down to 40 cm depth) were studied in order to evaluate the vertical distribution of the natural radionuclides. To determine the origin of these natural radionuclides the Enrichment Factor was used. Also, study of the activity ratios between radionuclides belonging to the same radioactive series allowed us to assess the different types of behaviors of the radionuclides involved. The vertical profiles for the radionuclide members of the (238)U series were different at each sampling point, depending on the level of influence of the installation. However, the profiles of each point were similar for the long-lived radionuclides of the (238)U series ((238)U, (234)U, (230)Th, and (226)Ra). Moreover, a major imbalance was observed between (210)Pb and (226)Ra in the surface layer, due to (222)Rn exhalation and the subsequent surface deposition of (210)Pb. PMID:24182407

  7. Distribution of natural radionuclides in soils and beach sands of Abana-Çatalzeytin (Kastamonu)

    NASA Astrophysics Data System (ADS)

    Kurnaz, Aslı; Özcan, Murat; ćetiner, M. Atıf

    2016-03-01

    A gamma spectrometric study of distribution of natural radionuclides in soil and beach sand samples collected from the terrestrial and coastal environment of Abana and Çatalzeytin counties of Kastamonu Province in Turkey was performed with the aim of estimating the radiation hazard of the tourist area and the concentrations of 238U, 232Th and 40K were determined. The activity concentrations of 238U, 232Th and 40K were determined in the ranges 14.95-56.0, 46.5-99.4 and 357.5-871.3 Bqkg-1 for soil samples and the mean concentrations were ascertained as 42.34, 71.24 and 624.18 Bqkg-1, respectively. In sand samples, 238U, 232Th and 40K contents were varied in the ranges of 13.35-41.6, 30.9-53.4 and 275.5-601.3 Bqkg-1 and the mean concentrations were ascertained as 20.57, 45.05 and 411.71 Bqkg-1, respectively. The mean annual effective doses were calculated as 113.08 and 69.16 µSvy-1 for the soil and sand samples, respectively.

  8. Distribution of natural radionuclides in the production and use of phosphate fertilizers in Brazil.

    PubMed

    Saueia, C H R; Mazzilli, B P

    2006-01-01

    The Brazilian phosphate fertilizer is obtained by wet reaction of igneous phosphate rock with concentrated sulphuric acid, giving as final product, phosphoric acid and dehydrated calcium sulphate (phosphogypsum) as by-products. Phosphoric acid is the starting material for triple superphosphate (TSP), single superphosphate (SSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP). The phosphate rock used as raw material presents in its composition radionuclides of the U and Th natural series. Taking this into account, the main aim of this paper is to evaluate the fluxes of natural radionuclides and radioactive disequilibria involved in the Brazilian industrial process of phosphoric acid production; to determine the content of radioactivity in several commercial fertilizers produced by this industry; to estimate their radiological impact in crop soils and the long term exposure due to their application. Radiological characterization of phosphate rock, phosphogypsum and phosphate fertilizers was performed by alpha and gamma spectrometry. The fertilizer samples, which are derived directly from phosphoric acid, MAP and DAP, presented in their composition low activity concentrations for 226Ra, 228Ra and 210Pb. As for U and Th, the concentrations found in MAP and DAP are more significant, up to 822 and 850Bqkg(-1), respectively. SSP and TSP, which are obtained by mixing phosphoric acid with different amounts of phosphate rock, presented higher concentrations of radionuclides, up to 1158Bqkg(-1) for (238)U, 1167Bqkg(-1) for (234)U, 1169Bqkg(-1) for 230Th, 879Bqkg(-1) for 226Ra, 1255Bqkg(-1) for 210Pb, 521Bqkg(-1) for 232Th, 246Bqkg(-1) for 228Ra and 302Bqkg(-1) for 228Th. Long term exposure due to successive fertilizer applications was evaluated. Internal doses due to the application of phosphate fertilizer for 10, 50 and 100 years were below 1mSvy(-1), showing that the radiological impact of such practice is negligible. PMID:16849030

  9. Assessment of spatial distribution and radiological hazardous nature of radionuclides in high background radiation area, Kerala, India.

    PubMed

    Ramasamy, V; Sundarrajan, M; Paramasivam, K; Meenakshisundaram, V; Suresh, G

    2013-03-01

    The concentration and distribution of the natural radionuclides ((238)U, (232)Th and (40)K) have been analyzed for the beach sediments of Kerala with an aim of evaluating the radiation hazards. The ranges of activity concentrations of (238)U, (232)Th and (40)K are BDL-1187 ± 21.7 Bq/kg, BDL-5328 ± 23.2 Bq/kg and BDL-693 ± 31.2 Bq/kg respectively. Radiological parameters such as absorbed dose rate, annual effective dose equivalent, annual gonadal dose equivalent, radium equivalent, hazard index, gamma Index, activity utilization index and excess lifetime cancer risk are calculated to know the complete radiological hazardous nature. Concentration of radionuclides ((238)U and (232)Th) and all the calculated radiological parameters are higher in site number S(23) (Chavara beach) due to the presence of rich deposits of black sands. Average concentrations of radionuclides ((238)U and (232)Th) and all calculated radiological parameters are higher than the recommended level. Both univariate and multivariate statistical analyses were applied effectively to assess the distribution of the radionuclides. Univariate statistical analysis shows that the confirmation of infrequent extreme deviations of all radioactive variables. Cluster analysis shows that light minerals play a role in cluster I sampling sites and heavy minerals may be played in sampling sites of other clusters. Calculated activity ratio confirmed the presence of light and heavy minerals in above mentioned sampling sites. The Kerala beach sediments pose significant radiological threat to the people living in the area and tourists going to the beaches for recreation or to the sailors and fishermen involved in their activities in the study area. PMID:23262126

  10. Distribution of natural and anthropogenic radionuclides in beach sand samples from Mediterranean Coast of Turkey

    NASA Astrophysics Data System (ADS)

    Özmen, S. F.; Cesur, A.; Boztosun, I.; Yavuz, M.

    2014-10-01

    Following Fukushima Dai-ichi Nuclear Power Plant accident, a huge amount of radionuclides were released in atmosphere and ocean. It's impact on the environment is of great concern to the good of the public at large. In this regard environmental radioactivity monitoring such as external dose rate and radioactivity measurements in environmental samples has been carried out. For this purpose, several beach sand samples were collected from south coast of the Turkey in September 2011 and radioactivity concentrations of 226Ra (238U), 228Ac (232Th), 40K, 134Cs and 137Cs were determined by gamma spectrometry using a high-purity Germanium detector. The measured activity concentrations in beach sand samples ranged from 4.0±0.5 to 21.5±1.8 Bq/kg, 1.8±0.4 to 27.9±2.4 Bq/kg, 19.0±2.2 to 590.3±28.6 Bq/kg and 0.1±0.0 to 1.0±0.1 Bq/kg for 226Ra, 232Th, 40K and 137Cs, respectively. However there was no sign of 134Cs in the sample spectrum after Fukushima Dai-ichi Nuclear Power Plant accident. Hence we can safely conclude that there was no significant material transfer from Fukushima to Turkey. The other activities are in good agreement with the published results of neighboring areas. The absorbed gamma dose rate (D) and the annual effective dose (AED) of beach sand samples were below the world wide average implying that the radiation hazard is insignificant. The data presented in this study would also be very useful to determine the possible future effects of the nuclear power plant to the environment.

  11. Activity size distributions of some naturally occurring radionuclides 7Be, 40K and 212Pb in indoor and outdoor environments.

    PubMed

    Mohamed, A

    2005-05-01

    The activity size distributions of natural radionuclides (7)Be and (40)K were measured outdoor in El-Minia city, Egypt by means of gamma spectroscopy. A low-pressure Berner cascade impactor was used as a sampling device. The activity size distribution of both (7)Be and (40)K was described by one log-normal distribution, which was represented by the accumulation mode. The activity median aerodynamic diameter (AMAD) of (7)Be and (40)K was determined to be 530 and 1550 nm with a relative geometric standard deviation (delta, which was defined as the dispersion of the peak) of 2.4 and 2, respectively. The same sampling device (Berner impactor) and a screen diffusion battery were used to measure the activity size distribution, activity concentration and unattached fraction (f(P)) of (212)Pb in indoor air of El-Minia City, Egypt. The mean activity median aerodynamic diameter (AMAD) of the accumulation mode for attached (212)Pb was determined to be 250 nm with a mean geometric standard deviation (delta) of 2.6. The mean value of the specific concentration of (212)Pb associated with that mode was determined to be 460+/-20 mBq m(-3). The activity median thermodynamic diameter (AMTD) of unattached (212)Pb was determined to be 1.25 nm with delta of 1.4. A mean unattached fraction (f(p)) of 0.13+/-0.02 was obtained at a mean aerosol particle concentration of 1.8 x 10(3) cm(-3). The mean activity concentration of unattached (212)Pb was found to be 19+/-3 mBq m(-3). It was found that the aerosol concentration played an important role in varying the unattached, attached activity concentration and unattached fraction (f(P)). PMID:15763482

  12. Distribution of Natural (U-238, Th-232, Ra-226) and Technogenic (Sr-90, Cs-137) Radionuclides in Soil-Plants Complex Near Issyk-Kul Lake, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Jovanovic, L.; Kaldybaev, B.; Djenbaev, B.; Tilenbaev, A.

    2012-04-01

    Researches on radionuclides distribution in the soil-plants complex provide essential information in understanding human exposure to natural and technogenic sources of radiation. It is necessary in establishing regulation relating to radiation protection. The aim of this study was the radiochemical analysis of the content natural radionuclides 238U, 232Th,226Ra and technogenic radionuclides content (90Sr, 137Cs) in soils near Issyk-Kul lake (Kyrgyzstan). Results of radiochemical analyses have shown, that the concentrations of thorium-232 are fluctuating in the limits (11.7-84.1)-10-4% in the soils. The greatest concentration of thorium-232 has been found in the light chestnut soils. The content of uranium-238 in the soils near Issyk-Kul lake is fluctuating from 2.8 up to 12.7-10-4%. Radium-226 has more migration ability in comparison with other heavy natural radionuclides. According to our research the concentrations of radium-226 are fluctuating in the limits (9.4-43.0)-10-11%. The greatest concentration of radium-226 (43,0±2,8)-10-11% has been determined in the light chestnut soil. In connection with global migration of contaminating substances, including radioactive, the special attention is given long-lived radionuclides strontium-90 and caesium-137 in food-chains, and agroecosystems. Results of radiochemical analyses have shown, that specific activity of strontium-90 is fluctuating in the range of 2.9 up to 11.1 Bq/kg, and caesium-137 from 3.7 up to 14,3 Bq/kg in the soil of agroecosystems in the region of Issyk-Kul. In soil samples down to 1 meter we have observed vertical migration of these radionuclides, they were found to accumulate on the surface of soil horizon (0-5 cm) and their specific activity sharply decreases with depth. In addition in high-mountain pastures characterized by horizontal migration of cattle in profiles of soil, it was discovered that specific activity of radionuclides are lower on the slope than at the foot of the mountain. The

  13. Natural radionuclide accumulation by raindrops

    NASA Astrophysics Data System (ADS)

    Gusev, Anatoly; Martin, Inacio; Shkevov, Rumen; Alves, Mauro

    2016-07-01

    The laboratory of environmental radiation of ITA (São José dos Campos, 23°11'11″S, 45°52'43″W, 650 MAMSL) performs simultaneous monitoring of a natural radiation background and meteorological parameters. A time resolution of up to 1 minute allows a detailed comparison of changes in meteorological parameters with those of a concentration of ambient radon progenies in the atmosphere. Results of a study of variation of a fallout of radon progenies ^{214}Pb and ^{214}Bi concomitanting rainfalls are present. The radionuclide fallout rate is reconstructed from the observed gamma rate through a simulation of the first kind Volterra integral equation with difference kernel, determined by ratio of precipitating rates of 214Pb and 214Bi and their decay half times. An original straightforward step-by-step procedure was used for the numerical solution of the equation. The radionuclide concentration in the rainwater is calculated as a ratio of the reconstructed fallout to the measured rainfall. It was observed that the radionuclide fallout rate increases as the rainfall one in approximately power 0.6, i.e. the same as the mean raindrop volume. The concentration thereafter decreases as the rainfall rate in power 0.4. A numerical simulation of the process of accumulation of the radionuclides during diffusion and coalescence drop growth and aerosol scavenging during a passage from a cloud to the ground was performed. The results of the simulations agree with the experimental data.

  14. Distribution and inventories of some artificial and naturally occurring radionuclides in medium to coarse-grained sediments of the channel

    NASA Astrophysics Data System (ADS)

    Boust, Dominique

    1999-12-01

    Concentrations of artificial ( 60Co, 137Cs, 238Pu and 239,240Pu) and naturally occurring radionuclides ( 40K, 212Pb and 214Pb, daughter nuclides of the 232Th and 238U series) in bottom sediments of the Channel are reported. They are grain-size modulated but usual grain-size normalisation methods fail due to the strong heterogeneity of the sediment admixture and/or the occurrence of rock debris in the area of concern. When plotted versus distance from Cap La Hague, 60Co and Pu isotope concentrations display a maximum in the Central Channel, but 137Cs do not. This is further explained by the contribution of the releases from the La Hague plant relative to other radionuclide inputs, especially Atlantic inflow and direct atmospheric fallout. Apparent transit times from Cap La Hague are derived from Pu isotopic ratios and yield average sediment velocities ranging from some kilometres to some tens of kilometres per year. Sediment inventories of artificial radionuclides show that a significant part of the input of 60Co and Pu isotopes is immobilised in the Channel seabed while most of the 137Cs input has been evacuated by water mass circulation.

  15. Illicit Trafficking of Natural Radionuclides

    NASA Astrophysics Data System (ADS)

    Friedrich, Steinhäusler; Lyudmila, Zaitseva

    2008-08-01

    Natural radionuclides have been subject to trafficking worldwide, involving natural uranium ore (U 238), processed uranium (yellow cake), low enriched uranium (<20% U 235) or highly enriched uranium (>20% U 235), radium (Ra 226), polonium (Po 210), and natural thorium ore (Th 232). An important prerequisite to successful illicit trafficking activities is access to a suitable logistical infrastructure enabling an undercover shipment of radioactive materials and, in case of trafficking natural uranium or thorium ore, capable of transporting large volumes of material. Covert en route diversion of an authorised uranium transport, together with covert diversion of uranium concentrate from an operating or closed uranium mines or mills, are subject of case studies. Such cases, involving Israel, Iran, Pakistan and Libya, have been analyzed in terms of international actors involved and methods deployed. Using international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (DSTO) and international experience gained from the fight against drug trafficking, a generic Trafficking Pathway Model (TPM) is developed for trafficking of natural radionuclides. The TPM covers the complete trafficking cycle, ranging from material diversion, covert material transport, material concealment, and all associated operational procedures. The model subdivides the trafficking cycle into five phases: (1) Material diversion by insider(s) or initiation by outsider(s); (2) Covert transport; (3) Material brokerage; (4) Material sale; (5) Material delivery. An Action Plan is recommended, addressing the strengthening of the national infrastructure for material protection and accounting, development of higher standards of good governance, and needs for improving the control system deployed by customs, border guards and security forces.

  16. Illicit Trafficking of Natural Radionuclides

    SciTech Connect

    Friedrich, Steinhaeusler; Lyudmila, Zaitseva

    2008-08-07

    Natural radionuclides have been subject to trafficking worldwide, involving natural uranium ore (U 238), processed uranium (yellow cake), low enriched uranium (<20% U 235) or highly enriched uranium (>20% U 235), radium (Ra 226), polonium (Po 210), and natural thorium ore (Th 232). An important prerequisite to successful illicit trafficking activities is access to a suitable logistical infrastructure enabling an undercover shipment of radioactive materials and, in case of trafficking natural uranium or thorium ore, capable of transporting large volumes of material. Covert en route diversion of an authorised uranium transport, together with covert diversion of uranium concentrate from an operating or closed uranium mines or mills, are subject of case studies. Such cases, involving Israel, Iran, Pakistan and Libya, have been analyzed in terms of international actors involved and methods deployed. Using international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (DSTO) and international experience gained from the fight against drug trafficking, a generic Trafficking Pathway Model (TPM) is developed for trafficking of natural radionuclides. The TPM covers the complete trafficking cycle, ranging from material diversion, covert material transport, material concealment, and all associated operational procedures. The model subdivides the trafficking cycle into five phases: (1) Material diversion by insider(s) or initiation by outsider(s); (2) Covert transport; (3) Material brokerage; (4) Material sale; (5) Material delivery. An Action Plan is recommended, addressing the strengthening of the national infrastructure for material protection and accounting, development of higher standards of good governance, and needs for improving the control system deployed by customs, border guards and security forces.

  17. Estimation of distribution coefficient of natural radionuclides in soil around uranium mines and its effect with ionic strength of water.

    PubMed

    Mishra, S; Maity, S; Pandit, G G

    2012-11-01

    The distribution coefficient, K(d) in soil is an important parameter to predict the migration of contaminants. In this study, uranium (U) and its decay products thorium (Th), radium (Ra), bismuth (Bi), lead (Pb) and polonium (Po), which may contaminate the soil and ground water around uranium mining areas, have been considered. Soil and ground water samples were collected from a proposed uranium mining site in India. The soil samples were characterised for different parameters affecting the K(d) values. The batch sorption method was employed to measure the K(d) of different radionuclides. The important factors affecting the batch method for K(d) estimation were identified and optimised. The variation of K(d) was observed with different ionic strength water samples. Results showed high K(d) values for Th(IV), Po(IV) and Pb(II) (log K(d) ∼4) and low K(d) (log K(d) ∼2-3) for U(VI), Ra(II) and Bi(III) in all three types of water with different ionic strength. PMID:22927651

  18. Distribution and environmental impacts of metals and natural radionuclides in marine sediments in-front of different wadies mouth along the Egyptian Red Sea Coast.

    PubMed

    el-Taher, A; Madkour, H A

    2011-02-01

    Forty-four marine sediment samples were collected in-front of wadis mouth along the Egyptian Red Sea coast: Wadi El-Hamra, Wadi El-Esh, Wadi Abu-Shaar, Wadi El-Gemal and Wadi Khashir (Hamata). Several investigations of natural activity and trace metals of surface sediments were carried out. Distributions of naturally occurring radioactive materials (NORM) of (226)Ra, (232)Th and (40)K in the marine sediments were determined using NaI (Tl) γ-ray spectrometry. The average activities (range) of natural radionuclides in all wadis in the studied areas are 27.38 (18-48) Bq kg(-1) for (226)Ra, 38.45 (34-110) Bq kg(-1) for (232)Th and 419.4 (214-641) Bq kg(-1) for (40)K. These results are in agreement with earlier reported data. A comparison of radionuclide activities in the sediment of the studied areas and in other coastal and aquatic environments is given. The radiation hazard parameters (absorbed dose rate, radium equivalent activity and external hazard index) are calculated and compared with the reported data. The results of measurements will serve as base line data and background reference level for Egyptian coastlines. PMID:21123076

  19. Spatial and vertical distribution and risk assessment of natural radionuclides in soils surrounding the lignite-fired power plants in Megalopolis basin, Greece.

    PubMed

    Papaefthymiou, H V; Manousakas, M; Fouskas, A; Siavalas, G

    2013-01-01

    Twenty soil profile samples and fourteen surface soil samples collected from the vicinity of the lignite-fired power plants in the Megalopolis basin (Greece) were analysed for their natural radionuclide concentration and (137)Cs, since fossil fuels are associated with naturally occurring radioactive materials and hence with radiological impact. No significant enhancement of surface soil radioactivity levels in the vicinity of lignite-fired plants was observed. A downcore decreasing trend of (137)Cs was observed in a number of cores reflecting its atmospheric origin, whereas the uniform distribution observed in a number of other cores gave information on the mechanical alteration of the soil. The average dose rate value was found to be 63 ± 22 nGy h(-1), while the annual average effective dose from the terrestrial gamma radiation was found to be 0.08 ± 0.03 mSv. PMID:23511709

  20. Natural radionuclides in ground waters and cores

    SciTech Connect

    Laul, J.C.; Smith, M.R.; Maiti, T.C.

    1988-01-01

    Investigations of natural radionuclides of uranium and thorium decay series in site-specific ground waters and cores (water/rock interaction) can provide information on the expected migration behavior of their radioactive waste and analog radionuclides in the unlikely event of radioactive releases from a repository. These data in ground waters can provide in situ retardation and sorption/desorption parameters for transport models and their associated kinetics (residence time). These data in cores can also provide information on migration or leaching up to a period of about one million years. Finally, the natural radionuclide data can provide baseline information for future monitoring of possible radioactive waste releases. The natural radionuclides of interest are {sup 238}U, {sup 234}Th, {sup 234}U, {sup 230}Th, {sup 226}Ra, {sup 222}Rn, {sup 210}Pb, {sup 210}Bi, {sup 210}Po, {sup 232}Th, {sup 228}Ra, {sup 228}Th, and {sup 224}Ra. The half-lives of the daughter radionuclides range from 3 days to 2.5 x 10{sup 5} yr. The data discussed are for low ionic strength ground waters from the Hanford (basalt) site and briny ground waters (high ionic strength) and cores from the Deaf Smith salt site. Similar applications of the natural radionuclide data can be extended to the Nevada Tuff repository site and subseabed disposal site. The concentrations of uranium, thorium, radium, lead, and polonium radionuclides are generally very low in ground waters. However, significant differences in disequilibrium exist between basalt and briny ground waters.

  1. Natural chelates for radionuclide decorporation

    DOEpatents

    Premuzic, E.T.

    1983-08-25

    This invention relates to the method and resulting chelates of desorbing a radionuclide selected from thorium, uranium, and plutonium containing cultures in a bioavailable form involving pseudomonas or other microorganisms. A preferred microorganism is Pseudomonas aeruginosa which forms multiple chelates with thorium in the range of molecular weight 1000 to 1000 and also forms chelates with uranium of molecular weight in the area of 100 to 1000 and 1000 to 2000.

  2. State of radionuclides in natural waters

    SciTech Connect

    Kulmatov, R.A.; Rakhmatov, U.; Kist, A.A.; Volkov, A.A.

    1987-03-01

    This work is devoted to a study of the kinetics of attainment of equilibrium between various forms of the radionuclide mercury-203 and to an evaluation of the part played by isotope exchange in this process. The radionuclide mercury-203 was added without a carrier to natural waters of the Syr-Dar'ya and Amu-Dar'ya Rivers and the Aral Sea in the cationic form (3). In order to determine the time of attainment of equilibrium between the forms of the radionuclide mercury-203 and the stable nuclide analogs, they used the methods of sorption on L-36 glass, AV-17 anion-exchanger, KU-2 cation-exchanger, extraction with chloroform plus isobutyl alcohol, and filtration.

  3. Distribution of radionuclides in Dardanelle Reservoir sediments.

    PubMed

    Forgy, J R; Epperson, C E; Swindle, D L

    1984-02-01

    Natural and reactor-discharged gamma-ray emitting radionuclides were measured in Dardanelle Reservoir surface sediments taken near the Arkansas Nuclear One Power Plant site. Samples represented several water depths and particle sizes, at 33 locations, in a field survey conducted in early September 1980. Radionuclide contents of dry sediments ranged as follows: natural radioactivity (40K as well as uranium and thorium decay products) 661-1210 Bq/kg; and reactor discharged radioactivity (137Cs, 134Cs, 60Co,, 58Co, 54Mn), no detectable activity to 237 Bq/kg. In general, radionuclide contents were positively correlated with decreasing sediment particle size. The average external whole-body and skin doses from all measurable reactor-discharged radionuclides were calculated according to the mathematical formula for determining external dose from sediment given by the U.S. Nuclear Regulatory Commission (NRC). Inside the discharge embayment near the reactor discharge canal, the doses were 1.7 X 10(-3) mSv/yr to the whole body and 2.0 X 10(-3) mSv/yr to the skin. Outside this area, the doses were 0.15 X 10(-3) and 0.18 X 10(-3) mSv/yr to the whole body and skin, respectively. PMID:6693264

  4. Distribution, enrichment and principal component analysis for possible sources of naturally occurring and anthropogenic radionuclides in the agricultural soil of Punjab state, India.

    PubMed

    Kumar, Ajay; Joshi, Vikram M; Mishra, Manish K; Karpe, Rupali; Rout, Sabyasachi; Narayanan, Usha; Tripathi, Raj M; Singh, Jaspal; Kumar, Sanjeev; Hegde, Ashok G; Kushwaha, Hari S

    2012-06-01

    Enrichment factor (EF) of elements including geo-accumulation indices for soil quality and principal component analysis (PCA) were used to identify the contributions of the origin of sources in the studied area. Results of (40)K, (137)Cs, (238)U and (232)Th including their decay series isotopes in the agricultural soil of Mansa and Bathinda districts in the state of Punjab were presented and discussed. The measured mean radioactivity concentrations for (238)U, (232)Th and (40)K in the agricultural soil of the studied area differed from nationwide average crustal abundances by 51, 17 and 43 %, respectively. The sequence of the EFs of radionuclides in soil from the greatest to the least was found to be (238)U > (40)K > (226)Ra > (137)Cs > (232)Th > (228)Ra. Even though the enrichment of naturally occurring radionuclides was found to be higher, they remained to be in I(geo) class of '0', indicating that the soil is uncontaminated with respect to these radionuclides. Among non-metals, N showed the highest EF and belonged to I(geo) class of '2', indicating that soil is moderately contaminated due to intrusion of fertiliser. The resulting data set of elemental contents in soil was also interpreted by PCA, which facilitates identification of the different groups of correlated elements. The levels of the (40)K, (238)U and (232)Th radionuclides showed a significant positive correlation with each other, suggesting a similar origin of their geochemical sources and identical behaviour during transport in the soil system. PMID:21893521

  5. Traces of natural radionuclides in animal food

    SciTech Connect

    Merli, Isabella Desan; Guazzelli da Silveira, Marcilei A.; Medina, Nilberto H.

    2014-11-11

    Naturally occurring radioactive materials are present everywhere, e.g., in soil, air, housing materials, food, etc. Therefore, human beings and animals receive internal exposure from radioactive elements inside their bodies through breathing and alimentation. Gamma radiation has enough energy to remove an electron from the atom and compromise the rearrangement of electrons in the search for a more stable configuration which can disturb molecule chemical bonding. Food ingestion is one of the most common forms of radioisotopes absorption. The goal of this work is the measurement of natural gamma radiation rates from natural radioisotopes present in animal food. To determine the concentration of natural radionuclides present in animal food gamma-ray spectrometry was applied. We have prepared animal food samples for poultry, fish, dogs, cats and cattle. The two highest total ingestion effective doses observed refers to a sample of mineral salt cattle, 95.3(15) μSv/year, rabbit chow, with a value of 48(5) μSv/year, and cattle mineral salt, with a value of 69(7) μSv/year, while the annual total dose value from terrestrial intake radionuclide is of the order of 290 μSv/year.

  6. Traces of natural radionuclides in animal food

    NASA Astrophysics Data System (ADS)

    Merli, Isabella Desan; da Silveira, Marcilei A. Guazzelli; Medina, Nilberto H.

    2014-11-01

    Naturally occurring radioactive materials are present everywhere, e.g., in soil, air, housing materials, food, etc. Therefore, human beings and animals receive internal exposure from radioactive elements inside their bodies through breathing and alimentation. Gamma radiation has enough energy to remove an electron from the atom and compromise the rearrangement of electrons in the search for a more stable configuration which can disturb molecule chemical bonding. Food ingestion is one of the most common forms of radioisotopes absorption. The goal of this work is the measurement of natural gamma radiation rates from natural radioisotopes present in animal food. To determine the concentration of natural radionuclides present in animal food gamma-ray spectrometry was applied. We have prepared animal food samples for poultry, fish, dogs, cats and cattle. The two highest total ingestion effective doses observed refers to a sample of mineral salt cattle, 95.3(15) μSv/year, rabbit chow, with a value of 48(5) μSv/year, and cattle mineral salt, with a value of 69(7) μSv/year, while the annual total dose value from terrestrial intake radionuclide is of the order of 290 μSv/year.

  7. Reuse of Material Containing Natural Radionuclides - 12444

    SciTech Connect

    Metlyaev, E.G.; Novikova, N.J.

    2012-07-01

    Disposal of and use of wastes containing natural radioactive material (NORM) or technologically enhanced natural radioactive material (TENORM) with excessive natural background as a building material is very important in the supervision body activity. At the present time, the residents of Octyabrsky village are under resettlement. This village is located just near the Priargunsky mining and chemical combine (Ltd. 'PPGHO'), one of the oldest uranium mines in our country. The vacated wooden houses in the village are demolished and partly used as a building material. To address the issue of potential radiation hazard of the wooden beams originating from demolition of houses in Octyabrsky village, the contents of the natural radionuclides (K-40, Th-232, Ra-226, U- 238) are being determined in samples of the wooden beams of houses. The NORM contents in the wooden house samples are higher, on average, than their content in the reference sample of the fresh wood shavings, but the range of values is rather large. According to the classification of waste containing the natural radionuclides, its evaluation is based on the effective specific activity. At the effective specific activity lower 1.5 kBq/kg and gamma dose rate lower 70 μR/h, the material is not considered as waste and can be used in building by 1 - 3 classes depending upon A{sub eff} value. At 1.5 kBq/kg < A{sub eff} ≤ 4 kBq/kg (4 class), the wooden beams might be used for the purpose of the industrial building, if sum of ratios between the radionuclide specific activity and its specific activity of minimum significance is lower than unit. The material classified as the waste containing the natural radionuclides has A{sub eff} higher 1.5 kBq /kg, and its usage for the purpose of house-building and road construction is forbidden. As for the ash classification and its future usage, such usage is unreasonable, because, according to the provided material, more than 50% of ash samples are considered as radioactive

  8. Natural radionuclide analysis in chattarpur area of southeastern coastal area of Odisha, India

    NASA Astrophysics Data System (ADS)

    Rautela, Bhagwat; Gusain, Gurupad; Yadav, Manjulata; Sahoo, Sarat; Tokonami, Shinji; Ramola, Rakesh

    2013-08-01

    The energy released in a spontaneous decay process of natural radionuclides is the main source of the total radiation dose to human beings. Natural radionuclides are widely distributed in soil, rocks, air, and groundwater. In present investigation, the analysis of terrestrial radionuclides such as 226Ra, 232Th, and 40K in soil and sand of Chattarpur area of southeastern coast of Odisha has been carried out using NaI(Tl) gamma ray detector. The higher activity concentrations of naturally occurring radionuclides have been reported from the study area. The gamma radiationdose originating from the terrestrial radionuclides was found to vary from 95 to 1813 nGy/h with an average of 700 nGy/h. This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details.

  9. Natural Radionuclide Activity Concentrations In Spas Of Argentina

    SciTech Connect

    Gnoni, G.; Czerniczyniec, M.; Canoba, A.; Palacios, M.

    2008-08-07

    Geothermal waters have been used on a large scale for bathing, drinking and medical purposes. These waters can contain natural radionuclides that may increase the exposure to people. In this work the most important natural radionuclide activity concentrations in different thermal spas of Argentina were measured to characterize waters and to evaluate the exposure of workers and members of the public.

  10. Monitored Natural Attenuation For Radionuclides In Ground Water - Technical Issues

    EPA Science Inventory

    Remediation of ground water contaminated with radionuclides may be achieved using attenuation-based technologies. These technologies may rely on engineered processes (e.g., bioremediation) or natural processes (e.g., monitored natural attentuation) within the subsurface. In gen...

  11. Nevada test site radionuclide inventory and distribution: project operations plan

    SciTech Connect

    Kordas, J.F.; Anspaugh, L.R.

    1982-06-01

    This document is the operational plan for conducting the Radionuclide Inventory and Distribution Program (RIDP) at the Nevada Test Site (NTS). The basic objective of this program is to inventory the significant radionuclides of NTS origin in NTS surface soil. The expected duration of the program is five years. This plan includes the program objectives, methods, organization, and schedules.

  12. The geochemical behavior of natural radionuclides in coastal waters: A modeling study for the Huelva estuary

    NASA Astrophysics Data System (ADS)

    Periáñez, Raúl; Hierro, Almudena; Bolívar, Juan Pedro; Vaca, Federico

    2013-10-01

    A numerical model to study the behavior and distribution of natural radionuclides in sediments of an estuary (Odiel and Tinto rivers, SW Spain) affected by acid mine drainage and industrial activities has been developed. The model solves water circulation due to tides and river stream flows. The dispersion model includes uptake/release reactions of radionuclides between the dissolved phase and bed sediments in a dynamic way, using kinetic transfer coefficients. Seasonal pH and chlorinity distributions are simulated, and a formulation has been developed to consider these seasonal variations on kinetic coefficients. Calculated concentrations of 226Ra and 238U in sediments have been compared with measurements from four seasonal sampling campaigns. Numerical experiments have been carried out to study the relative significance of the different radionuclides sources into the estuary as well as the effect of the two components of water circulation (tides are river flows) on radionuclide dispersion patterns.

  13. Method for image reconstruction of moving radionuclide source distribution

    DOEpatents

    Stolin, Alexander V.; McKisson, John E.; Lee, Seung Joon; Smith, Mark Frederick

    2012-12-18

    A method for image reconstruction of moving radionuclide distributions. Its particular embodiment is for single photon emission computed tomography (SPECT) imaging of awake animals, though its techniques are general enough to be applied to other moving radionuclide distributions as well. The invention eliminates motion and blurring artifacts for image reconstructions of moving source distributions. This opens new avenues in the area of small animal brain imaging with radiotracers, which can now be performed without the perturbing influences of anesthesia or physical restraint on the biological system.

  14. Natural chelating agents for radionuclide decorporation

    DOEpatents

    Premuzic, E.T.

    1985-06-11

    This invention relates to the production of metal-binding compounds useful for the therapy of heavy metal poisoning, for biological mining and for decorporation of radionuclides. The present invention deals with an orderly and effective method of producing new therapeutically effective chelating agents. This method uses challenge biosynthesis for the production of chelating agents that are specific for a particular metal. In this approach, the desired chelating agents are prepared from microorganisms challenged by the metal that the chelating agent is designed to detoxify. This challenge induces the formation of specific or highly selective chelating agents. The present invention involves the use of the challenge biosynthetic method to produce new complexing/chelating agents that are therapeutically useful to detoxify uranium, plutonium, thorium and other toxic metals. The Pseudomonas aeruginosa family of organisms is the referred family of microorganisms to be used in the present invention to produce the new chelating agent because this family is known to elaborate strains resistant to toxic metals.

  15. Behaviour and fluxes of natural radionuclides in the production process of a phosphoric acid plant.

    PubMed

    Bolívar, J P; Martín, J E; García-Tenorio, R; Pérez-Moreno, J P; Mas, J L

    2009-02-01

    In recent years there has been an increasing awareness of the occupational and public hazards of the radiological impact of non-nuclear industries which process materials containing naturally occurring radionuclides. These include the industries devoted to the production of phosphoric acid by treating sedimentary phosphate rocks enriched in radionuclides from the uranium series. With the aim of evaluating the radiological impact of a phosphoric acid factory located in the south-western Spain, the distribution and levels of radionuclides in the materials involved in its production process have been analysed. In this way, it is possible to asses the flows of radionuclides at each step and to locate those points where a possible radionuclide accumulation could be produced. A set of samples collected along the whole production process were analysed to determine their radionuclide content by both alpha-particle and gamma spectrometry techniques. The radionuclide fractionation steps and enrichment sources have been located, allowing the establishment of their mass (activity) balances per year. PMID:19064324

  16. The enrichment behavior of natural radionuclides in pulverized oil shale-fired power plants.

    PubMed

    Vaasma, Taavi; Kiisk, Madis; Meriste, Tõnis; Tkaczyk, Alan Henry

    2014-12-01

    The oil shale industry is the largest producer of NORM (Naturally Occurring Radioactive Material) waste in Estonia. Approximately 11-12 million tons of oil shale containing various amounts of natural radionuclides is burned annually in the Narva oil shale-fired power plants, which accounts for approximately 90% of Estonian electricity production. The radionuclide behavior characteristics change during the fuel combustion process, which redistributes the radionuclides between different ash fractions. Out of 24 operational boilers in the power plants, four use circulating fluidized bed (CFB) technology and twenty use pulverized fuel (PF) technology. Over the past decade, the PF boilers have been renovated, with the main objective to increase the efficiency of the filter systems. Between 2009 and 2012, electrostatic precipitators (ESP) in four PF energy blocks were replaced with novel integrated desulphurization technology (NID) for the efficient removal of fly ash and SO2 from flue gases. Using gamma spectrometry, activity concentrations and enrichment factors for the (238)U ((238)U, (226)Ra, (210)Pb) and (232)Th ((232)Th, (228)Ra) family radionuclides as well as (40)K were measured and analyzed in different PF boiler ash fractions. The radionuclide activity concentrations in the ash samples increased from the furnace toward the back end of the flue gas duct. The highest values in different PF boiler ash fractions were in the last field of the ESP and in the NID ash, where radionuclide enrichment factors were up to 4.2 and 3.3, respectively. The acquired and analyzed data on radionuclide activity concentrations in different PF boiler ashes (operating with an ESP and a NID system) compared to CFB boiler ashes provides an indication that changes in the fuel (oil shale) composition and boiler working parameters, as well as technological enhancements in Estonian oil shale fired power plants, have had a combined effect on the distribution patterns of natural radionuclides

  17. Analytical evaluation of natural radionuclides and their radioactive equilibrium in raw materials and by-products.

    PubMed

    Ji, Young-Yong; Chung, Kun Ho; Lim, Jong-Myoung; Kim, Chang-Jong; Jang, Mee; Kang, Mun Ja; Park, Sang Tae

    2015-03-01

    An investigation into the distribution of natural radionuclides and radioactive secular equilibrium in raw materials and by-products in a domestic distribution was conducted to deduce the optimum conditions for the analytical evaluation of natural radionuclides for (238)U, (226)Ra, and (232)Th using a gamma-ray spectrometer and inductively coupled plasma mass spectrometer (ICP-MS). The range of the specific activities of natural radionuclides was first evaluated by analyzing (228)Ac and (214)Bi, which are (232)Th and (226)Ra indicators, respectively, in about 100 samples of raw materials and by-products through a gamma-ray spectrometer. From further experiments using several samples selected based on the results of the distribution of natural radionuclides, the validation of their analytical evaluations for the indirect measurements using a gamma-ray spectrometer and direct measurements using ICP-MS was assured by comparing their results. Chemically processed products from the raw materials, such as Zr sand and ceramic balls, were generally shown for the type of bead and particularly analyzed showing a definite disequilibrium with above a 50% difference between (238)U and (226)Ra in the uranium series and (232)Th and (228)Ra in the thorium series. PMID:25527894

  18. Distribution of artificial radionuclides in lacustrine sediments in China.

    PubMed

    Wu, Fengchang; Zheng, Jian; Liao, Haiqing; Yamada, Masatoshi

    2011-07-01

    Establishing accurate historical records of the distribution, inventory and source of artificial radionuclides in the environment is important for environmental monitoring and radiological health protection due to their potential toxicity, and is also useful for identification and risk assessment of possible future environmental inputs of radionuclides from nuclear weapons tests and accidental release from the nuclear fuel reprocessing facilities or nuclear power reactors. A sector-field inductively coupled plasma mass spectrometer was used to study the recent sedimentation of Pu isotopes in 11 lakes in China. The distribution of (137)Cs was investigated using the conventional radiometric analytical methods. Based on the isotopic compositions of Pu and the activity ratio of (137)Cs/(239+240)Pu, the sources of artificial radionuclides were identified. The potential applications of Pu isotopes for sediment dating and for regional and global environmental change studies were discussed. PMID:21498412

  19. Natural and man-made radionuclides in sediments of an inlet in Rio de Janeiro State, Brazil.

    PubMed

    Carvalho, Franciane Martins de; Lauria, Dejanira da Costa; Ribeiro, Fernando Carlos Araújo; Fonseca, Rafael Tonelli; Peres, Sueli da Silva; Martins, Nádia Soido Falcão

    2016-06-15

    The distribution of natural radionuclides (226)Ra, (228)Ra, (40)K and man-made radionuclides ((54)Mn, (60)Co and (137) Cs) in the surface sediments of an inlet of Ribeira Bay were investigated. Sediment samples were collected and analyzed for radionuclides, organic matter, carbonate, sulfate, cationic exchange capacity and grain size composition. The natural radionuclide concentrations ranged from 4.4 to 45, from 10 to 93, from 66 to 1347Bq·kg(-1) dry weight for (226)Ra, (228)Ra and (40)K, respectively. Natural radionuclide concentrations tend to be higher in the silt fraction, which determines their pattern distributions. Only one sample presented measurable concentration for (137)Cs, while (54)Mn was detected in two samples and (60)Co in four sediment samples. Man-made radionuclides present a maximum value of dose external four times lower than the normal background and the potential risk due to the presence of man-made radionuclides in sediments is lower than the risk provided by the natural radionuclides. PMID:27084201

  20. Natural chelating agents for radionuclide decorporation

    DOEpatents

    Premuzic, Eugene T.

    1988-01-01

    This invention relates to the preparation of new, naturally produced chelating agents as well as to the method and resulting chelates of desorbing cultures in a bioavailable form involving Pseudomonas species or other microorganisms. A preferred microorganism is Pseudomonas aeruginosa which forms multiple chelates with thorium in the range of molecular weight 100-1,000 and also forms chelates with uranium of molecular weight in the area of 100-1,000 and 1,000-2,000.

  1. Empirical distributions of radionuclides, from RWMIS data

    SciTech Connect

    Atwood, C.L.; Schlafman, M.J.

    1993-04-01

    The RWMIS data base gives data on each shipment of waste received at the Transuranic Storage Area, including the total volume of the shipment and the activity (Ci) of each nuclide in the shipment. This report assumes that the RWMIS numbers are correct, and considers the waste containers now retrievably stored at the Transuranic Storage Area. The total decay-corrected activities are summarized for several classes, such as for transuranic (TRU) waste and non-TRU waste, for {alpha}-emitters and {beta}/{gamma}-emitters, by waste originator and by current storage location. The total activity for each nuclide is also given. The empirical distributions are then given for a number of classes and individual nuclides, reflecting the variability between waste shipments. They are expressed in terms of mCi/cu-ft; for fissionable nuclides, the same information is also expressed in terms of mg/cu-ft; finally, the distribution is also given for the committed effective dose equivalent from inhalation, expressed in Mrem/cu-ft. The empirical distributions can be used for simulating the contents of a random waste container with a postulated volume. Examples are given illustrating the uses and limitations of the results.

  2. Radionuclide distributions and sorption behavior in the Susquehanna--Chesapeake Bay System

    SciTech Connect

    Olsen, C.R.; Larsen, I.L.; Lowry, P.D.; McLean, R.I.; Domotor, S.L.

    1989-01-01

    Radionuclides released into the Susquehanna--Chesapeake System from the Three Mile Island, Peach Bottom, and Calvert Cliffs nuclear power plants are partitioned among dissolved, particulate, and biological phases and may thus exist in a number of physical and chemical forms. In this project, we have measured the dissolved and particulate distributions of fallout /sup 137/Cs; reactor-released /sup 137/Cs, /sup 134/Cs, /sup 65/Zn, /sup 60/Co, and /sup 58/Co; and naturally occurring /sup 7/Be and /sup 210/Pb in the lower Susquehanna River and Upper Chesapeake Bay. In addition, we chemically leached suspended particles and bottom sediments in the laboratory to determine radionuclide partitioning among different particulate-sorbing phases to complement the site-specific field data. This information has been used to document the important geochemical processes that affect the transport, sorption, distribution, and fate of reactor-released radionuclides (and by analogy, other trace contaminants) in this river-estuarine system. Knowledge of the mechanisms, kinetic factors, and processes that affect radionuclide distributions is crucial for predicting their biological availability, toxicity, chemical behavior, physical transport, and accumulation in aquatic systems. The results from this project provide the information necessary for developing accurate radionuclide-transport and biological-uptake models. 76 refs., 12 figs.

  3. Review of Distribution Coefficients for Radionuclides in Carbonate Minerals

    SciTech Connect

    Sutton, M

    2009-08-14

    An understanding of the transport of radionuclides in carbonate minerals is necessary to be able to predict the fate of (and potentially remediate) radionuclides in the environment. In some environments, carbonate minerals such as calciate, aragonite, dolomite and limestone are present and an understanding of the sorption of radionuclides in these carbonate minerals is therefore advantageous. A list of the radionuclides of interest is given in Table 1. The distribution coefficient, K{sub d} is defined as the ratio of the contaminant concentration bound on the solid phase to the contaminant concentration remaining in the liquid phase at equilibrium. Some authors report distribution coefficients and other report partition coefficients, the data presented in this work assumes equality between these two terms, and data are presented and summarized in this work as logarithmic distribution coefficient (log K{sub D}). Published literature was searched using two methods. Firstly, the JNC Sorption Database, namely Shubutani et al (1999), and Suyama and Sasamoto (2004) was used to select elements of interest and a number of carbonate minerals. Secondly, on-line literature search tools were used to locate relevant published articles from 1900 to 2009. Over 300 data points covering 16 elements (hydrogen, carbon, calcium, nickel, strontium, technetium, palladium, iodine, cesium, samarium, europium, holmium, uranium, neptunium, plutonium and americium) were used to calculate an average and range of log K{sub d} values for each element. Unfortunately, no data could be found for chlorine, argon, krypton, zirconium, niobium, tin, thorium and curium. A description of the data is given below, together with the average, standard deviation, minimum, maximum and number of inputs for radionuclide K{sub d} values for calcite, aragonate, limestone, dolomite and unidentified carbonate rocks in Table 2. Finally, the data are condensed into one group (carbonate minerals) of data for each

  4. Radionuclide Inventory Distribution Project Data Evaluation and Verification White Paper

    SciTech Connect

    NSTec Environmental Restoration

    2010-05-17

    Testing of nuclear explosives caused widespread contamination of surface soils on the Nevada Test Site (NTS). Atmospheric tests produced the majority of this contamination. The Radionuclide Inventory and Distribution Program (RIDP) was developed to determine distribution and total inventory of radionuclides in surface soils at the NTS to evaluate areas that may present long-term health hazards. The RIDP achieved this objective with aerial radiological surveys, soil sample results, and in situ gamma spectroscopy. This white paper presents the justification to support the use of RIDP data as a guide for future evaluation and to support closure of Soils Sub-Project sites under the purview of the Federal Facility Agreement and Consent Order. Use of the RIDP data as part of the Data Quality Objective process is expected to provide considerable cost savings and accelerate site closures. The following steps were completed: - Summarize the RIDP data set and evaluate the quality of the data. - Determine the current uses of the RIDP data and cautions associated with its use. - Provide recommendations for enhancing data use through field verification or other methods. The data quality is sufficient to utilize RIDP data during the planning process for site investigation and closure. Project planning activities may include estimating 25-millirem per industrial access year dose rate boundaries, optimizing characterization efforts, projecting final end states, and planning remedial actions. In addition, RIDP data may be used to identify specific radionuclide distributions, and augment other non-radionuclide dose rate data. Finally, the RIDP data can be used to estimate internal and external dose rates. The data quality is sufficient to utilize RIDP data during the planning process for site investigation and closure. Project planning activities may include estimating 25-millirem per industrial access year dose rate boundaries, optimizing characterization efforts, projecting final

  5. Distribution of radionuclides during melting of carbon steel

    SciTech Connect

    Thurber, W.C.; MacKinney, J.

    1997-02-01

    During the melting of steel with radioactive contamination, radionuclides may be distributed among the metal product, the home scrap, the slag, the furnace lining and the off-gas collection system. In addition, some radionuclides will pass through the furnace system and vent to the atmosphere. To estimate radiological impacts of recycling radioactive scrap steel, it is essential to understand how radionuclides are distributed within the furnace system. For example, an isotope of a gaseous element (e.g., radon) will exhaust directly from the furnace system into the atmosphere while a relatively non-volatile element (e.g., manganese) can be distributed among all the other possible media. This distribution of radioactive contaminants is a complex process that can be influenced by numerous chemical and physical factors, including composition of the steel bath, chemistry of the slag, vapor pressure of the particular element of interest, solubility of the element in molten iron, density of the oxide(s), steel melting temperature and melting practice (e.g., furnace type and size, melting time, method of carbon adjustment and method of alloy additions). This paper discusses the distribution of various elements with particular reference to electric arc furnace steelmaking. The first two sections consider the calculation of partition ratios for elements between metal and slag based on thermodynamic considerations. The third section presents laboratory and production measurements of the distribution of various elements among slag, metal, and the off-gas collection system; and the final section provides recommendations for the assumed distribution of each element of interest.

  6. Naturally-occurring chemical analogues for repository-derived radionuclides

    SciTech Connect

    Miller, B.

    1996-12-01

    Studies of natural systems are a valuable means of gaining information on the behavior of elements and radionuclides in the geosphere or biosphere that may be used to support performance assessments for radioactive waste repositories. However, these natural system studies face the problem that some of the chemical and isotopic species that occur in radioactive wastes do not occur naturally. Therefore, when attempting to study transport processes for these species other, naturally-occurring species must be examined as {open_quote}chemical analogues{close_quote} for the waste species. Chemical analogues are chosen on the basis of some similarity with the chemical behavior of the waste species in relevant physico-chemical environments. This is a tricky procedure and each system must be considered on a case-by-case basis, although some guidelines can be established and these are given here.

  7. Carotenoid Distribution in Nature.

    PubMed

    Alcaíno, Jennifer; Baeza, Marcelo; Cifuentes, Víctor

    2016-01-01

    Carotenoids are naturally occurring red, orange and yellow pigments that are synthesized by plants and some microorganisms and fulfill many important physiological functions. This chapter describes the distribution of carotenoid in microorganisms, including bacteria, archaea, microalgae, filamentous fungi and yeasts. We will also focus on their functional aspects and applications, such as their nutritional value, their benefits for human and animal health and their potential protection against free radicals. The central metabolic pathway leading to the synthesis of carotenoids is described as the three following principal steps: (i) the synthesis of isopentenyl pyrophosphate and the formation of dimethylallyl pyrophosphate, (ii) the synthesis of geranylgeranyl pyrophosphate and (iii) the synthesis of carotenoids per se, highlighting the differences that have been found in several carotenogenic organisms and providing an evolutionary perspective. Finally, as an example, the synthesis of the xanthophyll astaxanthin is discussed. PMID:27485217

  8. Natural radionuclide concentrations in two phosphate ores of east Algeria.

    PubMed

    Lakehal, Ch; Ramdhane, M; Boucenna, A

    2010-05-01

    Ore is considered as an important source of many elements such as the iron, phosphorus, and uranium. Concerning the natural radionuclides, their concentrations vary from an ore to other depending on the chemical composition of each site. In this work, two phosphate ores found in East of Algeria have been chosen to assess the activity concentration of natural radionuclides represented mainly by three natural radioactive series (238)U, (235)U and (232)Th, and the primordial radionuclide (40)K where they were determined using ultra-low background, high-resolution gamma-ray spectroscopy. The measured activity concentrations of radioactive series ranged from 6.2 +/- 0.4 to 733 +/- 33 Bq.kg(-1) for the (232)Th series, from 249 +/- 16 to 547 +/- 39 Bq.kg(-1) for the (238)U series, around 24.2 +/- 2.5 Bq.kg(-1) for the (235)U series, and from 1.4 +/- 0.2 to 6.7 +/- 0.7 Bq.kg(-1) for (40)K. To assess exposure to gamma radiation in the two ores, from specific activities of (232)Th, (40)K and (226)Ra, three indexes were determined: Radium equivalent (Ra(eq)), external and internal hazard indexes (H(ex) and H(in)), their values ranged from 831 +/- 8 to 1298 +/- 14 Bq.kg(-1) for Ra(eq), from 2.2 +/- 0.4 to 3.5 +/- 0.7 Bq.kg(-1) for H(ex), and from 4.2 +/- 0.7 to 4.5 +/- 0.7 Bq.kg(-1) for H(in). PMID:20303630

  9. Environmental radionuclide distribution in Georgia after the Chernobyl accident

    SciTech Connect

    Mosulishvili, L.M.; Shoniya, N.I.; Katamadze, N.M.

    1994-01-01

    Atmospheric Chernobyl-released radioactivity, assessed at about 2 x 10{sup 18} Bq, caused global environmental contamination. Contaminated air masses appeared in the Transcaucasian region in early May, 1986. Rains that month promoted intense radionuclide deposition all over Georgia. The contamination level of western Georgia considerably exceeded the contamination level of eastern Georgia. The Black Sea coast of Georgia suffered from the Chernobyl accident as much as did strongly contaminated areas of the Ukraine and Belarus`. Unfortunately, governmental decrees on countermeasures against the consequences of the Chernobyl accident at that time did not even refer to the coast of Georgia. The authors observed the first increase in radioactivity background in rainfall samples collected on May 2, 1986, in Tbilisi. {gamma}-Spectrometric measurements of aerosol filters, vegetation, food stuffs, and other objects, in addition to rainfall, persistently confirmed the occurrence of short-lived radionuclides, including {sup 131}I. At first, this fact seemed unbelievable, because the Chernobyl accident had occurred only 4-5 days earlier and far from Georgia. However, these arguments proved to be faulty. Soon, environmental monitoring of radiation in Georgia became urgent. Environmental radionuclide distribution in Georgia shortly after the Chernobyl accident, as well as the methods of analysis, are reported in this paper.

  10. A comparison of the dose from natural radionuclides and artificial radionuclides after the Fukushima nuclear accident

    PubMed Central

    Hosoda, Masahiro; Tokonami, Shinji; Omori, Yasutaka; Ishikawa, Tetsuo; Iwaoka, Kazuki

    2016-01-01

    Due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the evacuees from Namie Town still cannot reside in the town, and some continue to live in temporary housing units. In this study, the radon activity concentrations were measured at temporary housing facilities, apartments and detached houses in Fukushima Prefecture in order to estimate the annual internal exposure dose of residents. A passive radon–thoron monitor (using a CR-39) and a pulse-type ionization chamber were used to evaluate the radon activity concentration. The average radon activity concentrations at temporary housing units, including a medical clinic, apartments and detached houses, were 5, 7 and 9 Bq m−3, respectively. Assuming the residents lived in these facilities for one year, the average annual effective doses due to indoor radon in each housing type were evaluated as 0.18, 0.22 and 0.29 mSv, respectively. The average effective doses to all residents in Fukushima Prefecture due to natural and artificial sources were estimated using the results of the indoor radon measurements and published data. The average effective dose due to natural sources for the evacuees from Namie Town was estimated to be 1.9 mSv. In comparison, for the first year after the FDNPP accident, the average effective dose for the evacuees due to artificial sources from the accident was 5.0 mSv. Although residents' internal and external exposures due to natural radionuclides cannot be avoided, it might be possible to lower external exposure due to the artificial radionuclides by changing some behaviors of residents. PMID:26838130

  11. A comparison of the dose from natural radionuclides and artificial radionuclides after the Fukushima nuclear accident.

    PubMed

    Hosoda, Masahiro; Tokonami, Shinji; Omori, Yasutaka; Ishikawa, Tetsuo; Iwaoka, Kazuki

    2016-07-01

    Due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the evacuees from Namie Town still cannot reside in the town, and some continue to live in temporary housing units. In this study, the radon activity concentrations were measured at temporary housing facilities, apartments and detached houses in Fukushima Prefecture in order to estimate the annual internal exposure dose of residents. A passive radon-thoron monitor (using a CR-39) and a pulse-type ionization chamber were used to evaluate the radon activity concentration. The average radon activity concentrations at temporary housing units, including a medical clinic, apartments and detached houses, were 5, 7 and 9 Bq m(-3), respectively. Assuming the residents lived in these facilities for one year, the average annual effective doses due to indoor radon in each housing type were evaluated as 0.18, 0.22 and 0.29 mSv, respectively. The average effective doses to all residents in Fukushima Prefecture due to natural and artificial sources were estimated using the results of the indoor radon measurements and published data. The average effective dose due to natural sources for the evacuees from Namie Town was estimated to be 1.9 mSv. In comparison, for the first year after the FDNPP accident, the average effective dose for the evacuees due to artificial sources from the accident was 5.0 mSv. Although residents' internal and external exposures due to natural radionuclides cannot be avoided, it might be possible to lower external exposure due to the artificial radionuclides by changing some behaviors of residents. PMID:26838130

  12. Risk Due to Radiological Terror Attacks With Natural Radionuclides

    NASA Astrophysics Data System (ADS)

    Friedrich, Steinhäusler; Stan, Rydell; Lyudmila, Zaitseva

    2008-08-01

    The naturally occurring radionuclides radium (Ra-226) and polonium (Po-210) have the potential to be used for criminal acts. Analysis of international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (CSTO), operated at the University of Salzburg, shows that several acts of murder and terrorism with natural radionuclides have already been carried out in Europe and Russia. Five different modes of attack (T) are possible: (1) Covert irradiation of an individual in order to deliver a high individual dose; (2) Covert irradiation of a group of persons delivering a large collective dose; (3) Contamination of food or drink; (4) Generation of radioactive aerosols or solutions; (5) Combination of Ra-226 with conventional explosives (Dirty Bomb). This paper assesses the risk (R) of such criminal acts in terms of: (a) Probability of terrorist motivation deploying a certain attack mode T; (b) Probability of success by the terrorists for the selected attack mode T; (c) Primary damage consequence (C) to the attacked target (activity, dose); (d) Secondary damage consequence (C') to the attacked target (psychological and socio-economic effects); (e) Probability that the consequences (C, C') cannot be brought under control, resulting in a failure to manage successfully the emergency situation due to logistical and/or technical deficits in implementing adequate countermeasures. Extensive computer modelling is used to determine the potential impact of such a criminal attack on directly affected victims and on the environment.

  13. Risk Due to Radiological Terror Attacks With Natural Radionuclides

    SciTech Connect

    Friedrich, Steinhaeusler; Lyudmila, Zaitseva; Stan, Rydell

    2008-08-07

    The naturally occurring radionuclides radium (Ra-226) and polonium (Po-210) have the potential to be used for criminal acts. Analysis of international incident data contained in the Database on Nuclear Smuggling, Theft and Orphan Radiation Sources (CSTO), operated at the University of Salzburg, shows that several acts of murder and terrorism with natural radionuclides have already been carried out in Europe and Russia. Five different modes of attack (T) are possible: (1) Covert irradiation of an individual in order to deliver a high individual dose; (2) Covert irradiation of a group of persons delivering a large collective dose; (3) Contamination of food or drink; (4) Generation of radioactive aerosols or solutions; (5) Combination of Ra-226 with conventional explosives (Dirty Bomb).This paper assesses the risk (R) of such criminal acts in terms of: (a) Probability of terrorist motivation deploying a certain attack mode T; (b) Probability of success by the terrorists for the selected attack mode T; (c) Primary damage consequence (C) to the attacked target (activity, dose); (d) Secondary damage consequence (C') to the attacked target (psychological and socio-economic effects); (e) Probability that the consequences (C, C') cannot be brought under control, resulting in a failure to manage successfully the emergency situation due to logistical and/or technical deficits in implementing adequate countermeasures. Extensive computer modelling is used to determine the potential impact of such a criminal attack on directly affected victims and on the environment.

  14. Measuring and Modeling Naturally Occurring Radioactive Material: Interpreting the Relationship Between the Natural Radionuclides Present

    SciTech Connect

    Lombardo, A.J.; Mucha, A.F.

    2008-07-01

    The regulatory release of sites and facilities (property) for restricted or unrestricted use has evolved beyond prescribed levels to model-derived dose and risk based limits. Dose models for deriving corresponding soil and structure radionuclide concentration guidelines are necessarily simplified representations of complex processes. A conceptual site model is often developed to present a reasonable and somewhat conservative representation of the physical and chemical properties of the impacted material. Dose modeling software is then used to estimate resulting dose and/or radionuclide specific acceptance criteria (activity concentrations). When the source term includes any or all of the uranium, thorium or actinium natural decay series radionuclides the interpretation of the relationship between the individual radionuclides of the series is critical to a technically correct and complete assessment of risk and/or derivation of radionuclide specific acceptance criteria. Unlike man-made radionuclides, modeling and measuring naturally occurring radioactive material (NORM) and technologically enhanced NORM (TENORM) source terms involves the interpretation of the relationship between the radionuclide present, e.g., secular equilibrium, enrichment, depletion or transient equilibrium. Isotopes of uranium, radium, and thorium occur in all three natural decay series. Each of the three series also produces a radon gas isotope as one of its progeny. In nature, the radionuclides in the three natural decay series are in a state that is approaching or has achieved secular equilibrium, in which the activities of all radionuclides within each series are nearly equal. However, ores containing the three natural decay series may begin in approximate secular equilibrium, but after processing, equilibrium may be broken and certain elements (and the radioactive isotopes of that element) may be concentrated or removed. Where the original ore may have contained one long chain of natural

  15. Natural analogue studies of the role of colloids, natural organics and microorganisms on radionuclide transport

    SciTech Connect

    McCarthy, J.F.

    1994-10-01

    Colloids may be important as a geochemical transport mechanism for radionuclides at geological repositories if they are (1) present in the groundwater, (2) stable with respect to both colloidal and chemical stabilities, (3) capable of adsorbing radionuclides, especially if the sorption is irreversible, and (4) mobile in the subsurface. The available evidence from natural analogue and other field studies relevant to these issues is reviewed, as is the potential role of mobile microorganisms ({open_quotes}biocolloids{close_quotes}) on radionuclide migration. Studies have demonstrated that colloids are ubiquitous in groundwater, although colloid concentrations in deep, geochemically stable systems may be too low to affect radionuclide transport. However, even low colloid populations cannot be dismissed as a potential concern because colloids appear to be stable, and many radionuclides that adsorb to colloids are not readily desorbed over long periods. Field studies offer somewhat equivocal evidence concerning colloid mobility and cannot prove or disprove the significance of colloid transport in the far-field environment. Additional research is needed at new sites to properly represent a repository far-field. Performance assessment would benefit from natural analogue studies to examine colloid behavior at sites encompassing a suite of probable groundwater chemistries and that mimic the types of formations selected for radioactive waste repositories.

  16. Investigation of radionuclide distribution in soil particles in different landscapes

    NASA Astrophysics Data System (ADS)

    Shkinev, V. M.; Korobova, E. M.; Linnik, V. G.

    2012-04-01

    Russian and foreign publications have been analyzed for understanding the role of micro- and nano- particles in distribution and migration of technogenic elements in soils in different landscape conditions. A technique for application of various fractionation methods to separate and study -particles of different size down to micro- and nano-level has been developed. The dry sit method on the first stage of particle separation is recommend to be followed by the membrane filtration method. For obtaining more comprehensive information, combinations of fractionation technique should be chosen taking into account that (1) the efficiency of particles' separation using subsequent technique would be higher than using the preceding one; (2) separation methods should preferably be based on different principles (separation according size, density, charge etc.); (3) initial fractionation should separate particles according to their size, that makes possible to create an even scale for various samples. A study of distribution and balance of technogenic radionuclides' in soil particles of the size intervals 1.0—0.25, 0.25-0.1, 0.1-0.05, 0.05-0.01, 0.01-0.005, 0.005-0.001 and <0.001 mm in the Yenisey flood plain landscapes proved a significant role of both the particle size and the portion of contaminated fraction in contribution to the total radionuclide inventory in the soil layers. Contribution of the silt particles (0,05-0,01 mm) to Cs-137 contamination ranged from 26 to 33,8%, 45% maximum due to "optimal" combination of both factors. Clay fraction was responsible for approximately 30% of Cs-137 contained in soil horizons due to higher sorption capacity. Relatively high correlation between the activity of 152,154Eu and 60 and the content of silt and clay allowed suggesting their incorporation mainly in clay fraction. Selected experimental plots near the Kola NPP (northern taiga) were used to compare soil particles (fractions 140-71; 71-40 and < 40 µm) in their ability to

  17. Subcellular distribution and translocation of radionuclides in plants

    SciTech Connect

    Gouthu, S.; Weginwar, R.; Arie, Tsutomu; Ambe, Shizuko; Ozaki, Takuo; Enomoto, Shuichi; Ambe, Fumitoshi; Yamaguchi, Isamu

    1999-09-01

    The subcellular distribution of radionuclides in Glycine max Merr. (soybean) and Cucumis sativus L. (cucumber) and translocation of plant absorbed radionuclides with growth in soybean were studied. More than 60% of cellular incorporated Rb{sup {minus}83}, Sr{sup {minus}85}, Mn{sup {minus}54}, Nb{sup {minus}95}, and Se{sup {minus}75} remained in the supernatant fraction; 55% and 20% of Cr{sup {minus}51} was bound to soybean and cucumber cell wall fractions, respectively; 70% or more of Be{sup {minus}7}, Y{sup {minus}88}, and Fe{sup {minus}59} was fixed in the chloroplast fraction; and approx. 10% of Sc{sup {minus}46}, Fe{sup {minus}59}, V{sup {minus}48}, and As were fixed in the mitochondrial fraction. Translocation of nuclides within the soybean plant at different stages of growth has been determined. Vanadium, Y{sup {minus}88}, Be{sup {minus}7}, Se{sup {minus}75}, Nb{sup {minus}95}, Sc{sup {minus}46}, Cr{sup {minus}51}, and Zr{sup {minus}88} were predominantly accumulated in the root. Although the total percentage of plant uptake of Sc{sup {minus}46}, Zr{sup {minus}88}, Nb{sup {minus}95}, Sc{sup {minus}46}, and Cr{sup {minus}51} was high, because of low mobility and translocation to shoot, their accumulation in the fruit fraction was negligible. The translocation of mobile nuclides in plants was demonstrated clearly by Rb{sup {minus}83}, Zn{sup {minus}65}, and Fe{sup {minus}59}. Data on the nuclide fraction mobilized from vegetative parts into edible parts was used to assess the percentage of accumulated radionuclides in plants that may reach humans through beans.

  18. Edaphic factors affecting the vertical distribution of radionuclides in the different soil types of Belgrade, Serbia.

    PubMed

    Dragović, Snežana; Gajić, Boško; Dragović, Ranko; Janković-Mandić, Ljiljana; Slavković-Beškoski, Latinka; Mihailović, Nevena; Momčilović, Milan; Ćujić, Mirjana

    2012-01-01

    The specific activities of natural radionuclides ((40)K, (226)Ra and (232)Th) and Chernobyl-derived (137)Cs were measured in soil profiles representing typical soil types of Belgrade (Serbia): chernozems, fluvisols, humic gleysols, eutric cambisols, vertisols and gleyic fluvisols. The influence of soil properties and content of stable elements on radionuclide distribution down the soil profiles (at 5 cm intervals up to 50 cm depth) was analysed. Correlation analysis identified associations of (40)K, (226)Ra and (137)Cs with fine-grained soil fractions. Significant positive correlations were found between (137)Cs specific activity and both organic matter content and cation exchange capacity. Saturated hydraulic conductivity and specific electrical conductivity were also positively correlated with the specific activity of (137)Cs. The strong positive correlations between (226)Ra and (232)Th specific activities and Fe and Mn indicate an association with oxides of these elements in soil. The correlations observed between (40)K and Cr, Ni, Pb and Zn and also between (137)Cs and Cd, Cr, Pb and Zn could be attributed to their common affinity for clay minerals. These results provide insight into the main factors that affect radionuclide migration in the soil, which contributes to knowledge about radionuclide behaviour in the environment and factors governing their mobility within terrestrial ecosystems. PMID:22072061

  19. Calculation of distribution coefficients for radionuclides in soils and sediments

    SciTech Connect

    Puigdomenech, I.; Bergstroem, U.

    1995-01-01

    The turnover of radionuclides in parts of the biosphere is usually modeled by use of a sorption distribution coefficient, K{sub d}. Its value has a large influence on calculated concentrations of long-lived radionuclides found in reservoirs, which are important for doses to humans. Sorption is due to several processes and a variety of physical and chemical interactions. In the commonly used K{sub d}-methodology. however, these processes were usually not considered explicitly. Additionally, many K{sub d} values were obtained from laboratory experiments from the geosphere, the conditions of which differ from those prevailing in the biosphere. The main objective of this work was to extend the knowledge about the theoretical background for calculation of K{sub d} values. To achieve this objective, theoretical models for ion exchange and surface complexation were adapted to simulation under biospheric conditions. Elements studied were Cs, Ra, Np, U, and Pu. The results show that a triple-layer surface complexation model may be used to estimate K{sub d} values for actinides as functions of some chemical parameters, such as pH and the redox potential (E{sub H}). An area of application is performance assessment of radioactive waste repositories. 59 refs., 7 figs., 3 tabs.

  20. Calculation of distribution coefficients for Radionuclides in soils and sediments

    SciTech Connect

    Puigdomenech, I.; Bergstrom, U.

    1995-10-01

    The turnover of radionuclides in parts of the biosphere is usually modeled by use of a sorption distribution coefficient, K{sub a}. Its value has a large influence on calculated concentrations of long-lived radionuclides found in reservoirs, which are important for doses to humans. Sorption is due to several processes and a variety of physical and chemical interactions (e.g., surface complexation and ion exchange). In the commonly used K{sub d}-methodology, however, these processes were usually not considered explicitly. Additionally, many K{sub d} values were obtained from laboratory experiments or from the geosphere, the conditions of which differ from those prevailing in the biosphere. The main objective of this work was to extend the knowledge about the theoretical background for calculation of K{sub d} values. To achieve this objective, theoretical models for ion exchange and surface complexation were adapted to simulation under biospheric conditions. Elements studied were Cs, Ra, Np, U and Pu. The results show that a triple-layer surface complexation model may be used to estimate K{sub d} values for actinides as functions of some chemical parameters, such as pH and the redox potential (E{sub H}). An area of application is performance assessment of radioactive waste repositories.

  1. EVALUATING MONITORED NATURAL ATTENUATION FOR RADIONUCLIDE & ORGANIC CONTAMINATION IN GROUNDWATER (SALT LAKE CITY, UT)

    EPA Science Inventory

    Monitored Natural Attenuation (MNA) for radionuclides and inorganic contaminants is dependent on naturally occurring processes in the subsurface that act without human intervention to reduce the mass, toxicity, mobility, volume or concentration of contaminants. EPA is developing ...

  2. Natural and anthropogenic radionuclide activity concentrations in the New Zealand diet.

    PubMed

    Pearson, Andrew J; Gaw, Sally; Hermanspahn, Nikolaus; Glover, Chris N

    2016-01-01

    To support New Zealand's food safety monitoring regime, a survey was undertaken to establish radionuclide activity concentrations across the New Zealand diet. This survey was undertaken to better understand the radioactivity content of the modern diet and also to assess the suitability of the current use of milk as a sentinel for dietary radionuclide trends. Thirteen radionuclides were analysed in 40 common food commodities, including animal products, fruits, vegetables, cereal grains and seafood. Activity was detected for (137)Caesium, (90)Strontium and (131)Iodine. No other anthropogenic radionuclides were detected. Activity concentrations of the three natural radionuclides of Uranium and the daughter radionuclide (210)Polonium were detected in the majority of food sampled, with a large variation in magnitude. The maximum activity concentrations were detected in shellfish for all these radionuclides. Based on the established activity concentrations and ranges, the New Zealand diet contains activity concentrations of anthropogenic radionuclides far below the Codex Alimentarius guideline levels. Activity concentrations obtained for milk support its continued use as a sentinel for monitoring fallout radionuclides in terrestrial agriculture. The significant levels of natural and anthropogenic radionuclide activity concentrations detected in finfish and molluscs support undertaking further research to identify a suitable sentinel for New Zealand seafood monitoring. PMID:26094571

  3. Environmental impact of natural radionuclides from a coal-fired power plant in Spain.

    PubMed

    Charro, Elena; Peña, Víctor

    2013-01-01

    This paper is a study of the radiological impact of a coal-fired power plant in Spain. Activity concentrations of six natural radionuclides were determined in coal, ash, mine wastes and sediments by gamma-ray spectrometry. The average activity concentrations of (238)U, (226)Ra, (224)Ra, (210)Pb, (232)Th and (40)K in coal were 24, 30, 28, 41, 23 and 242 Bq kg(-1)  and in ash were 103, 128, 101, 124, 88 and 860 Bq kg(-1), respectively. The enrichment factor, radium equivalent activity and alpha index in the ash sample have been estimated. For the five waste pile samples, the absorbed dose rate was higher than the world average dose rate (60 nGy h(-1)). The dependence of radionuclide concentration on the grain size of nine sediments was also studied. The analysis of the radionuclides in waste and sediment samples will demonstrate the distribution and mobility of these elements through the environment, where a potential risk of contamination can be detected. PMID:22807496

  4. Evaluation of natural radionuclides in Brazilian underground mines

    NASA Astrophysics Data System (ADS)

    Santos, T. O.; Rocha, Z.; Vasconcelos, V.; Lara, E. G.; Palmieri, H. E. L.; Cruz, P.; Gouvea, V. A.; Siqueira, J. B.; Oliveira, A. H.

    2015-11-01

    Mineral processing releases long and short half-life radionuclides generating potential exposure to miners. They are internally exposed to radon, thoron and their short-life decay products and, externally, to the gamma emitters scattered in the rock and dust of the mine. Concerning to radiological hazards to workers, this paper focuses on the characterization of the natural radioactivity in the Brazilian underground mines. The radon and its progeny concentrations were measured by using AlphaGUARD and DOSEman detectors, respectively. Radon concentration measurement in groundwater was performed by using RAD7 detector. The 238U and 232Th activity concentration in ore and soil samples were determined by ICPMS. Gamma spectrometry was used to determined 226Ra, 228Ra and 40K activity concentrations. The average radon concentration ranged from 113 to 4964 Bq m-3 and the average Equilibrium Equivalent Concentration varied from 76 to 1174 Bq m-3. Based on these data, the total annual effective dose for the miners was estimated. The results suggest the need of establishing monitoring and control procedures in some mines.

