²¹⁰Po and ²¹⁰Pb distributions in ocean water profiles from the Eastern South Pacific     

John Thomson  Karl K. Turekian 《Earth and Planetary Science Letters》1976,32(2):297-303

Two ocean profiles from the Peru Basin from regions with different surface productivities were analyzed for total²¹⁰Pb and²⁰¹Po to evaluate the influence of particulates in the water column on their distribution. Comparison with a published²²⁶Ra profile for the region was made. The profile closest to the coast, where upwelling and productivity are high, shows depletion of²¹⁰Pb relative to²²⁶Ra at all depths, with particularly marked excursions from radioactive equilibrium at the surface and in the bottom water.²¹⁰Po appears to be deficient relative to²¹⁰Pb at depth as well. Mean residence times in the deep water, relative to particulate removal from the water column to the sediments, of about 100 years for²¹⁰Pb and about two years for²¹⁰Po are indicated. The profile northwest of the upwelling region shows the²²⁶Ra²¹⁰Pb²¹⁰Po system close to equilibrium at all depths to 1500 m (except for the effect of atmospheric²¹⁰Pb input seen at the surface.  相似文献   

Turnover of Eastern Caribbean deep water from ¹⁴C measurements     

Bruno Ribbat  Wolfgang Roether  Karl Otto Münnich 《Earth and Planetary Science Letters》1976,32(2):331-341

A¹⁴C balance for the Eastern Caribbean deep water indicates the average inflow of Atlantic water into the basin to be 2.3 × 10⁵ m³/sec (±30%), or about 2–4 times the values estimated previously. The balance uses a model representation of the deep-water turnover, and is based on¹⁴C concentrations at a station in the Venezuelan Basin which average Δ¹⁴C= 89‰ below 800 m depth with a total range of only 9‰, as well as on a¹⁴C concentration of the Atlantic inflow of Δ¹⁴C= ?71%. as obtained from measurements outside the Antilles Arch. The turnover time of the basin water below 2500 m depth is 55 years, which corresponds to an average upwelling velocity at this depth of about 35 m/year. With such upwelling, the temperature profile below 1800 m (the depth of the sill determining the inflow of new water) requires a vertical eddy diffusivity of about 5 cm²/sec. The oxygen consumption, and silica and CO₂ regeneration, rates below 2500 m depth are obtained as ?0.18, + 0.08, and + 0.2 μmole kg^?1 yr^?1, respectively. The CO₂ regeneration has but a negligible effect on the¹⁴C balance.  相似文献   

Paläoklimatische Information im Isotopengehalt14C-datierter Saharawässer: Kontinentaleffekt in D und18O     

Dr. Christian Sonntag  Prof. Dr. Eberhard Klitzsch  Prof. Dr. E. M. El Shazly  Christel Kalinke  Prof. Dr. Karl Otto Münnich 《International Journal of Earth Sciences》1978,67(2):413-423

Zusammenfassung In den¹⁴C-Altern der Saharawässer spiegelt sich die wechselnde Abfolge von Feucht- und Trockenphasen während des späten Pleistozäns und Holozäns wider. Außerdem zeigt sich ein West-Ost-Gefälle in ihrem D- und¹⁸O-Gehalt, das als Kontinentaleffekt im Grundwasser gedeutet wird. Dieser Kontinentaleffekt setzt voraus, daß das nordafrikanische Klimageschehen vergangener Feuchtphasen von der Westdrift bestimmt wurde, die regenbringende atlantische Luftmassen weit ins Saharainnere getrieben hat. Ein einfaches mathematisches Modell, das den Kontinentaleffekt durch eine Rayleigh-Kondensation beschreibt, ergibt die beste Anpassung an die Meßwerte, wenn für die Sahara (ähnlich wie heute in Europa) ein West-Ost-Gefälle in den Paläo-Winterniederschlagsmengen von –30% pro 1000 km angenommen wird. Unter der Annahme ehemaliger Winterniederschläge (Sept.-März) von 600 mm (entspricht Lissabon heute) für das Gebiet an der nordafrikanischen Atlantikküste ergibt diese Modellrechnung z. B. 250 mm für die Paläo-Winterniederschläge im Gebiet des Murzuk-Beckens.

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The¹⁴C-age distribution of Saharian groundwaters shows the alternating sequence of humid and arid periods in the late Pleistocene and Holocene. The observed west-east decrease of the D- and¹⁸O-content of the Sahara waters is interpreted to be the Continental Effect in rain and groundwater. The paleoclimatic situation during ground-water formation therefore was controlled by the western drift carrying wet Atlantic air masses across the Sahara. The best fit of a simple Rayleigh condensation model of the continental effect to the experimental data is obtained with a west-east decrease of the Saharian paleo-winter precipitation of –30% per 1000 km (similar to the one in Europe today). With an annual winter precipitation rate (Sept.-March) of 600 mm (corresponding to the one of Lisboa today) for the Northafrican coastal area at the Atlantic Ocean a previous winter precipitation rate of 250 mm is obtained for the Murzuq Basin.

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Résumé Une succession de périodes humides et arides à la fin du Pléistocène et à l'Holocène se réflète dans la distribution des âges¹⁴C d'eaux souterraines du Sahara. Les teneurs en D et¹⁸O diminuent d'Ouest en Est, ce qui est interprété comme un effet continental dans l'eau souterraine. Celui-ci signifie que la climatologie des phases pluviales passées, dans l'Afrique du Nord, était déterminée par des vents d'Ouest qui apportaient des masses d'air atlantique humide à l'intérieur du Sahara. Un modèle mathématique simple décrivant l'effet continental par une condensation du type Rayleigh, reproduit avec la meilleure conformité les valeurs expérimentales, pour autant qu'on admette que les pluies hivernales au Sahara diminuaient anciennement d'Ouest en Est de 30% par 1000 km (comme à présent en Europe). En supposant qu'autrefois la quantité de pluie hivernale, de septembre à mars à la côte atlantique de l'Afrique du Nord était de 600 mm (comme aujourd'hui à Lisbonne), on obtient à l'aide de ce modèle une précipitation hivernale ancienne de 250 mm dans le bassin du Mourzouk.

