The symmetry of the time and latitude problems     

C. A. Murray 《Journal of Geodesy》1961,59(1):69-77

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Metal-solid interactions in the marine environment: Estimating apparent equilibrium binding constants     

L.S. Balistrieri  J.W. Murray 《Geochimica et cosmochimica acta》1983,47(6):1091-1098

Surface chemistry concepts developed for heterogeneous oxide surfaces are illustrated with Cu, Cd, and Zn adsorption data on a well defined, model surface—goethite (αFeOOH)—and then applied to define the interaction or Zn with interfacial sediments from the Guatemala Basin at MANOP site H.Apparent equilibrium binding constants which describe metal associations with a surface, whose sites are composed of a spectrum of binding energies, are independent of adsorption density when sites are available in excess, but dependent on adsorption density when sites are limited. This conclusion makes it especially important to properly apply laboratory experimental results to describe adsorption processes in the natural environment. Therefore, a means for estimating the maximum adsorption density of an element on natural particles is discussed and used to estimate the quantity of Zn in interfacial sediments at MANOP site H which can be ascribed to the process of adsorption.  相似文献   

The Geomorphology of the Great Barrier Reef: Quaternary Development of Coral Reefs: D. Hopley. Wiley-Interscience,New York,N.Y., 1982, xiv + 453 pp., £stg. 45.00 (hardcover)     

R.C. Murray 《Sedimentary Geology》1983,36(1):65-66

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The use of electron backscatter diffraction and orientation contrast imaging as tools for sulphide textural studies: example from the Greens Creek deposit (Alaska)     

Katja?Freitag  Alan?P.?BoyleEmail author  Eric?Nelson  Murray?Hitzman  James?Churchill  Magda?Lopez-Pedrosa 《Mineralium Deposita》2004,39(1):103-113

The Greens Creek polymetallic massive sulphide deposit is hosted in a typical polyphase deformed lower greenschist facies orogenic setting. The structure of the host rocks is well constrained, exhibiting a series of three superimposed ductile deformations followed by two brittle episodes. The ore is found both in fold hinges where early-formed depositional features are preserved and in fold limbs where primary features are typically strongly modified or obliterated. Samples from both settings have been investigated using electron backscatter diffraction (EBSD) coupled with forescatter orientation contrast (OC) imaging in order to observe the effects of deformation and lower greenschist facies metamorphism on pyrite. Results suggest that colloform pyrite may preserve information relevant to palaeoenvironment, that apparently simple textures are generally more complex, and that pyrite can deform plastically by dislocation glide and creep processes at lower temperatures and/or strain rates than generally accepted. This analysis indicates that EBSD and OC imaging provide powerful tools for observing textural relationships in pyrite that are not shown by more traditional methods. They should become routine tools for pyrite texture analysis.Editorial handling: D. Lentz  相似文献   

Habitat requirements for submerged aquatic vegetation in Chesapeake Bay: Water quality, light regime, and physical-chemical factors   总被引：1，自引：0，他引：1  

W. Michael Kemp  Richard Batleson  Peter Bergstrom  Virginia Carter  Charles L. Gallegos  William Hunley  Lee Karrh  Evamaria W. Koch  Jurate M. Landwehr  Kenneth A. Moore  Laura Murray  Michael Naylor  Nancy B. Rybicki  J. Court Stevenson  David J. Wilcox 《Estuaries and Coasts》2004,27(3):363-377

We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing though the water column to the depth of SAV growth (PLW _min) and as a percentage of light reaching reaching leaves through the epiphyte layer (PLL _min). Value were computed by applying, as inputs to this algorithm, statistically dervived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates ofPLW _min andPLL _min compared well with the values established from a literature review. Calcultations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophylla (chla), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calculated light available at plant leaves exceededPLL _min. Predictions closely matched results of aerial photographic monitoring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polythaline regions, which contain 75–80% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide.  相似文献   

A GIS-Based Approach for Delineating Market Areas for Park and Ride Facilities     

Bilal Farhan  Alan T. Murray 《Transactions in GIS》2005,9(2):91-108

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A comparative analysis of eutrophication patterns in a temperate coastal lagoon     

