Oyster (Crassostrea virginica,Gmelin) spat settlement and copper in aufwuchs     

Harriette L. Phelps  Joseph A. Mihursky 《Estuaries and Coasts》1986,9(2):127-132

Oysters from paired sites of high and low spatfall at three mid-Chesapeake Bay locations were analyzed for tissue copper and tissue zinc as well as copper in aufwuchs scraped from the upper (right valve) shell surface. Paired sites had no significant differences in oyster tissue copper, aufwuchs copper or oyster tissue copper-zinc ratio. In the laboratory, natural aufwuchs material on oyster shell rapidly concentrated copper up to 10× from copper-enriched estuarine water, with a partition coefficient (Ka) of 0.640 I kg^?1. Aufwuchs-sorbed copper resisted depuration, suggesting a strong metal-binding substance in aufwuchs material. Eyed veliger oyster larvae (setting stage) exposed to oyster shell fragments having copper-enriched aufwuchs showed normal setting preference for bottoms and edges of shell surfaces but a slight decrease in total set with increasing aufwuchs copper concentration. Settled oyster spat died or failed metamorphosis with LD50=534 μg Cu g^?1 aufwuchs. Since mid-Bay aufwuchs copper concentrations averaged 35.5 μg^?1, ranging up to 103 μg g^?1, oyster spatfall probably is not affected solely by present natural aufwuchs copper concentrations, but the potential for problems exists.  相似文献   

Potential for Solute Retardation on Monitoring Well Sand Packs and Its Effect on Purging Requirements for Ground Water Sampling   总被引：1，自引：0，他引：1  

Carl D. Palmer  Joseph F. Keely  William Fish 《Ground Water Monitoring & Remediation》1987,7(2):40-47

Monitoring well sand packs are theoretically capable of retarding metal ions and organic contaminants. If this retardation does indeed occur it may have a significant effect on the purging requirements of newly installed monitoring wells. Calculations based on mass balance and retardation concepts demonstrate that if common guidelines for well purging are followed, contaminants may not be detected or may be detected in lower concentrations than are actually present in the ground water. This problem is greatest in relatively shallow wells installed in low to moderate permeability materials. In most cases, the effect of solute retardation in the sand pack can be avoided simply by additional purging prior to the first sampling of the monitoring well. Common purging guidelines can then be applied to subsequent samplings. The methodology outlined in this paper can be used to calculate the purging requirements of existing monitoring wells or it may be applied to alternative monitoring well designs to test which will require the smallest volume of purged water.  相似文献   

Efficiency of kriging estimation for square, triangular, and hexagonal grids   总被引：8，自引：0，他引：8  

Evangelos A. Yfantis  George T. Flatman  Joseph V. Behar 《Mathematical Geology》1987,19(3):183-205

Although several researchers have pointed out some advantages and disadvantages of various soil sampling designs in the presence of spatial autocorrelation, a more detailed study is presented herein which examines the geometrical relationship of three sampling designs, namely the square, the equilateral triangle, and the regular hexagon. Both advantages and disadvantages exist in the use of these designs with respect to estimation of the semivariogram and their effect on the mean square error or variance of error. This research could be used to design optimal sampling strategies; it is based on the theory of regionalized variables, in which the intrinsic hypothesis is satisfied. Among alternative designs, an equilateral triangle design gives the most reliable estimate of the semivariogram. It also gives the minimum maximum mean square error of point estimation of the concentration over the other two designs for the same number of measurements when the nugget effect is small relative to the variance. If the nugget effect is large (.90 ² or more), and the linear sampling density is >0.85r where r is the range, the hexagonal design is best. This study computes and compares the maximum mean square error for each of these designs.  相似文献   

The Potential for Ground-Water Management in the West: A Symposium     

Joseph W. Westphal 《Ground water》1982,20(1):59-60

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HYDROLOGICAL INVESTIGATION OF HAZARDOUS WASTE LANDFILLS NEAR SOUTH CHARLESTON, WEST VIRGINIA     

Joseph L. Hughart 《Ground water》1982,20(3):349-349

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Paleomagnetic evidence for fossil biogenic magnetite in western Crete     

