Multivariate Geostatistïcal Analysis of Ground-Water Contamination: A Case History     

Jonathan D. Istok  Jeffrey D. Smyth  Alan L. Flint 《Ground water》1993,31(1):63-74

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Influence of Rhodamine WT Properties on Sorption and Transport in Subsurface Media   总被引：2，自引：0，他引：2  

Bor-Jier Shiau  David A. Sabatini  Jeffrey H. Harwell 《Ground water》1993,31(6):913-920

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A Numerical Model Study of Ground-Water Contamination from Price's Landfill, New Jersey— I. Data Base and Flow Simulation     

William G. Gray  Jeffrey L. Hoffman 《Ground water》1983,21(1):7-14

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Major and trace elements in igneous rocks from apollo 15     

Philip A. Helmke  Douglas P. Blanchard  Larry A. Haskin  Karen Telander  Charles Weiss  Jeffrey W. Jacobs 《Earth, Moon, and Planets》1973,8(1-2):129-148

The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na₂O, K₂O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow. At least two and possible three parent magmas can be identified from the samples of the quartz normative group on the basis of their concentration ratios of Sm to Eu. Within each group, the compositions of the samples appear to be related by crystallization of olivine or pyroxene. Significant variations of the ratio of concentration of Sm to Eu cannot be produced without plagioclase-liquid equilibrium. The source material of mare basalt may be depleted in Eu. Alternatively, the magmas may have assimilated a small volume of material similar to KREEP.Paper dedicated to Prof. Harold C. Urey on the occasion of his 80th birthday on 29 April 1973.  相似文献   

Ultraviolet spectroscopy of the outer layers of stars     

Theodore P. Snow Jr.  Jeffrey L. Linsky 《Astrophysics and Space Science》1980,67(2):285-307

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Physical and numerical modeling of reflections from interfaces and thin layers     

Fisher  D. Gardner  G. 《Oceanic Engineering, IEEE Journal of》1984,9(1):3-11

Basic models for understanding the reflection of seismic waves by the seafloor or the sublayering consist of isolated interfaces and isolated thin layers. An isolated interface model is used to demonstrate a reasonable agreement between physical modeling and two numerical solutions of the elastic wave equation. An isolated thin-layer model is used to show that reflections from it can be regarded as a scattered wavefield caused by three secondary sources proportional toDeltaM,-Deltamu, and,Deltarhoat each element of the layer, whereDelta, indicates the difference between the layer and the surroundings,Mis the compressional wave modulus,muis the shear wave modulus, andrhois the density. This viewpoint leads to a simple explanation of the observed variations in amplitude and phase of the reflected waves as the offset distance from source to receiver increases.  相似文献   

GIS-based hazard mapping and zonation of debris flows in Xiaojiang Basin,southwestern China   总被引：11，自引：0，他引：11  

Y.?P.?HeEmail author  H.?Xie  P.?Cui  F.?Q.?Wei  D.?L.?Zhong  J.?S.?Gardner 《Environmental Geology》2003,45(2):286-293

Debris flow sites were identified at 140 locations in the Xiaojiang Basin in Yunnan province, southwestern China. Their spatial distribution and catchment characteristics are described in detail on the basis of previous research, air photo interpretation, field investigation and mapping using Geographical Information Systems (GIS). Using a statistical approach, a quantitative model of hazards assessment and zonation was developed through synthesis analysis of basin areas, gradients, and the relative reliefs of these debris flow sites. In terms of debris flow hazard assessment, areas within the Xiaojiang Basin can be classified as severe, heavy and light hazard regions.  相似文献   

The response of fishes to submerged aquatic vegetation complexity in two ecoregions of the mid-Atlantic bight: Buzzards Bay and Chesapeake Bay     

Jason C. Wyda  Linda A. Deegan  Jeffrey E. Hughes  Melissa J. Weaver 《Estuaries and Coasts》2002,25(1):86-100

Estuarine seagrass ecosystems provide important habitat for fish and invertebrates and changes in these systems may alter their ability to support fish. The response of fish assemblages to alteration of eelgrass (Zostera marina) ecosystems in two ecoregions of the Mid-Atlantic Bight (Buzzards Bay and Chesapeake Bay) was evaluated by sampling historical eelgrass sites that currently span a broad range of stress and habitat quality. In two widely separated ecoregions with very different fish faunas, degradation and loss of submerged aquatic vegetation (SAV) habitat has lead to declines in fish standing stock and species richness. The abundance, biomass, and species richness of the fish assemblage were significantly higher at sites that have high levels of eelgrass habitat complexity (biomass >100 wet g m^?2; density <100 shotts m^?2) compared to sites that have reduced eelgrass (biomass <100 wet g m^?2; density <100 shoots m^?2) or that have completely lost eelgrass. Abundance, biomass, and species richness at reduced eelgrass complexity sites also were more variable than at high eelgrass complexity habitats. Low SAV complexity sites had higher proportions of pelagic species that are not dependent on benthic habitat structure for feeding or refuge. Most species had greater abundance and were found more frequently at sites that have eelgrass. The replacement of SAV habitats by benthic macroalgae, which occurred in Buzzards Bay but not Chesapeake Bay, did not provide an equivalent habitat to seagrass. Nutrient enrichment-related degradation of eelgrass habitat has diminished the overall capacity of estuaries to support fish populations.  相似文献   

Application of the luciferase cell culture bioassay for the detection of refined petroleum products   总被引：1，自引：0，他引：1  

Ziccardi MH  Gardner IA  Mazet JA  Denison MS 《Marine pollution bulletin》2002,44(10):983-991

A luciferase cell culture-based bioassay, developed to detect 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activity of halo-genated and polycyclic aromatic hydrocarbons, was optimized to detect refined petroleum products and to determine their relative inducing potency. Quality control standards from 32 refined products (gasolines and diesels, jet fuels, lubricating oils, fuel oils and weathered products) and three commercial products were evaluated. Induction equivalents (I-EQs) were determined by direct comparison of the EC50 and EC20 values (based on the median and 20% TCDD maximal response, respectively) from dose-response curves for each product to those obtained with TCDD. Most petroleum products were active in the luciferase bioassay, with those products composed of fractions produced later in the distillation process (i.e. fuel oils) inducing higher levels. Additionally, weathering of products reduced their induction potency. Based on the high I-EQ estimates of many products, biological effects associated with exposure may have been previously underestimated using other diagnostic methods.  相似文献   

Episodes of late Holocene aridity recorded by stalagmites from Devil's Icebox Cave, central Missouri, USA   总被引：1，自引：0，他引：1  

Rhawn F. Denniston  Michelle DuPree  Jeffrey A. Dorale  Victor J. Polyak 《Quaternary Research》2007,68(1):45-52

Two stalagmites from Devil's Icebox Cave, central Missouri, display similar δ¹³C and δ¹⁸O values and trends during the late Holocene. Positive δ¹³C excursions at 3.5-2.6 ka and 1.2-0.9 ka are interpreted to reflect drier conditions. These elevated stalagmite δ¹³C values could have plausibly been driven by increasing C₄ plant abundances over the cave or an increased contribution of bedrock carbon, both of which could reflect decreased effective moisture. A lack of corresponding oxygen isotopic anomalies during these intervals suggests that neither mean annual temperature nor the seasonality of precipitation changed concomitantly with dryness. Both of the δ¹³C excursions identified in our stalagmite record are roughly coincident with dry intervals from a number of sites located across the Great Plains.  相似文献