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  • Articles  (1,109)
  • Chemistry  (1,094)
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  • Architecture, Civil Engineering, Surveying  (861)
  • Geosciences  (248)
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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of otolith chemistry in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS (1999)
    Springer
    Coral reefs 18 (1999), S. 171-178 
    Details
    ISSN: 1432-0975
    Keywords: Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380050176
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  • 2
    Electronic Resource
    Electronic Resource
    The importance of energetic particle precipitation on the chemical composition of the middle atmosphere (1980)
    Springer
    Pure and applied geophysics 118 (1980), S. 128-151 
    Details
    ISSN: 1420-9136
    Keywords: Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01586448
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  • 3
    Electronic Resource
    Electronic Resource
    Turbulent mixing of reactive gases in the convective boundary layer (1997)
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    Details
    ISSN: 1573-1472
    Keywords: Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000414710372
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  • 4
    Electronic Resource
    Electronic Resource
    Statistical considerations for grain-size analyses of tills (1971)
    Springer
    Mathematical geology 3 (1971), S. 227-238 
    Details
    ISSN: 1573-8868
    Keywords: classification ; data processing ; graphics ; mapping ; mathematics ; plotting ; sampling ; statistics ; sedimentology ; stratigraphy ; grain-size analysis ; textural analysis ; glacial geology ; Pleistocene stratigraphy ; till
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Relative percentages of sand, silt, and clay from samples of the same till unit are not identical because of different lithologies in the source areas, sorting in transport, random variation, and experimental error. Random variation and experimental error can be isolated from the other two as follows. For each particle-size class of each till unit, a standard population is determined by using a normally distributed, representative group of data. New measurements are compared with the standard population and, if they compare satisfactorily, the experimental error is not significant and random variation is within the expected range for the population. The outcome of the comparison depends on numerical criteria derived from a graphical method rather than on a more commonly used one-way analysis of variance with two treatments. If the number of samples and the standard deviation of the standard population are substituted in at-test equation, a family of hyperbolas is generated, each of which corresponds to a specific number of subsamples taken from each new sample. The axes of the graphs of the hyperbolas are the standard deviation of new measurements (horizontal axis) and the difference between the means of the new measurements and the standard population (vertical axis). The area between the two branches of each hyperbola corresponds to a satisfactory comparison between the new measurements and the standard population. Measurements from a new sample can be tested by plotting their standard deviation vs. difference in means on axes containing a hyperbola corresponding to the specific number of subsamples used. If the point lies between the branches of the hyperbola, the measurements are considered reliable. But if the point lies outside this region, the measurements are repeated. Because the critical segment of the hyperbola is approximately a straight line parallel to the horizontal axis, the test is simplified to a comparison between the means of the standard population and the means of the subsample. The minimum number of subsamples required to prove significant variation between samples caused by different lithologies in the source areas and sorting in transport can be determined directly from the graphical method. The minimum number of subsamples required is the maximum number to be run for economy of effort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02045793
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  • 5
    Electronic Resource
    Electronic Resource
    Momentum and energy balance equations for compacting sediments (1976)
    Springer
    Mathematical geology 8 (1976), S. 305-322 
    Details
    ISSN: 1573-8868
    Keywords: finite differences ; mathematics ; numerical analysis ; geophysics ; hydrology ; pressure ; temperature ; compacting sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Coupled energy and momentum balance equations are derived for a one-dimensional sequence of compacting sediments. These transient, nonlinear partial differential equations represent the one-dimensional equations of state for an accumulating sedimentary basin. A numerical solution is presented which provides a first-order approximation for porosity, temperature, and fluid pressures in the northern Gulf of Mexico. It seems that compaction disequilibrium is the primary mechanism for development of excess fluid pressures. Furthermore, the coupling of the equations demonstrates that temperature and pressure cannot be treated independently as may have been done in diagenetic studies. Some areas for further investigations are indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029275
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  • 6
    Electronic Resource
    Electronic Resource
    General equations for volume and surface area of a logarithmically coiled shell (1972)
    Springer
    Mathematical geology 4 (1972), S. 307-316 
    Details
    ISSN: 1573-8868
