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Dusts in snow from the accumulation zone in the St. Elias Range appear from their chemical compositions to have come from terranes of rocks of ferromagnesian composition. These dusts, with respect to their composition and to the moderate degree of variation that occurs through a depositional year, are similar those...

A study of U(VI) adsorption by ferrihydrite was conducted over a wide range of U(VI) concentrations, pH, and at two partial pressures of carbon dioxide. A two-site (strong- and weak-affinity sites, FesOH and FewOH, respectively) surface complexation model was able to describe the experimental data well over a wide range...

Riparian forests are important for maintaining vertebrate species richness in the southwestern United States, but they have become restricted in distribution due to both historical and current management practices. In order to counteract continued loss of this habitat, several mitigation programs were developed in the middle Rio Grande Valley of...

A preliminary assessment was made in 1992 of chlorinated organic compounds in sediments and in livers of striped bass from the San Francisco Bay-Delta Estuary. Samples of sediment and striped bass livers contained DDT (ethane, 1,1,1-trichloro-2,2-bis (p-chlorophenyl)-) and its degradation products, DDD (ethane, 1,1-dichloro-2,2-bis(p-chlorophenyl)-) and DDE (ethylene, 1,1-dichloro-2,2-bis (p-chlorophenyl)-); PCBs...

This paper presents results of chemical speciation and reaction path calculations that model fluid chemistry evolution and ore deposition in the main-stage Creede, Colorado, epithermal system. An extensive geologic, mineralogic, and geochemical framework for mineralization has been developed by many researchers for the central and southern district vein systems (OH...

The relative role of block versus continuum deformation of continental lithosphere is a current subject of debate. Continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies. In contrast, block...

LABORATORY results demonstrating that basic to ultrabasic melts become denser than olivine-rich mantle at pressures above 6 GPa (refs 1-3) have important implications for basalt petrogenesis, mantle differentiation and the storage of volatiles deep in the Earth. A density cross-over between melt and solid in the extensively molten Archaean mantle...

Water resources data for the 1999 water year in Florida consist of continuous or daily discharges for 354 streams, periodic discharge for 17 streams, continuous or daily stage for 121 streams, periodic stage for 1 stream, peak stage and discharge for 38 streams, continuous or daily elevations for 21 lakes,...

Fish were sampled at the Ed Weed State Fish Hatchery (South Hero, Vermont, USA) in September 1992. Aeromonas salmonicida was common, with concentrations as high as 105 to 107 colony-forming units per gram of mucus, and readily recovered from most mucus samples obtained from furunculosis-sensitive populations of...

The configuration of the southward-sloping water table under Yucca Mountain is dominated by an abrupt decline of 300 m over a distance of less than 2 km. This northeast-striking zone of large...

Aeromonas salmonicida was isolated from paddlefish (Polyodon spathula) mortalities collected during an epizootic of furunculosis at the Spring River State Hatchery, Arkansas (USA), in 1992. Isolates of the bacterium were obtained from culture of gill and kidney tissue. This is the first epizootic of bacterial etiology to be reported in paddlefish....

Measurements of currents and light transmission were made at bottom tripods and moorings arrayed across the northern California continental shelf along the Coastal Ocean Dynamics Experiment (CODE) "C" transect as part of the 1990-1991 Sediment Transport Events on Shelves and Slopes (STRESS) experiment. In combination with meteorological and wave data...

Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and...

Hybridization has been used in aquaculture to produce fish that exhibit improved growth and survival over parent species. Previous studies produced an intergeneric hybrid by crossing female black drum Pogonias cromis with male red drum Sciaenops ocellatus. In the present study, the two parent species and their hybrid were simultaneously cultured in ponds...

The paper “Hydrates Offshore Brazil” by Rogerio L. Fontana and Alexandre Mussumeci presents some important information that strongly indicates the presence of gas hydrates on the southern Brazilian continental margin. However, the acoustic compressional wave velocity structure reported for the Brazilian margin sediments is highly unusual and quite puzzling. We...

Phenocrysts in porphyritic volcanic rocks may originate in a variety of ways in addition to nucleation and growth in the matrix in which they are found. Porphyritic rhyodacite lavas that underlie the eastern half of Mount Mazama, the High Cascade andesite/dacite volcano that contains Crater Lake caldera, contain evidence that...

[No abstract available]...

The Galapagos Fossil Hydrothermal Field is composed of altered oceanic crust and extinct hydrothermal vents within the eastern Galapagos Rift between 85°49′W and 85°55′W. The discharge zone of the hydrothermal system is revealed along scarps, thus providing an opportunity to examine the uppermost mineralized, and highly altered interior parts of...

Flooding of the Iowa River during July and August 1993 caused extensive contraction scour at the State Highway 99 bridge over the Iowa River at Wapello, Iowa. At least 3.3 m of piling under the footing of the second pier from the right (west) abutment were exposed. The scoured streambed...

Senaite, Pb(Ti,Fe,Mn)21O38, a member of the crichtonite group, was first described from alluvial gravels near Dattas, Minas Gerais, Brazil. It was subsequently reported (always from alluvial stream gravels) from about seven additional localities. "Senaite' from the first in situ source in Brazil, at the Fazenda Guariba, Minas Gerais, Brazil was...

Natural samples of magnetite and ilmenite were experimentally weathered in pH 1–7 anoxic solutions at temperatures of 2–65 °C. Reaction of magnetite is described as [Fe2+Fe23+]O4(magnetite) + 2H+ → γ[Fe23+]O3(maghemite) + Fe2+ + H2O. Dynamic polarization experiments using magnetite electrodes confirmed that this reaction is controlled by two electrochemical half cells, 3[Fe2+Fe23+]O4(magnetite) → 4γ[Fe23+]O3(maghemite) + Fe2+ + 2e− and [Fe2+Fe23+]O4(magnetite) +...

The results from two different types of gas measurement, telemetered in situ monitoring of reducing gases on the dome and airborne measurements of sulfur dioxide emission rates in the plume by correlation spectrometry, suggest that the combination of these two methods is particularly effective in detecting periods of enhanced degassing...

The Ren gold prospect, Elko County, Nevada, is in the northern part of the Carlin trend, two kilometers northwest of the recently-discovered, high-grade Purple Vein deposit. The Ren area is underlain mainly by Paleozoic sedimentary rocks, consisting of limestone, calcareous siltstone, and mudstone of the eastern (carbonate) assemblage, overlain in...