A partial instructional module on global and regional land use/cover change: assessing the data and searching for general relationships   总被引：4，自引：0，他引：4  

Susanne C. Moser 《GeoJournal》1996,39(3):241-283

Land use/cover change has occurred at all times in all parts of the world. Most affected and involved in these processes are the environmental spheres of water, soil, and vegetative cover, which are closely linked to geomorphology, climate, fauna, and especially human societies. These linkages between spheres are highly complex and, as of yet, incompletely understood. The most profound questions with respect to land use/cover and global change are: “What forces drive land use/land cover change?”, “What impacts — direct and indirect, now and in the future — do these changes have on the environment and on human society?” and “Can and should we, and if so, how, respond to these changes?” This partial teaching module, developed under the auspices of the Second Commission on College Geography of the Association of American Geographers, introduces students to the complexities inherent in these questions, but mainly focusses on the first of these. It illustrates the central role of the study of land land use/cover change within the large field of global environmental and climatic change, and is thus a good unit to introduce this area of interest.  相似文献   

Potential competition between hybrid striped bass (Morone saxatilis × M. americana) and striped bass (M. saxatilis) in the Cape Fear River estuary, North Carolina     

Wesley S. Patrick  Mary L. Moser 《Estuaries and Coasts》2001,24(3):425-429

Gillnet surveys from 1990 to 1992 and from 1996 to 1999 indicated a two-fold decrease in native striped bass (Morone saxatilis) populations and a concomitant two-fold increase in hybrid striped bass (Morone saxatilis × M. americana) in the Cape Fear River estuary, North Carolina. Gut content analysis indicated high diet overlap, and tagrecapture data suggested that hybrid striped bass participate in spawning migrations. These data provide circumstantial evidence that hybrid striped bass compete with striped bass for food and that they may compete for mates or habitat on the spawning grounds. Increasing abundance of adult hybrid striped bass in this system elevates the likelihood of hybrid introgression. We recommend that stocking of hybrid striped bass be terminated to preserve native striped bass populations.  相似文献   

Diatom-inference models for surface-water temperature and salinity developed from a 57-lake calibration set from the Sierra Nevada, California, USA   总被引：2，自引：0，他引：2  

Amy M. Bloom  Katrina A. Moser  David F. Porinchu  Glen M. MacDonald 《Journal of Paleolimnology》2003,29(2):235-255

Physical, chemical, and biological data were collected from a suite of 57 lakes that span an elevational gradient of 1360 m (2115 to 3475 m a.s.l.) in the eastern Sierra Nevada, California, USA as part of a multiproxy study aimed at developing transfer functions from which to infer past drought events. Multivariate statistical techniques, including canonical correspondence analysis (CCA), were used to determine the main environmental variables influencing diatom distributions in the study lakes. Lakewater depth, surface-water temperature, salinity, total Kjeldahl nitrogen, and total phosphorus were important variables in explaining variance in the diatom distributions. Weighted-averaging (WA) and weighted-averaging partial least squares (WA-PLS) were used to develop diatom-based surface-water temperature and salinity inference models. The two best diatom-inference models for surface-water temperature were developed using simple WA and inverse deshrinking. One model covered a larger surface-water temperature gradient (13.7 °C) and performed slightly poorer (r² = 0.72, RMSE = 1.4 °C, RMSEP_jack = 2.1 °C) than a second model, which covered a smaller gradient (9.5 °C) and performed slightly better (r² = 0.89, RMSE = 0.7 °C, RMSEP_jack = 1.5 °C). The best diatom-inference model for salinity was developed using WA-PLS with three components (r² = 0.96, RMSE = 4.06 mg L^–1, RMSEP_jack = 11.13 mg L^–1). These are presently the only diatom-based inference models for surface-water temperature and salinity developed for the southwestern United States. Application of these models to fossil-diatom assemblages preserved in Sierra Nevada lake sediments offers great potential for reconstructing a high-resolution time-series of Holocene and late Pleistocene climate and drought for California.  相似文献   

Dynamic and static compressibility of glasses and the increase of density with depth in the earth’s interior     

P. Moser  W. Kuhn  H. J. Kuhn 《Bulletin of Volcanology》1964,27(1):129-142

It is shown, using an organic and an inorganic glass, that, in a relaxing material, the compressibility consists of two parts, an instantaneous (dynamic) part and a delayed part. The instantaneous part amounts to about 2/3 of the total (static) compressibility. From consideration of relaxation times it is seen that, in the mantle of the earth, the density has to be calculated using the static compressibility, while seismic velocity curves give the dynamic value. Density curves are calculated on the basis of an essentially homogeneous earth interior derived from hot solar material.  相似文献   