    Keywords: mathematics ; paleoecology ; paleontology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The equations of Moseley for the volume and surface area of a coiled shell have been rewritten in their most general forms. The general volume equation has been tested with 15 gastropods and found to give satisfactory results wherever there are no significant ontogenetic changes in the shell geometry. The equations provide a means for calculating the carbonate efficiency of a coiled shell. With this parameter analyzed into its component parts, it has been possible to understand the relationships between aspects of shell calcification and environmental factors that affect calcium carbonate availability. Preliminary studies indicate that it also may be possible to discriminate morphologically between terrestrial and aquatic gastropods, the various gastropod modes of life, and higher taxonomic categories. These equations offer possibilities for other studies concerned with the ecology, paleoecology, and evolution of coiled shells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02114092
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  • 7
    Electronic Resource
    Electronic Resource
    Rates of Geologic Processes: Problems for an Introductory Geology Course (2000)
    Springer
    Mathematical geology 32 (2000), S. 151-158 
    Details
    ISSN: 1573-8868
    Keywords: geologic education ; quantitative reasoning ; mathematics ; introductory geology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Geologic processes occur over a range of time scales. Introductory geology courses should provide students with an understanding of earth processes as well as the rates at which these processes operate. Three quantitative problems involving the rate of radioactive decay, the movement of groundwater pollution, and the rate of erosion in the Himalayas are described. These problems require students to graph data, understand units and orders of magnitude, manipulate equations, and put numerical answers into a broader geologic context.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007571205384
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  • 8
    Electronic Resource
    Electronic Resource
    A piecewise exponential model for seismic well-logging data (1974)
    Springer
    Mathematical geology 6 (1974), S. 33-45 
    Details
    ISSN: 1573-8868
    Keywords: inversion of data ; mathematics ; numerical analysis ; regression analysis ; geophysics ; petroleum ; well logging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Conventional methods of analyzing sonic log data do not always yield accurate information on each velocity segment of a well. It is shown here that the velocity-depth parameters and the sections of approximately constant velocity may be more precisely defined by using an exponential spline to model the data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02111925
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  • 9
    Electronic Resource
    Electronic Resource
    Quasifunctional equations for Ste. Genevieve Limestone facies and lithology (1974)
    Springer
    Mathematical geology 6 (1974), S. 107-115 
    Details
    ISSN: 1573-8868
    Keywords: functional equations ; mathematics ; numerical analysis ; rock description ; sedimentology ; stratigraphy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Equations describing ten microfacies of Ste. Genevieve Limestone established previously on qualitative analysis of petrographic features are derived here in terms of measured lithic parameters. Mean values of each lithic parameter for each facies comprise independent variables with eigenvalues from discriminant analysis serving as coefficients for quasifunctional equations. This provides a unique quantitative expression for each qualitative microfacies, the dependent variable. Although these equations are not truly functional equations, they do provide explicit description of Ste. Genevieve Limestone facies. Quasifunctional equations form a necessary first step toward establishment of true functional equations describing unit lithology as functions of depositional parameters. Functional equations for lithic units offer a potential for an ultimate unification of classifications for all geologic materials. An immediate value of these quasifunctional equations resides in their explicit description and identification of subjective lithic classifications (facies), their utilization in comparative studies of lithic components in one or more stratigraphie units, their facility for an objective and automated digital reduction and graphic presentation of data, and their invitation for more careful examination and critical evaluation of natural relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02080150
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  • 10
    Electronic Resource
    Electronic Resource
    Correspondence factor analysis: An outline of its method (1975)
    Springer
    Mathematical geology 7 (1975), S. 3-12 
    Details
    ISSN: 1573-8868
    Keywords: correspondence analysis ; factor analysis ; mathematics ; principal components ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Correspondence factor analysis is a multivariate technique that may be applied to any type of data and to any number of data points. It detects associations and oppositions existing between subjects and objects, measuring their contribution to the total inertia for each factor. The probabilistic character of the data matrix is taken into consideration, and together with the principle of distributional equivalence, results in stability. The projection of the subjects and the objects onto the same set of factorial axes enables two-dimensional graphs to be drawn which offer aid in the interpretation of the results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02080630
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