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A stochastic model of mallard (Anas platyrhynchos) productivity has been developed over a 10-year period and successfully applied to several management questions. Here we review the model and describe some recent uses and improvements that increase its realism and applicability, including naturally occurring changes in wetland habitat, catastrophic weather events,...

The origin of three Red Sea submarine brine pools was investigated by analysis of the S and O isotope ratios of dissolved sulfate and Sr isotope ratios of dissolved Sr in the brines. Sulfur and O isotope ratios of sulfate and Sr isotope ratios of evaporitic source rocks for the...

A recently developed instrumentation system has been used to monitor simultaneously flow conditions and suspended sediment distribution in the bottom boundary layer of a tidal channel within San Francisco Bay, California. Measurements were made every 15 min over six successive flood and ebb tidal cycles. They included mean velocity profiles...

Apparent apatite fission-track ages from drill core penetrating basement on the flank of the Transcontinental Arch in northwestern Iowa range from 934 ± 86 to 641 ± 90 Ma. These ages, the oldest reported in North America, record at least two...

An extensive survey was conducted in fall 1978 to determine the distribution and abundance of submersed macrophytes through the St. Clair-Detroit River system from Lake Huron to Lake Erie. Submersed macrophytes, representing 19 taxa, were widely distributed in the system, being found on 358 km2 (30%) of the total 1185 km2 of...

Adult forms of the cladoceran Bythotrephes cederstroemi Schoedler (Cercopagidae), a widespread European freshwater zooplankter, occurred in the stomachs of four common species of Lake Erie fish (yellow perch, Perca flavescens; white perch, Morone americana; white bass, M. chrysops; and walleye, Stizostedion vitreum vitreum) collected in early October 1985. The fish were collected at several stations in...

Lake trout were collected in graded-mesh gill nets and forage fishes were collected in trawls in mid December 1981 and late March 1982. The length ranges of 317 lake trout caught in December and 138 in March were 280–767 and 286–857...

The precipitous decline in abundance of walleyes (Stizostedion vitreum vitreum) in western Lake Erie during the 1960s caused major concerns for the future of this resource. Mercury contamination in walleyes in 1970 resulted in a moratorium on commercial fishing in United States and Canadian waters. The opportunity arose for resource...

The number of cliff swallow (Petrochelidon pyrrhonata) nests at a farmstead in southeastern North Dakota increased at an average annual rate of 87% with house sparrow (Passer domesticus) removal during 1957-60 and 1970-72. Harassment of nesting cliff swallows by house sparrows, adult swallow mortality from cold weather in late May,...

No abstract available....

Temperature surveys at depths of 1–2 m have had varying success in geothermal exploration in the Basin and Range province. The most successful surveys have identified patterns of near-surface thermal-fluid flow within areas of less than 2 km2. Results have been less consistent in larger areas where zones of hydrothermal...

Numerical modeling techniques are used to examine the hydrogeologic, design, and management factors governing the recovery efficiency of subsurface fresh-water storage. The modeling approach permitted many combinations of conditions to be studied. A sensitivity analysis was used that consisted of varying certain parameters while keeping constant as many other parameters...

A microcomputer coupled to a video digitizer was used to develop methods for measuring areas of tree rings and for delineating and measuring microscopic anatomical features. Digitally imaged areas of individual rings of a loblolly pine cross section were within 2.6% of areas measured with a planimeter and were more...

Water budget and isotopic analyses of water in the eastern Snake River Plain aquifer system confirm that most, if not all, of the water is local meteoric in origin. Solute mass-balance arguments suggest that ∼5 × 109 moles of calcite and 2.6 × 109 moles of silica are precipitated annually...

Changes in salinity and nitrate concentration in groundwater and surface water in the semiarid Arkansas River valley of southeastern Colorado, USA were related primarily to irrigation practices. Water is applied to fields by flood irrigation through ditches and furrows. Irrigation water is derived in nearly equal amounts from surface water...

This paper presents results of site-response experiments performed five months after the M//s equals 7. 8 Central Chile Earthquake of 3 March 1985. The objectives of the experiments performed are to identify amplification due to topography and geology. Topographical amplification at Canal Beagle, a subdivision of Vina del Mar, was...

As part of the Gulf Coast Regional Aquifer System Analysis (GC RASA) study, data from 184 geophysical well logs were used to define the geohydrologic framework of the Mississippi embayment aquifer system in Mississippi for flow model simulation. Five major aquifers of Eocene and Paleocene age were defined within this...

Systematic modes of spatial and temporal variation in a 13-y record of stream sulfate from a nationwide network of headwater sampling stations are defined using principal components. Based on the undisturbed nature of the sampling network, it is suggested that these modes of stream sulfate variability are analogues for variations...

The effects of acid deposition on surface waters in eastern United States watersheds having similar size, physiography, climate and land use are related to the composition of the underlying bedrock. Watersheds developed on greenstone, calcareous shale, sandstone, granite, and schist differ in their ability to neutralize acid deposition....

Certain geologic media are known to have small permeability; subsurface environments composed of these media and lacking well developed secondary permeability have groundwater flow sytems with many distinctive characteristics. Moreover, groundwater flow in these environments appears to influence the evolution of certain hydrologic, geologic, and geochemical systems, may affect the...

Carbon and sulfur abundance and δ34S of pyrite sulfur were studied in cores of selected Cretaceous marine shales from the western interior of North America. Sulfur/carbon ratios average 0.67, a value greater than that observed in recent marine sediments and much higher than...

Many techniques are available for reducing landslide hazards; 27 are described in this paper. Prerequisites for the successful use of these techniques are hazard information understandable to nongeologists and adequate communication of this information to those who will, or are required to, use it. It is concluded that certain factors...

MAPGEN is a software system that facilitates production of cartographic displays in the research and production environment. The system generates a set of metagraphic overlays of application-defined geographical information that can be aggregated in any combination for display without reprocessing the original data. An overview of the control files, available...

Thalenite occurs as a minor constituent of a single small pegmatite within an extensive area of granite a few miles S of Kingman, Arizona. Partly crystalline and partly metamict, this thalenite has composition Y3(Si3O10)(OH), with extensive substitution of Y by REE, especially Dy, Er and Yb. Upon heating, even at...

The understanding of quantum mechanical phenomena has come to rely heavily on theory framed in terms of operators and their eigenvalue equations. This paper investigates the utility of that technique as related to the reciprocity principle in diffuse reflection. The reciprocity operator is shown to be unitary and Hermitian; hence,...