Respiration rates and hypoxia on the Louisiana shelf     

Quay Dortch  Nancy N. Rabalais  R. Eugene Turner  Gilbert T. Rowe 《Estuaries and Coasts》1994,17(4):862-872

The spatial and temporal variation in water-column respiration, estimated from enzymatic respiratory electron-transport-system activity, was measured monthly on a cross-shelf transect on the Louisiana shelf from May through October 1991. In July 1991, water-column respiration was also determined on an alongshore transect, and in situ benthic respiration and photosynthesis rates were determined at jour stations on the cross-shelf transect. Bottom waters were persistently hypoxic (O₂<2 mg 1^?1) at most stations in July and August and sporadically hypoxic at other times. Water-column respiration rates were in the same range as earlier, less extensive studies and not unusually high for coastal and estuarine waters. They were highest in summer, decreased with distance offshore and depth, and increased with temperature. Their variation with pigment and oxygen concentrations were complex functions of season and depth. Oxygen depletion below the oxycline could occur within days to months, depending on the season and location. In July, benthic respiration rates were also not unusually high in comparison with other shallow sediments, although the ratio of benthic: total (water column+benthic) respiration was high. Combined water-column and benthic respiration could deplete the bottom water oxygen in approximately 1 mo. Because the system rarely goes anoxic (defined as observing sulfide), some mechanism(s) must exist to reaerate bottom waters. Most physical mechanisms are unlikely to provide significant reaeration at this time of year. Measured benthic and conservatively estimated bottom-water photosynthesis could resupply 23% of the oxygen lost daily by respiration. Although this is too limited a dataset from which to draw conclusions about the relative importance of bottom-water and benthic respiration and photosynthesis in determining bottom-water oxygen concentrations, it does suggest that all these processes must be considered.  相似文献   

Internal secular variability in an ocean general circulation model   总被引：2，自引：1，他引：2  

Uwe Mikolajewicz  Ernst Maier-Reimer 《Climate Dynamics》1990,4(3):145-156

We describe results of an experiment in which the Hamburg Large-Scale Geostrophic Ocean General Circulation Model was driven by a spatially correlated white-noise freshwater flux superimposed on the climatological fluxes. In addition to the red-noise character of the oceanic response, the model exhibits pronounced variability in a frequency band around 320 years. The centers of action of this oscillation are the Southern Ocean and the Atlantic.This paper was presented at the International Conference on Modelling of Global Climate Change and Variability, held in Hamburg 11–15 September 1989 under the auspices of the Meteorological Institute of the University of Hamburg and the Max Planck Institute for Meteorology. Guest Editor for these papers is Dr. L. Dümenil.  相似文献   

Der Sierra Nevada-Pluton     

Ernst Cloos 《International Journal of Earth Sciences》1931,22(6):372-384

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Tief eneinschlüsse der Basalte     

Th. Ernst 《International Journal of Earth Sciences》1936,27(1):73-74

Ohne Zusammenfassung  相似文献   

Übersicht über die tektonische Entwicklung Albaniens     

Ernst Nowack 《International Journal of Earth Sciences》1929,20(2):96-107

Ohne Zusammenfassung  相似文献   

Zum siebzigjährigen Bestehen des deutschen Seehandbuchwerks     

Ernst Römer 《Ocean Dynamics》1948,1(5-6):202-203

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Die Olivinfels-Einsehlüsse der Basalte     

Theodor Ernst 《International Journal of Earth Sciences》1948,36(1):39-39

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Cenozoic Climates of the Great basin     

Ernst Antevs 《International Journal of Earth Sciences》1952,40(1):94-108

The Great Basin in the western United States consists of almost level desert basins and alternating parallel mountain ranges. It has sparse, mostly interior, drainage and a few permanent lakes. The climate is arid and semiarid. Fairly large areas are true deserts. The main Cenozoic climatic changes have been: 1. a general cooling during the Tertiary and the early Pleistocene, 2. a progressive drying from the early Miocene into the Pleistocene as a consequence of rise of the Sierra Nevada and the Cascades, and 3. Pleistocene fluctuations between cold-moist and warm-dry ages.The Ice Age left known records of three or four major glaciations, the last of which had two maxima. The glaciations were relatively extensive on the eastern flank of the Sierra Nevada and just east of the Great Basin, and glaciers existed on several ranges in northeastern Nevada. Each glacial was accompanied by a pluvial, which culminated just after the glacial maximum. The pluvial lakes were largest on Lat. 40°. The histories of the huge lakes Bonneville and Lahontan are incompletely known. During the Mankato-Tioga-Provo'glacio-pluvial maximum the temperature in the Great Basin seems to have been only 2.5–3 C° lower, and the precipitation on the surface of Lake Lahontan (Dendritic Lake) twice as large as now.The Neothermal (Postglacial, Postpluvial), the equivalent of the interglacials, is with long-distance correlation in view subdivided on the basis of the major temperature changes into the Ana-,.Alti-, and Medithermal ages. However, in the dry country of the Great Basin the changes in moisture are more apparent and important. The Altithermal was distinctly drier than the present, and nearly all the basins went dry. About 2000 B.C. several basins began again to contain lakes which remained permanent through some acute brief droughts. These recentmodern lakes attained very moderate maxima some time before Christ, while the glaciers in the adjacent mountains probably reached their greatest extent since the Anathermal during the last centuries.  相似文献   

Combined hydrodynamical and empirical modeling of ocean tides     

Ernst W. Schwiderski 《Marine Geophysical Researches》1984,7(1-2):215-229

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Heat flow and quantity of methane deduced from a gas hydrate field in the vicinity of the Dnieper Canyon,northwestern Black Sea   总被引：1，自引：1，他引：1  

Thomas?LüdmannEmail author  How?Kin?Wong  Philipp?Konerding  Matthias?Zillmer  J?rg?Petersen  Ernst?Flüh 《Geo-Marine Letters》2004,24(3):182-193

Seismic reflection data document for the first time the existence of a BSR in a limited area west of the Dnieper Canyon in the northwestern Black Sea. Seismic wide-angle data suggest that gas hydrates occupy in average 15±2% of the pore space in a zone of 100 m in thickness. A conservative quantification of the amount of methane associated with this gas hydrate occurrence is about 12±3×10¹¹ m³ (0.6±0.2 Gt of methane carbon). Conductive heat flow deduced from the BSR depth is in the range of 21±6 to 55±15 mW m^–2.  相似文献