Modeling Organic Contaminant Partitioning in Ground-Water Systems   总被引：1，自引：0，他引：1  

Cass T. Miller  Walter J. Weber  Jr. 《Ground water》1984,22(5):584-592

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DISCUSSION OF "Matrix Diffusion Effects on Contaminant Migration from an Injection Well in Fractured Sandstone," by Stan Feenstra, J. A. Cherry, E. A. Sudicky, and Zia Haq     

G. R. Walter 《Ground water》1984,22(6):786-787

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Kerogen,Insoluble Organic Matter from Sedimentary Rocks | B. Durand (Editor), 1980. Editions Technip,Paris, XXVIII + 519 pp., FF 490.00     

Walter H. Fertl 《Earth》1982,18(1):87-88

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A climate-related oxidizing event in deep-sea sediment from the Bering Sea     

James V. Gardner  Walter E. Dean  David H. Klise  Jack G. Baldauf 《Quaternary Research》1982,18(1):91-107

Many cores from the deep basins of the Bering Sea have a thin oxidized zone within otherwise reduced sediment. This oxidized zone began to form about 6000 yr ago and represents an interval of about 3200 yr. Mineralogically, the oxidized and reduced sediments are similar, but chemically they differ. Concentrations of Fe and C are lower, and concentrations of Mn, Ba, Co, Mo, and Ni are higher in the oxidized than in the reduced sediment. Mn is enriched about 10-fold in the oxidized zone relative to its concentration in the reduced sediment, Mo about threefold, and Ba, Co, and Ni about twofold. These data suggest that the oxidized zone developed diagenetically as the result of the balance between the flux of organic matter and the available dissolved oxygen in bottom and interstitial waters.We propose that the Bering Sea was substantially ice covered when global glacial conditions prevailed. during the transition to global interglacial conditions, seasonal meltwater from thawing sea ice formed a lens of fresh water that decreased organic productivity. During the winter seasons, however, sea ice reformed and caused downwelling of dense, oxygen-rich waters to recharge bottom waters. The combination of lower organic productivity and more oxygen-rich bottom water allowed oxidized sediment to accumulate. Once full interglacial conditions were established, the volume of sea ice produced was insufficient to affect either productivity or the supply of dissolved oxygen and so bottom conditions again became reducing.Similar events probably occurred during the onset of global glacial conditions, and similar oxidized layers probably formed at these times. Such oxidized zones are highly unstable, however, in a reducing environment and, once buried beyond the influence of bacterial and infaunal activities, are depleted of their available oxygen and converted to reduced sediment.  相似文献   

A Repeated Pulse Technique for Determining the Hydraulic Properties of Tight Formations   总被引：1，自引：0，他引：1  

G. R. Walter  G. M. Thompson 《Ground water》1982,20(2):186-193

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Zur Viruseliminierung bei Trinkwasseraufbereitungsverfahren     

St. Rüdiger  G. A. Bagdasaryan  H.-J. Dobberkau  R. Walter 《洁净——土壤、空气、水》1982,10(4):377-389

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Does the principle of special relativity really hold?     

Walter Petry 《Astrophysics and Space Science》1986,124(1):63-82

We start from a reference frame for which the pseudo-Euclidean geometry holds, i.e., all laws in have the form of special relativity. The geometry of a reference frame , moving with constant velocity with regard to , is received by using the well-known Galilei-transformation for the covariant space-time vector. In the geometry is different from the pseudo-Euclidean one, i.e., the principle of special relativity does not hold. The velocity of light in is direction dependent but the null result of the Michelson-Morley experiment is received. Several useful transformation formulae are given. In particular, we obtain the Marinov-transformation as transformation from the frame to , and conversely. Maxwell's equations and the equations of motion in the reference frame are given. The theory is applied to some examples, e.g., the Doppler effect, the Fizeau experiment, the field of a charged particle, etc. The method can be generalized to an accelerated reference frame .  相似文献   

Two Tephra Layers Bracketing Late Holocene Paleoecological Changes in Northern Germany     

Christel van den Bogaard  Walter Drfler  Rainer Glos  Marie-Jose Nadeau  Pieter M. Grootes  Helmut Erlenkeuser 《Quaternary Research》2002,57(3):314

Paleoecological records from two Holocene peat bogs in northern Germany are linked by two microscopic volcanic ash layers, correlated by petrology and geochemistry to explosive volcanism on Iceland. The younger “Microlite tephra” cannot be correlated to any known eruption, while the older tephra layer is identified as a deposit of the Hekla 3 eruption. The tephra layers are dated by an age–depth regression of accelerator mass spectrometry ¹⁴C ages that have been calibrated and combined in probability distributions. This procedure gives an age of 730–664 cal yr B.C. for the “Microlite tephra” event and 1087–1006 cal yr B.C. for the Hekla 3 event. Accordingly, the tephra layers were deposited during the late Bronze Age. At this time, human settlement slowly increased pressure on the environment, as indicated by changes in woodland pollen composition at the two bogs. The tephra-marker horizons further show that the palynologically defined transition from the Subboreal to the Subatlantic Period is synchronous in the investigated area. However, the macroscopic visible marker in peat, the change from fibrous to sapric peat, the “Schwarztorf-Weißtorf-Kontakt,” is asynchronous. Bog vegetation did not immediately react in unison to a climatic change at this pollen zone boundary; instead, the timing of vegetation change depended on the location within the bog.  相似文献   

Millennium Ecosystem Assessment; Brief Report on the First Technical Design Workshop     

Carlos F. Corvalan  Walter V. Reid 《Global Change & Human Health》2001,2(1):78-79

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Optical identifications of southern rosat EUV and soft X-ray sources     

David A. H. Buckley  Kazuhiro Sekiguchi  Darragh O'Donoghue  Walter W. Wargau 《Astrophysics and Space Science》1995,230(1-2):117-130

This paper discusses the first all-sky surveys of cosmic extreme ultra-violet and soft X-ray sources, discovered by ROSAT. Details of the surveys are presented, with comparisons made to previous selected surveys in the X-ray regime. The subsequent optical identification programs are described, and the major results summarized. We then discuss the main classes of EUV emitters: active chromosphere stars and hot white dwarfs, and describe the importance of EUV observations in understanding the astrophysics of these objects. Many bright, and relatively nearby, sources have been identified as hitherto unrecognized active stars, representing the extremes in chromospheric and coronal activity, be it binary or age related. Many new hot DA white dwarfs have also been indentified, and the most exciting result in this area is the discovery that significant traces of heavier elements (e.g. C, N, O, Si, Fe and Al) exist in their atmospheres, substantially increasing their EUV opacities. The importance of hot white dwarfs as standard candles in probing the local interstellar medium is also discussed. Miscellaneous counterparts (AGN, PNN, O-B stars and CVs) that make up the rest of the sample of EUV sources are also briefly mentioned. We finish with a discussion of the on-going ROSAT Galactic Plane Survey (RGPS) identification program.  相似文献