  5. Heat distribution by natural convection

    SciTech Connect

    Balcomb, J.D.

    1985-01-01

    Natural convection can provide adequate heat distribution in many situtations that arise in buildings. This is appropriate, for example, in passive solar buildings where some rooms tend to be more strongly solar heated than others or to reduce the number of heating units required in a building. Natural airflow and heat transport through doorways and other internal building apertures is predictable and can be accounted for in the design. The nature of natural convection is described, and a design chart is presented appropriate to a simple, single-doorway situation. Natural convective loops that can occur in buildings are described and a few design guidelines are presented.

  6. Committed effective dose from naturally occuring radionuclides in shellfish

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Wahib, Norfadira Binti; Amin, Yusoff Mohd.; Bradley, D. A.

    2013-07-01

    Recognizing their importance in the average Malaysian daily diet, the radioactivity concentrations in mollusc- and crustacean-based food have been determined for key naturally occuring radionuclides. Fresh samples collected from various maritime locations around peninsular Malaysia have been processed using standard procedures; the radionuclide concentrations being determined using an HPGe γ-ray spectrometer. For molluscs, assuming secular equilibrium, the range of activities of 238U (226Ra), 232Th (228Ra) and 40K were found to be 3.28±0.35 to 5.34±0.52, 1.20±0.21 to 2.44±0.21 and 118±6 to 281±14 Bq kg-1 dry weight, respectively. The respective values for crustaceans were 3.02±0.57 to 4.70±0.52, 1.38±0.21 to 2.40±0.35 and 216±11 to 316±15 Bq kg-1. The estimated average daily intake of radioactivity from consumption of molluscs are 0.37 Bq kg-1 for 238U (226Ra), 0.16 Bq kg-1 for 232Th (228Ra) and 18 Bq kg-1 for 40K; the respective daily intake values from crustaceans are 0.36 Bq kg-1, 0.16 Bq kg-1 and 23 Bq kg-1. Associated annual committed effective doses from molluscs are estimated to be in the range 21.3 to 34.7 μSv for 226Ra, 19.3 to 39.1 μSv for 228Ra and 17.0 to 40.4 μSv for 40K. For crustaceans, the respective dose ranges are 19.6 to 30.5 μSv, 22.0 to 38.4 μSv and 31.1 to 45.5 μSv, being some several times world average values.

  7. DISTRIBUTION AND RANGE OF RADIONUCLIDE SORPTION COEFFICIENTS IN A SAVANNAH RIVER SITE SUBSURFACE: STOCHASTIC MODELING CONSIDERATIONS

    SciTech Connect

    Kaplan, D.; et. al

    2010-01-11

    The uncertainty associated with the sorption coefficient, or K{sub d} value, is one of the key uncertainties in estimating risk associated with burying low-level nuclear waste in the subsurface. The objective of this study was to measure >648 K{sub d} values and provide a measure of the range and distribution (normal or log-normal) of radionuclide K{sub d} values appropriate for the E-Area disposal site, within the Savannah River Site, near Aiken South Carolina. The 95% confidence level for the mean K{sub d} was twice the mean in the Aquifer Zone (18-30.5 m depth), equal to the mean for the Upper Vadose Zone (3.3-10 m depth), and half the mean for the Lower Vadose Zone (3.10-18 m depth). The distribution of K{sub d} values was log normal in the Upper Vadose Zone and Aquifer Zone, and normal in the Lower Vadose Zone. To our knowledge, this is the first report of natural radionuclide Kd variability in the literature. Using ranges and distribution coefficients that are specific to the hydrostratigraphic unit improved model accuracy and reduced model uncertainty. Unfortunately, extension of these conclusions to other sites is likely not appropriate given that each site has its own sources of hydrogeological variability. However, this study provides one of the first examples of the development stochastic ranges and distributions of K{sub d} values for a hydrological unit for stochastic modeling.

  8. Investigating incorporation and distribution of radionuclides in trinitite.

    PubMed

    Belloni, F; Himbert, J; Marzocchi, O; Romanello, V

    2011-09-01

    Most of the surface explosions in nuclear tests have released radioactivity to the environment in the form of bulk glassy materials originating from the melting of sandy soil in the neighbourhood of ground zero. In view of clarifying issues concerning the mechanism of formation and the radiological impact of these materials, we investigated incorporation and volume distribution of radionuclides in a typical fragment of trinitite, the glassy substance generated following the first nuclear test (Trinity Site, New Mexico, 1945). Specific activities were determined by γ-spectrometry for the most significant fission and activation products. In particular, (152)Eu activity was used to estimate the original point of collection of the sample with respect to ground zero. After embedding in an epoxy resin, the sample was then sliced to perform cross-sectional β- and α-autoradiograph. α-spectrometry was also carried out on a fine powder obtained by surface abrasion. In the β-autoradiography, hot spots were distinguishable in the proximity of the blast side, over a 1000 times less intense background of sand activation products. Also α-contamination (from (239+240)Pu and (241)Am) was mostly concentrated within the superficial layer, in a fraction of only 20% of the overall volume of the sample, exhibiting a discontinuous, droplet-like distribution. This evidence would partially support a recent hypothesis on trinitite formation according to which most of the glass layer was formed not on the ground but by a rain of material injected into the fireball that melted, fell back, and collected on a bed of already fused sand. PMID:21636184

  9. Abundances of Natural Radionuclides (40K, 238U, 232Th) in Hanford and Rifle Integrated Field Research Challenge Site Sediments and the Application to the Estimation of Grain Size Distributions

    NASA Astrophysics Data System (ADS)

    Draper, K.; Ward, A. L.; Yabusaki, S.; Murray, C. J.; Greenwood, J.

    2009-12-01

    The distribution and geometry of lithofacies impact groundwater flow and solute spreading but are difficult to characterize at the scale controlling transport. We hypothesize that differences in γ-ray activity resulting from the natural distribution of 40K, 238U, and 232Th (K, U, T) are due to hydraulic separation and sorting and can be used to infer grain-size distributions at the scale of borehole γ-ray logs. The objective of this study was to investigate the feasibility of using γ-ray spectra to detect differences in grain size distributions as a means of characterizing small-scale variations in flow and reactive transport properties. The γ-ray spectra of whole and fractionated sediments from the Hanford and Old Rifle IFRC sites were characterized along with their grain size distributions. In the Hanford sediments, the abundance of K, U, and T was strongly correlated with the extent of weathering and with mean grain size. Hanford clay showed concentrations of 4%, 5.5 ppm, and 6.5 ppm for K, U, and T respectively. An increase in geometric mean diameter from 0.02 mm (clay) to 45.25 mm (very coarse gravel) showed increases in concentrations of 70% for K, 76% for U, and 83% for T. Old Rifle sediments showed no correlation between grain size and K, but there was an 81% increase in U and a 73 % increase in T. Cross plots of Th/U and Th/K also show strong correlations with grain size. The enrichment of natural isotopes with decreasing grain size is likely due to the increase in specific surface area. Thus, borehole γ-ray spectra could have a much wider application in characterizing grain separation and sorting and ultimately flow and reactive transport properties.

  10. Radionuclide releases from natural analogues of spent nuclear fuel

    SciTech Connect

    Curtis, D.B.; Fabryka-Martin, J.; Dixon, P.; Aguilar, R.; Rokop, D.; Cramer, J.

    1993-12-31

    Measures of {sup 99}Tc, {sup 129}I, {sup 239}Pu and U concentrations in rock samples from uranium deposits at Cigar Lake and Koongarra have been used to study processes of radionuclide release from uranium minerals. Rates of release have been immeasurably slow at Cigar Lake. At Koongarra release rates appear to have been faster, producing small deficiencies of {sup 99}Tc, and larger ones of {sup 129}I. The inferred differences in radionuclide release rates are consistent with expected differences in uranium mineral degradation rates produced by the differing hydrogeochemical environments at the two sites.

  11. Modeling Natural Variation through Distribution

    ERIC Educational Resources Information Center

    Lehrer, Richard; Schauble, Leona

    2004-01-01

    This design study tracks the development of student thinking about natural variation as late elementary grade students learned about distribution in the context of modeling plant growth at the population level. The data-modeling approach assisted children in coordinating their understanding of particular cases with an evolving notion of data as an…

  12. Hydrogeological interpretation of natural radionuclide contents in Austrian groundwaters

    NASA Astrophysics Data System (ADS)

    Schubert, Gerhard; Berka, Rudolf; Hörhan, Thomas; Katzlberger, Christian; Landstetter, Claudia; Philippitsch, Rudolf

    2010-05-01

    The Austrian Agency for Health and Food Safety (AGES) stores comprehensive data sets of radionuclide contents in Austrian groundwater. There are several analyses concerning Rn-222, Ra-226, gross alpha and gross beta as well as selected analyses of Ra-228, Pb-210, Po-210, Uranium and U-234/U-238. In a current project financed by the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management, AGES and the Geological Survey of Austria (GBA) are evaluating these data sets with regard to the geological backgrounds. Several similar studies based on groundwater monitoring have been made in the USA (for instance by Focazio, M.J., Szabo, Z., Kraemer, T.F., Mullin, A.H., Barringer, T.H., De Paul, V.T. (2001): Occurrence of selected radionuclides in groundwater used for drinking water in the United States: a reconnaissance survey, 1998. U.S. Geological Survey Water-Resources Investigations Report 00-4273). The geological background for the radionuclide contents of groundwater will be derived from geological maps in combination with existing Thorium and Uranium analyses of the country rocks and stream-sediments and from airborne radiometric maps. Airborne radiometric data could contribute to identify potential radionuclide hot spot areas as only airborne radiometric mapping could provide countrywide Thorium and Uranium data coverage in high resolution. The project will also focus on the habit of the sampled wells and springs and the hydrological situation during the sampling as these factors can have an important influence on the Radon content of the sampled groundwater (Schubert, G., Alletsgruber, I., Finger, F., Gasser, V., Hobiger, G. and Lettner, H. (2010): Radon im Grundwasser des Mühlviertels (Oberösterreich) Grundwasser. - Springer (in print). Based on the project results an overview map (1:500,000) concerning the radionuclide potential should be produced. The first version should be available in February 2011.

  13. Different sources of suspended sediment according to particle size determined by natural radionuclides

    NASA Astrophysics Data System (ADS)

    Mizugaki, S.; Ohtsuka, J.; Maruyama, M.; Hamamoto, S.; Murakami, Y.

    2012-12-01

    Extensive human activity and climate change have given great impacts on the sediment balance and connectivity between fluvial and coastal systems, causing sediment-related problems such as sedimentation in reservoir, coastal erosion and water pollution by prolonged turbid water. The dynamics of suspended sediment is one of the most important issues in watershed and coastal management. Suspended sediment load transported to ocean by a river commonly represents a mixture of sediments delivered from different locations and source types within the contributing catchment. In our previous study, we have found that the three natural radionuclides are available to discriminate the source areas of suspended sediment represented by six different bed rock type (sedimentary rock, accretionary sedimentary rock, accretionary basalt block, accretionary volcanic rock, plutonic rock and metamorphic rock), and that the contribution of each source areas to suspended sediment can be estimated (Mizugaki et al., 2012). To elucidate the sources of suspended sediment from mountain to coastal area, the fingerprinting was conducted using natural radionuclide tracers across a couple of adjacent watersheds, the Saru River and Mu River watersheds in central Hokkaido, northern Japan. We collected suspended sediments at outlets of the 13 sub-catchments (0.7-27.2 km2) and 12 stream channels with mid- to large-scaled watershed areas (17-1,333 km2), deposited sediments across a dam reservoir and coastal sediments, in total 389 samples. For collected sediment samples, grain size distributions were measured by laser-diffraction particle size analyzer. The specific surface areas of the samples were estimated using their grain size distribution and the spherical approximation of the particles in each class. For fingerprint the source of suspended sediment, three natural radionuclide activities, 212Pb, 228Ac and 40K, were measured by gamma-ray spectrometry. Specific surface area of the sediment showed

  14. Natural radionuclides and toxic elements in transboundary rivers of Kazakhstan.

    PubMed

    Solodukhin, V; Poznyak, V; Kabirova, G; Stepanov, V; Ryazanova, L; Lennik, S; Liventsova, A; Bychenko, A; Zheltov, D

    2015-06-01

    The paper reports on the study of radionuclide and elemental composition of water, bottom sediment and soil samples collected at the border areas of the following transboundary rivers in Kazakhstan: Chagan, Ural, Ilek, Tobol, Ayat, Irtysh, Emel, Ili, Tekes, Shu, Karabalta, Talas and Syrdarya. The employed analyses include the following methods: instrumental gamma-ray spectrometry, radiochemical analysis, neutron activation analysis, XRF and the inductively coupled plasma mass spectrometry (ICP-MS). Evidence of water environment contamination with radionuclides and toxic elements has been revealed in many of the studied rivers both in Kazakhstan and in adjacent countries. Transboundary transfer of the contaminants is most likely related to local industry (uranium mining and processing) and the presence of radioactive substances in the river basins. PMID:25971346

  15. Assessment of doses and risk due to natural radionuclides in edible biota of Domiasiat, Meghalaya.

    PubMed

    Kumar, N; Chaturvedi, S S; Jha, S K

    2012-07-01

    A radiation dose assessment exercise was carried out for the edible biota Solanum nigrum, Carica papaya, Raphnus sativum and Phaseolus domesticus due to naturally available radionuclides (40)K, (238)U and (232)Th in the Domiasiat area in Meghalaya, India. The concentration of radionuclides in biota and corresponding soil was measured by the NaI(Tl) detector having a minimum detection limit (efficiency, 32.4%) and machine counting time of 3000 s. The obtained transfer factor for (40)K was 0.3061, 0.7163, 0.1988 and 0.1279, for (232)Th 0.0003, 2.22E-05, 2.71E-05 and 3.45E-05 and for (238)U 1.46E-05, 9.73E-05, 1.46E-05 and 3.11E-05 (ratio) in each biota, respectively. The detailed physiological and morphological study of the biota was carried out. The point source dose distribution (source↔target) hypothesis was applied for the radiation absorbed fraction. The generated data were modelled using FASSET and obtained un-weighted total dose was 1.78E-04, 6.84E-03, 8.46E-03 and 1.73E-04 μGy h(-1), respectively, finally compared with the IAEA and UNSCEAR data set for screening level dose risk assessment. PMID:22155750

  16. Using naturally occurring radionuclides to determine drinking water age in a community water system

    DOE PAGESBeta

    Waples, James T.; Bordewyk, Jason K.; Knesting, Kristina M.; Orlandini, Kent A.

    2015-07-22

    Drinking water quality in a community water system is closely linked to the age of water from initial treatment to time of delivery. However, water age is difficult to measure with conventional chemical tracers; particularly in stagnant water, where the relationship between disinfectant decay, microbial growth, and water age is poorly understood. Using radionuclides that were naturally present in source water, we found that measured activity ratios of 90Y/90Sr and 234Th/238U in discrete drinking water samples of known age accurately estimated water age up to 9 days old (σest: ± 3.8 h, P < 0.0001, r2 = 0.998, n =more » 11) and 25 days old (σest: ± 13.3 h, P < 0.0001, r2 = 0.996, n = 12), respectively. Moreover, 90Y-derived water ages in a community water system (6.8 × 104 m3 d–1 capacity) were generally consistent with water ages derived from an extended period simulation model. Radionuclides differ from conventional chemical tracers in that they are ubiquitous in distribution mains and connected premise plumbing. The ability to measure both water age and an analyte (e.g., chemical or microbe) in any water sample at any time allows for new insight into factors that control drinking water quality.« less

  17. Natural radionuclide uptake by mosses in eastern Serbia in 2008-2013.

    PubMed

    Čučulović, Ana Č; Sabovljević, Marko; Čučulović, Rodoljub Č; Veselinović, Dragan

    2016-03-01

    The results of the study on natural radionuclide content in 102 samples of the moss species randomly collected in 2008- 2013 at 30 locations of eastern Serbia are presented in the paper. The activity concentration values of 238U, 226Ra, 232Th, 40K, and 7Be determined by gamma spectrometry were within the intervals: 238U (1.1-50) Bq kg(-1), 226Ra (1.1-41) Bq kg(-1), 232Th (1.4-28) Bq kg(-1), 40K (64-484) Bq kg(-1) and 7Be (88-227) Bq kg(-1), not standing out of the average data reported for this region. The distribution of the obtained data for 226Ra, 232Th, and 238U activity concentration in the analysed mosses has shown values up to 10 Bq kg(-1) with frequencies 47.1 %, 54.9 % and 48.0 %, respectively. The obtained activity concentration values of primordial 40K and cosmogenic radionuclide 7Be were up to 500 Bq kg(-1) and about 90 % of all the results for 7Be uptake by mosses were in the 200-250 Bq kg(-1) concentration range. PMID:27092637

  18. Natural radionuclides in an eucalyptus forest located in the south of Spain

    NASA Astrophysics Data System (ADS)

    Vaca, F.; Manjón, G.; García-León, M.

    2001-06-01

    Eucalyptus forests can be considered as the main source of raw material for the pulp industry of Spain. This environment was selected for a radioactivity study because natural and artificial radionuclides can be transferred into the pulp mills, associated with raw material, wood and barks, where they are concentrated by industrial processes, becoming a cause of doses. Radionuclide concentration of natural radionuclides ( 238U, 234U, 228Th, 230Th, 232Th) were determined by alpha- and gamma-spectrometry. Well-established radiochemical procedures were applied to environmental samples in order to isolate these radionuclides. A comparison between 228Th activity, determined by gamma-spectrometry, and 232Th activity, determined by alpha-spectrometry, was used as quality control parameter for analyses. The concentration factors were finally evaluated from experimental data.

  19. Distribution and mode of occurrence of radionuclides in phosphogypsum derived from Aqaba and Eshidiya Fertilizer Industry, South Jordan

    USGS Publications Warehouse

    Al-Hwaiti, M. S.; Zielinski, R.A.; Bundham, J.R.; Ranville, J.F.; Ross, P.E.

    2010-01-01

    Phosphogypsum (PG) is a by-product of the chemical reaction called the "wet process" whereby sulphuric acid reacts with phosphate rock (PR) to produce phosphoric acid, needed for fertilizer production. Through the wet process, some impurities naturally present in the PR become incorporated in PG, including U decay-series radionuclides, are the main important concern which could have an effect on the surrounding environment and prevent its safe utilization. In order to determine the distribution and bioavailability of radionuclides to the surrounding environment, we used a sequential leaching of PG samples from Aqaba and Eshidiya fertilizer industry. The results showed that the percentages of 226Ra and 210Pb in PG are over those in the corresponding phosphate rocks (PG/PR), where 85% of the 226Ra and 85% of the 210Pb fractionate to PG. The sequential extraction results exhibited that most of 226Ra and 210Pb are bound in the residual phase (non-CaSO4) fraction ranging from 45-65% and 55%-75%, respectively, whereas only 10%-15% and 10%-20% respectively of these radionuclides are distributed in the most labile fraction. The results obtained from this study showed that radionuclides are not incorporated with gypsum itself and may not form a threat to the surrounding environment. ?? 2010 Science Press, Institute of Geochemistry, CAS and Springer Berlin Heidelberg.

  20. Natural radionuclides in seafood from the central Adriatic Sea (Italy).

    PubMed

    Desideri, D; Meli, M A; Roselli, C

    2011-02-01

    Activity concentrations of ²¹⁰Po, ²¹⁰Pb, and ⁴⁰K were measured in different samples of marine organisms from the central Adriatic Sea. The marine organisms were purchased from the local consumer market during all four seasons of the year to evaluate the spatial and temporal distribution of the natural radioactivity. The concentration trend is the following: ⁴⁰K > ²¹⁰Po > ²¹⁰Pb. ⁴⁰K concentration ranged between 54.9 and 235.9 Bq kg⁻¹ fresh weight, and the arithmetic mean of Pb concentration for all samples is <0.7 Bq kg⁻¹ fresh weight. Po activity concentration ranged between 0.3 and 44.6 Bq kg⁻¹ fresh weight; its arithmetic mean was 5.7 ± 7.2 Bq kg⁻¹ fresh weight. Among the pelagic species, anchovy displayed the highest polonium concentration. The data obtained depend upon the type of marine organism and the period of sampling. Committed effective dose due to ²¹⁰Po ingestion from marine food for individuals in the two different population groups was calculated to be 95.9 and 466.4 μSv y⁻¹, respectively. PMID:21399431

  1. Spatial distribution and risk assessment of radionuclides in soils around a coal-fired power plant: A case study from the city of Baoji, China

    SciTech Connect

    Dai, L.J.; Wei, H.Y.; Wang, L.Q.

    2007-06-15

    Coal burning may enhance human exposure to the natural radionuclides that occur around coal-fired power plants (CFPP). In this study, the spatial distribution and hazard assessment of radionuclides found in soils around a CFPP were investigated using statistics, geostatistics, and geographic information system (GIS) techniques. The concentrations of Ra-226, Th-232, and K-40 in soils range from 12.54 to 40.18, 38.02 to 72.55, and 498.02 to 1126.98 Bq kg{sup -1}, respectively. Ordinary kriging was carried out to map the spatial patterns of radionuclides, and disjunctive kriging was used to quantify the probability of radium equivalent activity (Ra{sub eq}) higher than the threshold. The maps show that the spatial variability of the natural radionuclide concentrations in soils was apparent. The results of this study could provide valuable information for risk assessment of environmental pollution and decision support.

  2. Spatial distribution and risk assessment of radionuclides in soils around a coal-fired power plant: A case study from the city of Baoji, China

    SciTech Connect

    Dai Lijun; Wei Haiyan . E-mail: yuxidlj@stu.snnu.edu.cn; Wang Lingqing

    2007-06-15

    Coal burning may enhance human exposure to the natural radionuclides that occur around coal-fired power plants (CFPP). In this study, the spatial distribution and hazard assessment of radionuclides found in soils around a CFPP were investigated using statistics, geostatistics, and geographic information system (GIS) techniques. The concentrations of {sup 226}Ra, {sup 232}Th, and {sup 40}K in soils range from 12.54 to 40.18, 38.02 to 72.55, and 498.02 to 1126.98 Bq kg{sup -1}, respectively. Ordinary kriging was carried out to map the spatial patterns of radionuclides, and disjunctive kriging was used to quantify the probability of radium equivalent activity (Ra{sub eq}) higher than the threshold. The maps show that the spatial variability of the natural radionuclide concentrations in soils was apparent. The results of this study could provide valuable information for risk assessment of environmental pollution and decision support.

  3. Radionuclides in the soil around the largest coal-fired power plant in Serbia: radiological hazard, relationship with soil characteristics and spatial distribution.

    PubMed

    Ćujić, Mirjana; Dragović, Snežana; Đorđević, Milan; Dragović, Ranko; Gajić, Boško; Miljanić, Šćepan

    2015-07-01

    Primordial radionuclides, (238)U, (232)Th and (40)K were determined in soil samples collected at two depths (0-10 and 10-20 cm) in the vicinity of the largest coal-fired power plant in Serbia, and their spatial distribution was analysed using ordinary kriging. Mean values of activity concentrations for these depths were 50.7 Bq kg(-1) for (238)U, 48.7 Bq kg(-1) for (232)Th and 560 Bq kg(-1) for (40)K. Based on the measured activity concentrations, the radiological hazard due to naturally occurring radionuclides in soil was assessed. The value of the mean total absorbed dose rate was 76.3 nGy h(-1), which is higher than the world average. The annual effective dose due to these radionuclides ranged from 51.4 to 114.2 μSv. Applying cluster analysis, correlations between radionuclides and soil properties were determined. The distribution pattern of natural radionuclides in the environment surrounding the coal-fired power plant and their enrichment in soil at some sampling sites were in accordance with dispersion models of fly ash emissions. From the results obtained, it can be concluded that operation of the coal-fired power plant has no significant negative impact on the surrounding environment with regard to the content of natural radionuclides. PMID:25716901

  4. Microbial transformations of natural organic compounds and radionuclides in subsurface environments

    SciTech Connect

    Francis, A.J.

    1985-10-01

    A major national concern in the subsurface disposal of energy wastes is the contamination of ground and surface waters by waste leachates containing radionuclides, toxic metals, and organic compounds. Microorganisms play an important role in the transformation of organic compounds, radionuclides, and toxic metals present in the waste and affect their mobility in subsurface environments. Microbial processes involved in dissolution, mobilization, and immobilization of toxic metals under aerobic and anaerobic conditions are briefly reviewed. Metal complexing agents and several organic acids produced by microbial action affect mobilization of radionuclides and toxic metals in subsurface environments. Information on the persistence of and biodegradation rates of synthetic as well as microbiologically produced complexing agents is scarce but important in determining the mobility of metal organic complexes in subsoils. Several gaps in knowledge in the area of microbial transformation of naturally occurring organics, radionuclides, and toxic metals have been identified, and further basic research has been suggested. 31 refs., 1 fig., 3 tabs.

  5. Study of natural radionuclide and absorbed gamma dose in Ukhimath area of Garhwal Himalaya, India.

    PubMed

    Rautela, B S; Yadav, M; Bourai, A A; Joshi, V; Gusain, G S; Ramola, R C

    2012-11-01

    Natural radiation is the largest contributor to the collective radiation dose of the world population. It is widely distributed in different geological formations such as soil, rocks, air and groundwater. In the present investigation, (226)Ra, (232)Th and (40)K were measured in soil samples of the Ukhimath region of Garhwal Himalaya, India using NaI(Tl) gamma-ray spectrometry. The activity concentrations of naturally occurring radionuclides (226)Ra, (232)Th and (40)K were found to vary from 38.4 ± 6.1 to 141.7 ± 11.9 Bq kg(-1) with an average of 80.5 Bq kg(-1), 57.0 ± 7.5 to 155.9 ± 12.4 Bq kg(-1) with an average of 118.9 Bq kg(-1) and 9.0 ± 3.0 to 672.8 ± 25.9 Bq kg(-1) with an average of 341 Bq kg(-1), respectively. The total absorbed gamma dose rate varies from 70.4 to 169.1 nGy h(-1) with an average of 123.4 nGy h(-1). This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details. PMID:22908360

  6. Natural radionuclides and plutonium in sediments from the western Arctic Ocean: Sedimentation rates and pathways of radionuclides

    USGS Publications Warehouse

    Huh, C.-A.; Pisias, N.G.; Kelley, J.M.; Maiti, T.C.; Grantz, A.

    1997-01-01

    Sediment cores collected during R.V. Polar Sea AOS94 expedition from the Chukchi Shelf to the North Poke were analyzed for several decay-series natural radionuclides and Pu isotopes to study sedimentation rates and pathways of radionuclides in the western Arctic Ocean. The measured sedimentation rates vary by more than three orders of magnitude along the transect, from 210Pb based rates of 200-700 cm kyr-1 over the Chukchi Shelf and 89 cm kyr-1 at the Chukchi Slope to 230Th-based rates of 0.02-0.3 cm kyr-1 at various settings in the deep basin. 230Th(ex) profiles in the central western Arctic Basin are characterized by a cyclic pattern and a pronounced sub-surface maximum superimposed on an overall decrease with depth. Sediment inventories of excess 210Pb and 230Th in the deep basin as a whole cannot account for their in situ production and 2610Pb fall-out. The opposite is true at the slope and shallower waters. We contend that, as with other ocean basins, boundary scavenging also exists in the Arctic Ocean. The broad continental shelves and the slope region may have the potential of removing all or moat of the particle-reactive radionuclides unaccounted for in the deep basin. The Pu isotope data are consistent with the notion of boundary scavenging. Sediment inventories and concentrations of Pu decrease rapidly offshore. Isotopic composition of Pu suggests mixing of fall-out Pu, which decreases with increasing latitudes, and fuels reprocessing Pu derived from the Russian and Atlantic sides of the Arctic Ocean. Although fuel reprocessing Pu has impinged on the Chukchi Slope, its existence over the Chukchi Shelf is not evident and probably overshadowed by fall-out Pu.

  7. Radiological Assessment of Natural and Artificial Radionuclides in Mission (Texas) Surface Soils via Gamma-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wahid, Kareem; Hannan, Mohammad; Nguyen, Nam

    2015-04-01

    Residents living near decommissioned chemical facilities in the city of Mission, Texas have been noted to complain of physiological abnormalities and health related problems associated with low dose radiation exposure. The purpose of this study was to quantify radioactivity levels in the entire Mission area by measuring natural and anthropogenic radionuclide concentrations in 30 representative surface soil samples through high-resolution gamma-ray spectroscopy. The mean specific activity concentrations for these radionuclides were similar to other comparable locations and followed an approximately normal distribution across the samples. In addition, radiological impact assessment factors such as the absorbed dose rate, annual effective dose, radium equivalent activity, and external radiation hazard index were calculated and found to be lower than recommended values, thereby signifying that there seems to be no potential radiological threat associated with Mission surface soils.

  8. Natural attenuation of metals and radionuclides: Report from a workshop held by Sandia National Laboratories

    SciTech Connect

    Brady, P.V.; Borns, D.J.

    1997-11-01

    Natural attenuation is increasingly applied to remediate contaminated soils and ground waters. Roughly 25% of Superfund groundwater remedies in 1995 involved some type of monitored natural attenuation, compared to almost none 5 years ago. Remediation by natural attenuation (RNA) requires clear evidence that contaminant levels are decreasing sufficiently over time, a defensible explanation of the attenuation mechanism, long-term monitoring, and a contingency plan at the very least. Although the primary focus of implementation has to date been the biodegradation of organic contaminants, there is a wealth of scientific evidence that natural processes reduce the bioavailability of contaminant metals and radionuclides. Natural attenuation of metals and radionuclides is likely to revolve around sorption, solubility, biologic uptake and dilution controls over contaminant availability. Some of these processes can be applied to actively remediate sites. Others, such as phytoremediation, are likely to be ineffective. RNA of metals and radionuclides is likely to require specialized site characterization to construct contaminant and site-specific conceptual models of contaminant behavior. Ideally, conceptual models should be refined such that contaminant attenuation can be confidently predicted into the future. The technical approach to RNA of metals and radionuclides is explored here.

  9. Using naturally occurring radionuclides to determine drinking water age in a community water system

    SciTech Connect

    Waples, James T.; Bordewyk, Jason K.; Knesting, Kristina M.; Orlandini, Kent A.

    2015-07-22

    Drinking water quality in a community water system is closely linked to the age of water from initial treatment to time of delivery. However, water age is difficult to measure with conventional chemical tracers; particularly in stagnant water, where the relationship between disinfectant decay, microbial growth, and water age is poorly understood. Using radionuclides that were naturally present in source water, we found that measured activity ratios of 90Y/90Sr and 234Th/238U in discrete drinking water samples of known age accurately estimated water age up to 9 days old (σest: ± 3.8 h, P < 0.0001, r2 = 0.998, n = 11) and 25 days old (σest: ± 13.3 h, P < 0.0001, r2 = 0.996, n = 12), respectively. Moreover, 90Y-derived water ages in a community water system (6.8 × 104 m3 d–1 capacity) were generally consistent with water ages derived from an extended period simulation model. Radionuclides differ from conventional chemical tracers in that they are ubiquitous in distribution mains and connected premise plumbing. The ability to measure both water age and an analyte (e.g., chemical or microbe) in any water sample at any time allows for new insight into factors that control drinking water quality.

  10. Analysis of natural radionuclides in soil samples of Purola area of Garhwal Himalaya, India.

    PubMed

    Yadav, Manjulata; Rawat, Mukesh; Dangwal, Anoop; Prasad, Mukesh; Gusain, G S; Ramola, R C

    2015-11-01

    Naturally occurring radioactive materials are widely spread in the earth's environment, being distributed in soil, rocks, water, air, plants and even within the human body. All of these sources have contributed to an increase in the levels of environmental radioactivity and population radiation doses. This paper presents the activity level due to the presence of (226)Ra, (232)Th and (40)K in soil samples of Purola area in Garhwal Himalaya region. The measured activity of (226)Ra, (232)Th and (40)K in collected soil samples of Purola was found to vary from 13±10 to 55±10 Bq kg(-1) with an average of 31±2 Bq kg(-1), 13±10 to 101±13 Bq kg(-1) with an average 30±3 Bq kg(-1) and 150±81 to 1310±154 Bq kg(-1) with an average 583±30 Bq kg(-1), respectively. The radium equivalent activity in collected soil samples was found to vary from 47 to 221 Bq kg(-1) with an average of 115 Bq kg(-1). The total absorbed gamma dose rate in this area was found to vary from 22 to 93 nGy h(-1) with an average of 55 nGy h(-1). The distribution of these radionuclides in the soil of study area is discussed in details. PMID:25935014

  11. Suspended sediment from different geological sources in a watershed determined by natural radionuclides

    NASA Astrophysics Data System (ADS)

    Mizugaki, S.; Abe, T.; Murakami, Y.; Kubo, M.; Maruyama, M.; Hamamoto, S.

    2011-12-01

    The geological setting is essential for occurrence of slope failure and landslide so that the geology may control the suspended sediment yield with different magnitude. In the Saru River watershed of central Hokkaido, northern Japan, the typhoon Etau in August 2003 brought heavy rainfall, causing the slope failure and landslide across the areas of various geologies and the highest sediment yield since 1960s. Prolonged sediment runoff has caused the serious problems in association with turbid water, sedimentation in the reservoir, and their impacts on fishery and ecology downstream. To clarify the suspended sediment sources within the Nukabira River watershed, a tributary of Saru River, hydrological monitoring of discharge and turbidity and fingerprinting technique using natural radionuclide were conducted during a heavy rainfall event in August 2010. GIS analysis for slope failure and landslide areas was also conducted to investigate the distribution of potential suspended sediment sources. The activity of radionuclides, including U-series, Th-series, cesium-137 and potassium-40 were determined by gamma ray spectrometry. Statistical analysis showed the best composite fingerprints of Pb-212, Ac-228 and K-40 to classify the suspended sediment sources into six geological units, which were sedimentary rock, plutonic rock, metamorphic rock and three types of cretaceous accretionary complex consist of sedimentary rock, basalt block and volcanic rock. The contribution of source group to suspended sediment was calculated according to the assumption that the Mahalanobis distance in tracer properties between sources and suspended sediment can represent relative contribution of the source. During the rainfall event on August 11, 2011, dominant source of suspended sediment was found to be the areas consist of metamorphic rock (31%), sedimentary rock (30%) and accretionary sedimentary rock (24%). GIS analysis showed the spatial distribution of slope failure and landslide within

  12. Natural radionuclides in bottled drinking waters produced in Croatia and their contribution to radiation dose.

    PubMed

    Rožmarić, Martina; Rogić, Matea; Benedik, Ljudmila; Strok, Marko

    2012-10-15

    Activity concentrations of (234)U, (238)U, (226)Ra, (228)Ra, (210)Po and (210)Pb in all Croatian bottled drinking natural spring and natural mineral water products, commercially available on the market, were determined. The samples originated from various geological regions of Croatia. Activity concentrations of measured radionuclides are in general decreasing in this order: (234)U>(238)U>(226)Ra>(228)Ra>(210)Pb>(210)Po and (226)Ra>(228)Ra>(234)U>(238)U>(210)Pb>(210)Po for natural spring and mineral waters, respectively. Based on the radionuclide activity concentrations average total annual effective ingestion doses for infants, children and adults, as well as contribution of each particular radionuclide to total dose, were assessed and discussed. The highest doses were calculated for children from 7 to 12 years of age, which makes them the most critical group of population. All values for each type of water, as well as for each population group, were well below the recommended reference dose level (RDL) of 0.1 mSv from one year's consumption of drinking water according to the European Commission recommendations from 1998. Contribution of each particular radionuclide to total doses varied among different water types and within each water type, as well as between different age groups, where the lowest contribution was found for uranium isotopes and the highest for (228)Ra. PMID:22906977

  13. Analogue validation study of natural radionuclide migration in crystalline rocks using uranium-series disequilibrium studies

    SciTech Connect

    Smellie, J.A.T.; MacKenzie, A.B.; Scott, R.D.

    1986-01-01

    Concentrations and isotope ratios of natural decay series radionuclides have been studied in three contrasting crystalline rock drill core sections intersecting water-conducting fractures deep in the bedrock. Radioactive disequilibria resulting from rock-water interactions were observed in two of the cores. These indicated uranium migration along distances of 40 cm or more on a timescale of 10/sup 6/ years in conjunction with thorium immobility under the same conditions. Fracture surface minerals showed a high affinity for radionuclide retardation and a limit of about 3 cm is suggested for the migration of radionuclides from fracture fluids into the saturated rock. This limit may correspond to enhanced matrix porosities resulting from earlier hydrothermal activity along the same channels.

  14. Assessment of spatial distribution of fallout radionuclides through geostatistics concept.

    PubMed

    Mabit, L; Bernard, C

    2007-01-01

    After introducing geostatistics concept and its utility in environmental science and especially in Fallout Radionuclide (FRN) spatialisation, a case study for cesium-137 ((137)Cs) redistribution at the field scale using geostatistics is presented. On a Canadian agricultural field, geostatistics coupled with a Geographic Information System (GIS) was used to test three different techniques of interpolation [Ordinary Kriging (OK), Inverse Distance Weighting power one (IDW1) and two (IDW2)] to create a (137)Cs map and to establish a radioisotope budget. Following the optimization of variographic parameters, an experimental semivariogram was developed to determine the spatial dependence of (137)Cs. It was adjusted to a spherical isotropic model with a range of 30 m and a very small nugget effect. This (137)Cs semivariogram showed a good autocorrelation (R(2)=0.91) and was well structured ('nugget-to-sill' ratio of 4%). It also revealed that the sampling strategy was adequate to reveal the spatial correlation of (137)Cs. The spatial redistribution of (137)Cs was estimated by Ordinary Kriging and IDW to produce contour maps. A radioisotope budget was established for the 2.16 ha agricultural field under investigation. It was estimated that around 2 x 10(7)Bq of (137)Cs were missing (around 30% of the total initial fallout) and were exported by physical processes (runoff and erosion processes) from the area under investigation. The cross-validation analysis showed that in the case of spatially structured data, OK is a better interpolation method than IDW1 or IDW2 for the assessment of potential radioactive contamination and/or pollution. PMID:17673340

  15. Radionuclide distributions and migration mechanisms at shallow land burial sites. 1982 annual report of research investigations on the distribution, migration and containment of radionuclides at Maxey Flats, Kentucky

    SciTech Connect

    Kirby, L.J.

    1984-02-01

    Subsurface waters at Maxey Flats are anoxic, have a high alkalinity and contain high concentrations of ferrous, sulfide and ammonium ions and organic carbon. The trench leachates are extremely variable in composition. Prominent radionuclides include /sup 3/H, /sup 60/Co, /sup 90/Sr, /sup 137/Cs, /sup 238/ /sup 239/ /sup 240/Pu and /sup 241/Am. A wide spectrum of dissolved organic compounds is present in the leachates, including EDTA, polar organics and decomposition products from the waste forms. Cobalt-60 and plutonium are present as EDTA complexes and /sup 90/Sr and /sup 137/Cs are associated with carboxylic acid type compounds. The chemistry of these waters changes drastically as they become oxic and plutonium becomes less mobile under these new conditions. Water enters the trenches by infiltration through the trench caps, through subsidence areas, and through interfaces between new landfill and the original soil. Lateral flow is very complex and slow, and apparently occurs mainly by fracture flow. The plastic infiltration barrier installed in 1981 to 1982 has been effective in reducing soil moisture if cracks and leaks are eliminated. To date, no direct evidence of radionuclide transport to offsite locations by subsurface flow has been confirmed. The offsite distribution of radionuclides, except for tritium, is comparable to the ambient fallout from nuclear weapons testing. Tritium concentrations in water offsite are orders of magnitude below MPC levels. 24 figures, 31 tables.

  16. Computation Of The Residual Radionuclide Activity Within Three Natural Waterways At The Savannah River Site

    SciTech Connect

    Hiergesell, R. A.; Phifer, M. A.

    2014-01-07

    In 2010 a Composite Analysis (CA) of the U.S. Department of Energy’s (DOE’s) Savannah River Site (SRS) was completed. This investigation evaluated the dose impact of the anticipated SRS End State residual sources of radionuclides to offsite members of the public. Doses were assessed at the locations where SRS site streams discharge into the Savannah River at the perimeter of the SRS. Although the model developed to perform this computation indicated that the dose constraint of 0.3 mSv/yr (30 mrem/yr), associated with CA, was not approached at the Points of Assessment (POAs), a significant contribution to the total computed dose was derived from the radionuclides (primarily Cs-137) bound-up in the soil and sediment of the drainage corridors of several SRS streams. DOE’s Low Level Waste Federal Review Group (LFRG) reviewed the 2010 CA and identified several items to be addressed in the SRS Maintenance Program. One of the items recognized Cs-137 in the Lower Three Runs (LTR) Integrator Operable Unit (IOU), as a significant CA dose driver. The item made the recommendation that SRS update the estimated radionuclide inventory, including Cs-137, in the LTR IOU. That initial work has been completed and its radionuclide inventory refined. There are five additional streams at SRS and the next phase of the response to the LFRG concern was to obtain a more accurate inventory and distribution of radionuclides in three of those streams, Fourmile Branch (FMB), Pen Branch (PB) and Steel Creek (SC). Each of these streams is designated as an IOU, which are defined for the purpose of this investigation as the surface water bodies and associated wetlands, including the channel sediment, floodplain sed/soil, and related biota. If present, radionuclides associated with IOUs are adsorbed to the streambed sediment and soils of the shallow floodplains that lie immediately adjacent to stream channels. The scope of this effort included the evaluation of any previous sampling and

  17. IMPACTS OF SOLUBILITY AND OTHER GEOCHEMICAL PROCESSES ON RADIONUCLIDE RETARDATION IN THE NATURAL SYSTEM

    SciTech Connect

    B. Arnold

    2005-08-02

    This report documents results and findings of a study of solubility/co-precipitation effects and enhanced sorption due to variations in redox conditions on radionuclide transport in the natural system (BSC 2005 [DIRS 173951]; BSC 2005 [DIRS 173859]) conducted in response to DOE Contracting Officer Authorization Letter 05-001, Item d (Mitchell 2005 [DIRS 173265]). The purpose of this study is to assess the potential impacts of precipitation and enhanced sorption due to variations in redox conditions on radionuclide transport in the saturated zone (SZ) at Yucca Mountain. The information presented in this report is intended to aid in assessing the conservatism in the SZ transport model for supporting the total system performance assessment (TSPA) calculations. A similar study was performed for the impact of solubility/precipitation on radionuclide transport in the unsaturated zone (UZ). However, because the unsaturated zone is under predominantly oxidizing conditions and that the radionuclides released from the engineered barrier system are not expected to precipitate in the UZ for the reasons described below, it was concluded that the effect on unsaturated zone transport is not significant to warrant a detailed study. Solubility limiting conditions for neptunium in the UZ are expected to be similar to the conditions for neptunium solubility in the waste emplacement drift invert, where Np{sub 2}O{sub 5} is recommended as the controlling solid phase (BSC 2005 [DIRS 174566], Section 6.6.1). Solubility limits for neptunium inside the waste package, however, are expected to be controlled by NpO{sub 2} (BSC 2005 [DIRS 174566], Section 6.6.1). The solubility limits for Np2O5 are generally much higher than for NpO{sub 2} (BSC 2005 [DIRS 174566], Tables 6.6-4 and 6.6-7). Therefore, the low concentrations of neptunium releases from waste packages are unlikely to be affected by solubility limits in the unsaturated zone. The SZ is part of the Lower Natural Barrier to the

  18. A dynamic model for evaluating radionuclide distribution in forests from nuclear accidents.

    PubMed

    Schell, W R; Linkov, I; Myttenaere, C; Morel, B

    1996-03-01

    The Chernobyl Nuclear Power Plant accident in 1986 caused radionuclide contamination in most countries in Eastern and Western Europe. A prime example is Belarus where 23% of the total land area received chronic levels; about 1.5 x 10(6) ha of forested lands were contaminated with 40--190 kBq m-2 and 2.5 x 10(4) ha received greater than 1,480 kBq m-2 of 137Cs and other long-lived radionuclides such as 90Sr and 239,240Pu. Since the radiological dose to the forest ecosystem will tend to accumulate over long time periods (decades to centuries), we need to determine what countermeasures can be taken to limit this dose so that the affected regions can, once again, safely provide habitat and natural forest products. To address some of these problems, our initial objective is to formulate a generic model, FORESTPATH, which describes the major kinetic processes and pathways of radionuclide movement in forests and natural ecosystems and which can be used to predict future radionuclide concentrations. The model calculates the time-dependent radionuclide concentrations in different compartments of the forest ecosystem based on the information available on residence half-times in two forest types: coniferous and deciduous. The results show that the model reproduces well the radionuclide cycling pattern found in the literature for deciduous and coniferous forests. Variability analysis was used to access the relative importance of specific parameter values in the generic model performance. The FORESTPASTH model can be easily adjusted for site-specific applications. PMID:8609024

  19. A dynamic model for evaluating radionuclide distribution in forests from nuclear accidents

    SciTech Connect

    Schell, W.R.; Linkov, I.; Myttenaere, C.

    1996-03-01

    The Chernobyl Nuclear Power Plant accident in 1986 caused radionuclide contamination in most countries in Eastern and Western Europe. A prime example is Belarus where 23% of the total land area received chronic levels; about 1.5 X 10{sup 6} ha of forested lands were contaminated with 40-190 kBq m{sup -2} and 2.5 X 10{sup 4} ha received greater than 1,480 kBq m{sup -2} of {sup 137}Cs and other long-lived radionuclides such as {sup 90}Sr and {sup 239,240}Pu. Since the radiological dose to the forest ecosystem will tend to accumulate over long time periods (decades to centuries), we need to determine what countermeasures can be taken to limit this dose so that the affected regions can, once again, safely provide habitat and natural forest products. To address some of these problems, our initial objective is to formulate a generic model, FORESTPATH, which describes the major kinetic processes and pathways of radionuclide movement in forests and natural ecosystems and which can be used to predict future radionuclide concentrations. The model calculates the time-dependent radionuclide concentrations in different compartments of the forest ecosystem based on the information available on residence half-times in two forest types: coniferous and deciduous. The results show that the model reproduces well the radionuclide cycling pattern found in the literature for deciduous and coniferous forests. Variability analysis was used to access the relative importance of specific parameter values in the generic model performance. The FORESTPASTH model can be easily adjusted for site-specific applications. 92 refs., 5 figs., 6 tabs.

  20. DISTRIBUTION AND RANGE OF RADIONUCLIDE SORPTIOIN COEFFICIENTS IN A SAVANNAH RIVER SITE SUBSURFACE: STOCHASTIC MODELING CONSIDERATIONS - 10259

    SciTech Connect

    Kaplan, D.

    2010-01-04

    The uncertainty associated with the sorption coefficient, or K{sub d} value, is one of the key uncertainties in estimating risk associated with burying low-level nuclear waste in the subsurface. The objective of this study was to measure >648 K{sub d} values and provide a measure of the range and distribution (normal or log-normal) of radionuclide K{sub d} values appropriate for the E-Area disposal site, within the Savannah River Site, near Aiken South Carolina. The 95% confidence level for the mean K{sub d} was twice the mean in the Aquifer Zone (18-30.5 m depth), equal to the mean for the Upper Vadose Zone (3.3-10 m depth), and half the mean for the Lower Vadose Zone (3.3-18 m depth). The distribution of K{sub d} values was log normal in the Upper Vadose Zone and Aquifer Zone, and normal in the Lower Vadose Zone. To our knowledge, this is the first report of natural radionuclide K{sub d} variability in the literature. Using ranges and distribution coefficients that are specific to the hydrostratigraphic unit improved model accuracy and reduced model uncertainty. Unfortunately, extension of these conclusions to other sites is likely not appropriate given that each site has its own sources of hydrogeological variability. However, this study provides one of the first examples of the development stochastic ranges and distributions of K{sub d} values for a hydrological unit for stochastic modeling.

  1. Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose.

    PubMed

    Patra, A C; Sahoo, S K; Tripathi, R M; Puranik, V D

    2013-09-01

    Gamma emitters were estimated in surface soils from a mineralized zone in Eastern India using high purity Germanium detector-based high resolution gamma spectrometry system. Activities of (238)U, (226)Ra, (232)Th, (235)U, (227)Th, (234 m)Pa, (210)Pb, (40)K, and (137)Cs were 79 ± 50, 81 ± 53, 65 ± 23, 4 ± 2, 5 ± 4, 92 ± 50, 97 ± 45, 517 ± 201, and 4 ± 2 Bq/kg, respectively. Most radionuclides were observed to follow log-normal distribution. The correlation between physicochemical properties of the samples, like pH, organic matter content, particle size, and moisture content were also studied. Activity ratios of (226)Ra/(238)U, (210)Pb/(226)Ra, and (227)Th/(235)U indicated deviation from secular equilibrium in some samples. The associated annual effective dose ranged from 0.07 to 0.24 mSv and the mean was calculated to be 0.12 ± 0.04 mSv for this region, indicating it to be one of normal natural background radiation. PMID:23456273

  2. Comparison of in situ and laboratory gamma spectroscopy of natural radionuclides in desert soil.

    PubMed

    Benke, R R; Kearfott, K J

    1997-08-01

    In situ and laboratory gamma spectroscopy were used to characterize natural background levels of radiation in the soil at eight sites around the Yucca Mountain Range. The purpose of this practical field analysis was to determine if published empirical in situ calibration factors would yield accurate quantitative specific activities (Bq kg(-1)) in a desert environment. Corrections were made to the in situ calibration factors to account for the on-axis response of a detector with a thin beryllium end window. The in situ gamma spectroscopy results were compared to laboratory gamma spectroscopy of soil samples gathered from each site. Five natural radionuclides were considered: 40K, 214Pb, 214Bi, 208Tl, and 228Ac. The in situ determined specific activities were consistently within +/-15% of the laboratory soil sample results. A quantitative discussion of the factors contributing to the uncertainty in the in situ and laboratory results is included. Analysis on the specific activity data using statistical hypothesis tests determined that three nuclides, 214Pb, 214Bi, and 228Ac showed a weak site dependence while the other two nuclides, 40K and 208Tl, did not exhibit a site dependence. Differing radiation background levels from site to site along with in situ and laboratory uncertainties in excess of 10% are two factors that account for the weak site dependence. Despite the good correlation between data, it was recommended that the in situ detector be calibrated by a detector-specific Monte Carlo code which would accurately model more complex geometries and source distributions. PMID:9228170

  3. DETERMINATION OF THE DISTRIBUTION AND INVENTORY OF RADIONUCLIDES WITHIN A SAVANNAH RIVER SITE WATERWAY

    SciTech Connect

    Hiergesell, R.; Phifer, M.

    2012-11-09

    An investigation was conducted to evaluate the radionuclide inventory within the Lower Three Runs (LTR) Integrator Operable Unit (IOU) at the U.S. Department of Energy’s (DOE’s) Savannah River Site (SRS). The scope of this effort included the analysis of previously existing sampling and analysis data as well as additional streambed and floodplain sampling and analysis data acquired to delineate horizontal and vertical distributions of the radionuclide as part of the ongoing SRS environmental restoration program, and specifically for the LTR IOU program. While cesium-137 (Cs-137) is the most significant and abundant radionuclide associated with the LTR IOU it is not the only radionuclide, hence the scope included evaluating all radionuclides present and includes an evaluation of inventory uncertainty for use in sensitivity and uncertainty analyses. The scope involved evaluation of the radionuclide inventory in the P-Reactor and RReactor cooling water effluent canal systems, PAR Pond (including Pond C) and the floodplain and stream sediment sections of LTR between the PAR Pond Dam and the Savannah River. The approach taken was to examine all of the available Sediment and Sediment/Soil analysis data available along the P- and R-Reactor cooling water re-circulation canal system, the ponds situated along those canal reaches and along the length of LTR below Par Pond dam. By breaking the IOU into a series of sub-components and sub-sections, the mass of contaminated material was estimated and a representative central concentration of each radionuclide was computed for each compartment. The radionuclide inventory associated with each sub-compartment was then aggregated to determine the total radionuclide inventory that represented the full LTR IOU. Of special interest was the inventory of Cs-137 due to its role in contributing to the potential dose to an offsite member of the public. The overall LTR IOU inventory of Cs-137 was determined to be 75.5 Ci, which is similar

  4. Determination of the Distribution and Inventory of Radionuclides within a Savannah River Site Waterway - 13202

    SciTech Connect

    Hiergesell, R.A.; Phifer, M.A.

    2013-07-01

    An investigation was conducted to evaluate the radionuclide inventory within the Lower Three Runs (LTR) Integrator Operable Unit (IOU) at the U.S. Department of Energy's (DOE's) Savannah River Site (SRS). The scope of this effort included the analysis of previously existing sampling and analysis data as well as additional stream bed and flood plain sampling and analysis data acquired to delineate horizontal and vertical distributions of the radionuclide as part of the ongoing SRS environmental restoration program, and specifically for the LTR IOU program. While cesium-137 (Cs-137) is the most significant and abundant radionuclide associated with the LTR IOU it is not the only radionuclide, hence the scope included evaluating all radionuclides present and includes an evaluation of inventory uncertainty for use in sensitivity and uncertainty analyses. The scope involved evaluation of the radionuclide inventory in the P-Reactor and R-Reactor cooling water effluent canal systems, PAR Pond (including Pond C) and the flood plain and stream sediment sections of LTR between the PAR Pond Dam and the Savannah River. The approach taken was to examine all of the available Sediment and Sediment/Soil analysis data available along the P- and R-Reactor cooling water re-circulation canal system, the ponds situated along those canal reaches and along the length of LTR below Par Pond dam. By breaking the IOU into a series of sub-components and sub-sections, the mass of contaminated material was estimated and a representative central concentration of each radionuclide was computed for each compartment. The radionuclide inventory associated with each sub-compartment was then aggregated to determine the total radionuclide inventory that represented the full LTR IOU. Of special interest was the inventory of Cs-137 due to its role in contributing to the potential dose to an offsite member of the public. The overall LTR IOU inventory of Cs-137 was determined to be 2.87 E+02 GBq, which is

  5. Concentrations and concentration factors of several anthropogenic and natural radionuclides in marine vertebrates and invertebrates. Final report

    SciTech Connect

    Noshkin, V.E.

    1985-07-17

    Literature is reviewed and summarized with regard to concentrations of several anthropogenic and natural radionuclides in biological organisms from marine environments. Reported concentration factors for these radionuclides in organisms are tabulated for marine fish and invertebrates from water masses affected by different source terms.

  6. Natural-series radionuclides in traditional aboriginal foods in tropical northern Australia: a review.

    PubMed

    Martin, Paul; Ryan, Bruce

    2004-02-26

    This paper gives a review of available information on natural-series radionuclides in traditional Aboriginal foods of northern Australia. Research on this topic has been carried out primarily for radiological impact assessment purposes in relation to uranium mining activities in the region. Many of the studies have concentrated on providing purely concentration data or concentration ratios, although more detailed uptake studies have been undertaken for freshwater mussels, turtles, and water lilies. The most-studied radionuclides are 238U and 226Ra. However, dose estimates based on current data highlight the importance of 210Po, particularly for the natural (nonmining-related) dose. Data on uptake by terrestrial flora and fauna are scarce in comparison with aquatic organisms, and this knowledge gap will need to be addressed in relation to planning for uranium minesite rehabilitation. PMID:15004321

  7. Assessment of radionuclide retardation: uses and abuses of natural analogue studies

    NASA Astrophysics Data System (ADS)

    McKinley, Ian G.; Russell Alexander, W.

    1993-06-01

    Various techniques which have been reported for the in situ determination of radionuclide sorption or retardation as part of natural analogue studies have been critically assessed. In particular cases, the tacit assumptions used to derive retardation data from field observations can be shown to be questionable or, indeed, totally incorrect. Some problems identified are due to ambiguous or inconsistent use of terminology, but a fundamental error which commonly arises is the failure to distinguish between sorption and precipitation — processes which are treated quite differently in transport models. Natural analogue studies can be used to test radionuclide migration models and their associated databases, but considerable efforts are required to adequately characterise the geochemical process occurring. Without such extensive studies, the general applicability of data produced is limited and claims to derive parameters usable in repository performance assessment should be treated with considerable caution.

  8. Natural Radionuclides and Isotopic Signatures for Determining Carbonaceous Aerosol Sources, Aerosol Lifetimes, and Washout Processes

    SciTech Connect

    Gaffney, Jeffrey

    2012-12-12

    This is the final technical report. The project description is as follows: to determine the role of aerosol radiative forcing on climate, the processes that control their atmospheric concentrations must be understood, and aerosol sources need to be determined for mitigation. Measurements of naturally occurring radionuclides and stable isotopic signatures allow the sources, removal and transport processes, as well as atmospheric lifetimes of fine carbonaceous aerosols, to be evaluated.

  9. Weathering products of basic rocks as sorptive materials of natural radionuclides

    SciTech Connect

    Omelianenko, B.I.; Niconov, B.S.; Ryzhov, B.I.; Shikina, N.D.

    1994-06-01

    The principal requirements for employing natural minerals as buffer and backfill material in high-level waste (HLW) repositories are high sorptive properties, low water permeability, relatively high thermal conductivity, and thermostability. The major task of the buffer is to prevent the penetration of radionuclides into groundwater. The authors of this report examined weathered basic rocks from three regions of Russia in consideration as a suitable radioactive waste barrier.

  10. Monitoring of radionuclides contamination of soils in Shatsk National Natural Park (Volyn region, Ukraine) during 1994-2001.

    PubMed

    Hrabovskyy, V; Dzendzelyuk, O; Katerynchuk, I; Furgala, Y

    2004-01-01

    The results of studies of radionuclide contamination of the soils in the western part of the territory of Shatsk National Natural Park (ShNNP), Volyn region, Ukraine, performed during 1994-2001 are presented. Based on the experimental results, the three-dimensional plot of the 137Cs density contamination for the soils at the territory under investigation has been constructed. The monitoring during 1994-2001 of the 137Cs vertical distributions in the different kinds of soils from the Park and the forecasting of the distribution changes of the depth down to 50 cm for the sod loamy sandy gleyed loamy sand soil of the Park up to 2086 have been performed. PMID:15162852

  11. Anthropogenic radionuclide fluxes and distribution in bottom sediments of the cooling basin of the Ignalina Nuclear Power Plant.

    PubMed

    Marčiulionienė, D; Mažeika, J; Lukšienė, B; Jefanova, O; Mikalauskienė, R; Paškauskas, R

    2015-07-01

    Based on γ-ray emitting artificial radionuclide spectrometric measurements, an assessment of areal and vertical distribution of (137)Cs, (60)Co and (54)Mn activity concentrations in bottom sediments of Lake Drūkšiai was performed. Samples of bottom sediments from seven monitoring stations within the cooling basin were collected in 1988-1996 and 2007-2010 (in July-August). For radionuclide areal distribution analysis, samples from the surface 0-5 cm layer were used. Multi sample cores sliced 2 cm, 3 cm or 5 cm thick were used to study the vertical distribution of radionuclides. The lowest (137)Cs activity concentrations were obtained for two stations that were situated close to channels with radionuclide discharges, but with sediments that had a significantly smaller fraction of organic matter related to finest particles and consequently smaller radionuclide retention potential. The (137)Cs activity concentration was distributed quite evenly in the bottom sediments from other investigated monitoring stations. The highest (137)Cs activity concentrations in the bottom sediments of Lake Drūkšiai were measured in the period of 1988-1989; in 1990, the (137)Cs activity concentrations slightly decreased and they varied insignificantly over the investigation period. The obtained (238)Pu/(239,240)Pu activity ratio values in the bottom sediments of Lake Drūkšiai represented radioactive pollution with plutonium from nuclear weapon tests. Higher (60)Co and (54)Mn activity concentrations were observed in the monitoring stations that were close to the impact zones of the technical water outlet channel and industrial rain drainage system channel. (60)Co and (54)Mn activity concentrations in the bottom sediments of Lake Drūkšiai significantly decreased when operations at both INPP reactor units were stopped. The vertical distribution of radionuclides in bottom sediments revealed complicated sedimentation features, which may have been affected by a number of natural and

  12. The enrichment of natural radionuclides in oil shale-fired power plants in Estonia--the impact of new circulating fluidized bed technology.

    PubMed

    Vaasma, Taavi; Kiisk, Madis; Meriste, Tõnis; Tkaczyk, Alan Henry

    2014-03-01

    Burning oil shale to produce electricity has a dominant position in Estonia's energy sector. Around 90% of the overall electric energy production originates from the Narva Power Plants. The technology in use has been significantly renovated - two older types of pulverized fuel burning (PF) energy production units were replaced with new circulating fluidized bed (CFB) technology. Additional filter systems have been added to PF boilers to reduce emissions. Oil shale contains various amounts of natural radionuclides. These radionuclides concentrate and become enriched in different boiler ash fractions. More volatile isotopes will be partially emitted to the atmosphere via flue gases and fly ash. To our knowledge, there has been no previous study for CFB boiler systems on natural radionuclide enrichment and their atmospheric emissions. Ash samples were collected from Eesti Power Plant's CFB boiler. These samples were processed and analyzed with gamma spectrometry. Activity concentrations (Bq/kg) and enrichment factors were calculated for the (238)U ((238)U, (226)Ra, (210)Pb) and (232)Th ((232)Th, (228)Ra) family radionuclides and for (40)K in different CFB boiler ash fractions. Results from the CFB boiler ash sample analysis showed an increase in the activity concentrations and enrichment factors (up to 4.5) from the furnace toward the electrostatic precipitator block. The volatile radionuclide ((210)Pb and (40)K) activity concentrations in CFB boilers were evenly distributed in finer ash fractions. Activity balance calculations showed discrepancies between input (via oil shale) and output (via ash fractions) activities for some radionuclides ((238)U, (226)Ra, (210)Pb). This refers to a situation where the missing part of the activity (around 20% for these radionuclides) is emitted to the atmosphere. Also different behavior patterns were detected for the two Ra isotopes, (226)Ra and (228)Ra. A part of (226)Ra input activity, unlike (228)Ra, was undetectable in the

  13. INVESTIGATION OF BASALT-RADIONUCLIDE DISTRIBUTION COEFFICIENTS: FISCAL YEAR 1980 ANNUAL REPORT

    SciTech Connect

    Ames, L. L.; McGarrah, J. E.

    1980-12-01

    The Basalt Waste Isolation Project (Rockwell Hanford Operations) is conducting a safety assessment of nuclear waste storage in a repository on the Hanford Site. Pacific Northwest Laboratory, in support of the assessment effort, is generating radionuclide distribution coefficient data between simulated groundwaters and basalts and their secondary mineral products under the range of physicochemical conditions expected in a repository in basalt. Experimental radionuclide distribution coefficients were determined for crushed Pomona, Flow E, and Umtanum basalts at 23°, 60°, 150°, and 300°C at both normal oxygen partial pressure (~0.2 atm) and lower oxygen partial pressure (~10{sup -7} atm), using a static technique. Little or no changes in distribution coefficients were noted for selenium, uranium, technetium, neptunium, or plutonium over the oxygen partial pressure range noted above. Sodium dithionite and hydrazine are now under study as system additives to lower Eh to -0.3 to -0.5 V, the conditions expected to prevail in the closed repository in basalt. Radium, strontium, cesium, and americium are not expected to change oxidation states under repository conditions, while iodine remains an anion in either oxidation state. Lowering the system Eh to the -0.3 to -0.5 V expected in a repository in basalt should result in an oxidation state change and enhanced removal from solution for selenium, uranium, technetium, neptunium, and plutonium. Sorption of iodine was not affected by the Eh changes. Temperature change effects on most radionuclide distribution coefficient (Kd) values over the 23° to 300°C range were major with the exception of iodine and technetium, neither of which were appreciably sorbed at normal to ~10{sup -7} atm oxygen partial pressure. Uranium Kd values increased with an increase in temperature. In addition, uranium Kd values at 23°C decrease by an order of magnitude in response to added CO{sub 3}{sup 2-} in the solution. Cesium basalt Kd values

  14. Description of spatial patterns of radionuclide deposition by lognormal distribution and hot spots.

    PubMed

    Grubich, Andry; Makarevich, V I; Zhukova, O M

    2013-12-01

    Spatial distributions of activity density (kBq/m(2)) and activity concentration (Bq/kg) are studied on sites with non-cultivated soils. Fitting datasets with lognormal, Weibull and normal distributions with sampling size n ≥ 60 showed that radionuclide deposition ((90)Sr, (137)Cs, (238)Pu, (239+240)Pu, (241)Am) due to Chernobyl fallout no more than in 10% of cases are described by Weibull distribution, and in the rest of the cases--by lognormal distribution. However asymptotics of "righthand tail" of empirical (sample) distribution quite often differs from the right-hand tail asymptotics of lognormal distribution. Thereby lognormal distribution is only an approximate statistical model of radionuclides' spatial pattern. Estimates of site surface area with "hot spots" are considered. Also distributions of (137)Cs and (134)Cs activity concentration on the territory contaminated by Fukushima fallout are reviewed. Characteristics of activity concentration for Fukushima and Chernobyl fallouts are collated. The results obtained make it possible to suggest that in both cases spatial contaminations of soil are described by approximately the same statistical models. PMID:24144832

  15. The effect of gravel size fraction on the distribution coefficients of selected radionuclides

    NASA Astrophysics Data System (ADS)

    Um, Wooyong; Serne, R. Jeffrey; Last, George V.; Clayton, Ray E.; Glossbrenner, Ellwood T.

    2009-06-01

    This manuscript addresses the consequences of the common practice of assuming that the gravel fraction of sediments does not participate in sorption reactions and thus sorption quantified by the distribution coefficient ( Kd) construct can be estimated from laboratory tests on sediments less than 2 mm size fraction. However, this common assumption can lead to inaccurate estimates of the mobility and sorption affinity of many radionuclides (e.g., Tc, U, and Np) on gravel dominated sediments at the Hanford Site and other locations. Laboratory batch sorption experiments showed that the distribution coefficients measured using only sediment less than 2 mm size fraction and correcting for inert gravel fraction were not in agreement with those obtained from the bulk sediments including gravel (larger than 2 mm size fraction), depending on the radionuclide. The least reactive radionuclide, Tc had Kd values for bulk sediment with negligible deviations from the inert gravel corrected Kd values measured on less than 2 mm size fraction. However, differences between measured Kd values using sediment less than 2 mm size fraction and the Kd values on the bulk sediment were significant for intermediately and strongly reactive radionuclides such as U and Np, especially on the sediment with gravel fractions that contained highly reactive sites. Highly reactive sites in the gravel fraction were attributed to the presence of Fe oxide coatings and/or reactive fracture faces on the gravel surfaces. Gravel correction factors that use the sum of the Kd, < 2 mm and Kd, > 2 mm values to estimate the Kd for the bulk sediment were found to best describe Kd values for radionuclides on the bulk sediment. Gravel correction factors should not be neglected to predict precisely the sorption capacity of the bulk sediments that contain more than 30% gravel. In addition, more detailed characterization of gravel surfaces should be conducted to identify whether higher reactive sorbents are present in

  16. Assessment of individual radionuclide distributions from the Fukushima nuclear accident covering central-east Japan.

    PubMed

    Kinoshita, Norikazu; Sueki, Keisuke; Sasa, Kimikazu; Kitagawa, Jun-ichi; Ikarashi, Satoshi; Nishimura, Tomohiro; Wong, Ying-Shee; Satou, Yukihiko; Handa, Koji; Takahashi, Tsutomu; Sato, Masanori; Yamagata, Takeyasu

    2011-12-01

    A tremendous amount of radioactivity was discharged because of the damage to cooling systems of nuclear reactors in the Fukushima No. 1 nuclear power plant in March 2011. Fukushima and its adjacent prefectures were contaminated with fission products from the accident. Here, we show a geographical distribution of radioactive iodine, tellurium, and cesium in the surface soils of central-east Japan as determined by gamma-ray spectrometry. Especially in Fukushima prefecture, contaminated area spreads around Iitate and Naka-Dori for all the radionuclides we measured. Distributions of the radionuclides were affected by the physical state of each nuclide as well as geographical features. Considering meteorological conditions, it is concluded that the radioactive material transported on March 15 was the major contributor to contamination in Fukushima prefecture, whereas the radioactive material transported on March 21 was the major source in Ibaraki, Tochigi, Saitama, and Chiba prefectures and in Tokyo. PMID:22084070

  17. Assessment of individual radionuclide distributions from the Fukushima nuclear accident covering central-east Japan

    PubMed Central

    Kinoshita, Norikazu; Sueki, Keisuke; Sasa, Kimikazu; Kitagawa, Jun-ichi; Ikarashi, Satoshi; Nishimura, Tomohiro; Wong, Ying-Shee; Satou, Yukihiko; Handa, Koji; Takahashi, Tsutomu; Sato, Masanori; Yamagata, Takeyasu

    2011-01-01

    A tremendous amount of radioactivity was discharged because of the damage to cooling systems of nuclear reactors in the Fukushima No. 1 nuclear power plant in March 2011. Fukushima and its adjacent prefectures were contaminated with fission products from the accident. Here, we show a geographical distribution of radioactive iodine, tellurium, and cesium in the surface soils of central-east Japan as determined by gamma-ray spectrometry. Especially in Fukushima prefecture, contaminated area spreads around Iitate and Naka-Dori for all the radionuclides we measured. Distributions of the radionuclides were affected by the physical state of each nuclide as well as geographical features. Considering meteorological conditions, it is concluded that the radioactive material transported on March 15 was the major contributor to contamination in Fukushima prefecture, whereas the radioactive material transported on March 21 was the major source in Ibaraki, Tochigi, Saitama, and Chiba prefectures and in Tokyo. PMID:22084070

  18. Investigation of basalt-radionuclide distribution coefficients: fiscal year 1980 annual report

    SciTech Connect

    Ames, L.L.; McGarrah, J.E.

    1980-12-01

    The Basalt Waste Isolation Project (Rockwell Hanford Operations) is conducting a safety assessment of nuclear waste storage in a repository on the Hanford Site. Pacific Northwest Laboratory, in support of the assessment effort, is generating radionuclide distribution coefficient data between simulated groundwaters and basalts and their secondary mineral products under the range of physicochemical conditions expected in a repository in basalt. Experimental radionuclide distribution coefficients were determined for crushed Pomona, Flow E, and Umtanum basalts at 23/sup 0/, 60/sup 0/, 150/sup 0/, and 300/sup 0/C at both normal oxygen partial pressure (approx. 0.2 atm) and lower oxygen partial pressure (approx. 10/sup -7/ atm), using a static technique. Little or no changes in distribution coefficients were noted for selenium, uranium, technetium, neptunium, or plutonium over the oxygen partial pressure range noted above. Sodium dithionite and hydrazine are now under study as system additives to lower Eh to -0.3 to -0.5 V, the conditions expected to prevail in the closed repository in basalt. Temperature change effects on most radionuclide distribution coefficient (Kd) values over the 23/sup 0/ to 300/sup 0/C range were major with the exception of iodine and technetium, neither of which were appreciably sorbed at normal to approx. 10/sup -7/ atm oxygen partial pressure. The effect of radionuclide concentration on the Kd value was shown graphically for cesium and strontium over a range of from 1 x 10/sup -10/ or 10/sup -12/ to 1 x 10/sup -4/M. Initial work was begun on Kd values obtained under controlled Eh and pH conditions to simulate specific oxygen partial pressure and pH conditions expected to occur in the repository environment.

  19. The environmental geochemistry of trace elements and naturally radionuclides in a coal gangue brick-making plant.

    PubMed

    Zhou, Chuncai; Liu, Guijian; Cheng, Siwei; Fang, Ting; Lam, Paul K S

    2014-01-01

    An investigation focused on the transformation and distribution behaviors of trace elements and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace elements were released and redistributed in the brick, fly ash and the flue gas. Elements can be divided into two groups according to their releasing characteristics, high volatile elements (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system. PMID:25164252

  20. The Environmental Geochemistry of Trace Elements and Naturally Radionuclides in a Coal Gangue Brick-Making Plant

    NASA Astrophysics Data System (ADS)

    Zhou, Chuncai; Liu, Guijian; Cheng, Siwei; Fang, Ting; Lam, Paul K. S.

    2014-08-01

    An investigation focused on the transformation and distribution behaviors of trace elements and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace elements were released and redistributed in the brick, fly ash and the flue gas. Elements can be divided into two groups according to their releasing characteristics, high volatile elements (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system.

  1. External exposure doses due to gamma emitting natural radionuclides in some Egyptian building materials.

    PubMed

    Moharram, B M; Suliman, M N; Zahran, N F; Shennawy, S E; El Sayed, A R

    2012-01-01

    Using of building materials containing naturally occurring radionuclides as (238)U, (232)Th and (40)K and their progeny results in an external exposures of the housing of such buildings. In the present study, indoor dose rates for typical Egyptian rooms are calculated using the analytical method and activity concentrations of natural radionuclides in some building materials. Uniform chemical composition of the walls, floor and ceiling as well as uniform mass concentrations of the radionuclides in walls, floor and ceiling assumed. Different room models are assumed to discuss variation of indoor dose rates according to variation in room construction. Activity concentrations of (238)U, (232)Th and (40)K content in eight samples representative Clay soil and different building materials used in most recent Egyptian building were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The specific activity for (238)U, (232)Th and (40)K, from the selected samples, were in the range 14.15-60.64, 2.75-84.66 and 7.35-554.4Bqkg(-1), respectively. The average indoor absorbed dose rates in air ranged from 0.005μGyh(-1) to 0.071μGyh(-1) and the corresponding population-weighted annual effective dose due to external gamma radiation varies from 0.025 to 0.345mSv. An outdoor dose rate for typical building samples in addition to some radiological hazards has been introduced for comparison. PMID:21839645

  2. An assessment of natural radionuclides in water of Langat River estuary, Selangor

    NASA Astrophysics Data System (ADS)

    Hamzah, Zaini; Rosli, Tengku Nurliana Tuan Mohd; Saat, Ahmad; Wood, Ab. Khalik

    2014-02-01

    An estuary is an area that has a free connection with the open sea and it is a dynamic semi-enclosed coastal bodies. Ex-mining, aquaculture and industrial areas in Selangor are the sources of pollutants discharged into the estuary water. Radionuclides are considered as pollutants to the estuary water. Gamma radiations emitted by natural radionuclides through their decaying process may give impact to human. The radiological effect of natural radionuclides which are 226Ra, 228Ra, 40K, 238U and 232Th, were explored by determining the respective activity concentrations in filtered water along the Langat estuary, Selangor. Meanwhile, in- situ water quality parameters such as temperature, dissolve oxygen (DO), salinity, total suspended solid (TSS), pH and turbidity were measured by using YSI portable multi probes meter. The activity concentration of 226Ra, 228Ra and 40K were determined by using gamma-ray spectrometry with high-purity germanium (HPGe) detector. The activity concentrations of 226Ra, 228Ra and 40K in samples are in the range of 0.17 - 0.67 Bq/L, 0.16 - 0.97 Bq/L and 1.22 - 5.57 Bq/L respectively. On the other hand, the concentrations of uranium-238 and thorium-232 were determined by using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). The thorium concentrations are between 0.17 ppm to 0.28 ppm and uranium concentrations were 0.25 ppm to 0.31 ppm. The results show activity concentrations of radionuclides are slightly high near the river estuary. The Radium Equivalent, Absorbed Dose Rate, External Hazard Index, and Annual Effective Dose of 226Ra, 228Ra and 40K are also studied.

