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Environmental problems are difficult to solve because their causes and effects are not easily understood. When attempts are made to analyze causes and effects, the principal challenge is organization of information into a framework that is logical, technically defensible, and easy to understand and communicate. When decisionmakers attempt...

The Devonian plant fossil Protosalvinia (Foerstia) has been examined by solid-state 13C nuclear magnetic resonance spectroscopy (NMR) and pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). Results of these studies reveal that the chemical structure of Protosalvinia is remarkably similar to that of coalified wood. A well-defined phenolic carbon peak in the NMR spectra and the appearance of phenol...

Midplate seismicity associated with some former rift-zones is distributed diffusely near, but exterior to, the rift basins. This “basin-exterior” seismicity cannot be attributed to reactivation of major basin-border faults on which upper-crustal extension was concentrated at the time of rifting, because the border faults dip beneath the basins. The seismicity...

Seismic-reflection profiles across part of the New Madrid seismic zone in northeastern Arkansas and southeastern Missouri show a faulted and structurally complex zone, originally known as Charlie’s ridge but herein renamed Blytheville arch, which is about 10 to 15 km wide and about 110 km long. Several exploratory drill holes...

The largest historical earthquake in South Carolina, and in the southeastern US, occurred in the Coastal Plain province, probably northwest of Charleston, in 1886. Locations for aftershocks associated with this earthquake, estimated using intensities based on newspaper accounts, defined a northwest trending zone about 250 km long that was at...

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This profile, part of a series of profiles concerning coastal habitats of the United States, is a detailed examination of the soft-bottom benthos of San Francisco Bay. A U.S. Fish and Wildlife Service and California Department of Fish and Game report (1979) entitled "Protection and Restoration of San Francisco Bay...

The Rallidae are a diverse group in their habitat selection, yet most North American species occur in or near wetlands As a consequence, most species are subject to habitat enhancement or perturbation from waterfowl management programs. The overall effects of these management programs relative to rallid conservation have...

The toxicity of selenomethionine and sodium selenite to mallard ducklings (Anas platyrhynchos) was measured by feeding each form from hatching to six weeks of age at dietary concentrations of 0, 10, 20, 40, and 80 ppm selenium. At 80 ppm selenium, sodium selenite caused 97.5% mortality by six weeks and...

Whole-body samples of bluegills (Lepomis macrochirus) and common carp (Cyprinus carpio) from the San Joaquin River and two tributaries (Merced River and Salt Slough) were analyzed to determine if the concentrations of any of nine elements were elevated as a result of exposure of the fish to agricultural subsurface (tile)...

The hydraulic potentiomanometer described herein consists of a potentiometer connected to a manometer by a flexible tube. The device is used to directly measure the direction of seepage as well as the hydraulic-head difference between groundwater and surface water. The device works most effectively in sandy materials. For accurate measurements...

Ferromanganese oxide crusts, which accumulate on unsedimented surfaces in the open ocean1–6, derive most of their metal content from dissolved and particulate matter in ambient bottom water7,8, in proportions modified by the variable scavenging efficiency of the oxide phase for susceptible ions9. They differ in this respect from abyssal nodules,...

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Jumbo multiple plate samplers were suspended in a river at 0.3 and 1 m depth in one of three orientations: interplate spaces closed to downwelling light and open to flow, open to light and flow, or open to light and closed to flow. Mean numbers of colonizing taxa and individuals...

A simulation study was undertaken to assess the sampling stability of the variable loadings in linear discriminant function analysis. A factorial design was used for the factors of multivariate dimensionality, dispersion structure, configuration of group means, and sample size. A total of 32 400 discriminant analyses were conducted, based on...

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Tissue was obtained from 59 manatee (Trichechus manatus) carcasses salvaged from 20 counties in Florida. Allozyme phenotypes at 24 structural loci were determined by gel electrophoresis. Averages for the proportion of polymorphic loci and mean heterozygosity were 0.300 (range, 0.167-0.417) and 0.050 (range, 0.028-0.063), respectively. These estimates are equivalent to...

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We investigated the effects of both asymmetries and differing food levels on contest outcomes of wintering Bald Eagles (Haliaeetus leucocephalus) feeding on chum salmon (Oncorhynchus keta) carcasses. Large eagles, regardless of age, were more successful in pirating than smaller eagles. Small pirating eagles were usually unsuccessful unless they were adults...

The fossorial rodent Geomys bursarius excavates tunnels to find and gain access to belowground plant parts. This is a study of how the foraging path of this animal, as denoted by feeding-tunnel systems constructed within experimental gardens, reflects both adaptive behavior and constraints associated with the fossorial lifestyle. The principal...

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Longitudinal advective solute movement in heterogeneous porous media is investigated by considering the solute arrival time at a plane perpendicular to the mean fluid velocity. The moments of the solute arrival time are defined in terms of the stochastic properties of a statistically anisotropic hydraulic conductivity field. The flux‐averaged concentration...