Gravel transport,gravel harvesting,and channel-bed degradation in rivers draining the southern olympic mountains,Washington, U.S.A.

The potential for gravel extraction to adversely affect anadromous fish habitat in three gravel-bed rivers of southwestern Washington, U.S.A., prompted the need to determine sustainable rates of gravel removal. This was accomplished by evaluating the components of a long-term sediment mass balance for the three rivers. Average annual gravel transport was determined by three independent methods. The closely agreeing results indicate that annual bedload supply decreases downstream through deposition and storage in response to declining gradient and from attrition during transport, as confirmed by laboratory experiments. A survey of gravel-bar harvesting operations indicates that the annual replenishment rate has been exceeded for up to three decades, often by more than tenfold. Analysis of data from nine stream gauging stations over a 55-yr period indicates degradation of about 0.03 m/yr in these reaches and suggests that bed degradation has produced the difference between the replenishment rates and the volumes of gravel harvested from the river beds and bars.     

Resource partitioning and regional development strategies in the Ecuadorian Amazon

This paper argues that the process of establishing claims and control over resources, referred to as resource partitioning, structures frontier societies in ways which impede subsequent efforts at rural development. Conflicts over claims to resources create divisions among local elites which prevent the formation of coalitions to promote development. Struggles for control over the flow of resources out of a region cause regional development agencies to pursue transportation policies which retard development by isolating the region from all but one commercial center. A case study of resource partitioning and rural development efforts in the Ecuadorian Amazon illustrates the argument.     

Limitations of Monitoring Wells for the Detection and Quantification of Petroleum Products in Soils and Aquifers

Theoretical analysis and laboratory column experiments were carried out to investigate the conditions required for petroleum products (oil) to flow into a well installed through a sandy porous medium contaminated with the oil. The results indicated that oil would flow into a well only after a layer of "free oil" is formed in the adjacent porous medium. Because significant quantities of oil could be stored in the porous medium under the influence of capillary suction prior to the formation of the zone of free oil, the presence of oil in a well would indicate an advanced stage of oil contamination of the subsurface. While monitoring wells could be used to delineate the extent of the free-oil plume and the plume of dissolved petroleum constituents, they are not useful for delineating the extent of capillary held oil.
The experimental results also indicated that the ratio of the oil-layer thickness in the well to that in the porous medium is not a constant as is sometimes assumed in practice. Further, estimates of the oil thickness in the medium based on the oil thickness in wells and on capillary properties measured in the laboratory were sensitive to the values of the parameters used in these estimates. The measured thickness of the oil layer in a monitoring well alone may not yield reliable estimates of the amount of oil in the subsurface, and assuming that the oil-thickness ratio is a constant can lead to inadequate site assessments and inappropriate remedial plans.     

The surface of labradorite feldspar after acid hydrolysis

After reaction with a pH < 4, the surface of labradorite is extensively enriched in Si and H, and depleted in Al, Ca and Na relative to an unreacted crystal. However, the amount of hydrogen measured in the reacted surface is less than that predicted on the basis of exchange of hydrogen (or hydronium) ions for cations in the feldspar. By analogy with studies of silicate glass, this low concentration of hydrogen suggests that some silanol groups in the reacted surface repolymerize subsequent to ion-exchange and depolymerization reactions. The net result is a relatively porous, Si-rich leached layer which is amorphous to electron diffraction, and which allows rapid diffusion of unreactive solutes.

Both the surface area of the reacted feldspar and the porosity increase with acid hydrolysis. Modeling of nitrogen sorption onto the surface suggests that the pores have a nominal radius of 20–80 Å or less. This distribution of pore sizes resembles other acid-reacted silicate materials, such as glass, chrysotile and kaolinite. Although the mineral surface clearly becomes more porous during acid hydrolysis, the increase in powder area also does not coincide with an increase in the flux of dissolved Si from the powder. We thus attribute most of this increase in area to spallation of the silica-rich surface from the feldspar upon drying.     