  3. An assessment of natural radionuclides in water of Langat River estuary, Selangor

    SciTech Connect

    Hamzah, Zaini Rosli, Tengku Nurliana Tuan Mohd Saat, Ahmad Wood, Ab. Khalik

    2014-02-12

    An estuary is an area that has a free connection with the open sea and it is a dynamic semi-enclosed coastal bodies. Ex-mining, aquaculture and industrial areas in Selangor are the sources of pollutants discharged into the estuary water. Radionuclides are considered as pollutants to the estuary water. Gamma radiations emitted by natural radionuclides through their decaying process may give impact to human. The radiological effect of natural radionuclides which are {sup 226}Ra, {sup 228}Ra, {sup 40}K, {sup 238}U and {sup 232}Th, were explored by determining the respective activity concentrations in filtered water along the Langat estuary, Selangor. Meanwhile, in- situ water quality parameters such as temperature, dissolve oxygen (DO), salinity, total suspended solid (TSS), pH and turbidity were measured by using YSI portable multi probes meter. The activity concentration of {sup 226}Ra, {sup 228}Ra and {sup 40}K were determined by using gamma-ray spectrometry with high-purity germanium (HPGe) detector. The activity concentrations of {sup 226}Ra, {sup 228}Ra and {sup 40}K in samples are in the range of 0.17 - 0.67 Bq/L, 0.16 - 0.97 Bq/L and 1.22 - 5.57 Bq/L respectively. On the other hand, the concentrations of uranium-238 and thorium-232 were determined by using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). The thorium concentrations are between 0.17 ppm to 0.28 ppm and uranium concentrations were 0.25 ppm to 0.31 ppm. The results show activity concentrations of radionuclides are slightly high near the river estuary. The Radium Equivalent, Absorbed Dose Rate, External Hazard Index, and Annual Effective Dose of {sup 226}Ra, {sup 228}Ra and {sup 40}K are also studied.

  4. Distribution of radionuclides in the surface sea water developed by aerial radiological survey

    NASA Astrophysics Data System (ADS)

    Inomata, Yayoi; Aoyama, Michio; Hirose, Katsumi; Sanada, Yukihisa; Torii, Tatsuo; Tsubono, Takaki; Tsumune, Daisuke; Yamada, Masatoshi

    2014-05-01

    This study provides new data analysis method of aerial radiological survey to monitor the distribution of anthropogenic radioactivity in surface seawaters as a first attempt. The aerial radiological survey was performed by the U.S. Department of Energy National Nuclear Security Administration (DOE/NNSA) within a 30 km radius of the Fukushima Daiichi Nuclear Power Plant (FNPP1) on 18 April 2011. We found good correlations between the observed concentrations of FNPP1 derived radionuclides (131I, 134Cs, 137Cs) in the surface seawater and gamma-ray dose rates by aerial radiological surveys (correlation coefficients for 131I, 0.89; 134Cs, 0.96;137Cs, 0.95). The detection limits of 131I, 134Cs, and 137Cs in surface seawaters for the aerial radiological survey are 25, 21, 24 Bq L-1, respectively. Based on these relations, we find that the area with high concentrations of the FNPP1 derived radionuclides spread south-southeast from the FNPP1. The maximum concentrations of 131I, 134Cs, and 137Cs reached 303, 456, and 528 Bq L-1, respectively. The131I/134Cs ratios in surface waters of the high activities area are about 0.6-0.7. Considering the radioactive decay of 131I (half-life: 8.021 d), we confirm that radionuclides in the surface seawater of this area are due to direct release from FNPP1 to the ocean. From these results, it is concluded that the aerial radiological survey is very effective to investigate the accurate distribution of anthropogenic radioactivity in the surface seawater. Furthermore, the model reproduced the distribution pattern of the FNPP1 derived radionuclides in surface seawater obtained by the aerial radiological survey, although simulated results by regional ocean model are underestimated.

  5. Distribution of gamma-ray emitting radionuclides in the environment of Burullus Lake: I. Soils and vegetations.

    PubMed

    El-Reefy, H I; Sharshar, T; Zaghloul, R; Badran, H M

    2006-01-01

    The concentrations and distribution of gamma-ray emitting isotopes in Burullus Lake were investigated with the aim of evaluating the environmental radioactivity. Particularly in wetlands, natural properties of the environment can cause the actual inventory to be different from the activity originally deposited. The mean concentrations of (226)Ra, (232)Th and (40)K were 14.3, 15.5 and 224 Bq/kg, respectively, in the coastal soils. On the other hand, soil samples from the islands had mean concentrations of 13.5, 17.4 and 341 Bq/kg for (226)Ra, (232)Th and (40)K, respectively. Samples from coast and islands show evidence of possible transfer and accumulation of the (137)Cs radionuclide. The mean (137)Cs activity concentrations in the soil samples were 1.2 and 15.1 Bq/kg in the coast and islands, respectively. The vertical migration of (137)Cs was studied based on its content in the consequently located three soil layers down to 30 cm depth. The radium equivalent, dose rate in air and annual dose equivalent from the terrestrial natural gamma-radiation were evaluated. The mean activity concentrations of the gamma-ray emitting radionuclides in vegetation were relatively low. PMID:16427723

  6. Radionuclide migration experiments in a natural fracture in a quarried block of granite

    NASA Astrophysics Data System (ADS)

    Vandergraaf, Tjalle T.; Drew, Douglas J.; Masuda, Sumio

    1996-02-01

    A radionuclide migration experiment was performed over a distance of 1 m in a natural fracture in a quarried block of granite. The fracture in the block was characterized hydraulically by measuring the pressure drop in borehole-to-borehole pump tests. The effective fracture volume in the block was ˜ 100 mL. A silicone coating was applied to the exterior, and the block was immersed in a tank of water to which hydrazine was added to provide a chemically reducing barrier. Migration experiments were performed at a flow rate of 2.2 mL h -1 using 85Sr, 131I, 137Cs, 144Ce, 152Eu, 237Np and 238Pu. A total of 9.5 L of groundwater was pumped through the fracture, corresponding to ˜95 fracture volumes. Only 85Sr, 131I, 137Cs, 237Np and 238Pu were observed in the eluent. Scanning of the fracture surface at the end of the migration experiment showed limited mobility of α-emitting radionuclides and of the rare-earth elements, consistent with static sorption data obtained on representative fracture surface material. The mobility of 137Cs was higher than that of the rare-earth elements, but it was lower than that of 85Sr. When samples of fracture-coating material were separated into fractions with different specific gravity, there was a clear indication of radionuclide association with mineral groups.

  7. Natural and anthropogenic radionuclides in airborne particulate samples collected in Barcelona (Spain).

    PubMed

    Vallés, I; Camacho, A; Ortega, X; Serrano, I; Blázquez, S; Pérez, S

    2009-02-01

    Results for naturally occurring (7)Be, (210)Pb, (40)K, (214)Bi, (214)Pb, (212)Pb, (228)Ac and (208)Tl and anthropogenic (137)Cs in airborne particulate matter in the Barcelona area during the period from January 2001 to December 2005 are presented and discussed. The (212)Pb and (208)Tl, (214)Bi and (214)Pb, (7)Be and (210)Pb radionuclide levels showed a significant correlation with each other, with correlation coefficients of 0.99, 0.78 and 0.69, respectively, suggesting similar origin/behaviour of these radionuclides in the air. Caessium-137 and Potassium-40 were transported to the air as resuspended particle from the soil. The (7)Be and (210)Pb concentrations showed similar seasonal variations, with a tendency for maximum concentrations during the summer months. An inverse relationship was observed between the (7)Be, (210)Pb, (40)K and (137)Cs concentrations and weekly rainfall, indicating washout of atmospheric aerosols carrying these radionuclides. PMID:19027201

  8. Nevada test site radionuclide inventory and distribution program: Report number 4, Areas 18 and 20

    SciTech Connect

    McArthur, R D; Mead, S W

    1988-04-01

    As part of the Radionuclide Inventory and Distribution Program on the Nevada Test Site, in situ measurements of gamma-emitting radionuclides were made at more than 600 locations in six regions near ground zeros in Areas 18 and 20. In addition, several soil samples were collected from each region and analyzed to determine inverse relaxation lengths and radionuclide ratios. Analysis of the data from Area 20 led to estimated inventories of 23 Ci of /sup 241/Am, 30 Ci of /sup 238/Pu, 41 Ci of /sup 239,240/Pu, 18 Ci of /sup 60/Co, 6.4 Ci of /sup 137/Cs, 6.0 Ci of /sup 90/Sr, 17 Ci of /sup 152/Eu, 19 Ci of /sup 154/Eu, and 6.6 Ci of /sup 155/Eu. For Area 18, the estimated inventories were 27 Ci of /sup 241/Am, 4.9 Ci of /sup 238/Pu, 150 Ci of /sup 239,240/Pu, 1.3 Ci of /sup 60/Co, 4.9 Ci of /sup 137/Cs, 13 Ci of /sup 90/Sr, 2.1 Ci of /sup 152/Eu, 1.3 Ci of /sup 154/Eu, and 1.4 Ci of /sup 155/Eu. The locations of the measurements in Area 18 were chosen by importance sampling, which permits the calculation of an estimate of the sampling error. Maps of radionuclide distributions were also generated for all regions except the area near the Palanquin and Cabriolet ground zeros. 3 refs., 65 figs., 7 tabs.

  9. Dispersion of U-series natural radionuclides in stream sediments from Edale, UK.

    PubMed

    Siddeeg, Saifeldin M; Bryan, Nicholas D; Livens, Francis R

    2014-05-01

    The spatial distribution of (238)U-series radionuclides, specifically 238U, 234U, 230Th and 226Ra, has been determined in stream sediments from Edale, Derbyshire, United Kingdom, to explore the behaviour of U-series radionuclides during weathering. For uranium and thorium, two different extraction methods were used, total dissolution with HNO3/HF in a microwave and leaching with aqua regia. This was followed by radiochemical separation using extraction chromatography, then alpha spectrometry measurement. The total radium contents in the sediments were measured using gamma spectrometry, while the leached fraction was measured in the same way as for uranium and thorium. The total sediment content of uranium and thorium ranges from ∼10 up to ∼200 Bq kg(-1), while the radium specific activity lies between ∼15 and 180 Bq kg(-1). In the aqua regia extractions, the uranium and thorium contents are in the range of ∼5 to ∼100 Bq kg(-1), while the radium specific activities are similar to those measured by total dissolution. All the radionuclides show no correlation with organic matter content. The activity ratios 234U/238U, 230Th/238U and 226Ra/238U were used to determine the degree of radioactive disequilibrium. The data show disequilibrium in most of the sediments, with activity ratios of 234U/238U, 230Th/238U and 226Ra/238U>1, inconsistent with evolution through straightforward weathering processes. Multivariate cluster analysis based on five variables, the specific activities of 238U, 234U, 230Th, 226Ra and loss on ignition, was employed to group the data and identify five distinct clusters. There seems to be a link between high radionuclide concentrations and proximity to landslips. PMID:24562972

  10. Enrichment and particle size dependence of polonium and other naturally occurring radionuclides in coal ash.

    PubMed

    Sahu, S K; Tiwari, M; Bhangare, R C; Pandit, G G

    2014-12-01

    Coal fired thermal power contributes 70% of power in India. Coal fired power generation results in huge amounts of fly ash and bottom ash of varying properties. Coal, which contains the naturally occurring radionuclides, on burning results in enrichment of these radionuclides in the ashes. In the present study, coal, bottom ash and fly ash samples collected from six coal-fired power plants in India were measured for (210)Po using alpha spectrometry and for natural U, (226)Ra, (232)Th and (40)K by an HPGe γ-ray spectrometer. (210)Po in fly ash ranged from 25.7 to 70 Bq/kg with a mean value of 40.5 Bq/kg. The range and mean activities of (238)U, (226)Ra, (232)Th, (40)K in fly ash were 38.5-101 (78.1), 60-105.7 (79), 20-125 (61.7) and 43.6-200 (100) Bq/kg respectively. Fly ash and bottom ash contains two to five times more natural radionuclides than feed coal. The results were compared with the available data from earlier studies in other countries. The effect of particle size on enrichment factor of the nuclides in fly ash was studied. (210)Po showed the largest size dependence with its concentration favoring the smaller particle size while (232)Th showed least size dependence. (238)U and (226)Ra showed behavior intermediate to that of (210)Po and (232)Th. Also the correlation between sulfur content of the feed coal and activity of (210)Po was investigated. Increased sulfur content in feed coal enhanced enrichment of (210)Po in ash. PMID:24813148

  11. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    SciTech Connect

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-21

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely {sup 40}K, {sup 232}Th and {sup 238}U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  12. The Distributed Nature of Pattern Generalization

    ERIC Educational Resources Information Center

    Rivera, Ferdinand

    2015-01-01

    Drawing on a review of recent work conducted in the area of pattern generalization (PG), this paper makes a case for a distributed view of PG, which basically situates processing ability in terms of convergences among several different factors that influence PG. Consequently, the distributed nature leads to different types of PG that depend on the…

  13. Natural attenuation of metals and radionuclides -- An overview of the Sandia/DOE approach

    SciTech Connect

    Waters, R.D.; Brady, P.V.; Borns, D.J.

    1998-02-01

    Sandia National Laboratories is developing guidelines that outline the technical basis for relying on natural attenuation for the remediation of metals and radionuclide-contaminated soils and groundwaters at US Department of Energy (DOE) sites for those specific cases where natural processes are effective at ameliorating soil and groundwater toxicity. Remediation by monitored natural attenuation (MNA) requires a clear identification of the specific reaction(s) by which contaminant levels are made less available as well as considerable long-term monitoring. Central to MNA is the development of a conceptual model describing the biogeochemical behavior of contaminant(s) in the subsurface. The conceptual model will be used to make testable predictions of contaminant availability over time. In many cases, comparison between this prediction and field measurements will provide the test of whether MNA is to be implemented. As a result, development of the conceptual model should guide site characterization activities as well as long-term monitoring.

  14. Statistical analysis of the spatial distribution of radionuclides in soils around a coal-fired power plant in Spain.

    PubMed

    Charro, Elena; Pardo, Rafael; Peña, Víctor

    2013-10-01

    Coal-fired power-plants (CFPP) can be a source of contamination because the coal contains trace amounts of natural radionuclides, such as (40)K and (238)U, (232)Th and their decay products. These radionuclides can be released as fly ash from the CFPP and deposited from the atmosphere on the nearby top soils, therefore modifying the natural radioactivity background levels, and subsequently increasing the total radioactive dose received for the nearby population. In this paper, an area of 64 km(2) around the CFPP of Velilla del Río Carrión (Spain) has been studied by collecting 67 surface soil samples and measuring the activities of one artificial and six natural radionuclides by gamma spectrometry. The found results are similar to the background natural levels and ranged from 0 to 209 for (137)Cs, 11 to 50 for (238)U, 14 to 67 for (226)Ra, 29 to 380 for (210)Pb, 15 to 68 for (232)Th, 17 to 78 for (224)Ra, 97 to 790 for (40)K (all values in Bq kg(-1)). Besides the classical radiochemical tools, Analysis of Variance (ANOVA), Principal Component Analysis (PCA), Hierarchical Clustering Analysis (HCA), and kriging mapping have been used to the experimental dataset, allowing us to find the existence of two different models of spatial distribution around the CFPP. The first, followed by (238)U, (226)Ra, (232)Th, (224)Ra and (40)K can be assigned to 'natural background radioactivity', whereas the second model, followed by (210)Pb and (137)Cs, is based on 'atmospheric fallout radioactivity'. The main conclusion of this work is that CFPP has not influence on the radioactivity levels measured in the studied area, with has a mean annual outdoor effective dose E = 71 ± 22 μSv, very close to the average UNSCEAR value of 70 μSv, thus confirming the almost non-existent radioactive risk posed by the presence of the CFPP. PMID:23680923

  15. Natural-analog studies for partial validation of conceptual models of radionuclide retardation at the Waste Isolation Pilot Plant (WIPP)

    SciTech Connect

    Ward, D.B.; Brookins, D.G. . Dept. of Geology); Siegel, M.D.; Lambert, S.J. )

    1990-01-01

    Transport by groundwater within the Culebra Dolomite, an aquifer above the Waste Isolation Pilot Plant (WIPP), is the most probable mechanism for long-term release of radionuclides to the accessible environment. Radionuclides could be retarded by sorption if the groundwater is exposed to sufficient amounts of fracture-lining clays. In this natural-analog study, distributions of U and trace metals have been examined to constrain the strength of clay/solute interactions within the Culebra. Uranium solid/liquid distribution ratios, calculated from U concentrations of groundwaters and consanguineous fracture-filling clays, range from {approximately}80 to 800 m{ell}/g and imply retardation factors of 60 to 500 using a fracture-flow model. Retardation factors inferred from uranium-series disequilibria and {sup 14}C ages in Culebra groundwaters alone are much lower ({approximately}10), implying that clays may contain a significant unreactive component of U. Such a possibility is corroborated by Rb/Sr ages; these imply long-term stability of the clays,with resetting occurring more than 250 Ma ago. Factor analysis and mass-balance calculations suggest, however, that Mg-rich clays are dissolving in Pleistocene-age groundwaters and/or are converting to Na-rich smectites, and that B and Li are taken up from the water by the clays. Apparently, the solution chemistry reflects gradual equilibration of clays with groundwater, but thus far the bulk of the clays remain structurally intact. Measurements of the distribution of U in the Culebra will be more meaningful if the inert and exchangeable components of the U content of the clays can be quantified. 26 refs., 3 figs., 2 tabs.

  16. Distribution of radionuclides in an iron calibration standard for a free release measurement facility.

    PubMed

    Hult, Mikael; Stroh, Heiko; Marissens, Gerd; Tzika, Faidra; Lutter, Guillaume; Šurán, Jiri; Kovar, Petr; Skala, Lukas; Sud, Jaromír

    2016-03-01

    A Europallet-sized calibration standard composed of 12 grey cast iron tubes contaminated with (60)Co and (110m)Ag with a mass of 246kg was developed. As the tubes were produced through centrifugal casting it was of particular concern to study the distribution of radionuclides in the radial direction of the tubes. This was done by removing 72 small samples (swarf) of ~0.3g each on both the inside and outside of the tubes. All of the samples were measured in the underground laboratory HADES. PMID:26597655

  17. Natural and artificial radionuclide activity concentrations in surface sediments of Izmit Bay, Turkey.

    PubMed

    Ergül, Halim Aytekin; Belivermiş, Murat; Kılıç, Önder; Topcuoğlu, Sayhan; Çotuk, Yavuz

    2013-12-01

    Surface sediments from the north-eastern coast of the Marmara Sea, Turkey's most industrialized coastal region, were enriched with radioisotopes from the Chernobyl explosion in 1986. Caesium-137 in these sediments is also thought to originate from one former paper mill located nearby that used wood contaminated by Chernobyl explosion-originated (137)Cs for paper production. The average activity concentration of the (137)Cs was 21 Bq kg(-1), while naturally occurring radioisotopes, i.e. (40)K, (226)Ra, and (228)Ra, were 568, 18 and 24 Bq kg(-1), respectively, in surface sediments. The natural radionuclide activities reached their highest levels near petrochemical, phosphate and fertilizer processing facilities. Average (137)Cs activities were generally up to ten times higher than in Middle Eastern marine sediments and lower than those in Northern European sediments. PMID:23981563

  18. Radionuclide adsorption distribution coefficients measured in Hanford sediments for the low level waste performance assessment project

    SciTech Connect

    Kaplan, D.I.; Serne, R.J.; Owen, A.T.

    1996-08-01

    Preliminary modeling efforts for the Hanford Site`s Low Level Waste-Performance Assessment (LLW PA) identified {sup 129}I, {sup 237}Np, {sup 79}Se, {sup 99}Tc, and {sup 234},{sup 235},{sup 238}U as posing the greatest potential health hazard. It was also determined that the outcome of these simulations was very sensitive to the parameter describing the extent to which radionuclides sorb to the subsurface matrix, i.e., the distribution coefficient (K{sub d}). The distribution coefficient is a ratio of the radionuclide concentration associated with the solid phase to that in the liquid phase. The objectives of this study were to (1) measure iodine, neptunium, technetium, and uranium K{sub d} values using laboratory conditions similar to those expected at the LLW PA disposal site, and (2) evaluate the effect of selected environmental parameters, such as pH, ionic strength, moisture concentration, and radio nuclide concentration, on K{sub d} values of selected radionuclides. It is the intent of these studies to develop technically defensible K{sub d} values for the PA. The approach taken throughout these studies was to measure the key radio nuclide K{sub d} values as a function of several environmental parameters likely to affect their values. Such an approach provides technical defensibility by identifying the mechanisms responsible for trends in K{sub d} values. Additionally, such studies provide valuable guidance regarding the range of K{sub d} values likely to be encountered in the proposed disposal site.

  19. Correlations of natural radionuclides in soil with those in sediment from the Danube and nearby irrigation channels.

    PubMed

    Krmar, M; Varga, E; Slivka, J

    2013-03-01

    The correlation between activity concentrations of some natural radionuclides ((238)U, (226)Ra, (232)Th, (40)K) measured in soil and in sediment taken from the Danube River and nearby irrigation channels was studied. The soil samples were collected from the northern part of Serbia and the sediment from the Serbian part of the Danube River and from the surrounding irrigation channels. The correlation between (238)U and other natural radionuclides in irrigation channel sediments was not as good as in the Danube. One of the possible explanations for this weak correlation can be the different chemical dynamics of (238)U in the irrigation channel sediment or changes of the (238)U activity concentration in irrigation channel sediment due to some human activities. The evaluation of ratios of activity concentrations of some natural radionuclides could be a more sensitive method for the determination of contaminant, rather than the straightforward analysis of activity concentrations. PMID:22244685

  20. Evaluation of natural radionuclides at Um-Greifat area, eastern desert of Egypt.

    PubMed

    Nada, A

    2003-02-01

    Air borne radiometric maps and remote sensing techniques were used to explore for the occurrence of radioactive materials. The previous techniques recorded radioactive mineralization for the first time along the NW-SE trending fault zones within the Miocene clastic-carbonate sediments. In the present study, gamma-ray spectrometry was used to confirm the presence of this mineralization. Concentrations of radionuclides, associated within the iron ochre at Um-Greifat area, have been measured, using a hyper-pure germanium spectrometer. The variation in concentration of radionuclides for the area under investigation can be classified into A, B and C regions of high, medium and low natural radioactivity. In region A, average concentration in Bqkg(-1) has been observed to range from 1858 to 4062 for 238U, between 29 and 151 for 232Th, from 60 to 136 for 235U and between 46 and 409 Bqkg(-1) for 40K. Radium equivalent activities (Ra(eq)) in addition to external and internal hazard indices (H(ex), H(in)) have also been determined. Ra(eq) varies between 1901 and 4307Bqkg(-1), which exceeds the permitted value (370Bqkg(-1)) and H(ex) and H(in) are higher than 1. The high activity concentration within region A points to an environmental hazard, while regions B and C have less exposure effect on human beings. PMID:12573328

  1. Ecological distribution and bioavailability of uranium series radionuclides in terrestrial food chains: Key Lake uranium operations, northern Saskatchewan

    SciTech Connect

    Thomas, P.A.

    1997-12-31

    The purpose of this study was to determine radionuclide uptake within the terrestrial ecosystem at uranium mining operations in northern Saskatchewan. The study site was the Key Lake mine, chosen because it has been an operational mine, mill, and surface tailings area for 15 years and will continue to be an active ore-milling and tailings disposal area for the next 40 years. The focus of the study was on the small mammal food chains in black spruce bogs nearest to the Key Lake facilities, since bog habitats tend to absorb and accumulate radionuclides. Three study sites were chosen on the basis of their proximity to sources of radioactive dust and the presence of bog habitats. Interconnected terrestrial ecosystem components were sampled at the same time at each site. Samples of needles, twigs, ground cover, litter, soils, small mammals, and birds were analyzed for the four radionuclides of greatest concern in the uranium decay series. Radiation doses were calculated to small mammals and birds, food chain transfer parameters were determined to enable future modelling of environmental pathways, and a variety of atmospheric dust collectors were pilot tested to examine the rates of radionuclide deposition from facility emissions to local environments. Four sets of conclusions are discussed regarding: radionuclide distribution within habitats and among sites; the radionuclides responsible for animal doses; the relative bioavailability of radionuclides among sites; and the measurement of atmospheric deposition rates.

  2. Distributed and Relative Nature of Professional Expertise

    ERIC Educational Resources Information Center

    Pillay, Hitendra; McCrindle, Andrea R.

    2005-01-01

    This exploratory study investigates the distributed nature and complexity of professional expertise by examining the patterns of cognitive processes in novices and experts who are using ultrasound technology to make diagnoses. The study aims to identify and provide an explanation for such patterns in light of the recent debate on the locus of…

  3. Natural and artificial radionuclide measurements and radioactivity assessment of soil samples in eastern Sichuan province (China).

    PubMed

    Wang, Zhonghai; He, Jun; Du, Yu; He, Yang; Li, Zhiqian; Chen, Zhihua; Yang, Chaowen

    2012-07-01

    The activity concentrations of natural and artificial radionuclides were measured in the eastern region of Sichuan province (China). One hundred and ninety-three soil samples from this region were collected and analysed by high-purity germanium gamma spectrometry. The measured results show that the average radioactivity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs in the soil samples are 26, 49, 440 and 6 Bq kg(-1), respectively. The calculated average radium equivalent activity is 130 Bq kg(-1), which is less than the recommended limit of 370 Bq kg(-1). The absorbed dose rate and annual effective dose are 60 nGy h(-1) and 74 µSv, respectively. This is the first time the absorbed dose rate in the east region of Sichuan has been mapped. Overall, the environmental radiation background is greater in the southern part of the area studied than in the northern. PMID:22128351

  4. Measurement of natural radionuclides in Malaysian bottled mineral water and consequent health risk estimation

    NASA Astrophysics Data System (ADS)

    Priharti, W.; Samat, S. B.; Yasir, M. S.

    2015-09-01

    The radionuclides of 226Ra, 232Th and 40K were measured in ten mineral water samples, of which from the radioactivity obtained, the ingestion doses for infants, children and adults were calculated and the cancer risk for the adult was estimated. Results showed that the calculated ingestion doses for the three age categories are much lower than the average worldwide ingestion exposure of 0.29 mSv/y and the estimated cancer risk is much lower than the cancer risk of 8.40 × 10-3 (estimated from the total natural radiation dose of 2.40 mSv/y). The present study concludes that the bottled mineral water produced in Malaysia is safe for daily human consumption.

  5. Measurement of natural radionuclides in Malaysian bottled mineral water and consequent health risk estimation

    SciTech Connect

    Priharti, W.; Samat, S. B.; Yasir, M. S.

    2015-09-25

    The radionuclides of {sup 226}Ra, {sup 232}Th and {sup 40}K were measured in ten mineral water samples, of which from the radioactivity obtained, the ingestion doses for infants, children and adults were calculated and the cancer risk for the adult was estimated. Results showed that the calculated ingestion doses for the three age categories are much lower than the average worldwide ingestion exposure of 0.29 mSv/y and the estimated cancer risk is much lower than the cancer risk of 8.40 × 10{sup −3} (estimated from the total natural radiation dose of 2.40 mSv/y). The present study concludes that the bottled mineral water produced in Malaysia is safe for daily human consumption.

  6. Natural radionuclide and radiological assessment of building materials in high background radiation areas of Ramsar, Iran

    PubMed Central

    Bavarnegin, Elham; Moghaddam, Masoud Vahabi; Fathabadi, Nasrin

    2013-01-01

    Building materials, collected from different sites in Ramsar, a northern coastal city in Iran, were analyzed for their natural radionuclide contents. The measurements were carried out using a high resolution high purity Germanium (HPGe) gamma-ray spectrometer system. The activity concentration of 226Ra, 232Th, and 40K content varied from below the minimum detection limit up to 86,400 Bqkg-1, 187 Bqkg-1, and 1350 Bqkg-1, respectively. The radiological hazards incurred from the use of these building materials were estimated through various radiation hazard indices. The result of this survey shows that values obtained for some samples are more than the internationally accepted maximum limits and as such, the use of them as a building material pose significant radiation hazard to individuals. PMID:23776313

  7. Activity concentration and spatial distribution of radionuclides in marine sediments close to the estuary of Shatt al-Arab/Arvand Rud River, the Gulf.

    PubMed

    Patiris, D L; Tsabaris, C; Anagnostou, C L; Androulakaki, E G; Pappa, F K; Eleftheriou, G; Sgouros, G

    2016-06-01

    Tigris and Euphrates rivers both emerge in eastern Turkey and cross Syria and Iraq. They unite to Shatt al-Arab/Arvand Rud River and discharge in Arabic/Persian Gulf. The activity concentration of natural and anthropogenic radionuclides was measured during the August of 2011 in a number of surficial sediment samples collected from the seabed along an almost straight line beginning near the estuary mouth and extending seaward. The results exhibited low activity concentration levels and an almost homogeneous spatial distribution except locations where sediment of biogenic origin, poor in radionuclides, dilute their concentrations. Dose rates absorbed by reference marine biota were calculated by the ERICA Assessment Tool considering the contribution of 40 K. The results revealed a relatively low impact of 40 K mainly to species living in, on and close to the seabed. Also, statistical association of radionuclides with selected stable elements (Ca, Ba and Sr) did not indicate presence of by-products related with oil and gas exploitation and transportation activities. Moreover, a semi-empirical sedimentology model applied to reproduce seabed granulometric facies based entirely on radionuclides activity concentrations. PMID:26945883

  8. Radiological impact of dietary intakes of naturally occurring radionuclides on Pakistani adults.

    PubMed

    Akhter, P; Rahman, K; Orfi, S D; Ahmad, N

    2007-02-01

    Daily dietary intakes of three naturally occurring long-lived radionuclides (232)Th, (238)U and (40)K were estimated for the adult population of Pakistan using neutron activation analysis (NAA), inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), respectively. The daily intakes of (232)Th ranged from 4 to 29 mBq, (238)U ranged from 17 to 82 mBq and (40)K ranged from 51 to 128 Bq. The geometric means of these intakes were 10 mBqd(-1) for (232)Th, 33 mBqd(-1) for (238)U and 78.5 Bqd(-1) for (40)K. The measured values give annual committed effective doses of 0.80, 0.53 and 178.75 microSvyr(-1) for (232)Th, (238)U and (40)K, respectively to Pakistani population. The net radiological impact of these radionuclides is 180.08 microSvyr(-1). This value gives cancer risk factor of 4.5 x 10(-4) and loss of life expectancy of 0.87 days only. Whereas ICRP cancer risk factor for general public is 2.5 x 10(-3) and total risk involve from the all natural radiation sources based on global average annual radiation dose of 2.4 mSvyr(-1) is 6.0 x 10(-3). The estimated cancer risk shows that probability of increase of cancer risk from daily Pakistani diet is only a minor fraction of ICRP values. Therefore, the diet does not pose any significant health hazard and is considered radiologically safe for human consumption. PMID:17034921

  9. Distribution and surface enrichment of radionuclides in lead-bismuth eutectic from spallation targets

    NASA Astrophysics Data System (ADS)

    Hammer-Rotzler, Bernadette; Neuhausen, Jörg; Boutellier, Viktor; Wohlmuther, Michael; Zanini, L.; David, J.-C.; Türler, Andreas; Schumann, Dorothea

    2016-07-01

    With the development of new high-power neutron spallation sources --both for scientific application and as neutron production tool for accelerator-driven systems-- the demand for experimentally obtained nuclear data on the residue nuclei production in the target is constantly increasing. In the present work, we examined two lead-bismuth-eutectic targets, irradiated with high-energy protons, concerning their radionuclide content and the spatial distribution of selected isotopes. The first one was the so-called ISOLDE target, being irradiated with 1-1.4GeV protons at CERN-ISOLDE, the second one was the MEGAPIE target, irradiated at PSI with 590MeV protons. In particular, we investigated the phenomenon of radionuclide enrichment on free surfaces in both targets. It turned out that considerable accumulation can be found especially in the case of lanthanides. The depletion process is enhanced at increased temperatures. The results are compared with theoretical predictions; some possible consequences of the findings are illustrated.

  10. Uranium and other natural radionuclides in the sediments of a Mediterranean fjord-like embayment, Amvrakikos Gulf (Ionian Sea), Greece.

    PubMed

    Papaefthymiou, H; Athanasopoulos, D; Papatheodorou, G; Iatrou, M; Geraga, M; Christodoulou, D; Kordella, S; Fakiris, E; Tsikouras, B

    2013-08-01

    The distribution of the natural radionuclides ((238)U, (232)Th, (226)Ra, (40)K) and the artificial (137)Cs was studied in sediment cores collected from Amvrakikos Gulf, a seasonal anoxic marine basin, using γ-ray spectrometry. The activity of radionuclides, along with the concentrations of Fe and Mn, were also studied in relation to the total organic carbon and the granulometric fractions of the sediments. The results obtained revealed higher (238)U activity concentrations in all the examined sediment samples compared to the world and Greek average values for soil. The high activity values of (238)U are attributed, besides the lattice-held fraction, to phosphate fertilizer inputs in the Gulf via major rivers and/or to alteration processes of phosphate ores located mainly in the drainage basin of the river Louros. The elevated activity values of (40)K could be attributed to the mineralogical composition of the sediments and to phosphate fertilizers containing potassium. Organic matter seems to be a more efficient sorbent for U than clay minerals and amorphous Fe and Mn-oxyhydroxides. Scanning electron microscopy, together with qualitative analysis of some smectites, reveals the occurrence of U, suggesting a limited absorption of U onto clay minerals. The applied BCR sequential extraction procedure revealed that U was found mainly in the refractory phase or associated with organic matter and to a lesser extent as surface-coating oxides, with the exception of one sediment core which is characterized by high content of fresh marine organic matter and presents high percentage of U in the exchangeable fraction. PMID:23538023

  11. Assessments of radioactivity concentration of natural radionuclides and radiological hazard indices in sediment samples from the East coast of Tamilnadu, India with statistical approach.

    PubMed

    Ravisankar, R; Chandramohan, J; Chandrasekaran, A; Prince Prakash Jebakumar, J; Vijayalakshmi, I; Vijayagopal, P; Venkatraman, B

    2015-08-15

    This paper reports on the distribution of three natural radionuclides (238)U, (232)Th and (40)K in coastal sediments from Pattipulam to Devanampattinam along the East coast of Tamilnadu to establish baseline data for future environmental monitoring. Sediment samples were collected by a Peterson grab samples from 10m water depth parallel to the shore line. Concentration of natural radionuclides were determined using a NaI(Tl) detector based γ-spectrometry. The mean activity concentration is ⩽2.21, 14.29 and 360.23Bqkg(-1) for (238)U, (232)Th and (40)K, respectively. The average activity of (232)Th, (238)U and (40)K is lower when compared to the world average value. Radiological hazard parameters were estimated based on the activity concentrations of (238)U, (232)Th and (40)K to find out any radiation hazard associated with the sediments. The radiological hazard parameters such as radium equivalent activity (Raeq), absorbed gamma dose rates in air (DR), the annual gonadal dose equivalent (AGDE), annual effective dose equivalent (AEDE), external hazard index (Hex) internal hazard index (Hin), activity utilization index (AUI) and excess lifetime cancer (ELCR) associated with the radionuclides were calculated and compared with internationally approved values and the recommended safety limits. Pearson correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied in order to recognize and classify radiological parameters in sediments collected at 22 sites on East coast of Tamilnadu. The values of radiation hazard parameters were comparable to the world averages and below the recommended values. Therefore, coastal sediments do not to pose any significant radiological health risk to the people living in nearby areas along East coast of Tamilnadu. The data obtained in this study will serve as a baseline data in natural radionuclide concentration in sediments along the coastal East coast of Tamilnadu. PMID:26036177

  12. Study on vertical distribution of radionuclides (40K, Th and U) in soil collected from Manjung district

    NASA Astrophysics Data System (ADS)

    Zainal, Fetri; Hamzah, Zaini; Saat, Ahmad; Wood, Khalik; Alias, Masitah

    2016-01-01

    The accumulation of radionuclides in soil is a greatest concerns due to their toxicity. This study investigated the vertical distribution of radionuclides and radiological assessment in a soil profile were collected in three different directions [North (N), North-East (NE) and South-East (SE)] within 40 km from Manjung district. All profile samples were collected down to 45cm at 7.5cm interval using hand auger. Soil density and radionuclides (40K, Th and U) concentrations were determined by gravimetric method and Energy Dispersive X-Ray Fluorescence (EDXRF) technique, respectively. The radionuclides concentrations was in decreasing order of 40K > Th > U. Soil quality assessment was carried out using Enrichment Factor (EF), Pollution Index (PI) and Geoaccumulation Index (I geo) where all radionuclides show significant enrichment (5 < EF < 20), PI classified as middle pollution classes and 0 < Igeo < 1, indicating moderately polluted, respectively. From the concentration of radionuclides, the radiological risk was calculated and the present result show external hazard index (Hex) is below than unity indicate low radiological risk.

  13. Distribution of radionuclides and water in Bandelier Tuff beneath a former Los Alamos liquid waste disposal site after 33 years

    SciTech Connect

    Nyhan, J.W.; Drennon, B.J.; Abeele, W.V.; Trujillo, G.; Herrera, W.J.; Wheeler, M.L.; Booth, J.W.; Purtymun, W.D.

    1984-07-01

    The distribution of radionuclides and water in Bandelier Tuff beneath a former liquid waste disposal site at Los Alamos was investigated. The waste use history of the site was described, as well as several pertinent laboratory and field studies of water and radionuclide migration in Bandelier Tuff. The distribution of plutonium, /sup 241/Am, and water was determined in a set of about 800 tuff samples collected to sampling depths of 30 m beneath two absorption beds. These data were then related to site geohydrologic data. Water and radionuclide concentrations found after 33 years were compared with the results of similar studies previously performed at this site, and the implications of these comparisons are discussed relative to nuclear waste management. 19 references, 6 figures, 4 tables.

  14. Doses of external exposure in Jordan house due to gamma-emitting natural radionuclides in building materials.

    PubMed

    Al-Jundi, J; Ulanovsky, A; Pröhl, G

    2009-10-01

    The use of building materials containing naturally occurring radionuclides as (40)K, (232)Th, and (238)U and their progeny results in external exposures of the residents of such buildings. In the present study, indoor dose rates for a typical Jordan concrete room are calculated using Monte Carlo method. Uniform chemical composition of the walls, floor and ceiling as well as uniform mass concentrations of the radionuclides in walls, floor and ceiling are assumed. Using activity concentrations of natural radionuclides typical for the Jordan houses and assuming them to be in secular equilibrium with their progeny, the maximum annual effective doses are estimated to be 0.16, 0.12 and 0.22 mSv a(-1) for (40)K, (232)Th- and (238)U-series, respectively. In a total, the maximum annual effective indoor dose due to external gamma-radiation is 0.50 mSv a(-1). Additionally, organ dose coefficients are calculated for all organs considered in ICRP Publication 74. Breast, skin and eye lenses have the maximum equivalent dose rate values due to indoor exposures caused by the natural radionuclides, while equivalent dose rates for uterus, colon (LLI) and small intestine are found to be the smallest. More specifically, organ dose rates (nSv a(-1)per Bq kg(-1)) vary from 0.044 to 0.060 for (40)K, from 0.44 to 0.60 for radionuclides from (238)U-series and from 0.60 to 0.81 for radionuclides from (232)Th-series. The obtained organ and effective dose conversion coefficients can be conveniently used in practical dose assessment tasks for the rooms of similar geometry and varying activity concentrations and local-specific occupancy factors. PMID:19628312

  15. Utilization of natural hematite as reactive barrier for immobilization of radionuclides from radioactive liquid waste.

    PubMed

    El Afifi, E M; Attallah, M F; Borai, E H

    2016-01-01

    Potential utilization of hematite as a natural material for immobilization of long-lived radionuclides from radioactive liquid waste was investigated. Hematite ore has been characterized by different analytical tools such as Fourier transformer infrared (FTIR), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal (DT) analysis, scanning electron microscopy (SEM) and BET-surface area. In this study, europium was used as REEs(III) and as a homolog of Am(III)-isotopes (such as (241)Am of 432.6 y, (242m)Am of 141 y and (243)Am of 7370 y). Micro particles of the hematite ore were used for treatment of radioactive waste containing (152+154)Eu(III). The results indicated that 96% (4.1 × 10(4) Bq) of (152+154)Eu(III) was efficiently retained onto hematite ore. Kinetic experiments indicated that the processes could be simulated by a pseudo-second-order model and suggested that the process may be chemisorption in nature. The applicability of Langmuir, Freundlich and Temkin models was investigated. It was found that Langmuir isotherm exhibited the best fit with the experimental results. It can be concluded that hematite is an economic and efficient reactive barrier for immobilization of long-lived radio isotopes of actinides and REEs(III). PMID:26465672

  16. Radiation dose to Malaysian infants from natural radionuclides via consumption of powdered milk

    SciTech Connect

    Uwatse, Onosohwo Bemigho; Olatunji, Michael Adekunle; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd.

    2015-04-24

    Milk is the basic food stuff for the infants because they generally consume more milk on a daily basis as its minerals and proteins are essential for their growth and development, therefore, it is very important to assess the natural radioactivity levels and the associated dose in the widely consumed powered infant’s milk. As a result, 14 brands of infant’s powdered milk were collected from different supermarkets around Selangor, Malaysia and analysed for {sup 226}Ra, {sup 232}Th and {sup 40}K activities. The obtained mean activity of {sup 226}Ra, {sup 232}Th and {sup 40}K are 3.05±1.84, 2.55±2.48 and 99.1±69.5 Bqkg{sup −1}, respectively. Among the analysed milk samples, the brand from Philippines (Lactogen) showed low level of radioactivity while Singaporean brand (S26 SMA Gold) showed the highest. The estimated mean annual effective doses due to the ingestion of natural radionuclides in the sampled milk are 635 and 111 µSv for infant ≤ 1y and infant 1-2y, respectively. The obtained dose value does not yet pose any significant radiological hazards to the population under investigation comparing with the 1.0 mSvy{sup −1} recommended by ICRP for all ages.

  17. Radiation dose to Malaysian infants from natural radionuclides via consumption of powdered milk

    NASA Astrophysics Data System (ADS)

    Uwatse, Onosohwo Bemigho; Olatunji, Michael Adekunle; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd.

    2015-04-01

    Milk is the basic food stuff for the infants because they generally consume more milk on a daily basis as its minerals and proteins are essential for their growth and development, therefore, it is very important to assess the natural radioactivity levels and the associated dose in the widely consumed powered infant's milk. As a result, 14 brands of infant's powdered milk were collected from different supermarkets around Selangor, Malaysia and analysed for 226Ra, 232Th and 40K activities. The obtained mean activity of 226Ra, 232Th and 40K are 3.05±1.84, 2.55±2.48 and 99.1±69.5 Bqkg-1, respectively. Among the analysed milk samples, the brand from Philippines (Lactogen) showed low level of radioactivity while Singaporean brand (S26 SMA Gold) showed the highest. The estimated mean annual effective doses due to the ingestion of natural radionuclides in the sampled milk are 635 and 111 µSv for infant ≤ 1y and infant 1-2y, respectively. The obtained dose value does not yet pose any significant radiological hazards to the population under investigation comparing with the 1.0 mSvy-1 recommended by ICRP for all ages.

  18. 3D dose and TCP distribution for radionuclide therapy in nuclear medicine

    SciTech Connect

    Valente, M.; Malano, F.; Perez, P.

    2010-08-04

    A common feature to any radiant therapy is that lesion and health tissue dosimetry provides relevant information for treatment optimization along with dose-efficacy and dose-complication correlation studies. Nowadays, different radionuclide therapies are commonly available, assessing both systemic and loco-regional approach and using different alfa-, beta-and gamma-emitting isotopes and binding molecules. It is well established, that specific dosimetric approaches become necessary according to each therapy modality. Sometimes, observed activity distribution can be satisfactory represented by simple geometrical models. However, Monte Carlo techniques are capable of better approaches, therefore becoming sometimes the only way to get dosimetric data since the patient-specific situation can not be adequately represented by conventional dosimetry techniques. Therefore, due to strong limitations of traditional and standard methods, this work concentrates on the development of a dedicated and novel calculation system in order to assess the dose distribution within the irradiated patient. However, physical dose may not be enough information in order to establish real deterministic biological/metabolic effects; therefore complementary radiobiological models have been suitably introduced with the aim of performing realistic 3D dose as well as corresponding Tumor Control Probability distribution calculation.

  19. 3D dose and TCP distribution for radionuclide therapy in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Valente, M.; Malano, F.; Pérez, P.

    2010-08-01

    A common feature to any radiant therapy is that lesion and health tissue dosimetry provides relevant information for treatment optimization along with dose-efficacy and dose-complication correlation studies. Nowadays, different radionuclide therapies are commonly available, assessing both systemic and loco-regional approach and using different alfa-, beta-and gamma-emitting isotopes and binding molecules. It is well established, that specific dosimetric approaches become necessary according to each therapy modality. Sometimes, observed activity distribution can be satisfactory represented by simple geometrical models. However, Monte Carlo techniques are capable of better approaches, therefore becoming sometimes the only way to get dosimetric data since the patient-specific situation can not be adequately represented by conventional dosimetry techniques. Therefore, due to strong limitations of traditional and standard methods, this work concentrates on the development of a dedicated and novel calculation system in order to assess the dose distribution within the irradiated patient. However, physical dose may not be enough information in order to establish real deterministic biological/metabolic effects; therefore complementary radiobiological models have been suitably introduced with the aim of performing realistic 3D dose as well as corresponding Tumor Control Probability distribution calculation.

  20. Genotoxic endpoints in the earthworms sub-lethal assay to evaluate natural soils contaminated by metals and radionuclides.

    PubMed

    Lourenço, Joana I; Pereira, Ruth O; Silva, Ana C; Morgado, José M; Carvalho, Fernando P; Oliveira, João M; Malta, Margarida P; Paiva, Artur A; Mendo, Sónia A; Gonçalves, Fernando J

    2011-02-15

    Eisenia andrei was exposed, for 56 days, to a contaminated soil from an abandoned uranium mine and to the natural reference soil LUFA 2.2. The organisms were sampled after 0, 1, 2, 7, 14 and 56 days of exposure, to assess metals bioaccumulation, coelomocytes DNA integrity and cytotoxicity. Radionuclides bioaccumulation and growth were also determined at 0 h, 14 and 56 days of exposure. Results have shown the bioaccumulation of metals and radionuclides, as well as, growth reduction, DNA damages and cytotoxicity in earthworms exposed to contaminated soil. The usefulness of the comet assay and flow cytometry, to evaluate the toxicity of contaminants such as metals and radionuclides in earthworms are herein reported. We also demonstrated that DNA strand breakage and immune cells frequency are important endpoints to be employed in the earthworm reproduction assay, for the evaluation of soil geno and cytotoxicity, as part of the risk assessment of contaminated areas. This is the first study that integrates DNA damage and cytotoxicity evaluation, growth and bioaccumulation of metals and radionuclides in a sub lethal assay, for earthworms exposed to soil contaminated with metals and radionuclides. PMID:21146299

  1. Investigation of exposure rates and radionuclide and trace metal distributions along the Hanford Reach of the Columbia River

    SciTech Connect

    Cooper, A.T.; Woodruff, R.K.

    1993-09-01

    Studies have been conducted to investigate exposure rates, and radionuclide and trace metal distributions along the Columbia River where it borders the Hanford Site. The last major field study was conducted in 1979. With recently renewed interest in various land use and resource protection alternatives, it is important to have data that represent current conditions. Radionuclides and trace metals were surveyed in Columbia River shoreline soils along the Hanford Site (Hanford Reach). The work was conducted as part of the Surface Environmental Surveillance Project, Pacific Northwest Laboratory. The survey consisted of taking exposure rate measurements and soil samples primarily at locations known or expected to have elevated exposure rates.

  2. [The distribution of the radionuclides in the main components of lake ecosystems within the Chernobyl NPP exclusion zone].

    PubMed

    2005-01-01

    The results of the studies devoted to the distribution of radionuclides 90Sr, 137Cs, 238Pu, 239 + 240Pu and 241Am in 1998-2003 in main components of Glubokoe Lake and Dalekoe-1 Lake located within Krasnensky flood lands of the Pripyat River (inner exclusion zone of the Chernobyl NPP) were analysed. The data about the radionuclide content in bottom sediments, in water, in seston, in macrozoobenthos (including bivalvia molluscs), in gasteropods molluscs, in higher aquatic plants and in fish are presented. PMID:16080615

  3. Natural Radionuclides In Mineral Sand Products From A Processing Plant In Northeastern Brazil

    SciTech Connect

    Hazin, C. A.; Khoury, H. J.; Silveira, S. V.

    2008-08-07

    This paper presents the results of a preliminary investigation carried out in a mineral sand processing plant located in the coastal region of Northeastern Brazil. The study aimed to determine the natural radionuclide content of the mineral products extracted from beach sands, with special emphasis on zircon. Measurements were performed through gamma spectrometry, by using a high-purity germanium detector (HPGe) coupled to a multichannel analyzer. Activity concentrations of {sup 226}Ra and {sup 228}Ra were determined by measuring some of the radon progeny activity concentrations ({sup 214}Pb and {sup 214}Bi for {sup 226}Ra, and {sup 228}Ac and {sup 208}Tl for {sup 228}Ra) and assuming an equilibrium condition upstream of the radon progeny. The results of the measurements carried out for the zircon samples showed activity concentrations ranging from 18.09 to 48.51 kBq kg{sup -1} for {sup 226}Ra. The results for {sup 228}Ra, on the other hand, were consistently lower than those obtained for {sup 226}Ra, ranging from 2.72 to 18.31 kBq kg{sup -1}.

  4. Natural radionuclides in Austrian mineral water and their sequential measurement by fast methods.

    PubMed

    Wallner, Gabriele; Wagner, Rosmarie; Katzlberger, Christian

    2008-07-01

    Ten samples of Austrian mineral water were investigated with regard to the natural radionuclides (228)Ra, (226)Ra, (210)Pb, (210)Po, (238)U and (234)U. The radium isotopes as well as (210)Pb were measured by liquid scintillation counting (LSC) after separation on a membrane loaded with element-selective particles (Empore Radium Disks) and (210)Po was determined by alpha-spectroscopy after spontaneous deposition onto a copper planchette. Uranium was determined by ICP-MS as well as by alpha-spectroscopy after ion separation and microprecipitation with NdF(3). From the measured activity concentrations the committed effective doses for adults and babies were calculated and compared to the total indicative dose of 0.1 mSv/a given in the EC Drinking Water Directive as a maximum dose. The dominant portion of the committed effective dose was due to the radium isotopes; the dose from (228)Ra in most samples clearly exceeded the dose from (226)Ra. PMID:18243442

  5. Disequilibrium study of natural radionuclides of uranium and thorium series in cores and briny groundwaters from Palo Duro Basin, Texas

    SciTech Connect

    Laul, J.C.; Smith, M.R.

    1988-05-01

    The concentrations of natural radionuclides of the /sup 238/U and /232/Th series are reported in several cores and in ten deep and five shallow briny groundwaters from various formations in the Palo Duro Basin. The formations include Granite Wash, Pennsylvanian Granite Wash, Wolfcamp Carbonate, Pennsylvanian Carbonate, Seven River, Queen Grayburg, San Andres, Yates and Salado. The natural radionuclide data in cores suggest that the radionuclides have not migrated or been leached for at least a period of about 1 million years. Relative to the U and Th concentrations in cores, the brines are depleted by a factor of 10/sup 4/ to 10/sup 5/, indicating extremely low solubility of U and Th in brines. The natural radionuclide data in brines suggest that radium is not sorbed significantly and thus not retarded in nine deep brines. Radium is somewhat sorbed in one deep brine of Wolfcamp Carbonate and significantly sorbed in shallow brines. Relative to radium, the U, Th, Pb, Bi, and Po radionuclides are highly retarded by sorption. The retardation factors for /sup 228/Th range from 10/sup 2/ to 10/sup 3/, whereas those for /sup 230/Th and /sup 234/U range from 10/sup 3/ to 10/sup 5/, depending on the formation. The /sup 234/U//sup 238/U ratios in these brines are constant at about 1.5. The magnitude of the /sup 234/U//sup 230/Th ratio appears to reflect the degree of redox state of the aquifer's environment. The /sup 234/U//sup 230/Th ratio in nine deep brines is about unity, suggesting that U, like Th/sup +4/, is in the +4 state, which in turn suggests a reduced environment. 49 refs., 23 figs., 18 tabs.

  6. State of radionuclides in seawater. Comparison of natural stable and artificial radioactive isotope s of mercury and zinc in natural waters of the arid zone of the USSR

    SciTech Connect

    Rakhmatov, U; Khikmatov, K; Kist, A.A.; Kulmatov, R.A.; Teshabaev, S.T.; Volkov, A.A.

    1986-09-01

    This paper studies the state of stable and artificial radioactive isotopes of merury and zinc in natural waters of the arid zone of the USSR by radioactivity and radiochemical methods. Convergent results have been obtained for the dissolved forms of mercury and zinc in natural waters of the arid zone in a comparison of the results of radioactivation analysis and laboratory simulation using the radionuclides mercury-203 and zinc-65.

  7. Gamma-ray methods for determining natural and anthropogenic radionuclides in environmental and soil science

    SciTech Connect

    Harbottle, G.; Evans, C.V.

    1997-05-01

    Gamma-ray methods for the determination of radionuclides in environmental materials are convenient because they generally require less bench-top preparation time than, for example, determinations based on alpha-particle pulse-height analysis. Also, parallel measurements of chemical yield are not needed, and typically several radionuclides can be determined simultaneously. In this paper, the authors review gamma-ray methods currently in use at Brookhaven, and present a new method for the determination of the radionuclide protactinium-231 in soils and other environmental materials, using the gamma-ray deconvolution package in the EG&G Ortec {open_quotes}Gammavision{close_quotes} software.

  8. Low level measurements of natural radionuclides in soil samples around a coal-fired power plant

    NASA Astrophysics Data System (ADS)

    Rosner, G.; Bunzl, K.; Hötzl, H.; Winkler, R.

    1984-06-01

    To detect a possible contribution of airborne radioactivity from stack effluents to the soil radioactivity, several radionuclides in the soil around a coal-fired power plant have been determined. A plant situated in a rural region of Bavaria was selected to minimize contributions from other civilisatory sources. The soil sampling network consisted of 5 concentric circles with diameters between 0.4 and 5.2 km around the plant, 16 sampling points being distributed regularly on each circle. Radiochemical analysis techniques for 210Pb and 210Po in soil samples of several grams had to be developed. They include a wet dissolution procedure, simultaneous precipitation of lead and polonium as the sulfides, purification via lead sulfate, counting of the lead as the chromate in a low-level beta counter and alpha spectrometric determination of the 210Po in a gridded ionization chamber. The 238U, 226Ra, 232Th and 40K were counted by low level gamma spectrometry. Specific activities found were in the range of 0.7 to 2.0 pCi g -1 for 210Pb and 0.3 to 1.6 pCi g -1 for 226Ra. The distribution patterns of 210Po and 210Pb around the plant were found to be similar. They were different, however, from that of 226Ra. The highest 210Pb/ 226Ra activity ratio was 3.9 at a distance of 0.76 km SSE from the plant. Nevertheless, the evidence is not considered to be sufficient to attribute these observations unambiguously to plant releases.

  9. Vertical distribution of anthropogenic radionuclides in cores from contaminated floodplains of the Yenisey River.

    PubMed

    Standring, W J F; Brown, J E; Dowdall, M; Korobova, E M; Linnik, V G; Volosov, A G

    2009-12-01

    The Mining and Chemical Industrial Combine, Zheleznogorsk (MCIC, previously known as Krasnoyarsk-26) on the River Yenisey has contaminated the surrounding environment with anthropogenic radionuclides as a result of discharges of radioactive wastes. The purpose of this study was to investigate the vertical distribution of anthropogenic contamination ((137)Cs and plutonium) within floodplain areas at different distances from the discharge point. Sites were chosen that display different characteristics with respect to periodic inundation with river water. Cs-137 activity concentrations were in the range 23-3770 Bq/kg (dry weight, d.w.); Pu-239,240 activity concentrations were in the range <0.01-14.2 Bq/kg (d.w.). Numerous sample cores exhibited sub-surface maxima which may be related to the historical discharges from the MCIC. Possible evidence indicating the deposition of earlier discharges at MCIC in deeper core layers was observed in the (238)Pu:(239,240)Pu activity ratio data: a Pu signal discernible from global fallout could be observed in numerous samples. Cs-137 and Pu-239,240 activity concentrations were correlated with the silt fraction (% by mass <63 microm) though no significant correlation was observed between (grain-size) normalised (137)Cs activity concentrations and distance downstream from the MCIC. PMID:19446379

  10. Radionuclide Migration at the Rio Blanco Site, A Nuclear-stimulated Low-permeability Natural Gas Reservoir

    SciTech Connect

    Clay A. Cooper; Ming Ye; Jenny Chapman; Craig Shirley

    2005-10-01

    The U.S. Department of Energy and its predecessor agencies conducted a program in the 1960s and 1970s that evaluated technology for the nuclear stimulation of low-permeability gas reservoirs. The third and final project in the program, Project Rio Blanco, was conducted in Rio Blanco County, in northwestern Colorado. In this experiment, three 33-kiloton nuclear explosives were simultaneously detonated in a single emplacement well in the Mesaverde Group and Fort Union Formation, at depths of 1,780, 1,899, and 2,039 m below land surface on May 17, 1973. The objective of this work is to estimate lateral distances that tritium released from the detonations may have traveled in the subsurface and evaluate the possible effect of postulated natural-gas development on radionuclide migration. Other radionuclides were considered in the analysis, but the majority occur in relatively immobile forms (such as nuclear melt glass). Of the radionuclides present in the gas phase, tritium dominates in terms of quantity of radioactivity in the long term and contribution to possible whole body exposure. One simulation is performed for {sup 85}Kr, the second most abundant gaseous radionuclide produced after tritium.

  11. Distribution pattern of artificial radionuclides in the Baltic Sea in the special event of the Chernobyl fallout.

    PubMed

    Weiss, Dietmar

    2011-09-01

    Extensive investigations on radioactive contamination and on its spatial and temporal changes in the Baltic Sea have been carried out by the National Board for Atomic Safety and Radiation Protection since 1986. The results were compared with data obtained in the years prior to the Chernobyl accident. Due to the composition of the accidental releases and the physical half-life of the released radionuclides, special emphasis was laid on Cs-134 and Cs-137. Other radionuclides, such as H-3, Sr-90, Ru-103 and Ru-106 turned out to be insignificant compared with the caesium isotopes. The radionuclides Cs-134 and Cs-137 accounting for the highest percentage of the released long-lived radionuclides were deposited on the sea surface with an initial ratio of 0.5. Their distribution pattern on the sea surface was affected by the meteorological conditions prevailing during the release period. The horizontal dislocation of higher contaminated water masses and the vertical penetration of radioactive caesium resulted in a prolonged uniformity of the contamination level of the Baltic Sea. PMID:21809941

  12. Selected natural and fallout radionuclides in plant foods around the Kudankulam Nuclear Power Project, India.

    PubMed

    Ross, E Mahiban; Raj, Y Lenin; Wesley, S Godwin; Rajan, M P

    2013-01-01

    The activity concentrations of certain radionuclides were quantified in some plant foods cultivated around Kudankulam, where a mega-nuclear power plant is being established. The activity concentrations were found more in the 'pulses' group and were the lowest in 'other vegetable' category. The annual effective dose was computed based on the activity concentration of radionuclides and it was found to be higher due to the consumption of cereals and pulses. Other vegetables, cereals, pulses and nuts recorded high transfer factors for the radionuclide (228)Ra. Fruits, leafy vegetables, tubers and roots, and palm embryo registered high transfer factors for (226)Ra. Group-wise activity concentration, radiation dose to the public and soil-plant-to-transfer factor are discussed in detail. PMID:23017443

  13. Lixiviation of natural radionuclides and heavy metals in tropical soils amended with phosphogypsum.

    PubMed

    Nisti, M B; Saueia, C R; Malheiro, L H; Groppo, G H; Mazzilli, B P

    2015-06-01

    The main phosphate industries in Brazil are responsible for the annual production of 5.5 million tons of a residue (phosphogypsum), which is stored in stacks. The presence of radionuclides and metals puts restrictions on the use of phosphogypsum in agriculture. To assure a safe utilization, it is important to estimate the lixiviation of the radionuclides ((238)U, (226)Ra, (210)Pb, (210)Po, (232)Th and (228)Ra) and metals (As, Cd, Cr, Ni, Se, Hg and Pb) present in phosphogypsum. For this purpose, an experiment was carried out, in which columns filled with sandy and clay Brazilian typical soils mixed with phosphogypsum were percolated with water, to achieve a mild extraction of these elements. The results obtained for the concentration of the radionuclides and metals in the leachate were low; giving evidence that, even when these elements are present in the phosphogypsum, they do not contribute to an enhancement of their content in water. PMID:25841114

  14. Soil-to-Crop Transfer Factors of Naturally Occurring Radionuclides and Stable Elements for Long-Term Dose Assessment

    SciTech Connect

    Uchida, S.; Tagami, K.

    2007-07-01

    A soil-to-crop transfer factor, TF, is a key parameter that directly affects the internal dose assessment for the ingestion pathway, however, obtaining TFs of various long-lived radionuclides occurred during operation of nuclear power plants is difficult because most of them could not be found in natural environments. In this study, therefore, we collected crops and their associated soils throughout Japan and measured more than 50 elements to obtain TFs under equilibrium conditions. The TFs were calculated for 42 elements (Li, Na, Mg, Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Mo, Cd, Sn, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tl, Pb, Th and U) from their concentrations in both crop and soil samples. The TF is defined as the concentration of an isotope in a crop (in Bq/kg or mg/kg dry weight) divided by the concentration of the isotope in soil (in Bq.kg or mg/kg dry weight). Probability distributions of TFs for 62 upland field crops were usually log-normal type so that geometric means (GMs) were calculated. The values for the elements of interest from the viewpoint of long-term dose assessment were 2.5E-02 for Se, 7.9E-02 for Sr, 3.1E-03 for Cs, 4.2E-04 for Th and 4.6E-04 for U. Leafy vegetable showed the highest TFs for all the elements among the crop groups. It was clear that these data were usually within the 95% confidence limits of TFs compiled by IAEA in Technical Report Series 364. (authors)

  15. Assessment of indoor absorbed gamma dose rate from natural radionuclides in concrete by the method of build-up factors.

    PubMed

    Manić, Vesna; Nikezic, Dragoslav; Krstic, Dragana; Manić, Goran

    2014-12-01

    The specific absorbed gamma dose rates, originating from natural radionuclides in concrete, were calculated at different positions of a detection point inside the standard room, as well as inside an example room. The specific absorbed dose rates corresponding to a wall with arbitrary dimensions and thickness were also evaluated, and appropriate fitting functions were developed, enabling dose rate calculation for most realistic rooms. In order to make calculation simpler, the expressions fitting the exposure build-up factors for whole (238)U and (232)Th radionuclide series and (40)K were derived in this work, as well as the specific absorbed dose rates from a point source in concrete. Calculated values of the specific absorbed dose rates at the centre point of the standard room for (238)U, (232)Th and (40)K are in the ranges of previously obtained data. PMID:24421381

  16. Investigation of the environmental impacts of naturally occurring radionuclides in the processing of sulfide ores for gold using gamma spectrometry.

    PubMed

    Gbadago, J K; Faanhof, A; Darko, E O; Schandorf, C

    2011-09-01

    The possible environmental impacts of naturally occurring radionuclides on workers and a critical community, as a result of milling and processing sulfide ores for gold by a mining company at Bogoso in the western region of Ghana, have been investigated using gamma spectroscopy. Indicative doses for the workers during sulfide ore processing were calculated from the activity concentrations measured at both physical and chemical processing stages. The dose rate, annual effective dose equivalent, radium equivalent activity, external and internal hazard indices, and radioactivity level index for tailings, for the de-silted sediments of run-off from the vicinity of the tailings dam through the critical community, and for the soils of the critical community's basic schools were calculated and found to be lower than their respective permissible limits. The environmental impact of the radionuclides is therefore expected to be low in this mining environment. PMID:21865616

  17. RADIONUCLIDE INVENTORY AND DISTRIBUTION: FOURMILE BRANCH, PEN BRANCH, AND STEEL CREEK IOUS

    SciTech Connect

    Hiergesell, R.; Phifer, M.

    2014-04-29

    As a condition to the Department of Energy (DOE) Low Level Waste Disposal Federal Facility Review Group (LFRG) review team approving the Savannah River Site (SRS) Composite Analysis (CA), SRS agreed to follow up on a secondary issue, which consisted of the consolidation of several observations that the team concluded, when evaluated collectively, could potentially impact the integration of the CA results. This report addresses secondary issue observations 4 and 21, which identify the need to improve the CA sensitivity and uncertainty analysis specifically by improving the CA inventory and the estimate of its uncertainty. The purpose of the work described herein was to be responsive to these secondary issue observations by re-examining the radionuclide inventories of the Integrator Operable Units (IOUs), as documented in ERD 2001 and Hiergesell, et. al. 2008. The LFRG concern has been partially addressed already for the Lower Three Runs (LTR) IOU (Hiergesell and Phifer, 2012). The work described in this investigation is a continuation of the effort to address the LFRG concerns by re-examining the radionuclide inventories associated with Fourmile Branch (FMB) IOU, Pen Branch (PB) IOU and Steel Creek (SC) IOU. The overall approach to computing radionuclide inventories for each of the IOUs involved the following components: • Defining contaminated reaches of sediments along the IOU waterways • Identifying separate segments within each IOU waterway to evaluate individually • Computing the volume and mass of contaminated soil associated with each segment, or “compartment” • Obtaining the available and appropriate Sediment and Sediment/Soil analytical results associated with each IOU • Standardizing all radionuclide activity by decay-correcting all sample analytical results from sample date to the current point in time, • Computing representative concentrations for all radionuclides associated with each compartment in each of the IOUs • Computing the

  18. Direct intratumoral infusion of liposome encapsulated rhenium radionuclides for cancer therapy: Effects of nonuniform intratumoral dose distribution

    SciTech Connect

    Hrycushko, Brian A.; Li Shihong; Goins, Beth; Otto, Randal A.; Bao, Ande

    2011-03-15

    Purpose: Focused radiation therapy by direct intratumoral infusion of lipid nanoparticle (liposome)-carried beta-emitting radionuclides has shown promising results in animal model studies; however, little is known about the impact the intratumoral liposomal radionuclide distribution may have on tumor control. The primary objective of this work was to investigate the effects the intratumoral absorbed dose distributions from this cancer therapy modality have on tumor control and treatment planning by combining dosimetric and radiobiological modeling with in vivo imaging data. Methods: {sup 99m}Tc-encapsulated liposomes were intratumorally infused with a single injection location to human head and neck squamous cell carcinoma xenografts in nude rats. High resolution in vivo planar imaging was performed at various time points for quantifying intratumoral retention following infusion. The intratumoral liposomal radioactivity distribution was obtained from 1 mm resolution pinhole collimator SPECT imaging coregistered with CT imaging of excised tumors at 20 h postinfusion. Coregistered images were used for intratumoral dosimetric and radiobiological modeling at a voxel level following extrapolation to the therapeutic analogs, {sup 186}Re/{sup 188}Re liposomes. Effective uniform dose (EUD) and tumor control probability (TCP) were used to assess therapy effectiveness and possible methods of improving upon tumor control with this radiation therapy modality. Results: Dosimetric analysis showed that average tumor absorbed doses of 8.6 Gy/MBq (318.2 Gy/mCi) and 5.7 Gy/MBq (209.1 Gy/mCi) could be delivered with this protocol of radiation delivery for {sup 186}Re/{sup 188}Re liposomes, respectively, and 37-92 MBq (1-2.5 mCi)/g tumor administered activity; however, large intratumoral absorbed dose heterogeneity, as seen in dose-volume histograms, resulted in insignificant values of EUD and TCP for achieving tumor control. It is indicated that the use of liposomes encapsulating

  19. ASSESSMENTOF BETA PARTICLE FLUX FROM SURFACE CONTAMINATION AS A RELATIVE INDICATOR FOR RADIONUCLIDE DISTRIBUTION ON EXTERNAL SURFACES OF A MULTI-STORY BUILDING IN PRIPYAT

    SciTech Connect

    Farfan, E.

    2009-11-17

    How would we recover if a Radiological Dispersion Device (e.g., dirty bomb) or Improvised Nuclear Device were to detonate in a large city? In order to assess the feasibility of remediation following such an event, several issues would have to be considered, including the levels and characteristics of the radioactive contamination, the availability of the required resources to accomplish decontamination, and the planned future use of the city's structures and buildings. Presently little is known about the distribution, redistribution, and migration of radionuclides in an urban environment. However, Pripyat, a city substantially contaminated by the Chernobyl Nuclear Power Plant accident, may provide some answers. The main objective of this study was to determine the radionuclide distribution on a Pripyat multi-story building, which had not been previously decontaminated and therefore could reflect the initial fallout and its further natural redistribution on external surfaces. The 7-story building selected was surveyed from the ground floor to the roof on horizontal and vertical surfaces along seven ground-to-roof transections. Some of the results from this study indicate that the upper floors of the building had higher contamination levels than the lower floors. The authors consequently recommend that existing decontamination procedures for tall structures be re-examined and modified accordingly.

  20. Assessment of beta particle flux from surface contamination as a relative indicator for radionuclide distribution on external surfaces of a multistory building in Pripyat.

    PubMed

    Farfán, Eduardo B; Gaschak, Sergii P; Maksymenko, Andriy M; Jannik, G Tim; Marra, James C; Bondarkov, Mikhail D; Donnelly, Elizabeth H

    2011-02-01

    Several issues should be considered when assessing the feasibility of remediation following the detonation of a radiological dispersion device (e.g., dirty bomb) or improvised nuclear device in a large city. These issues include the levels and characteristics of the radioactive contamination, the availability of resources required for decontamination, and the planned future use of the city's structures and buildings. Presently, little is known about the distribution, redistribution, and migration of radionuclides in an urban environment. However, Pripyat, a city substantially contaminated by the Chernobyl Nuclear Power Plant accident in April 1986, may provide some answers. The main objective of this study was to determine the radionuclide distribution on a Pripyat multistory building that had not been decontaminated and, therefore, could reflect the initial fallout and its further natural redistribution on external surfaces over 23 y. The seven-story building selected was surveyed from the ground floor to the roof on horizontal and vertical surfaces along seven ground-to-roof transections. Some results from this study indicate that the upper floors of the building had higher contamination levels than the lower floors. Consequently, the authors recommend that thorough decontamination should be considered for all the floors of tall buildings (not just lower floors). PMID:21399438

  1. Seasonality in the flux of natural radionuclides and plutonium in the deep Sargasso Sea. Technical report

    SciTech Connect

    Bacon, M.P.; Fleer, A.P.; Deuser, W.G.

    1985-01-01

    A record of radionuclide fluxes at a deep-ocean station near Bermuda (32/sup 0/ 05 min N, 64/sup 0/ 15 min W) was obtained from analysis of a 3-year collection of sediment-trap samples. The trap was placed at a depth of 3200 m, 1000 m above the sea floor, and the samples were recovered at 2-month intervals. Concentrations of U-238, -234, Th-232, -230, -228, Pa-231, Pb-210, Po-210, and Pu-239 and -240 were measured in the trapped material. Most of the radionuclide activity was found in the <37-micron sieved fraction. All radionuclide fluxes showed seasonal variations in phase with the variations in total sediment flux, which had been previously shown to be closely tied to the annual cycle of primary production in the overlying surface water. Seasonal variations are especially noteworthy for Th-230 and Pa-231, considering that most of their production occurs in the water column below the euphotic zone. Evidently the seasonal influence is transmitted downward by the varying particle flux so that radionuclide scavenging rates at depth, as well as at the surface, are affected. It is suggested that this could be brought about by seasonal variations in the flux of marine snow or in the rate of fecal-matter production in the deep-water column. Keywords: Pelagic sedimentation.

  2. DISTRIBUTION AND SOLUBILITY OF RADIONUCLIDES AND NEUTRON ABSORBERS IN WASTE FORMS FOR DISPOSITION OF PLUTONIUM ASH AND SCRAPS, EXCESS PLUTONIUM, AND MISCELLANEOUS SPENT NUCLEAR FUELS

    EPA Science Inventory

    The objective of this multi-institutional, multi-national research effort is to understand the distributions, solubilities, and releases of radionuclides and neutron absorbers in waste forms. The results will provide the underpinning knowledge for developing, evaluating, selectin...

