A chemical survey of the Mississippi estuary     

Lewis E. Fox  Frederick Lipschultz  Lee Kerkhof  Steven C. Wofsy 《Estuaries and Coasts》1987,10(1):1-12

A “snap shot” survey of the Mississippi estuary was made during a period of low river discharge, when the estuarine mixing zone was within the deltaic channels. Concentrations of H⁺, Ca²⁺, inorganic phosphorus and inorganic carbon suggest that the waters of the river and the low salinity (<5‰) portion of the estuary are near saturation with respect to calcite and sedimentary calcium phosphate. An input of oxidized nitrogen species and N₂O was observed in the estuary between 0 and 4‰ salinity. The concentrations of dissolved NH₄ ⁺ and O₂, over most of the estuary, appeared to be influenced by decomposition of terrestrial organic matter in bottom sediments. The estuarine bottom also appears to be a source of CH₄ which has been suggested to originate from petroleum shipping and refining operations. Estuarine mixing with offshore Gulf waters was the dominant influence on distributions of dissolved species over most of the estuary (i.e., from salinities >5‰). The phytoplankton abundance (measured as chlorophylla) increased as the depth of the mixed layer decreased in a manner consistent with that expected for a light-limited ecosystem. Fluxes of NO₃ ^?+NO₂ ^? and soluble inorganic phosphorus to the Gulf of Mexico were estimated to be 3.4±0.2×10³ g N s^?1 and 1.9±0.2 g P s^?1 respectively, at the time of this study.  相似文献   

Geochemical characteristics of boninite series volcanics: implications for their source   总被引：2，自引：0，他引：2  

Rosemary L. Hickey  Frederick A. Frey 《Geochimica et cosmochimica acta》1982,46(11):2099-2115

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Inversion of interference hydraulic pumping tests in both homogeneous and fractal dual media     

Frederick Delay  Anne Kaczmaryk  Philippe Ackerer 《Advances in water resources》2007

This work proposes a complete method for automatic inversion of data from hydraulic interference pumping tests based on both homogeneous and fractal dual-medium approaches. The aim is to seek a new alternative concept able to interpret field data, identify macroscopic hydraulic parameters and therefore enhance the understanding of flow in porous fractured reservoirs. Because of its much contrasted sensitivities to parameters, the dual-medium approach yields an ill-posed inverse problem that requires a specific optimization procedure including the calculation of analytical sensitivities and their possible re-scaling. Once these constraints are fulfilled, the inversion proves accurate, provides unambiguous and reliable results. In the fractal context inverting several drawdown curves from different locations at the same time reveals more accurate. Finally, hydraulic parameters drawn from inversion should be taken into account to improve in various situations the conditioning of up-scaled flow in fractured rocks.  相似文献   

Effects of metals on the behaviour and oxygen consumption of the mud snail     

John R. MacInnes  Frederick P. Thurberg 《Marine pollution bulletin》1973,4(12):185-186

The behaviour and oxygen consumption rates of adult mud snails, exposed to five metals individually (arsenic, cadmium, copper, silver and zinc) and to one combination of two metals (cadmium and copper), have been examined. The oxygen uptake of distressed and retracted snails was found to be lower than that of controls after exposure to all individual metals except cadmium, which resulted in an elevation of oxygen consumption. The combination of copper and cadmium resulted in a lower rate than either metal alone.  相似文献   

Isotopic composition of oil-field brines from Kettleman North Dome,California, and their geologic implications     

Yousif K Kharaka  Frederick A.F Berry  Irving Friedman 《Geochimica et cosmochimica acta》1973,37(8):1899-1908

