Simultaneous flow of water and solutes through geological membranes—I. Experimental investigation     

Yousif K. Kharaka  Frederick A.P. Berry 《Geochimica et cosmochimica acta》1973,37(12):2577-2603

The relative retardation by geological membranes of cations and anions generally present in subsurface waters was investigated using a high pressure and high temperature ‘filtration cell’. The solutions were forced through different clays and a disaggregated shale subjected to compaction pressures up to 9500 psi and to temperatures from 20 to 70°C.The overall efficiences measured increased with increase of exchange capacity of the material used and with decrease in concentration of the input solution. The efficiency of a given membrane increased with increasing compaction pressure but decreased slightly at higher temperatures for solutions of the same ionic concentration.The results further show that geological membranes are specific for different dissolved species. The retardation sequences varied depending on the material used and on experimental conditions. The sequences for monovalent and divalent cations at laboratory temperatures were generally as follows: Li < Na < NH₃ < K < Rb < Cs Mg < Ca < Sr < Ba.The sequences for anions at room temperature were variable, but at 70°C, the sequence was: HCO₃ < I < B < SO₄ < Cl < Br.Monovalent cations contrary to some field data were generally retarded with respect to divalent cations. The differences in the filtration ratios among the divalent cations were smaller than those between the monovalent cations. The passage rate of B, HCO₃, I and NH₃ was greatly increased at 70°C.  相似文献   

Seismic stratigraphy and sedimentation history of the East Mariana Basin,western Pacific     

Thomas H. Shipley  Jill M. Whitman  Frederick K. Duennebier  Lisa D. Petersen 《Earth and Planetary Science Letters》1983,64(2):257-275

An interpretation of the seismic stratigraphy and sedimentation history of the East Mariana Basin has been made using recently collected seismic reflection and refraction data. This Mesozoic(?) age basin, between the Marshall Islands and the Mariana Trench, is subdivided into three regions. The central region with about 1000 m of sediment probably records Jurassic to Late Cretaceous sedimentation of a pelagic biogenic and clay-rich section overlain by a thick section of mainly Cenozoic carbonates shed from nearby volcanic platforms. A western region is characterized by a thinner sediment cover and a shallower acoustic basement with a similar sedimentation history except that the upper section is thinner as a consequence of fewer nearby volcanic highs. Extensive Late Cretaceous mid-plate volcanics apparently masks the lower section and forms acoustic basement. The shallower eastern region (east of 157.5°E) contains WNW-trending ridges which may be either fracture zones or high-amplitude abyssal hills. The sedimentation appears controlled by the same factors as in the other regions but the area was bypassed by most Cenozoic basin-filling turbidites because of its elevation.The isostatistically corrected basement depths between the three regions suggest that the crust in the east may be substantially younger than in the rest of the East Mariana Basin, perhaps Cretaceous in age. This requires the existence of a tectonic boundary within the basin.  相似文献   

Sampling‐surface orientation and clast macrofabric in periglacial colluvium     

Susan&#x;W. S. Millar  Frederick E. Nelson 《地球表面变化过程与地形》2001,26(5):523-529

To isolate the influence of sampling‐surface orientation on the macrofabric of periglacial colluvial deposits, clast orientation measurements were obtained from seven paired horizontal and vertical exposures in turf‐banked solifluction lobes on Niwot Ridge, Colorado Front Range. Most samples form moderately strong, upslope‐plunging clusters aligned with the local slope orientation. Fabrics obtained from vertical faces were stronger than those from horizontal exposures in six of the pairs. Near‐horizontal sampling surfaces yield less biased results than vertical exposures, owing to operator perceptions, procedural difficulties, and the relative thinness of the layer affected by colluvial processes. Sampling procedures must be standardized before comparative studies of colluvium can yield reliable results. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

A regional approach to cultural preservation: A central american example     

Frederick W. Lange  C. Mario Molina 《Natural Resources Research》1997,6(2):137-149

The transition to democratic governments in Central America over the past decade, and the subsequent emergence of institutional mechanisms for regional cooperation have greatly increased the frequency and productivity of efforts for preservation of cultural patrimony. Both the archaeological and colonial data bases overlap modern political boundaries and regional collaboration in training, pubic education, curation and research is essential. Natural forces continually impact, and human economic forces (especially international tourism) increasingly impact cultural resources. Regional cooperation in the utilization of human resources is necessary to confront the management and salvage demands of major economic development projects, and rescue efforts following natural disasters. The development of policies and programs will be effective only if matched by the growth of cultural preservation professionals in each of the Central American republics. Finally, other art consuming nations in addition to the United States must begin to respect the cultural heritage of the Central American countries and develop policies to deter abuses by diplomatic staff and employees of NGO’s (nongovernment organizations)  相似文献   

Use of radio-controlled miniature aircraft for marine atmosphere sampling     

Frederick R. Hess 《Marine Chemistry》1977,5(3):297-302

The use of Radio-Controlled Miniature aircraft by the Woods Hole Oceanographic Institution for obtaining marine air samples is discussed. The particular requirements for gaseous as well as large-volume particulate sampling are discussed and at-sea tests performed from the R/V “Knorr” are described. Handling and logistics of use as well as aircraft characteristics are discussed.  相似文献   