  3. Distribution and transport kinetics of radionuclides sup 99 Mo and sup 131 I in a simulated aquatic ecosystem

    SciTech Connect

    Svadlenkova, M.; Konecny, J.; Obdrzalek, M.; Simanov, L. )

    1990-04-01

    Radioactive liquid wastes from nuclear power stations increase the activity not only of water but also of sediment, aquatic and shore plants, and animals. On average, the majority of the total radioactivity brought to the aquatic system is absorbed by the sediment; the remaining fraction is distributed between water and biomass. For us to be able to assess the influence of the nuclear power station at Temelin in South Bohemia on the nearby hydrosphere, the authors concentrated first on the experimental investigation of the distribution and transport kinetics of some radionuclides in a simulated aquatic system.

  4. Sorption and diffusion of radionuclides in rock matrix and natural fracture surfaces studied by autoradiography

    SciTech Connect

    Muuronen, S.; Kaemaeraeinen, E.L.; Jaakkola, T.; Pinnioja, S.; Lindberg, A.

    1986-01-01

    A method based on autoradiography was developed to determine the sorption and diffusion of cesium, strontium, cobalt, nickel, iodine and americium into rock matrix. Samples chosen for this study were filled and unfilled natural fracture surfaces and drill cores having a central drilled hole (drill core cups). Rock types were mica gneiss, tonalite and rapakivi granite, which were selected to represent the common rocks and minerals in Finnish bedrock. Distribution coefficients (K/sub a/-values) of cesium and strontium determined for fissure surfaces and drill core cups were of the same order of magnitude. After three months contact time the greatest penetration depth for cesium was 2.5 mm, for a natural fissure surface sample of rapakivi granite. For strontium the penetration depths of 11 mm in three months and 35 mm in twelve months were found for filled natural fissure surface samples of rapakivi granite. The range of D/sub a/-values was 1.5 x 10/sup -15/ - 3.2 x 10/sup -14/ m/sup 2//s and 1.4 x 10/sup -14/ - 2.1 x 10/sup -13/ m/sup 2//s for cesium and strontium, resp. For cobalt the D/sub a/-values of 5 x 10/sup -16/ m/sup 2//s in tonalite was obtained. In six months the penetration depths of nickel, iodine and americium were too low (<0.5 mm) to allow calculation of D/sub a/.

  5. Temporal variations of natural and anthropogenic radionuclides in sea otter skull tissue in the North Pacific Ocean

    USGS Publications Warehouse

    Baskaran, M.; Hong, G.-H.; Dayton, S.; Bodkin, J.L.; Kelley, J.J.

    2002-01-01

    Marine mammals being among the top predators in the food web tend to accumulate organic and inorganic contaminants from the environment. The body burden of contaminants in these species could reflect their foods and thus contaminant levels could serve as proxies on the changes of ecosystem. A pilot study was carried out to investigate the possibility of radionuclide leakage at Amchitka using a suite of sea otter (Enhydra lutris) skulls collected near Amchitka nuclear test-sites before (1950s) and after the testing (1990s), and at Adak, another Aleutian Island, about 300 km from Amchitka, where the potential impact of radionuclide leakage from Amchitka is expected to be negligible. In addition, the naturally occurring and anthropogenic radionuclide content on the sea otter skull was also utilized to investigate if there was any significant ecosystem changes in the environment. Concentration of 210Pb in sea otter bones collected during the 1950s was significantly higher than those collected in the 1990s. We propose that among the various factors that could cause this higher enrichment in 210Pb, changes in the sea otter prey is the most likely one. Comparison of the 137Cs, 90Sr, 239,240Pu concentrations appear not to be significantly higher in sea otter skulls collected in 1990s from Amchitka where the underground tests in 1965-71 than those from Adak, although significant differences were detected among different groups collected at various times. ?? 2002 Elsevier Science Ltd. All rights reserved.

  6. Temporal variations of natural and anthropogenic radionuclides in sea otter skull tissue in the North Pacific Ocean

    USGS Publications Warehouse

    Baskaran, M.; Hong, G.-H.; Dayton, S.; Bodkin, J.L.; Kelly, J.J.

    2003-01-01

    Marine mammals being in the top predator in the food web tend to accumulate organic and inorganic contaminants from the environment. The body burden of contaminants in these species could reflect their foods and thus contaminant levels could serve as proxies on the changes of ecosystem. A pilot study was carried out to investigate the possibility of radionuclide leakage at Amchitka using a suite of sea otter (Enhydra lutris) skulls collected near Amchitka nuclear test-sites before (1950s) and after the testing (1990s), and at Adak, another Aleutian Island, about 300 km from Amchitka, where the potential impact of radionuclide leakage from Amchitka is expected to be negligible. In addition, the naturally occurring and anthropogenic radionuclide content on the sea otter skull was also utilized to investigate if there was any significant ecosystem changes in the environment. Concentration of 210Pb in sea otter bones collected during the 1950's was significantly higher than those collected in the 1990's. We propose that among the various factors that could cause this higher enrichment in 210Pb, changes in the sea otter prey is the most likely one. Comparison of the 137Cs, 90Sr, 239,240Pu concentrations appear not to be significantly higher in sea otter skulls collected in 1990s from Amchitka where the underground tests in 1965-71 than those from Adak, although significant differences were detected among different groups collected at various times.

  7. Application of sorption technique for decontamination of liquid radwaste and natural water from cesium and strontium radionuclides

    SciTech Connect

    Milyutin, V.V.; Gelis, V.M.; Penzin, R.A.

    1995-12-31

    In this paper the results obtained in field tests of decontaminating radioactive natural and industrial solutions of different chemical and radionuclide composition from cesium and strontium radionuclides are reported. Decontamination of industrial reservoir water at the Production Association Mayak (Chelyabinsk Region, Russia) was performed using CMP synthetic zeolite. Efficient decontamination of the feed water is achieved after preliminary precipitation of hardness salts in the form of carbonates. Decontamination of water from the pool for spent fuel element storage from {sup 137}Cs was conducted using NGA ferricyanide sorbent. Decontamination factors with respect to {sup 137}Cs of 400 have been reached, the installation throughput being 100,000 by (bed volumes). Decontamination of liquid radwaste at Murmansk Shipping Co was conducted with CFB, CMP synthetic zeolites and NGA ferricyanide sorbent as well. Decontamination of D and D solutions and wastes of the special laundry resulted in decontamination factors within the range of 20--400, 10--100, and 10--30 with respect to {sup 137}Cs, {sup 90}Sr, and total {beta}-activity, respectively. Installation throughput of 3,000--5,000 bv for zeolites and 8,000--10,000 bv for ferrocyanide sorbents has been reached. Results obtained prove the high efficiency of sorption technique for decontaminating solutions from cesium and strontium radionuclides.

  8. Mapping and modelling of radionuclide distribution on the ground due to the Fukushima accident.

    PubMed

    Saito, Kimiaki

    2014-08-01

    A large-scale environmental monitoring effort, construction of detailed contamination maps based on the monitoring data, studies on radiocaesium migration in natural environments, construction of a prediction model for the air dose rate distribution in the 80 km zone, and construction of a database to preserve and keep open the obtained data have been implemented as national projects. Temporal changes in contamination conditions were analysed. It was found that air dose rates above roads have decreased much faster than those above undisturbed flat fields. Further, the decreasing tendency was found to depend on land uses, magnitudes of initial dose rates and some other factors. PMID:24695555

  9. The detailed analysis of natural radionuclides dissolved in spa waters of the Kłodzko Valley, Sudety Mountains, Poland.

    PubMed

    Walencik-Łata, A; Kozłowska, B; Dorda, J; Przylibski, T A

    2016-11-01

    A survey was conducted to measure natural radioactivity in spa waters from the Kłodzko Valley. The main goal of this study was to determine the activity concentration of uranium, radium and radon isotopes in the investigated groundwaters. Samples were collected several times from 35 water intakes from 5 spas and 2 mineral water bottling plants. The authors examined whether the increased gamma radiation background, as well as the elevated values of radium and uranium content in reservoir rocks, have a significant impact on the natural radioactivity of these waters. The second objective of this research was to provide information about geochemistry of U, Ra, Rn radionuclides and the radiological and chemical risks incurred by ingestion of isotopes with drinking water. On the basis of results obtained, it is feasible to assess the health hazard posed by ingestion of natural radioactivity with drinking waters. Moreover, the data yielded by this research may be helpful in the process of verification of the application of these waters in balneotherapy. In addition, annual effective radiation doses resulting from the isotopes consumption were calculated on the basis of the evaluated activity concentrations. In dose assessment for uranium and radium isotopes, the authors provided values for different human age groups. The obtained uranium content in the investigated waters was compared with the currently valid regulations concerning the quality of drinking water. Based on the activity concentrations data, the activity isotopic ratios (234)U/(238)U, (226)Ra/(238)U, (222)Rn/(238)U, (222)Rn/(226)Ra and the correlations between radionuclides content were then examined. In brief, it may be concluded on the basis of the obtained results that radon solubility is inversely proportional to radium and uranium dissolution in environmental water circulation. The presented study allows conclusions to be drawn on the radionuclide circulation among different environmental biota: from

  10. Naturally occurring radionuclides and rare earth elements in weathered Japanese soil samples

    NASA Astrophysics Data System (ADS)

    Sahoo, Sarata; Hosoda, Masahiro; Prasad, Ganesh; Takahashi, Hiroyuki; Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Tokonami, Shinji; Uchida, Shigeo

    2013-08-01

    The activity concentrations of 226Ra and 228Ac in weathered Japanese soils from two selected prefectures have been measured using a γ-ray spectroscopy system with high purity germanium detector. The uranium, thorium, and rare earth elements (REEs) concentrations were determined from the same soil samples using inductively coupled plasma mass spectrometry (ICP-MS). For example, granitic rocks contain higher amounts of U, Th, and light REEs compared to other igneous rocks such as basalt and andesites. Therefore, it is necessary to understand the interaction between REEs and nature of soils since soils are complex heterogeneous mixture of organic and inorganic solids, water, and gases. In this paper, we will discuss about distribution pattern of 238U and 232Th along with REEs in soil samples of weathered acid rock (granite) collected from two prefectures of Japan: Hiroshima and Miyagi.

  11. Influence of mineralogical and heavy metal composition on natural radionuclide concentrations in the river sediments.

    PubMed

    Suresh, G; Ramasamy, V; Meenakshisundaram, V; Venkatachalapathy, R; Ponnusamy, V

    2011-10-01

    The natural radiation level has been determined for the sediment samples of the Ponnaiyar River with an aim of evaluating the radiation hazard. The mineralogical characterizations of the sediments have been carried out using the Fourier Transform Infrared (FTIR) spectroscopic technique. The relative distribution of major minerals is determined by calculating extinction coefficient. The concentration and spatial distribution of heavy metals (Pb, Cr, Cu, Zn and Ni) have been studied to understand the heavy metal contamination and its level of toxicity. To evaluate the potential toxicity, heavy metal concentrations are compared with different toxicological and geological reference values. The comparison results suggest that the present metals create an adverse effect on the aquatic ecosystems associated with this river. To assess the sediment contamination due to the studied heavy metals, the Pollution Load Index (PLI) is calculated. Multivariate Statistical analyses (Pearson Correlation, Cluster and Factor analysis) were carried out between the parameters obtained from radioactivity, mineralogical and geochemical analysis to know the existing relations. Obtained results showed that the effect of mineralogy on level of radioactivity should be significant. However, mineralogy effect on heavy metal composition in the sediments should be limited, indicating that other factors such as vicinity of the pollution sources are more important. Also, the influence of mineralogical characterization on level of radioactivity is significant, whereas the influence of the heavy metal composition on level of radioactivity should be limited. PMID:21636283

  12. Developing of Watershed Radionuclide Transport Model DHSVM-R as Modification and Extension of Distributed Hydrological and Sediment Dynamics Model DHSVM

    NASA Astrophysics Data System (ADS)

    Zheleznyak, M.; Kivva, S.; Onda, Y.; Nanba, K.; Wakiyama, Y.; Konoplev, A.

    2015-12-01

    The reliable modeling tools for prediction wash - off radionuclides from watersheds are needed as for assessment the consequences of accidental and industrial releases of radionuclides, as for soil erosion studies using the radioactive tracers. The distributed model of radionuclide transport through watershed in exchangeable and nonexchangeable forms in solute and with sediments was developed and validated for small Chernobyl watersheds in 90th within EU SPARTACUS project (van der Perk et al., 1996). New tendency is coupling of radionuclide transport models and the widely validated hydrological distributed models. To develop radionuclide transport model DHSVM-R the open source Distributed Hydrology Soil Vegetation Model -DHSVM http://www.hydro.washington.edu/Lettenmaier/Models/DHSVM was modified and extended. The main changes provided in the hydrological and sediment transport modules of DHSVM are as follows: Morel-Seytoux infiltration model is added; four-directions schematization for the model's cells flows (D4) is replaced by D8 approach; the finite-difference schemes for solution of kinematic wave equations for overland water flow, stream net flow, and sediment transport are replaced by new computationally efficient scheme. New radionuclide transport module, coupled with hydrological and sediment transport modules, continues SPARTACUS's approach, - it describes radionuclide wash-off from watershed and transport via stream network in soluble phase and on suspended sediments. The hydrological module of DHSVM-R was calibrated and validated for the watersheds of Ukrainian Carpathian mountains and for the subwatersheds of Niida river flowing 137Cs in solute and with suspended sediments to Pacific Ocean at 30 km north of the Fukushima Daiichi NPP. The modules of radionuclide and sediment transport were calibrated and validated versus experimental data for USLE experimental plots in Fukushima Prefecture and versus monitoring data collected in Niida watershed. The role

  13. Activity concentration of natural radionuclides and radon and thoron exhalation rates in rocks used as decorative wall coverings in Japan.

    PubMed

    Iwaoka, Kazuki; Hosoda, Masahiro; Tabe, Hiroyuki; Ishikawa, Tetsuo; Tokonami, Shinji; Yonehara, Hidenori

    2013-01-01

    In Japan, many dwellings have decorative wall coverings made from granite, andesite, tuff, gabbro, and marble. However, information regarding activity concentrations and radon (Rn) and thoron (Rn) exhalation rates for such rocks is very scarce. Therefore, samples of the granite, andesite, tuff, and marble that are used as wall coverings in Japan were collected from mining companies, and their activity concentrations and Rn and Rn exhalation rates were measured. Dose estimations for inhabitants living in houses built with these materials were also carried out. The activity concentration of natural radionuclides in all the materials was lower than the critical values described by the International Atomic Energy Agency (IAEA) (10,000 Bq kg for K and 1,000 Bq kg for all other radionuclides of natural origin). The maximum values of Rn and Rn mass exhalation rates for the granite samples were 0.12 and 430 mBq kg s, and those for the area exhalation rates were 1.8 and 6300 mBq m s, respectively; these values are higher than those for other samples. The maximum value of effective doses to inhabitants was 0.68 mSv y, which is lower than the intervention exemption level (1 mSv y) given in the International Commission on Radiological Protection (ICRP) Publication 82. PMID:23192085

  14. The geographic distribution of radionuclide deposition across the continental US from atmospheric nuclear testing.

    PubMed

    Simon, Steven L; Bouville, André; Beck, Harold L

    2004-01-01

    For the first time, calculations for the more than 3000 counties of the US have been completed that estimate the average deposition density (Bq m(-2)) of more than 40 radionuclides in fallout from atmospheric nuclear weapons tests conducted in the US (1951-1962) and 19 radionuclides from tests conducted elsewhere in the world (1952-1963). The geographic pattern of deposition across the US, as well as the amount of fallout deposited, varied significantly depending on whether the tests were conducted within or outside of the US. Fallout deposited from the Nevada Test Site (NTS) varied geographically as a result of dispersion and dilution in the atmosphere, the wind patterns following each test, and the occurrence of localized rainfall events. In general, states immediately east of the NTS received the highest deposition from tests conducted there. In contrast, the variation in deposition across the country from global fallout was less than for NTS fallout primarily reflecting variations in annual precipitation across larger regions. Hence, in the eastern and mid-western US, where rainfall is above the national average, higher levels of global fallout were deposited than in the more arid southwestern states. This paper presents a summary of the methods used and findings of our studies on fallout from NTS and global fallout, with emphasis on two of the most important radionuclides, (131)I and (137)Cs. PMID:15063539

  15. Study of natural radionuclide concentrations in an area of elevated radiation background in the northern districts of Bangladesh.

    PubMed

    Hamid, B N; Chowdhury, M I; Alam, M N; Islam, M N

    2002-01-01

    The activity concentrations of naturally occurring radioactive materials in soil samples from an elevated radiation background area of three northern districts of Bangladesh were determined using gamma ray spectrometry. The outdoor and indoor external effective dose rates and the radiation hazard indices from these soil activities were evaluated. The dose rates were found to be about four times higher than the reported world average value. The concentration of natural radionuclides, derived radium equivalent activities and the representative level indices were also found to be higher. Recommendations on radiological and dosimetric measures have been suggested with an aim of minimising the harmful effects of ionising radiation to the population of the area concerned. PMID:11926374

  16. Natural Gas Hydrates: Occurrence, Distribution, and Detection

    NASA Astrophysics Data System (ADS)

    Paull, Charles K.; Dillon, William P.

    We publish this volume at a time when there is a growing interest in gas hydrates and major expansion in international research efforts. The first recognition of natural gas hydrate on land in Arctic conditions was in the mid-1960s (by I. Makogon) and in the seabed environment only in the early 1970s, after natural seafloor gas hydrate was drilled on the Blake Ridge during Deep Sea Drilling Project Leg 11. Initial scientific investigations were slow to develop because the study of natural gas hydrates is unusually challenging. Gas hydrate exists in nature in conditions of temperature and pressure where human beings cannot survive, and if gas hydrate is transported from its region of stability to normal Earth-surface conditions, it dissociates. Thus, in contrast to most minerals, we cannot depend on drilled samples to provide accurate estimates of the amount of gas hydrate present. Even the heat and changes in chemistry (methane saturation, salinity, etc.) introduced by the drilling process affect the gas hydrate, independent of the changes brought about by moving a sample to the surface. Gas hydrate has been identified in nature generally by inference from indirect evidence in drilling data or by using remotely sensed indications, mostly from seismic data. Obviously, the established techniques ofgeologic analysis, which require direct observation and sampling, do not apply to gas hydrate studies, and controversy has surrounded many interpretations. Pressure/temperature conditions appropriate for the existence of gas hydrate occur over the greater part of the shallow subsurface of the Earth beneath the ocean at water depths exceeding about 500 m (shallower beneath colder Arctic seas) and on land beneath high-latitude permafrost. Gas hydrate actually will be present in such conditions, however, only where methane is present at high concentrations. In the Arctic, these methane concentrations are often associated with petroleum deposits, whereas at continental margins

  17. Distribution of lake-bottom radionuclides measured with an underwater HPGe detector

    SciTech Connect

    Winn, W.G.; Dunn, D.L.; Bresnahan, P.J.

    1996-07-01

    This study at Savannah River was done to assist decisions on the future of L Lake, an artificial reservoir made in 1983-5 for additional cooling for L Reactor discharges. EG&G overflight NaI mappings prior to filling indicated that most of the man-made radionuclides were {sup 60}Co and (predominantly) {sup 137}Cs in the earlier stream beds lying beneath the lake. An underwater HPGe was used in 1995 to rapidly scope the present radiation levels at 96 locations in the lake. The present levels are in reasonable agreement with the earlier overflight mappings. 1 fig, 4 figs.

  18. Conversion factors for external gamma dose derived from natural radionuclides in soils.

    PubMed

    Quindos, L S; Fernández, P L; Ródenas, C; Gómez-Arozamena, J; Arteche, J

    2004-01-01

    Field in situ gamma radiation exposure rates and laboratory measured radioactivity contents of 1500 Spanish soils were compared. The main objective was to determine if published theoretically derived conversion factors would yield accurate quantitative activity concentration (Bq kg(-1)) for the data carried out in different surveys developed by our laboratory during the last ten years. The in situ external gamma dose rate results were compared to laboratory gamma analysis of soils samples gathered from each site, considering the concentrations of seven radionuclides: 40K, 214Pb, 214Bi, 212Bi, 212Pb, 208Tl and 228Ac. The coefficient of correlation found between these variables indicate a good relationship. A discussion of the factors contributing to the uncertainties as well as measurement procedure are also given in this paper. PMID:14567949

  19. Naturally-Occurring Radionuclides In Drinking Water From Surface And Groundwater Reservoirs

    SciTech Connect

    Carvalho, F. P.; Madruga, M. J.; Oliveira, J. M.; Lopes, I.; Ferrador, G.; Sequeira, M. M.

    2008-08-07

    Radioactivity in water for human consumption is under closer scrutiny than ever before and many countries adopted guideline values based on total alpha and total beta activity measurements. Although most waters from surface circulation meet these guidelines, it is frequently found that groundwater exceed guideline values. Results of water analyses by alpha spectrometry clarified that the main radionuclides present are from the uranium decay series, such as uranium isotopes, radium ({sup 226}Ra), radon ({sup 222}Rn), and also {sup 210}Pb and {sup 210}Po. Occasionally, groundwater displayed {sup 226}Ra concentrations higher than 1 Bq L{sup -1} and {sup 222}Rn concentrations above 1000 Bq L{sup -1}. Nevertheless, lack of conformity of these waters with guidelines adopted, generally, is not due to anthropogenic inputs.

  20. EVALUATING MONITORED NATURAL ATTENUATION FOR RADIONUCLIDE AND INORGANIC CONTAMINANTS IN GROUNDWATER

    EPA Science Inventory

    Monitored Natural Attenuation (MNA) for inorganic contaminants is dependent on naturally occurring processes in the subsurface that act without human intervention to reduce the mass, toxicity, mobility, volume or concentration of contaminants. EPA is developing a technical refer...

  1. Assessing Natural Radionuclide Migration in the Legacy Tailings of Uranium Production

    NASA Astrophysics Data System (ADS)

    Bondarenko, G.; Koliabina, I.; Marinich, O.

    2011-12-01

    The former Prydniprovsky Chemical Plant in Dniprodzerzhynsk, Ukraine, processed uranium ore from 1949 until 1991. Multiple tailing ponds containing solid residual waste products from the uranium leaching and processing of uranium were accumulated along the Dnieper River, including the largest, adjacent to the Dnieper Reservoir, containing over 12 million tons of tailings. Samples for this study were selected from a core recovered from the Dnieper tailing pit in 2009, and used to assess radionuclide migration from tailing ponds. Samples were selected from different depths of the tailing pit core, analyzed for total radionuclide concentrations [Marinich et al., 2009], and successively leached using distilled water, followed by 1N ammonium acetate solution, and finally by 1N HCl solution. Leaching times were ~24 h at 15.17 °C. 238U, 230Th and 226Ra leachate activities were measured by γ-spectrometry with a Ge(Li) detector. 210Pb activity was measured using a SEB-01 scintillation β-spectrometer. Errors depended on measuring method, radionuclide, activity and exposure time: 238U, 11.9%; 230Th, 10.9%; 226Ra, 9.3%; 210Pb ~30%. The average total 238U activity in the tailing profile was 4 Bq/g. The concentration of 238U in the water leachates increased with depth from 14.5% (7-7.5 m), to 43% (11-11.5 m). The concentration of 238U in the acid leachates behaved similarly, increasing from 5.5 % to 15.5% with depth. While the total 230Th activity in increased from 30 Bq/g (7-7.5 m) to 540 Bq/g (11-11.5 m), the 230Th concentration in ammonium acetate leachates decreased from ˜15% to ˜1%. The concentration of 226Ra in all leachates was <1%, indicating that, under conditions of the Dnieper tailing pit, 226Ra is essentially immobile. The concentration of 210Pb in the leachates was as high as 10%. In general, the magnitude of mobile activity from the Dnieper tailing pit core samples decreases in the order 238U>230Th≥210Pb> 226Ra. Secular radioactive equilibrium in the 238U

  2. Radionuclides as natural tracers for the characterization of fluids in regional discharge areas, Buda Thermal Karst, Hungary

    NASA Astrophysics Data System (ADS)

    Erőss, Anita; Mádl-Szőnyi, Judit; Surbeck, Heinz; Horváth, Ákos; Goldscheider, Nico; Csoma, Anita É.

    2012-03-01

    SummaryThe Buda Thermal Karst (Budapest, Hungary) developed in the regional discharge zone of a carbonate rock aquifer system. High radioactivity of the spring waters has already been reported in 1912, but there has been no detailed study and no consistent explanation for its origin. In this area mixing of cold and hot karst waters was hitherto assigned to be responsible for cave formation. However, the dissimilarity of the discharging waters within Budapest (in the North: Rózsadomb; in the South: Gellért Hill), may suggest also different cave forming processes. The application of radionuclides as natural tracers represents a novel approach to investigate these questions. For this study, we used uranium, radium and radon to identify mixing of fluids in the Buda Thermal Karst system and to infer the temperature and chemical composition of the end members. Chloride as a conservative component allowed the mixing ratios for the sampled waters to be calculated. Their fluid compositions were modeled and through the comparison of modeled and measured values, the end members were validated. As the result of this study, it was possible to characterize the mixing end members for the Rózsadomb area, whereas for the Gellért Hill discharge zone, mixing components could not be identified with the aid of radionuclides. Therefore, it is suggested that different processes are responsible for cave formation in these areas. In the Rózsadomb area, structurally-controlled mixing is the dominant cave forming process, whereas in the Gellért Hill area, due to the lack of mixing members, other processes have to be found, which are responsible for the formation of the caves, such as retrograde calcite solubility and/or geogenic acids, such as H2S. The application of radionuclides thus further supported the differences between the two study areas. This study identified moreover the source of elevated radon content of the waters in the Gellért Hill area in form of iron

  3. Naturally occurring radionuclides in materials derived from urban water treatment plants in southeast Queensland, Australia.

    PubMed

    Kleinschmidt, Ross; Akber, Riaz

    2008-04-01

    An assessment of radiologically enhanced residual materials generated during treatment of domestic water supplies in southeast Queensland, Australia, was conducted. Radioactivity concentrations of U-238, Th-232, Ra-226, Rn-222, and Po-210 in water, sourced from both surface water catchments and groundwater resources were examined both pre- and post-treatment under typical water treatment operations. Surface water treatment processes included sedimentation, coagulation, flocculation and filtration, while the groundwater was treated using cation exchange, reverse osmosis, activated charcoal or methods similar to surface water treatment. Waste products generated as a result of treatment included sediments and sludges, filtration media, exhausted ion exchange resin, backwash and wastewaters. Elevated residual concentrations of radionuclides were identified in these waste products. The waste product activity concentrations were used to model the radiological impact of the materials when either utilised for beneficial purposes, or upon disposal. The results indicate that, under current water resource exploitation programs, reuse or disposal of the treatment wastes from large scale urban water treatment plants in Australia do not pose a significant radiological risk. PMID:17980468

  4. Chemical methods for reduction of the transfer of radionuclides to farm animals in semi-natural environments.

    PubMed

    Hove, K

    1993-09-24

    The same chemicals can be used for reduction of radionuclide transfer to animals whether kept on farms or grazing in semi-natural and natural habitats. However, different techniques are required for administration of the active compounds. Dairy ruminants may be treated effectively by inclusion of chemicals in supplemental concentrates. Practical experience gained after the Chernobyl accident has shown that both clay minerals and hexacyanoferrates are effective in preventing high radiocaesium levels in animal products. Chemicals such as bentonite clays and CaCO3, used for reduction of 137Cs and 90Sr transfer respectively, must be fed in hectogram quantities and are only practical for dairy animals in semi-natural ecosystems. Salt licks and sustained release boli with hexacyanoferrates as caesium binders have been developed and used successfully after the Chernobyl accident for meat producing cattle, sheep and reindeer which graze freely for extended periods. Daily doses of 25-300 mg in sheep and 250-2000 mg in cows reduces 137Cs accumulation 2-10-fold. Binders for 90Sr have not been tested in grazing animals. Stable iodine could be provided in salt licks and indwelling rumen boli at rates required to block radioiodine uptake by the thyroid gland. Boli and salt licks are highly cost effective in reducing doses to man when compared to interdiction of food from farm animals. PMID:8248770

  5. Heavy metals in soils: distribution, relationship with soil characteristics and radionuclides and multivariate assessment of contamination sources.

    PubMed

    Dragović, S; Mihailović, N; Gajić, B

    2008-06-01

    The study is dealing with the distribution and the origin of heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) in soils from a priori non-polluted areas. Positive correlations with organic matter and clay content but not with pH have been observed for most of elements analyzed in this study. Correlations of some metals (Cr, Pb and Zn) and radionuclides (238U and 137Cs) observed for analyzed soils could be explained by their common affinity for clay minerals. Enrichment factor (EF) analysis and cluster analysis (CA) highlighted the lithogenic origin of Cr, Cu, Mn, Ni, Pb and Zn and pointed out the primary input of Cd from anthropogenic sources. It also revealed the need for detailed geochemical surveys in the future in order to decrease the uncertainty of discrimination between lithogenic and anthropogenic origin of metals of interest. PMID:18433832

  6. Quantification and Radiological Risk Estimation Due to the Presence of Natural Radionuclides in Maiganga Coal, Nigeria

    PubMed Central

    Kolo, Matthew Tikpangi; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Abdullah, Wan Hasiah Binti

    2016-01-01

    Following the increasing demand of coal for power generation, activity concentrations of primordial radionuclides were determined in Nigerian coal using the gamma spectrometric technique with the aim of evaluating the radiological implications of coal utilization and exploitation in the country. Mean activity concentrations of 226Ra, 232Th, and 40K were 8.18±0.3, 6.97±0.3, and 27.38±0.8 Bq kg-1, respectively. These values were compared with those of similar studies reported in literature. The mean estimated radium equivalent activity was 20.26 Bq kg-1 with corresponding average external hazard index of 0.05. Internal hazard index and representative gamma index recorded mean values of 0.08 and 0.14, respectively. These values were lower than their respective precautionary limits set by UNSCEAR. Average excess lifetime cancer risk was calculated to be 0.04×10−3, which was insignificant compared with 0.05 prescribed by ICRP for low level radiation. Pearson correlation matrix showed significant positive relationship between 226Ra and 232Th, and with other estimated hazard parameters. Cumulative mean occupational dose received by coal workers via the three exposure routes was 7.69 ×10−3 mSv y-1, with inhalation pathway accounting for about 98%. All radiological hazard indices evaluated showed values within limits of safety. There is, therefore, no likelihood of any immediate radiological health hazards to coal workers, final users, and the environment from the exploitation and utilization of Maiganga coal. PMID:27348624

  7. Quantification and Radiological Risk Estimation Due to the Presence of Natural Radionuclides in Maiganga Coal, Nigeria.

    PubMed

    Kolo, Matthew Tikpangi; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Abdullah, Wan Hasiah Binti

    2016-01-01

    Following the increasing demand of coal for power generation, activity concentrations of primordial radionuclides were determined in Nigerian coal using the gamma spectrometric technique with the aim of evaluating the radiological implications of coal utilization and exploitation in the country. Mean activity concentrations of 226Ra, 232Th, and 40K were 8.18±0.3, 6.97±0.3, and 27.38±0.8 Bq kg-1, respectively. These values were compared with those of similar studies reported in literature. The mean estimated radium equivalent activity was 20.26 Bq kg-1 with corresponding average external hazard index of 0.05. Internal hazard index and representative gamma index recorded mean values of 0.08 and 0.14, respectively. These values were lower than their respective precautionary limits set by UNSCEAR. Average excess lifetime cancer risk was calculated to be 0.04×10-3, which was insignificant compared with 0.05 prescribed by ICRP for low level radiation. Pearson correlation matrix showed significant positive relationship between 226Ra and 232Th, and with other estimated hazard parameters. Cumulative mean occupational dose received by coal workers via the three exposure routes was 7.69 ×10-3 mSv y-1, with inhalation pathway accounting for about 98%. All radiological hazard indices evaluated showed values within limits of safety. There is, therefore, no likelihood of any immediate radiological health hazards to coal workers, final users, and the environment from the exploitation and utilization of Maiganga coal. PMID:27348624

  8. Radionuclide Therapy

    NASA Astrophysics Data System (ADS)

    Zalutsky, M. R.

    Radionuclide therapy utilizes unsealed sources of radionuclides as a treatment for cancer or other pathological conditions such as rheumatoid arthritis. Radionuclides that decay by the emission of β and α particles, as well as those that emit Auger electrons, have been used for this purpose. In this chapter, radiochemical aspects of radionuclide therapy, including criteria for radionuclide selection, radionuclide production, radiolabeling chemistry, and radiation dosimetry are discussed.

  9. Transfer factors of natural radionuclides and (137)Cs from soil to plants used in traditional medicine in central Serbia.

    PubMed

    Djelic, Gorica; Krstic, Dragana; Stajic, Jelena M; Milenkovic, Biljana; Topuzovic, Marina; Nikezic, Dragoslav; Vucic, Dusica; Zeremski, Tijana; Stankovic, Milan; Kostic, Dragana

    2016-07-01

    Transfer factors of natural radionuclides and (137)Cs from soil to plants used in traditional medicine were determined. The transfer factors (TF) were calculated as Bq kg(-1) of dry plant per Bq kg(-1) of dry soil. Mass activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs in soil and plant samples were measured with high purity germanium detector (HPGe). The concentrations of As, Co, Cr, Cu, Mn, Ni, Pb and Zn were determined, as well as the cation exchange capacity (CEC) and the content of exchangeable cations (Ca, Mg, K, Na). Wide ranges of values were obtained for all the metals, especially for Cr and Ni. The Absalom model was used for determination of the amount of (137)Cs transferred from soil to plant based on soil characteristics such as pH, exchangeable potassium, humus and clay contents. The estimated transfer factors were in the range from 0.011 to 0.307 with an arithmetic mean of 0.071, median of 0.050, geometric mean of 0.053 and geometric standard deviation (GSD) of 2.08. This value agreed well with that calculated from the measurements of 0.069, geometric mean 0.040 and GSD 3.19. Correlations between radionuclides, metals, physicochemical properties and transfer factors were determined by Spearman correlation coefficient. There was a strong positive correlation between (137)Cs transfer factor and the ratio of transfer factor for K and (137)Cs. Principal Component Analysis (PCA) was performed in order to identify some pattern of data. PMID:27082759

  10. The uptake and distribution of buried radionuclides by pocket gophers (Thomomys bottae).

    PubMed

    Budd, R L; Gonzales, G J; Fresquez, P R; Lopez, E A

    2004-01-01

    Material Disposal Area G (Area G) at the Los Alamos National Laboratory is a low-level radioactive waste disposal facility. The noticeably high activity of pocket gophers on closed waste burial sites of various types at Area G resulted in the need to understand possible interactions between gophers and radioactive waste. Fossorial animals can influence the fate of contaminants by directly burrowing into waste trenches, pushing contaminated soil to the surface, or through indirect mechanisms such as consumption of contaminant-laden vegetation or the ingestion of soil. In our study, pocket gophers, mound soil, surface soil, and vegetation were collected at Area G and at offsite reference locations. The samples were analyzed for 241Am, 238Pu, 239Pu, 3H, and total U. It did not appear that gophers were responsible for any upward transport of radionuclides. Concentrations of 241Am, 238Pu, 239Pu, and 3H in some gophers, soil, and vegetation were higher than at reference sites; however, only 3H in gopher carcasses at only one of five sites within Area G was higher than a conservative ecological screening level. PMID:15055929

  11. Sediment transport and Hg recovery in Lavaca Bay, as evaluated from radionuclide and Hg distributions

    SciTech Connect

    Santschi, P.H.; Allison, M.A.; Asbill, S.; Perlet, A.B.; Cappellino, S.; Dobbs, C.; McShea, L.

    1999-02-01

    Mercury was released in the late 1960s from a chloralkali facility managed by ALCOA and deposited into sediments of Lavaca Bay, TX. Sediments have recorded this event as a well-defined subsurface concentration maximum. Radionuclide, mercury, X-radiography, and grain size data from sediment cores taken in 1997 at 15 stations in Lavaca bay were used to assess sediment and Hg movements in the bay. Sediment accumulation rates were calculated from bomb fallout nuclide ({sup 137}Cs, {sup 239,240}Pu) peaks in 1963 and from the steady-state delivery of {sup 210}Pb from the atmosphere. Sedimentation rates are highest at near-shore sites near the ALCOA facility and generally decrease away from shore. Sedimentation rates in some areas are likely influenced by anthropogenic activities such as dredging. Particle reworking, as assessed from {sup 7}Be measurements, is generally restricted to the upper 2--7 cm of sediments. Numerical simulations of Hg profiles using measured sedimentation and mixing parameters indicate that at most sites high remnant mercury concentrations at 15--60 cm depth cannot supply substantial amounts of Hg to surface sediments. Assuming no future Hg supplies, Hg concentrations in surface sediments are predicted to decrease exponentially with a recovery half-time of 4 {+-} 2 years.

  12. Humic substances in natural waters and their complexation with trace metals and radionuclides: a review. [129 references

    SciTech Connect

    Boggs, S. Jr.; Livermore, D.; Seitz, M.G.

    1985-07-01

    Dissolved humic substances (humic and fulvic acids) occur in surface waters and groundwaters in concentrations ranging from less than 1 mg(C)/L to more than 100 mg(C)/L. Humic substances are strong complexing agents for many trace metals in the environment and are also capable of forming stable soluble complexes or chelates with radionuclides. Concentrations of humic materials as low as 1 mg(C)/L can produce a detectable increase in the mobility of some actinide elements by forming soluble complexes that inhibit sorption of the radionuclides onto rock materials. The stability of trace metal- or radionuclide-organic complexes is commonly measured by an empirically determined conditional stability constant (K'), which is based on the ratio of complexed metal (radionuclide) in solution to the product concentration of uncomplexed metal and humic complexant. Larger values of stability constants indicate greater complex stability. The stability of radionuclide-organic complexes is affected both by concentration variables and envionmental factors. In general, complexing is favored by increased of radionuclide, increased pH, and decreased ionic strength. Actinide elements are generally most soluble in their higher oxidation states. Radionuclides can also form stable, insoluble complexes with humic materials that tend to reduce radionuclide mobility. These insoluble complexes may be radionuclide-humate colloids that subsequently precipitate from solution, or complexes of radionuclides and humic substances that sorb to clay minerals or other soil particulates strongly enough to immobilize the radionuclides. Colloid formation appears to be favored by increased radionuclide concentration and lowered pH; however, the conditions that favor formation of insoluble complexes that sorb to particulates are still poorly understood. 129 refs., 25 figs., 19 tabs.

  13. The use of lichen (Canoparmelia texana) as biomonitor of atmospheric deposition of natural radionuclides from U-238 and Th-232 series

    NASA Astrophysics Data System (ADS)

    Leonardo, Lucio; Damatto, Sandra Regina; Mazzilli, Barbara Paci; Saiki, Mitiko

    2008-08-01

    Lichens have been used in studies of environmental pollution monitoring of various air pollutants, especially heavy metals. This paper aims to study the possibility of using this specimen for the assessment of radionuclides deposition in the vicinity of a nuclear research institute, Instituto de Pesquisas Energéticas e Nucleares (IPEN) located in São Paulo, Brazil. This Institute has as major activity to perform research in the field of the nuclear fuel cycle, and therefore deals with considerable amounts of natural radionuclides of the U and Th series. The activity of the naturally occurring radionuclides U-238, Ra-226, Ra-226 and Pb-210 was determined in samples of lichen (Canoparmelia texana) and soil collected at IPEN campus. The concentrations of Ra-228, Ra-226 and Pb-210 were determined by measuring alpha and beta gross counting in a gas flow proportional detector; U and Th were determined by neutron activation analysis. The values obtained varied from 164 Bq/kg to 864 Bq/kg, 13 Bq/kg to 50 Bq/kg, and from 287 Bq/kg to 730 Bq/kg for Ra-228, Ra-226 and Pb-210 respectively. For natural U and Th the values obtained varied from 1.2 Bq/kg to 162 Bq/kg and 1.84 Bq/kg to 5.17 Bq/kg respectively. The results obtained so far suggest that the Canoparmelia texana can be used as radionuclide monitor in the vicinity of nuclear installations.

  14. The use of lichen (Canoparmelia texana) as biomonitor of atmospheric deposition of natural radionuclides from U-238 and Th-232 series

    SciTech Connect

    Leonardo, Lucio; Damatto, Sandra Regina; Mazzilli, Barbara Paci; Saiki, Mitiko

    2008-08-07

    Lichens have been used in studies of environmental pollution monitoring of various air pollutants, especially heavy metals. This paper aims to study the possibility of using this specimen for the assessment of radionuclides deposition in the vicinity of a nuclear research institute, Instituto de Pesquisas Energeticas e Nucleares (IPEN) located in Sao Paulo, Brazil. This Institute has as major activity to perform research in the field of the nuclear fuel cycle, and therefore deals with considerable amounts of natural radionuclides of the U and Th series. The activity of the naturally occurring radionuclides U-238, Ra-226, Ra-226 and Pb-210 was determined in samples of lichen (Canoparmelia texana) and soil collected at IPEN campus. The concentrations of Ra-228, Ra-226 and Pb-210 were determined by measuring alpha and beta gross counting in a gas flow proportional detector; U and Th were determined by neutron activation analysis. The values obtained varied from 164 Bq/kg to 864 Bq/kg, 13 Bq/kg to 50 Bq/kg, and from 287 Bq/kg to 730 Bq/kg for Ra-228, Ra-226 and Pb-210 respectively. For natural U and Th the values obtained varied from 1.2 Bq/kg to 162 Bq/kg and 1.84 Bq/kg to 5.17 Bq/kg respectively. The results obtained so far suggest that the Canoparmelia texana can be used as radionuclide monitor in the vicinity of nuclear installations.

  15. Production cross-sections of long-lived radionuclides in deuteron-induced reactions on natural zinc up to 23 MeV

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Haba, Hiromitsu; Murakami, Masashi; Otuka, Naohiko

    2015-03-01

    Production cross-sections of long-lived radionuclides 66,67Ga, 64,67Cu, 65,69mZn, and 58m+gCo via a deuteron irradiation on a natural zinc target were measured up to 23 MeV using a stacked-foil activation technique combined with HPGe γ-ray spectrometry. The present results showed partial agreements with the earlier experimental cross-sections and also with the theoretical data extracted from the TENDL-2013 library. Physical thick target yields of the investigated radionuclides were deduced using the measured cross-sections, and they found agreements with the directly measured ones in the literatures except for those reported by Dmitriev et al. for 65Zn. Optimal production pathways of the medically important 67Ga radionuclide using a low energy cyclotron are discussed.

  16. Framework for bringing realistic virtual natural environments to distributed simulations

    NASA Astrophysics Data System (ADS)

    Whitney, David A.; Reynolds, Robert A.; Olson, Stephen H.; Sherer, Dana Z.; Driscoll, Mavis L.; Watman, K. L.

    1997-06-01

    One of the major new technical challenges for distributed simulations is the distribution and presentation and distribution of the natural atmosphere-ocean-space environment. The natural terrain environment has been a part of such simulations for a while, but the integration of atmosphere and ocean data and effects is quite new. The DARPA synthetic environments (SE) program has been developing and demonstrating advanced technologies for providing tactically significant atmosphere-ocean data and effects for a range of simulations. A general-purpose data collection, assimilation, management, and distribution system is being developed by the TAOS (Total Atmosphere-Ocean System) Project. This system is designed to support the new high level architecture (HLA)/run- time infrastructure (RTI) being developed by the Defense Modeling and Simulation Office (DMSO), as well as existing distributed interactive simulation (DIS) network protocols. This paper describes how synthetic natural environments are being integrated by TAOS to provide an increasingly rich dynamic synthetic natural environment. Architectural designs and implementations to accommodate a range of simulation applications are discussed. A number of enabling technologies are employed, such as the development of standards for gridded data distribution, and the inclusion of derived products and local environmental features within 4-dimensional data grids. The application of TAOS for training, analysis, and engineering simulations for sensor analysis is discussed.

  17. Investigation of Depth Distribution of Radionuclides in Soil Contaminated by the Fukushima Dai-ichi Nuclear Power Plant Accident

    NASA Astrophysics Data System (ADS)

    Sato, Haruo; Niizato, Tadafumi; Tanaka, Shingo; Abe, Hironobu; Aoki, Kazuhiro

    2014-05-01

    This work was conducted as one of the researches relating to distribution maps of radiation dose rate etc. which the government has promoted as one of the counter-measures to the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011, and the 2nd investigation on the depth distribution of radionuclides (RNs) in soil was conducted after about 1 year from the accident, succeedingly to the 1st investigation which was conducted after about 3 months from the accident. Soil core samples to about 50cm deep were taken at 11 locations in Nihonmatsu-city, Kawamata-town and Namie-town. Sorption-desorption experiments of Cs-137 and I-131, CEC and AEC measurements and mineralogical analyses by XRD were conducted for 3 types of soils (sandy, clayey, organic) and those elutriated components (clay, silt, sand). Radiocaesium (Cs-134 and Cs-137) and Ag-110m were detected at all locations investigated and only at locations where radiation dose rate is high, respectively. Radiocaesium more than 95% and 99% of the inventory distributed within 5cm and 10cm deep in soil in the surface layer (mainly sandy soil), respectively, and distributed within 16cm and 20cm deep in organic soil and soil at locations where are supposed to have been used as farmland, respectively. Radiocaesium tended to extend to deeper parts in soil that organic and clayey soils are the support layer, particularly in organic soil, compared with the 1st investigation. Distribution coefficients of Cs-137 onto organic soil and its elutriated components were also lower than that onto other soils. This is consistent with trend of penetration profile.

  18. Natural and active chemical remediation of toxic metals, organics, and radionuclides in the aquatic environment

    SciTech Connect

    McPherson, G.; Pintauro, P.; O`Connor, S.

    1996-05-02

    This project focuses on the chemical aspects of remediation, with the underlying theme that chemical remediation does occur naturally. Included are studies on the fate of heavy metal and organic contaminants discharged into aquatic environments; accurate assay metal contaminants partitioned into soils, water and tissue; development of novel polymeric membranes and microporous solids for the entrapment of heavy metals; and the development of hybrid chemo-enzymatic oxidative schemes for aromatics decontamination. 49 refs.

  19. [Accumulation and distribution of 137Cs and 90Sr radionuclides in the components of water-bottom sediments-macrophytes of Lake Malye Kirpichiky].

    PubMed

    Kablova, K V; Deryagin, V V; Levina, S G; Sutyagin, A A

    2014-01-01

    This research work is devoted to analyzing the processes of accumulation and distribution of long-lived radionuclides of 90Sr and 137Cs in the components of water-sediment-macrophytes of Lake Malye Kirpichiky (Chelyabinsk region). The characteristic features of redistribution of radioactive substances, depending on the texture of the bottom sediments of the lake and the species composition of aquatic vegetation are shown. Also shown is the total stock of radionuclides in water and bottom sediments. The coefficients of 90Sr and 137Cs accumulation in bottom sediments and macrophytes have been calculated. PMID:25980292

  20. Partitioning of naturally-occurring radionuclides (NORM) in Marcellus Shale produced fluids influenced by chemical matrix.

    PubMed

    Nelson, Andrew W; Johns, Adam J; Eitrheim, Eric S; Knight, Andrew W; Basile, Madeline; Bettis, E Arthur; Schultz, Michael K; Forbes, Tori Z

    2016-04-01

    Naturally-occurring radioactive materials (NORM) associated with unconventional drilling produced fluids from the Marcellus Shale have raised environmental concerns. However, few investigations into the fundamental chemistry of NORM in Marcellus Shale produced fluids have been performed. Thus, we performed radiochemical experiments with Marcellus Shale produced fluids to understand the partitioning behavior of major radioelements of environmental health concern (uranium (U), thorium (Th), radium (Ra), lead (Pb), and polonium (Po)). We applied a novel radiotracer, (203)Pb, to understand the behavior of trace-levels of (210)Pb in these fluids. Ultrafiltration experiments indicated U, Th, and Po are particle reactive in Marcellus Shale produced fluids and Ra and Pb are soluble. Sediment partitioning experiments revealed that >99% of Ra does not adsorb to sediments in the presence of Marcellus Shale produced fluids. Further experiments indicated that although Ra adsorption is related to ionic strength, the concentrations of heavier alkaline earth metals (Ba, Sr) are stronger predictors of Ra solubility. PMID:26952871

  1. Radiological risk assessment of natural radionuclides in sand collected from some beaches along the coastline of southwestern Nigeria.

    PubMed

    Ademola, J A; Nwafor, C O

    2013-10-01

    The activity concentrations of natural radionuclides in sand from three beaches in southwestern Nigeria had been determined employing the gamma-ray spectroscopy method. The mean activity concentrations of (226)Ra, (232)Th and (40)K, respectively, were 12.5 ± 3.3, 25.8 ± 4.7 and 153.9 ± 18.5 Bq kg(-1) for Suntan Beach, 13.1 ± 3.1, 23.9 ± 4.5 and 219.9 ± 33.9 Bq kg(-1) for Bar Beach. Lekki Beach had 13.2 ± 3.2, 26.3 ± 3.8 and 149.0 ± 19.8 Bq kg(-1), respectively. The absorbed dose rates were calculated as 27.8 ± 3.1, 29.7 ± 4.0, 28.2 ± 3.3 nGy h(-1), respectively. The corresponding annual effective doses are 0.034 ± 0.004, 0.036 ± 0.005, 0.035 ± 0.004 mSv y(-1), which are less than the limit of 1 mSv y(-1) recommended for the members of the public. The radiological hazard indices are within the maximum recommended limits, hence pose no significant radiological hazards for construction. PMID:23567195

  2. Natural radionuclides content and associated dose rates in fine-grained sediments from Patras-Rion sub-basins, Greece.

    PubMed

    Papaefthymiou, H V; Chourdakis, G; Vakalas, J

    2011-01-01

    The activity concentrations of the natural radionuclides (238)U, (226)Ra, (232)Th and (40)K were measured in soil samples collected from the Patras-Rion sub-basins (Southern Greece) and were found to be 28, 27, 30 and 483 Bq kg(-1), respectively. These values compare well with the average Greek and worldwide values for crustal soil and sedimentary rocks. The mean (226)Ra/(238)U activity ratio was close to 1, implying secular radioactive equilibrium in the uranium series. All soil samples have Ra(eq) values lower than the limit of 370 Bq kg(-1), indicating their safe use in brick production. The average annual terrestrial absorbed dose rate in air was 51±14 nGy h(-1), and the average annual effective dose 0.06±0.02 mSv y(-1), which is consistent with the average worldwide exposure to external terrestrial radiation outdoors (0.07 mSv y(-1)). Non-significant differences between soils with different age and depositional environments were found, which could be attributed to a common source of sediments. PMID:21059742

  3. Fallout plutonium and natural radionuclides in annual bands of the coral Montastrea annularis, St. Croix, U. S. Virgin Islands

    SciTech Connect

    Benninger, L.K.; Dodge, R.E.

    1986-12-01

    The authors have investigated the banded coral Montastrea annularis as a recorder of the history of fallout Pu in surface seawater. To aid the Pu interpretation Ca, Mg, Sr, Na and natural radionuclides (/sup 238/U, /sup 228/Ra, /sup 232/Th and /sup 210/Pb) were also determined in the annual bands. In small samples (0.5 g) Ca, Mg and Na show correlated variations which could be due to seasonal variability in uptake. The /sup 238/U and /sup 228/Ra records were generally consistent with uptake, at constant discrimination, from surface-water reservoirs of nearly constant concentration, although one sample showed probable diagenetic addition of U. /sup 232/Th was not detected with certainty; this implies that terrigenous particles were not consistently entrapped within the coral skeleton. Interpretation of /sup 210/Pb was difficult because /sup 226/Ra was not measured. Montastrea annularis preserves a record of fallout Pu. To make this record useful it must be considered in the broadest possible geochemical context.

  4. Sediment accumulation rates in Conowingo Reservoir as determined by man-made and natural radionuclides

    SciTech Connect

    McLean, R.I.; Domotor, S.L. ); Summers, J.K.; Wilson, H. ); Olsen, C.R.; Larsen, I.L. )

    1991-05-01

    The Susquehanna River is the major contributor to sediment loadings in the Chesapeake Bay. Because many environmental contaminants are associated with suspended particulates, the degree of particle retention within the reservoirs of the lower Susquehanna River is an important consideration in evaluating contaminant loadings to the Chesapeake Bay. Profiles of weapons-test Cs-137, nuclear power plant-related Cs-134 and Cs-137, and naturally-derived Pb-210 were used to estimate rates of sediment accretion in the Conowingo Reservoir,an impoundmment of the Susquehanna River along the Maryland-Pennsylvania border. Net accretion rates ranged from about 2 cm yr{sup {minus}1} downstream of a nuclear power plant cooling discharge to a high of about 7 cm yr{sup {minus}1} at the mount of an incoming creek. Slight, but consistent, increases in the annual rate of accretion since the creation of the reservoir in 1928 are apparent. The current net average annual sediment load retained by the reservoir is estimated to be 0.4 {times} 10{sup 6} to 1.5 {times} 10{sup 6} metric tons yr{sup {minus}1}. The retained sediment load represents about 8-23% of the long-time average sediment input to the reservoir.

  5. Measurements of natural radionuclides in human teeth and animal bones as markers of radiation exposure from soil in the Northern Malaysian Peninsula

    NASA Astrophysics Data System (ADS)

    Almayahi, B. A.; Tajuddin, A. A.; Jaafar, M. S.

    2014-04-01

    This study aimed to estimate the radioactive accumulation of the radionuclides 40K, 137Cs, 210Pb, 226Ra, 228Ra, and 228Th in extracted human teeth, animal bones, and soil. The natural radionuclides were measured by high-purity germanium spectroscopy in extracted human teeth and animal bones from people and animals living in different states in the Northern Malaysian Peninsula. The average 40K, 137Cs, 210Pb, 226Ra, 228Ra, and 228Th concentrations in teeth were found to be 12.31±7.27 Bq g-1, 0.48±0.21 Bq g-1, 0.56±0.21 Bq g-1, 0.55±0.23 Bq g-1, 1.82±1.28 Bq g-1, and 0.50±0.14 Bq g-1, respectively. The corresponding concentrations in bones were found to be 3.79±0.81 Bq g-1, 0.07±0.02 Bq g-1, 0.08±0.02 Bq g-1, 0.16±0.04 Bq g-1, 0.51±1.08 Bq g-1, and 0.06±0.02 Bq g-1, respectively. The corresponding radionuclide concentrations in teeth from smokers were higher than those in non-smokers, and the corresponding radionuclide concentrations were higher in female teeth than in male teeth. The corresponding radionuclide concentrations were higher in teeth than in bones. A positive correlation was found between radionuclides in both teeth and bone samples.

  6. Do organic matter matter? Contribution of organic matter on scavenging and fractionation of natural radionuclides in the Oceanic Flux Program (OFP) site of Bermuda

    NASA Astrophysics Data System (ADS)

    Chuang, C.; Santschi, P. H.; Conte, M. H.; Schumann, D.; Ayranov, M.

    2012-12-01

    Natural particle-reactive radionuclides, 234Th, 233Pa, 210Po, 210Pb and 7Be, have been used for estimating particulate organic carbon (POC) export flux in the ocean for decades. However, by simply relying on empirically determined isotope ratios to POC and other parameters, sometimes results from field studies are puzzling and become controversial (e.g., one is summarized in Li, 2005). The picture becomes clearer when it was noticed that a missing fraction, e.g., natural organic matter, could be the cause. For example, a series of field and lab studies demonstrated that biopolymers excreted by marine micro-organisms are likely carrier molecules for a number of these isotopes (e.g., Guo et al., 2002; Quigley et al., 2002; Santschi et al., 2003; Roberts et al., 2009; Hung et al., 2010; Xu et al., 2011; Hung et al., 2012; Yang et al., 2012). To examine the effect of organic composition of the particle on the scavenging and fractionation of selected natural radionuclides (e.g., Th, Pa, Pb, Po, Be), organic composition (e.g., protein, polysaccharides, uronic acid, siderophore and amino acid contents, and etc.) and particle-water partition coefficients (Kd) were determined for sediment trap material collected in the Oceanic Flux Program (OFP) site of Bermuda (500, 1500 and 3200 m). Results showed that different organic components contribute differently to the fractionation of different radionuclides from the three depths. We conclude that natural organic matter control on the particle-water partition coefficients cannot be ignored.

  7. Vertical and horizontal distribution of radionuclides (232Th, 238U and 40K) in sediment from Manjung coastal water area Perak, Malaysia

    NASA Astrophysics Data System (ADS)

    Abdullah, Anisa; Hamzah, Zaini; Saat, Ahmad; Wood, Ab. Khalik

    2016-01-01

    Distribution of radionuclides from anthropogenic activities has been widely studied in marine coastal area. Due to rapid population growth and socio-economic development in Manjung area such as coal fired power plant, iron foundries, port development, waste discharged from factories and agriculture runoff may contribute to increase in pollution rate. The radioactive materials from anthropogenic activities could deteriorate the quality of the marine ecosystem and thus lead to possible radiological health risk to the population. Radionuclides (232Th, 238U and 40K) content in surface and profile sediment from Manjung coastal area was determined in this study. Radionuclides in sediment from seven locations were collected using sediment core sampling and measurements were carried out using Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy. The results show that the concentration of radionuclides in surface sediment and distribution trend of depth vertical profile sediment generally varies depending on locations. Enrichment factors (EF), geo-accumulation index (Igeo) and pollution index (PI) were applied to determine level of pollution of this study area. The radiological risks related to human exposure were evaluated based on external hazard index (Hex).

  8. Bioaccumulation of the artificial Cs-137 and the natural radionuclides Th-234, Ra-226, and K-40 in the fruit bodies of Basidiomycetes in Greece.

    PubMed

    Kioupi, Vasiliki; Florou, Heleny; Kapsanaki-Gotsi, Evangelia; Gonou-Zagou, Zacharoula

    2016-01-01

    The bioaccumulation of artificial Cs-137 and natural radionuclides Th-234, Ra-226, and K-40 by Basidiomycetes of several species is studied and evaluated in relation to their substratum soils. For this reason, 32 fungal samples, representing 30 species of Basidiomycetes, were collected along with their substratum soil samples, from six selected sampling areas in Greece. The fungal fruit bodies and the soil samples were properly treated and the activity concentrations of the studied radionuclides were measured by gamma spectroscopy. The measured radioactivity levels ranged as follows: Cs-137 from <0.1 to 87.2 ± 0.4 Bq kg(-1) fresh weight (F.W.), Th-234 from <0.5 ± 0.9 to 28.3 ± 25.5 Bq kg(-1) F.W., Ra-226 from <0.3 to 1.0 ± 0.5 Bq kg(-1) F.W., and K-40 from 56.4 ± 3.0 to 759.0 ± 28.3 Bq kg(-1) F.W. The analysis of the results supported that the bioaccumulation of the studied natural radionuclides and Cs-137 is dependent on the species and the functional group of the fungi. Fungi were found to accumulate Th-234 and not U-238. What is more, potential bioindicators for each radionuclide among the 32 species studied could be suggested for each habitat, based on their estimated concentration ratios (CRs). The calculation of the CRs' mean values for each radionuclide revealed a rank in decreasing order for all the species studied. PMID:26330322

  9. Aged Nuclear Explosive Melt Glass: Radiography and Scanning Electron Microscope Analyses Documenting Both Radionuclide Distribution and Glass Alteration

    SciTech Connect

    Eaton, G.F.; Smith, D.K.

    2000-03-28

    Assessment of the long-term performance of nuclear melt glass under saturated conditions provides insight into factors controlling radionuclide release into groundwater. Melt glass samples were collected from an underground nuclear detonation cavity at the Nevada Test Site that was in contact with groundwater for more than 10 years. The samples were made into thin sections and the distribution of alpha activity mapped using CR-39 plastic detectors. The melt glass is visually heterogeneous and the results of the alpha track radiography indicate that the highest alpha activity is associated with areas of dark colored glass. Analyses of the thin sections by alpha spectrometry show the prominent actinide species to be {sup 238}Pu, {sup 239}Pu and {sup 241}Am. Scanning electron microprobe analysis of the bulk glass shows conspicuous alteration layers lining internal vesicle surfaces in the glass. X-ray diffraction patterns for the alteration phases are consistent with clay mineral compositions. Glass dissolution models indicate these layers are too thick to have formed at ambient temperatures over the 10 year period in which they remained in a saturated environment. This implies the alteration layers likely formed at temperatures higher than ambient during cooling of the cavity following the underground detonation. Mobilization of this clay alteration layer as colloidal particles in groundwater represents a potential source of actinide release into the environment.

  10. Concentration and distribution of heavy metals and radionuclides in topsoils from Middle Jiu Valley surface coal exploitations sourrounding area (Gorj County, Romania)

    NASA Astrophysics Data System (ADS)

    Corneanu, Mihaela; Corneanu, Gabriel; Lacatusu, Anca-Rovena; Cojocaru, Luminita; Butnariu, Monica

    2013-04-01

    Middle Jiu Valley is one of the largest surface coal exploitation area in Romania. The coal exploitation area is a dense populated one, along the valleys are villages and the inhabitants produce for their own consumption fruits and vegetables, in their personal gardens, or cereals in the fields, nearby the villages. There was considered to be of great interest to investigate the heavy metals and radionuclides content in gardens and cropfield soils from the villages sourrounding the Thermo Electric Power Plants (TEPP) and coal surface exploitation, as well as in crude /cultivated sterile soil or ash. The topsoil samples (104) were harvested from population gardens (58), cropfields sourronding Thermo Electric Power Plants (24), crude sterile dumps (7), cultivated sterile dumps (9) and ash dumps (6). The content in radionuclides in soil was performed by Duggan (1988) method. Radionuclide activity was expressed in Bqkg-1, confidence level 95%. The total content of heavy metals in soil (Zn, Cu, Fe, Mn, Pb, Cd, Ni, Cr, Co) was measured with flame atomic mass spectrometry. The content in heavy metals was expressed in mgkg-1. Soil analysis revealed the presence of natural radionuclides, beloging from ash and coal dust, as well as of Cs-137, of Cernobal provenance. In the cropfields radionuclides content in topsoil is lower than in gardens, due to the deepper soil mobilisation. Radionuclides content over the normal limits for Romania were registered for Th-234, Pb-210, U-235 and in few locations for Ra-226. The soil content for all analysed metals was over the normal limits in most samples, in few cases with values close to allert limits. Concentrations between allert and intervention limits were registered in samples collected from 15-20 km North of TEPP Turceni, in population gardens.

  11. Determination and mapping the spatial distribution of radioactivity of natural spring water in the Eastern Black Sea Region by using artificial neural network method.

    PubMed

    Yeşilkanat, Cafer Mert; Kobya, Yaşar

    2015-09-01

    In this study, radiological distribution of gross alpha, gross beta, (226)Ra, (232)Th, (40)K, and (137)Cs for a total of 40 natural spring water samples obtained from seven cities of the Eastern Black Sea Region was determined by artificial neural network (ANN) method. In the ANN method employed, the backpropagation algorithm, which estimates the backpropagation of the errors and results, was used. In the structure of ANN, five input parameters (latitude, longitude, altitude, major soil groups, and rainfall) were used for natural radionuclides and four input parameters (latitude, longitude, altitude, and rainfall) were used for artificial radionuclides, respectively. In addition, 75 % of the total data were used as the data of training and 25 % of them were used as test data in order to reveal the structure of each radionuclide. It has been seen that the results obtained explain the radiographic structure of the region very well. Spatial interpolation maps covering the whole region were created for each radionuclide including spots not measured by using these results. It has been determined that artificial neural network method can be used for mapping the spatial distribution of radioactivity with this study, which is conducted for the first time for the Black Sea Region. PMID:26307690

  12. The influence of natural organic matter on radionuclide mobility under conditions relevant to cementitious disposal of radioactive wastes: A review of direct evidence

    NASA Astrophysics Data System (ADS)

    Stockdale, Anthony; Bryan, Nick D.

    2013-06-01

    A concept for the disposal of intermediate level radioactive wastes involves emplacement within a geological disposal facility, followed by backfilling of the facility with cement. When the closed facility is re-saturated with groundwater, this will create a high pH environment due to dissolution of the cement minerals. Dissolved organic matter (DOM; defined here as naturally occurring organic acids and humin) will be present in the groundwater at a concentration that reflects the host rock environment and the recharge source and pathway. Interactions between DOM and radionuclides may enhance transport away from the facility and are an important consideration in safety performance assessments. This review specifically focuses on studies of DOM-radionuclide interactions at the high pH range that is expected during a repository lifetime. Whilst the vast majority of available data cover binary (DOM-radionuclide) and batch ternary systems (mineral-radionuclide-DOM), this review also covers other potentially important areas, such as reversibility kinetics and redox processes that can be mediated by DOM.

  13. Estimation of brain perfusion using Va value as initial distribution volume in radionuclide angiography with technetium-99m HMPAO

    SciTech Connect

    Kawamoto, M.; Ikegami, T.

    1994-05-01

    Matsuda reported a non-invasive, simple method for the quantitative measurements of brain perfusion using radionuclide angiography with Tc-99m. HMPAO and showed graphical analysis of the ratio of brain activity to aortic arch activity gave two parameters, which are the slope of the fitted line (Ku:unidirectional influx constant) and its intercept with the yards (Vn:initial volume of distribution). Brain perfusion index (BPI),which is a connected Ku value, showed good correlation with cerebral blood flow determined with Xe-133 SPECT. The aim of our study is to elucidate the clinical significance of another parameter, Vn value, determined inpatients with cerebral vessel disease. Eighty-nine cases were studied and classified into three groups on the basis of clinical history and images of CT and/or MR: Group A, normal, 36 cases; Group B, infarction, 44 cases; Group C, subarachnoid hemorrhage, 9 cases. The average age of each group were not different statistically (63.3, 67.4 and 59.8, respectively). The average BPI values for group B and C were significantly lower than that of group A(7.7, 6. 8 and 9.5, respectively ). On the other hand, Vn for group C(0.23) was significantly lower than that for group A(0.45); however that for group B(0.49) was not. These findings indicate that cerebral blood flow in both infarction and subarachnoid hemorrhage decrease but their circumstances near vessels differ from the aspect of initial volume of tracer distribution. This might help to understand or diagnose cerebral vessel diseases.

  14. Antibodies labeled with metallic radionuclides: influence of nuclide chemistry on dose distribution.

    PubMed

    Vaughan, A T; Yankuba, S C; Anderson, P

    1987-01-01

    An antibody with human CEA specificity has been labeled with either yttrium-90, scandium-47, or indium-111, via a diethylenetriamine pentaacetic acid (DTPA) link covalently bound to the protein. The clearance of these proteins from the blood of mice can be described by a single exponential; the half-life decreases in the order indium-111 greater than yttrium-90 greater than scandium-47. Associated with the blood clearance is an uptake of radioactivity into the liver; scandium-47 has the highest concentration, indium-111 has the least, and yttrium-90 is intermediate. There is no correlation between these results and the equilibrium stability constants of the metals with DTPA-like ligands. The results obtained show that, in vivo, scandium-47 and yttrium-90 are more easily displaced from DTPA by other ions than is indium-111. They also show that free DTPA is able to extract yttrium-90 and scandium-47, but not indium-111, from the liver of treated animals, indicating that indium-111 is resistant to ligand exchange reactions in vivo. These data indicate that 1) the equilibrium stability constant is not a good indicator of the in vivo stability of metal-labeled proteins and 2) it is possible to manipulate the ion distribution and therefore the dose from scandium-47 and yttrium-90 after injection of the labeled proteins. PMID:3029601

  15. Natural radionuclide concentrations in granite rocks in Aswan and Central-Southern Eastern Desert, Egypt and their radiological implications.

    PubMed

    Issa, Shams A M; Uosif, M A M; Abd el-Salam, L M

    2012-07-01

    Different types of granites, used extensively in local construction, were collected from five localities in Egypt, namely: Abu Ziran (Central Eastern Desert), Gabal El Maesala (Aswan) and three areas from Wadi Allaqi, (Gabal Abu Marw, Gabal Haumor and Gabal um Shalman), in the South Eastern Desert. Granite samples were studied radiologically, petrographically and geochemically. The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in investigated samples by using gamma spectrometry [NaI (Tl) 3'×3']. The activity concentrations of (226)Ra, (232)Th and (40)K in the selected granite samples ranged from 9±0.5 to 111±7, 8±1 to 75±4 and 100±6 to 790±40 Bq kg(-1), respectively. The external hazard index (H(ex)), absorbed dose and annual effective dose rate were evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. The calculated radium equivalents were lower than the values recommended for construction materials (370 Bq kg(-1)). The excess lifetime cancer risks were also calculated. Petrographically, the granites studied are varied in the form of potash-feldspar, quartz, plagioclase, mica and hornblende. The accessory minerals are zircon, apatite and allanite. Geochemically, the chemical composition of the granite is studied especially for major oxides. They are characterized to have SiO(2), K(2)O, Na(2)O and Al(2)O(3) with depletion in CaO, MgO, TiO(2) and P(2)O(5). PMID:22147926

  16. Radionuclide trap

    DOEpatents

    McGuire, Joseph C.

    1978-01-01

    The deposition of radionuclides manganese-54, cobalt-58 and cobalt-60 from liquid sodium coolant is controlled by providing surfaces of nickel or high nickel alloys to extract the radionuclides from the liquid sodium, and by providing surfaces of tungsten, molybdenum or tantalum to prevent or retard radionuclide deposition.

  17. Modeling natural gas market volatility using GARCH with different distributions

    NASA Astrophysics Data System (ADS)

    Lv, Xiaodong; Shan, Xian

    2013-11-01

    In this paper, we model natural gas market volatility using GARCH-class models with long memory and fat-tail distributions. First, we forecast price volatilities of spot and futures prices. Our evidence shows that none of the models can consistently outperform others across different criteria of loss functions. We can obtain greater forecasting accuracy by taking the stylized fact of fat-tail distributions into account. Second, we forecast volatility of basis defined as the price differential between spot and futures. Our evidence shows that nonlinear GARCH-class models with asymmetric effects have the greatest forecasting accuracy. Finally, we investigate the source of forecasting loss of models. Our findings based on a detrending moving average indicate that GARCH models cannot capture multifractality in natural gas markets. This may be the plausible explanation for the source of model forecasting losses.

  18. Tracing the origin of suspended sediment in a large Mediterranean river by combining continuous river monitoring and measurement of artificial and natural radionuclides.

    PubMed

    Zebracki, Mathilde; Eyrolle-Boyer, Frédérique; Evrard, Olivier; Claval, David; Mourier, Brice; Gairoard, Stéphanie; Cagnat, Xavier; Antonelli, Christelle

    2015-01-01

    Delivery of suspended sediment from large rivers to marine environments has important environmental impacts on coastal zones. In France, the Rhone River (catchment area of 98,000 km(2)) is by far the main supplier of sediment to the Mediterranean Sea and its annual solid discharge is largely controlled by flood events. This study investigates the relevance of alternative and original fingerprinting techniques based on the relative abundances of a series of radionuclides measured routinely at the Rhone River outlet to quantify the relative contribution of sediment supplied by the main tributaries during floods. Floods were classified according to the relative contribution of the main subcatchments (i.e., Oceanic, Cevenol, extensive Mediterranean and generalised). Between 2000 and 2012, 221 samples of suspended sediment were collected at the outlet and were shown to be representative of all flood types that occurred during the last decade. Three geogenic radionuclides (i.e., (238)U, (232)Th and (40)K) were used as fingerprints in a multivariate mixing model in order to estimate the relative contribution of the main subcatchment sources-characterised by different lithologies-in sediment samples collected at the outlet. Results showed that total sediment supply originating from Pre-Alpine, Upstream, and Cevenol sources amounted to 10, 7 and 2.10(6)tons, respectively. These results highlight the role of Pre-Alpine tributaries as the main sediment supplier (53%) to the Rhone River during floods. Other fingerprinting approaches based on artificial radionuclide activity ratios (i.e., (137)Cs/(239+240)Pu and (238)Pu/(239+240)Pu) were tested and provided a way to quantify sediment remobilisation or the relative contributions of the southern tributaries. In the future, fingerprinting methods based on natural radionuclides should be further applied to catchments with heterogeneous lithologies. Methods based on artificial radionuclides should be further applied to catchments

  19. Distribution of fallout and environmental radionuclides in ice-free areas of King George Island (Western Antarctica)

    NASA Astrophysics Data System (ADS)

    Castillo, Alejandra; Schuller, Paulina; Dercon, Gerd; Nguyen, Minh-Long; Navas, Ana; Ramírez, Paola; López, César

    2013-04-01

    Climate change is progressing at a rate which is several times the global average in Western Antarctica. The Antarctic Peninsula region has experienced a rise of ca. 3°C for surface air temperature over the last 50 years; and 87% of 244 glaciers along the west coast of the Antarctic Peninsula have retreated in the last 50 years. Examining the impacts of climate change in Antarctic landscapes, in particular in the soils at the foot of retreating glaciers, can provide a better understanding of the future impacts of climate change on landscape dynamics (including land degradation and resulting changes in land, water and ecosystem quality) in the higher mountainous cold regions of the world. In this paper, results of an exploratory assessment of soil movement and identification of sediment sources and sediment sinks by investigating the distribution of fallout (FRN's) and environmental radionuclides (ERN's) in ice-free areas of King George Island (Western Antarctica) are discussed. This assessment has been carried in the context of an Instituto Antártico Chileno project, and supported by the IAEA Technical Cooperation, studying land degradation in the cold regions of South America. To this purpose soil profiles were sampled at depth increments at three different control sites. In addition, topsoil (0-1 cm depth) samples were collected from areas identified as potential soil sources and from others identified as sinks of sediments. The soil profiles at the control sites showed distinctive patterns in the depth distribution of the FRN's and ERN's. The 137Cs and 210Pbex activity mass concentration (Bq kg-1) were highest in the topsoil and penetration depth was less than 8 and 25 cm, respectively. The depth distribution of 226Ra and 232Th in the soil profiles was quite homogeneous and greater variation was found for 40K and 238U, possibly related to differences in the mineralogical composition of soils. Average mass activity values of 137Cs and 210Pbex at the source

  20. Estimation of annual effective dose due to natural and man-made radionuclides in the metropolitan area of the Bay of Cadiz (SW of Spain).