Using environmental isotopes to investigate the groundwater recharge mechanisms and dynamics in the North-eastern Basin,Palestine     

Saed Khayat  Amer Marei  Dorothee Hippler  Zaher Barghouthi  Martin Dietzel 《水文科学杂志》2020,65(4):583-596

ABSTRACT

This study aims to differentiate the potential recharge areas and flow mechanisms in the North-eastern Basin, Palestine. The results differentiate the recharge into three main groups. The first is related to springs and some of the deep wells close to the Anabta Anticline, through the Upper Aquifer (Turonian) formation, with depleted δ¹⁸O and δ²H. The second is through the Upper Cenomanian formation surrounding the Rujeib Monocline in the southeast, where the lineament of the Faria Fault plays an important role, with relatively enriched δ¹³C_DIC values of about ?4‰ (VPDB). The third is the Jenin Sub-series, which shows higher δ¹³C_DIC values, with enriched δ¹⁸O and δ²H and more saline content. The deep wells from the Nablus area in the south of the basin indicate low δ¹³C_DIC values due to their proximity to freshwater infiltrating faults. The deep wells located to the northwest of the basin have δ¹³C_DIC values from ?8 to ?9‰ (VPDB), with enriched δ¹⁸O signatures, indicating slow recharge through thick soil.  相似文献   

Exhumation and relief history of the Southern Carpathians (Romania) as evaluated from apatite fission track chronology in crystalline basement and intramontane sedimentary rocks     

F. Moser  H. P. Hann  I. Dunkl  W. Frisch 《International Journal of Earth Sciences》2005,94(2):218-230

The combination of apatite fission track (FT) thermochronology from basement units and the FT age distributions of apatites in the Miocene intramontane sedimentary rocks allows describing the exhumation history of the central segment of the Southern Carpathians, Romania. Exhumation and cooling from the total track annealing temperature (>120°C) of the Cozia and Cibin massifs occurred in the Palaeocene–Early Eocene. Between the Eocene and Middle Miocene, there was a stagnation period concerning vertical displacement; the presently exposed part of the basement was buried in shallow depth. The present crests of the Cozia and Cibin Mountains were at temperatures around 80°C and 50°C, respectively. The second exhumation period occurred in Middle Miocene times. The magnitude of the Miocene vertical displacement is on the order of the present-day relief. The vertical apatite FT age distribution in the basement and the age clusters in the sedimentary rocks prove that the levels of the crests were already close to the surface in Palaeogene times. Therefore, the post-Palaeocene erosional removal from the crest zones is very limited.  相似文献   

Review of the Anisotropic Interface Ray Propagator: Symplecticity,Eigenvalues, Invariants and Applications     

Moser  T.J. 《Studia Geophysica et Geodaetica》2004,48(1):47-73

A review of the 6 × 6 anisotropic interface ray propagator matrix in Cartesian coordinates and within the framework of the Hamiltonian formalism shows that there is one unique propagator satisfying the symplectic property. This is essential, since the symplecticity furnishes an exact inverse, while an eigenvalue analysis indicates that the propagator may be arbitrarily ill-conditioned. As such, the symplectic interface propagator naturally connects to symplectic ray integration algorithms for smooth media, designed to maintain accuracy. Moreover, several ray invariants for smooth media remain invariant across interfaces. It is straightforward to derive expressions for the interface propagator, both explicit and implicit. Symplecticity is equivalent to the condition that the propagator preserves the eikonal constraint across the interface. The symplectic interface propagator complies with phase matching of the incident and reflected/transmitted ray field, and is therefore in accordance with the earlier derived 4 × 4 matrix in ray-centred coordinates. The symplectic property is related to the symmetry of the second derivative matrix of the reflected/transmitted traveltime field. Thanks to the analytic expression of the symplectic interface propagator, relating interface curvature directly to second derivatives of traveltimes observed at a datum level, numerous applications are available in the area of processing and inversion.  相似文献   