Joseph L. Kirschvink 《Earth and Planetary Science Letters》1982,59(2):388-392

Previous paleomagnetic research has shown that the concentration of fine-grained magnetite preserved in Miocene marine clays of western Crete drops during two successive geomagnetic transitions, although the mechanism responsible for this effect was not known. Magnetite precipitation by magnetotactic bacteria offers a straightforward explanation for this decrease. Reduced field strengths during a reversal will strain the competitive advantage of having intracellular magnetite and will force bacteria to precipitate correspondingly more magnetite if they are to maintain the same alignment in the geomagnetic field. Their ability to do this is limited by several magnetophysical constraints which should act to reduce the numbers of magnetite-precipitating cells, particularly in fields of less than about 12% of the present level. This would lead to a decrease in the supply of bacterial magnitude to the sediments. Recovery of intact magnetotactic bacterial fossils may lead to a new method for estimating paleointensities from sedimentary rocks.  相似文献   

Three-dimensional hybrid modelling of soil-structure interaction     

Sunil Gupta  Joseph Penzien  T. W. Lin  C. S. Yeh 《地震工程与结构动力学》1982,10(1):69-87

A three-dimensional hybrid model for the analysis of soil-structure interaction under dynamic conditions is developed which takes advantage of the desirable features of the finite element and substructure methods and which minimizes their undesirable features. The modelling is achieved by partitioning the total soil-structure system into a near-field and a far-field with a hemispherical interface. The near-field, which consists of the structure to be analysed and a finite region of soil around it, is modelled by finite elements. The semi-infinite far-field is modelled by distributed impedance functions at the interface which are determined by system identification methods. Numerical results indicate that the proposed model makes possible realistic and economical assessment of three-dimensional soil-structure interaction for both surface and embedded structures.  相似文献   

Transport of water in frozen soil: I: Experimental determination of soil-water diffusivity under isothermal conditions     

Yoshisuke Nakano  Allen Tice  Joseph Oliphant  Thomas Jenkins 《Advances in water resources》1982,5(4):221-226

A new experimental method for measuring the soil-water diffusivity of frozen soil under isothermal conditions is introduced. The theoretical justification of the method is presented and the feasibility of the method is demonstrated by experiments conducted using marine deposited clay. The measured values of the soil-water diffusivity are found comparable to reported experimental data.  相似文献   

FIELD APPLICATIONS OF CHEMICAL TIME-SERIES SAMPLING     

Joseph F. Keely  Fred Wolf 《Ground Water Monitoring & Remediation》1983,3(4):26-33

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Trace-element distribution in an active hydrothermal system, Roosevelt hot springs thermal area, Utah     

Odin D. Christensen  Regina A. Capuano  Joseph N. Moore 《Journal of Volcanology and Geothermal Research》1983,16(1-2)

Chemical interaction of thermal fluids with reservoir rock in the Roosevelt Hot Springs thermal area, Utah, has resulted in the development of characteristic trace-element dispersion patterns. Multielement analyses of surface rock samples, soil samples and drill cuttings from deep exploration wells provide a three-dimensional perspective of chemical redistribution within this structurally-controlled hot-water geothermal system.Five distinctive elemental suites of chemical enrichment are recognized, each characteristic of a particular combination of physical and chemical conditions within the geothermal system. These are: (1) concentrations of As, Sb, Be, and Hg associated with siliceous material at locations of liquid discharge, fluid mixing or boiling; (2) concentrations of Mn, Ba, W, Be, Cu, Co, As, Sb and Hg in manganese and iron oxide deposits; (3) high concentrations of Hg in argillized rock near fumaroles and lower concentrations in a broad diffuse halo surrounding the thermal center; (4) concentrations of As in sulfides and Li in silicate alteration minerals immediately surrounding high-temperature fluid flow-controlling fractures; (5) deposits of CaCO₃ at depth where flashing of brine to steam has occurred due to pressure release. The geochemical enrichments are not, in general, widespread, pervasively developed zones of regular form and dimension as are typical in many ore-forming hydrothermal systems.As the geothermal system develops, changes and eventually declines through time, the chemical deposits are developed, remobilized or superimposed upon each other, thus preserving within the rocks a record of the history of the geothermal system. Recognition of trace-element distribution patterns during the exploration of a geothermal system may aid definition of the present geometry and interpretation of the history of the system.  相似文献