    PubMed

    Casas-Ruiz, M; Ligero, R A; Barbero, L

    2012-06-01

    In order to investigate the radiological hazard of naturally occurring radioactive material (NORM) and man-made (137)Cs radionuclide in the Bay of Cádiz, 149 samples of sediments have been analysed. Activity concentration in all the samples was determined using a HPGe detection system. Activity concentrations values of (226)Ra, (232)Th, (40)K and (137)Cs in the samples were 12.6±2.6 (2.5-40.6), 18.5±4.0 (2.8-73.4), 451±45 (105-1342) and 3.2±1.3 (0.2-16.0) Bq kg(-1), respectively. Outdoor external dose rate due to natural and man-made radionuclides was calculated to be 35.79±1.69 (4.71-119.16) nGy h(-1) and annual effective dose was estimated to be 43.89±2.27 (5.78-146.14) µSv y(-1). Results showed low levels of radioactivity due to NORM and man-made (137)Cs radionuclide in marine sediments recovered from the Bay of Cádiz (Spain), discarding any significant radiological risks related to human activities of the area. Furthermore, the obtained data set could be used as background levels for future research. PMID:21896553

  1. Regular patterns of Cs-137 distribution in natural conjugated elementary landscapes as a result of a balanced surface and depth water migration

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Romanov, Sergey

    2016-04-01

    Distribution of artificial radionuclides in the environment has long been used successfully for revealing migration pathways of their stable analogues. Migration of water in natural conjugated elementary landscapes characterizing the system of top-slope-resulting depression, has a specific structure and the radionuclide tracer is inevitably reflecting it by specific sorption and exchange processes. Other important issues are the concentration levels and the difference in characteristic time of chemical element dispersion. Modern biosphere has acquired its sustainable structure within a long period of time and is formed by basic macroelements allowing the water soluble portion of elements functioning as activators of chemical exchange. Water migration is controlled by gravitation, climate and relief while fixation depends upon the parameters of surfaces and chemical composition. The resulting structure depends on specificity and duration of the process. The long-term redistribution of chemical elements in terrestrial environment has led to a distinct geochemical structure of conjugated landscapes with a specific geometry of redistribution and accumulation of chemical elements. Migration of the newly born anthropogenic radionuclides followed natural pathways in biosphere. The initial deposition of the Chernobyl's radionuclides within the elementary landscape-geochemical system was even by condition of aerial deposition. But further exchange process is controlled by the strength of fixation and migration ability of the carriers. Therefore patterns of spatial distribution of artificial radionuclides in natural landscapes are considerably different as compared to those of the long-term forming the basic structure of chemical fields in biosphere. Our monitoring of Cs-137 radial and lateral distribution in the test plots characterizing natural undisturbed conjugated elementary landscapes performed in the period from 2005 until now has revealed a stable and specifically

  2. Distribution of organic carbon, selected stable elements and artificial radionuclides among dissolved, colloidal and particulate phases in the Rhône River (France): preliminary results.

    PubMed

    Eyrolle, F; Charmasson, S

    2001-01-01

    The behaviour of radionuclides discharged from nuclear facilities in the Rhône River depends on their distribution among the dissolved, colloidal and particulate phases. A large water sample was fractionated using sequential ultrafiltration. Size distributions of organic carbon, Fe, Al, Si, Ca, Mg, Cu, Zn, 137Cs, 60Co and 106Ru were obtained. Our results show that organic colloids account for 11% of the total organic carbon content. Approximately 20% of the dissolved (< 450 nm) Fe and Al are in colloidal classes. 137Cs is not significantly transferred by the colloidal phase while 25% of 60Co or 106Ru is associated with organic and inorganic colloids. PMID:11398374

  3. Characterization of calculation of in-situ retardation factors of contaminant transport using naturally-radionuclides and rock/water interaction occurring U-Series disequilibria timescales. 1997 annual progress report

    SciTech Connect

    Roback, R.; Murrel, M.; Goldstein, S.; Ku, T.L.; Luo, S.

    1997-01-01

    'The research is directed toward a quantitative assessment of contaminant transport rates in fracture-rock systems using uranium-series radionuclides. Naturally occurring uranium-and thorium-series radioactive disequilibria will provide information on the rates of adsorption-desorption and transport of radioactive contaminants as well as on fluid transport and rock dissolution in a natural setting. This study will also provide an improved characterization of preferential flow and contaminant transport at the Idaho Environmental and Engineering Lab. (INEEL) site. To a lesser extent, the study will include rocks in the unsaturated zone. The authors will produce a realistic model of radionuclide migration under unsaturated and saturated field conditions at the INEEL site, taking into account the retardation processes involved in the rock/water interaction. The major tasks are to (1) determine the natural distribution of U, Th, Pa and Ra isotopes in rock minerals. sorbed phases on the rocks, and in fluids from both saturated and unsaturated zones at the site, and (2) study rock/water interaction processes using U/Th series disequilibrium and a statistical analysis-based model for the Geologic heterogeneity plays an important role in transporting contaminants in fractured rocks. Preferential flow paths in the fractured rocks act as a major pathway for transport of radioactive contaminants in groundwaters. The weathering/dissolution of rock by groundwater also influences contaminant mobility. Thus, it is important to understand the hydrogeologic features of the site and their impact on the migration of radioactive contaminants. In this regard, quantification of the rock weathering/dissolution rate and fluid residence time from the observed decay-series disequilibria will be valuable. By mapping the spatial distribution of the residence time of groundwater in fractured rocks, the subsurface preferential flow paths (with high rock permeability and short fluid residence

  4. HYDROLOGIC AND GEOCHEMICAL CONTROLS ON THE TRANSPORT OF RADIONUCLIDES IN NATURAL UNDISTURBED ARID ENVIRONMENTS AS DETERMINED BY ACCELERATOR MASS SPECTROMETRY

    EPA Science Inventory

    We propose to identify and quantify the geochemical parameters controlling the migration of key radionuclides (36Cl, 90Sr, 93Zr, 99Tc, and 129I) in undisturbed soils of the shallow and deep vadose zone. Currently, the scientific understanding of these parameters cannot sufficient...

  5. Variations of cosmogenic radionuclide production rates along the meteorite orbits

    NASA Astrophysics Data System (ADS)

    Alexeev, V. A.; Laubenstein, M.; Povinec, P. P.; Ustinova, G. K.

    2015-08-01

    Cosmogenic radionuclides produced by galactic cosmic rays (GCR) in meteorites during their motion in space are natural detectors of the GCR intensity and variations along the meteorite orbits. On the basis of measured and calculated contents of cosmogenic radionuclides in the freshly fallen Chelyabinsk and Košice chondrites some peculiarities of generation of cosmogenic radionuclides of different half-lives in the chondrites of different orbits and dates of fall onto the Earth are demonstrated. Dependence of production rates of the radionuclides on the GCR variations in the heliosphere is analyzed. Using radionuclides with different half-lives it is possible to compare the average GCR intensity over various time periods. The measurement and theoretical analysis of cosmogenic radionuclides in consecutively fallen chondrites provide a unique information on the space-time continuum of the cosmogenic radionuclide production rates and their variations over a long time scale, which could be useful in correlative analyses of processes in the heliosphere. Some applications of cosmogenic radionuclide depth distribution in chondrites for estimation of their pre-atmospheric sizes are illustrated.

  6. A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory.

    PubMed

    Frostick, A; Bollhöfer, A; Parry, D

    2011-10-01

    Australian guidelines recommend that tailings materials from uranium (U) mining and milling be contained without any detrimental impact on the environment for at least 1000 years. Natural analogue sites are being investigated to determine if they can provide data on the rates of natural erosion processes which occur over these timescales, for input into predictive geomorphic computer models. This paper presents radionuclide, metal and stable lead (Pb) isotope data from sediment cores and surface soils in the vicinity of two mineralised areas in the Alligator Rivers Region. Surface scrapes from the natural Anomaly #2, south of the Ranger mineral lease, exhibit radiogenic (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios, and elevated U and metal concentrations typical for a near surface U anomaly. In contrast, samples taken from the Koongarra mineral lease (KML) show radionuclide activity and metal concentrations similar to natural areas elsewhere in the Alligator Rivers Region and Pb isotope ratios are closer to present day average crustal ratios (PDAC), as the orebodies at KML are covered by surficial sand. A sediment core collected from Anbangbang Billabong, downstream of KML, exhibits small variations in Pb isotope ratios that indicate that approximately 1% of the upper sediments in the sediment core may be derived from material originating from the U anomaly at Koongarra. PMID:20471726

  7. Scaling laws for the distribution of natural resources

    NASA Astrophysics Data System (ADS)

    Blenkinsop, Thomas

    2014-05-01

    If scaling laws can be established for the distribution of natural resources, they would have important economic consequences. For example, they can be used to estimate total resources, they can dictate exploration strategies, and they can also point to processes by which natural resources form. A scaling law for the spatial distribution of natural resources can be proposed as: M(r) ~ r-D where M(r) is the mass of resource within a circle of radius r. If the mass of individual occurrences of resources is unity, this law describes the Mass Dimension D of the resource, commonly analysed by the number-in-circle method. In this case D is simply interpreted as a measure of the clustering of the resource distribution. Space filling or random distributions have D = 2: lower values indicate a decrease in density with distance. If the mass of resource varies at each occurrence (as typical in nature), then M(r) ~ r-D is a general scaling law, with an exponent that is referred to here as the Mass-Radius scaling exponent. This exponent can have values greater than 2. Mass Dimensions and Mass-Radius scaling exponents have been determined in this study for Archean gold deposits in Zimbabwe, direct use of geothermal energy in Oregon, geothermal energy use in New Zealand and conventional and unconventional gas production in Pennsylvania. Mass Dimensions vary between 0.4 and 2, reflecting the variable clustering of the data sets. The highest values are from conventional gas production, while unconventional gas production and geothermal energy have lower values. In general Mass Dimensions and Mass-Radius scaling exponents are similar in any data sets. An interesting consequence is that an approximate value for the Mass-Radius scaling exponent can be given by the Mass Dimension. It is commonly hard to measure the Mass-Radius scaling exponent because accurate data for mass is difficult to obtain. The similarity of the two exponents suggests that substituting the Mass Dimension for the

  8. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetite, Bahia, Brazil

    SciTech Connect

    Pereira, Wagner de S; Kelecom, Alphonse

    2008-08-07

    The uranium mining at Caetite (Uranium Concentrate Unit--URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5x10{sup 3} {mu}Gy y{sup -1} has been used. The derived absorbed dose rate calculated for Tilapia was 2.51x10{sup 0} {mu}Gy y{sup -1}, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  9. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetité, Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    Pereira, Wagner de S.; Kelecom, Alphonse; Py Júnior, Delcy de Azevedo

    2008-08-01

    The uranium mining at Caetité (Uranium Concentrate Unit—URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5×103 μGy y-1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51×100 μGy y-1, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  10. Radionuclide Distribution Coefficients for Sediments Collected from Borehole 299-E17-21: Final Report for Subtask 1a

    SciTech Connect

    DI Kaplan; IV Kutynakov; KE Parker

    1998-10-14

    Over 360 distribution coefficients (KJ for cesium, iodine, selenium, Strontium, technetium, and uranium were measured in fiscal year 1998 using 20 sediments collected fkom borehole 299-El 7-21 on the Hanford Site as part of the Immobilized Low-Activity Waste-Performance Assessment (ILAW-PA). Additionally, the pH and cation-exchange capacity (a measure of the total quantity of cations that a sediment can adsorb) of these sediment samples were measured. The sediment samples originated from the Hanford formation (informal name). Statistical analyses, using Student's t-test and correlation were conducted with the measured values. There were no significant differences between layers 1 and 2 for the selenium, strontium, technetium, and uranium & values (statistics could not be applied to evaluate layer 3 &values). Significant differences between the cesium and iodine&values for layem 1 and 2 were observed. However, these differences were modest and would likely not warrant the added complexity of using three distinct ®ions to represent the Hanford formation in the ILAW-PA model. Generally, the &values of layer 3 were more similar to those of layer 2 than those of layer 1. Conservative and best estimates of radionuclide & values were calculated based on the results from these measurements. The best estimate was chosen to be the calculated median value; whereas the con- servative estimate was the miniium value, except for the conservative uranium&estimate that was based on the second-to-lowest value because of the presence of an unusually low value that was not consistent with other values from this borehole or previous reported values. Overall, the estimates are consistent with values used for the ILAW-PA, with some notable excep- tions. The conservative & estimates for technetium and uranium are approximately the same as those used for the ILAW-PA. The conservative ~alues for cesium, selenium, and strontium were appreciably more conservative than necessary. The

  11. Lyssavirus distribution in naturally infected bats from Germany.

    PubMed

    Schatz, J; Teifke, J P; Mettenleiter, T C; Aue, A; Stiefel, D; Müller, T; Freuling, C M

    2014-02-21

    In Germany, to date three different lyssavirus species are responsible for bat rabies in indigenous bats: the European Bat Lyssaviruses type 1 and 2 (EBLV-1, EBLV-2) and the Bokeloh Bat Lyssavirus (BBLV) for which Eptesicus serotinus, Myotis daubentonii and Myotis nattereri, respectively, are primary hosts. Lyssavirus maintenance, evolution, and epidemiology are still insufficiently explored. Moreover, the small number of bats infected, the nocturnal habits of bats and the limited experimental data still hamper attempts to understand the distribution, prevalence, and in particular transmission of the virus. In an experimental study in E. serotinus a heterogeneous dissemination of EBLV-1 in tissues was detected. However, it is not clear whether the EBLV-1 distribution is similar in naturally infected animals. In an attempt to further analyze virus dissemination and viral loads within naturally infected hosts we investigated tissues of 57 EBLV-1 positive individuals of E. serotinus from Germany by RT-qPCR and compared the results with those obtained experimentally. Additionally, tissue samples were investigated with immunohistochemistry to detect lyssavirus antigen in defined structures. While in individual animals virus RNA was present only in the brain, in the majority of E. serotinus viral RNA was found in various tissues with highest relative viral loads detected in the brain. Interestingly, viral antigen was confirmed in various tissues in the tongue including deep intralingual glands, nerves, muscle cells and lingual papillae. So, the tongue appears to be a prominent site for virus replication and possibly shedding. PMID:24440375

  12. Radionuclide Behavior in Containments.

    Energy Science and Technology Software Center (ESTSC)

    2000-02-14

    MATADOR analyzes the transport and deposition of radionuclides as vapor or aerosol through Light Water Reactor (LWR) containments during severe accidents and calculates environmental release fractions of radionuclides as a function of time. It is intended for use in system risk studies. The principal output is information on the timing and magnitude of radionuclide releases to the environment as a result of severely degraded core accidents. MATADOR considers the transport of radionuclides through the containmentmore » and their removal by natural deposition and the operation of engineered safety systems such as sprays. Input data on the source term from the primary system, the containment geometry, and thermal-hydraulic conditions are required.« less

  13. Effects of arctic temperatures on distribution and retention of the nuclear waste radionuclides 241Am, 57Co, and 137Cs in the bioindicator bivalve Macoma balthica

    USGS Publications Warehouse

    Hutchins, D.A.; Stupakoff, I.; Hook, S.; Luoma, S.N.; Fisher, N.S.

    1998-01-01

    The disposal of radioactive wastes in Arctic seas has made it important to understand the processes affecting the accumulation of radionuclides in food webs in coldwater ecosystems. We examined the effects of temperature on radionuclide assimilation and retention by the bioindicator bivalve Macoma balthica using three representative nuclear waste components, 241Am, 57Co, and 137Cs. Experiments were designed to determine the kinetics of processes that control uptake from food and water, as well as kinetic constants of loss. 137Cs was not accumulated in soft tissue from water during short exposures, and was rapidly lost from shell with no thermal dependence. No effects of temperature on 57Co assimilation or retention from food were observed. The only substantial effect of polar temperatures was that on the assimilation efficiency of 241Am from food, where 10% was assimilated at 2??C and 26% at 12??C. For all three radionuclides, body distributions were correlated with source, with most radioactivity obtained from water found in the shell and food in the soft tissues. These results suggest that in general Arctic conditions had relatively small effects on the biological processes which influence the bioaccumulation of radioactive wastes, and bivalve concentration factors may not be appreciably different between polar and temperate waters.

  14. Radionuclide and colloid transport in the Culebra Dolomite and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

    SciTech Connect

    RAMSEY, JAMES L.; BLAINE,R.; GARNER,J.W.; HELTON,JON CRAIG; JOHNSON,J.D.; SMITH,L.N.; WALLACE,M.

    2000-05-22

    The following topics related to radionuclide and colloid transport in the Culebra Dolomite in the 1996 performance assessment for the Waste Isolation Pilot Plant (WIPP) are presented: (1) mathematical description of models, (2) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, and (3) construction of complementary cumulative distribution functions (CCDFs) arising from stochastic (i.e., aleatory) uncertainty. The presented results indicate that radionuclide and colloid transport in the Culebra Dolomite does not constitute a serious threat to the effectiveness of the WIPP as a disposal facility for transuranic waste. Even when the effects of uncertain analysis inputs are taken into account, no radionuclide transport to the boundary with the accessible environment was observed; thus the associated CCDFs for comparison with the boundary line specified in the US Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194) are degenerate in the sense of having a probability of zero of exceeding a release of zero.

  15. Chernobyl nuclear accident hydrologic analysis and emergency evaluation of radionuclide distributions in the Dnieper River, Ukraine, during the 1993 summer flood

    SciTech Connect

    Voitsekhovitch, O.V.; Zheleznyak, M.J.; Onishi, Y.

    1994-06-01

    This report describes joint activities of Program 7.1.F, ``Radionuclide Transport in Water and Soil Systems,`` of the USA/Commonwealth of Independent States (CIS) Joint Coordinating Committee of Civilian Nuclear Reactor Safety to study the hydrogeochemical behavior of radionuclides released to the Pripyat and Dnieper rivers from the Chernobyl Nuclear Power Plant in Ukraine. These joint activities included rapid evaluation of radionuclide distributions in the Pripyat and Dnieper river system and field data evaluation and modeling for the 1993 summer flood to assist the Ukrainian government in their emergency response during the flood. In July-August 1993, heavy rainfall over the Pripyat River Catchment in Belarus and Ukraine caused severe flooding, significantly raising {sup 90}Sr concentrations in the river. Near the Chernobyl area, the maximum {sup 90}Sr concentration in the Pripyat River reached 20--25 PCi/L in early August; near the Pripyat River mouth, the concentration rose to 35 pCi/L. The peak {sup 90}Sr concentration in the Kiev Reservoir (a major source of drinking water for Kiev) was 12 pCi/L. Based on these measured radionuclide levels, additional modeling results and the assumption of water purification in a water treatment station, {sup 90}Sr concentrations in Kiev`s drinking water were estimated to be less than 8 pCi/L. Unlike {sup 90}Sr, {sup 137}Cs concentrations in the Pripyat River during the flood did not rise significantly to the pre-flood levels. Estimated {sup 137}Cs concentrations for the Kiev drinking water were two orders of magnitude lower than the drinking water standard of 500 pCi/L for {sup 137}Cs.

  16. Generalised extreme value distributions provide a natural hypothesis for the shape of seed mass distributions.

    PubMed

    Edwards, Will; Moles, Angela T; Chong, Caroline

    2015-01-01

    Among co-occurring species, values for functionally important plant traits span orders of magnitude, are uni-modal, and generally positively skewed. Such data are usually log-transformed "for normality" but no convincing mechanistic explanation for a log-normal expectation exists. Here we propose a hypothesis for the distribution of seed masses based on generalised extreme value distributions (GEVs), a class of probability distributions used in climatology to characterise the impact of event magnitudes and frequencies; events that impose strong directional selection on biological traits. In tests involving datasets from 34 locations across the globe, GEVs described log10 seed mass distributions as well or better than conventional normalising statistics in 79% of cases, and revealed a systematic tendency for an overabundance of small seed sizes associated with low latitudes. GEVs characterise disturbance events experienced in a location to which individual species' life histories could respond, providing a natural, biological explanation for trait expression that is lacking from all previous hypotheses attempting to describe trait distributions in multispecies assemblages. We suggest that GEVs could provide a mechanistic explanation for plant trait distributions and potentially link biology and climatology under a single paradigm. PMID:25830773

  17. Toward a theory of distributed word expert natural language parsing

    NASA Technical Reports Server (NTRS)

    Rieger, C.; Small, S.

    1981-01-01

    An approach to natural language meaning-based parsing in which the unit of linguistic knowledge is the word rather than the rewrite rule is described. In the word expert parser, knowledge about language is distributed across a population of procedural experts, each representing a word of the language, and each an expert at diagnosing that word's intended usage in context. The parser is structured around a coroutine control environment in which the generator-like word experts ask questions and exchange information in coming to collective agreement on sentence meaning. The word expert theory is advanced as a better cognitive model of human language expertise than the traditional rule-based approach. The technical discussion is organized around examples taken from the prototype LISP system which implements parts of the theory.

  18. Distribution of Cryptococcus neoformans in a natural site.

    PubMed Central

    Ruiz, A; Fromtling, R A; Bulmer, G S

    1981-01-01

    Pigeon droppings in a vacant tower were assayed for the number and size of viable cells of Cryptococcus neoformans. The dry, thinly scattered floor debris contained 2.6 x 10(6) viable cells per g--300 times more cells than were cultured from a large, compact pile of pigeon droppings (7.4 x 10(3) cells per g). Aerosols generated from floor debris containing pigeon droppings had an average of 360 viable cells in 31 liters of air; 27 of these cells (7.5%) were 1.1 to 3.3 micrometers in diameter and, therefore, capable of human lung deposition. Environmental factors which may influence the distribution, survival, and proliferation of C. neoformans in nature are discussed. PMID:7012011

  19. (The fate of nuclides in natural water systems)

    SciTech Connect

    Turekian, K.K. . Dept. of Geology and Geophysics)

    1989-01-01

    Our research at Yale on the fate of nuclides in natural water systems has three components to it: the study of the atmospheric precipitation of radionuclides and other chemical species; the study of the behavior of natural radionuclides in groundwater and hydrothermal systems; and understanding the controls on the distribution of radionuclides and stable nuclides in the marine realm. In this section a review of our progress in each of these areas is presented.

  20. 40 CFR Table W - 7 of Subpart W-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Emission Factors for Natural Gas Distribution W Table W Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Petroleum and Natural Gas... for Natural Gas Distribution Natural gas distribution Emission factor (scf/hour/component)...

  1. Comparison of long-term stability of containment systems for residues and wastes contaminated with naturally occurring radionuclides at an arid site and two humid sites

    SciTech Connect

    Winters, M.; Merry-Libby, P.; Hinchman, R.

    1985-01-01

    The long-term stability of near-surface containment systems designed for the management of radioactive wastes and residues contaminated with naturally occurring radionuclides are compared at the three different sites. The containment designs are: (1) a diked 8.9-m high mound, including a 3.2-m layered cap at a site (humid) near Lewiston, New York, (2) a 6.8-m-high mound, including a similar 3.2-m cap at a site (humid) near Oak Ridge, Tennessee, and (3) 4.8-m deep trenches with 3.0-m backfilled caps at a site (arid) near Hanford, Washington. Geological, hydrological, and biological factors affecting the long-term (1000-year) integrity of the containment systems at each site are examined, including: erosion, flooding, drought, wildfire, slope and cover failure, plant root penetration, burrowing animals, other soil-forming processes, and land-use changes. For the containment designs evaluated, releases of radon-222 at the arid site are predicted to be several orders of magnitude higher than at the two humid sites - upon initial burial and at 1000 years (after severe erosion). Transfer of wastes containing naturally occurring radionuclides from a humid to an arid environment offers little or no advantage relative to long-term stability of the containment system and has a definite disadvantage in terms of gaseous radioactive releases. 26 references, 3 figures, 4 tables.

  2. Distribution and transport of radionuclides in a boreal mire--assessing past, present and future accumulation of uranium, thorium and radium.

    PubMed

    Lidman, Fredrik; Ramebäck, Henrik; Bengtsson, Åsa; Laudon, Hjalmar

    2013-07-01

    The spatial distribution of (238)U, (226)Ra, (40)K and the daughters of (232)Th, (228)Ra and (228)Th, were measured in a small mire in northern Sweden. High activity concentrations of (238)U and (232)Th (up to 41 Bq (238)U kg(-1)) were observed in parts of the mire with a historical or current inflow of groundwater from the surrounding till soils, but the activities declined rapidly further out in the mire. Near the outlet and in the central parts of the mire the activity concentrations were low, indicating that uranium and thorium are immobilized rapidly upon their entering the peat. The (226)Ra was found to be more mobile with high activity concentrations further out into the mire (up to 24 Bq kg(-1)), although the central parts and the area near the outlet of the mire still had low activity concentrations. Based on the fluxes to and from the mire, it was estimated that approximately 60-70% of the uranium and thorium entering the mire currently is retained within it. The current accumulation rates were found to be consistent with the historical accumulation, but possibly lower. Since much of the accumulation still is concentrated to the edges of the mire and the activities are low compared to other measurements of these radionuclides in peat, there are no indications that the mire will be saturated with respect to radionuclides like uranium, thorium and radium in the foreseen future. On the contrary, normal peat growth rates for the region suggest that the average activity concentrations of the peat currently may be decreasing, since peat growth may be faster than the accumulation of radionuclides. In order to assess the total potential for accumulation of radionuclides more thoroughly it would, however, be necessary to also investigate the behaviour of other organophilic elements like aluminium, which are likely to compete for binding sites on the organic material. Measurements of the redox potential and other redox indicators demonstrate that uranium possibly

  3. Radiation-Induced Defects in Kaolinite as Tracers of Past Occurrence of Radionuclides in a Natural Analogue of High Level Nuclear Waste Repository

    NASA Astrophysics Data System (ADS)

    Allard, T.; Fourdrin, C.; Calas, G.

    2007-05-01

    Understanding the processes controlling migrations of radioelements at the Earth's surface is an important issue for the long-term safety assessment of high level nuclear waste repositories (HLNWR). Evidence of past occurrence and transfer of radionuclides can be found using radiation-induced defects in minerals. Clay minerals are particularly relevant because of their widespread occurrence at the Earth's surface and their finely divided nature which provides high contact area with radioactive fluids. Owing to its sensitivity to radiations, kaolinite can be used as natural, in situ dosimeter. Kaolinite is known to contain radiation-induced defects which are detected by Electron Paramagnetic Resonance. They are differentiated by their nature, their production kinetics and their thermal stability. One of these defects is stable at the scale of geological periods and provides a record of past radionuclide occurrence. Based on artificial irradiations, a methodology has been subsequently proposed to determine paleodose cumulated by kaolinite since its formation. The paleodose can be used to derive equivalent radioelement concentrations, provided that the age of kaolinite formation can be constrained. This allows quantitative reconstruction of past transfers of radioelements in natural systems. An example is given for the Nopal I U-deposit (Chihuahua, Mexico), hosted in hydrothermally altered volcanic tufs and considered as analogue of the Yucca Mountain site. The paleodoses experienced by kaolinites were determined from the concentration of defects and dosimetry parameters of experimental irradiations. Using few geochemical assumption, a equivalent U-content responsible for defects in kaolinite was calculated from the paleodose, a dose rate balance and model ages of kaolinites constrained by tectonic phases. In a former study, the ages were assumptions derived from regional tectonic events. In thepresent study, ages of mineralization events are measured from U

  4. Central Appalachian basin natural gas database: distribution, composition, and origin of natural gases

    USGS Publications Warehouse

    Román Colón, Yomayra A.; Ruppert, Leslie F.

    2015-01-01

    The U.S. Geological Survey (USGS) has compiled a database consisting of three worksheets of central Appalachian basin natural gas analyses and isotopic compositions from published and unpublished sources of 1,282 gas samples from Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The database includes field and reservoir names, well and State identification number, selected geologic reservoir properties, and the composition of natural gases (methane; ethane; propane; butane, iso-butane [i-butane]; normal butane [n-butane]; iso-pentane [i-pentane]; normal pentane [n-pentane]; cyclohexane, and hexanes). In the first worksheet, location and American Petroleum Institute (API) numbers from public or published sources are provided for 1,231 of the 1,282 gas samples. A second worksheet of 186 gas samples was compiled from published sources and augmented with public location information and contains carbon, hydrogen, and nitrogen isotopic measurements of natural gas. The third worksheet is a key for all abbreviations in the database. The database can be used to better constrain the stratigraphic distribution, composition, and origin of natural gas in the central Appalachian basin.

  5. Manmade and natural radionuclides in north east Atlantic shelf and slope sediments: Implications for rates of sedimentary processes and for contaminant dispersion.

    PubMed

    MacKenzie, A B; Stewart, A; Cook, G T; Mitchell, L; Ellet, D J; Griffiths, C R

    2006-10-01

    Results are presented for a study of manmade and natural radionuclides in north east Atlantic continental shelf and slope sediments to the west of Scotland. The data are interpreted in the context of sediment mixing and accumulation processes and are used to establish the westward extent of contamination of the sediment system. Offshore shelf and slope sediments were found to have post-glacial sedimentation rates of the order of 1 cm ky(-1) but nearshore sediments had much higher accumulation rates of the order of 0.1 cm y(-1). Surface mixed layer depths of up to 6 cm were observed and non-local mixing affected most of the slope sediments, resulting in advective transport of surface sediment to depths of up to 10 cm. Biodiffusion coefficients for offshore shelf and slope sediments were dominantly in the range 10(-8) to 10(-9) cm2 s(-1). The study confirmed that seawater contaminated with Sellafield waste radionuclides is dominantly entrained to the east of 7 degrees W and, consistent with this, higher levels of Sellafield derived radionuclides were confined to nearshore sediments, with lower levels to the west of 7 degrees W. 238Pu/(239,240)Pu data indicated that Sellafield contributed 75-91% of the total plutonium in coastal sediment but only about 4-8% of the total in slope sediments. By analogy, it can be concluded that a similar situation will apply to other contaminants in seawater entering the north east Atlantic via the North Channel. PMID:16757016

  6. Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012.

    PubMed

    Mikami, Satoshi; Maeyama, Takeshi; Hoshide, Yoshifumi; Sakamoto, Ryuichi; Sato, Shoji; Okuda, Naotoshi; Demongeot, Stéphanie; Gurriaran, Rodolfo; Uwamino, Yoshitomo; Kato, Hiroaki; Fujiwara, Mamoru; Sato, Tetsuro; Takemiya, Hiroshi; Saito, Kimiaki

    2015-01-01

    Spatial distributions and temporal changes of radioactive fallout released by the Fukushima Dai-ichi Nuclear Power Plant accident have been investigated by two campaigns with three measurement schedules. The inventories (activities per unit area) of the radionuclides deposited onto ground soil were measured using portable gamma-ray spectrometers at nearly 1000 locations (at most) per measurement campaign. Distribution maps of the inventories of (134)Cs, (137)Cs, and (110m)Ag as of March, September, and December 2012 were constructed. No apparent temporal change of the radionuclide inventories was observed from March to December 2012. Weathering effects (e.g., horizontal mobility) were not noticeable during this period. Spatial dependence in the ratios of (134)Cs/(137)Cs and (110m)Ag/(137)Cs were observed in the Tohoku and Kanto regions. The detailed maps of (134)Cs and (137)Cs as of September 2012 and December 2012 were constructed using the relationship between the air dose rate and the inventory. PMID:25307776

  7. Laboratory studies of radionuclide distributions between selected groundwaters and geologic media. Progress report, October 1, 1979-September 30, 1980

    SciTech Connect

    Daniels, W.R.

    1981-01-01

    During FY-1980, Los Alamos Scientific Laboratory contributions to the Waste/Rock Interactions Technology program were primarily in the areas of migration-rate studies using crushed rock, whole core, and fractured core columns; parametric studies of variables which may influence radionuclide sorption-desorption behavior; and initial studies of actinide chemistry in near-neutral solutions and Eh control. Batch experiments in both air and a controlled atmosphere (nitrogen, less than or equal to 0.2 ppM oxygen, less than or equal to 20 ppM carbon dioxide) for the sorption of several radionuclides on granite and argillite were completed. These data also provided informaton on the effects of other parameters, such as particle size and contact time. All nine elements studied had different sorption ratios for argillite when measured under the controlled atmosphere than when measured in air, except possibly for americium where any effect was smaller than the standard deviations. As expected, strontium, cesium, and barium are least affected by the presence or absence of oxygen and carbon dioxide. Columns of crushed rock and solid and cracked cores were used to study the migration of radionuclides through such materials. In general, sorption ratios measured by batch techniques are 2 to 3 times greater than those for columns; however, a wide variation in behavior was observed, depending upon the element and the mineralogy. Work has begun on a system wherein traced groundwater is circulated through a crushed rock column; this should provide a link between the usual, single-pass, crushed rock columns and the batch experiments. Materials characterization has continued, and techniques for the determination of Fe(II) in silicate rocks and groundwater have been made operational. Work on the fundamental solution chemistry of the actinides has been started.

  8. Radionuclide cisternogram

    MedlinePlus

    ... please enable JavaScript. A radionuclide cisternogram is a nuclear scan test. It is used to diagnose problems ... damage. The amount of radiation used during the nuclear scan is very small. Almost all of the ...

  9. Use of natural radionuclides to determine the time range of the accidental melting of an orphan radioactive source in a steel recycling plant.

    PubMed

    Cantaluppi, Chiara; Ceccotto, Federica; Cianchi, Aldo

    2012-02-01

    In the rare event that an orphan radioactive source is melted in an Electric Arc Furnace steel recycling plant, the radionuclides present are partitioned in the different products, by-products and waste. As a consequence of an unforeseen melting of a radiocesium source, cesium radioisotopes can be found in the dust, together with many natural radionuclides from the decay of radon and thoron, which are present in the atmosphere, picked up from the off-gas evacuation system and associated with the dust of the air filtration system ("baghouse"). In this work we verified that the activity concentration of ²¹²Pb in this dust is essentially constant in a specific factory so that it is possible to use it to date back to the time of the accidental melting of the orphan radioactive source. The main features of this method are described below, together with the application to a particular case in which this method was used for dating the moment in which the dust was contaminated with ¹³⁷Cs. PMID:22103976

  10. Mn distribution in natural sphalerites: a micronalytical and EPR study

    NASA Astrophysics Data System (ADS)

    di Benedetto, F.; Bernardini, G. P.; Cipriani, C.; Plant, D.; Romanelli, M.; Vaughan, D. J.

    2003-04-01

    Electron Paramagnetic Resonance (EPR) has been successfully applied to determine the local coordination and distribution of transition metal cations in sulphides and sulphosalts (Di Benedetto et al., 2002). Due to its enhanced sensitivity and element-specificity it is one of the best tools to monitor Mn(II) behaviour down to very low concentrations. In order to reach a fuller understanding of the spectroscopic results, a microanalytical study has also been undertaken by means of Electron Microprobe Analysis. Operating conditions were chosen to achieve the lowest possible detection limits, taking into account that Mn can replace Zn in the sphalerite lattice both as a minor and trace element, and that EPR can detect Mn(II) below the ppm range. Six natural samples from the Museo di Storia Naturale, Università di Firenze, were selected to have pure single crystals and avoid magnetically active phases associated with the sphalerite. The Mn concentration determined ranges between 30 and 14300 ppm and Mn content varies considerably within the same sample, leading to differences up to the 50% as compared to the mean value. X-ray images confirm Mn to be distributed with an unusual pattern, unrelated to the other common Zn-replacing cations, Fe and Cd, present in the samples. Powder EPR spectra reveal at least three different Mn(II) signals: two sextets, overlapping in all samples containing Mn as trace element, and a single line, present only in the more concentrated samples. While the latter have been attributed to an inhomogeneous Mn distribution, due to an enhanced Mn-Mn superexchange interaction, the difference between the two sextets, observed by means of EEPR investigations in a synthetic sphalerite (Di Benedetto et al., 2002), appears unrelated to the Mn concentration and may be attributed to small differences in the local coordination of Mn(II) ions. This, in turn, may be explained by the segregation of small amounts of Mn into polytypic domains, features which

  11. Global distribution of naturally occurring marine hypoxia on continental margins

    NASA Astrophysics Data System (ADS)

    Helly, John J.; Levin, Lisa A.

    2004-09-01

    Hypoxia in the ocean influences biogeochemical cycling of elements, the distribution of marine species and the economic well being of many coastal countries. Previous delineations of hypoxic environments focus on those in enclosed seas where hypoxia may be exacerbated by anthropogenically induced eutrophication. Permanently hypoxic water masses in the open ocean, referred to as oxygen minimum zones, impinge on a much larger seafloor surface area along continental margins of the eastern Pacific, Indian and western Atlantic Oceans. We provide the first global quantification of naturally hypoxic continental margin floor by determining upper and lower oxygen minimum zone depth boundaries from hydrographic data and computing the area between the isobaths using seafloor topography. This approach reveals that there are over one million km 2 of permanently hypoxic shelf and bathyal sea floor, where dissolved oxygen is <0.5 ml l -1; over half (59%) occurs in the northern Indian Ocean. We also document strong variation in the intensity, vertical position and thickness of the OMZ as a function of latitude in the eastern Pacific Ocean and as a function of longitude in the northern Indian Ocean. Seafloor OMZs are regions of low biodiversity and are inhospitable to most commercially valuable marine resources, but support a fascinating array of protozoan and metazoan adaptations to hypoxic conditions.

  12. Radionuclide transport in the vicinity of the repository and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

    SciTech Connect

    STOCKMAN,CHRISTINE T.; GARNER,J.W.; HELTON,JON CRAIG; JOHNSON,JAY DEAN; SHINTA,A.; SMITH,L.N.

    2000-05-22

    The following topics related to radionuclide transport in the vicinity of the repository in the 1996 performance assessment for the Waste Isolation Pilot Plant are presented (1) mathematical description of models, (2) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, (3) construction of complementary cumulative distribution functions (CCDFs) arising from stochastic (i.e., aleatory) uncertainty, and (4) uncertainty and sensitivity analysis results for CCDFs. The presented results indicate that no releases to the accessible environment take place due to radionuclide movement through the anhydrite marker beds, through the Dewey Lake Red Beds or directly to the surface, and also that the releases to the Culebra Dolomite are small. Even when the effects of uncertain analysis inputs are taken into account, the CCDFs for release to the Culebra Dolomite fall to the left of the boundary line specified in the US Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194).

  13. Hydrologic and geochemical controls on the transport of radionuclides in natural undisturbed arid environments as determined by accelerator mass spectrometry measurements

    SciTech Connect

    Nimz, G; Caffee, M W; McAninch, J

    2000-04-01

    This project developed techniques for measuring globally distributed radionuclides that occur today in extremely low abundances (''fallout'' from the era of atmospheric nuclear testing), and then applied these techniques to better understand the mechanisms by which radionuclides migrate. The techniques employ accelerator mass spectrometry (AMS), a relatively new analytical tool that permits this work to be conducted for the first time. The goal in this project was to develop AMS analytical techniques for {sup 129}I (fallout concentration: {approx} 10{sup 6} atoms/g) {sup 99}Tc ({approx} 10{sup 9} atoms/g), {sup 90}Sr ({approx}10{sup 7} atoms/gram soil), and {sup 93}Zr ({approx} 10{sup 9} atoms/g), and improved methods for {sup 36}Cl ({approx} 10{sup 9} atoms/g). As a demonstration of the analytical techniques, and as an investigation of identified problems associated with characterizing moisture and radionuclide movement in unsaturated desert soils, we developed a vadose zone research site at the Nevada Test Site. Our findings can be summarized as follows: (1) The distribution of chloride and {sup 36}Cl at the research site indicates that the widely-used ''chloride accumulation'' method for estimating moisture flux is erroneous; some mechanism for attenuation of chloride exists, violating an assumption of the accumulation method; (2) {sup 129}I is fractionated into several soil compartments that have varying migration abilities; the two most mobile can be tentatively identified as Fe/Mn oxyhydroxides and organic acids based on our sequential leaching techniques; (3) These most mobile constituents are capable of migrating at a rate greater than that of {sup 36}Cl, usually considered the most mobile solute in hydrologic systems; these constituents may be colloidal in character, of neutral surface charge, and therefore conservative in aqueous migration; (4) {sup 99}Tc is readily measurable by AMS, as we demonstrate by the first AMS {sup 99}Tc measurements of

  14. Radionuclide cisternogram

    MedlinePlus

    A radionuclide cisternogram is a nuclear scan test. It is used to diagnose problems with the flow of spinal fluid. ... a lumbar puncture include pain at the injection site, bleeding, and ... used during the nuclear scan is very small. Almost all of the ...

  15. Risk assessment due to ingestion of natural radionuclides and heavy metals in the milk samples: a case study from a proposed uranium mining area, Jharkhand.

    PubMed

    Giri, Soma; Singh, Gurdeep; Jha, V N; Tripathi, R M

    2011-04-01

    Ingestion of radionuclides and heavy metals through drinking water and food intake represents one of the important pathways for long-term health considerations. Milk and milk products are main constituents of the daily diet. Radionuclides and heavy metals can be apprehended in the ecosystem of the East Singhbhum region which is known for its viable grades of uranium, copper and other minerals. For the risk assessment studies, samples of milk were collected from twelve villages around Bagjata mining area and analysed for U(nat), 226Ra, 230Th, 210Po, Fe, Mn, Zn, Pb, Cu and Ni. Analysis of the results of the study reveals that the geometric mean of U(nat), 226Ra, 230Th and 210Po was 0.021, 0.24, 0.23 and 1.08 Bq l(-1), respectively. The ingestion dose was calculated to be 12.34 μSvY(-1) which is reflecting the natural background dose via the route of ingestion, and much below the 1 mSv limit set in the new ICRP recommendations. The excess lifetime cancer risk was estimated to be 1.72×10(-4) which is within the acceptable excess individual lifetime cancer risk value of 1×10(-4). The geometric mean of Fe, Mn, Zn, Cu and Ni was 4.91, 0.29, 4.77, 0.56 and 0.48 mgl(-1), respectively; whereas the daily intake was computed to be 0.44, 0.03, 0.43, 0.05 and 0.04 mg/day, respectively. Pb was not detected in any of the samples. The hazard quotient revealed that the intake of the heavy metals through the ingestion of milk does not pose any apparent threat to the local people as none of the HQ of the heavy metals exceeds the limit of 1. PMID:20490912

  16. Initial Radionuclide Inventories

    SciTech Connect

    Miller, H

    2005-07-12

    The purpose of this analysis is to provide an initial radionuclide inventory (in grams per waste package) and associated uncertainty distributions for use in the Total System Performance Assessment for the License Application (TSPA-LA) in support of the license application for the repository at Yucca Mountain, Nevada. This document is intended for use in postclosure analysis only. Bounding waste stream information and data were collected that capture probable limits. For commercially generated waste, this analysis considers alternative waste stream projections to bound the characteristics of wastes likely to be encountered using arrival scenarios that potentially impact the commercial spent nuclear fuel (CSNF) waste stream. For TSPA-LA, this radionuclide inventory analysis considers U.S. Department of Energy (DOE) high-level radioactive waste (DHLW) glass and two types of spent nuclear fuel (SNF): CSNF and DOE-owned (DSNF). These wastes are placed in two groups of waste packages: the CSNF waste package and the codisposal waste package (CDSP), which are designated to contain DHLW glass and DSNF, or DHLW glass only. The radionuclide inventory for naval SNF is provided separately in the classified ''Naval Nuclear Propulsion Program Technical Support Document'' for the License Application. As noted previously, the radionuclide inventory data presented here is intended only for TSPA-LA postclosure calculations. It is not applicable to preclosure safety calculations. Safe storage, transportation, and ultimate disposal of these wastes require safety analyses to support the design and licensing of repository equipment and facilities. These analyses will require radionuclide inventories to represent the radioactive source term that must be accommodated during handling, storage and disposition of these wastes. This analysis uses the best available information to identify the radionuclide inventory that is expected at the last year of last emplacement, currently identified as

  17. Initial Radionuclide Inventories

    SciTech Connect

    H. Miller

    2004-09-19

    The purpose of this analysis is to provide an initial radionuclide inventory (in grams per waste package) and associated uncertainty distributions for use in the Total System Performance Assessment for the License Application (TSPA-LA) in support of the license application for the repository at Yucca Mountain, Nevada. This document is intended for use in postclosure analysis only. Bounding waste stream information and data were collected that capture probable limits. For commercially generated waste, this analysis considers alternative waste stream projections to bound the characteristics of wastes likely to be encountered using arrival scenarios that potentially impact the commercial spent nuclear fuel (CSNF) waste stream. For TSPA-LA, this radionuclide inventory analysis considers U.S. Department of Energy (DOE) high-level radioactive waste (DHLW) glass and two types of spent nuclear fuel (SNF): CSNF and DOE-owned (DSNF). These wastes are placed in two groups of waste packages: the CSNF waste package and the codisposal waste package (CDSP), which are designated to contain DHLW glass and DSNF, or DHLW glass only. The radionuclide inventory for naval SNF is provided separately in the classified ''Naval Nuclear Propulsion Program Technical Support Document'' for the License Application. As noted previously, the radionuclide inventory data presented here is intended only for TSPA-LA postclosure calculations. It is not applicable to preclosure safety calculations. Safe storage, transportation, and ultimate disposal of these wastes require safety analyses to support the design and licensing of repository equipment and facilities. These analyses will require radionuclide inventories to represent the radioactive source term that must be accommodated during handling, storage and disposition of these wastes. This analysis uses the best available information to identify the radionuclide inventory that is expected at the last year of last emplacement, currently identified as

  18. Distribution patterns of particle-reactive radionuclides in sediments off eastern Hainan Island, China: Implications for source and transport pathways

    NASA Astrophysics Data System (ADS)

    Huang, Dekun; Du, Jinzhou; Deng, Bing; Zhang, Jing

    2013-04-01

    The study of sediment sources and transport processes from land to ocean can help in predicting the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas and/or open oceans. The activities of 7Be, excess 210Pb (210Pbxs), excess 234Th (234Thxs) and 137Cs in surface sediments collected offshore of eastern Hainan Island, China, in August of 2008 were measured by an HPGe γ-spectrometer to evaluate the sediment source and transport processes. The results showed that all the surface sediments were silt or sand, and the mean grain sizes of the northern locations were higher than those in the other regions. The ranges of activities of 7Be, 210Pbxs, 234Thxs and 137Cs in surface sediment were 0.14-12.7, 37.4-199, 2.24-176 and 0.02-1.06 Bq kg-1, with averages of 3.78±4.77, 110±8.1, 66.7±8.9 and 0.52±0.22 Bq kg-1, respectively. The activities of the radionuclides increased from coast to offshore in the northern section. The upwelling may cause high particle fluxes with high activities of 210Pbxs and 234Thxs. A comparison of the source and transport of the suspended sediments with river discharge along the coast shows that the coastal current and offshore upwelling are the dominant factors for the transport and sources of surface sediment in the study region. The sediment was transported from south to north by the coastal current, and sediments with a large grain size may be deposited via the north loop current. The ratios of the nuclide activities indicated that the suspended particles need approximately one year to be removed from the water column into the seabed and that the main source of the sediments off eastern Hainan Island in the study regions was terrigenous deposits.

  19. Physical setting and natural sources of exposure to carcinogenic trace elements and radionuclides in Lahontan Valley, Nevada.

    PubMed

    Seiler, Ralph

    2012-04-01

    In Lahontan Valley, Nevada, arsenic, cobalt, tungsten, uranium, radon, and polonium-210 are carcinogens that occur naturally in sediments and groundwater. Arsenic and cobalt are principally derived from erosion of volcanic rocks in the local mountains and tungsten and uranium are derived from erosion of granitic rocks in headwater reaches of the Carson River. Radon and 210Po originate from radioactive decay of uranium in the sediments. Arsenic, aluminum, cobalt, iron, and manganese concentrations in household dust suggest it is derived from the local soils. Excess zinc and chromium in the dust are probably derived from the vacuum cleaner used to collect the dust, or household sources such as the furnace. Some samples have more than 5 times more cobalt in the dust than in the local soil, but whether the source of the excess cobalt is anthropogenic or natural cannot be determined with the available data. Cobalt concentrations are low in groundwater, but arsenic, uranium, radon, and 210Po concentrations often exceed human-health standards, and sometime greatly exceed them. Exposure to radon and its decay products in drinking water can vary significantly depending on when during the day that the water is consumed. Although the data suggests there have been no long term changes in groundwater chemistry that corresponds to the Lahontan Valley leukemia cluster, the occurrence of the very unusual leukemia cluster in an area with numerous 210Po and arsenic contaminated wells is striking, particularly in conjunction with the exceptionally high levels of urinary tungsten in Lahontan Valley residents. Additional research is needed on potential exposure pathways involving food or inhalation, and on synergistic effects of mixtures of these natural contaminants on susceptibility to development of leukemia. PMID:21536017

  20. Linking Infants' Distributional Learning Abilities to Natural Language Acquisition

    ERIC Educational Resources Information Center

    van Heugten, Marieke; Johnson, Elizabeth K.

    2010-01-01

    This study examines the link between distributional patterns in the input and infants' acquisition of non-adjacent dependencies. In two Headturn Preference experiments, Dutch-learning 24-month-olds (but not 17-month-olds) were found to track the remote dependency between the definite article "het" and the diminutive suffix "-je" while no such…

  1. Implications of sedimentological and hydrological processes on the distribution of radionuclides in a salt marsh near Sellafield, Cumbria

    SciTech Connect

    Carr, A.P.; Blackley, M.W.L.

    1985-01-01

    The report examines sedimentological and hydrological processes affecting a salt marsh in the Ravenglass estuary, which is situated south of the Sellafield nuclear-fuel-reprocessing plant. The results are discussed in the context of the distribution of low-level radioactive effluent at the site.

  2. Representation of higher-order statistical structures in natural scenes via spatial phase distributions.

    PubMed

    MaBouDi, HaDi; Shimazaki, Hideaki; Amari, Shun-Ichi; Soltanian-Zadeh, Hamid

    2016-03-01

    Natural scenes contain richer perceptual information in their spatial phase structure than their amplitudes. Modeling phase structure of natural scenes may explain higher-order structure inherent to the natural scenes, which is neglected in most classical models of redundancy reduction. Only recently, a few models have represented images using a complex form of receptive fields (RFs) and analyze their complex responses in terms of amplitude and phase. However, these complex representation models often tacitly assume a uniform phase distribution without empirical support. The structure of spatial phase distributions of natural scenes in the form of relative contributions of paired responses of RFs in quadrature has not been explored statistically until now. Here, we investigate the spatial phase structure of natural scenes using complex forms of various Gabor-like RFs. To analyze distributions of the spatial phase responses, we constructed a mixture model that accounts for multi-modal circular distributions, and the EM algorithm for estimation of the model parameters. Based on the likelihood, we report presence of both uniform and structured bimodal phase distributions in natural scenes. The latter bimodal distributions were symmetric with two peaks separated by about 180°. Thus, the redundancy in the natural scenes can be further removed by using the bimodal phase distributions obtained from these RFs in the complex representation models. These results predict that both phase invariant and phase sensitive complex cells are required to represent the regularities of natural scenes in visual systems. PMID:26278166

  3. Spatial distributions of local illumination color in natural scenes.

    PubMed

    Nascimento, Sérgio M C; Amano, Kinjiro; Foster, David H

    2016-03-01

    In natural complex environments, the elevation of the sun and the presence of occluding objects and mutual reflections cause variations in the spectral composition of the local illumination across time and location. Unlike the changes in time and their consequences for color appearance and constancy, the spatial variations of local illumination color in natural scenes have received relatively little attention. The aim of the present work was to characterize these spatial variations by spectral imaging. Hyperspectral radiance images were obtained from 30 rural and urban scenes in which neutral probe spheres were embedded. The spectra of the local illumination at 17 sample points on each sphere in each scene were extracted and a total of 1904 chromaticity coordinates and correlated color temperatures (CCTs) derived. Maximum differences in chromaticities over spheres and over scenes were similar. When data were pooled over scenes, CCTs ranged from 3000 K to 20,000 K, a variation of the same order of magnitude as that occurring over the day. Any mechanisms that underlie stable surface color perception in natural scenes need to accommodate these large spatial variations in local illumination color. PMID:26291072

  4. Distribution and nature of UV absorbers on Triton's surface

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1995-01-01

    Substantial evidence suggests that a UV spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAMs exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SaM material. We hope to determine if UV-SAMs on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAMs has been determined, further constraints on their composition cable made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

  5. Distribution and nature of UV absorbers on Triton's surface

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1994-01-01

    Substantial evidence suggests that a UV Spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAM's exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SAM material. We hope to determine if UV-SAM's on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAM's has been determined, further constraints on their composition can be made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on Voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

  6. Distribution and nature of UV absorbers on Trition's surface

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1995-01-01

    Substantial evidence suggests that a UV (ultraviolet) Spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAM's exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SAM material. We hope to determine if UV-SAM's on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAM's has been determined, further constraints on their composition can be made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on Voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

  7. Specific activity of natural and anthropogenic radionuclides and radiological hazard assessment in surface soil samples collected along the Andaman sea coast in southern region of Thailand

    NASA Astrophysics Data System (ADS)

    Kessaratikoon, P.; Boonkrongcheep, R.; Benjakul, S.; Udomsomporn, S.

    2015-05-01

    The specific activities of natural (40K, 226Ra and 232Th) and anthropogenic radionuclides (137Cs) in 314 surface soil samples collected from three provinces (Phuket, Phang-Nga and Krabi) along the Andaman sea coast in southern region of Thailand were studied and evaluated. Experimental results were obtained by using a high-purity germanium (HPGe) detector and gamma spectrometry analysis system. It was found that the mean values of specific activities of 40K, 226Ra, 232Th and 137Cs were 2859.63 ± 209.83, 157.10 ± 8.06, 137.16 ± 7.26 and 4.88 ± 2.34 Bq/kg, respectively. Furthermore, four radiological hazard indices which are absorbed dose rate in air (D), radium equivalent activity (Raeq), external hazard index (Hex) and annual effective dose rate (AEDout) in the area under consideration were also calculated and came out to be 277.11 ± 16.96 nGy/h, 575.16 ± 34.67 Bq/kg, 1.55 ± 0.09 and 0.34 ± 0.02 mSv/y, respectively. The experimental results were also compared and found to be comparable with national and global radioactivity measurements and evaluations. Moreover, the radioactive contour maps of the investigated area were also created and presented in this paper.

  8. Distribution patters of mobile mud in the East China Sea: elucidated from particle size, radionuclides and magnetic analysis

    NASA Astrophysics Data System (ADS)

    Wang, J.; Du, J.; Zhang, W.; Zhang, J.

    2013-12-01

    Submarine surface sediments due to resuspension may return to water column followed by particles sedimentation on the seabed. Therefore, particulate material in estuarine and coastal environments would be typically deposited and resuspended several times before permanent accumulation or transport offshore. The suspension and mobile sediments, referred to be "mobile mud" definated by high water content(≥0.30) and no-decay 210Pbex vertical distribution, play an important role in the biogeochemical cycles in the estuarine/coastal area. In the present work, the spatial and temporal distribution of thickness, grain-size in the mobile mud of the East China Sea were conducted by May and August, 2011. Most mobile mud are distributed along the coast and north offshore, and the thick mud layer (≥2cm) is featured with fine grain size, high water content and TOC, exhibiting the activeness of mobile mud. The total amount of mobile mud in the East China Sea is ten times in comparison with annual sediment discharge from the Changjiang River. The maximum of mobile mud thickness and 7Be activity in May was distributed in the south coast, but that in August was distributed in the north coast. The mobile mud HIRM was relatively large both in May and August, but the north coast HIRM in August was larger than that in May. All these change of mobile mud thickness, nuclides and magnetic properties indicated that the mobile mud formation mechanism has the different patterns in the different region.The north coastal mobile mud formation is dominated by the Changjiang Diluted Water, and in the south is controlled by the monsoon-influenced Zhejiang-Fujian coastal current. The main source of mobile mud near the inshore is predominantly input from the Changjiang River. However, most mobile mud in the north offshore may be originally derived from the Changjiang River and old Huanghe River. Compared south offshore with thin layer of mobile mud, the north offshore mobile mud formation

  9. Dynamics and distribution of natural and human-caused hypoxia

    NASA Astrophysics Data System (ADS)

    Rabalais, N. N.; Díaz, R. J.; Levin, L. A.; Turner, R. E.; Gilbert, D.; Zhang, J.

    2010-02-01

    Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen re-aeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (<2 mg L-1, or approximately 30% saturation) can form, therefore, under "natural" conditions, and are more likely to occur in marine systems when the water residence time is extended, water exchange and ventilation are minimal, stratification occurs, and where carbon production and export to the bottom layer are relatively high. Hypoxia has occurred through geological time and naturally occurs in oxygen minimum zones, deep basins, eastern boundary upwelling systems, and fjords. Hypoxia development and continuation in many areas of the world's coastal ocean is accelerated by human activities, especially where nutrient loading increased in the Anthropocene. This higher loading set in motion a cascading set of events related to eutrophication. The formation of hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed. Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of strengthened stratification alone, from increased

  10. Distribution and environmental impacts of some radionuclides in sedimentary rocks at Wadi Naseib area, southwest Sinai, Egypt.

    PubMed

    El Galy, M M; El Mezayn, A M; Said, A F; El Mowafy, A A; Mohamed, M S

    2008-07-01

    The present study examines the natural radioactivity in some sedimentary rocks and their associated environmental impacts at Wadi Naseib area. Exposure rate (ER), dose rate (DR), radium equivalent activity (Ra(eq)), external hazard index (H(ex)), internal hazard index (H(in)) and radioactivity level index (I(gamma)) were calculated. Wadi Naseib area is covered with sedimentary rocks of early to late Paleozoic age. These rocks are classified into two types: mineralized and non-mineralized sediments. The radiometric investigations revealed that uranium and thorium contents reached up to 710 and 520 ppm, respectively, in the mineralized rocks. This was attributed to the presence of some secondary uranium minerals. All sediments had low values of eTh and K content. The exposure and dose rates exceeded public permissible values in the mineralized sediments. Exposure and dose rates were within the safety range for workers and the public in the non-mineralized sediments. The expected environmental impacts may be low due to the limited occurrence of U-mineralization and corresponding areas for radiation exposure. Some precautions and recommendations were suggested to avoid any possible environmental impacts from areas and/or raw materials of high intensity of natural radiation sources. PMID:18243438

  11. Determination of the risk associated with the natural and anthropogenic radionuclides from the soil of Skardu in Central Karakoram.

    PubMed

    Ali, Manzoor; Wasim, Mohammad; Iqbal, Sajid; Arif, Mohammad; Saif, Farhan

    2013-09-01

    The radioactivity levels were determined in 39 soil samples from six towns of Skardu using gamma-ray spectrometry. The samples were collected at an average altitude of 2293 m above sea level in Central Karakoram. The activity concentration data were analysed by principal component analysis for outlier detection and data structure elucidation and for frequency distributions. The median activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs were found to be 49.8 ± 12.6, 80.9 ± 18.7, 977 ± 91 and 4.37 ± 4.08 Bq kg(-1), respectively. An uncertainty analysis showed that the main contribution to uncertainty budget was from the counting statistics and uncertainty in the reference activity of standard. The activity concentration data showed a positive significant correlation between (226)Ra and (232)Th. Three hazard indices named the radium equivalent activity, external hazard index and internal hazard index were calculated. In the total activity concentration, (40)K accounted for the most (87.5 %), whilst in the radium equivalent activity, (232)Th contributed the most (48.5 %). In the Skardu samples, the air-absorbed dose rate was found to be 112 ± 17 nGy h(-1), annual effective dose rate from terrestrial to be 243 ± 38 μSv y(-1), effective dose rate due to the deposition of (137)Cs on soil to be 1.1 ± 2.4 μSv y(-1) and dose rate from the cosmic radiations to be 1371 ± 107 μSv y(-1). The ratio of mass fractions of Th/U was 4.8 ± 0.6.The results were compared with the similar measurements made in other parts of the world. A comparison with the other cities of Pakistan revealed that the soil in Skardu presented the highest external exposure rate. PMID:23525911

  12. Natural radioactivity distribution and gamma radiation exposure of beach sands close to Kavala pluton, Greece

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Argyrios; Koroneos, Antonios; Christofides, Georgios; Stoulos, Stylianos

    2015-10-01

    This study aims to evaluate the activity concentrations of 238U, 226Ra, 232Th, 228Th and 40K along the beaches of Kavala being adjacent to the rock-types of the Kavala pluton. These ranged from 14-940, 16-1710, 26- 4547, 27-4488 and 194-1307 Bq/kg respectively, representing the highest values of natural radioactivity measured in sediments of Greece. The (%wt.) heavy magnetic (HM) (allanite, amphibole, mica, clinopyroxene, magnetite and hematite) fraction, the heavy non-magnetic (HNM) (monazite, zircon, titanite and apatite) fraction and the total heavy fraction (TH), were correlated with the concentrations of the measured radionuclides in the bulk samples. The heavy fractions seem to control the activity concentrations of 238U and 232Th of all the samples, showing some local differences in the main 238U and 232Th mineral carrier. The measured radionuclides in the beach sands were normalized to the respective values measured in the granitic rocks, which are their most probable parental rocks, so as to provide data upon their enrichment or depletion. The annual equivalent dose varies between 0.01 and 0.35 mSv y-1 for tourists and from 0.03 to 1.48 mSv y-1 for local people working on the beach.

  13. Distribution of rubidium between sodic sanidine and natural silicic liquid

    USGS Publications Warehouse

    Noble, D.C.; Hedge, C.E.

    1970-01-01

    Phenocrysts of sodic sanidine from twelve upper Cenozoic units of silicic ash-flow tuff and lava from the Western United States contain from 0.25 to 0.45 the Rb present in the associated groundmass materials. The ratios of potassium to rubidium in the sanidines are, on the average, about four times greater than those of the groundmass. Separation of phenocrystic sanidine from salic melts provides an efficient method for raising the Rb content and lowering the K/Rb ratio of the melts, although the amount of differentiation probably is limited by continuous reequilibration of the alkalis between crystal and liquid phases through ion exchange. Syenites of cumulate origin will have appreciably lower Rb contents and higher K/Rb ratios than the melts from which they precipitated. Available data on the distribution of Rb between synthetic biotite and K-sanidine demonstrate that the separation of biotite probably will not deplete salic melts in Rb relative to K. ?? 1970 Springer-Verlag.

  14. Resolving LDEF's flux distribution: Orbital (debris?) and natural meteoroid populations

    NASA Technical Reports Server (NTRS)

    Mcdonnell, J. A. M.

    1993-01-01

    A consistent methodology for the collation of data from both penetration and perforation experiments and from data in the Meteoroid and Debris Special Investigator Group (M-D SIG) data-base has led to the derivation of the average impact flux over LDEF's exposure history 1984-1990. Data are first presented for LDEF's N,S,E,W and Space faces ('offset' by 8 deg and 'tilted' by 1 deg respectively). A model fit is derived for ballistic limits of penetration from 1 micron to 1mm of aluminium target, corresponding to impactor masses from 10(exp -18) kg (for rho sub p = 2g/cu cm) to 10(exp -10) kg (for rho sub p = 1g/cu cm). A second order harmonic function is fitted to the N,S,E, and W fluxes to establish the angular distribution at regular size intervals; this fit is then used to provide 'corrected' data corresponding to fluxes applicable to true N,S,E,W and Space directions for a LEO 28.5 degree inclination orbit at a mean altitude of 465 km.

  15. Resolving LDEF's flux distribution: Orbital (debris?) and natural meteoroid populations

    NASA Astrophysics Data System (ADS)

    McDonnell, J. A. M.

    1993-03-01

    A consistent methodology for the collation of data from both penetration and perforation experiments and from data in the Meteoroid and Debris Special Investigator Group (M-D SIG) data-base has led to the derivation of the average impact flux over LDEF's exposure history 1984-1990. Data are first presented for LDEF's N,S,E,W and Space faces ('offset' by 8 deg and 'tilted' by 1 deg respectively). A model fit is derived for ballistic limits of penetration from 1 micron to 1mm of aluminium target, corresponding to impactor masses from 10-18 kg (for rhop = 2g/cu cm) to 10-10 kg (for rhop = 1g/cu cm). A second order harmonic function is fitted to the N,S,E, and W fluxes to establish the angular distribution at regular size intervals; this fit is then used to provide 'corrected' data corresponding to fluxes applicable to true N,S,E,W and Space directions for a LEO 28.5 degree inclination orbit at a mean altitude of 465 km.

  16. Survey of Radionuclide Distributions Resulting from the Church Rock, New Mexico, Uranium Mill Tailings Pond Dam Failure

    SciTech Connect

    Weimer, W. C.; Kinnison, R. R.; Reeves, J. H.

    1981-12-01

    An intensive site survey and on-site analysis program were conducted to evaluate the distribution of four radionucliGes in the general vicinity of Gallup, New Mexico, subsequent to the accidental breach of a uranium mill tailings pond dam and the release of a large quantity of tailings pond materials. The objective of this work was to determine the distribution and concentration levels of {sup 210}Pb, {sup 226}Ra, {sup 230}Th, and {sup 238}U in the arroyo that is immediately adjacent to the uranium tailings pond (pipeline arroyo) and in the Rio Puerco arroyo into which the pipeline arroyo drains. An intensive survey between the United Nuclear Corporation (UNC) Church Rock Mill site and the New Mexico-Arizona state border was performed. Sampling locations were established at approximately 500-ft intervals along the arroyo. During the weeks of September 24 through October 5, 1979, a series of samples was collected from alternate sampling locations along the arroyo. The purpose of this collection of samples and their subsequent analysis was to provide an immediate evaluation of the extent and the levels of radioactive contamination. The data obtained from this extensive survey were then compared to action levels which had been proposed by the Nuclear Regulatory Commission and were adapted by the New Mexico Environmental Improvement Division (NMEID) for {sup 230}Th and {sup 226}Ra concentrations that would require site cleanup. The Pacific Northwest Laboratory/Nuclear Regulatory Commission mobile laboratory van was on-site at the UNC Church Rock Mill from September 22, 1979, through December 13, 1979, and was manned by one or more PNL personnel for all but four weeks of this time period. Approximately 1200 samples associated with the Rio Puerco survey were analyzed 1n the laboratory. An additional 1200 samples related to the Rio Puerco cleanup operations which the United Nuclear Corporation was conducting were analyzed on-site in the mobile laboratory. The purpose of

  17. [Evaluation of the partial contribution of naturally occurring radionuclides and nonradioactive chemically toxic elements in formation of biological effects within the Vicia cracca population inhabiting the area contaminated with uranium-radium production wastes in the Komi Republic].

    PubMed

    Evseeva, T I; Geras'kin, S A; Vakhrusheva, O M

    2014-01-01

    The site contaminated with uranium-radium production wastes in the Komi Republic was studied. The activity concentration of naturally occurring radionuclides (226Ra, 228Th, 238U, 230Th, 232Th, 210Po, and 210Pb), as well as concentrations of nonradioactive chemically toxic elements (Pb, Zn, Cu, As, V, Mo, Sr, Y, and Ba) in the soil samples from the experimental site is 10-183 times higher than reference levels. A chronic exposure to alpha-emitters and nonradioactive chemically toxic elements causes adverse effects in tufted vetch (Vacia cracca L.) both at the cellular (aberration of chromosomes) and population (decrease in the reproductive ability) levels. Radionuclides are the main contributors to the decrease in the reproductive capacity and an increase in the level of the cytogenetic damage in root tip cells of tufted vetch seedlings. As and Pb significantly influence the reproductive capacity of plants. Sr, Zn, Y and P modify the biological effects caused by exposure to radionuclides. Moreover, P and Zn reduce the adverse effects of radionuclides; however, Sr and Y enhance these effects. PMID:25764850

  18. Distribution and nature of CO2 on Enceladus

    NASA Astrophysics Data System (ADS)

    Combe, J. P.; McCord, T. B.; Matson, D.; Johnson, T. V.; Scipioni, F.; Tosi, F.

    2015-12-01

    We present the first global mapping and analysis of CO2 on the surface of Enceladus, and we report the largest concentrations of free CO2 on the southern polar region using the Visual and Infrared Mapping Spectrometer (VIMS) on Cassini. Free CO2 ice and complexed CO2 were already reported near the South Pole (Brown et al., Science, 2006; Hansen, LPSC, 2010). Our work focuses on determining the amount, location and molecular state of CO2 on Enceladus, which could help identify and model geophysical processes that currently occur in the interior. One hypothesis for bringing heat and chemicals to the surface is a warm subsurface ocean containing dissolved gases, mostly CO2 (Postberg F. et al., Nature, 2009). Therefore, our observations are consistent with erupted and condensed materials onto Enceladus' surface (Matson et al., Icarus, 2012; Matson et al. AGU Fall meeting 2015). Free CO2 ice absorbs at 4.268 µm (Sandford and Allamandola, 1990) and CO2 complexed with other molecules absorbs at 4.247 μm (Chaban et al., Icarus, 2007). The Enceladus case is complicated because both free and complexed CO2 are present, and the absorption band of interest is shallow and close to the instrument detection limit. Many of the few Enceladus VIMS data sets have significant and sometimes unusual noise, which we attempted to avoid or remove. We utilized all VIMS data sets available that were collected over ten years of the Cassini mission as a way to improve the detection statistics and signal to noise. We also used wavelengths near 2.7 μm where CO2 has a narrow absorption as a filter to help identify CO2-rich areas. Finally, we selected observations that have spatial resolution better than 100 km in order to create a map that can be compared with the largest fractures, known as Tiger Stripes, in the southern polar region.

  19. Nature, Distribution, and Origin of Titan's Undifferentiated Plains ("Blandlands")

    NASA Astrophysics Data System (ADS)

    Lopes, R. M. C.; Malaska, M. J.; Solomonidou, A.; Le Gall, A. A.; Janssen, M. A.; Neish, C.; Turtle, E. P.; Birch, S. P.; Hayes, A.; Radebaugh, J.; Coustenis, A.; Stiles, B. W.; Kirk, R. L.; Mitchell, K. L.; Lawrence, K. J.

    2015-12-01

    The Undifferentiated Plains on Titan are vast expanses of terrains that appear radar-dark and fairly uniform in Cassini Synthetic Aperture Radar (SAR) images and are often referred to as "blandlands". While the interpretation of several other geologic units on Titan - such as dunes, lakes, and well-preserved impact craters - has been relatively straightforward, the origin of the Undifferentiated Plains has remained elusive. SAR images show that these terrains are mostly found at mid-latitudes and show no major topographic features. Their gradational boundaries and paucity of recognizable features make geologic interpretation challenging. We mapped the distribution of these terrains using SAR swaths up to flyby T92 (7/2013), which cover > 50% of Titan's surface. We compared SAR images with other data sets, including topography, the response from RADAR radiometry, hyperspectral imaging data from Cassini's Visual and Infrared Mapping Spectrometer (VIMS), and near infrared imaging from the Imaging Science Subsystem. We examined and evaluated different formation mechanisms, including (i) cryovolcanic origin, consisting of overlapping flows of low relief or (ii) sedimentary origins, resulting from fluvial/lacustrine or aeolian deposition, or accumulation of photolysis products created in the atmosphere. Our results are consistent with a sedimentary origin for the Undifferentiated Plains. We discuss the possible contributing processes (photolysis products, aeolian, and fluvial/lacustrine deposition). VIMS and radiometry analysis of the Undifferentiated Plains presented here is consistent with tholin-like materials as a major component for the materials in the Plains. We conclude that the Undifferentiated Plains are sedimentary in origin and likely formed by a combination of aeolian, fluvial and lacustrine deposition, together with atmospheric organic particle deposition, possibly in differing proportions depending on location.

  20. Nature, distribution, and origin of Titan's Undifferentiated Plains

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly M. C.; Malaska, M. J.; Solomonidou, A.; Le Gall, A.; Janssen, M. A.; Neish, C. D.; Turtle, E. P.; Birch, S. P. D.; Hayes, A. G.; Radebaugh, J.; Coustenis, A.; Schoenfeld, A.; Stiles, B. W.; Kirk, R. L.; Mitchell, K. L.; Stofan, E. R.; Lawrence, K. J.

    2016-05-01

    The Undifferentiated Plains on Titan, first mapped by Lopes et al. (Lopes, R.M.C. et al., 2010. Icarus, 205, 540-588), are vast expanses of terrains that appear radar-dark and fairly uniform in Cassini Synthetic Aperture Radar (SAR) images. As a result, these terrains are often referred to as "blandlands". While the interpretation of several other geologic units on Titan - such as dunes, lakes, and well-preserved impact craters - has been relatively straightforward, the origin of the Undifferentiated Plains has remained elusive. SAR images show that these "blandlands" are mostly found at mid-latitudes and appear relatively featureless at radar wavelengths, with no major topographic features. Their gradational boundaries and paucity of recognizable features in SAR data make geologic interpretation particularly challenging. We have mapped the distribution of these terrains using SAR swaths up to flyby T92 (July 2013), which cover >50% of Titan's surface. We compared SAR images with other data sets where available, including topography derived from the SARTopo method and stereo DEMs, the response from RADAR radiometry, hyperspectral imaging data from Cassini's Visual and Infrared Mapping Spectrometer (VIMS), and near infrared imaging from the Imaging Science Subsystem (ISS). We examined and evaluated different formation mechanisms, including (i) cryovolcanic origin, consisting of overlapping flows of low relief or (ii) sedimentary origins, resulting from fluvial/lacustrine or aeolian deposition, or accumulation of photolysis products created in the atmosphere. Our analysis indicates that the Undifferentiated Plains unit is consistent with a composition predominantly containing organic rather than icy materials and formed by depositional and/or sedimentary processes. We conclude that aeolian processes played a major part in the formation of the Undifferentiated Plains; however, other processes (fluvial, deposition of photolysis products) are likely to have contributed

  1. ASSESSING ABUNDANCE DISTRIBUTIONS IN NATURAL COMMUNITIES OF ECTOMYCORRHIZAS ALONG AN ENVIRONMENTAL GRADIENT

    EPA Science Inventory

    Alpha diversity indices often fail to distinguish between natural populations that a more detailed investigation of the distribution of ramets among types would show are quite different. We studied the effectiveness of applying SHE analyses to morphotype classifications of ectom...

