Introduction of Hans Peter Eugster for the V. M. Goldschmidt Medal     

Donald L. Graf 《Geochimica et cosmochimica acta》1977,41(6):829-830

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Chemical osmosis,reverse chemical osmosis,and the origin of subsurface brines     

Donald L. Graf 《Geochimica et cosmochimica acta》1982,46(8):1431-1448

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Applied geomorphology. A perspective of the contribution of geomorphology to the interdisciplinary studies and environmental management | J.R. Hails (editor), 1977. Elsevier,Amsterdam, 418 pp., Dfl. 98.00, U.S. $ 39.95     

Wm. L. Graf 《Earth》1979,14(3):297-298

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Structural profile of the northwestern Caribbean     

W.P. DillonJ.G. Vedder  R.J. Graf 《Earth and Planetary Science Letters》1972

A seismic reflection and gravity profile across the continental margin of the Yucatan Peninsula, Yucatan Basin, Cayman Ridge, and Cayman Trough suggests that sediments in the Yucatan Basin consist of a thick succession of beds dominated by turbidites that overlie a thick but irregular sequence of beds, probably dominated by pelagic deposits. The so-called “Carib beds”, present elsewhere in the Caribbean, are not evident in the part of the basin crossed by this profile. The sedimentary section rests on a acoustic basement that probably represents the top of oceanic layer 2. A gravity model indicates that the crust beneath the Yucatan Basin is thin and therefore probably is oceanic in character. The crust thickens southward under the Cayman Ridge but thins again beneath the Cayman Trough. This local thickening is consistent with the suggestion that the Cayman Ridge is a rifted part of the Nicaraguan Rise.  相似文献   

Variable-density groundwater flow and solute transport in porous media containing nonuniform discrete fractures   总被引：1，自引：0，他引：1  

Thomas Graf  Ren Therrien 《Advances in water resources》2005,28(12):305-1367

Variations in fluid density can greatly affect fluid flow and solute transport in the subsurface. Heterogeneities such as fractures play a major role for the migration of variable-density fluids. Earlier modeling studies of density effects in fractured media were restricted to orthogonal fracture networks, consisting of only vertical and horizontal fractures. The present study addresses the phenomenon of 3D variable-density flow and transport in fractured porous media, where fractures of an arbitrary incline can occur. A general formulation of the body force vector is derived, which accounts for variable-density flow and transport in fractures of any orientation. Simulation results are presented that show the verification of the new model formulation, for the porous matrix and for inclined fractures. Simulations of variable-density flow and solute transport are then conducted for a single fracture, embedded in a porous matrix. The simulations show that density-driven flow in the fracture causes convective flow within the porous matrix and that the high-permeability fracture acts as a barrier for convection. Other simulations were run to investigate the influence of fracture incline on plume migration. Finally, tabular data of the tracer breakthrough curve in the inclined fracture is given to facilitate the verification of other codes.  相似文献   

Speciation and role of iron in cloud droplets at the puy de Dôme station     

Marius Parazols  Angela Marinoni  Pierre Amato  Otman Abida  Paolo Laj  Gilles Mailhot 《Journal of Atmospheric Chemistry》2006,54(3):267-281

Iron is the most abundant transition metal in the atmosphere and can play a significant role in cloudwater chemistry where its reactivity is closely related to the partitioning between Fe(II) and Fe(III). The objective of this work is to determine the total iron content and the iron speciation in a free tropospheric site, and to understand which factors influence these parameters. We collected 147 samples of cloudwater during 34 cloud events over a period of four years at the puy de Dôme summit. Besides iron we measured other chemical compounds, solar radiation, physico-chemical and meteorological parameters potentially connected with iron reactivity. The total iron concentrations ranged from 0.1 to 9.1 μM with the major frequency occurring at low levels. The pH and presence of organic complexants seem to be the most significant factors connected with total dissolved iron; while the iron oxidation state seems to be an independent factor. Light intensity, presence of complexants or oxidants (H₂O₂) do not influence the Fe(II)/Fe(Total) ratio, that was quite constant at about 0.75. This could be due to the potential redox that forces the Fe(II)-Fe(III) couple to the reduced form or, more probably to the complexation by Natural Organic Matter, that can stabilize iron in its reduced form and prevent further oxidation. Our field measurements did not show the diurnal cycle observed in surface water and predicted by models of atmospheric chemistry. This result prompts a more careful review of the role of iron and, by analogy, all the transition metals in atmospheric liquid phase, often over-estimated in the literature.  相似文献   

A Wetland Simulation Module for the MODFLOW Ground Water Model   总被引：8，自引：0，他引：8  

Jorge I. Restrepo  Angela M. Montoya  Jayantha Obeysekera 《Ground water》1998,36(5):764-770

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Absolute dating by uranium series disequilibrium of bones from the cave of La Chaise-de-Vouthon (Charente), France     

Angela M. Rae  Miro Ivanovich  Henry P. Schwarcz 《地球表面变化过程与地形》1987,12(5):543-550

Animal bones, associated with Palaeolithic artefacts and skeletal remains of early hominids from the cave of La Chaise-de-Vouthon, have been dated using a new approach to uranium series dating of bone. Speleothem (cave calcite) interstratified with bone-bearing sediments in the two chambers of Grotte Bourgeois-Delaunay and Grotte Suard have previously been dated by the ²³⁰Th/²³⁴ U method. This provides a chronological control for the bone ages, for which the method is still at an experimental stage. A good agreement is shown in most cases between the calcite and the bone ages, showing the cave to have been a stable environment for the deposition of bone and the acquisition of uranium.  相似文献   

Aerodynamic drag: Measured at a nearshore platform on lake of Geneva     

W. H. Graf  N. Merzi  C. Perrinjaquet 《Meteorology and Atmospheric Physics》1984,33(2-3):151-173

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Origin and significance of 13-hydroxychlorophyll derivatives in sediments     

J Stuart Walker  Angela H Squier  Dominic A Hodgson  Brendan J Keely   《Organic Geochemistry》2002,33(12)

The authenticity of hydroxychlorophyll derivatives in sediments has been verified by subjecting pure chlorophyll preparations to the extraction method used for sediments. Model studies of chlorophyll autoxidation reveal hydroxychlorophyll as the major product formed in the presence of hydrogen peroxide. Its stability to further oxidation implies that hydroxychlorophyll derivatives are not precursors of aetioporphyrins and are more likely to produce cycloalkanoporphyrins via the processes of diagenesis. The occurrence of 13²-hydroxyphaeophytin a throughout a sediment core from Loch Ness confirms it to be a widespread chlorophyll oxidation product formed during early diagenesis. Profiles of hydroxychlorophyll derivatives in a sediment core from an Antarctic lake demonstrate their potential for use as markers of oxidation processes in palaeoenvironmental assessment.  相似文献