W. R. Boynton  L. Murray  J. D. Hagy  C. Stokes  W. M. Kemp 《Estuaries and Coasts》1996,19(2):408-421

The coastal bays and lagoons of Maryland extend the full length of the state's Atlantic coast and compose a substantial ecosystem at the land-sea margin that is characterized by shallow depth, a well-mixed water column, slow exchange with the coastal ocean, and minimal freshwater input from the land. For at least 25 years, various types of measurements have been made intermittently in these systems, but almost no effort has been made to determine if water quality or habitat conditions have changed over the years or if distinctive spatial gradients in these features have developed in response to changing land uses. The purpose of this work was to examine this fragmented database and determine if such patterns have emerged and how they may be related to land uses. Turbidity, dissolved inorganic phosphate, algal biomass, and primary production rates in most areas of the coastal bays followed a regular seasonal pattern, which was well correlated with water temperature. Nitrate concentrations were low (<5 μM), and only modestly higher in tributary creeks (<20 μM). Additionally, there was little indication of the spring bloom typical of river-dominated systems. There does appear to be a strong spatial gradient in water quality conditions (more eutrophic in the upper bays, especially in tributary creeks). Comparisons of water quality data collected between 1970 and 1991 indicate little temporal change in most areas and some small improvements in a few areas, probably related to decreases in point-source discharges. Seagrass communities were once extensive in these systems but at present are restricted to the eastern portion of the lower bays where water clarity is sufficient to support plant survival. Even in these areas, seagrass densities have recently decreased. Examination of diel dissolved oxygen data collected in the summer indicates progressively larger diel excursions from lower to upper bays and from open bays to tributary subsystems; however, hypoxic conditions (<2 mg 1^?1) were rarely observed in any location. Nitrogen input data (point, surface runoff, groundwater and atmospheric deposition to surface waters) were assembled for seven regions of the coastal bay system; annual loading rates ranged from 2.4 g N m^?2 yr^?1 to 39.7 g N m^?2 yr^?1. Compared with a sampling of loading rates to other coastal systems, those to the upper and lower bays were low while those to tributaries were moderate to high. Regression analysis indicated significant relationships between annual nitrogen loading rates and average annual total nitrogen and chlorophyll a concentrations in the water column. Similar analyses also indicated significant relationships between chlorophyll a and the magnitude of diel dissolved oxygen changes in the water column. It is concluded that these simple models, which could be improved with a well-designed monitoring program, could be used as quantitative management tools to relate habitat conditions to nutrient loading rates.  相似文献   

High (ground) water levels and dune development in central Australia: TL dates from gypsum and quartz dunes around Lake Lewis (Napperby), Northern Territory     

X. Y. Chen  J. Chappell  A. S. Murray 《Geomorphology》1995,11(4)

An episode of high lake levels prior to the last maximum glaciation has been identified at many localities in wastern Australia. Similar events have been recognized at playa lakes in central Australia, where gypsum dunes along playa margins formed during one or more episodes of high groundwater discharge, with a large influx of calcium sulphate.At Lake Lewis, exposures at two islands show similar sediment sequences: three pedogenic gypcrete layers interbedded with aeolian quartz and gypsum sand horizons form three units within gypsum dunes up to 7 m high. The lowest unit has cliffed edges buried by the upper units, indicating a significant time break. Four TL dates (coarse-grained quartz) show that this lowest unit was deposited at or before 70–80 ka. The middle unit of mixed gypsum and quartz sand capped by gypcrete represents the major phase of gypsum dune formation, and 6 TL dates range from 33 to 46 ka with overlapping error bars. These are slightly younger but statistically similar to TL dates (from 39 to 59 ka) of the shoreline gypsum dune at Lake Amadeus in the same region. The top unit of the two islands, up to 1 m thick, has not yet been well dated. One date is inconsistent with the well dated middle layer below, possibly because of incomplete bleaching, and has been rejected. The other date (17 ± 5 ka) is much younger which possibly indicates a minor and local reactivation of old gypsum sediments. At the lake margin, there are quartz dunes overlying the gypsum dunes, and a buried aeolian quartz sand layer occurs in a lake-margin terrace. These represent reactivation of the regional quartz dune field after the major gypsum dune formation. Two consistent TL dates (21 ± 4 ka and 23 ± 6 ka) indicate that regional dunes were active at about the time of the Last Glacial Maximum.  相似文献   

Helmut Erich Landsberg, 1906–1985     

J. Murray Mitchell 《Climatic change》1986,9(3):262-265

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Population movement studied at microscale: Experience and extrapolation     

Chapman M 《GeoJournal》1987,15(4):347-365

The context for this paper is the nature of generalization deriving from the study of particular cases of human behaviour. With specific reference to field research on population movement conducted amongst individuals, households, small groups, and village communities in third world societies, it challenges the convention that both generalization and extrapolation are based inevitably and exclusively on the number of cases or events subject to examination. An evaluation is made of the methodological aspects of four different studies of population mobility at microscale, undertaken between 1965 and 1977 in the Solomon Islands and northwest Thailand. On this basis, integrated field designs that incorporate a range of intersecting instruments are favoured for their technical flexibility and logical strength. With case studies of third world villages, market centres, and urban neighbourhoods, generalization and extrapolation is based on depth of understanding and the power of theoretical connections.  相似文献