Paraxial ray methods for anisotropic inhomogeneous media   总被引：1，自引：0，他引：1  

Tijmen Jan Moser  Vlastislav &#;ervený 《Geophysical Prospecting》2007,55(1):21-37

A new formalism of surface-to-surface paraxial matrices allows a very general and flexible formulation of the paraxial ray theory, equally valid in anisotropic and isotropic inhomogeneous layered media. The formalism is based on conventional dynamic ray tracing in Cartesian coordinates along a reference ray. At any user-selected pair of points of the reference ray, a pair of surfaces may be defined. These surfaces may be arbitrarily curved and oriented, and may represent structural interfaces, data recording surfaces, or merely formal surfaces. A newly obtained factorization of the interface propagator matrix allows to transform the conventional 6 × 6 propagator matrix in Cartesian coordinates into a 6 × 6 surface-to-surface paraxial matrix. This matrix defines the transformation of paraxial ray quantities from one surface to another. The redundant non-eikonal and ray-tangent solutions of the dynamic ray-tracing system in Cartesian coordinates can be easily eliminated from the 6 × 6 surface-to-surface paraxial matrix, and it can be reduced to 4 × 4 form. Both the 6 × 6 and 4 × 4 surface-to-surface paraxial matrices satisfy useful properties, particularly the symplecticity. In their 4 × 4 reduced form, they can be used to solve important boundary-value problems of a four-parametric system of paraxial rays, connecting the two surfaces, similarly as the well-known surface-to-surface matrices in isotropic media in ray-centred coordinates. Applications of such boundary-value problems include the two-point eikonal, relative geometrical spreading, Fresnel zones, the design of migration operators, and more.  相似文献   

Impact of Spawning Substrate Complexity on Egg Survival of Atlantic Herring (<Emphasis Type="Italic">Clupea harengus</Emphasis>, L.) in the Baltic Sea     

Lena von Nordheim  Paul Kotterba  Dorothee Moll  Patrick Polte 《Estuaries and Coasts》2018,41(2):549-559

Shallow shore zones are generally considered to provide juvenile habitats for many invertebrate and fish species and additionally serve as spawning grounds for important components of oceanic food webs and fishery resources such as herring (Clupea spp.). Herring attach their demersal eggs to benthic substrates, rendering reproduction success vulnerable to environmental changes and local habitat alterations. However, little information is available on the effects of different substrates on the survival of demersal eggs. Hypothesizing that the structural complexity of spawning substrates generally affects herring egg survival and that the effect magnitude depends on the suitability of ambient environment, field experiments were conducted on a major spawning ground of C. harengus in the Southwestern Baltic Sea. Herring eggs were artificially spawned on substrates of different structural complexities and incubated in situ under differing temperature regimes, at the beginning and the end of the natural herring spawning season, to include the full suite of stressors occurring on littoral spawning beds. Results of this study indicate a positive relation between high structural complexity of spawning substrates and herring egg survival. Mean egg mortality was three times higher on substrates of lowest complexity than on highly complex substrates. These differences became even more prominent under unfavorable conditions that appeared with rising water temperatures later in the spawning season. Although the mechanisms are still unclear, we conclude that structural complexity, particularly formed by submerged aquatic vegetation, provides a crucial prerequisite for the successful reproduction of substrate spawning marine fishes such as herring in the Baltic Sea.  相似文献   

Subsurface deformation in hypervelocity cratering experiments into high‐porosity tuffs          下载免费PDF全文

Rebecca Winkler  Michael H. Poelchau  Stefan Moser  Thomas Kenkmann 《Meteoritics & planetary science》2016,51(10):1849-1870

Hypervelocity impact experiments on porous tuff targets were carried out to determine the effect of porosity on deformation mechanisms in the crater's subsurface. Blocks of Weibern Tuff with about 43% porosity were impacted by 2.5 mm and 12.0 mm diameter steel spheres with velocities between 4.8 km s^?1 and 5.6 km s^?1. The postimpact subsurface damage was quantified with computer tomography as well as with meso‐ and microscale analyses of the bisected crater subsurface. The intensity and style of deformation in mineral clasts and the tuff matrix were mapped and their decay with subsurface depth was determined. Subsurface deformation styles include pore space compaction, clast rotation, as well as microfracture formation. Evaluation of the deformation indicates near‐surface energy coupling at a calculated depth of burial of ~2 projectile diameters (d_p), which is in conflict with the crater shape, which displays a deep, central penetration tube. Subsurface damage extends to ~2 d_p beneath the crater floor in the experiments with 2.5 mm projectiles and increases to ~3 d_p for 12 mm projectiles. Based on overprinting relationships and the geometrical orientation of deformation features, a sequence of subsurface deformation events was derived (1) matrix compaction, (2) intragranular crack formation in clasts, (3) deformation band formation in the compacted matrix, (4) tensile fracturing.  相似文献