  2. Spatial bedrock erosion distribution in a natural gorge

    NASA Astrophysics Data System (ADS)

    Beer, A. R.; Turowski, J. M.; Kirchner, J. W.

    2015-12-01

    Quantitative analysis of morphological evolution both in terrestrial and planetary landscapes is of increasing interest in the geosciences. In mountainous regions, bedrock channel formation as a consequence of the interaction of uplift and erosion processes is fundamental for the entire surface evolution. Hence, the accurate description of bedrock channel development is important for landscape modelling. To verify existing concepts developed in the lab and to analyse how in situ channel erosion rates depend on the interrelations of discharge, sediment transport and topography, there is a need of highly resolved topographic field data. We analyse bedrock erosion over two years in a bedrock gorge downstream of the Gorner glacier above the town of Zermatt, Switzerland. At the study site, the Gornera stream cuts through a roche moutonnée in serpentine rock of 25m length, 5m width and 8m depth. We surveyed bedrock erosion rates using repeat terrestrial laser scanning (TLS) with an average point spacing of 5mm. Bedrock erosion rates in direction of the individual surface normals were studied directly on the scanned point clouds applying the M3C2 algorithm (Lague et al., 2013, ISPRS). The surveyed erosion patterns were compared to a simple stream erosivity visualisation obtained from painted bedrock sections at the study location. Spatially distributed erosion rates on bedrock surfaces based on millions of scan points allow deduction of millimeter-scale mean annual values of lateral erosion, incision and downstream erosion on protruding streambed surfaces. The erosion rate on a specific surface point is shown to depend on the position of this surface point in the channel's cross section, its height above the streambed and its spatial orientation to the streamflow. Abrasion by impacting bedload was likely the spatially dominant erosion process, as confirmed by the observed patterns along the painted bedrock sections. However, a single plucking event accounted for the half

  3. Model documentation: Natural gas transmission and distribution model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1995-02-17

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of integrated Analysis and Forecasting of the Energy information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The methodology employed allows the analysis of impacts of regional capacity constraints in the interstate natural gas pipeline network and the identification of pipeline capacity expansion requirements. There is an explicit representation of core and noncore markets for natural gas transmission and distribution services, and the key components of pipeline tariffs are represented in a pricing algorithm. Natural gas pricing and flow patterns are derived by obtaining a market equilibrium across the three main elements of the natural gas market: the supply element, the demand element, and the transmission and distribution network that links them. The NGTDM consists of four modules: the Annual Flow Module, the Capacity F-expansion Module, the Pipeline Tariff Module, and the Distributor Tariff Module. A model abstract is provided in Appendix A.

  4. Quantifying variation in 7Be depth distribution under simulated rainfall for an increased understanding of fallout radionuclide use in erosion assessments

    NASA Astrophysics Data System (ADS)

    Ryken, Nick; Al-Barri, Bashar; Blake, William; Taylor, Alex; Boeckx, Pascal; Verdoodt, Ann

    2015-04-01

    trend could be observed, with Be being more concentrated near the surface at X having an average surface Be concentration of 8.9 µg/g compared to 4.1 µg/g at location Y. In addition, elevated Be concentrations were observed till an average mass depth of 6.5 kg/m² at X while this was up to 16.7 kg/m² at location Y. The h0 followed this trend with higher values at the Y location, showing a deeper penetration of Be in the soil. After the rainfall simulations, infiltration and bulk density measurements respectively showed lower infiltration and a higher compaction at location X, indicating the importance of soil structure on the depth distribution of short term fallout radionuclides. X-ray tomography is performed to map the pore distribution in the cores. These results indicate the importance of selecting proper reference sites. As soil structure can strongly influence 7Be depth distribution, it can strongly influence total modeled sediment redistribution. Hence selected reference sites should have similar soil structure and a similar recent history of tillage. Finally, the use of a FSIC is strongly recommended for 7Be studies.

  5. Impact of Higher Natural Gas Prices on Local Distribution Companies and Residential Customers

    EIA Publications

    2007-01-01

    This report examines some of the problems faced by natural gas consumers as a result of increasing heating bills in recent years and problems associated with larger amounts of uncollectible revenue and lower throughput for the local distribution companies (LDCs) supplying the natural gas.

  6. Using natural radionuclides 210Po and 210Pb in GEOTRACES data from the North Atlantic to estimate particulate and biologically reactive trace element scavenging and regeneration

    NASA Astrophysics Data System (ADS)

    Rigaud, Sylvain; Church, Thomas

    2016-04-01

    Central to understanding the coupling of oceanic carbon and nutrient cycles are trace elements that can limit ocean production and ultimately climate change. These include elements that are both lithogenic (particle reactive) and biogenic (biologically reactive) central to particle scavenging, exchange and bioavailability. The natural 210Po and 210Pb radionuclide (granddaughter/parent) pair provides the radiometric means to model particle scavenging and exchange in the ocean on monthly to annual time scales. Data on dissolved (<0.2 μm) and particulate (>0.2 μm, >53μm) 210Po (t1/2= 138.4 d) and 210Pb (T1/2 = 22.3 y) are available from seven complete water profiles during two U.S. GEOTRACES cruises that transited the North Atlantic during fall 2010 and 2011. The transects correspond to a wide range of marine environments: coastal slopes at the western and eutrophic up-welling at the eastern margins, Saharan dust sources from the east, hydro-thermal vents in the TAG plume on the Mid-Atlantic Ridge, and oligotrophic gyres in both the western and eastern basins. Steady state box modeling at each depth interval was employed to estimate radionuclide exchange rates at the fine-large particle and fine particulate-dissolved interface, in terms of biological uptake, and net of radioactive support or decay. By proxy, the results should predict the rates of biological (210Po) and particle reactive (210Pb) trace element adsorption and resorption, vertical particulate and carbon export, and respective residence times. The model results show the contrasting chemical behaviour of the two nuclides over the large range of oceanic conditions encountered in the North Atlantic. In the surface ocean, 210Po scavenging is linearly correlated with the concentration of particulate organic carbon (POC) in large particles, supporting the role of biogenic particles in 210Po bioaccumulation and export. At depth, 210Po exhibits significant widespread deficit with respect to 210Pb, which could

  7. Radionuclide migration studies on tonalite

    SciTech Connect

    Hoelttae, P.; Siitari-Kauppi, M.; Hakanen, M.; Hautojaervi, A.

    1993-12-31

    Migration of water, chloride, sodium, and calcium in tonalite was studied, using dynamic column and static through-diffusion methods. Autoradiography of rocks impregnated with {sup 14}C-methylmethacrylate was introduced in order to determine the spatial porosity distribution, as well as to identify and visualize the migration pathways of non-sorbing radionuclides in tonalite matrix as the mm-cm scale. The migration routes of sorbing radionuclides and the sorptive minerals in tonalite were determined by autoradiographic methods, using {sup 45}Ca as a tracer. Transport of radionuclides was interpreted, using models for hydrodynamic dispersion with diffusion into the rock matrix. In tonalite, porous minerals were distributed homogeneously in matrix and, therefore, retardation capacity of the rock matrix was found to be high.

  8. Distribution of natural halocarbons in marine boundary air over the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Yokouchi, Yoko; Inoue, Jun; Toom-Sauntry, Desiree

    2013-08-01

    Ongoing environmental changes in the Arctic will affect the exchange of natural volatile organic compounds between the atmosphere and the Arctic Ocean. Among these compounds, natural halocarbons play an important role in atmospheric ozone chemistry. We measured the distribution of five major natural halocarbons (methyl iodide, bromoform, dibromomethane, methyl chloride, and methyl bromide) together with dimethyl sulfide and tetrachloroethylene in the atmosphere over the Arctic Ocean (from the Bering Strait to 79°N) and along the cruise path to and from Japan. Methyl iodide, bromoform, and dibromomethane were most abundant near perennial sea ice in air masses derived from coastal regions and least abundant in the northernmost Arctic, where the air masses had passed over the ice pack, whereas methyl chloride and methyl bromide showed the opposite distribution pattern. Factors controlling those distributions and future prospects for natural halocarbons in the Arctic are discussed.

  9. Field test of the IMEEDS radionuclide sampling system

    SciTech Connect

    Bandong, B; Bianchini, G; Esser, B; Volpe, A M.

    1998-09-15

    This report describes the function and performance of a seawater sampling system. The purpose of the sampling system is to process water and isolate, or concentrate man-made radionuclides present in the marine environment. Many of these isotopes are present in natural waters at extremely low levels, if at all. Also, biogeochemical processes in the environment sequester elements so that any given analyte may be in a compound, molecular, or ionic state, and associated with solid, colloidal and dissolved phases. The distribution of radioisotopes in natural waters is controlled by chemical speciation, pH, temperature, redox conditions, complex formation, adsorption and desorption, salinity, conductivity, and hydrolytic colloid formation (Harvey et al., 1990; von Gunten and Benes, 1995). Therefore, the goal of this work is to develop a sampler that is capable of isolating suites of radionuclides as they are found in the environment.

  10. Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1998-01-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. Subsequent chapters of this report provide: an overview of NGTDM; a description of the interface between the NEMS and NGTDM; an overview of the solution methodology of the NGTDM; the solution methodology for the Annual Flow Module; the solution methodology for the Distributor Tariff Module; the solution methodology for the Capacity Expansion Module; the solution methodology for the Pipeline Tariff Module; and a description of model assumptions, inputs, and outputs.

  11. Radionuclides in Chesapeake Bay sediments

    NASA Technical Reports Server (NTRS)

    Cressy, P. J., Jr.

    1976-01-01

    Natural and manmade gamma-ray emitting radionuclides were measured in Chesapeake Bay sediments taken near the Calvert Cliffs Nuclear Power Plant site. Samples represented several water depths, at six locations, for five dates encompassing a complete seasonal cycle. Radionuclide contents of dry sediments ranged as follows: Tl-208, 40 to 400 pCi/kg; Bi-214, 200 to 800 pCi/kg; K, 0.04 to 2.1 percent; Cs-137 5 to 1900 pCi/kg; Ru106, 40 to 1000 pCikg Co60, 1 to 27 pCi/kg. In general, radionuclide contents were positively correlated with each other and negatively correlated with sediment grain size.

  12. The relations between natural gas hydrate distribution and structure on Muli basin Qinghai province

    NASA Astrophysics Data System (ADS)

    Yu, C.; Li, Y.; Lu, Z.; Luo, S.; Qu, C.; Tan, S.; Zhang, P.

    2014-12-01

    The Muli area is located in a depression area which between middle Qilian and south Qilian tectonic elements. The natural gas hydrate stratum belongs the Jurassic series coal formation stratum, the main lithological character clamps the purple mudstone, the siltstone, the fine grain sandstone and the black charcoal mudstone for the green gray. The plutonic metamorphism is primarily deterioration function of the Muli area coal, is advantageous in forming the coal-bed gas. Cretaceous system, the Paleogene System and Neogene System mainly include the fine grain red clastic rock and clay stone. The distribution of Quaternary is widespread. The ice water - proluvial and glacier deposit are primarily depositional mode. The Qilian Montanan Muli permafrost area has the good gas source condition (Youhai Zhu 2006) and rich water resources. It is advantage to forming the natural gas hydrate. The natural gas hydrate is one kind of new latent energy, widely distributes in the mainland marginal sea bottom settlings and land permanent tundra. Through researching the area the structure ,the deposition carries on the analysis and responds the characteristic analysis simulation in the rock physics analysis and the seismic in the foundation, and then the reflected seismic data carried by tectonic analysis processing and the AVO characteristic analysis processing reveal that the research area existence natural gas hydrate (already by drilling confirmation) and the natural gas hydrate distribution and the structure relations is extremely close. In the structure development area, the fault and the crevasse crack growing, the natural gas hydrate distribution characteristic is obvious (this is also confirmed the storing space of natural gas hydrate in this area is mainly crevasse crack). This conclusion also agree with the actual drilling result. The research prove that the distribution of natural gas hydrate in this area is mainly controlled by structure control. The possibility of fault

  13. FINAL REPORT. DISTRIBUTION AND SOLUBILITY OF RADIONUCLIDES AND NEUTRON ABSORBERS IN WASTE FORMS FOR DISPOSITION OF PLUTONIUM ASH AND SCRAPS, EXCESS PLUTONIUM, AND MISCELLANEOUS SPENT NUCLEAR FUELS

    EPA Science Inventory

    The objective of this multi-institutional research effort was to understand how radionuclides, neutron absorbers, and other waste species are incorporated into single-phase amorphous matrices and ceramics. This was to provide DOE with a methodology to develop glasses and ceramics...

  14. Correlated Percolation, Fractal Structures, and Scale-Invariant Distribution of Clusters in Natural Images

    PubMed Central

    Saremi, Saeed; Sejnowski, Terrence J.

    2016-01-01

    Natural images are scale invariant with structures at all length scales. We formulated a geometric view of scale invariance in natural images using percolation theory, which describes the behavior of connected clusters on graphs. We map images to the percolation model by defining clusters on a binary representation for images. We show that critical percolating structures emerge in natural images and study their scaling properties by identifying fractal dimensions and exponents for the scale-invariant distributions of clusters. This formulation leads to a method for identifying clusters in images from underlying structures as a starting point for image segmentation. PMID:26415153

  15. Correlated Percolation, Fractal Structures, and Scale-Invariant Distribution of Clusters in Natural Images.

    PubMed

    Saremi, Saeed; Sejnowski, Terrence J

    2016-05-01

    Natural images are scale invariant with structures at all length scales.We formulated a geometric view of scale invariance in natural images using percolation theory, which describes the behavior of connected clusters on graphs.We map images to the percolation model by defining clusters on a binary representation for images. We show that critical percolating structures emerge in natural images and study their scaling properties by identifying fractal dimensions and exponents for the scale-invariant distributions of clusters. This formulation leads to a method for identifying clusters in images from underlying structures as a starting point for image segmentation. PMID:26415153

  16. Potential for post-closure radionuclide redistribution due to biotic intrusion: aboveground biomass, litter production rates, and the distribution of root mass with depth at material disposal area G, Los Alamos National Laboratory

    SciTech Connect

    French, Sean B; Christensen, Candace; Jennings, Terry L; Jaros, Christopher L; Wykoff, David S; Crowell, Kelly J; Shuman, Rob

    2008-01-01

    Low-level radioactive waste (LLW) generated at the Los Alamos National Laboratories (LANL) is disposed of at LANL's Technical Area (T A) 54, Material Disposal Area (MDA) G. The ability of MDA G to safely contain radioactive waste during current and post-closure operations is evaluated as part of the facility's ongoing performance assessment (PA) and composite analysis (CA). Due to the potential for uptake and incorporation of radio nuclides into aboveground plant material, the PA and CA project that plant roots penetrating into buried waste may lead to releases of radionuclides into the accessible environment. The potential amount ofcontamination deposited on the ground surface due to plant intrusion into buried waste is a function of the quantity of litter generated by plants, as well as radionuclide concentrations within the litter. Radionuclide concentrations in plant litter is dependent on the distribution of root mass with depth and the efficiency with which radionuclides are extracted from contaminated soils by the plant's roots. In order to reduce uncertainties associated with the PA and CA for MDA G, surveys are being conducted to assess aboveground biomass, plant litter production rates, and root mass with depth for the four prominent vegetation types (grasses, forbs, shrubs and trees). The collection of aboveground biomass for grasses and forbs began in 2007. Additional sampling was conducted in October 2008 to measure root mass with depth and to collect additional aboveground biomass data for the types of grasses, forbs, shrubs, and trees that may become established at MDA G after the facility undergoes final closure, Biomass data will be used to estimate the future potential mass of contaminated plant litter fall, which could act as a latent conduit for radionuclide transport from the closed disposal area. Data collected are expected to reduce uncertainties associated with the PA and CA for MDA G and ultimately aid in the assessment and subsequent

  17. Natural gas distribution system leak pinpointing survey. Final report, October 1993-November 1994

    SciTech Connect

    Kinast, J.A.; Kostro, J.H.; Huebler, J.E.; Tamosaitis, V.

    1995-03-01

    The purpose of this effort was to conduct a survey of the top 100 natural gas distribution companies in the United States to collect information about their leak pinpointing procedures and ascertain what, if any, R&D is needed to improve their leak pinpointing operations

  18. Estimating the distribution of harvested estuarine bivalves with natural-history-based habitat suitability models

    EPA Science Inventory

    Habitat suitability models are useful to forecast how environmental change may affect the abundance or distribution of species of concern. In the case of harvested bivalves, those models may be used to estimate the vulnerability of this valued ecosystem good to natural or human-...

  19. Study On Temperature Distribution In T Fittings - Polyethylene Natural Gas Pipes Assemblies

    NASA Astrophysics Data System (ADS)

    Avrigean, Eugen

    2015-09-01

    The present paper intends to approach theoretically and experimentally an important topic concerning the operational safety of the polyethylene pipes used in natural gas distribution. We discuss the influence of temperature in the high density polyethylene elbows during welding to the polyethylene pipes.

  20. The Nature of Leadership: A Case Study of Distributed Leadership amidst a Participative Change Effort

    ERIC Educational Resources Information Center

    Coleman, Eric D.

    2014-01-01

    The purpose of this study was to examine the nature of distributed leadership at the University of ABC's SCPS, as the School worked to transform itself through reorganization. The study examined the perceptions of key leaders and members of the implementation team as they sought to understand the implementation of a more participative approach to…

  1. Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments.

    PubMed

    Hendrick, Margaret F; Ackley, Robert; Sanaie-Movahed, Bahare; Tang, Xiaojing; Phillips, Nathan G

    2016-06-01

    Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing 'superemitter' leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as 'safely leaking.' Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks. PMID:27023280

  2. Optimal Capacity and Location Assessment of Natural Gas Fired Distributed Generation in Residential Areas

    NASA Astrophysics Data System (ADS)

    Khalil, Sarah My

    With ever increasing use of natural gas to generate electricity, installed natural gas fired microturbines are found in residential areas to generate electricity locally. This research work discusses a generalized methodology for assessing optimal capacity and locations for installing natural gas fired microturbines in a distribution residential network. The overall objective is to place microturbines to minimize the system power loss occurring in the electrical distribution network; in such a way that the electric feeder does not need any up-gradation. The IEEE 123 Node Test Feeder is selected as the test bed for validating the developed methodology. Three-phase unbalanced electric power flow is run in OpenDSS through COM server, and the gas distribution network is analyzed using GASWorkS. The continual sensitivity analysis methodology is developed to select multiple DG locations and annual simulation is run to minimize annual average losses. The proposed placement of microturbines must be feasible in the gas distribution network and should not result into gas pipeline reinforcement. The corresponding gas distribution network is developed in GASWorkS software, and nodal pressures of the gas system are checked for various cases to investigate if the existing gas distribution network can accommodate the penetration of selected microturbines. The results indicate the optimal locations suitable to place microturbines and capacity that can be accommodated by the system, based on the consideration of overall minimum annual average losses as well as the guarantee of nodal pressure provided by the gas distribution network. The proposed method is generalized and can be used for any IEEE test feeder or an actual residential distribution network.

  3. Natural radionuclide of Po210 in the edible seafood affected by coal-fired power plant industry in Kapar coastal area of Malaysia

    PubMed Central

    2011-01-01

    Background Po210 can be accumulated in various environmental materials, including marine organisms, and contributes to the dose of natural radiation in seafood. The concentration of this radionuclide in the marine environment can be influenced by the operation of a coal burning power plant but existing studies regarding this issue are not well documented. Therefore, the aim of this study was to estimate the Po210 concentration level in marine organisms from the coastal area of Kapar, Malaysia which is very near to a coal burning power plant station and to assess its impact on seafood consumers. Methods Concentration of Po210 was determined in the edible muscle of seafood and water from the coastal area of Kapar, Malaysia using radiochemical separation and the Alpha Spectrometry technique. Results The activities of Po210 in the dissolved phase of water samples ranged between 0.51 ± 0.21 and 0.71 ± 0.24 mBql-1 whereas the particulate phase registered a range of 50.34 ± 11.40 to 72.07 ± 21.20 Bqkg-1. The ranges of Po210 activities in the organism samples were 4.4 ± 0.12 to 6.4 ± 0.95 Bqkg-1 dry wt in fish (Arius maculatus), 45.7 ± 0.86 to 54.4 ± 1.58 Bqkg-1 dry wt in shrimp (Penaeus merguiensis) and 104.3 ± 3.44 to 293.8 ± 10.04 Bqkg-1 dry wt in cockle (Anadara granosa). The variation of Po210 in organisms is dependent on the mode of their life style, ambient water concentration and seasonal changes. The concentration factors calculated for fish and molluscs were higher than the recommended values by the IAEA. An assessment of daily intake and received dose due to the consumption of seafood was also carried out and found to be 2083.85 mBqday-1person-1 and 249.30 μSvyr-1 respectively. These values are comparatively higher than reported values in other countries. Moreover, the transformation of Po210 in the human body was calculated and revealed that a considerable amount of Po210 can be absorbed in the internal organs. The calculated values of life time

  4. Stretched exponential distributions in nature and economy: ``fat tails'' with characteristic scales

    NASA Astrophysics Data System (ADS)

    Laherrère, J.; Sornette, D.

    1998-04-01

    To account quantitatively for many reported "natural" fat tail distributions in Nature and Economy, we propose the stretched exponential family as a complement to the often used power law distributions. It has many advantages, among which to be economical with only two adjustable parameters with clear physical interpretation. Furthermore, it derives from a simple and generic mechanism in terms of multiplicative processes. We show that stretched exponentials describe very well the distributions of radio and light emissions from galaxies, of US GOM OCS oilfield reserve sizes, of World, US and French agglomeration sizes, of country population sizes, of daily Forex US-Mark and Franc-Mark price variations, of Vostok (near the south pole) temperature variations over the last 400 000 years, of the Raup-Sepkoski's kill curve and of citations of the most cited physicists in the world. We also discuss its potential for the distribution of earthquake sizes and fault displacements. We suggest physical interpretations of the parameters and provide a short toolkit of the statistical properties of the stretched exponentials. We also provide a comparison with other distributions, such as the shifted linear fractal, the log-normal and the recently introduced parabolic fractal distributions.

  5. Spatial Distribution of Bed Particles in Natural Boulder-Bed Streams

    NASA Astrophysics Data System (ADS)

    Clancy, K. F.; Prestegaard, K. L.

    2001-12-01

    The Wolman pebble count is used to obtain the size distribution of bed particles in natural streams. Statistics such as median particle size (D50) are used in resistance calculations. Additional information such as bed particle heterogeneity may also be obtained from the particle distribution, which is used to predict sediment transport rates (Hey, 1979), (Ferguson, Prestegaard, Ashworth, 1989). Boulder-bed streams have an extreme range of particles in the particle size distribution ranging from sand size particles to particles larger than 0.5-m. A study of a natural boulder-bed reach demonstrated that the spatial distribution of the particles is a significant factor in predicting sediment transport and stream bed and bank stability. Further experiments were performed to test the limits of the spatial distribution's effect on sediment transport. Three stream reaches 40-m in length were selected with similar hydrologic characteristics and spatial distributions but varying average size particles. We used a grid 0.5 by 0.5-m and measured four particles within each grid cell. Digital photographs of the streambed were taken in each grid cell. The photographs were examined using image analysis software to obtain particle size and position of the largest particles (D84) within the reach's particle distribution. Cross section, topography and stream depth were surveyed. Velocity and velocity profiles were measured and recorded. With these data and additional surveys of bankfull floods, we tested the significance of the spatial distributions as average particle size decreases. The spatial distribution of streambed particles may provide information about stream valley formation, bank stability, sediment transport, and the growth rate of riparian vegetation.

  6. Radionuclide deposition control

    DOEpatents

    Brehm, William F.; McGuire, Joseph C.

    1980-01-01

    The deposition of radionuclides manganese-54, cobalt-58 and cobalt-60 from liquid sodium coolant is controlled by providing surfaces of nickel or high nickel alloys to extract the radionuclides from the liquid sodium, and by providing surfaces of tungsten, molybdenum or tantalum to prevent or retard radionuclide deposition.

  7. Distribution and Solubility of Radionuclides and Neutron Absorbers in Waste Forms for Disposition of Plutonium Ash and Scraps, Excess Plutonium, and Miscellaneous Spent Nuclear Fuels

    SciTech Connect

    Dr. Denis M. Strachan; Dr. David K. Shuh; Dr. Rodney C. Ewing; Dr. Eric R. Vance

    2002-09-23

    The initial goal of this project was to investigate the solubility of radionuclides in glass and other potential waste forms for the purpose of increasing the waste loading in glass and ceramic waste forms. About one year into the project, the project decided to focus on two potential waste forms - glass at PNNL and itianate ceramics at the Australian Nuclear Science and Technology Organisation (ANSTO).

  8. Isotopic ratio and vertical distribution of radionuclides in soil affected by the accident of Fukushima Dai-ichi nuclear power plants.

    PubMed

    Fujiwara, Takeshi; Saito, Takumi; Muroya, Yusa; Sawahata, Hiroyuki; Yamashita, Yuji; Nagasaki, Shinya; Okamoto, Koji; Takahashi, Hiroyuki; Uesaka, Mitsuru; Katsumura, Yosuke; Tanaka, Satoru

    2012-11-01

    The results of γ analyses of soil samples obtained from 50 locations in Fukushima prefecture on April 20, 2011, revealed the presence of a spectrum of radionuclides resulted from the accident of the Fukushima Dai-ichi nuclear power plant (FDNPP). The sum γ radioactivity concentration ranged in more than 3 orders of magnitude, depending on the sampling locations. The contamination of soils in the northwest of the FDNPP was considerable. The (131)I/(137)Cs activity ratios of the soil samples plotted as a function of the distance from the F1 NPPs exhibited three distinctive patterns. Such patterns would reflect not only the different deposition behaviors of these radionuclides, but also on the conditions of associated release events such as temperature and compositions and physicochemical forms of released radionuclides. The (136)Cs/(137)Cs activity ratio, on the other hand, was considered to only reflect the difference in isotopic compositions of source materials. Two locations close to the NPP in the northwest direction were found to be depleted in short-lived (136)Cs. This likely suggested the presence of distinct sources with different (136)Cs/(137)Cs isotopic ratios, although their details were unknown at present. Vertical γ activity profiles of (131)I and (137)Cs were also investigated, using 20-30 cm soil cores in several locations. About 70% or more of the radionuclides were present in the uppermost 2-cm regions. It was found that the profiles of (131)I/(137)Cs activity ratios showed maxima in the 2-4 cm regions, suggesting slightly larger migration of the former nuclide. PMID:22634028

  9. Emergence of Visual Saliency from Natural Scenes via Context-Mediated Probability Distributions Coding

    PubMed Central

    Xu, Jinhua; Yang, Zhiyong; Tsien, Joe Z.

    2010-01-01

    Visual saliency is the perceptual quality that makes some items in visual scenes stand out from their immediate contexts. Visual saliency plays important roles in natural vision in that saliency can direct eye movements, deploy attention, and facilitate tasks like object detection and scene understanding. A central unsolved issue is: What features should be encoded in the early visual cortex for detecting salient features in natural scenes? To explore this important issue, we propose a hypothesis that visual saliency is based on efficient encoding of the probability distributions (PDs) of visual variables in specific contexts in natural scenes, referred to as context-mediated PDs in natural scenes. In this concept, computational units in the model of the early visual system do not act as feature detectors but rather as estimators of the context-mediated PDs of a full range of visual variables in natural scenes, which directly give rise to a measure of visual saliency of any input stimulus. To test this hypothesis, we developed a model of the context-mediated PDs in natural scenes using a modified algorithm for independent component analysis (ICA) and derived a measure of visual saliency based on these PDs estimated from a set of natural scenes. We demonstrated that visual saliency based on the context-mediated PDs in natural scenes effectively predicts human gaze in free-viewing of both static and dynamic natural scenes. This study suggests that the computation based on the context-mediated PDs of visual variables in natural scenes may underlie the neural mechanism in the early visual cortex for detecting salient features in natural scenes. PMID:21209963

  10. Nature and distribution of surficial deposits in Chryse Planitia and vicinity, Mars

    NASA Technical Reports Server (NTRS)

    Arvidson, Raymond E.; Guinness, Edward A.; Dale-Bannister, Mary A.; Adams, John; Smith, Milton

    1989-01-01

    The properties and lateral distribution of surficial units for the Mutch Memorial Station region are examined, using color images of the dust deposits in the region obtained at variable incidence angles during sol 611. The radiance factors from the region are compared with values derived from Viking Orbiter images and the materials in and around the region are described. Viking, earth-based, and laboratory spectra are compared and a model is constructed for the nature and distribution of surficial units in the Chryse Planitia region.

  11. [Ecological distribution of macrofungi in Qingliang Mountain Natural Reserve, Anhui Province].

    PubMed

    Ke, Lixia; Yang, Chao

    2003-10-01

    The north side of Qingliang Mountain Natural Reserveis is very rich of macrofungi resources. There are 160 species, belonging to 72 genera, 38 families, 10 orders and 2 classes, and distributing in the evergreen broadleaf forest, Pinus massoniana forest, evergreen-decidous mixed broadleaf forest, and Pinus taiwanensis forest. According to their economic value, these macrofungi may be grouped into two types: edible (72 species) and medicinal (55 species); and according their ecological habitat, they may be grouped into lignicolous (68 species), entomophilous (84 species), and ectomycorrhizal (21 species). Our study showed a certain regularity of their distribution, i.e., it varied with the ecological conditions of forests, tree species, soil types and altitude. Many economical macrofungi in this region could serve as one of the important natural resources, and had great potential usage on the edibility, medicinal and forestation. PMID:14986378

  12. Vertical Distribution and Estimated Doses from Artificial Radionuclides in Soil Samples around the Chernobyl Nuclear Power Plant and the Semipalatinsk Nuclear Testing Site

    PubMed Central

    Taira, Yasuyuki; Hayashida, Naomi; Tsuchiya, Rimi; Yamaguchi, Hitoshi; Takahashi, Jumpei; Kazlovsky, Alexander; Urazalin, Marat; Rakhypbekov, Tolebay; Yamashita, Shunichi; Takamura, Noboru

    2013-01-01

    For the current on-site evaluation of the environmental contamination and contributory external exposure after the accident at the Chernobyl Nuclear Power Plant (CNPP) and the nuclear tests at the Semipalatinsk Nuclear Testing Site (SNTS), the concentrations of artificial radionuclides in soil samples from each area were analyzed by gamma spectrometry. Four artificial radionuclides (241Am, 134Cs, 137Cs, and 60Co) were detected in surface soil around CNPP, whereas seven artificial radionuclides (241Am, 57Co, 137Cs, 95Zr, 95Nb, 58Co, and 60Co) were detected in surface soil around SNTS. Effective doses around CNPP were over the public dose limit of 1 mSv/y (International Commission on Radiological Protection, 1991). These levels in a contaminated area 12 km from Unit 4 were high, whereas levels in a decontaminated area 12 km from Unit 4 and another contaminated area 15 km from Unit 4 were comparatively low. On the other hand, the effective doses around SNTS were below the public dose limit. These findings suggest that the environmental contamination and effective doses on the ground definitely decrease with decontamination such as removing surface soil, although the effective doses of the sampling points around CNPP in the present study were all over the public dose limit. Thus, the remediation of soil as a countermeasure could be an extremely effective method not only for areas around CNPP and SNTS but also for areas around the Fukushima Dai-ichi Nuclear Power Plant (FNPP), and external exposure levels will be certainly reduced. Long-term follow-up of environmental monitoring around CNPP, SNTS, and FNPP, as well as evaluation of the health effects in the population residing around these areas, could contribute to radiation safety and reduce unnecessary exposure to the public. PMID:23469013

  13. Vertical distribution and estimated doses from artificial radionuclides in soil samples around the Chernobyl nuclear power plant and the Semipalatinsk nuclear testing site.

    PubMed

    Taira, Yasuyuki; Hayashida, Naomi; Tsuchiya, Rimi; Yamaguchi, Hitoshi; Takahashi, Jumpei; Kazlovsky, Alexander; Urazalin, Marat; Rakhypbekov, Tolebay; Yamashita, Shunichi; Takamura, Noboru

    2013-01-01

    For the current on-site evaluation of the environmental contamination and contributory external exposure after the accident at the Chernobyl Nuclear Power Plant (CNPP) and the nuclear tests at the Semipalatinsk Nuclear Testing Site (SNTS), the concentrations of artificial radionuclides in soil samples from each area were analyzed by gamma spectrometry. Four artificial radionuclides ((241)Am, (134)Cs, (137)Cs, and (60)Co) were detected in surface soil around CNPP, whereas seven artificial radionuclides ((241)Am, (57)Co, (137)Cs, (95)Zr, (95)Nb, (58)Co, and (60)Co) were detected in surface soil around SNTS. Effective doses around CNPP were over the public dose limit of 1 mSv/y (International Commission on Radiological Protection, 1991). These levels in a contaminated area 12 km from Unit 4 were high, whereas levels in a decontaminated area 12 km from Unit 4 and another contaminated area 15 km from Unit 4 were comparatively low. On the other hand, the effective doses around SNTS were below the public dose limit. These findings suggest that the environmental contamination and effective doses on the ground definitely decrease with decontamination such as removing surface soil, although the effective doses of the sampling points around CNPP in the present study were all over the public dose limit. Thus, the remediation of soil as a countermeasure could be an extremely effective method not only for areas around CNPP and SNTS but also for areas around the Fukushima Dai-ichi Nuclear Power Plant (FNPP), and external exposure levels will be certainly reduced. Long-term follow-up of environmental monitoring around CNPP, SNTS, and FNPP, as well as evaluation of the health effects in the population residing around these areas, could contribute to radiation safety and reduce unnecessary exposure to the public. PMID:23469013

  14. Radon gas distribution in natural gas processing facilities and workplace air environment.

    PubMed

    Al-Masri, M S; Shwiekani, R

    2008-04-01

    Evaluation was made of the distribution of radon gas and radiation exposure rates in the four main natural gas treatment facilities in Syria. The results showed that radiation exposure rates at contact of all equipment were within the natural levels (0.09-0.1 microSvh(-1)) except for the reflex pumps where a dose rate value of 3 microSvh(-1) was recorded. Radon concentrations in Syrian natural gas varied between 15.4 Bq m(-3) and 1141 Bq m(-3); natural gas associated with oil production was found to contain higher concentrations than the non-associated natural gas. In addition, radon concentrations were higher in the central processing facilities than the wellheads; these high levels are due to pressurizing and concentrating processes that enhance radon gas and its decay products. Moreover, the lowest 222Rn concentration was in the natural gas fraction used for producing sulfur; a value of 80 Bq m(-3) was observed. On the other hand, maximum radon gas and its decay product concentrations in workplace air environments were found to be relatively high in the gas analysis laboratories; a value of 458 Bq m(-3) was observed. However, all reported levels in the workplaces in the four main stations were below the action level set by IAEA for chronic exposure situations involving radon, which is 1000 Bq m(-3). PMID:17905489

  15. A distributed code for color in natural scenes derived from center-surround filtered cone signals

    PubMed Central

    Kellner, Christian J.; Wachtler, Thomas

    2013-01-01

    In the retina of trichromatic primates, chromatic information is encoded in an opponent fashion and transmitted to the lateral geniculate nucleus (LGN) and visual cortex via parallel pathways. Chromatic selectivities of neurons in the LGN form two separate clusters, corresponding to two classes of cone opponency. In the visual cortex, however, the chromatic selectivities are more distributed, which is in accordance with a population code for color. Previous studies of cone signals in natural scenes typically found opponent codes with chromatic selectivities corresponding to two directions in color space. Here we investigated how the non-linear spatio-chromatic filtering in the retina influences the encoding of color signals. Cone signals were derived from hyper-spectral images of natural scenes and preprocessed by center-surround filtering and rectification, resulting in parallel ON and OFF channels. Independent Component Analysis (ICA) on these signals yielded a highly sparse code with basis functions that showed spatio-chromatic selectivities. In contrast to previous analyses of linear transformations of cone signals, chromatic selectivities were not restricted to two main chromatic axes, but were more continuously distributed in color space, similar to the population code of color in the early visual cortex. Our results indicate that spatio-chromatic processing in the retina leads to a more distributed and more efficient code for natural scenes. PMID:24098289

  16. A numerical study of liquid film distribution in wet natural gas pipelines

    NASA Astrophysics Data System (ADS)

    Gao, X. Q.; Zhao, Y. L.; Xu, W. W.; Guan, X. R.; Wang, J. J.; Jin, Y. H.

    2016-05-01

    The software of FLUENT was used to simulate the gas-liquid turbulent flow in wet natural gas pipeline of the Puguang gas field. The RNG k- ɛ model was used to simulate the turbulent flow, the Mixture model was used to simulate gas-liquid mixed phase, and the Eulerian wall film model was used to simulate the formation and development of liquid film. The gas phase flow field characteristics, the distribution of the axial and circumferential film thickness, and the droplet distribution in the pipeline were studied when the gas Reynolds number is 7.72 × 106(10.8m/s). The results can be concluded as followed: Liquid film distributes unevenly along the circumferential direction and mostly distributes under the pipeline wall because of gravity. The impact of the dean vortex and centrifugal force in the straight section can also influence the liquid film distribution. The wall shear stress distributions in horizontal straight pipeline is concerned with liquid membrane volatility, and consistent with the film volatility period, the wall shear stress reached the maximum value in a certain position of wave front. The influence of the wall shear stress on the film fluctuation in inclined pipeline is weakened by gravity and other factors.

  17. [The distribution and natural degradation of cyanide in goldmine waste-solid and polluted soil].

    PubMed

    Li, S; Zheng, B; Zhu, J; Wang, B

    2001-05-01

    The farmland and river were seriously polluted by cyanide because one goldmine tailing dam collapsed in 1995. 3 and 4 years after the accident, the cyanide distribution in the polluted farmland and the abandoned tailing dam was studied. The results indicated that natural degradation of cyanide in soil section was slower than in natural water body. The cyanide transference in soil section was similar to freely soluble salts. In arid and semiarid area, cyanide can be highly enriched in the salt shell which content degrading 4 years even higher than the fresh tailing slurry. One side the viscidity layer in the soil section can partly prevent cyanide transference to groundwater, on the other side the result can cause the cyanide highly enrich in the viscidity layer. According to character of cyanide natural degradation in soil the measurement of prevention and cure soil pollution by goldmine tailing dam collapsing was brought forward. PMID:11507898

  18. Power spectra and distribution of contrasts of natural images from different habitats.

    PubMed

    Balboa, Rosario M; Grzywacz, Norberto M

    2003-11-01

    Some theories for visual receptive fields postulate that they depend on the image statistics of the natural habitat. Consequently, different habitats may lead to different receptive fields. We thus decided to study how some of the most relevant statistics vary across habitats. In particular, atmospheric and underwater habitats were compared. For these habitats, we looked at two measures of the power spectrum and one of the distributions of contrasts. From power spectra, we analyzed the log-log slope of the fall and the degree of isotropy. From the distribution of contrasts, we analyzed the fall in a semi-log scale. Past studies found that the spatial power spectra of natural atmospheric images fall linearly in logarithmic axes with a slope of about -2 and that their distribution of contrasts shows an approximate linear fall in semi-logarithmic axes. Here, we show that the power spectrum of underwater images have statistically significantly steeper slopes ( approximately -2.5 in log-log axes) than atmospheric images. The vast majority of power spectra are non-isotropic, but their degree of anisotropy is extremely low, especially in atmospheric images. There are also statistical differences across habitats for the distribution of contrasts, with it falling faster for underwater images than for atmospheric ones. We will argue that these differences are due to the optical properties of water and that the differences have relevance for theories of visual receptive fields. These theories would predict larger receptive fields for aquatic animals compared to land animals. PMID:13129540

  19. Reverse-phase HPLC method for measuring polarity distributions of natural organic matter.

    PubMed

    Namjesnik-Dejanovic, Ksenija; Cabaniss, Stephen E

    2004-02-15

    A reverse-phase high-pressure liquid chromatography (RP-HPLC) method was developed to measure the polarity distribution of natural organic matter (NOM) samples. The polarity distribution is obtained by calibrating an octadecyl bonded silica phase column and polar eluent with compounds of known octanol-water partition coefficient (Kow) and using this calibration curve to transform NOM retention times into an equivalent Kow. Polarity distributions treat the NOM samples as a complex mixture rather than summarizing the polarity in a single number. The method is sensitive, with UV detection allowing quantitation of samples with <5 mg of C/L. Individual chromatograms are acquired in <20 min, allowing much faster analysis on smaller samples than XAD resin separation or 13C NMR. Polarity distributions of 10 representative NOM isolates and 2 whole water samples indicate that NOM is generally hydrophilic in nature (log Kow < 2), although XAD-8 isolates are more hydrophobic than RO isolates from the same source. Hydrophilicity, as indicated by recovery from the HPLC column, is correlated to the elemental oxygen/carbon ratio but does not correlate strongly with molecular weight or 13C NMR aromaticity. PMID:14998025

  20. On the lognormality of radionuclide deposition.

    PubMed

    Grubich, Andry

    2015-05-01

    The influence of the variation of soil density and the uncertainty of activity measurements on the statistical distribution of radionuclide concentrations on a site is considered. It is demonstrated that the influence of these factors adequately explains the observed deviation of radionuclide empirical probability distribution functions (empirical PDFs) from lognormal. In all probability lognormality of activity density distributions is the consequence of the atmospheric fallout process, as observed for deposition from Chernobyl and Fukushima. The results obtained are in no way specific to radioactive contaminants, and are consequently applicable for depositions of non-radioactive pollutants as well. PMID:25725453

  1. A globally distributed mobile genetic element inhibits natural transformation of Vibrio cholerae.

    PubMed

    Dalia, Ankur B; Seed, Kimberley D; Calderwood, Stephen B; Camilli, Andrew

    2015-08-18

    Natural transformation is one mechanism of horizontal gene transfer (HGT) in Vibrio cholerae, the causative agent of cholera. Recently, it was found that V. cholerae isolates from the Haiti outbreak were poorly transformed by this mechanism. Here, we show that an integrating conjugative element (ICE)-encoded DNase, which we name IdeA, is necessary and sufficient for inhibiting natural transformation of Haiti outbreak strains. We demonstrate that IdeA inhibits this mechanism of HGT in cis via DNA endonuclease activity that is localized to the periplasm. Furthermore, we show that natural transformation between cholera strains in a relevant environmental context is inhibited by IdeA. The ICE encoding IdeA is globally distributed. Therefore, we analyzed the prevalence and role for this ICE in limiting natural transformation of isolates from Bangladesh collected between 2001 and 2011. We found that IdeA(+) ICEs were nearly ubiquitous in isolates from 2001 to 2005; however, their prevalence decreased to ∼40% from 2006 to 2011. Thus, IdeA(+) ICEs may have limited the role of natural transformation in V. cholerae. However, the rise in prevalence of strains lacking IdeA may now increase the role of this conserved mechanism of HGT in the evolution of this pathogen. PMID:26240317

  2. Site Characterization for MNA of Radionuclides in Ground Water

    EPA Science Inventory

    Monitored natural attenuation is often evaluated as a component of the remedy for ground water contaminated with radionuclides. When properly employed, monitored natural attenuation (MNA) may provide an effective knowledge-based remedy where a thorough engineering analysis inform...

  3. Subsurface Characterization To Support Evaluation Of Radionuclide Transport And Attenuation

    EPA Science Inventory

    Remediation of ground water contaminated with radionuclides may be achieved using attenuation-based technologies. These technologies may rely on engineered processes (e.g., bioremediation) or natural processes (e.g., monitored natural attenuation) within the subsurface. In gene...

  4. Origin of artificial radionuclides in soil and sediment from North Wales.

    PubMed

    Al-Qasmi, Hamza; Law, Gareth T W; Fifield, L Keith; Livens, Francis R

    2016-01-01

    During the operations at the Sellafield nuclear fuel reprocessing complex, artificial radionuclides are discharged to the Irish Sea under authorisation, where they are dispersed. In this study, the southern distribution and transport of Sellafield derived radionuclides have been investigated. Both natural and artificial radionuclides have been studied in a soil core from the riverbank of the Afon Goch in Anglesey, North Wales. Particulate input is dominant for all artificial radionuclides (including the more soluble (137)Cs and (236)U) with an estimated lag time of about a decade. The preferential northward seawater movement in the NE Irish Sea limits solution input of (137)Cs and (236)U to the areas south of Sellafield. The relatively long lag time reflects both the water circulation pattern and distance between the study site in north Wales and the source point in Cumbria. Two redox active zones are observed in the top and the bottom of this core, although there is no evidence for any redistribution of Pu and natural uranium by these redox processes. However, (236)U, derived from irradiated uranium, showed variable distribution in the core. This could be a potential response to the geochemical conditions, showing that (236)U may be a promising tracer for the environmental processes and a signature of the Sellafield historical discharges of irradiated uranium. PMID:26529492

  5. Radionuclide bone imaging and densitometry

    SciTech Connect

    Mettler, F.A.

    1988-01-01

    This book contains 13 selections. Some of the titles are: Radionuclides and the Normal Bone Scan; The Radionuclide Bone Scan in Malignant Disease; Pediatric Applications of Radionuclide Bone Imaging; The Radionuclide Bone Scan in Arthritis and Metabolic and Miscellaneous Disorders; and Soft Tissue Activity on the Radionuclide Bone Scan.

  6. Natural gas transmission and distribution model of the National Energy Modeling System

    SciTech Connect

    1997-02-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA`s modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes.

  7. Distribution and environmental significance of nitrite-dependent anaerobic methane-oxidising bacteria in natural ecosystems.

    PubMed

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu

    2015-01-01

    Nitrite-dependent anaerobic methane oxidation (N-DAMO) is a recently discovered process that is performed by "Candidatus Methylomirabilis oxyfera" (M. oxyfera). This process constitutes a unique association between the two major global elements essential to life, carbon and nitrogen, and may act as an important and overlooked sink of the greenhouse gas methane. In recent years, more and more studies have reported the distribution of M. oxyfera-like bacteria and the occurrence of N-DAMO process in different natural ecosystems, including freshwater lakes, rivers, wetlands and marine ecosystems. Previous studies have estimated that a total of 2%-6% of current worldwide methane flux in wetlands could be consumed via the N-DAMO process. These findings indicate that N-DAMO is indeed a previously overlooked methane sink in natural ecosystems. Given the worldwide increase in anthropogenic nitrogen pollution, the N-DAMO process as a methane sink in reducing global warming could become more important in the future. The present mini-review summarises the current knowledge of the ecological distribution of M. oxyfera-like bacteria and the potential importance of the N-DAMO process in reducing methane emissions in various natural ecosystems. The potential influence of environmental factors on the N-DAMO process is also discussed. PMID:25398284

  8. The Influence of Hydrothermal Plumes on the Distribution of Anthropogenic Radionuclides Between the Particulate and Dissolved Phases: Results from U.S. Geotraces Equatorial Pacific Zonal Transect GP16

    NASA Astrophysics Data System (ADS)

    Kenna, T. C.; Villa Alfageme, M.; Casacuberta Arola, N.; Masque, P.

    2014-12-01

    Here we present and discuss the results from the analysis of samples from selected stations collected on the US GEOTRACES Equatorial Pacific Zonal Transect (GP16) completed in 2013. The section, between Peru and Tahiti, encompasses a range of processes that influence the supply, removal, and internal cycling of trace metals and offers the opportunity to gain a better understanding of the drivers of the transport and fate of contaminants in the ocean. The capability to analyze water and filtered particulate samples in the quantities available, allows us to determine the partitioning of selected radionuclides among dissolved and particulate forms (Kd) and estimate Pu-particulate fluxes. The overarching objective of our work is to determine the concentrations of several anthropogenic radionuclides, including 239Pu, 240Pu, 237Np, and 137Cs with sufficient resolution to define their basin-wide distributions in the Pacific Ocean. Data collected in the East Pacific Rise hydrothermal plume allows a discussion on the partitioning behavior of plutonium and neptunium.

  9. Model documentation Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1996-02-26

    The Natural Gas Transmission and Distribution Model (NGTDM) of the National Energy Modeling System is developed and maintained by the Energy Information Administration (EIA), Office of Integrated Analysis and Forecasting. This report documents the archived version of the NGTDM that was used to produce the natural gas forecasts presented in the Annual Energy Outlook 1996, (DOE/EIA-0383(96)). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic approach, and provides detail on the methodology employed. Previously this report represented Volume I of a two-volume set. Volume II reported on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.

  10. The distribution of the dark matter in galaxies as the imprint of its Nature

    NASA Astrophysics Data System (ADS)

    Frigerio Martins, Christiane

    2009-03-01

    The standard framework within which cosmological measurements are confronted and interpreted nowadays, called Lambda Cold Dark Matter, presents a Universe dominated by unknown forms of energy and matter. My Thesis is devoted to investigate the distribution of dark matter in galaxies and addresses the fact that the local universe-the small objects that orbit galaxies and the galaxy cores-turns out to be a marvelous laboratory for examining the nature of dark matter and the fundamental physics involved in structure formation and evolution. I develop tests, based on mass modeling of rotation curves, for the validation of dark matter models on galactic scales. These tests have been applied in analyzing the phenomenology of the cusp vs core controversy, and the phenomenon of non-Keplerian rotation curves as modification of the laws of gravity. I further investigate the properties and scaling laws of dark matter halos. My conclusion is that galactic observations provide strong imprints on the nature of dark matter.

  11. The return period analysis of natural disasters with statistical modeling of bivariate joint probability distribution.

    PubMed

    Li, Ning; Liu, Xueqin; Xie, Wei; Wu, Jidong; Zhang, Peng

    2013-01-01

    New features of natural disasters have been observed over the last several years. The factors that influence the disasters' formation mechanisms, regularity of occurrence and main characteristics have been revealed to be more complicated and diverse in nature than previously thought. As the uncertainty involved increases, the variables need to be examined further. This article discusses the importance and the shortage of multivariate analysis of natural disasters and presents a method to estimate the joint probability of the return periods and perform a risk analysis. Severe dust storms from 1990 to 2008 in Inner Mongolia were used as a case study to test this new methodology, as they are normal and recurring climatic phenomena on Earth. Based on the 79 investigated events and according to the dust storm definition with bivariate, the joint probability distribution of severe dust storms was established using the observed data of maximum wind speed and duration. The joint return periods of severe dust storms were calculated, and the relevant risk was analyzed according to the joint probability. The copula function is able to simulate severe dust storm disasters accurately. The joint return periods generated are closer to those observed in reality than the univariate return periods and thus have more value in severe dust storm disaster mitigation, strategy making, program design, and improvement of risk management. This research may prove useful in risk-based decision making. The exploration of multivariate analysis methods can also lay the foundation for further applications in natural disaster risk analysis. PMID:22616629

  12. Sedimentary organic matter distributions, burrowing activity, and biogeochemical cycling: Natural patterns and experimental artifacts

    NASA Astrophysics Data System (ADS)

    Michaud, Emma; Aller, Robert, C.; Stora, Georges

    2010-11-01

    The coupling between biogenic reworking activity and reactive organic matter patterns within deposits is poorly understood and often ignored. In this study, we examined how common experimental treatments of sediment affect the burrowing behavior of the polychaete Nephtys incisa and how these effects may interact with reactive organic matter distributions to alter diagenetic transport - reaction balances. Sediment and animals were recovered from a subtidal site in central Long Island Sound, USA. The upper 15 cm of the sediment was sectioned into sub-intervals, and each interval separately sieved and homogenized. Three initial distributions of sediment and organic substrate reactivity were setup in a series of microcosms: (1) a reconstituted natural pattern with surface-derived sediment overlying sediment obtained from progressively deeper material to a depth of 15 cm (Natural); (2) a 15 cm thick sediment layer composed only of surface-derived sediment (Rich); and (3) a 15 cm thick layer composed of uniformally mixed sediment from the original 15 cm sediment profile (Averaged). The two last treatments are comparable to that used in microcosms in many previous studies of bioturbation and interspecific functional interaction experiments. Sediment grain size distributions were 97.5% silt-clay and showed no depth dependent patterns. Sediment porosity gradients were slightly altered by the treatments. Nepthys were reintroduced and aquariums were X-rayed regularly over 5 months to visualize and quantify spatial and temporal dynamics of burrows. The burrowing behaviour of adult populations having similar total biovolume, biomass, abundance, and individual sizes differed substantially as a function of treatment. Burrows in sediment with natural property gradients were much shallower and less dense than those in microcosms with altered gradients. The burrow volume/biovolume ratio was also lower in the substrate with natural organic reactivity gradients. Variation in food

  13. Marine plankton as an indicator of low-level radionuclide contamination in the Southern Ocean

    SciTech Connect

    Marsh, K.V.; Buddemeier, R.W.

    1984-07-01

    We have initiated an investigation of the utility of marine plankton as bioconcentrating samplers of low-level marine radioactivity in the southern hemisphere. A literature review shows that both freshwater and marine plankton have trace element and radionuclide concentration factors (relative to water) of up to 10/sup 4/. In the years 1956-1958, considerable work was done on the accumulation and distribution of a variety of fission and activation products produced by the nuclear tests in the Marshall Islands. Since then, studies have largely been confined to a few selected radionuclides, and by far most of this work has been done in the northern hemisphere. We participated in Operation Deepfreeze 1981, collecting 32 plankton samples from the U.S. Coast Guard Cutter Glacier on its Antarctic cruise, while Battelle Pacific Northwest Laboratories concurrently sampled air, water, rain and fallout. We were able to measure concentrations of the naturally occurring radionuclides /sup 7/Be, /sup 40/K and the U and th series, and we believe that we have detected low levels of /sup 144/Ce and /sup 95/Nb in seven samples ranging as far south as 68/sup 0/. There is a definite association between the radionuclide content of plankton and air filters, suggesting that aerosol resuspension of marine radioactivity may be occurring. Biological identification of the plankton suggests a possible correlation between radionuclide concentration and foraminifera content of the samples. 38 references, 7 figures, 3 tables.

  14. Imaging distributed and massed repetitions of natural scenes: Spontaneous retrieval and maintenance

    PubMed Central

    Bradley, Margaret M.; Costa, Vincent D.; Ferrari, Vera; Codispoti, Maurizio; Fitzsimmons, Jeffrey R.; Lang, Peter J.

    2015-01-01

    Repetitions that are distributed (spaced) across time prompt enhancement of a memory-related event-related potential, compared to when repetitions are massed (contiguous). Here, we employed fMRI to investigate neural enhancement and suppression effects during free viewing of natural scenes that were either novel or repeated four times with massed or distributed repetitions. Distributed repetition was uniquely associated with a repetition enhancement effect in a bilateral posterior parietal cluster that included the precuneus and posterior cingulate and which has previously been implicated in episodic memory retrieval. Unique to massed repetition, on the other hand, was enhancement in a right dorsolateral prefrontal cluster that has been implicated in short-term maintenance. Repetition suppression effects for both types of spacing were widespread in regions activated during novel picture processing. Taken together, the data are consistent with a hypothesis that distributed repetition prompts spontaneous retrieval of prior occurrences, whereas massed repetitions prompts short-term maintenance of the episodic representation, due to contiguous presentation. These processing differences may mediate the classic spacing effect in learning and memory. PMID:25504854

  15. Reactor-released radionuclides in Susquehanna River sediments

    USGS Publications Warehouse

    Olsen, C.R.; Larsen, I.L.; Cutshall, N.H.; Donoghue, J.F.; Bricker, O.P.; Simpson, H.J.

    1981-01-01

    Three Mile Island (TMI) and Peach Bottom (PB) reactors have introduced 137Cs, 134Cs, 60Co, 58Co and several other anthropogenic radionuclides into the lower Susquehanna River. Here we present the release history for these nuclides (Table 1) and radionuclide concentration data (Table 2) for sediment samples collected in the river and upper portions of the Chesapeake Bay (Fig. 1) within a few months after the 28 March 1979 loss-of-coolant-water problem at TMI. Although we found no evidence for nuclides characteristic of a ruptured fuel element, we did find nuclides characteristic of routine operations. Despite the TMI incident, more than 95% of the total 134Cs input to the Susquehanna has been a result of controlled low-level releases from the PB site. 134Cs activity released into the river is effectively trapped by sediments with the major zones of reactor-nuclide accumulation behind Conowingo Dam and in the upper portions of Chesapeake Bay. The reported distributions document the fate of reactor-released radionuclides and their extent of environmental contamination in the Susquehanna-Upper Chesapeake Bay System. ?? 1981 Nature Publishing Group.

  16. Radionuclides in haematology

    SciTech Connect

    Lewis, S.M.; Bayly, R.J.

    1986-01-01

    This book contains the following chapters: Some prerequisites to the use of radionuclides in haematology; Instrumentation and counting techniques; In vitro techniques; Cell labelling; Protein labelling; Autoradiography; Imaging and quantitative scanning; Whole body counting; Absorption and excretion studies; Blood volume studies; Plasma clearance studies; and Radionuclide blood cell survival studies.

  17. Diversity, natural history, and geographic distribution of snakes in the Caatinga, Northeastern Brazil.

    PubMed

    Guedes, Thaís B; Nogueira, Cristiano; Marques, Otavio A V

    2014-01-01

    The present study is a synthesis on snake diversity and distribution in the Caatinga region of northeastern Brazil, providing an updated species list and data on natural history and geographic distribution. Our study is based on the careful revision of 7,102 voucher specimens, housed in 17 herpetological collections, complemented by data on taxonomic literature. We recorded a total of 112 snake species in the Caatinga, belonging to nine families: Anomalepididae, Leptotyphlopidae, Typhlopidae, Aniliidae, Boidae, Viperidae, Elapidae, Colubridae, and Dipsadidae. Our list includes at least 13 never recorded species for this region, as well as distribution records for all species known from the Caatinga (including expansion and new records of distribution). The snake assemblage of the Caatinga is complex, sharing species with other continental open areas (38.4%), forested areas (27.7%), and both open and forested areas (32.1%). The richest areas were isolated plateaus, followed by contact areas, semi-arid caatinga, and sandy dunes of the São Franscisco River. We identified 22 Caatinga endemic species with the sandy dunes of São Franscico River showing the highest endemism level (12 species, with six endemic species restricted to the area) followed by semi-arid caatinga, and isolated plateaus (eight endemic species each, and six and three endemic species with restricted distribution to each area, respectively). Most species show relatively restricted ranges in parts of the Caatinga. The snake assemblage in Caatinga includes mainly terrestrial species (38.4%), followed by fossorial/cryptozoic (26.8%), arboreal/semi-arboreal (26.8%), and aquatic/semi-aquatic (7.1%) species. Vertebrates are the most important dietary item (80.4%), with 56.6% of species being generalist consumers of this kind of prey; 24.4% are frog-eaters, 7.8% prey on caecilians/amphisbaenians, 6.7% lizard-eaters, 3.3% mammal-eaters, and 1.1% are fish-eaters. Only 18.7% of the snakes eat invertebrate

  18. Environmental consequences of postulated radionuclide releases from the Battelle Memorial Institute Columbus Laboratories JN-1b Building at the West Jefferson site as a result of severe natural phenomena

    SciTech Connect

    Jamison, J.D.; Watson, E.C.

    1982-02-01

    Potential environmental consequences in terms of radiation dose to people are presented for postulated radionuclide releases caused by severe natural phenomena at the Battelle Memorial Institute Columbus Laboratories JN-1b Building at the West Jefferson site. The severe natural phenomena considered are earthquakes, tornadoes, and high straight-line winds. Maximum radioactive material deposition values are given for significant locations around the site. All important potential exposure pathways are examined. The most likely 50-year committed dose equivalents are given for the maximum-exposed individual and the population within a 50-mile radius of the plant. The maximum radioactive material deposition values likely to occur offsite are also given. The most likely calculated 50-year collective committed dose equivalents are all much lower than the collective dose equivalent expected from 50 years of exposure to natural background radiation and medical x-rays. The most likely maximum residual plutonium contamination estimated to be deposited offsite following the events are well below the Environmental Protection Agency's (EPA) proposed guideline for plutonium in the general environment of 0.2 ..mu..Ci/m/sup 2/. The likely maximum residual contamination from beta and gamma emitters are far below the background produced by fallout from nuclear weapons tests in the atmosphere.

  19. State of radionuclides in soils of the eastern-urals radioactive trace

    SciTech Connect

    Martyushov, V.V.; Spirin, D.A.; Bazylev, V.V.

    1995-03-01

    Data on the distribution of long-living radionuclides in a 0-30-cm layer of different types of soils, contaminated as a result of the accident in 1957, are given. Forms of the state and existence of radionuclides in soils are considered in detail. It was determined that distribution of radionuclides and forms of their state and whereabouts in soils depend both on the properties of radionuclides and on soil type.

  20. Fe-Mn substance in ocean as reason of regulation radionuclide pollution

    NASA Astrophysics Data System (ADS)

    Asavin, Alex; Martynov, Konstantin; Konstantinova, Lia

    2013-04-01

    Distribution of radionuclide in marine sediments as yet little studied [Choppin & Wong 1998]. The work mainly focused on effects of nuclear test fallout. In the works are examined isotopes of Pu - 238; Th - 232; U -234;238; Pu - 239,240,241; Am - 241; Np - 237; Cm -244 [Holm 1995]. It has been shown that seems to accumulate radionuclides in marine sediments. In particular, the importance attached to carbonate complexes (corals, etc.). But questions about the possibility of re-mobilization of radionuclide, forms their concentration, their participation in global geochemical cycles in the ocean, remain open. We believe a major factor controlling the distribution of heavy metals is the formation of ocean ferromanganese crusts and nodules hydrogenic at the bottom of the ocean and seamounts. It is likely that the process of formation of Fe-manganese hydrogenic can play a major role in the control of radioactive contamination in the oceanic sediment. At least for the U number of works on the subject [Sherman et al. 2008]. The high sensitivity of the Fe-manganese crust is known to the isotopic composition of lead [Loranger & Zayed 1994, Collen et al 2011]. Recent work [Wilkins etal 2006, Renshaw etal 2009] show a large role; Fe (III)-and Mn (IV)-reducing organisms that anaerobic bacteria in oxidation and therefore changes in mobility systems U and Pu. So much interest is data for sorption of radionuclide on hydroxides Fe and Mn. Unfortunately we are not aware of works on the subject. We have therefore taken their own experimental studies on sorption of radionuclide on natural Fe-Mn crusts (sample from Magellan seamount Pacific ocean) [Martynov et al 2012]. The results showed high sorption ability of material crusts for fixation of radionuclides: U-233, Np-237, Pu-238, Am-241. For all radionuclide experiment absorption has been reached already in the first hour it was 96.0% of total substance radionuclide absorbed from the solution, and after the first day it was reached

  1. Model documentation: Natural Gas Transmission and Distribution Model of the National Energy Modeling System; Volume 1

    SciTech Connect

    1994-02-24

    The Natural Gas Transmission and Distribution Model (NGTDM) is a component of the National Energy Modeling System (NEMS) used to represent the domestic natural gas transmission and distribution system. NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the Energy Information Administration (EIA) and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. This report documents the archived version of NGTDM that was used to produce the natural gas forecasts used in support of the Annual Energy Outlook 1994, DOE/EIA-0383(94). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. It is intended to fulfill the legal obligation of the EIA to provide adequate documentation in support of its models (Public Law 94-385, Section 57.b.2). This report represents Volume 1 of a two-volume set. (Volume 2 will report on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.) Subsequent chapters of this report provide: (1) an overview of the NGTDM (Chapter 2); (2) a description of the interface between the National Energy Modeling System (NEMS) and the NGTDM (Chapter 3); (3) an overview of the solution methodology of the NGTDM (Chapter 4); (4) the solution methodology for the Annual Flow Module (Chapter 5); (5) the solution methodology for the Distributor Tariff Module (Chapter 6); (6) the solution methodology for the Capacity Expansion Module (Chapter 7); (7) the solution methodology for the Pipeline Tariff Module (Chapter 8); and (8) a description of model assumptions, inputs, and outputs (Chapter 9).

  2. Development of heterogeneity in proppant distribution due to engineered and natural processes during hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Morris, J.; Roy, P.; Walsh, S.

    2015-12-01

    Proppant, such as sand, is injected during hydraulic fracturing to maintain fracture aperture and conductivity. Proppant performance is a complex result of fluid flow, discrete particle mechanics and geomechanical deformation. We present investigations into these phenomena at scales ranging from millimeters to meters. Traditionally, the design goal for proppant placement is uniform distribution by using viscous carrier fluids that keep the proppant suspended and maintain conductivity over the full area of the fracture. Large volume hydraulic fracturing in shales typically use low viscosity fluids, resulting in proppant settling out from the carrier fluid. Consequently, the proppant occupies the lower portion of the fracture. In addition, many shale plays host natural fractures that take up injected carrier fluid, but may not develop sufficient aperture to accommodate proppant. We present simulations investigating natural development of heterogeneity in proppant distribution within fracture networks due to settling and network flow. In addition to natural development of heterogeneity, the petroleum industry has sought to engineer heterogeneity to generate isolated propped portions of the fracture that maintain aperture in adjacent, open channels. We present two examples of such heterogeneous proppant placement (HPP) technologies. The first involves pulsating proppant at the wellhead and the second utilizes a homogenous composite fluid that develops heterogeneity spontaneously through hydrodynamic instabilities. We present simulation results that compare these approaches and conclude that spontaneous creation of heterogeneity has distinct geomechanical advantages. Finally, we present simulations at the scale of individual proppant particles that emphasize the complexity of dynamic instabilities and their influence upon proppant fate. Disclaimer: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under

  3. Challenging the Concept of Natural Distributions: Global Change Turns Trees Into Weeds

    NASA Astrophysics Data System (ADS)

    Gleadow, R.; O'Leary, B.; Burd, M.

    2015-12-01

    National parks and nature reserves are set aside to preserve certain ecosystems, reflecting species distributions at a moment in time. Changing climate and fire dynamics can mean that the species most suited to that area are different, leading new tree species to 'invade' the conservation areas. Pittosporum undulatum is an invasive tree native tree species with a natural range from southeast Queensland to Eastern Victoria, Australia. Soon after European settlement this species became a popular ornamental tree in gardens and was planted outside of its natural range across the continent and introduced to the USA (where it is known as Victorian Box), the Hawaiian Islands, Jamaica, southern Africa and the Azores. The reason this is important is because high density of P. undulatum lead to reduced biodiversity and often the complete suppression of regeneration of exiting forest trees. In Australia, changes in fire dynamics have played a major part in its in dominance. New strategies for forest management were proposed by Gleadow an Ashton in the 1980s, but lack of action has led us to predict that the entire Dandenong Ranges, near Melbourne, will be invaded within 25 years resulting in the loss of a major recreational and conservation area. This is a model of the type of problems that can be expected as the climate envelope for species changes in the coming century, challenging the very concept of a "native ".

  4. Large scale distribution of dioxins, PCBs, heavy metals, PAH-metabolites and radionuclides in cod (Gadus morhua) from the North Atlantic and its adjacent seas.

    PubMed

    Karl, Horst; Kammann, Ulrike; Aust, Marc-Oliver; Manthey-Karl, Monika; Lüth, Anja; Kanisch, Günter

    2016-04-01

    Regarding cod as sea food for human consumption and as bio indicator of the marine eco system, this study is the first approach to combine the analysis of organic and inorganic contaminants and radionuclides in cod muscle as well as PCDD/Fs and dl-PCBs in its livers from the same fishing areas. Concentrations of 1-hydroxypyrene, PCDD/Fs, PCBs, cesium-137 (Cs-137), cadmium and lead were determined in individual or pooled samples over a wide geographic area, including Greenland Seas, Barents Sea, North and Baltic Sea. Highest concentrations were found in samples from the Baltic Sea, lowest in the pristine areas of the Barents Sea and Greenland. Levels of contaminants in cod muscle were found to be far below the established EU maximum levels (ML), regardless of which fishing grounds. In contrast to this, most cod liver samples from the North and Baltic Sea showed PCDD/F and PCB contents exceeding the ML. In addition, new background assessment criteria (BAC) for 1-hydroxypyrene in cod of 4.6 ng mL(-1) bile and for Cs-137 a BAC of 0.16 Bq kg(-1) wet weight are proposed to be included in the European Marine Strategy Framework Directive for cod from the Northeast Atlantic. PMID:26874057

  5. Direct measurements show decreasing methane emissions from natural gas local distribution systems in the United States.

    PubMed

    Lamb, Brian K; Edburg, Steven L; Ferrara, Thomas W; Howard, Touché; Harrison, Matthew R; Kolb, Charles E; Townsend-Small, Amy; Dyck, Wesley; Possolo, Antonio; Whetstone, James R

    2015-04-21

    Fugitive losses from natural gas distribution systems are a significant source of anthropogenic methane. Here, we report on a national sampling program to measure methane emissions from 13 urban distribution systems across the U.S. Emission factors were derived from direct measurements at 230 underground pipeline leaks and 229 metering and regulating facilities using stratified random sampling. When these new emission factors are combined with estimates for customer meters, maintenance, and upsets, and current pipeline miles and numbers of facilities, the total estimate is 393 Gg/yr with a 95% upper confidence limit of 854 Gg/yr (0.10% to 0.22% of the methane delivered nationwide). This fraction includes emissions from city gates to the customer meter, but does not include other urban sources or those downstream of customer meters. The upper confidence limit accounts for the skewed distribution of measurements, where a few large emitters accounted for most of the emissions. This emission estimate is 36% to 70% less than the 2011 EPA inventory, (based largely on 1990s emission data), and reflects significant upgrades at metering and regulating stations, improvements in leak detection and maintenance activities, as well as potential effects from differences in methodologies between the two studies. PMID:25826444

  6. Distribution and natural history of stress fractures in U. S. Marine recruits

    SciTech Connect

    Greaney, R.B.; Gerber, F.H.; Laughlin, R.L.; Kmet, J.P.; Metz, C.D.; Kilcheski, T.S.; Rao, B.R.; Silverman, E.D.

    1983-02-01

    In a prospective study of stress injuries of the lower extremities of U.S. Marine recruits, researchers derived a frequency distribution of stress fractures. The most frequently fractured bone was the tibia (73%), while the single most common site was the posterior calcaneal tuberosity (21%). The natural history of stress fractures by scintigraphy and radiography has been outlined, showing the evolutionary changes on either study as a universal progression independent of injury site or type of stress. An identical spectrum of changes should be present within any group undergoing intense new exercise. The frequency distribution of stress fractures should be a function of differing forms and intensities of exercise, therefore, our figures should not be applied to other groups. Researchers used the presence of a scintigraphic abnormality at a symptomatic site as the criterion for diagnosis of stress fracture. Since the distribution of skeletal radiotracer uptake is directly dependent on local metabolic activity, it is expected that a focal alteration in bone metabolism will result in a scintigram approaching 100% sensitivity for the abnormality (9). In the proper clinical setting, the specificity should approximate this figure; however, a focal, nonstress-related bone abnormality which has not manifested any radiographic change, such as early osteomyelitis, could result in a false-positive examination. Specificity cannot, therefore, be accurately determined without an actual determination of the pathologic changes within the bone, necessarily involving biopsy.

  7. Distribution and Abundance of Insertion Sequences among Natural Isolates of Escherichia coli

    PubMed Central

    Sawyer, Stanley A.; Dykhuizen, Daniel E.; DuBose, Robert F.; Green, Louis; Mutangadura-Mhlanga, T.; Wolczyk, David F.; Hartl, Daniel L.

    1987-01-01

    A reference collection of 71 natural isolates of Escherichia coli (the ECOR collection) has been studied with respect to the distribution and abundance of transposable insertion sequences using DNA hybridization. The data include 1173 occurrences of six unrelated insertion sequences (IS 1, IS2, IS3, IS4, IS5 and IS 30). The number of insertion elements per strain, and the sizes of DNA restriction fragments containing them, is highly variable and can be used to discriminate even among closely related strains. The occurrence and abundance of pairs of unrelated insertion sequences are apparently statistically independent, but significant correlations result from stratifications in the reference collection. However, there is a highly significant positive association among the insertion sequences considered in the aggregate. Nine branching process models, which differ in assumptions regarding the regulation of transposition and the effect of copy number on fitness, have been evaluated with regard to their fit of the observed distributions. No single model fits all copy number distributions. The best models incorporate no regulation of transposition and a moderate to strong decrease in fitness with increasing copy number for IS1 and IS5, strong regulation of transposition and a negligible to weak decrease in fitness with increasing copy number for IS3, and less than strong regulation of transposition for IS2, IS 4 and IS30. PMID:3030884

  8. Critical review: Radionuclide transport, sediment transport, and water quality mathematical modeling; and radionuclide adsorption/desorption mechanisms

    SciTech Connect

    Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L.