Isolated sensor Ocean Bottom Seismometer     

David A. Byrne  George H. Sutton  J. Grant Blackinton  Frederick K. Duennebier 《Marine Geophysical Researches》1983,5(4):437-449

In most of the Ocean Bottom Seisometers (OBS) used today, the sensors, electronics, recorders, flotation, and ballast are contained in one rigid package. Usually this configuration requires a large mass, a large vertical cross section in the water, and relatively small bearing surface area in contact with the bottom, resulting in poor seismic characteristics and increased noise sensitivity. An OBS recently developed at the Hawaii Institute of Geophysics (HIG) minimizes these problems by physically separating the sensor from the main OBS package. Direct comparison between signals recorded by a standard HIG configuration Pop-up Ocean Bottom Seismometer (POBS) and signals from the new Isolated Sensor Ocean Bottom Seismometer (ISOBS), deployed near each other in deep water, clearly demonstrates the advantages of the isolated sensor configuration. Although the ISOBS is superior to older OBS designs, recent testing suggests that further improvements can be made.  相似文献   

The vulcanicity of the lake district     

J. Frederick N. Green 《Proceedings of the Geologists' Association. Geologists' Association》1919,30(4):153-IN4

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The Geology of the Ordovician and Valentian rocks of the Shelve country,Shropshire     

Walter Frederick Whittard 《Proceedings of the Geologists' Association. Geologists' Association》1931,42(4):322-IN2

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Hydrographic characterization of two tidal creeks with implications for watershed land use,flushing times,and benthic production     

Christopher Buzzelli  A. Frederick Holland  Denise M. Sanger  Paul C. Conrads 《Estuaries and Coasts》2007,30(2):321-330

Many coastal ecosystems are undergoing anthropogenic stress from large increases in population and urbanization. In many regions changes in freshwater and material inputs to the coastal zone are altering the biogeochemical and biological capacities of ecosystems. Despite increased watershed inputs, large tidal volumes and flushing indicative of macrotidal estuaries can modulate the fate of introduced materials masking some of the symptoms of eutrophication. The Land Use Coastal Ecosystem Study (LU-CES) examined linkages between land use and environmental properties of Malind and Okatee Creeks in South Carolina from 2001 to 2004. The objectives of this particular study were to assess the hydrography of the two macrotidal creek ecosystems, explore differences in dissolved oxygen (DO), and develop a better understanding of the variations in primary and benthic secondary production in southeastern creek ecosystems. Depth, pH, salinity, and DO were reduced and more variable in Malind Creek than in Okatee Creek, although both creeks had strong semidiurnal frequencies in salinity time signatures. While time series analyses of DO saturation in Malind Creek revealed a dominant semidiurnal pattern, Okatee Creek had a distinctly diel DO pattern. The strongly semidiurnal fluctuations in DO and reduced flushing time indicated that biological processes were not fast enough to influence DO in Malind Creek. The Okatee Creek system had a much greater storage volume, a wider marsh, and a dominant 25-h DO frequency. These attributes contributed to an estimated 8–10 times more phytoplankton-based carbon in Okatee Creek and twice the annual benthic production. As expected from their proximity to the upland, low surface area, and high organic content, both ecosystems were net heterotrophic. This fundamental understanding of tidal creek hydrography is being used to help define linkages among differential watershed land uses, flushing characteristics, and levels of biological production in coastal ecosystems of the southeastern United States.  相似文献   

Iron/manganese ratio and manganese content in shield lavas from Ko’olau Volcano, Hawai’i     

Shichun Huang  Munir Humayun  Frederick A. Frey 《Geochimica et cosmochimica acta》2007,71(18):4557-4569

Precise Fe/Mn ratios and MnO contents have been determined for basalts from the Hawaiian shields of Ko’olau and Kilauea by inductively coupled plasma mass spectrometry. It is well known that the youngest Ko’olau (Makapu’u-stage) shield lavas define a geochemical endmember for Hawaiian lavas in terms of CaO and SiO₂ contents and isotopic ratios of O, Sr, Nd, Hf, Pb, and Os. We find that their MnO content is also distinct. Despite the small range in MnO, 0.146 to 0.176 wt%, the precision of our data is sufficient to show that among unaltered Ko’olau lavas MnO content is correlated with Nd-Hf-Pb isotopic ratios, La/Nb and Al₂O₃/CaO elemental ratios, and contents of SiO₂, MgO and Na₂O + K₂O adjusted for olivine fractionation. These trends are consistent with two-component mixing; one endmember is a SiO₂-rich, MnO-, and MgO-poor dacite or andesite melt, generated by low degree (10-20%) partial melting of eclogite. Since this low-MgO endmember (dacite or andesite melt) has very low FeO and MnO contents, mixing of high Fe/Mn dacite or andesite melt with a MgO-rich picritic melt, the other endmember, does not significantly increase the Fe/Mn in mixed magmas; consequently, Ko’olau and Kilauea lavas have similar Fe/Mn. We conclude that the high Fe/Mn in Hawaiian lavas relative to mid-ocean ridge basalt originates from the high MgO endmember in Hawaiian lavas.  相似文献