Deuterium and O¹⁸ analyses were made on 25 formation-water samples from Miocene (Temblor Formation) and Eocene (McAdams Formation) reservoir rocks at Kettleman North Dome oil field, California, and on three surface water samples from Reef Ridge located about three miles to the west of the field. The δO¹⁸ values obtained generally increase with depth and most probably are due to temperature controlled exchange reactions with carbonate cement and dissolved carbonate species. The δD values obtained seem to be controlled primarily by the membrane behavior of shales modifying the assumed original values. The contribution of isotopic exchange between water and clays cannot be evaluated at present.The isotopic data support the conclusions based on a detailed study of geology, hydrodynamics, and formation water geochemistry (Kharaka, 1971) which indicate that:1. The Temblor Formation waters are probably meteoric in origin concentrated chemically and isotopically by shale membranes, and 2. The McAdams Formation waters were most probably obtained by squeezing the original interstitial marine connate waters of deposition from the underlying Mesozoic sediments.  相似文献   

Decadal- to interannual-scale source water variations in the Caribbean Sea recorded by Puerto Rican coral radiocarbon     

K. Halimeda Kilbourne  Terrence M. Quinn  Thomas P. Guilderson  Robert S. Webb  Frederick W. Taylor 《Climate Dynamics》2007,29(1):51-62

Water that forms the Florida Current, and eventually the Gulf Stream, coalesces in the Caribbean from both subtropical and equatorial sources. The equatorial sources are made up of, in part, South Atlantic water moving northward and compensating for southward flow at depth related to meridional overturning circulation. Subtropical surface water contains relatively high amounts of radiocarbon (¹⁴C), whereas equatorial waters are influenced by the upwelling of low ¹⁴C water and have relatively low concentrations of ¹⁴C. We use a 250 year record of Δ¹⁴C in a coral from southwestern Puerto Rico along with previously published coral Δ¹⁴C records as tracers of subtropical and equatorial water mixing in the northern Caribbean. Data generated in this study and from other studies indicate that the influence of either of the two water masses can change considerably on interannual to interdecadal time scales. Variability due to ocean dynamics in this region is large relative to variability caused by atmospheric ¹⁴C changes, thus masking the Suess effect at this site. A mixing model produced using coral Δ¹⁴C illustrates the time varying proportion of equatorial versus subtropical waters in the northern Caribbean between 1963 and 1983. The results of the model are consistent with linkages between multidecadal thermal variability in the North Atlantic and meridional overturning circulation. Ekman transport changes related to tradewind variability are proposed as a possible mechanism to explain the observed switches between relatively low and high Δ¹⁴C values in the coral radiocarbon records.  相似文献   

Some current methods to represent the heterogeneity of natural media in hydrogeology   总被引：4，自引：0，他引：4  

G. de Marsily  F. Delay  V. Teles  M. T. Schafmeister 《Hydrogeology Journal》1998,6(1):115-130

We have known for a long time that the material properties of the subsurface are highly variable in space. We have learned that this variability is due to the extreme complexity and variation with time of processes responsible for the formation of the earth's crust, from plate tectonics to erosion, sediment transport, and deposition, as well as to mechanical, climatic, and diagenetic effects. As geologists, we learned how to "read" this complex history in the rocks and how to try to extrapolate in space what we have understood. As physicists, we then learned that to study flow processes in such media we must apply the laws of continuum mechanics. As mathematicians using analytical methods, we learned that we must simplify by dividing this complex continuum into a small number of units, such as aquifers and aquitards, and describe their properties by (constant) equivalent values. In recent years, as numerical modelers, we learned that we now have the freedom to "discretize" this complex reality and describe it as an ensemble of small homogeneous boxes of continuous media, each of which can have different properties. How do we use this freedom? Is there a need for it? If the answer is "yes," how can we assign different rock-property values to thousands or even millions of such little boxes in our models, to best represent reality, and include confidence levels for each selected rock property? As a tribute to Professor Eugene S. Simpson, with whom the first author of this paper often discussed these questions, we present an overview of three techniques that focus on one property, the rock permeability. We explain the motivation for describing spatial variability and illustrate how to do so by the geostatistical method, the Boolean method, and the genetic method. We discuss their advantages and disadvantages and indicate their present state of development. This is an active field of research and space is limited, so the review is certain to be incomplete, but we hope that it will encourage the development of new ideas and approaches.  相似文献   