    1981-01-01

    This report describes the results of a detailed literature review of radionuclide transport models applicable to rivers, estuaries, coastal waters, the Great Lakes, and impoundments. Some representatives sediment transport and water quality models were also reviewed to evaluate if they can be readily adapted to radionuclide transport modeling. The review showed that most available transport models were developed for dissolved radionuclide in rivers. These models include the mechanisms of advection, dispersion, and radionuclide decay. Since the models do not include sediment and radionuclide interactions, they are best suited for simulating short-term radionuclide migration where: (1) radionuclides have small distribution coefficients; (2) sediment concentrations in receiving water bodies are very low. Only 5 of the reviewed models include full sediment and radionuclide interactions: CHMSED developed by Fields; FETRA SERATRA, and TODAM developed by Onishi et al, and a model developed by Shull and Gloyna. The 5 models are applicable to cases where: (1) the distribution coefficient is large; (2) sediment concentrations are high; or (3) long-term migration and accumulation are under consideration. The report also discusses radionuclide absorption/desorption distribution ratios and addresses adsorption/desorption mechanisms and their controlling processes for 25 elements under surface water conditions. These elements are: Am, Sb, C, Ce, Cm, Co, Cr, Cs, Eu, I, Fe, Mn, Np, P, Pu, Pm, Ra, Ru, Sr, Tc, Th, {sup 3}H, U, Zn and Zr.

  9. Influence of basalt/groundwater interactions on radionuclide migration

    SciTech Connect

    Vandegrift, G.F.

    1984-01-01

    The work presented here is a partial summary of the experimental results obtained in the Laboratory Analog Program. Two aspects of this effort are (1) the interaction between simulated basaltic groundwater and basalt fissures that were either freshly cleaved or laboratory altered by hydrothermal treatment with the simulated groundwater and (2) the effect of this interaction on radionuclide migration through these basalt fissures. The following conclusions of this study bear heavily on the predicted safety of a basalt repository: Sorption properties of freshly fissured basalt and naturally aged basalt are quite different for different chemical species. Analog experiments predict that aged basalt would be an effective retarder of cesium, but would be much less so for actinide elements. Distribution ratios measured from batch experiments with finely ground rock samples (presenting unaltered rock surfaces) are not a reliable means of predicting radionuclide migration in geological repositories. As the near-repository area is resaturated by groundwater, its ability to retard actinide migration will be degraded with time. Disturbing the natural flow of groundwater through the repository area by constructing and backfilling the repository will modify the composition of groundwater. This modified groundwater is likely to interact with and to modify naturally aged basalt surfaces downstream from the repository.

  10. Probability distributions of whisker-surface contact: quantifying elements of the rat vibrissotactile natural scene.

    PubMed

    Hobbs, Jennifer A; Towal, R Blythe; Hartmann, Mitra J Z

    2015-08-01

    Analysis of natural scene statistics has been a powerful approach for understanding neural coding in the auditory and visual systems. In the field of somatosensation, it has been more challenging to quantify the natural tactile scene, in part because somatosensory signals are so tightly linked to the animal's movements. The present work takes a step towards quantifying the natural tactile scene for the rat vibrissal system by simulating rat whisking motions to systematically investigate the probabilities of whisker-object contact in naturalistic environments. The simulations permit an exhaustive search through the complete space of possible contact patterns, thereby allowing for the characterization of the patterns that would most likely occur during long sequences of natural exploratory behavior. We specifically quantified the probabilities of 'concomitant contact', that is, given that a particular whisker makes contact with a surface during a whisk, what is the probability that each of the other whiskers will also make contact with the surface during that whisk? Probabilities of concomitant contact were quantified in simulations that assumed increasingly naturalistic conditions: first, the space of all possible head poses; second, the space of behaviorally preferred head poses as measured experimentally; and third, common head poses in environments such as cages and burrows. As environments became more naturalistic, the probability distributions shifted from exhibiting a 'row-wise' structure to a more diagonal structure. Results also reveal that the rat appears to use motor strategies (e.g. head pitches) that generate contact patterns that are particularly well suited to extract information in the presence of uncertainty. PMID:26290591

  11. Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape.

    PubMed

    Andraski, B J; Jackson, W A; Welborn, T L; Böhlke, J K; Sevanthi, Ritesh; Stonestrom, D A

    2014-05-01

    Perchlorate (ClO) is a contaminant that occurs naturally throughout the world, but little is known about its distribution and interactions in terrestrial ecosystems. The objectives of this Amargosa Desert, Nevada study were to determine (i) the local-scale distribution of shallow-soil (0-30 cm) ClO with respect to shrub proximity (far and near) in three geomorphic settings (shoulder slope, footslope, and valley floor); (ii) the importance of soil, plant, and terrain variables on the hillslope-distribution of shallow-soil and creosote bush [ (Sessé & Moc. ex DC.) Coville] ClO; and (iii) atmospheric (wet plus dry, including dust) deposition of ClO in relation to soil and plant reservoirs and cycling. Soil ClO ranged from 0.3 to 5.0 μg kg. Within settings, valley floor ClO was 17× less near shrubs due in part to enhanced leaching, whereas shoulder and footslope values were ∼2× greater near shrubs. Hillslope regression models (soil, = 0.42; leaf, = 0.74) identified topographic and soil effects on ClO deposition, transport, and cycling. Selective plant uptake, bioaccumulation, and soil enrichment were evidenced by leaf ClO concentrations and Cl/ClO molar ratios that were ∼8000× greater and 40× less, respectively, than soil values. Atmospheric deposition ClO flux was 343 mg ha yr, ∼10× that for published southwestern wet-deposition fluxes. Creosote bush canopy ClO (1310 mg ha) was identified as a previously unrecognized but important and active reservoir. Nitrate δO analyses of atmospheric deposition and soil supported the leaf-cycled-ClO input hypothesis. This study provides basic data on ClO distribution and cycling that are pertinent to the assessment of environmental impacts in desert ecosystems and broadly transferable to anthropogenically contaminated systems. PMID:25602827

  12. Mathematical Simulation of Sediment and Radionuclide Transport in Surface Waters

    SciTech Connect

    ,

    1981-04-01

    The study objective of "The Mathematical Simulation of Sediment and Radionuclide Transport in Surface Waters" is to synthesize and test radionuclide transport models capable of realistically assessing radionuclide transport in various types of surface water bodies by including the sediment-radionuclide interactions. These interactions include radionuclide adsorption by sediment; desorption from sediment into water; and transport, deposition, and resuspension of sorbed radionuclides controlled by the sediment movements. During FY-1979, the modification of sediment and contaminant (radionuclide) transport model, FETRA, was completed to make it applicable to coastal waters. The model is an unsteady, two-dimensional (longitudinal and lateral) model that consists of three submodels (for sediment, dissolved-contaminant, and particulate-contaminant transport), coupled to include the sediment-contaminant interactions. In estuaries, flow phenomena and consequent sediment and radionuclide migration are often three-dimensional in nature mainly because of nonuniform channel cross-sections, salinity intrusion, and lateral-flow circulation. Thus, an unsteady, three-dimensional radionuclide transport model for estuaries is also being synthesized by combining and modifying a PNL unsteady hydrothermal model and FETRA. These two radionuclide transport models for coastal waters and estuaries will be applied to actual sites to examine the validity of the codes.

  13. Radionuclides in US coals

    SciTech Connect

    Bisselle, C. A.; Brown, R. D.

    1984-03-01

    The current state of knowledge with respect to radionuclide concentrations in US coals is discussed. Emphasis is placed on the levels of uranium in coal (and lignite) which are considered to represent a concern resulting from coal combustion; areas of the US where such levels have been found; and possible origins of high radionuclide levels in coal. The report reviews relevant studies and presents new data derived from a computerized search of radionuclide content in about 4000 coal samples collected throughout the coterminous US. 103 references, 5 figures, 5 tables.

  14. Cluster analysis of radionuclide concentrations in beach sand.

    PubMed

    de Meijer, R J; James, I R; Jennings, P J; Koeyers, J E

    2001-03-01

    This paper presents a method in which natural radionuclide concentrations of beach sand minerals are traced along a stretch of coast by cluster analysis. This analysis yields two groups of mineral deposit with different origins. The method deviates from standard methods of following dispersal of radionuclides in the environment, which are usually based on the construction of lines of equal concentrations. The paper focuses on the methodology of quantitatively correlating activity concentrations of natural radionuclides in two groups of minerals. The methodology is widely applicable, but is demonstrated for natural radioactivity in beach sands along the coast of South West Australia. PMID:11214891

  15. Chancellor Water Colloids: Characterization and Radionuclide Association

    SciTech Connect

    Abdel-Fattah, Amr I.

    2012-06-18

    Concluding remarks about this paper are: (1) Gravitational settling, zeta potential, and ultrafiltration data indicate the existence of a colloidal phase of both the alpha and beta emitters in the Chancellor water; (2) The low activity combined with high dispersion homogeneity of the Chancellor water indicate that both alpha and beta emitters are not intrinsic colloids; (3) Radionuclides in the Chancellor water, particularly Pu, coexist as dissolved aqueous and sorbed phases - in other words the radionuclides are partitioned between the aqueous phase and the colloidal phase; (4) The presence of Pu as a dissolved species in the aqueous phase, suggests the possibility of Pu in the (V) oxidation state - this conclusion is supported by the similarity of the k{sub d} value of Pu determined in the current study to that determined for Pu(V) sorbed onto smectite colloids, and the similar electrokinetic behavior of the Chancellor water colloids to smectite colloids; (5) About 50% of the Pu(V) is in the aqueous phase and 50% is sorbed on colloids (mass concentration of colloids in the Chancellor water is 0.12 g/L); (6) The k{sub d} of the Pu and the beta emitters (fission products) between aqueous and colloidal phases in the Chancellor water is {approx}8.0 x 10{sup 3} mL/g using two different activity measurement techniques (LSC and alpha spectroscopy); (7) The gravitational settling and size distributions of the association colloids indicate that the properties (at least the physical ones) of the colloids to which the alpha emitters are associated with seem to be different that the properties of the colloids to which the beta emitters are associated with - the beta emitters are associated with very small particles ({approx}50 - 120 nm), while the alpha emitters are associated with relatively larger particles; and (8) The Chancellor water colloids are extremely stable under the natural pH and ionic strength conditions, indicating high potential for transport in the

  16. [The level of DNA damage and DNA reparation rate in cells of earthworms sampled from natural populations for numerous generations inhabited territories with anthropogenically enhanced levels of radionuclides in soil].

    PubMed

    Kaneva, A V; Belykh, E S; Maystrenko, T A; Shadrin, D M; Pylina, Ya I; Velegzhaninov, I O

    2015-01-01

    Low doses of ionizing radiation and chemical toxic agent effects on biological systems on different organization levels have been studied by numerous researchers. But there is a clear lack of experimental data that allow one to reveal molecular and cellular adaptations of plants and animals from natural populations to adverse effects of environmental factors. The present study was aimed to assess genotoxic effects in earthworms Aporrectodea caliginosa Savigny and Lumbricus rubellus Hoffmeister sampled from the populations that during numerous generations inhabited the territories with a technogeneously enhanced content of natural origin radionuclides and heavy metals in soil. The levels ofthe DNA damage detected with alkaline and neutral versions of Comet-assay in invertebrates from contaminated territories were established not to differ from the spontaneous level found in the animals from the reference population. At the same time the rate of the DNA damage reparation induced in A. caliginosa sampled from the contaminated sites with additional acute γ-irradiation (4 Gy) was found to be considerably higher as compared with earthworms from the reference population. PMID:25962273

  17. Computational analysis of non-isothermal temperature distribution on natural convection in nanofluid filled enclosures

    NASA Astrophysics Data System (ADS)

    Oztop, Hakan F.; Abu-Nada, Eiyad; Varol, Yasin; Al-Salem, Khaled

    2011-04-01

    In this study, the problem of steady state natural convection in an enclosure filled with a nanofluid has been analyzed numerically by using heating and cooling by sinusoidal temperature profiles on one side. The governing partial differential equations, in terms of the dimensionless stream function-vorticity and temperature, are solved numerically using the finite volume method for various inclination angles 0∘≤ϕ≤90∘, different types of nanoparticles (TiO 2 and Al 2O 3) and fractions of nanoparticles 0≤φ≤0.1, whereas the range of the Rayleigh number Ra is 10 3-10 5. It is found that the addition of nanoparticles into water affects the fluid flow and temperature distribution especially for higher Rayleigh numbers. An enhancement in heat transfer rate was registered for the whole range of Rayleigh numbers. However, low Rayleigh numbers show more enhancement compared to high Rayleigh numbers.

  18. West Virginia crayfishes (Decapoda: Cambaridae): observations on distribution, natural history, and conservation

    USGS Publications Warehouse

    Loughman, Zachary J.; Simon, Thomas P.; Welsh, Stuart A.

    2015-01-01

    West Virginia's crayfishes have received moderate attention since publication of Jezerinac et al.'s (1995) monograph of the state fauna. Survey efforts were initiated over the summers of 2006 and 2007 to gather voucher material for the Indiana Biological Survey's Crustacean Collection. These collections have provided new information regarding the distribution, natural history, life history, taxonomy, and conservation status of Cambarus (Cambarus) carinirostris, C. (C.) bartonii cavatus, C. (C.) sciotensis, C. (Hiaticambarus) chasmodactylus, C. (H.) elkensis, C. (H.) longulus, C. (Jugicambarus) dubius, C. (Puncticambarus) robustus, Orconectes (Procericambarus) cristavarius, and O. (P.) rusticus. Orconectes (Faxonius) limosus has apparently been extirpated from West Virginia and should be removed from the state's list of extant crayfishes.

  19. West Virginia crayfishes (Decapoda: Cambaridae): observations on distribution, natural history, and conservation

    USGS Publications Warehouse

    Loughman, Zachary J.; Simon, Thomas P.; Welsh, Stuart A.

    2009-01-01

    West Virginia's crayfishes have received moderate attention since publication of Jezerinac et al.'s (1995) monograph of the state fauna. Survey efforts were initiated over the summers of 2006 and 2007 to gather voucher material for the Indiana Biological Survey's Crustacean Collection. These collections have provided new information regarding the distribution, natural history, life history, taxonomy, and conservation status of Cambarus (Cambarus) carinirostris, C. (C.) bartonii cavatus, C. (C.) sciotensis, C. (Hiaticambarus) chasmodactylus, C. (H.) elkensis, C. (H.) longulus, C. (Jugicambarus) dubius, C. (Puncticambarus) robustus, Orconectes (Procericambarus) cristavarius, and O. (P.) rusticus. Orconectes (Faxonius) limosus has apparently been extirpated from West Virginia and should be removed from the state's list of extant crayfishes.

  20. Mathematical simulation of sediment and radionuclide transport in estuaries

    SciTech Connect

    Onishi, Y.; Trent, D.S.

    1982-11-01

    The finite element model LFESCOT (Flow, Energy, Salinity, Sediment and Contaminant Transport Model) was synthesized under this study to simulate radionuclide transport in estuaries to obtain accurate radionuclide distributions which are affected by these factors: time variance, three-dimensional flow, temperature, salinity, and sediments. Because sediment transport and radionuclide adsorption/desorption depend strongly on sizes or types of sediments, FLESCOT simulates sediment and a sediment-sorbed radionuclide for the total of three sediment-size fractions (or sediment types) of both cohesive and noncohesive sediments. It also calculates changes of estuarine bed conditions, including bed elevation changes due to sediment erosion/deposition, and three-dimensional distributions of three bed sediment sizes and sediment-sorbed radionuclides within the bed. Although the model was synthesized for radionuclide transport, it is general enough to also handle other contaminants such as heavy metals, pesticides, or toxic chemicals. The model was checked for its capability for flow, water surface elevation change, salinity, sediment and radionuclide transport under various simple conditions first, confirming the general validity of the model's computational schemes. These tests also revealed that FLESCOT can use large aspect ratios of computational cells, which are necessary in handling long estuarine study areas. After these simple tests, FLESCOT was applied to the Hudson River estuary between Chelsea and the mouth of the river to examine how well the model can predict radionuclide transport through simulating tidally influenced three-dimensional flow, salinity, sediment and radionuclide movements with their interactions.

  1. Distribution of potentially bioavailable natural organic carbon in aquifer sediments at a chloroethene-contaminated site

    USGS Publications Warehouse

    Thomas, L.K.; Widdowson, M.A.; Chapelle, F.H.; Novak, J.T.; Boncal, J.E.; Lebrón, C. A.

    2012-01-01

    The distribution of natural organic carbon was investigated at a chloroethene-contaminated site where complete reductive dechlorination of tetrachloroethene (PCE) to vinyl chloride and ethene was observed. In this study, operationally defined potentially bioavailable organic carbon (PBOC) was measured in surficial aquifer sediment samples collected at varying depths and locations in the vicinity of a dense nonaqueous phase liquid (DNAPL) source and aqueous phase plume. The relationship between chloroethene concentrations and PBOC levels was examined by comparing differences in extractable organic carbon in aquifer sediments with minimal chloroethene exposure relative to samples collected in the source zone. Using performance-monitoring data, direct correlations with PBOC were also developed with chloroethene concentrations in groundwater. Results show a logarithm-normal distribution for PBOC in aquifer sediments with a mean concentration of 187  mg/kg. PBOC levels in sediments obtained from the underlying confining unit were generally greater when compared to sediments collected in the sandy surficial aquifer. Results demonstrated a statistically significant inverse correlation (p=0.007) between PBOC levels in aquifer sediments and chloroethene concentrations for selected monitoring wells in which chloroethene exposure was the highest. Results from laboratory exposure assays also demonstrated that sediment samples exhibited a reduction in PBOC levels of 35% and 73%, respectively, after a 72-h exposure period to PCE (20,000  μg/L). These results support the notion that PBOC depletion in sediments may be expected in chloroethene-contaminated aquifers, which has potential implications for the long-term sustainability of monitored natural attenuation.

  2. Horizontal and vertical characterization of radionuclides and minerals in river sediments.

    PubMed

    Ramasamy, V; Suresh, G; Meenakshisundaram, V; Ponnusamy, V

    2011-01-01

    The natural radionuclide ((238)U, (232)Th and (40)K) contents and mineral characteristics have been analyzed for the different depth sediment samples of Ponnaiyar River with an aim of evaluating the radiation hazard and its relation to specific minerals. To know the complete radiological characteristics, the radiological indices have been calculated and compared with recommended values. In an FTIR study, the extinction coefficient and crystallinity index is calculated to find the relative distribution of major minerals and the crystallinity of quartz, respectively. Both horizontal and vertical distributions of radionuclides and major minerals are studied. Multivariate statistical analyses (cluster and factor) were carried out to determine the relationship between the radioactivity and the minerals. Statistical analyses suggest that the kaolinite is the major mineral to increase the level of radioactivity in the river sediments. PMID:20801666

  3. Radionuclides in Diagnosis.

    ERIC Educational Resources Information Center

    Williams, E. D.

    1989-01-01

    Discussed is a radionuclide imaging technique, including the gamma camera, image analysis computer, radiopharmaceuticals, and positron emission tomography. Several pictures showing the use of this technique are presented. (YP)

  4. Immunohistochemical detection and distribution of prion protein in a goat with natural scrapie.

    PubMed

    Valdez, Reginald A; Rock, Matthew J; Anderson, Anne K; O'Rourke, Katherine I

    2003-03-01

    Formalin-fixed, paraffin-embedded tissue sections from a 3-year-old female Angora goat suffering from clinical scrapie were immunostained after hydrated autoclaving using a monoclonal antibody (mAb, F99/97.6.1; IgG1) specific for a conserved epitope on the prion protein. Widespread and prominent deposition of the scrapie isoform of the prion protein (PrPSc) was observed in the brain, brainstem, spinal cord, retina, postganglionic neurons associated with parasympathetic ganglia of myenteric and submucosal plexuses, Peyer's patches, peripheral lymph nodes, and pharyngeal and palatine tonsils. The goat was homozygous for PrP alleles encoding 5 octapeptide repeat sequences in the N-terminal region of the prion protein and isoleucine at codon 142, a genotype associated with high susceptibility and short incubation times in goats. The results of this study indicate that mAb F99/97.6.1 is useful for detection of PrPSc deposition, and this is a specific and reliable immunohistochemical adjunct to histopathology for diagnosis of natural caprine scrapie, although precise determination of the diagnostic sensitivity and specificity of the assay as a diagnostic test for scrapie in goats will require examination of a sufficiently large sample size. As with ovine scrapie, prion protein is widely distributed in the central and peripheral nervous systems, gastrointestinal tract, and lymphoid tissues in natural caprine scrapie. PMID:12661726

  5. Stochastic nature and red cell population distribution of the sickling-induced Ca2+ permeability.

    PubMed Central

    Lew, V L; Ortiz, O E; Bookchin, R M

    1997-01-01

    To explore basic properties of the sickling-induced cation permeability pathway, the Ca2+ component (Psickle-Ca) was studied in density-fractionated sickle cell anemia (SS) discocytes through its effects on the activity of the cells' Ca2+sensitive K+-channels (KCa). The instant state of KCa channel activation was monitored during continuous or cyclic deoxygenation of the cells using a novel thiocyanate-densecell formation method. Each deoxy pulse caused a reversible, sustained Psickle-Ca, which activated KCa channels in only 10-45% of cells at physiological [Ca2+]o ("activated cells"). After removal of cells activated by each previous deoxy pulse, subsequent pulses generated similar activated cell fractions, indicating a random determination rather than the response of a specific vulnerable subpopulation. The fraction of activated cells rose monotonically with [Ca2+]o along a curve reflecting the cells' distribution of Psickle-Ca, with values high enough in a small cell fraction to trigger near-maximal KCa channels. Consistent with the stochastic nature of Psickle-Ca, repeated deoxygenated-oxygenated pulsing led to progressive dense cell formation, whereas single long pulses caused one early density shift. Thus deoxygenation-induced Ca2+-permeabilization in SS cells is a probabilistic event with large cumulative dehydrating potential. The possible molecular nature of Psickle-Ca is discussed. PMID:9169503

  6. The Case for Natural Gas Fueled Solid Oxide Fuel Cell Power Systems for Distributed Generation

    SciTech Connect

    Chick, Lawrence A.; Weimar, Mark R.; Whyatt, Greg A.; Powell, Michael R.

    2015-02-01

    Natural-gas-fueled solid oxide fuel cell (NGSOFC) power systems yield electrical conversion efficiencies exceeding 60% and may become a viable alternative for distributed generation (DG) if stack life and manufacturing economies of scale can be realized. Currently, stacks last approximately 2 years and few systems are produced each year because of the relatively high cost of electricity from the systems. If mass manufacturing (10,000 units per year) and a stack life of 15 years can be reached, the cost of electricity from an NGSOFC system is estimated to be about 7.7 ¢/kWh, well within the price of commercial and residential retail prices at the national level (9.9-10¢/kWh and 11-12 ¢/kWh, respectively). With an additional 5 ¢/kWh in estimated additional benefits from DG, NGSOFC could be well positioned to replace the forecasted 59-77 gigawatts of capacity loss resulting from coal plant closures due to stricter emissions regulations and low natural gas prices.

  7. Mobile Methane Measurements of Natural Gas Distribution and End-use Emissions in Indianapolis

    NASA Astrophysics Data System (ADS)

    Lamb, B. K.; Roscioli, J. R.; Floerchinger, C. R.; Herndon, S. C.; Ferrara, T.

    2015-12-01

    Indianapolis is the site of the INFLUX program to investigate greenhouse gas emissions from a large metropolitan area. A key question in INFLUX is the relative contributions of methane emissions from the local gas distribution system in comparison to biogenic sources, such as the wastewater treatment system and landfills, and of end use emissions from furnaces and other combustion devices downstream of customer gas meters. During February and March, 2015, the Aerodyne van was used to measure methane, ethane, CO2 and other trace gases during mobile sampling traverses through a number of urban and suburban Indianapolis neighborhoods. Signatures of distinct natural gas emissions, biogenic emissions, and combustion emissions were observed in small plumes. In a number of cases, these sources were identified as manhole covers in city streets, where nearby leaks can seep into the local wastewater system. Quantification of ethane and methane from 45 manholes reveal that some had emissions that were clearly biogenic while others had a distinct natural gas signature. This paper describes the results from the analysis of these mobile data in the context of the current Indianapolis methane emission inventory.

  8. Distribution of light in the human retina under natural viewing conditions

    NASA Astrophysics Data System (ADS)

    Gibert, Jorge C.

    Age-related macular degeneration (AMD) is the leading cause of blindness inAmerica. The fact that AMD wreaks most of the damage in the center of the retina raises the question of whether light, integrated over long periods, is more concentrated in the macula. A method, based on eye-tracking, was developed to measure the distribution of light in the retina under natural viewing conditions. The hypothesis was that integrated over time, retinal illumination peaked in the macula. Additionally a possible relationship between age and retinal illumination was investigated. The eye tracker superimposed the subject's gaze position on a video recorded by a scene camera. Five informed subjects were employed in feasibility tests, and 58 naive subjects participated in 5 phases. In phase 1 the subjects viewed a gray-scale image. In phase 2, they observed a sequence of photographic images. In phase 3 they viewed a video. In phase 4, they worked on a computer; in phase 5, the subjects walked around freely. The informed subjects were instructed to gaze at bright objects in the field of view and then at dark objects. Naive subjects were allowed to gaze freely for all phases. Using the subject's gaze coordinates, and the video provided by the scene camera, the cumulative light distribution on the retina was calculated for ˜15° around the fovea. As expected for control subjects, cumulative retinal light distributions peaked and dipped in the fovea when they gazed at bright or dark objects respectively. The light distribution maps obtained from the naive subjects presented a tendency to peak in the macula for phases 1, 2, and 3, a consistent tendency in phase 4 and a variable tendency in phase 5. The feasibility of using an eye-tracker system to measure the distribution of light in the retina was demonstrated, thus helping to understand the role played by light exposure in the etiology of AMD. Results showed that a tendency for light to peak in the macula is a characteristic of some

  9. Ecological distribution and population physiology defined by proteomics in a natural microbial community

    USGS Publications Warehouse

    Mueller, Ryan S.; Denef, Vincent J.; Kalnejais, Linda H.; Suttle, K. Blake; Thomas, Brian C.; Wilmes, Paul; Smith, Richard L.; Nordstrom, D Kirk; McCleskey, R. Blaine; Shah, Menesh B.; VerBekmoes, Nathan C.; Hettich, Robert L.; Banfield, Jillian F.

    2010-01-01

    An important challenge in microbial ecology is developing methods that simultaneously examine the physiology of organisms at the molecular level and their ecosystem level interactions in complex natural systems. We integrated extensive proteomic, geochemical, and biological information from 28 microbial communities collected from an acid mine drainage environment and representing a range of biofilm development stages and geochemical conditions to evaluate how the physiologies of the dominant and less abundant organisms change along environmental gradients. The initial colonist dominates across all environments, but its proteome changes between two stable states as communities diversify, implying that interspecies interactions affect this organism's metabolism. Its overall physiology is robust to abiotic environmental factors, but strong correlations exist between these factors and certain subsets of proteins, possibly accounting for its wide environmental distribution. Lower abundance populations are patchier in their distribution, and proteomic data indicate that their environmental niches may be constrained by specific sets of abiotic environmental factors. This research establishes an effective strategy to investigate ecological relationships between microbial physiology and the environment for whole communities in situ.

  10. Boundary-layer receptivity due to distributed surface imperfections of a deterministic or random nature

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan

    1992-01-01

    Acoustic receptivity of a Blasius boundary layer in the presence of distributed surface irregularities is investigated analytically. It is shown that, out of the entire spatial spectrum of the surface irregularities, only a small band of Fourier components can lead to an efficient conversion of the acoustic input at any given frequency to an unstable eigenmode of the boundary layer flow. The location, and width, of this most receptive band of wavenumbers corresponds to a relative detuning of O(R sub l.b.(exp -3/8)) with respect to the lower-neutral instability wavenumber at the frequency under consideration, R sub l.b. being the Reynolds number based on a typical boundary-layer thickness at the lower branch of the neutral stability curve. Surface imperfections in the form of discrete mode waviness in this range of wavenumbers lead to initial instability amplitudes which are O(R sub l.b.(exp 3/8)) larger than those caused by a single, isolated roughness element. In contrast, irregularities with a continuous spatial spectrum produce much smaller instability amplitudes, even compared to the isolated case, since the increase due to the resonant nature of the response is more than that compensated for by the asymptotically small band-width of the receptivity process. Analytical expressions for the maximum possible instability amplitudes, as well as their expectation for an ensemble of statistically irregular surfaces with random phase distributions, are also presented.

  11. Tectonic and hydrologic control of the nature and distribution of geothermal resources

    SciTech Connect

    Muffler, L.J.P. )

    1993-11-01

    A broad overview of the geologic controls of the nature and distribution of geothermal resources is presented. Under forseeable economics and technology, extraction of geothermal resources is limited to the upper few kilometres of the earth's crust. At these depths, the global distribution of geothermal resources is primarily controlled by plate-tectonic features. Geothermal resources related to igneous intrusions in the upper crust occur along spreading ridges, subduction zones, inter-arc basins, and melting anomalies. Geothermal resources unrelated to igneous intrusions in the upper crust occur most commonly in porous sedimentary rocks near convergent or divergent plate boundaries where regional heat flow is high. Geothermal reservoirs at pressures well in excess of hydrostatic occur commonly in young tectonic basins characterized by high rates of sedimentation and subsidence; these reservoirs are commonly termed [open quotes]geopressured.[close quotes] The hydrologic properties of crustal rocks are very important in determining location, size, and type of geothermal resource. Hot dry rock can result from solidification of a young intrusive body or from conductive heating of impermeable rock around such a body. Convective hydrothermal systems result either from convection of meteoric water around young intrusive bodies or from deep circulation of meteoric water along fracture zones. Geopressured reservoirs are formed in deep sedimentary basins when escape of connate water and water produced by the thermal dehydration of clays is impeded by sediments of low permeability.

  12. [Spatial distribution of human activities and their influences on landscape patterns in Daqingshan Nature Reserve].

    PubMed

    Sun, Ya-Hui; Meng, Li; Tian, Lü; Li, Guo-Liang; Li, Yue-Hui; Sun, Jian-Xin

    2014-11-01

    Based on forest inventory data and field survey information, and by using GIS spatial analysis technique and landscape indices, this paper studied the spatial distribution of three categories of human activities (settlement, roads, and other sources of disturbances) and their impacts on landscape patterns in three sub-divided regions, i. e., the west, central and east regions of the Daqingshan Nature Reserve in Inner Mongolia. Results showed that the impacts of human activities were stronger in the east and west regions and weaker in the central region. Among the three subdivided regions, the landscape pattern in the west region was predominantly affected by other sources of disturbances, making the landscape patterns of coniferous forests, broadleaf forests and shrubs tended to be of aggregated distribution; the central region was mainly affected by roads, resulting in reduced landscape patch aggregation of broadleaf forests and shrubs; the east region was mostly affected by settlement, resulting in increased fragmentation of coniferous forests and broadleaf forests and apparent increases in landscape patch aggregation of shrubs and grasslands. PMID:25898623

  13. Ecological distribution and population physiology defined by proteomics in a natural microbial community

    PubMed Central

    Mueller, Ryan S; Denef, Vincent J; Kalnejais, Linda H; Suttle, K Blake; Thomas, Brian C; Wilmes, Paul; Smith, Richard L; Nordstrom, D Kirk; McCleskey, R Blaine; Shah, Manesh B; VerBerkmoes, Nathan C; Hettich, Robert L; Banfield, Jillian F

    2010-01-01

    An important challenge in microbial ecology is developing methods that simultaneously examine the physiology of organisms at the molecular level and their ecosystem level interactions in complex natural systems. We integrated extensive proteomic, geochemical, and biological information from 28 microbial communities collected from an acid mine drainage environment and representing a range of biofilm development stages and geochemical conditions to evaluate how the physiologies of the dominant and less abundant organisms change along environmental gradients. The initial colonist dominates across all environments, but its proteome changes between two stable states as communities diversify, implying that interspecies interactions affect this organism's metabolism. Its overall physiology is robust to abiotic environmental factors, but strong correlations exist between these factors and certain subsets of proteins, possibly accounting for its wide environmental distribution. Lower abundance populations are patchier in their distribution, and proteomic data indicate that their environmental niches may be constrained by specific sets of abiotic environmental factors. This research establishes an effective strategy to investigate ecological relationships between microbial physiology and the environment for whole communities in situ. PMID:20531404

  14. Ecological distribution and population physiology defined by proteomics in a natural microbial community

    SciTech Connect

    Muller, R; Denef, Vincent; Kalnejals, Linda; Suttle, K Blake; Thomas, Brian; Wilmes, P; Smith, Richard L.; Nordstrom, D Kirk; McCleskey, R Blaine; Shah, Manesh B; Verberkmoes, Nathan C; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2010-01-01

    An important challenge in microbial ecology is developing methods that simultaneously examine the physiology of organisms at the molecular level and their ecosystem level interactions in complex natural systems.We integrated extensive proteomic, geochemical, and biological information from 28 microbial communities collected from an acid mine drainage environment and representing a range of biofilm development stages and geochemical conditions to evaluate how the physiologies of the dominant and less abundant organisms change along environmental gradients. The initial colonist dominates across all environments, but its proteome changes between two stable states as communities diversify, implying that interspecies interactions affect this organism s metabolism. Its overall physiology is robust to abiotic environmental factors, but strong correlations exist between these factors and certain subsets of proteins, possibly accounting for its wide environmental distribution. Lower abundance populations are patchier in their distribution, and proteomic data indicate that their environmental niches may be constrained by specific sets of abiotic environmental factors. This research establishes an effective strategy to investigate ecological relationships between microbial physiology and the environment for whole communities in situ

  15. Method and apparatus for separating radionuclides from non-radionuclides

    DOEpatents

    Harp, Richard J.

    1990-01-01

    In an apparatus for separating radionuclides from non-radionuclides in a mixture of nuclear waste, a vessel is provided wherein the mixture is heated to a temperature greater than the temperature of vaporization for the non-radionuclides but less than the temperature of vaporization for the radionuclides. Consequently the non-radionuclides are vaporized while the non-radionuclides remain the solid or liquid state. The non-radionuclide vapors are withdrawn from the vessel and condensed to produce a flow of condensate. When this flow decreases the heat is reduced to prevent temperature spikes which might otherwise vaporize the radionuclides. The vessel is removed and capped with the radioactive components of the apparatus and multiple batches of the radionuclide residue disposed therein. Thus the vessel ultimately provides a burial vehicle for all of the radioactive components of the process.

  16. Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape

    USGS Publications Warehouse

    Andraski, Brian J.; Jackson, W.A.; Welborn, Toby L.; Böhlke, John Karl; Sevanthi, Ritesh; Stonestrom, David A.

    2014-01-01

    Perchlorate (ClO4−) is a contaminant that occurs naturally throughout the world, but little is known about its distribution and interactions in terrestrial ecosystems. The objectives of this Amargosa Desert, Nevada study were to determine (i) the local-scale distribution of shallow-soil (0–30 cm) ClO4− with respect to shrub proximity (far and near) in three geomorphic settings (shoulder slope, footslope, and valley floor); (ii) the importance of soil, plant, and terrain variables on the hillslope-distribution of shallow-soil and creosote bush [Larrea tridentata (Sessé & Moc. ex DC.) Coville] ClO4−; and (iii) atmospheric (wet plus dry, including dust) deposition of ClO4− in relation to soil and plant reservoirs and cycling. Soil ClO4− ranged from 0.3 to 5.0 μg kg−1. Within settings, valley floor ClO4− was 17× less near shrubs due in part to enhanced leaching, whereas shoulder and footslope values were ∼2× greater near shrubs. Hillslope regression models (soil, R2 = 0.42; leaf, R2 = 0.74) identified topographic and soil effects on ClO4− deposition, transport, and cycling. Selective plant uptake, bioaccumulation, and soil enrichment were evidenced by leaf ClO4− concentrations and Cl−/ClO4− molar ratios that were ∼8000× greater and 40× less, respectively, than soil values. Atmospheric deposition ClO4− flux was 343 mg ha−1 yr−1, ∼10× that for published southwestern wet-deposition fluxes. Creosote bush canopy ClO4− (1310 mg ha−1) was identified as a previously unrecognized but important and active reservoir. Nitrate δ18O analyses of atmospheric deposition and soil supported the leaf-cycled–ClO4− input hypothesis. This study provides basic data on ClO4− distribution and cycling that are pertinent to the assessment of environmental impacts in desert ecosystems and broadly transferable to anthropogenically contaminated systems.

  17. Assessment of gamma radiation exposure and distribution of natural radioactivity in beach sands associated with plutonic rocks of Greece

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Argyrios; Koroneos, Antonios; Christofides, Georgios; Stoulos, Stylianos

    2016-04-01

    This study aims to evaluate the activity concentrations of 238U, 226Ra, 232Th, 228Th and 40K along beaches of Greece associated with plutonic rocks. They range from 6-940, 1-2292, 5-10143, 5-9953 and 27-1319 Bq/kg respectively, with some of them representing the highest values of natural radioactivity measured in sediments in Greece. The investigated beaches include Sithonia peninsula (Chalkidiki, N. Greece), some islands of the Aegean Sea (Mykonos, Paros, Naxos, Serifos, Ikaria), the area of Kavala (N. Greece), Samothraki island, NE Chalkidiki and Maronia (NE Greece). Several of these places are associated with high touristic activity such as Mykonos, Naxos, Paros, Serifos, Ikaria, Sithonia and Kavala. The (% wt.) heavy magnetic fraction (HM) (allanite, amphibole, mica, clinopyroxene, magnetite and hematite), the heavy non-magnetic fraction (HNM) (monazite, zircon, titanite and apatite) and the total heavy fraction (TH), were correlated with the concentrations of the measured radionuclides in the bulk samples. The heavy fractions seem to control the activity concentrations of 238U and 232Th of all the samples, showing some local differences in the main 238U and 232Th mineral carrier. The measured radionuclides in the beach sands were normalized to the respective values measured in the granitic rocks, which are their most probable parental rocks, so as to provide data upon their enrichment or depletion. The highest values of the equivalent dose have been reported in Mykonos, Naxos, Kavala and Sithonia. The annual equivalent dose which should be limited to at least 1 mSv y-1, varies between 0.003 and 0.759 mSv y-1 for tourists and from 0.012 to 3.164 mSv y-1 for local people working on the beach.

  18. COLLABORATION: INTERFACIAL SOIL CHEMISTRY OF RADIONUCLIDES IN THE UNSATURATED ZONE

    EPA Science Inventory

    Mobility of radionuclides (Cs+, Sr2+) in the vadose zone is controlled by sorptive interactions with natural soil particles. Weathering of silicates and intercalation of clay minerals with hydroxy -aluminum and -aluminosilicate species under the intense geochemical conditions in...

  19. Radionuclide characterization and associated dose from long-lived radionuclides in close-in fallout delivered to the marine environment at Bikini and Enewetak Atoll

    SciTech Connect

    Noshkin, V. E.; Robison, W. L.

    1998-09-01

    Between June 1946 and October 1958, Enewetak and Bikini Atolls were used by the United States as testing grounds for 66 nuclear devices. The combined explosive yield from these tests was 107 Mt (Mt TNT equivalents). This testing produced close-in fallout debris that was contaminated with quantities of radioactive fission and particle activated products, and unspent radioactive nuclear fuel that entered the aquatic environment of the atolls. Today, the sediments in the lagoons are reservoirs for 10's of TBq of the transuranics and some long-lived fission and activation products. The larger amounts of contamination are associated with fine and coarse sediment material adjacent to the locations of the high yield explosions. Radionuclides are also distributed vertically in the sediment column to various depths in all regions of the lagoons. Concentrations greater than fallout background levels are found in filtered water sampled over several decades from all locations and depths in the lagoons. This is a direct indication that the radionuclides are continuously mobilized to solution from the solid phases. Of particular importance is the fact that the long-lived radionuclides are accumulated to different levels by indigenous aquatic plants and organisms that are used as food by resident people. One might anticipate finding continuous high contamination levels in many of the edible marine organisms from the lagoons, since the radionuclides associated with the sediments are not contained and are available to the different organisms in a relatively shallow water environment. This is not the case. We estimate that the radiological dose from consumption of the edible parts of marine foods at Enewetak and Bikini is presently about 0.05% of the total 50-year integral effective dose from all other exposure pathways that include ingestion of terrestrial foods and drinking water, external exposure and inhalation. The total radiological dose from the marine pathway is dominated by

  20. The Spatio-Temporal Distribution of Particulate Matter during Natural Dust Episodes at an Urban Scale.

    PubMed

    Krasnov, Helena; Kloog, Itai; Friger, Michael; Katra, Itzhak

    2016-01-01

    Dust storms are a common phenomenon in arid and semi-arid areas, and their impacts on both physical and human environments are of great interest. Number of studies have associated atmospheric PM pollution in urban environments with origin in natural soil/dust, but less evaluated the dust spatial patterns over a city. We aimed to analyze the spatial-temporal behavior of PM concentrations over the city of Beer Sheva, in southern Israel, where dust storms are quite frequent. PM data were recorded during the peak of each dust episode simultaneously in 23 predetermined fixed points around the city. Data were analyzed for both dust days and non-dust days (background). The database was constructed using Geographic Information System and includes distributions of PM that were derived using inverse distance weighted (IDW) interpolation. The results show that the daily averages of atmospheric PM10 concentrations during the background period are within a narrow range of 31 to 48 μg m-3 with low variations. During dust days however, the temporal variations are significant and can range from an hourly PM10 concentration of 100 μg m-3 to more than 1280 μg m-3 during strong storms. IDW analysis demonstrates that during the peak time of the storm the spatial variations in PM between locations in the city can reach 400 μg m-3. An analysis of site and storm contribution to total PM concentration revealed that higher concentrations are found in parts of the city that are proximal to dust sources. The results improve the understanding of the dynamics of natural PM and the dependence on wind direction. This may have implications for environmental and health outcomes. PMID:27513479

  1. Natural Distribution of Parasitoids of Larvae of the Fall Armyworm, Spodoptera frugiperda, in Argentina

    PubMed Central

    Gabriela Murúa, M.; Molina-Ochoa, Jaime; Fidalgo, Patricio

    2009-01-01

    To develop a better understanding of the natural distribution of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), and to update the knowledge of the incidence of its complex of parasitoids. S. frugiperda, samplings in whorl-stage corn were carried out in provinces of Argentina from 1999 to 2003. S. frugiperda larvae were collected from corn in localities of the provinces of Tucumán, Salta, Jujuy, Santiago del Estero, La Rioja, Córdoba, San Luis, Chaco and Misiones. In each locality 30 corn plants were sampled and only larvae located in those plants were collected. The parasitoids that emerged from S. frugiperda larvae were identified and counted. The abundance of the parasitoids and the parasitism rate were estimated. The S. frugiperda parasitoids collected were Campoletis grioti (Blanchard) (Hymenoptera: Ichneumonidae), Chelonus insularis (Cresson) (Hymenoptera: Braconidae), Archytas marmoratus (Townsend) (Diptera Tachinidae) and/or A. incertus (Macquart), Ophion sp. (Hymenoptera: Ichneumonidae), Euplectrus platyhypenae Howard (Hymenoptera: Eulophidae), and Incamyia chilensis (Aldrich) (Diptera Tachinidae). C. grioti was the most abundant and frequent during the five-year survey. Similar diversity of parasitoids was obtained in all the provinces, with the exception of I. chilensis and E. platyhypenae that were recovered only in the province of Salta. In the Northwestern region, in Tucumán, C. grioti and species of Archytas were the most abundant and frequent parasitoids. On the contrary, in Salta and Jujuy Ch. insularis was the parasitoid most abundant and frequently recovered. The parasitism rate obtained in Tucumán, Salta and Jujuy provinces were 21.96%, 17.87% and 6.63% respectively with an average of 18.93%. These results demonstrate that hymenopteran and dipteran parasitoids of S. frugiperda occurred differentially throughout the Argentinian provinces and played an important role on the natural control of the S. frugiperda larval

  2. The Spatio-Temporal Distribution of Particulate Matter during Natural Dust Episodes at an Urban Scale

    PubMed Central

    Krasnov, Helena; Kloog, Itai; Friger, Michael; Katra, Itzhak

    2016-01-01

    Dust storms are a common phenomenon in arid and semi-arid areas, and their impacts on both physical and human environments are of great interest. Number of studies have associated atmospheric PM pollution in urban environments with origin in natural soil/dust, but less evaluated the dust spatial patterns over a city. We aimed to analyze the spatial-temporal behavior of PM concentrations over the city of Beer Sheva, in southern Israel, where dust storms are quite frequent. PM data were recorded during the peak of each dust episode simultaneously in 23 predetermined fixed points around the city. Data were analyzed for both dust days and non-dust days (background). The database was constructed using Geographic Information System and includes distributions of PM that were derived using inverse distance weighted (IDW) interpolation. The results show that the daily averages of atmospheric PM10 concentrations during the background period are within a narrow range of 31 to 48 μg m-3 with low variations. During dust days however, the temporal variations are significant and can range from an hourly PM10 concentration of 100 μg m-3 to more than 1280 μg m-3 during strong storms. IDW analysis demonstrates that during the peak time of the storm the spatial variations in PM between locations in the city can reach 400 μg m-3. An analysis of site and storm contribution to total PM concentration revealed that higher concentrations are found in parts of the city that are proximal to dust sources. The results improve the understanding of the dynamics of natural PM and the dependence on wind direction. This may have implications for environmental and health outcomes. PMID:27513479

  3. Distribution and activity of anaerobic ammonium-oxidising bacteria in natural freshwater wetland soils.

    PubMed

    Shen, Li-dong; Wu, Hong-sheng; Gao, Zhi-qiu; Cheng, Hai-xiang; Li, Ji; Liu, Xu; Ren, Qian-qi

    2016-04-01

    Anaerobic ammonium oxidation (anammox) process plays a significant role in the marine nitrogen cycle. However, the quantitative importance of this process in nitrogen removal in wetland systems, particularly in natural freshwater wetlands, is still not determined. In the present study, we provided the evidence of the distribution and activity of anammox bacteria in a natural freshwater wetland, located in southeastern China, by using (15)N stable isotope measurements, quantitative PCR assays and 16S rRNA gene clone library analysis. The potential anammox rates measured in this wetland system ranged between 2.5 and 25.5 nmol N2 g(-1) soil day(-1), and up to 20% soil dinitrogen gas production could be attributed to the anammox process. Phylogenetic analysis of 16S rRNA genes showed that anammox bacteria related to Candidatus Brocadia, Candidatus Kuenenia, Candidatus Anammoxoglobus and two novel anammox clusters coexisted in the collected soil cores, with Candidatus Brocadia and Candidatus Kuenenia being the dominant anammox genera. Quantitative PCR of hydrazine synthase genes showed that the abundance of anammox bacteria varied from 2.3 × 10(5) to 2.2 × 10(6) copies g(-1) soil in the examined soil cores. Correlation analyses suggested that the soil ammonium concentration had significant influence on the activity of anammox bacteria. On the basis of (15)N tracing technology, it is estimated that a total loss of 31.1 g N m(-2) per year could be linked the anammox process in the examined wetland. PMID:26621804

  4. Distribution of Peripheral PrPSc in Sheep with Naturally Acquired Scrapie

    PubMed Central

    Garza, María Carmen; Monzón, Marta; Marín, Belén; Badiola, Juan José; Monleón, Eva

    2014-01-01

    Accumulation of prion protein (PrPSc) in the central nervous system is the hallmark of transmissible spongiform encephalopathies. However, in some of these diseases such as scrapie or chronic wasting disease, the PrPSc can also accumulate in other tissues, particularly in the lymphoreticular system. In recent years, PrPSc in organs other than nervous and lymphoid have been described, suggesting that distribution of this protein in affected individuals may be much larger than previously thought. In the present study, 11 non-nervous/non-lymphoid organs from 16 naturally scrapie infected sheep in advanced stages of the disease were examined for the presence of PrPSc. Fourteen infected sheep were of the ARQ/ARQ PRNP genotype and 2 of the VRQ/VRQ, where the letters A, R, Q, and V represent the codes for amino-acids alanine, arginine, glutamine and valine, respectively. Adrenal gland, pancreas, heart, skin, urinary bladder and mammary gland were positive for PrPSc by immunohistochemistry and IDEXX HerdChek scrapie/BSE Antigen EIA Test in at least one animal. Lung, liver, kidney and skeletal muscle exhibited PrPSc deposits by immunohistochemistry only. To our knowledge, this is the first report regarding the presence of PrPSc in the heart, pancreas and urinary bladder in naturally acquired scrapie infections. In some other organs examined, in which PrPSc had been previously detected, PrPSc immunolabeling was observed to be associated with new structures within those organs. The results of the present study illustrate a wide dissemination of PrPSc in both ARQ/ARQ and VRQ/VRQ infected sheep, even when the involvement of the lymphoreticular system is scarce or absent, thus highlighting the role of the peripheral nervous system in the spread of PrPSc. PMID:24828439

  5. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 10: METERING AND PRESSURE REGULATING STATIONS IN NATURAL GAS TRANSMISSIONS AND DISTRIBUTION

    EPA Science Inventory

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  6. Radioimmunotherapy with alpha-particle emitting radionuclides.

    PubMed

    Zalutsky, M R; Pozzi, O R

    2004-12-01

    An important consideration in the development of effective strategies for radioimmunotherapy is the nature of the radiation emitted by the radionuclide. Radionuclides decaying by the emission of alpha-particles offer the possibility of matching the cell specific reactivity of monoclonal antibodies with radiation with a range of only a few cell diameters. Furthermore, alpha-particles have important biological advantages compared with external beam radiation and beta-particles including a higher biological effectiveness, which is nearly independent of oxygen concentration, dose rate and cell cycle position. In this review, the clinical settings most likely to benefit from alpha-particle radioimmunotherapy will be discussed. The current status of preclinical and clinical research with antibodies labeled with 3 promising alpha-particle emitting radionuclides - (213)Bi, (225)Ac, and (211)At - also will be summarized. PMID:15640792

  7. Natural radioactivity distribution and gamma radiation exposure of beach sands from Sithonia Peninsula

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Argyrios; Christofides, Georgios; Koroneos, Antonios; Stoulos, Stylianos

    2014-06-01

    This study aims to evaluate the activity concentrations of 238U, 226Ra, 232Th, 228Th and 40K along the beaches of Sithonia Peninsula which are adjacent to the rock-types of the Sithonia Plutonic Complex. These range from 6-673, 5-767, 5-1750, 6-1760 and 185-875 Bq/kg respectively. The (% wt.) heavy magnetic (HM) fraction (epidote, allanite, hornblende, biotite and garnet), the heavy non-magnetic (HNM) fraction (monazite, zircon, titanite and apatite) and the total heavy (TH) fraction, were correlated with the concentrations of the measured radionuclides in the bulk samples. The HNM fraction seems to control the activity concentrations of 238U in all samples, while the HM fraction, at least for the heavy mineral rich samples bearing high amounts of epidote crystals with allanite cores, controls their 232Th content. The measured radionuclides in beach sands were normalized to the respective values measured in the granitic rocks, which are their most probable parent rocks, in order to provide data on their enrichment or depletion. The annual effective dose varies from 0.013 to 0.688 mSv y-1 for local people working on the beach, while for tourists the annual external effective dose ranges between 0.003 and 0.165 mSv y-1.

  8. Chemical behavior of long-lived radionuclides in the marine environment

    SciTech Connect

    Edgington, D.N.; Nelson, D.M.

    1983-01-01

    Measurements of long-lived radionuclides in the marine environment have provided a wealth of information regarding the physical, biological, and chemical processes which control the behavior of these and many other pollutants in the oceans. Their value as tracers for the dispersion, transport, and fate of pollutants in the oceans is largely dependent on the chemical properties of each individual radioelement. Differences in these properties, particularly in relation to their interaction with biotic or abiotic particulate matter, result in the separation of parent-daughter radioisotopes in the natural radioelement series or in changes in the ratios of fission and activation products. Such differences have provided the means to provide time scales for a variey of transport processes and to determine sedimentation rates. The properties of these radionuclides in the oceans can, in general, be predicted from the chemical properties of the stable elements. For those elements such as plutonium, for which there are no naturally-occurring stable isotopes, studies of their distribution in the oceans have provided a new important understanding of their chemical behavior. This behavior has not always agreed with what would have been predicted from laboratory studies carried out at far higher concentrations. Differences between observed distributions and laboratory predictions have highlighted the importance of correct experimental conditions in order to avoid confusing experimental artifacts. The interaction of radionuclides with particles in the oceans and marine sediments can be described in terms of simple ion exchange or adsorption equilibria.

  9. Idaho radionuclide exposure study: Literature review

    SciTech Connect

    Baker, E.G.; Freeman, H.D.; Hartley, J.N.

    1987-10-01

    Phosphate ores contain elevated levels of natural radioactivity, some of which is released to the environment during processing or use of solid byproducts. The effect of radionuclides from Idaho phosphate processing operations on the local communities has been the subject of much research and study. The literature is reviewed in this report. Two primary radionuclide pathways to the environment have been studied in detail: (1) airborne release of volatile radionuclides, primarily /sup 210/Po, from calciner stacks at the two elemental phosphorus plants; and (2) use of byproduct slag as an aggregate for construction in Soda Springs and Pocatello. Despite the research, there is still no clear understanding of the population dose from radionuclide emissions, effluents, and solid wastes from phosphate processing plants. Two other potential radionuclide pathways to the environment have been identified: radon exhalation from phosphogypsum and ore piles and contamination of surface and ground waters. Recommendations on further study needed to develop a data base for a complete risk assssment are given in the report.

  10. Radionuclide Mobility at the Nevada Test Site

    SciTech Connect

    Hu, Q; Smith, D; Rose, T; Glascoe, L; Steefel, C; Zavarin, M

    2003-11-13

    Underground nuclear tests conducted at the Nevada Test Site (NTS) are characterized by abundant fission product and actinide source terms. Included are {sup 99}Tc and other soluble radionuclides ({sup 3}H, {sup 14}C, {sup 36}Cl, {sup 85}Kr, and {sup 129}I), which are presumably mobile in groundwater and potentially toxic to down-gradient receptors. NTS provides the Office of Civilian Radioactive Waste Management (OCRWM) with an analog of the release of these radionuclides from a nuclear waste repository in the absence of engineered barriers. The investigation described in this report synthesizes a substantial body of data collected on the identity and distribution of soluble radionuclides at field scales over distances of hundreds of meters, for durations up to 40 years, and under hydrogeologic conditions very similar to the proposed geological repository at Yucca Mountain. This body of data is complemented by laboratory transport studies and a synthesis of recent modeling investigations from the NTS, with an emphasis on the ongoing Yucca Mountain Program (YMP) efforts. Overall, understanding the controls of radionuclide mobility associated with these nuclear tests will provide insight into the repository's future performance as well as bounds and calibrations for the numerical predictions of long-term radionuclide releases and migration.

  11. [Spatial distribution of soil total nitrogen in Liangshui National Nature Reserve based on local model].

    PubMed

    Zhen, Zhen; Guo, Zhi-ying; Zhao, Ying-hui; Li, Feng-ri; Wei, Qing-bin

    2016-02-01

    Based on LiDAR data of Liangshui National Nature Reserve, digital elevation model (DEM) was constructed and both primary terrain attributes (slope, aspect, profile curvature, etc.) and secondary terrain attributes (wetness index, sediment transport index, relative stream power index, etc.) were extracted. According to the theory of soil formation, geographically weighted regression (GWR) was applied to predict soil total nitrogen (TN) of the area, and the predicted results were compared with those of three traditional interpolation methods including inverse distance weighting (IDW), ordinary Kriging (OK) and universal Kriging (UK). Results showed that the prediction accuracy of GWR (77.4%) was higher than that of other three interpolation methods and the accuracy of IDW (69.4%) was higher than that of OK (63.5%) and UK (60.6%). The average of TN predicted by GWR reached 4.82 g . kg-1 in the study area and TN tended to be higher in the region with higher elevation, bigger wetness index and stronger relative stream power index than in other areas. Further, TN also varied partly with various aspects and slopes. Thus, local model using terrain attributes as independent variables was effective in predicting soil attribute distribution. PMID:27396130

  12. Planning replacement of natural gas distribution systems under constraints on acceptable risk from explosions.

    PubMed

    Noonan, F

    1991-12-01

    Natural gas distribution systems in the United States were developed primarily in the first half of this century, utilizing materials such as cast iron and then steel. Over time, cast iron and steel pipe sections became weak from corrosion and are subject to failure which in turn can lead to explosions and possible injury and loss of life. Gas utilities maintain system integrity through repair-replacement programs where pipe sections are prioritized for replacement in any given year through cost-benefit analysis; however, the total annual amount to be budgeted for replacement is left to engineering judgment. This approach has left some utilities vulnerable to criticism that their current replacement rate on cast iron pipe is not great enough and that public safety is being compromised. This paper addresses the problem situation by formulating a linear programming replacement decision model which augments cost-benefit analysis with explicit constraints on acceptable risk to human life from fire/explosion. The model is illustrated for a hypothetical utility. PMID:1780504

  13. A mobile tool about causes and distribution of dramatic natural phenomena

    NASA Astrophysics Data System (ADS)

    Boppidi, Ravikanth Reddy

    Most Research suggests that tablet computers could aid the study of many scientific concepts that are difficult to grasp, such as places, time and statistics. These occur especially in the study of geology, chemistry, biology and so on. Tapping the technology will soon become critical career training for future generations. Teaching through mobile is more interactive and helps students to grasp quickly. In this thesis an interactive mobile tool is developed which explains about the causes and distribution of natural disasters like Earthquakes, Tsunami, Tropical Cyclones, Volcanic Eruptions and Tornadoes. The application shows the places of disasters on an interactive map and it also contains YouTube embedded videos, which explain the disasters visually. The advantage of this tool is, it can be deployed onto major mobile operating systems like Android and IOS. The application's user interface (UI) is made very responsive using D3 JavaScript, JQuery, Java Script, HTML, CSS so that it can adapt to mobiles, tablets, and desktop screens.

  14. Natural (13) C distribution in oil palm (Elaeis guineensis Jacq.) and consequences for allocation pattern.

    PubMed

    Lamade, Emmanuelle; Tcherkez, Guillaume; Darlan, Nuzul Hijri; Rodrigues, Rosario Lobato; Fresneau, Chantal; Mauve, Caroline; Lamothe-Sibold, Marlène; Sketriené, Diana; Ghashghaie, Jaleh

    2016-01-01

    Oil palm has now become one of the most important crops, palm oil representing nearly 25% of global plant oil consumption. Many studies have thus addressed oil palm ecophysiology and photosynthesis-based models of carbon allocation have been used. However, there is a lack of experimental data on carbon fixation and redistribution within palm trees, and important C-sinks have not been fully characterized yet. Here, we carried out extensive measurement of natural (13) C-abundance (δ(13) C) in oil palm tissues, including fruits at different maturation stages. We find a (13) C-enrichment in heterotrophic organs compared to mature leaves, with roots being the most (13) C-enriched. The δ(13) C in fruits decreased during maturation, reflecting the accumulation in (13) C-depleted lipids. We further used observed δ(13) C values to compute plausible carbon fluxes using a steady-state model of (13) C-distribution including metabolic isotope effects ((12) v/(13) v). The results suggest that fruits represent a major respiratory loss (≈39% of total tree respiration) and that sink organs such as fruits are fed by sucrose from leaves. That is, glucose appears to be a quantitatively important compound in palm tissues, but computations indicate that it is involved in dynamic starch metabolism rather that C-exchange between organs. PMID:26228944

  15. Variation in KRAS driver substitution distributions between tumor types is determined by both mutation and natural selection

    PubMed Central

    Ostrow, Sheli L.; Simon, Einav; Prinz, Elad; Bick, Tova; Shentzer, Talia; Nagawkar, Sima S.; Sabo, Edmond; Ben-Izhak, Ofer; Hershberg, Ruth; Hershkovitz, Dov

    2016-01-01

    Different tumor types vary greatly in their distribution of driver substitutions. Here, we analyzed how mutation and natural selection contribute to differences in the distribution of KRAS driver substitutions between lung, colon and pancreatic adenocarcinomas. We were able to demonstrate that both differences in mutation and differences in selection drive variation in the distribution of KRAS driver substitutions between tumor types. By accounting for the effects of mutation on the distribution of KRAS driver substitutions, we could identify specific KRAS driver substitutions that are more favored by selection in specific tumor types. Such driver substitutions likely improve fitness most when they occur within the context of the tumor type in which they are preferentially favored. Fitting with this, we found that driver substitutions that are more favored by natural selection in a specific type of tumor tend to associate with worse clinical outcomes specifically in that type of tumor. PMID:26902163

  16. RADIONUCLIDE TRANSPORT IN FRACTURED TUFF UNDER EPISODIC FLOW CONDITIONS

    SciTech Connect

    O. Hu; Y. Sun; R.P. Ewing

    2005-09-19

    The current conceptual model of radionuclide transport in unsaturated fractured rock includes water movement in fractures, with migration of the entrained radionuclides being retarded by diffusion into and sorption within the rock matrix. Water infiltration and radionuclide transport through low-permeability unsaturated fractured rock are episodic and intermittent in nature, at least at local scales. Under episodic flow conditions, the matrix is constantly imbibing or draining, and this fluctuating wetness both drives two-way advective movement of radionuclides, and forces changes in the matrix diffusivity. This work is intended to examine, both experimentally and numerically, how radionuclide transport under episodic flow conditions is affected by the interacting processes of imbibition and drainage, diffusion, and matrix sorption. Using Topopah Spring welded volcanic tuff, collected from the potential repository geologic unit at Yucca Mountain for storing high-level nuclear waste, we prepared a saw-cut fracture core (length 10.2 cm, diameter 4.4 cm, and fracture aperture 100 {micro}m). The dry core was packed into a flow reactor, flushed with CO{sub 2}, then saturated via slow pumping (0.01 mL/min) of synthetic groundwater. The fractured core was then flushed with air at >97% relative humidity (to simulate in situ unsaturated fractured rock conditions at Yucca Mountain), then the episodic transport experiment was conducted. Episodic flow involved 4 cycles of tracer solution flow within the fracture, followed by flushing with high humidity air. Each flow episode contained a different suite of non-sorbing and sorbing tracers, which included {sup 3}H, ReO{sub 4}{sup -} (a chemical analog for {sup 99}TcO{sub 4}{sup -}), I{sup -} (for {sup 129}I{sup -}), Sr and Cs (for {sup 90}Sr and {sup 137}Cs), plus the radionuclides {sup 235}U, {sup 237}Np, and {sup 241}Pu. These radionuclides span a variety of sorption strengths and represent a large fraction of the radionuclides

  17. [Plea for a spatialization of demographic growth. Geographic distribution of the population and management of natural resources in the Sahel].

    PubMed

    Ouedraogo, D

    1994-05-01

    The Sahel is characterized by low productivity and unequal distribution of the population and of natural resources. Demographic growth is accompanied by a spatial unequal redistribution of the population, essentially caused by migratory movements. Geographic distribution of the population still follows that of natural resources, especially water which determines agricultural activities. Researchers must remember different spatial levels in the analysis for the interventions most effective on the ground. One fundamental question that is still avoided is: In what Sahelian towns will the 43 million citizens still be living in 2020? Another question is: What pattern of rural supplying of people will there be for the future? Research between natural resource needs of a growing population (3.1%/year) and the need for better management of these resources assumes great importance for sustainable development in the Sahel. Actions aiming to intensify agricultural production and preservation of natural resources are more and more reaffirmed by those tending to reduce the demand in these resources thanks to the control of demographic growth in the Sahel. But the reach of these actions will remain limited so long as they will not be trimmed to different spatial scales. Natural resources are unequally distributed to the Sahel. On the strictly demographic plan, the geographic distribution of the population and its evolution linked to the migratory fluxes constitute some variable keys that one will not know how to continue to escape in the construction of true sustainable development in the Sahel. PMID:12288132

  18. Colloid-Facilitated Radionuclide Transport at the Potential Yucca Mountain Repository

    NASA Astrophysics Data System (ADS)

    Alcorn, S. R.; Mertz, C. J.

    2001-12-01

    In a geologic repository for nuclear waste, transport of radionuclides on or within colloids may be important for radionuclides of concern that have low solubility and can be entrained in, or sorbed onto, colloidal particles generated within the repository system. It is anticipated that colloids will be formed and mobilized at the potential Yucca Mountain repository as a result of alteration of high-level radioactive waste (HLW) and spent nuclear fuel (SNF) waste forms, as well as corrosion of engineered barrier system (EBS) components. The abundance of colloids leaving a breached waste package and entering the repository drift will depend on the extent of waste form and EBS component alteration and the alteration products formed. Further, colloid abundance and stability will depend on such environmental factors as the ionic strength, pH, cation concentrations, natural colloid content, and organic acid and microbe content of groundwater entering the waste package from the drift. Colloids may flocculate and settle, be chemically retarded, mechanically filtered, or dissolve. In addition, colloids may sorb readily at the interfaces between air and water in rocks and engineered barriers and, depending upon the characteristics and degree of saturation of the porous medium, may be immobilized, retarded, or transported. A methodology for modeling colloid-facilitated radionuclide transport in the potential repository at Yucca Mountain was developed for use in Total System Performance Assessment calculations. The model incorporates several colloid sources and addresses factors affecting colloid stability and concentration as well as distribution and attachment of radionuclides onto colloids. Waste form corrosion tests performed at Argonne National Laboratory (ANL) have focused on determination of colloid composition, stability, concentration, size distribution, and associated radionuclide concentration. Data from these experiments were used as model inputs.

  19. Radionuclide transport coupled with bentonite extrusion in a saturated fracture system

    NASA Astrophysics Data System (ADS)

    Borrelli, Robert Angelo

    The study in this dissertation focuses on the characterization of radionuclide migration in a water saturated fracture. The near field of a high level radioactive waste repository contains the engineered barrier system, which provides manufactured components designed to limit radionuclide releases to the environment. A major component in this system involves the utilization of bentonite as a buffer to protect the degraded waste package and limit release of radionuclides into intersecting fractures that pose possible pathways for transport to the environment. A model is derived for radionuclide migration through this fracture. The model incorporates the features of bentonite: extrusion into the fracture, sorption, and the effect of bentonite swelling on groundwater flow. The resulting derivation of this model is a coupled system of differential equations. The differential equation describing the mass conservation of radionuclides is coupled to the equation system for bentonite extrusion. The models are coupled through the parameters in the radionuclide transport model, which are dependent on the spatial distribution of solid material in the domain. Numerical evaluations of the solution to this radionuclide transport model were conducted for neptunium, a weakly sorbing radionuclide and americium, a strongly sorbing radionuclide. Results were presented in terms normalized spatial distribution of radionuclide concentration in the fluid phase and normalized radionuclide release rate in the fluid phase. Major findings of the study conducted for this dissertation are provided. (1) Bentonite extrusion affects fluid phase advection resulting in groundwater flow countercurrent to the direction of extrusion to the direction of radionuclide migration. (2) The sorption distribution coefficient is the most important parameter affecting radionuclide behavior in this system for this model. (3) Simulations of the model for americium, a highly sorbing radionuclide, indicate that

  20. Radionuclide studies in impotence

    SciTech Connect

    Hilson, A.J.; Lewis, C.A. )

    1991-04-01

    Impotence may be of physiological origin with causes including vascular or neurological pathology. Alternatively, it may be of psychogenic origin. Clinicians can distinguish between psychological and organic impotence by observing nocturnal penile tumescence. Non-radionuclide investigations for organic impotence include penile plethysmography or pulse Doppler analysis for arterial supply, cavernosometry for venous drainage, and biothesiometry or evoked potentials for neurological pathology. Radionuclide studies are primarily based on the use of technetium 99m-pertechnetate, 99mTc-red blood cells, or xenon 133 to study the blood flow, with or without pharmacological intervention, commonly papaverine. 26 references.

  1. Variability in background levels of surface soil radionuclides in the vicinity of the US DOE waste isolation pilot plant.

    PubMed

    Kirchner, T B; Webb, J L; Webb, S B; Arimoto, R; Schoep, D A; Stewart, B D

    2002-01-01

    Concentrations of radionuclides were measured in soils from a grid of locations surrounding the US Department of Energy Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico and from a grid on a reference site approximately 20 km southeast of the WIPP site. Each of the two grids has 16 sampling locations (grid nodes) systematically distributed within an area of 16.580 ha. Sampling was conducted prior to the arrival of the first waste shipment at WIPP. Thus, the 137Cs and 23,240Pu in the soil are expected to have been deposited as global fallout, although the Gnome Site, 8.8 km southwest of the WIPP, is also a potential source of 239,240Pu and fission products. The reference grid has significantly higher concentrations of fallout and natural radionuclides than the WIPP grid. Up to 80% of the total variability in radionuclide concentrations across the two grids is attributable to differences between grid nodes. Differences between replicates within a location account for 44-50% of the variability in concentrations of the uranium isotopes, but only 11-17% of the variability in the concentrations of the other radionuclides. Samples having similar abundance of radionuclides were spatially aggregated across the terrain. The activity concentrations of the radionuclides were strongly correlated with the concentrations of Al and Pb, and with the percentages of sand, silt and clay in the soil. Normalizing radionuclide concentrations to the concentration of Al or percent fine particles can help adjust for differences in soil textures among samples and facilitate the detection of gradients or temporal changes in soil concentrations. PMID:12054041

  2. Assessing the impact of hazardous constituents on the mobilization, transport, and fate of radionuclides in RCRA waste disposal units.

    SciTech Connect

    Yu, C.; Orlandini, K. A.; Cheng, J. -J.; Biwer, B. M.

    2001-08-29

    This report discusses the impact that hazardous organic chemical constituents could have on the mobilization, transport, and fate of radionuclides in disposal units regulated by the Resource Conservation and Recovery Act (RCRA). The effect on a radionuclide's distribution coefficient (K{sub d}) is used as an indicator. Many factors can affect K{sub d}, including the chemical form of the radionuclide, pH of the leachate, nature of the organic constituents, porosity of the soil, amount of water in the landfill, infiltration rate of the water, presence of a chelating agent or other chemical species, and age of the landfill. A total of 19 radionuclides were studied. Of these, nine (H-3, C-14, Se-79, Sr-90, Tc-99, I-129, U-238, Np-237, and Am-241) were found to have the potential to reach groundwater and cause contamination; the remaining 10 (Co-60, Ni-63, Sb-125,Cs-137, Sm-151, Eu-152, Eu-154, Th-230, Th-232, and Pu-239) were considered less likely to cause groundwater contamination. It was also found that when organic material is in solution, it tends to lower a radionuclide's K{sub d} (and enhance transport), whereas when it is in a solid phase, it tends to increase the K{sub d}. The study introduces a simple model to estimate effective K{sub d} values on the basis of total organic carbon concentrations in landfill leachate. However, given the fact that the effective K{sub d} values of radionuclides in RCRA disposal units can either increase or decrease as the result of many factors, including the form of the organic matter (solid or in solution), the study concludes that whenever they are available, actual (measured) K{sub d} values rather than modeled values should be used to conduct dose and risk assessments of radionuclides in RCRA disposal units.

  3. Sediment and radionuclide transport in rivers: radionuclide transport modeling for Cattaraugus and Buttermilk Creeks, New York

    SciTech Connect

    Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.; Skaggs, R.L.; Walters, W.H.

    1982-12-01

    SERATRA, a transient, two-dimensional (laterally-averaged) computer model of sediment-contaminant transport in rivers, satisfactorily resolved the distribution of sediment and radionuclide concentrations in the Cattaraugus Creek stream system in New York. By modeling the physical processes of advection, diffusion, erosion, deposition, and bed armoring, SERATRA routed three sediment size fractions, including cohesive soils, to simulate three dynamic flow events. In conjunction with the sediment transport, SERATRA computed radionuclide levels in dissolved, suspended sediment, and bed sediment forms for four radionuclides (/sup 137/Cs, /sup 90/Sr, /sup 239/ /sup 240/Pu, and /sup 3/H). By accounting for time-dependent sediment-radionuclide interaction in the water column and bed, SERATA is a physically explicit model of radionuclide fate and migration. Sediment and radionuclide concentrations calculated by SERATA in the Cattaraugus Creek stream system are in reasonable agreement with measured values. SERATRA is in the field performance phase of an extensive testing program designed to establish the utility of the model as a site assessment tool. The model handles not only radionuclides but other contaminants such as pesticides, heavy metals and other toxic chemicals. Now that the model has been applied to four field sites, including the latest study of the Cattaraugus Creek stream system, it is recommended that a final model be validated through comparison of predicted results with field data from a carefully controlled tracer test at a field site. It is also recommended that a detailed laboratory flume be tested to study cohesive sediment transport, deposition, and erosion characteristics. The lack of current understanding of these characteristics is one of the weakest areas hindering the accurate assessment of the migration of radionuclides sorbed by fine sediments of silt and clay.

  4. Colony size-frequency distribution of pocilloporid juvenile corals along a natural environmental gradient in the Red Sea.

    PubMed

    Lozano-Cortés, Diego F; Berumen, Michael L

    2016-04-30

    Coral colony size-frequency distributions can be used to assess population responses to local environmental conditions and disturbances. In this study, we surveyed juvenile pocilloporids, herbivorous fish densities, and algal cover in the central and southern Saudi Arabian Red Sea. We sampled nine reefs with different disturbance histories along a north-south natural gradient of physicochemical conditions (higher salinity and wider temperature fluctuations in the north, and higher turbidity and productivity in the south). Since coral populations with negatively skewed size-frequency distributions have been associated with unfavorable environmental conditions, we expected to find more negative distributions in the southern Red Sea, where corals are potentially experiencing suboptimal conditions. Although juvenile coral and parrotfish densities differed significantly between the two regions, mean colony size and size-frequency distributions did not. Results suggest that pocilloporid colony size-frequency distribution may not be an accurate indicator of differences in biological or oceanographic conditions in the Red Sea. PMID:26520210

  5. The Non-Gaussian Nature of Bibliometric and Scientometric Distributions: A New Approach to Interpretation.

    ERIC Educational Resources Information Center

    Ivancheva, Ludmila E.