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, ¹⁴C, . , ¹⁸O, , . , , , , . , Rayleigh, — , — — 30 % 1000 . , - , . . , 600 , — —, 250 .

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Inhibited hatching success of marine fish eggs by power plant effluent     

Karl F Ehrlich 《Marine pollution bulletin》1977,8(10):228-229

The hatching success of California grunion (Leuresthes tenuis) was significantly reduced by a non-thermal component of the effluent from an electricity generating station. The embryos appeared to develop normally morphologically but showed reduced viability with respect to hatching.  相似文献   

Eastern Altantic fracture zones as potential disposal sites for radioactive waste     

Karl K. Turekian  Peter A. Rona 《Environmental Geology》1977,2(1):59-62

Disposal of radioactive waste in the sea floor of fracture zones associated with the flanks of the Mid-Atlantic Ridge may be a satisfactory alternative to land disposal. Effective physiographic, sedimentary, chemical, and oceanographic barriers exist in these aseismic deep canyons, especially in the eastern Atlantic. In addition, the major producers of radioactive wastes are likely to be near the Atlantic Ocean. If such a disposal strategy is adopted, intensive study of the sedimentologic and oceanographic properties of oceanic fracture zones will be necessary.  相似文献   

The Persian gulf: holocene carbonate sedimentation and diagenesis in a shallow epicontinental sea: B.H. PURSER, ed. (1973): 471 pp. 250 figs. and folding maps. Berlin—Heidelberg—New York: Springer Verlag. DM 66,-, US$ 29.80     

Karl Butzer  Curtis Larsen 《Geoforum》1974,5(4):104

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Sea level induced variations in clay mineral composition in the southwestern South China Sea over the past 17,000 yr     

Stephan Steinke  Till J.J. Hanebuth  Christoph Vogt  Karl Stattegger 《Marine Geology》2008,250(3-4):199-210

Variations in clay mineral composition of sediment cores from the margin and continental slope of the Sunda Shelf (southern South China Sea, SE Asia) covering the past 17,000 yr reflect changing influences of sediment sources together with clay mineral partitioning processes in shallow waters. We identify the deglacial sea level rise as the principal factor driving these changes. During the late glacial, high values of kaolinite are interpreted to reflect a higher contribution of clays from soils that have formed on the exposed Sunda Shelf and in the southern archipelagos of Indonesia. At this time core sites were located in close proximity to the mouths of the Sunda Shelf palaeo-drainage systems on the emerged shelf (“Sundaland”). The progressive landward displacement of the coastline and breakdown of these vast drainage systems during deglaciation led to a decrease in influence of the kaolinite-rich southern sources. When the coastline had retreated closely to its present-day position in mid-Holocene times, the former dominance of southern sources was replaced by a stronger influence of illite-rich sources (e.g. Borneo). The overriding control of sea level changes on the clay mineral distribution patterns precludes a definite climatic interpretation of clay mineral data in terms of climatic/monsoonal changes in such highly dynamic sedimentary environment.  相似文献   

The relationship between dissolved hydrogen and nitrogen fixation in ocean waters     

Robert M. Moore  Stephen Punshon  Claire Mahaffey  David Karl 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1449-1458

Fixed nitrogen is a key nutrient involved in regulating global marine productivity and hence the global oceanic carbon cycle. Oceanic nitrogen (N₂) fixation is estimated to supply 8×10¹² moles N y^?1 to the ocean, approximately equal to current riverine and the atmospheric inputs of fixed N, and between 50 and 100% of current estimates of oceanic denitrification. However, the spatial and temporal variability of N₂ fixation remains uncertain, mostly because of the normal low resolution sampling for diazotroph distribution and fixation rates. It is well established that N₂ fixation, mediated by the enzyme nitrogenase, is a source of hydrogen (H₂), but the extent to which it leads to supersaturation of H₂ in oceanic waters is unresolved. Here, we present simultaneous measurements of upper ocean dissolved H₂ concentration (nmol L^?1), and rates of N₂ fixation (μmol N m^?3 d^?1), determined using ¹⁵N₂ tracer techniques (at 7 or 15 m), on a transect from Fiji to Hawaii. We find a significant correlation (r=0.98) between dissolved H₂ and rates of N₂ fixation, with the greatest supersaturation of H₂ and highest rates of N₂ fixation being observed in the subtropical gyres at the southern (～18°S) and northern (18°N) reaches of the transect. The lowest H₂ saturation and N₂ fixation were observed in the equatorial region between 8°S and 14°N. We propose that an empirical relationship between H₂ supersaturations and N₂ fixation measurements could be used to guide sampling for ¹⁵N fixation measurements or to aid the spatial interpolation of such measurements.  相似文献   

Der Bau der rumänischen Ölgebiete     

Karl Krejci 《International Journal of Earth Sciences》1925,16(2):99-127

Ohne Zusammenfassung  相似文献   

Land use change and its ecological effect in Qian'an County of Jilin Province     

ZHONG Linsheng  ZHANG Yongmin  ZHAO Shidong  Karl E. Ryavec 《地理学报》2003,13(4):423-428

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors.　(3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability.  相似文献