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Uranium removal in oceanic sediments and the oceanic U balance
269A
905114 Uranium removal in oceanic sediments and the oceanic U balance Barnes, C E; Cochran, J K Earth Planet Sei Lett 1/97, N1/2, Feb 1990, P94-101 Pore water uranium data have been collected from the NW Atlantic Ocean, Cariaco Trench, Black Sea, and San Ciemente basin. Fluxes across the sediment water interface were calculated. Results show depletion of pore water U relative to overlying water concentration. Uptake rate of U, derived from pore water gradients, reflects the redox environment, with lowest fluxes in oxic/suboxic sediments and highest in anoxic sediments. Fluxes are discussed in terms of oceanic U balance. It is estimated that about 65% of riverine U input is removed into ocean sediments, the remainder into altered oceanic crust.
905115 Critical reappraisal of colloidal activity of clays Pandian, N S; Nagaraj, T S J Geotech Engng Die ASCE VI16, N2, Feb 1990, P285-296 The physicochemical characteristics and relative proportions of constituent minerals have significant influence on soil properties. Atterberg limits and Skempton's colloidal activity, ACT (ratio of plasticity index and clay content), reflect composite effects of soil constituents and their interactions with pore fluids. Micromechanistic interpretations of these parameters are presented. It is demonstrated that in general liquid limit of fine grained soils reflects physicochemical potential, and that the factors of ACT are interdependent. Property correlations with ACT and Atterberg limits result in involved interrelations due to the interdependence of the parameters.
905116 Effect of moisture movement on tested thermal conductivity of moist materials Becker, R; Katz, A J Mater Civ Engng I/2, N2, May 1990, P72-83 Thermal conductivity is calculated on the basis of temperature gradients within the material under investigation. The gradient will cause moisture migration in unsaturated materials, and resulting apparent conductivity is smaller than the actual value. The dynamic processes and development of thermal and moisture fields during the test is analysed, and corrective procedures suggested. It is indicated that moisture migration is very small for most materials under normal test conditions. It becomes significant only at large temperature gradients or for highly vapour permeable but otherwise watertight materials such as hydrophobic thermal plasters.
905118 Experience gained with the thawing of seasonally frozen soils using a low-temperature plasma to install foundations Zadvornev, G A; Zarubin, B M; Berminov, A B; Lobanov, O V; Rabinovich, I G Soll Mech Found Engng V26, N2, March-April 1989, P41-44 Frozen soils must be thawed to allow installation of foundations in winter. A low temperature (3000-10000 deg C) plasma has been used for this purpose. Equipment employed is illustrated. Energy costs are less than one quarter of those of conventional electric heating and thaw time is much reduced. The thin layer of thermally compacted material formed during thaw is broken when trenches are tamped, and the hardened fragments embedded in the surrounding soft mass, improving trench wall stability.
905119 Contaminant accumulation during transport through porous media Gruber, J Water Resour Res V26, N1, Jan 1990, P99-107 The chemical environment changes as water infiltrates through geological materials, and the new chemical composition permeates through the medium. Adsorbed contaminants may desorb behind the front of the remobilizing wave. If the velocity of the front is intermediate between contaminant velocities up- and downstream of the front, remobilized contaminants may accumulate at the front. The behaviour of materials adsorbed on oxide particles under these conditions is discussed. Results suggest that pollution hazard cannot be assessed solely by contaminant adsorption isotherms but that remobilization effects must be included.
905120 Some observed effects of temperature variation on soil hehaviour Virdi, S P S; Keedwell, M J Proc International Conference on Rheology and Soil Mechanics, Coventry, 12-16 Sept 1988 P336-354. Publ London: Elsevier, 1988 Samples of uniform sand and kaolin clay were subjected to drained and undrained creep tests, triaxial consolidation, and strain controlled axial loading tests with imposed temperature variations. Effects of resulting expulsion/absorption of water or pore pressure rise/fall on time dependent behaviour are discussed. It is suggested that to avoid disturbance due to temperature variations, field samples should be transported in insulated containers and tested at in situ temperature.
905117 Rock physical properties: first results of the KTB-fieldlaboratory Lippmann, E; Bucker; C; Huenges, E; Rauen, A; Wienand, J; Wolter, K; Soffell, H C Sei Drilling VI, N3, 1989, P143-149
905121 Coastal muddy clay-marine clay. Strength improvement by electrochemical technique Pavate, T V Proc International Conference on Engineering Problems of Regional Soils, Beijing, 11-15 August 1988 P434-437. Publ Beijing: International Academic Publishers, 1989
Density, thermal and electrical conductivities, P and S wave velocities, porosity, radioactivity, magnetic properties, and stress relaxation were studied for cores from the Continental Deep Drilling (KTB) Project pilot hole. The field laboratory was set up to minimise the time for irrecoverable changes of cores before testing. Very small sampling intervals were used to enable variations with depth to be accurately followed. Observed anisotropies and depth variations are discussed with reference to geological and structural effects.
Highly saline coastal marine clays have high compressibility and low shear strength. Electroosmosis experiments under simulated tidal conditions are described. The clay system under study effectively became an altered medium consisting of separate acidic and alkaline compartments. Calcium and iron aluminosilicate gels formed around the cathode and led to significant permanent strength increases. The possible field use of this technique with salt injections away from the electrodes is discussed.