    2001-01-01

    Discusses the concept of the hyperbolic or skew distribution as a universal statistical law in information science and socioeconomic studies. Topics include Zipf's law; Stankov's universal law; non-Gaussian distributions; and why most bibliometric and scientometric laws reveal characters of non-Gaussian distribution. (Author/LRW)

  6. Gallbladder radionuclide scan

    MedlinePlus

    ... please enable JavaScript. Gallbladder radionuclide scan is a test that uses radioactive material to check gallbladder function. It is also used to look for bile duct blockage or leak. How the Test is Performed The health care provider will inject ...

  7. Methyl Eugenol: Its Occurrence, Distribution, and Role in Nature, Especially in Relation to Insect Behavior and Pollination

    PubMed Central

    Tan, Keng Hong; Nishida, Ritsuo

    2012-01-01

    This review discusses the occurrence and distribution (within a plant) of methyl eugenol in different plant species (> 450) from 80 families spanning many plant orders, as well as various roles this chemical plays in nature, especially in the interactions between tephritid fruit flies and plants. PMID:22963669

  8. Sorption of radionuclides at tracer level on mineral colloids

    SciTech Connect

    Hadem, N.; Fourest, B.; Guillaumont, R.

    1995-12-01

    Transport of radionuclides by colloids through the geosphere is an important issue in exercises aimed to assess the safety of an underground radwaste repository sited in a water saturated zone. The first problems to deal with are the characterization of the colloids and their capabilities to sorb, at trace level and even at tracer level, radionuclides. This study investigates the relationships between the sorption of short lived {sup 137}Cs{sup +}, {sup 223}Ra{sup 2+}, {sup 227}Th and {sup 131}I{sup -} and the zeta potential, {zeta}-potential, of well identified colloids, as a function of pH (2 to 11), ionic strength, I (10{sup -3} to 1 M), and colloid concentration (up to 2000 ppm). {xi}-potential is the essential parameter to be considered since it reflects both the stability and the surface charge of the colloid. SiO{sub 2}, TiO{sub 2}, A1{sub 2}O{sub 3} and Th{sub 3}(PO{sub 4}){sub 4} colloids have been chosen as `model colloids`. They are not really found in natural media, but are representative of particles with isoelectric points (i.e.p.) ranging between pH 2 to 9. In some cases the effect of the concentration of the elements has been studied as well, to check saturation effects (Cs and I from 10{sup -11} to 10{sup -2}M). Experimental data show that the distribution of radionuclides between the two phases considered depends mainly on zeta potential, but also on other identified factors.

  9. Cosmogenic radionuclides in stone meteorites

    NASA Technical Reports Server (NTRS)

    Cressy, P. J., Jr.

    1976-01-01

    This document presents the techniques and compilation of results of cosmogenic Al-26 measurements at Goddard Space Flight Center on 91 samples of 76 stone meteorites. Short-lived radionuclides, including Na-22, Sc-46, Mn-54, and Co-60, were measured in 13 of these meteorites. About one-third of these data has not previously been published. The results are discussed briefly in terms of (1) depletion of Al-26 and natural potassium due to weathering, (2) possible exposure of several chondrites to an unusually high cosmic-ray flux, (3) comparison of Al-26, Na-22, Sc-46, and Mn5-54 in chondrites with the spallation Ne-22/Ne-21 ratio as a shielding indicator, and (4) comparison of (Al-26)-(Ne-22)/Ne-21 data for achondrite classes with the chondrite trend.

  10. Analysis of radionuclide migration behavior in loess medium

    SciTech Connect

    Wang Zhiming; Li Shushen; Guo Zede

    1995-12-31

    A five-year cooperative research program has been carried out by China Institute for Radiation Protection and Japan Atomic Energy Research Institute to develop safety assessment methodology for disposal of low level radioactive waste. Migration behavior of radionuclides {sup 3}H and {sup 85}Sr through field tests, simulation tests in the laboratory and determination of distribution coefficients is discussed and analyzed in this paper. The results show that the retardation coefficients, R{sub d}, from field tests are about 0.08--3.3 times those from simulation tests and R{sub d} from batch tests are 1.1--44 times those from field tests for {sup 85}Sr and loess medium. It was observed from field tests that radionuclides moved mainly downward under artificial sprinkling and a part of them moved up besides downward under natural rain condition. In addition, it was discovered that the retardation coefficient, R{sub d}, increases with velocity of unsaturated water flow, u, in the analysis.

  11. Wide distribution of thermal brines along Median Tectonic Lines SW Japan: Their chemical nature and origin

    NASA Astrophysics Data System (ADS)

    Kazahaya, K.; Morikawa, N.; Yasuhara, M.; Tsukamoto, H.; Takahashi, H.; Sato, T.; Takahashi, M.; Ohwada, M.; Inamura, A.; Oyama, Y.

    2009-12-01

    Chemical and isotopic studies on groundwater and dissolved gases collected from wells and self-spouting springs in wide areas of SW Japan have been performed to investigate their nature, origin and chemical processes. We also try to classify the groundwater into 3 types; volcanic, non-volcanic but from deep-seated sources, and fossil seawater, and discuss genesis of deep-seated water comparing the spatial distribution of groundwater data with geological and tectonic settings and seismicity. According to the spatial variation of hydrogen and oxygen isotopic ratios of groundwater, oxygen-shifted water is found in wide area in SW Japan not only close to quaternary volcanoes but along the tectonic lines where low frequency seismic events occur. We found many oxygen-shifted waters along 1000 km length of Median Tectonic Line originally related to the water previously categorized as Arima-type thermal water. Arima-type water has more than two times Cl concentration than the present seawater and amounts of free CO2 gas. The isotopic composition of Arima-type water is very similar to that of magmatic gases from island arcs, suggesting that this water occur from dehydration of the subducting slab. To give the other supporting evidence, the flow rate of Arima-type water in various places has been hydrologically obtained and compared with the water circulation balance in the solid earth. The difference between the source and sink of water budget in the solid earth is estimated as 1.3-11x1014 g/yr (Ito et al., 1984), and we calculated that flow rate of 40-400 kg/sec in SW Japan area (1000 km wide) is missing. As of now, our observational results show 10 kg/sec in a limited area which is a summary of only 6 local places. So far we believe these flow rate values are in good agreement to assess the origin of Arima-type water. Co-occurrence of low-Q seismic events and brine water ascent may give another evidence of origin of low-Q quakes.

  12. The nature and distribution of flowing features in a weakly karstified porous limestone aquifer

    NASA Astrophysics Data System (ADS)

    Maurice, L. D.; Atkinson, T. C.; Barker, J. A.; Williams, A. T.; Gallagher, A. J.

    2012-05-01

    SummaryThe nature and distribution of flowing features in boreholes in an area of approximately 400 km2 in a weakly karstic porous limestone aquifer (the Chalk) was investigated using single borehole dilution tests (SBDTs) and borehole imaging. One-hundred and twenty flowing features identified from SBDTs in 24 boreholes have densities which decrease from ∼0.3 m-1 near the water table to ∼0.07 m-1 at depths of more than 40 m below the water table; the average density is 0.20 m-1. There is some evidence of regional lithological control and borehole imaging of three boreholes indicated that most flowing features are associated with marls, hardgrounds and flints that may be developed at a more local scale. Borehole imaging also demonstrated that many flowing features are solutionally enlarged fractures, suggesting that even in carbonate aquifers where surface karst is developed on only a small scale, groundwater flow is still strongly influenced by dissolution. Fully connected solutional pathways can occur over 100s, sometimes 1000s of metres. However, conduits, tubules and fissures may not always be individually persistent along a flowpath, instead being connected together and also connected to unmodified fractures to create a relatively dense network of voids with variable apertures (<0.1 cm to >15 cm). Groundwater therefore moves along flowpaths made up of voids with varying shape and character. Local solutional development of fractures at significant depths below the surface suggests that mixing corrosion and in situ sources of acidity may contribute to solutional enhancement of fractures. The study demonstrates that single borehole dilution testing is a useful method of obtaining a large dataset of flowing features at catchment-regional scales. The Chalk is a carbonate aquifer with small-scale surface karst development and this study raises the question of whether other carbonate aquifers with small-scale surface karst have similar characteristics, and what

  13. A limiting factor for the progress of radionuclide-based cancer diagnostics and therapy--availability of suitable radionuclides.

    PubMed

    Tolmachev, Vladimir; Carlsson, Jörgen; Lundqvist, Hans

    2004-01-01

    Advances in diagnostics and targeted radionuclide therapy of haematological and neuroendocrine tumours have raised hope for improved radionuclide therapy of other forms of disseminated tumours. New molecular target structures are characterized and this stimulates the efforts to develop new radiolabelled targeting agents. There is also improved understanding of factors of importance for choice of appropriate radionuclides. The choice is determined by physical, chemical, biological, and economic factors, such as a character of emitted radiation, physical half-life, labelling chemistry, chemical stability of the label, intracellular retention time, and fate of radiocatabolites and availability of the radionuclide. There is actually limited availability of suitable radionuclides and this is a limiting factor for further progress in the field and this is the focus in this article. The probably most promising therapeutic radionuclide, 211At, requires regional production and distribution centres with dedicated cyclotrons. Such centres are, with a few exceptions in the world, lacking today. They can be designed to also produce beta- and Augeremitters of therapeutic interest. Furthermore, emerging satellite PET scanners will in the near future demand long-lived positron emitters for diagnostics with macromolecular radiopharmaceuticals, and these can also be produced at such centres. To secure continued development and to meet the foreseen requirements for radionuclide availability from the medical community it is necessary to establish specialized cyclotron centres for radionuclide production. PMID:15244250

  14. EBS Radionuclide Transport Abstraction

    SciTech Connect

    J. Prouty

    2006-07-14

    The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment (TSPA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that might result from corrosion or seismic damage. The flux through drip shield breaches is potentially split by the waste package, with some (or all) of the flux being diverted by the waste package and some passing through waste package breaches that might result from corrosion or seismic damage. Neither the drip shield nor the waste package survives an igneous intrusion, so the flux splitting submodel is not used in the igneous scenario class. The flow model is validated in an independent model validation technical review. The drip shield and waste package flux splitting algorithms are developed and validated using experimental data. The transport model considers advective transport and diffusive transport

  15. Nonuniform steam generator U-tube flow distribution during natural circulation tests in ROSA-IV large scale test facility

    SciTech Connect

    Kukita, Y.; Nakamura, H.; Tasaka, K. ); Chauliac, C. )

    1988-08-01

    Natural circulation experiments were conducted in a large-scale (1/48 scale in volume) full-height simulator of a Westinghouse-type pressurized water reactor. This facility has two steam generators each containing 141 full-size U-tubes of 9 different heights. Transition of the natural circulation mode was observed in the experiments as the primary of side mass inventory was decreased. Three major circulation modes were observed: single-phase liquid natural circulation, two-phase natural circulation, and reflux condensation. For all these circulation modes, and during the transitions between the modes, the mass flow distribution among the steam generator U-tubes was significantly nonuniform. The longer U-tubes indicated reversed flow at higher primary side mass inventories and also tended to empty earlier than the shorter U-tubes when the primary side mass inventory was decreased.

  16. Skin dose from radionuclide contamination on clothing

    SciTech Connect

    Taylor, D.C.; Hussein, E.M.A.; Yuen, P.S.

    1997-06-01

    Skin dose due to radio nuclide contamination on clothing is calculated by Monte Carlo simulation of electron and photon radiation transport. Contamination due to a hot particle on some selected clothing geometries of cotton garment is simulated. The effect of backscattering in the surrounding air is taken into account. For each combination of source-clothing geometry, the dose distribution function in the skin, including the dose at tissue depths of 7 mg cm{sup -2} and 1,000 Mg cm{sup -2}, is calculated by simulating monoenergetic photon and electron sources. Skin dose due to contamination by a radionuclide is then determined by proper weighting of & monoenergetic dose distribution functions. The results are compared with the VARSKIN point-kernel code for some radionuclides, indicating that the latter code tends to under-estimate the dose for gamma and high energy beta sources while it overestimates skin dose for low energy beta sources. 13 refs., 4 figs., 2 tabs.

  17. DISTRIBUTION OF PERCHLORATE IN SAMPLES OF SODIUM NITRATE (CHILE SALTPETER) FERTILIZER DERIVED FROM NATURAL CALICHE

    EPA Science Inventory

    Two lots of sodium nitrate fertilizer derived from Chilean caliche were analyzed to determine the distribution of perchlorate throughout the material. Although our samples represent a limited amount, we found that distribution was essentially homogeneous in any 100-g portion. Whe...

  18. Assessment of radionuclide and metal contamination in a thorium rich area in Norway.

    PubMed

    Popic, Jelena Mrdakovic; Salbu, Brit; Strand, Terje; Skipperud, Lindis

    2011-06-01

    The Fen Central Complex in southern Norway, a geologically well investigated area of magmatic carbonatite rocks, is assumed to be among the world largest natural reservoirs of thorium ((232)Th). These rocks, also rich in iron (Fe), niobium (Nb), uranium ((238)U) and rare earth elements (REE), were mined in several past centuries. Waste locations, giving rise to enhanced levels of both radionuclides and metals, are now situated in the area. Estimation of radionuclide and metal contamination of the environment and radiological risk assessment were done in this study. The average outdoor gamma dose rate measured in Fen, 2.71 μGy h(-1), was significantly higher than the world average dose rate of 0.059 μGy h(-1). The annual exposure dose from terrestrial gamma radiation, related to outdoor occupancy, was in the range 0.18-9.82 mSv. The total activity concentrations of (232)Th and (238)U in soil ranged from 69 to 6581 and from 49 to 130 Bq kg(-1), respectively. Enhanced concentrations were also identified for metals, arsenic (As), lead (Pb), chromium (Cr) and zinc (Zn), in the vicinity of former mining sites. Both radionuclide and heavy metal concentrations suggested leaching, mobilization and distribution from rocks into the soil. Correlation analysis indicated different origins for (232)Th and (238)U, but same or similar for (232)Th and metals As, Cr, Zn, nickel (Ni) and cadmium (Cd). The results from in situ size fractionation of water demonstrated radionuclides predominately present as colloids and low molecular mass (LMM) species, being potentially mobile and available for uptake in aquatic organisms of Norsjø Lake. Transfer factors, calculated for different plant species, showed the highest radionuclide accumulation in mosses and lichens. Uptake in trees was, as expected, lower. Relationship analysis of (232)Th and (238)U concentrations in moss and soil samples showed a significant positive linear correlation. PMID:21556423

  19. Radionuclides and mercury in the salt lakes of the Crimea

    NASA Astrophysics Data System (ADS)

    Mirzoyeva, Natalya; Gulina, Larisa; Gulin, Sergey; Plotitsina, Olga; Stetsuk, Alexandra; Arkhipova, Svetlana; Korkishko, Nina; Eremin, Oleg

    2015-11-01

    90Sr concentrations, resulting from the Chernobyl NPP accident, were determined in the salt lakes of the Crimea (Lakes Kiyatskoe, Kirleutskoe, Kizil-Yar, Bakalskoe and Donuzlav), together with the redistribution between the components of the ecosystems. The content of mercury in the waters of the studied reservoirs was also established. Vertical distributions of natural radionuclide activities (238U, 232Th, 226Ra, 210Pb, 40K) and anthropogenic 137Cs concentrations (as radiotracers) were determined in the bottom sediments of the Koyashskoe salt lake (located in the south-eastern Crimea) to evaluate the longterm dynamics and biogeochemical processes. Radiochemical and chemical analysis was undertaken and radiotracer and statistical methods were applied to the analytical data. The highest concentrations of 90Sr in the water of Lake Kiyatskoe (350.5 and 98.0 Bq/m3) and Lake Kirleutskoe (121.3 Bq/m3) were due to the discharge of the Dnieper water from the North-Crimean Canal. The high content of mercury in Lake Kiyatskoe (363.2 ng/L) and in seawater near Lake Kizil-Yar (364 ng/L) exceeded the maximum permissible concentration (3.5 times the maximum). Natural radionuclides provide the main contribution to the total radioactivity (artificial and natural combined) in the bottom sediments of Lake Koyashskoe. The significant concentration of 210Pb in the upper layer of bottom sediments of the lake indicates an active inflow of its parent radionuclide—gaseous 222Rn from the lower layers of the bottom sediment. The average sedimentation rates in Lake Koyashskoe, determined using 210Pb and 137Cs data, were 0.117 and 0.109 cm per year, respectively.

  20. Osteoid osteoma: radionuclide diagnosis

    SciTech Connect

    Helms, C.A.; Hattner, R.S.; Vogler, J.B. III

    1984-06-01

    The double-density sign, seen on radionuclide bone scans, is described for diagnosing osteoid osteomas and for localizing the nidus. Its use in differentiating the nidus of an osteoid osteoma from osteomyelitis is also described. The utility of computed tomography in localization of the nidus is also illustrated. The double-density sign was helpful in diagnosing seven cases of surgically confirmed osteoid osteoma.

  1. Radionuclide bone imaging

    SciTech Connect

    Bassett, L.W.; Gold, R.H.; Webber, M.M.

    1981-12-01

    Radionuclide bone imaging of the skeleton, now well established as the most important diagnostic procedure in detecting bone metastases, is also a reliable method for the evaluation of the progression or regression of metastatic bone disease. The article concentrates on the technetium-99m agents and the value of these agents in the widespread application of low-dose radioisotope scanning in such bone diseases as metastasis, osteomyelitis, trauma, osteonecrosis, and other abnormal skeletal conditions.

  2. Developments in Bioremediation of Soils and Sediments Pollutedwith Metals and Radionuclides: 2. Field Research on Bioremediation of Metals and Radionuclides

    SciTech Connect

    Hazen, Terry C.; Tabak, Henry H.

    2007-03-15

    Bioremediation of metals and radionuclides has had manyfield tests, demonstrations, and full-scale implementations in recentyears. Field research in this area has occurred for many different metalsand radionuclides using a wide array of strategies. These strategies canbe generally characterized in six major categories: biotransformation,bioaccumulation/bisorption, biodegradation of chelators, volatilization,treatment trains, and natural attenuation. For all field applicationsthere are a number of critical biogeochemical issues that most beaddressed for the successful field application. Monitoring andcharacterization parameters that are enabling to bioremediation of metalsand radionuclides are presented here. For each of the strategies a casestudy is presented to demonstrate a field application that uses thisstrategy.

  3. The Random Nature of Genome Architecture: Predicting Open Reading Frame Distributions

    PubMed Central

    McCoy, Michael W.; Allen, Andrew P.; Gillooly, James F.

    2009-01-01

    Background A better understanding of the size and abundance of open reading frames (ORFS) in whole genomes may shed light on the factors that control genome complexity. Here we examine the statistical distributions of open reading frames (i.e. distribution of start and stop codons) in the fully sequenced genomes of 297 prokaryotes, and 14 eukaryotes. Methodology/Principal Findings By fitting mixture models to data from whole genome sequences we show that the size-frequency distributions for ORFS are strikingly similar across prokaryotic and eukaryotic genomes. Moreover, we show that i) a large fraction (60–80%) of ORF size-frequency distributions can be predicted a priori with a stochastic assembly model based on GC content, and that (ii) size-frequency distributions of the remaining “non-random” ORFs are well-fitted by log-normal or gamma distributions, and similar to the size distributions of annotated proteins. Conclusions/Significance Our findings suggest stochastic processes have played a primary role in the evolution of genome complexity, and that common processes govern the conservation and loss of functional genomics units in both prokaryotes and eukaryotes. PMID:19649247

  4. In situ stress and natural fracture distribution in the Ekofisk Field, North Sea

    SciTech Connect

    Teufel, L W; Farrell, H E

    1990-01-01

    In situ stress and natural fractures have been mapped across the structural dome that forms the Ekofisk field in the Norwegian sector of the North Sea. The reservoir rock is chalk and a natural fracture system forms the primary conductive path for produced hydrocarbons and injected fluids. In situ stress measurements have been made using hydraulic fractures and anelastic strain recovery measurements of oriented core. 36 refs., 21 figs., 2 tabs.

  5. A tale of two retinal domains: near-optimal sampling of achromatic contrasts in natural scenes through asymmetric photoreceptor distribution.

    PubMed

    Baden, Tom; Schubert, Timm; Chang, Le; Wei, Tao; Zaichuk, Mariana; Wissinger, Bernd; Euler, Thomas

    2013-12-01

    For efficient coding, sensory systems need to adapt to the distribution of signals to which they are exposed. In vision, natural scenes above and below the horizon differ in the distribution of chromatic and achromatic features. Consequently, many species differentially sample light in the sky and on the ground using an asymmetric retinal arrangement of short- (S, "blue") and medium- (M, "green") wavelength-sensitive photoreceptor types. Here, we show that in mice this photoreceptor arrangement provides for near-optimal sampling of natural achromatic contrasts. Two-photon population imaging of light-driven calcium signals in the synaptic terminals of cone-photoreceptors expressing a calcium biosensor revealed that S, but not M cones, preferred dark over bright stimuli, in agreement with the predominance of dark contrasts in the sky but not on the ground. Therefore, the different cone types do not only form the basis of "color vision," but in addition represent distinct (achromatic) contrast-selective channels. PMID:24314730

  6. Study of quantification and distribution of explosive mixture in a confined space as a result of natural gas leak

    NASA Astrophysics Data System (ADS)

    Tulach, Aleš; Mynarz, Miroslav; Kozubková, Milada

    2014-03-01

    The contribution deals with quantification of natural gas leak from a domestic low pressure pipe to a confined space in relation to formation of explosive concentration. Within the experiments, amount of leak gas was determined considering the character of pipe damage. Leakage coefficients, natural gas expansion and time before reaching the lower explosive limit of a gas-air mixture were taken. Conducted experiments were then modelled using CFD software and the results were verified. In numerical model, several models of flow were used and afterwards following issues were analysed: leakage velocity, spatial distribution of the mixture in a confined space, formation of concentration at the lower explosive limit etc. This work should contribute to better understanding of propagation and distribution of gaseous fuel mixtures in confined spaces and thereby significantly reduce the risk of fires or explosions or prevent them.

  7. Distribution of polychaete assemblage in relation to natural environmental variation and anthropogenic stress

    NASA Astrophysics Data System (ADS)

    Zan, Xiaoxiao; Zhang, Chongliang; Xu, Binduo; Xue, Ying; Ren, Yiping

    2015-08-01

    Polychaete are diverse species of the soft-bottom community, and are often used as indicators in environment monitoring programs. However, the effects of anthropogenic activities and natural environmental variation on polychaete assemblage are rarely addressed. The goals of this study are to identify the effects of natural environmental variation and anthropogenic stress on polychaete assemblage, and to explore the relationship between the polychaete assemblage structure and anthropogenic stress without considering the natural environmental variation. Based on the data collected from the surveys conducted in the tidal flat of Jiaozhou Bay, the relationship between polychaete assemblage structure and environmental variables was determined using multivariate statistical methods including hierarchical cluster analysis, multidimensional scaling (MDS) and canonical correspondence analysis (CCA). The results showed that the polychaete assemblage was dominated by two species, Amphictene japonica and Heteromastus filiformis, and could be divided into two subgroups characterized by high and low species abundance. CCA illustrated that the natural environmental variables including water temperature and the distance from coast had primary effects on the polychaete assemblage structure; while stress of contaminants, such as As and Hg, had the secondary influences; and stress from the aquacultured species, mainly Ruditapes philippinarum, had a limited effect. Colinearity between the natural environmental variables and anthropogenic stress variables caused a critical divergence in the interpretation of CCA results, which highlighted the risk of a lack of information in environment assessment. Glycinde gurjanovae, Sternaspis scutata and Eulalia bilineata may serve as the `contamination indicators', which need to be confirmed in future studies.

  8. Paleo stress contribution to fault and natural fracture distribution in the Cooper Basin

    NASA Astrophysics Data System (ADS)

    Abul Khair, H.; Cooke, D.; Hand, M.

    2015-10-01

    The contribution of the unconventional reservoirs to the global oil and gas production made it important to address the main factors that control high production from these reservoirs. Hydraulic fracturing that intersect natural fractures results in a high stimulated rock volume and high production. Over a decade of effort to use elastic dislocation and different types of restoration to predict fracture network didn't succeed fully in addressing this factor. We used image log fractures and fault network within an iterative boundary element method (iBEM3D) to predict the paleo-tectonic events and the fracture network in the Cooper Basin. The methodology was able to predict only the major tectonic events that occurred after the deposition of the Cooper Basin sediments and contributed to the formation of the natural fractures. As the methodology does not include fault elastic properties, fracture orientations near the faults showed unrealistic results and should not be considered as indicative for the actual natural fractures. The main trend of the Cooper Basin fractures was attributed to post Triassic inter-seismic relaxation after major tectonic compressional events, which resulted in a normal fault stress regime. However, the current day stress regime is believed to be also a major factor in forming some of the natural fractures. Hunter Bowen orogeny in the Late Triassic contributed less to the existing fractures. Whereas, Cainozoic compressional forces played no role in the formation of the Cooper Basin natural fractures.

  9. FishMORPH - An agent-based model to predict salmonid growth and distribution responses under natural and low flows

    PubMed Central

    Phang, S. C.; Stillman, R. A.; Cucherousset, J.; Britton, J. R.; Roberts, D.; Beaumont, W. R. C.; Gozlan, R. E.

    2016-01-01

    Predicting fish responses to modified flow regimes is becoming central to fisheries management. In this study we present an agent-based model (ABM) to predict the growth and distribution of young-of-the-year (YOY) and one-year-old (1+) Atlantic salmon and brown trout in response to flow change during summer. A field study of a real population during both natural and low flow conditions provided the simulation environment and validation patterns. Virtual fish were realistic both in terms of bioenergetics and feeding. We tested alternative movement rules to replicate observed patterns of body mass, growth rates, stretch distribution and patch occupancy patterns. Notably, there was no calibration of the model. Virtual fish prioritising consumption rates before predator avoidance replicated observed growth and distribution patterns better than a purely maximising consumption rule. Stream conditions of low predation and harsh winters provide ecological justification for the selection of this behaviour during summer months. Overall, the model was able to predict distribution and growth patterns well across both natural and low flow regimes. The model can be used to support management of salmonids by predicting population responses to predicted flow impacts and associated habitat change. PMID:27431787

  10. FishMORPH - An agent-based model to predict salmonid growth and distribution responses under natural and low flows.

    PubMed

    Phang, S C; Stillman, R A; Cucherousset, J; Britton, J R; Roberts, D; Beaumont, W R C; Gozlan, R E

    2016-01-01

    Predicting fish responses to modified flow regimes is becoming central to fisheries management. In this study we present an agent-based model (ABM) to predict the growth and distribution of young-of-the-year (YOY) and one-year-old (1+) Atlantic salmon and brown trout in response to flow change during summer. A field study of a real population during both natural and low flow conditions provided the simulation environment and validation patterns. Virtual fish were realistic both in terms of bioenergetics and feeding. We tested alternative movement rules to replicate observed patterns of body mass, growth rates, stretch distribution and patch occupancy patterns. Notably, there was no calibration of the model. Virtual fish prioritising consumption rates before predator avoidance replicated observed growth and distribution patterns better than a purely maximising consumption rule. Stream conditions of low predation and harsh winters provide ecological justification for the selection of this behaviour during summer months. Overall, the model was able to predict distribution and growth patterns well across both natural and low flow regimes. The model can be used to support management of salmonids by predicting population responses to predicted flow impacts and associated habitat change. PMID:27431787

  11. Monitored Natural Attenuation of Inorganic Contaminants in Ground Water Volume 3 Assessment for Radionuclides IncludingTritium, Radon, Strontium, Technetium, Uranium, Iodine, Radium, Thorium, Cesium, and Plutonium-Americium

    EPA Science Inventory

    The current document represents the third volume of a set of three volumes that address the technical basis and requirements for assessing the potential applicability of MNA as part of a ground-water remedy for plumes with nonradionuclide and/or radionuclide inorganic contamina...

  12. Labeling of monoclonal antibodies with radionuclides

    SciTech Connect

    Bhargava, K.K.; Acharya, S.A. )

    1989-07-01

    Antibodies, specifically monoclonal antibodies, are potentially very useful and powerful carriers of therapeutic agents to target tissues and diagnostic agents. The loading or charging of antibodies with agents, especially radiotracers, is reviewed here. The choice of radioisotope for immunodetection and/or immunotherapy is based on its availability, half-life, nature of the radiation emitted, and the metabolic pathways of the radionuclide in the body. Most important of all are the derivatization techniques available for labeling the antibody with the given radionuclide. Isotopes of iodine and divalent metal ions are the most commonly used radionuclides. Antibodies labeled with iodine at tyrosine residues are metabolized rapidly in vivo. This leads to the incorporation of metabolized radioactive iodine into various tissues, mainly the thyroid gland and stomach, and to the accumulation of high levels of circulating iodine in the blood, which masks tumor uptake considerably. To overcome these limitations, the use of iodohippurate as an iodine-anchoring molecule to the protein should be considered. When divalent or multivalent metal ions are used as the preferred radionuclide, bifunctional chelating reagents such as EDTA or DTPA are first coupled to the protein or antibody. These chelating molecules are attached to the protein by formation of an isopeptide linkage between the carboxylate of the chelating reagent and the amino group of the protein. Several procedures are available to generate the isopeptide linkage. When the anchoring of the chelating agent through isopeptide linkage results in the inactivation of the antibody, periodate oxidation of the carbohydrate moiety of the antibody, followed by reductive coupling of chelator, could be considered as an alternative. There is still a need for better, simpler, and more direct methods for labeling antibodies with radionuclides. 78 references.

  13. Natural Products from Plant-associated Microorganisms: Distribution, Structural Diversity, Bioactivity, and Implications of Their Occurrence⊥

    PubMed Central

    Gunatilaka, A. A. Leslie

    2012-01-01

    A growing body of evidence suggests that plant-associated microorganisms, especially endophytic and rhizosphere bacteria and fungi, represent a huge and largely untapped resource of natural products with chemical structures that have been optimized by evolution for biological and ecological relevance. A diverse array of bioactive small molecule natural products has been encountered in these microorganisms. The structures of over 230 metabolites isolated and characterized from over 70 plant-associated microbial strains during the past four years are presented with information on their hosts, culture conditions, and biological activities. Some significant biological and ecological implications of their occurrence are also reviewed. PMID:16562864

  14. Regulatory reform for natural gas pipelines: The effect on pipeline and distribution company share prices

    NASA Astrophysics Data System (ADS)

    Jurman, Elisabeth Antonie

    1997-08-01

    The natural gas shortages in the 1970s focused considerable attention on the federal government's role in altering energy consumption. For the natural gas industry these shortages eventually led to the passage of the Natural Gas Policy Act (NGPA) in 1978 as part of the National Energy Plan. A series of events in the decade of the 1980s has brought about the restructuring of interstate natural gas pipelines which have been transformed by regulators and the courts from monopolies into competitive entities. This transformation also changed their relationship with their downstream customers, the LDCs, who no longer had to deal with pipelines as the only merchants of gas. Regulatory reform made it possible for LDCs to buy directly from producers using the pipelines only for delivery of their purchases. This study tests for the existence of monopoly rents by analyzing the daily returns of natural gas pipeline and utility industry stock price data from 1982 to 1990, a period of regulatory reform for the natural gas industry. The study's main objective is to investigate the degree of empirical support for claims that regulatory reforms increase profits in the affected industry, as the normative theory of regulation expects, or decrease profits, as advocates of the positive theory of regulation believe. I also test Norton's theory of risk which predicts that systematic risk will increase for firms undergoing deregulation. Based on a sample of twelve natural gas pipelines, and 25 utilities an event study concept was employed to measure the impact of regulatory event announcements on daily natural gas pipeline or utility industry stock price data using a market model regression equation. The results of this study provide some evidence that regulatory reforms did not increase the profits of pipeline firms, confirming the expectations of those who claim that excess profits result from regulation and will disappear, once that protection is removed and the firms are operating in

  15. THE NATURE OF STARBURSTS. III. THE SPATIAL DISTRIBUTION OF STAR FORMATION

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F.; Cannon, John M.; Dolphin, Andrew E.; Holtzman, Jon

    2012-11-01

    We map the spatial distribution of recent star formation over a few Multiplication-Sign 100 Myr timescales in 15 starburst dwarf galaxies using the location of young blue helium burning stars identified from optically resolved stellar populations in archival Hubble Space Telescope observations. By comparing the star formation histories from both the high surface brightness central regions and the diffuse outer regions, we measure the degree to which the star formation has been centrally concentrated during the galaxies' starbursts, using three different metrics for the spatial concentration. We find that the galaxies span a full range in spatial concentration, from highly centralized to broadly distributed star formation. Since most starbursts have historically been identified by relatively short timescale star formation tracers (e.g., H{alpha} emission), there could be a strong bias toward classifying only those galaxies with recent, centralized star formation as starbursts, while missing starbursts that are spatially distributed.

  16. Ways of investigating radionuclide migration processes in the lithosphere and hydrosphere

    SciTech Connect

    Belousova, A.P.; Shmakov, A.I.; Galaktionova, O.V.

    1994-12-01

    In Russia, until recently, it was considered that groundwater was protected from surface radioactive contamination by soil and rocks in the zone aeration. Groundwater was not a subject of radiation control. The accident at the Chernobyl Nuclear Power Plant showed, however, that groundwater is vulnerable to radioactive contamination. In this connection, the vulnerability of groundwater to and the problems of protecting groundwater from radioactive contamination became urgent. The assessment of natural protection of groundwater from radioactive contamination is now considered a top priority. The zone of aeration is generally considered to be the zone separating groundwater from surface contamination. In respect to radioactive contamination, soils that may fix a large quantity of radionuclides serve as a protection zone of a higher order. The mapping of protectibility was done for each radionuclide taking into consideration the specific structure of the flow medium and migration properties of a radionuclide. {sup 90}Sr and {sup 137}Cs have different mechanisms of transport; convective transport is characteristic of the former and diffusive transfer of the latter. This is conditioned by different physico-chemical properties of the radionuclides and principally by their sorption capacities. The coefficient of distribution of {sup 90}Sr is in many times less than the coefficient of distribution of {sup 137}Cs. The environmental protection problem in regions with nuclear power plants and in areas subjected to radioactive contamination may be solved using a monitoring, system including interrelated systems of observation and prediction of the lithosphere and the hydrosphere. The problem of mathematical modeling of migration processes is related to the complexities of modeling the processes of flow, mass transfer, and the accompanying physicochemical processes in zones of full and partial saturation, as well as difficulties in mathematical calculations. 4 refs.

  17. EBS Radionuclide Transport Abstraction

    SciTech Connect

    J.D. Schreiber

    2005-08-25

    The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in ''Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration'' (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment for the license application (TSPA-LA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA-LA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that might result from corrosion or seismic damage. The flux through drip shield breaches is potentially split by the waste package, with some (or all) of the flux being diverted by the waste package and some passing through waste package breaches that might result from corrosion or seismic damage. Neither the drip shield nor the waste package survives an igneous intrusion, so the flux splitting submodel is not used in the igneous scenario class. The flow model is validated in an independent model validation technical review. The drip shield and waste package flux splitting algorithms are developed and validated using experimental data. The transport model considers

  18. Radionuclide Sensors for Water Monitoring

    SciTech Connect

    Grate, Jay W.; Egorov, Oleg B.; DeVol, Timothy A.

    2005-09-01

    Radionuclide contamination in the soil and groundwater at U.S. Department of Energy (DOE) sites is a severe problem that requires monitoring and remediation. Radionuclide measurement techniques are needed to monitor surface waters, groundwater, and process waters. Typically, water samples are collected and transported to an analytical laboratory, where costly radiochemical analyses are performed. To date, there has been very little development of selective radionuclide sensors for alpha- and beta-emitting radionuclides such as 90Sr, 99Tc, and various actinides of interest.

  19. SOA YIELDS AND ORGANIC PRODUCT DISTRIBUTION FROM NATURAL HYDROCARBON/NOX IRRADIATIONS

    EPA Science Inventory

    Secondary organic aerosol (SOA) typically comprises one-quarter to one-third of the ambient aerosol mass in summertime urban atmospheres. In tropospheric environments, the main precursors of SOA come from aromatic and natural hydrocarbons. Recent work by various investigators...

  20. Distribution of arsenic and other minerals in rice plants affected by natural straighthead

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006, an outbreak of naturally-occurring (non-chemically-induced) straighthead occurred in some rice (Oryza sativa L.) yield tests in Stuttgart, Arkansas. This straighthead occurrence provided an opportunity to examine the role of minerals in the disorder. Arsenical herbicides are often used to...

  1. Fair Educational Opportunity and the Distribution of Natural Ability: Toward a Prioritarian Principle of Educational Justice

    ERIC Educational Resources Information Center

    Schouten, Gina

    2012-01-01

    In this article, I develop and defend a prioritarian principle of justice for the distribution of educational resources. I argue that this principle should be conceptualized as directing educators to confer a general benefit, where that benefit need not be mediated by improved academic outcomes. I go on to argue that it should employ a metric of…

  2. Elevated Natural Source Water Ammonia and Nitrification in the Distribution Systems of Four Water Utilities

    EPA Science Inventory

    Nitrification in drinking water distribution systems is a concern of many drinking water systems. Although chloramination as a source of nitrification (i.e., addition of excess ammonia or breakdown of chloramines) has drawn the most attention, many source waters contain signific...

  3. Distribution of aflatoxins in shelling and milling fractions of naturally contaminated rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the distribution of an economically-important class of mycotoxins, the aflatoxins, in rice milling fractions. Rice plants grown under field production condition are frequently infected with types of pathogenic fungi which produce toxic metabolites (mycot...

  4. Mass Spectrometric Radionuclide Analyses

    SciTech Connect

    Wacker, John F.; Eiden, Greg C.; Lehn, Scott A.

    2006-02-01

    Measurement of ionized atoms by mass spectrometry is an alternative to radiation detection for measuring radioactive isotopes. These systems are large and complex; they require trained operators and extensive maintenance. They began as research systems but have been developed commercially for measuring amounts of radioactive isotopes and their atom ratios to other isotopes. Several types of mass spectrometer systems are in use. This chapter covers the basics of mass spectrometry and surveys the application of these instruments for radionuclide detection and discusses the circumstances under which use of mass spectrometers is advantageous, the type of mass spectrometer used for each purpose, and the conditions of sample preparation, introduction and analysis.

  5. Distribution of naturally occurring radioactivity and ¹³⁷Cs in the marine sediment of Farasan Island, southern Red Sea, Saudi Arabia.

    PubMed

    Al-Zahrany, A A; Farouk, M A; Al-Yousef, A A

    2012-11-01

    The present work is a part of a project dedicated to measure the marine radioactivity near the Saudi Arabian coasts of the Red Sea and Arabian Gulf for establishing a marine radioactivity database, which includes necessary information on the background levels of both naturally occurring and man-made radionuclides in the marine environment. Farasan Islands is a group of 84 islands (archipelago), under the administration of the Kingdom of Saudi Arabia, in the Red Sea with its main island of Farasan, which is 50 km off the coast of Jazan City. The levels of natural radioactivity of (238)U, (235)U, (226)Ra, (232)Th and (40)K and man-made radionuclides such as (137)Cs in the grab sediment and water samples around Farasan Island have been measured using gamma-ray spectroscopy. The average activity concentrations of (238)U, (235)U, (226)Ra, (232)Th, (40)K and (137)Cs in the sediment samples were found to be 35.46, 1.75, 3.31, 0.92, 34.34 and 0.14 Bq kg(-1), respectively. PMID:22923246

  6. Distribution of Economic Benefits from Ecotourism: A Case Study of Wolong Nature Reserve for Giant Pandas in China

    NASA Astrophysics Data System (ADS)

    He, Guangming; Chen, Xiaodong; Liu, Wei; Bearer, Scott; Zhou, Shiqiang; Cheng, Lily Yeqing; Zhang, Hemin; Ouyang, Zhiyun; Liu, Jianguo

    2008-12-01

    Ecotourism is widely promoted as a conservation tool and actively practiced in protected areas worldwide. Theoretically, support for conservation from the various types of stakeholder inside and outside protected areas is maximized if stakeholders benefit proportionally to the opportunity costs they bear. The disproportional benefit distribution among stakeholders can erode their support for or lead to the failure of ecotourism and conservation. Using Wolong Nature Reserve for Giant Pandas (China) as an example, we demonstrate two types of uneven distribution of economic benefits among four major groups of stakeholders. First, a significant inequality exists between the local rural residents and the other types of stakeholder. The rural residents are the primary bearers of the cost of conservation, but the majority of economic benefits (investment, employment, and goods) in three key ecotourism sectors (infrastructural construction, hotels/restaurants, and souvenir sales) go to other stakeholders. Second, results show that the distribution of economic benefits is unequal among the rural residents inside the reserve. Most rural households that benefit from ecotourism are located near the main road and potentially have less impact on panda habitat than households far from the road and closer to panda habitats. This distribution gap is likely to discourage conservation support from the latter households, whose activities are the main forces degrading panda habitats. We suggest that the unequal distribution of the benefits from ecotourism can be lessened by enhancing local participation, increasing the use of local goods, and encouraging relocation of rural households closer to ecotourism facilities.

  7. Radionuclides' Content Speciation and Fingerprinting of Nigerian Tin Mining Tailings

    NASA Astrophysics Data System (ADS)

    Olise, F. S.; Oladejo, O. F.; Owoade, O. K.; Almeida, S. M.; Ho, M. D.; Olaniyi, H. B.

    2012-04-01

    Sediment and process-waste samples rich in cassiterite, monazite and zircon, which are of industrial interest, were analysed for the natural series radionuclides, 232Th and 238U and the non-series radionuclide, 40K using instrumental neutron activation analysis (INAA) technique. The natural radionuclides' radioactivity in the samples from the tin-rich areas of Jos, Nigeria was determined using K0-INAA. The obtained results have a high degree of reliability judging from the techniqués accuracy, precision and its non-dependence on secular equilibrium and density correction problems inherent in gamma spectrometry as well as rigorous contamination-prone sample preparation requirements of other methods. Radionuclides speciation and ratios, giving radionuclide fingerprinting of the tin mining tailings is reported. The measured radionuclides activity levels are several orders of magnitude higher than UNSCEAR reference values, revealing the pollution potential of the tin mining and process activities on the surrounding areas, vis-à-vis heavy particulate matter load, leaching into various water channels and direct exposure to gamma rays emitted from the houses and facilities built from the generated wastes. The observed activity levels reflects possible worst scenario situation and the data would not only be of use to the government in its remediation plan for the study area but will also serve as important information for the nuclear science and technology programme about to be embarked upon. Methods of checking exposure have also been suggested.

  8. Grain Size Distribution in Mudstones: A Question of Nature vs. Nurture

    NASA Astrophysics Data System (ADS)

    Schieber, J.

    2011-12-01

    Grain size distribution in mudstones is affected by the composition of the source material, the processes of transport and deposition, and post-depositional diagenetic modification. With regard to source, it does make a difference whether for example a slate belt is eroded vs a stable craton. The former setting tends to provide a broad range of detrital quartz in the sub 62 micron size range in addition to clays and greenschist grade rock fragments, whereas the latter may be biased towards coarser quartz silt (30-60 microns), in addition to clays and mica flakes. In flume experiments, when fine grained materials are transported in turbulent flows at velocities that allow floccules to transfer to bedload, a systematic shift of grain size distribution towards an increasingly finer grained suspended load is observed as velocity is lowered. This implies that the bedload floccules are initially constructed of only the coarsest clay particles at high velocities, and that finer clay particles become incorporated into floccules as velocity is lowered. Implications for the rock record are that clay beds deposited from decelerating flows should show subtle internal grading of coarser clay particles; and that clay beds deposited from continuous fast flows should show a uniform distribution of coarse clays. Still water settled clays should show a well developed lower (coarser) and upper (finer) subdivision. A final complication arises when diagenetic processes, such as the dissolution of biogenic silica, give rise to diagenetic quartz grains in the silt to sand size range. This diagenetic silica precipitates in fossil cavities and pore spaces of uncompacted muds, and on casual inspection can be mistaken for detrital quartz. In distal mudstone successions close to 100 % of "apparent" quartz silt can be of that origin, and reworking by bottom currents can further enhance a detrital perception by producing rippled and laminated silt beds. Although understanding how size

  9. Dynamics and transformations of radionuclides in soils and ecosystem health

    SciTech Connect

    Fellows, Robert J. ); Ainsworth, Calvin C. ); Driver, Crystal J. ); Cataldo, Dominic A. )

    1998-12-01

    The chemical behavior of radionuclides can vary widely in soil and sediment environments. Equally important, for a given radionuclide the physico-chemical properties of the solids and aqueous phase can greatly influence a radionuclides behavior. Radionuclides can conceivably occur in soils as soluble-free, inorganic-soluble-complexed, organic-soluble, complexed, adsorbed, precipitated, coprecipitated, or solid structural species. While it is clear that an assessment of a radionuclide?s soil chemistry and potential shifts in speciation will yield a considerable understanding of its behavior in the natural environment, it does not directly translate to bioavailability or its impact on ecosystems health. The soil chemical factors have to be linked to food chain considerations and other ecological parameters that directly tie to an analysis of ecosystem health. In general, the movement of radionuclides from lower to higher trophic levels diminishes with each trophic level in both aqua tic and terrestrial systems. In some cases, transfer is limited because of low absorption/assimilation by successive trophic organisms (Pu, U); for other radionuclides (Tc, H) assimilation may be high but rapid metabolic turnover and low retention greatly reduce tissue concentrations available to predator species. Still others are chemical analogs of essential elements whose concentrations are maintained under strict metabolic control in tissues (Cs) or are stored in tissues seldom consumed by other organisms (Sr storage in exoskeleton, shells, and bone). Therefore, the organisms that receive the greatest ingestion exposures are those in lower trophic positions or are in higher trophic levels but within simple, short food chains. Food source, behavior, and habitat influence the accumulation of radionuclides in animals.

  10. Data Mining, Ingestion and Distribution of Planetary Data on Natural Satellites

    NASA Astrophysics Data System (ADS)

    Thuillot, W.; Lainey, V.; Meunier, L.-E.; Normand, J.; Arlot, J.-E.; Dehant, V.; Oberst, J.; Rosenblatt, P.; Vermeersen, B.; Dirkx, D.; Gurvits, L.; Marty, J.-C.; Hussmann, H.; FP7-ESPaCE Team

    2015-09-01

    In the framework of the European Union project entitled ESPaCE (European Satellite Partnership for Computing Ephemerides) we have carried out research by collecting unexploited space data and ground-based data for providing new dynamical orbit models and ephemeris of natural satellites and spacecraft orbits. Besides new digitization of old astrometric plate data, Radio Science, VLBI tracking, Laser Ranging methods are applied to these goals. Furthermore shape and gravity field data, reference systems are provided for several natural satellites. This project intends to put all this material online for free access by the scientific community. We describe here the data mining performed, the various data and metadata involved, and the set-up of an astrometric database.

  11. MICROBIAL TRANSFORMATIONS OF RADIONUCLIDES AND ENVIRONMENTAL RESTORATION THROUGH BIOREMEDIATION.

    SciTech Connect

    FRANCIS, A.J.

    2006-09-29

    Treatment of waste streams containing radionuclides, the remediation of contaminated materials, soils, and water, and the safe and economical disposal of radionuclides and toxic metals containing wastes is a major concern. Radionuclides may exist in various oxidation states and may be present as oxide, coprecipitates, inorganic, and organic complexes depending on the process and waste stream. Unlike organic contaminants, the metals cannot be destroyed, but must either be converted to a stable form or removed. Microorganisms present in the natural environment play a major role in the mobilization and immobilization of radionuclides and toxic metals by direct enzymatic or indirect non-enzymatic actions and could affect the chemical nature of the radionuclides by altering the speciation, solubility and sorption properties and thus could increase or decrease the concentrations of radionuclides in solution. Fundamental understanding of the mechanisms of microbiological transformations of various chemical forms of uranium present in wastes and contaminated soils and water has led to the development of novel bioremediation processes. One process uses anaerobic bacteria to stabilize the radionuclides by reductive precipitation from higher to lower oxidation state with a concurrent reduction in volume due to the dissolution and removal of nontoxic elements from the waste matrix. In an another process, uranium and other toxic metals are removed from contaminated surfaces, soils, and wastes by extracting with the chelating agent citric acid. Uranium is recovered from the citric acid extract after biodegradation followed by photodegradation in a concentrated form as UO{sub 3} {center_dot} 2H{sub 2}O for recycling or appropriate disposal. These processes use all naturally occurring materials, common soil bacteria, naturally occurring organic compound citric acid and sunlight.

  12. Sound pressure distribution within natural and artificial human ear canals: Forward stimulation

    PubMed Central

    Ravicz, Michael E.; Tao Cheng, Jeffrey; Rosowski, John J.

    2014-01-01

    This work is part of a study of the interaction of sound pressure in the ear canal (EC) with tympanic membrane (TM) surface displacement. Sound pressures were measured with 0.5–2 mm spacing at three locations within the shortened natural EC or an artificial EC in human temporal bones: near the TM surface, within the tympanic ring plane, and in a plane transverse to the long axis of the EC. Sound pressure was also measured at 2-mm intervals along the long EC axis. The sound field is described well by the size and direction of planar sound pressure gradients, the location and orientation of standing-wave nodal lines, and the location of longitudinal standing waves along the EC axis. Standing-wave nodal lines perpendicular to the long EC axis are present on the TM surface >11–16 kHz in the natural or artificial EC. The range of sound pressures was larger in the tympanic ring plane than at the TM surface or in the transverse EC plane. Longitudinal standing-wave patterns were stretched. The tympanic-ring sound field is a useful approximation of the TM sound field, and the artificial EC approximates the natural EC. PMID:25480061

  13. Principles of landscape-geochemical studies in the zones contaminated by technogenical radionuclides for ecological and geochemical mapping

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Romanov, Sergey

    2013-04-01

    Efficiency of landscape-geochemical approach was proved to be helpful in spatial and temporal evaluation of the Chernobyl radionuclide distribution in the environment. The peculiarity of such approach is in hierarchical consideration of factors responsible for radionuclide redistribution and behavior in a system of inter-incorporated landscape-geochemical structures of the local and regional scales with due regard to the density of the initial fallout and patterns of radionuclide migration in soil-water-plant systems. The approach has been applied in the studies of distribution of Cs-137, Sr-90 and some other radionuclides in soils and vegetation cover and in evaluation of contribution of the stable iodine supply in soils to spatial variation of risk of thyroid cancer in areas subjected to radioiodine contamination after the Chernobyl accident. The main feature of the proposed approach is simultaneous consideration of two types of spatial heterogeneities: firstly, the inhomogeneity of external radiation exposure due to a complex structure of the contamination field, and, secondly, the landscape geochemical heterogeneity of the affected area, so that the resultant effect of radionuclide impact could significantly vary in space. The main idea of risk assessment in this respect was to reproduce as accurately as possible the result of interference of two surfaces in the form of risk map. The approach, although it demands to overcome a number of methodological difficulties, allows to solve the problems associated with spatially adequate protection of the affected population and optimization of the use of contaminated areas. In general it can serve the basis for development of the idea of the two-level structure of modern radiobiogeochemical provinces formed by superposition of the natural geochemical structures and the fields of technogenic contamination accompanied by the corresponding peculiar and integral biological reactions.

  14. Small turbines in distributed utility application: Natural gas pressure supply requirements

    SciTech Connect

    Goldstein, H.L.

    1996-05-01

    Implementing distributed utility can strengthen the local distribution system and help avoid or delay the expense of upgrading transformers and feeders. The gas turbine-generator set is an attractive option based on its low front-end capital cost, reliable performance at unmanned stations, and environmental performance characteristics. This report assesses gas turbine utilization issues from a perspective of fuel supply pressure requirements and discusses both cost and operational factors. A primary operational consideration for siting gas turbines on the electric distribution system is whether the local gas distribution company can supply gas at the required pressure. Currently available gas turbine engines require gas supply pressures of at least 150 pounds per square inch gauge, more typically, 250 to 350 psig. Few LDCs maintain line pressure in excess of 125 psig. One option for meeting the gas pressure requirements is to upgrade or extend an existing pipeline and connect that pipeline to a high-pressure supply source, such as an interstate transmission line. However, constructing new pipeline is expensive, and the small volume of gas required by the turbine for the application offers little incentive for the LDC to provide this service. Another way to meet gas pressure requirements is to boost the compression of the fuel gas at the gas turbine site. Fuel gas booster compressors are readily available as stand-alone units and can satisfactorily increase the supply pressure to meet the turbine engine requirement. However, the life-cycle costs of this equipment are not inconsequential, and maintenance and reliability issues for boosters in this application are questionable and require further study. These factors may make the gas turbine option a less attractive solution in DU applications than first indicated by just the $/kW capital cost. On the other hand, for some applications other DU technologies, such as photovoltaics, may be the more attractive option.

  15. Radionuclides in nephrology

    SciTech Connect

    Lausanne, A.B.D.

    1987-01-01

    In 47 expert contributions, this volume provides a summary of the latest research on radionuclides in nephro-urology together with current and new clinical applications especially in renovascular hypertension, kidney transplantation, and metabolic and urological diseases. In addition, attention is given to aspects of basic renal physiology and function and possible applications of nuclear magnetic resonance and spectroscopy in nephro-urology. New testing procedures which promise to improve diagnosis, and new radiopharmaceuticals are described. The reports are divided into eight sections, the first of which features studies on the renin-angiotensin system, cisplatin, atrial natriuretic factor and determining plasma oxalate. Four papers describe a number of new radiopharmaceuticals which have the potential to replace hippuran. In the third section, radionuclide methods for the measurement of renal function parameters are discussed. The book then focuses on the potential role of captopril in the improved diagnosis of renovascular hypertension. Applications of nuclear magnetic resonance and spectroscopy are demonstrated in the diagnosis of acute pyelonephritis, kidney assessment after lithotripsy, kidney evaluation prior to transplantation, and in monitoring renal ischemia during hypotension.

  16. Environmental and Genetic Influences of Archaeal Lipid Distribution in Natural and Artificial Marine Environments

    NASA Astrophysics Data System (ADS)

    Warren, C.; Pagani, M.

    2012-12-01

    TEX86 is a proxy of sea surface temperature based on refractory glycerol dibiphytanyl glycerol tetraethers (GDGT) in the cell membranes of low-temperature dwelling (non-hyperthermophilic) Archaea. The degree to which environmental signals other than temperature influence the distribution of GDGT compounds is poorly understood. Few representatives of the Thaumarchaeota — the clade to which the dominant GDGT production has been attributed — have been described or isolated in pure culture, and the role of genetic lineage in the synthesis and distribution of GDGTs is unknown. For this project we collected water, filter and substrate samples from tank systems in non-profit and commercial aquariums around the United States. This analysis compares GDGT core lipids and intact polar lipid distributions with Archaeal genetic sequence data processed using rRNA and 454 Pyrosequencing. Environmental attributes (such as dissolved oxygen concentration, salinity, organic density, etc.) specific to each tank are also compared to lipid analyses and the presence of specific lineages within select tank systems. Our preliminary results demonstrate that archaeal GDGTs are present and abundant within a range of environmental conditions, including artificial saline and brackish waters derived from municipal sources. Comparisons of existing TEX86 calibration values with known temperatures suggest that residuals vary based on non-temperature parameters. Branched compounds are absent in most aquarium systems, but dominate in systems prepared with municipal water.

  17. Effects on radionuclide concentrations by cement/ground-water interactions in support of performance assessment of low-level radioactive waste disposal facilities

    SciTech Connect

    Krupka, K.M.; Serne, R.J.

    1998-05-01

    The US Nuclear Regulatory Commission is developing a technical position document that provides guidance regarding the performance assessment of low-level radioactive waste disposal facilities. This guidance considers the effects that the chemistry of the vault disposal system may have on radionuclide release. The geochemistry of pore waters buffered by cementitious materials in the disposal system will be different from the local ground water. Therefore, the cement-buffered environment needs to be considered within the source term calculations if credit is taken for solubility limits and/or sorption of dissolved radionuclides within disposal units. A literature review was conducted on methods to model pore-water compositions resulting from reactions with cement, experimental studies of cement/water systems, natural analogue studies of cement and concrete, and radionuclide solubilities experimentally determined in cement pore waters. Based on this review, geochemical modeling was used to calculate maximum concentrations for americium, neptunium, nickel, plutonium, radium, strontium, thorium, and uranium for pore-water compositions buffered by cement and local ground-water. Another literature review was completed on radionuclide sorption behavior onto fresh cement/concrete where the pore water pH will be greater than or equal 10. Based on this review, a database was developed of preferred minimum distribution coefficient values for these radionuclides in cement/concrete environments.

  18. Seepage basin radionuclide transport in sediments and vegetation. Revision 1

    SciTech Connect

    Murphy, C.E. Jr.; Jerome, K.M.

    1993-12-31

    Radionuclide concentrations were measured in soil and vegetation growing adjacent to and in the Savannah River Laboratory Seepage Basins as part of the plan for closure of the basin system. The results of the measurements provide some information about the mobility of the radionuclides introduced into the basins. {sup 90}Sr is the most mobile of the radionuclides in soil. Its high mobility and high relative uptake by vegetation cause {sup 90}Sr to be distributed throughout the basin system. {sup 137}Cs is not as mobile in the basin soil, limiting its uptake by vegetation growing on the edge of the seepage basins; however, it is readily taken up by the vegetation growing in the basins. Soil mobility and vegetation uptake is relatively low for all of the transuranic radionuclides. For the most part these radionuclides remain near the surface of the basin soils where they were absorbed from the waste-water. The relative role of soil mobility and vegetation uptake on the distribution of radionuclide at the basins was futher evaluated by comparing the vegetation concentration ratio and the half-depth of penetration of the radionuclides in the basin soil. The results suggest that vegetation processes dominate in determining the concentration of {sup 60}Co and {sup 137}Cs in the vegetation. The influences of soil and vegetation are more balanced for {sup 90}Sr. The other radionuclides exhibit both low soil mobility and low vegetation uptake. The lack of soil mobility is seen in the lower concentrations found in vegetation growing on the edge of the basin compared to those growing in the basin.

  19. Radioactivity and lung cancer-mathematical models of radionuclide deposition in the human lungs

    PubMed Central

    Sturm, Robert

    2011-01-01

    The human respiratory tract is regarded as pathway for radionuclides and other hazardous airborne materials to enter the body. Radioactive particles inhaled and deposited in the lungs cause an irradiation of bronchial/alveolar tissues. At the worst, this results in a malignant cellular transformation and, as a consequence of that, the development of lung cancer. In general, naturally occurring radionuclides (e.g., 222Rn, 40K) are attached to so-called carrier aerosols. The aerodynamic diameters of such radioactively labeled particles generally vary between several nanometers (ultrafine particles) and few micrometers, whereby highest particle fractions adopt sizes around 100 nm. Theoretical simulations of radioactive particle deposition in the human lungs were based on a stochastic lung geometry and a particle transport/deposition model using the random-walk algorithm. Further a polydisperse carrier aerosol (diameter: 1 nm–10 µm, ρ ≈ 1 g cm−3) with irregularly shaped particles and the effect of breathing characteristics and certain respiratory parameters on the transport of radioactive particles to bronchial/alveolar tissues were considered. As clearly shown by the results of deposition modeling, distribution patterns of radiation doses mainly depend on the size of the carrier aerosol. Ultrafine (< 10 nm) and large (> 2 µm) aerosol particles are preferentially deposited in the extrathoracic and upper bronchial region, whereas aerosol particles with intermediate size (10 nm–2 µm) may penetrate to deeper lung regions, causing an enhanced damage of the alveolar tissue by the attached radionuclides. PMID:22263097

  20. Analysis on the threats and spatiotemporal distribution pattern of security in World Natural Heritage Sites.

    PubMed

    Wang, Zhaoguo; Yang, Zhaoping; Du, Xishihui

    2015-01-01

    World Natural Heritage Sites (WNHS) are treasures that need human protection and invite appreciation, which makes conservation of WNHS an urgent task. This paper assesses where in the world threats are most pressing and which WNHS require emergency assistance. Using an analysis of "hot spots" and inverse distance weighting, it finds that Africa is the region where WNHS are least secure. Reports of the state of the conservation of WNHS describe the many threats that exist. Of these, management activities and institutional factors are the primary threats. The paper suggests relevant measures to improve the WNHS security. PMID:25427826

  1. Assessment of the Nature, Distribution and Causes of Land Subsidence in Central and Northern Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Othman, A.; Sultan, M.; Al Harbi, H.; Youssef, A.; Ahmed, M.; Emil, M.; Zabramwi, Y.; Alzahrani, S.; Bahamil, A.; Chouinard, K.

    2014-12-01

    Numerous land subsidence events have been recently reported from central and northern parts of the Kingdom of Saudi Arabia in Hail, Al Qassim, Al Jowf, and Buraydah Provinces. In some cases, these incidences resulted in losses in life and property. In this study, an integrated (field, geologic, remote sensing) approach is applied to accomplish the following: (1) identify the spatial distribution and extent of areas affected by subsidence (TASK I), (2) identify the factor(s) causing such subsidence (TASK II), and (3) identify areas threatened by such phenomena across northern and central parts of the Kingdom using criteria extracted from TASK II (TASK III). A three-fold approach was applied: (1) visits were conducted to collect field observations from reported subsidence locations, (2) spatial correlations were implemented in a web-based GIS environment for the reported subsidence locations in relation to relevant co-registered static datasets (e.g., rock and soil types, geologic structures) and temporal datasets (e.g., groundwater extraction, landuse/landcover, distribution and magnitude of earthquakes), (3) subsidence rates were extracted applying the Small BAseline Subset (SBAS) radar interferometric technique and using European Remote Sensing satellite-1 (ERS-1), ERS-2, and the Environmental Satellite (Envisat) data sets. Our findings (from radar interferometric studies) indicate that the distribution of areas undergoing subsidence are consistent/correlate with: (1) reported subsidence locations, but reveal many additional unreported subsidence locations, (2) irrigated lands, especially those witnessing a progressive increase in agricultural activities with time; (3) outcrops of the Saq sandstone aquifer system, the main source for fresh groundwater in the Kingdom, (4) outcrops the Minjur limestone formation that are subject to karstification; and (5) urban centers lacking appropriate sewage and drainage systems.

  2. Reactor-Produced Medical Radionuclides

    SciTech Connect

    Mirzadeh, Saed; Mausner, Leonard; Garland, Marc A

    2011-01-01

    The therapeutic use of radionuclides in nuclear medicine, oncology and cardiology is the most rapidly growing use of medical radionuclides. Since most therapeutic radionuclides are neutron rich and decay by beta emission, they are reactor-produced. This chapter deals mainly with production approaches with neutrons. Neutron interactions with matter, neutron transmission and activation rates, and neutron spectra of nuclear reactors are discussed in some detail. Further, a short discussion of the neutron-energy dependence of cross sections, reaction rates in thermal reactors, cross section measurements and flux monitoring, and general equations governing the reactor production of radionuclides are presented. Finally, the chapter is concluded by providing a number of examples encompassing the various possible reaction routes for production of a number of medical radionuclides in a reactor.

  3. Transient natural ventilation of a room with a distributed heat source

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Shaun D.; Woods, Andrew W.

    We report on an experimental and theoretical study of the transient flows which develop as a naturally ventilated room adjusts from one temperature to another. We focus on a room heated from below by a uniform heat source, with both high- and low-level ventilation openings. Depending on the initial temperature of the room relative to (i) the final equilibrium temperature and (ii) the exterior temperature, three different modes of ventilation may develop. First, if the room temperature lies between the exterior and the equilibrium temperature, the interior remains well-mixed and gradually heats up to the equilibrium temperature. Secondly, if the room is initially warmer than the equilibrium temperature, then a thermal stratification develops in which the upper layer of originally hot air is displaced upwards by a lower layer of relatively cool inflowing air. At the interface, some mixing occurs owing to the effects of penetrative convection. Thirdly, if the room is initially cooler than the exterior, then on opening the vents, the original air is displaced downwards and a layer of ambient air deepens from above. As this lower layer drains, it is eventually heated to the ambient temperature, and is then able to mix into the overlying layer of external air, and the room becomes well-mixed. For each case, we present new laboratory experiments and compare these with some new quantitative models of the transient flows. We conclude by considering the implications of our work for natural ventilation of large auditoria.

  4. Halogenated Natural Products in Dolphins: Brain-Blubber Distribution and Comparison with Halogenated Flame Retardants.

    PubMed

    Barón, E; Hauler, C; Gallistl, C; Giménez, J; Gauffier, P; Castillo, J J; Fernández-Maldonado, C; de Stephanis, R; Vetter, W; Eljarrat, E; Barceló, D

    2015-08-01

    Halogenated natural products (MHC-1, TriBHD, TetraBHD, MeO-PBDEs, Q1, and related PMBPs) and halogenated flame retardants (PBDEs, HBB, Dec 602, Dec 603, and DP) in blubber and brain are reported from five Alboran Sea delphinids (Spain). Both HNPs and HFRs were detected in brain, implying that they are able to surpass the blood-brain barrier and reach the brain, which represents a new finding for some compounds, such as Q1 and PMBPs, MHC-1, TriBHD, TetraBHD, or Dec 603. Moreover, some compounds (TetraBHD, BDE-153, or HBB) presented higher levels in brain than in blubber. This study evidence the high concentrations of HNPs in the marine environment, especially in top predators. It shows the importance of further monitoring these natural compounds and evaluating their potential toxicity, when most studies focus on anthropogenic compounds only. While no bioaccumulation was found for ∑HNPs, ∑HFRs increased significantly with body size for both common and striped dolphins. Studies evaluating BBB permeation mechanisms of these compounds together with their potential neurotoxic effects in dolphins are recommended. PMID:26148182

  5. [Factors limiting distribution of the rare lichen species Lobaria pulmonaria (in forests of the Kologriv Forest Nature Reserve)].

    PubMed

    Ivanova, N V

    2015-01-01

    The distribution patterns and coenotic confines ofthe epiphytic lichen Lobaria pulmonaria have been studied. The factors limiting the habitat of this rare lichen species in the Kologriv Forest Nature Reserve (southern taiga subzone) have been revealed. It has been shown that L. pulmonaria is attracted to forest areas, which are less affected by humans and characterized by better light conditions than other communities. It has been found that L. pulmonaria is able to colonize trees at various ontogenetic states, beginning from virginal ones. PMID:26021161

  6. Comparison between natural Rain drop size distributions and corresponding models near equilibrium state during warm rain

    NASA Astrophysics Data System (ADS)

    Barthes, Laurent; Mallet, Cécile

    2010-05-01

    Keywords: Rain Drop Size Distribution, Breakup, coalescence, disdrometer The study of the vertical evolution of raindrop size distributions (DSDs) during rainfall, from the freezing level isotherm to ground level, is a key to improving our understanding of the microphysics of rain. In numerous domains such as remote sensing, telecommunications, soil erosion, and the study of the rain's efficiency in 'washing' the atmosphere, the DSD plays an important role. Among the different processes affecting the evolution of DSD, breakup and coalescence are two of the most significant. Models of coalescence and breakup lead to equilibrium of the raindrop size distribution (DSD) after a fall through sufficient vertical height. At equilibrium, the DSD no longer evolves, and its shape is unique whatever the rain rate or LWC. This implies that the DSD is known, to within a multiplication constant. These models based on experimental measurements have been developed over the past 40 years. The Low and List (1982a,b) parameterization (hereinafter LL82) and the Greg M. McFarquhar (2004) model are both based on the same laboratory experiments, which lead to an equilibrium drop size distribution (EDSD) with two or three peaks, and an exponential tail with a slope of approximately Λ=65 cm-1. Numerous measurements using disdrometer collected in different climatic areas: Paris, France (Mars to October 2000), Iowa-City (April to October 2002), and Djougou (Benin June to September 2006) corresponding to 537 hours of rain period have shown that for high rain rates, close to a state of equilibrium, this slope lies between Λ=20 - 22 cm-1. This latter value is corroborated by others measurements found in the literature (Hu & Srivastava, 1995). Hu & Srivastava suggested that the Low and List parameterization may overestimate the effects of the breakup process. This hypothesis is in adequation with recent laboratory experiments (A.P. Barros 2008) in which the authors conclude that the number of

  7. The distributions of one invasive and two native crayfishes in relation to coarse-scale natural and anthropogenic factors

    USGS Publications Warehouse

    Westhoff, J.T.; Rabeni, C.F.; Sowa, S.P.

    2011-01-01

    1. Native crayfishes are often extirpated from portions of their range because of interactions with invasive species, anthropogenic alterations to environmental conditions or a combination of these factors. Our goal was to identify coarse-scale natural and anthropogenic factors related to the current distributions of the invasive crayfish, Orconectes hylas, and two endemic crayfishes, Orconectes peruncus andOrconectes quadruncus in the St. Francis River drainage, Missouri, U.S.A. and to provide wider insights into the potential role of anthropogenic factors in facilitating species displacement. 2. We used classification trees to model coarse-scale natural and anthropogenic environmental factors and their relation to the presence or absence of each species. Model results were then used to predict probability of presence for each species within each stream segment throughout the entire St. Francis River drainage. 3. Factors related to geology and soils were the best predictors of species distributions. A dichotomy of these factors explained much of the discrete distributions of the two native species. Agricultural-related factors were identified as the most influential anthropogenic activity related to species distributions. All associations between the invasive species and anthropogenic factors were negative which suggested the invader was not likely to establish in heavily impacted areas. Overall, our models had high correct classification rates, and we were able to reliably predict the presence of the invader in the invaded drainage. 4. Given the negative associations of the invader with anthropogenic alterations at a coarse spatial scale, we believe other mechanisms are likely to be responsible for the widespread displacement of the two native species. These findings can be used to assist in conservation activities such as creation of refugia for native species and may direct future research to identify the mechanism(s) of species displacement.

  8. Spatio-temporal distribution and natural variation of metabolites in citrus fruits.

    PubMed

    Wang, Shouchuang; Tu, Hong; Wan, Jian; Chen, Wei; Liu, Xianqing; Luo, Jie; Xu, Juan; Zhang, Hongyan

    2016-05-15

    To study the natural variation and spatio-temporal accumulation of citrus metabolites, liquid chromatography tandem mass spectrometry (LC-MS) based metabolome analysis was performed on four fruit tissues (flavedo, albedo, segment membrane and juice sacs) and different Citrus species (lemon, pummelo and grapefruit, sweet orange and mandarin). Using a non-targeted metabolomics approach, more than 2000 metabolite signals were detected, from which more than 54 metabolites, including amino acids, flavonoids and limonoids, were identified/annotated. Differential accumulation patterns of both primary metabolites and secondary metabolites in various tissues and species were revealed by our study. Further investigation indicated that flavedo accumulates more flavonoids while juice sacs contain more amino acids. Besides this, cluster analysis based on the levels of metabolites detected in 47 individual Citrus accessions clearly grouped them into four distinct clusters: pummelos and grapefruits, lemons, sweet oranges and mandarins, while the cluster of pummelos and grapefruits lay distinctly apart from the other three species. PMID:26775938

  9. Distribution and Diversity of Symbiotic Thermophiles, Symbiobacterium thermophilum and Related Bacteria, in Natural Environments

    PubMed Central

    Ueda, Kenji; Ohno, Michiyo; Yamamoto, Kaori; Nara, Hanae; Mori, Yujiro; Shimada, Masafumi; Hayashi, Masahiko; Oida, Hanako; Terashima, Yuko; Nagata, Mitsuyo; Beppu, Teruhiko

    2001-01-01

    Symbiobacterium thermophilum is a tryptophanase-positive thermophile which shows normal growth only in coculture with its supporting bacteria. Analysis of the 16S rRNA gene (rDNA) indicated that the bacterium belongs to a novel phylogenetic branch at the outermost position of the gram-positive bacterial group without clustering to any other known genus. Here we describe the distribution and diversity of S. thermophilum and related bacteria in the environment. Thermostable tryptophanase activity and amplification of the specific 16S rDNA fragment were effectively employed to detect the presence of Symbiobacterium. Enrichment with kanamycin raised detection sensitivity. Mixed cultures of thermophiles containing Symbiobacterium species were frequently obtained from compost, soil, animal feces, and contents in the intestinal tracts, as well as feeds. Phylogenetic analysis and denaturing gradient gel electrophoresis of the specific 16S rDNA amplicons revealed a diversity of this group of bacteria in the environment. PMID:11525967

  10. Natural and human-induced sinkhole hazards in Saudi Arabia: distribution, investigation, causes and impacts

    NASA Astrophysics Data System (ADS)

    Youssef, Ahmed M.; Al-Harbi, Hasan M.; Gutiérrez, Francisco; Zabramwi, Yasser A.; Bulkhi, Ali B.; Zahrani, Saeed A.; Bahamil, Alaa M.; Zahrani, Ahmed J.; Otaibi, Zaam A.; El-Haddad, Bosy A.

    2015-11-01

    Approximately 60 % of the 2,150,000 km2 area of Saudi Arabia is underlain by soluble sediments (carbonate and evaporite rock formations, salt diapirs, sabkha deposits). Despite its hyper-arid climate, a wide variety of recent sinkholes have been reported in numerous areas, involving significant property losses. Human activities, most notably groundwater extraction, have induced unstable conditions on pre-existing cavities. This work provides an overview of the sinkhole hazard in Saudi Arabia, a scarcely explored topic. It identifies the main karst formations and the distribution of the most problematic sinkhole areas, illustrated through several case studies covering the wide spectrum of subsidence mechanisms. Some of the main investigation methods are presented through selected examples, including remote sensing, trenching and geophysics. Based on the available data, the main causal factors are identified and further actions that should be undertaken to better assess and manage the risk are discussed.

  11. Natural and human-induced sinkhole hazards in Saudi Arabia: distribution, investigation, causes and impacts

    NASA Astrophysics Data System (ADS)

    Youssef, Ahmed M.; Al-Harbi, Hasan M.; Gutiérrez, Francisco; Zabramwi, Yasser A.; Bulkhi, Ali B.; Zahrani, Saeed A.; Bahamil, Alaa M.; Zahrani, Ahmed J.; Otaibi, Zaam A.; El-Haddad, Bosy A.