Effects of large organic material on channel form and fluvial processes   总被引：1，自引：0，他引：1  

Edward A. Keller  Frederick J. Swanson 《地球表面变化过程与地形》1979,4(4):361-380

Stream channel development in forested areas is profoundly influenced by large organic debris (logs, limbs and rootwads greater than 10 cm in diameter) in the channels. In low gradient meandering streams large organic debris enters the channel through bank erosion, mass wasting, blowdown, and collapse of trees due to ice loading. In small streams large organic debris may locally influence channel morphology and sediment transport processes because the stream may not have the competency to redistribute the debris. In larger streams flowing water may move large organic debris, concentrating it into distinct accumulations (debris jams). Organic debris may greatly affect channel form and process by: increasing or decreasing stability of stream banks; influencing development of midchannel bars and short braided reaches; and facilitating, with other favourable circumstances, development of meander cutoffs. In steep gradient mountain streams organic debris may enter the channel by all the processes mentioned for low gradient streams. In addition, considerable debris may also enter the channel by way of debris avalanches or debris torrents. In small to intermediate size mountain streams with steep valley walls and little or no floodplain or flat valley floor, the effects of large organic debris on the fluvial processes and channel form may be very significant. Debris jams may locally accelerate or retard channel bed and bank erosion and/or deposition; create sites for significant sediment storage; and produce a stepped channel profile, herein referred to as ‘organic stepping’, which provides for variable channel morphology and flow conditions. The effect of live or dead trees anchored by rootwads into the stream bank may not only greatly retard bank erosion but also influence channel width and the development of small scour holes along the channel beneath tree roots. Once trees fall into the stream, their influence on the channel form and process may be quite different than when they were defending the banks, and, depending on the size of the debris, size of the stream, and many other factors, their effects range from insignificant to very important.  相似文献   

Respiratory response of cunners to silver     

Frederick P. Thurberg  Ries S. Collier 《Marine pollution bulletin》1977,8(2):40-41

Cunners, a common inshore teleost fish of the north-east coast of the United States, were exposed to various concentrations of silver for 96 h. At the end of this exposure period measurements of gill-tissue oxygen consumption were made. Significant respiratory depression was noted after exposure to concentrations as low as 0.12 ppm. These results are compared to those of similar studies using cadmium and mercury as the test metals.  相似文献   

Evaluation of an empirical orthogonal function–based method to downscale soil moisture patterns based on topographical attributes     

Frederick A. Busch  Jeffrey D. Niemann  Michael Coleman 《水文研究》2012,26(18):2696-2709

Soil moisture influences many hydrologic applications including agriculture, land management and flood prediction. Most remote‐sensing methods that estimate soil moisture produce coarse resolution patterns, so methods are required to downscale such patterns to the resolutions required by these applications (e.g. 10‐ to 30‐m grid cells). At such resolutions, topography is known to affect soil moisture patterns. Although methods have been proposed to downscale soil moisture based on topography, they usually require the availability of past high‐resolution soil moisture patterns from the application region. The objective of this article is to determine whether a single topographic‐based downscaling method can be used at multiple locations without relying on detailed local observations. The evaluated downscaling method is developed on the basis of empirical orthogonal function (EOF) analysis of space–time soil moisture data at a reference catchment. The most important EOFs are then estimated from topographic attributes, and the associated expansion coefficients are estimated on the basis of the spatial‐average soil moisture. To test the portability of this EOF‐based method, it is developed separately using four data sets (Tarrawarra, Tarrawarra 2, Cache la Poudre and Satellite Station), and the relationships that are derived from these data sets to estimate the EOFs and expansion coefficients are compared. In addition, each of these downscaling methods is applied not only for the catchment where it was developed but also to the other three catchments. The results suggest that the EOF downscaling method performs well for the location where it is developed, but its performance degrades when applied to other catchments. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献