© 1990 Pergamon Press plc. Reproduction not permitted
905114 Uranium removal in oceanic sediments and the oceanic U balance Barnes, C E; Cochran, J K Earth Planet Sei Lett 1/97, N1/2, Feb 1990, P94-101 Pore water uranium data have been collected from the NW Atlantic Ocean, Cariaco Trench, Black Sea, and San Ciemente basin. Fluxes across the sediment water interface were calculated. Results show depletion of pore water U relative to overlying water concentration. Uptake rate of U, derived from pore water gradients, reflects the redox environment, with lowest fluxes in oxic/suboxic sediments and highest in anoxic sediments. Fluxes are discussed in terms of oceanic U balance. It is estimated that about 65% of riverine U input is removed into ocean sediments, the remainder into altered oceanic crust.
905115 Critical reappraisal of colloidal activity of clays Pandian, N S; Nagaraj, T S J Geotech Engng Die ASCE VI16, N2, Feb 1990, P285-296 The physicochemical characteristics and relative proportions of constituent minerals have significant influence on soil properties. Atterberg limits and Skempton's colloidal activity, ACT (ratio of plasticity index and clay content), reflect composite effects of soil constituents and their interactions with pore fluids. Micromechanistic interpretations of these parameters are presented. It is demonstrated that in general liquid limit of fine grained soils reflects physicochemical potential, and that the factors of ACT are interdependent. Property correlations with ACT and Atterberg limits result in involved interrelations due to the interdependence of the parameters.
905116 Effect of moisture movement on tested thermal conductivity of moist materials Becker, R; Katz, A J Mater Civ Engng I/2, N2, May 1990, P72-83 Thermal conductivity is calculated on the basis of temperature gradients within the material under investigation. The gradient will cause moisture migration in unsaturated materials, and resulting apparent conductivity is smaller than the actual value. The dynamic processes and development of thermal and moisture fields during the test is analysed, and corrective procedures suggested. It is indicated that moisture migration is very small for most materials under normal test conditions. It becomes significant only at large temperature gradients or for highly vapour permeable but otherwise watertight materials such as hydrophobic thermal plasters.
905118 Experience gained with the thawing of seasonally frozen soils using a low-temperature plasma to install foundations Zadvornev, G A; Zarubin, B M; Berminov, A B; Lobanov, O V; Rabinovich, I G Soll Mech Found Engng V26, N2, March-April 1989, P41-44 Frozen soils must be thawed to allow installation of foundations in winter. A low temperature (3000-10000 deg C) plasma has been used for this purpose. Equipment employed is illustrated. Energy costs are less than one quarter of those of conventional electric heating and thaw time is much reduced. The thin layer of thermally compacted material formed during thaw is broken when trenches are tamped, and the hardened fragments embedded in the surrounding soft mass, improving trench wall stability.
905119 Contaminant accumulation during transport through porous media Gruber, J Water Resour Res V26, N1, Jan 1990, P99-107 The chemical environment changes as water infiltrates through geological materials, and the new chemical composition permeates through the medium. Adsorbed contaminants may desorb behind the front of the remobilizing wave. If the velocity of the front is intermediate between contaminant velocities up- and downstream of the front, remobilized contaminants may accumulate at the front. The behaviour of materials adsorbed on oxide particles under these conditions is discussed. Results suggest that pollution hazard cannot be assessed solely by contaminant adsorption isotherms but that remobilization effects must be included.
905120 Some observed effects of temperature variation on soil hehaviour Virdi, S P S; Keedwell, M J Proc International Conference on Rheology and Soil Mechanics, Coventry, 12-16 Sept 1988 P336-354. Publ London: Elsevier, 1988 Samples of uniform sand and kaolin clay were subjected to drained and undrained creep tests, triaxial consolidation, and strain controlled axial loading tests with imposed temperature variations. Effects of resulting expulsion/absorption of water or pore pressure rise/fall on time dependent behaviour are discussed. It is suggested that to avoid disturbance due to temperature variations, field samples should be transported in insulated containers and tested at in situ temperature.
905117 Rock physical properties: first results of the KTB-fieldlaboratory Lippmann, E; Bucker; C; Huenges, E; Rauen, A; Wienand, J; Wolter, K; Soffell, H C Sei Drilling VI, N3, 1989, P143-149
905121 Coastal muddy clay-marine clay. Strength improvement by electrochemical technique Pavate, T V Proc International Conference on Engineering Problems of Regional Soils, Beijing, 11-15 August 1988 P434-437. Publ Beijing: International Academic Publishers, 1989
Density, thermal and electrical conductivities, P and S wave velocities, porosity, radioactivity, magnetic properties, and stress relaxation were studied for cores from the Continental Deep Drilling (KTB) Project pilot hole. The field laboratory was set up to minimise the time for irrecoverable changes of cores before testing. Very small sampling intervals were used to enable variations with depth to be accurately followed. Observed anisotropies and depth variations are discussed with reference to geological and structural effects.
Highly saline coastal marine clays have high compressibility and low shear strength. Electroosmosis experiments under simulated tidal conditions are described. The clay system under study effectively became an altered medium consisting of separate acidic and alkaline compartments. Calcium and iron aluminosilicate gels formed around the cathode and led to significant permanent strength increases. The possible field use of this technique with salt injections away from the electrodes is discussed.
© 1990 Pergamon Press plc. Reproduction not permitted