Experimental investigation of turbulent processes in a complex terrain

In the present paper the first results of the international KOPEX-86 experiment are presented. The experiment took place at the Kopisty Atmospheric Observatory of the Institute of Physics of the Atmosphere in Prague as part of a special project of the Commission of the Academy of Sciences in Planetary Geophysics (KAPG) in June and July 1986. Using 4 ultrasonic anemometers at 4 levels up to 80 m, Doppler-SODAR and wind-, temperature- and radiation balance gradients from 2 to 80 m, a complex investigation of the atmospheric boundary layer in an industrial area was made. The authors present the first results of

The Sensitivity of Four Monitoring Well Sampling Systems to Low Concentrations of Three Volatile Organics

Four state-of-the-art ground water sampling systems were analyzed to determine their reliability in providing representative samples of the volatile chlorinated hydrocarbons trichloroethylene (TCE), perchloroethylene (PCE), and 1,1,1-trichloroethane (TCA) from a simulated monitoring well. The sampling systems studied represent four commonly used devices, including a stainless steel and Teflon® piston pump, a Teflon bailer, a Teflon bladder pump, and a PVC air-lift pump.
Controlled laboratory sampling experiments were conducted in a tank and well test chamber designed to approximate field conditions. A well purging and sampling procedure was used in the test apparatus to determine the accuracy and precision of each device for detecting low concentrations of the compounds in ground water. The compounds selected are some of the most ubiquitous hazardous contaminants found in shallow aquifers near hazardous waste sites throughout the United States.
No significant statistical difference was found among the four sampling systems in detecting the compounds.     

Infrared spectroscopic investigation of hydroxyl in β-(Mg,Fe)2SiO4 and coexisting olivine: Implications for mantle evolution and dynamics

Wadsleyite (β-(Mg,Fe)₂SiO₄) is a major constituent of the Earth's transition zone and is known to accommodate OH. The portion of the transition zone between 400–550 km could be an important source or sink for hydroxyl in plumes and slabs intersecting this region. Micro-infrared spectroscopy has been carried out on the β-phase and coexisting metastable olivine synthesized in a multianvil apparatus at 14 GPa and 1550–1650 K under hydrous conditions. Single-crystal and polycrystal specimens of both phases were analyzed in the 1800–8500 cm^?1 frequency region to determine the speciation, abundances, and partitioning behavior of the hydrous components in coexisting β-phase and olivine. β-phase spectra consistently show three distinct OH bands at 3329, 3580, and 3615 cm^?1. OH concentrations range from 10000–65000 H/10⁶ Si. A strong positive correlation of grain size and extent of transformation with OH concentration in the β-phase indicates that grain-growth and transformation rates are enhanced in a hydrous environment. Olivine spectra are variable, but consistently show a prominent broad-band absorbance representing molecular H₂O, consistent with the infrared signature of the starting material. OH concentrations in olivine range from <300–1400 H/10⁶ Si. The highest OH concentrations measured for olivine and the β-phase may represent solubility limits, in which case the OH solubility ratio between these two phases is approximately 1∶40. Where both phases coexist and are undersaturated with OH, the partitioning ratio of OH between them is about 1∶100. The large solubility contrast between olivine and the β-phase suggests a mechanism for hydrating the transition zone via olivine carried down in subducting slabs. Plumes impinging on an OH-rich upper transition region could cause H₂ or H₂O to be released upon transformation of the β-phase to olivine, resulting in initiation of secondary upwellings. If dissolution of OH weakens the β-phase, and if OH is present in the mantle, the region between 400–550 km could be a zone of low viscosity.     

Petrology of fibrous coal (fusain) and associated inertinites from the Early Paleocene of the central Alberta Plains

Megascopic, micropetrographic and scanning-electron microscopic investigations of fibrous coal indicate that paleo-wildfires were common occurrences in the mire which produced Highvale coals. At least 20 fibrous coal (fusain) horizons have been identified in corehole samples from the pit no. 3 locality at Highvale, in the central Alberta Plains. Thicknesses of individual horizons vary, and are not particular to any stratigraphic position within coal seams. The majority of these fibrous horizons is within the two thick economic seams, the Highvale Nos. 1 and 2, which are characteristically megascopically dull. The dullness of given lithotypes is largely related to inertinite content with fibrous coal containing 51% inertinite on average, and selected horizons comprised of as much as 85% inertinite. Semifusinite and inertodetrinite are the predominant inertinites, with a few horizons exhibiting highly reflecting fusinite. Macrinite is rare, and micrinite is absent. SEM investigations reveal that certain fibrous coals exhibit excellent preservation of the original gymnospermous (Taxodium) woody tissue. Features such as homogenization and swelling of the cell walls, elimination of the middle lamellae, and preservation of bordered pits are clearly indicative of charcoal formation as a product of paleo-wildfires. Depending upon the nature of the fire, temperatures obtained and the nature of the mire vegetation, a wide range of inertinite precursors can be produced.     

Late Pleistocene Vertebrates and Other Fossils from Epiguruk, Northwestern Alaska

Sediments exposed at Epiguruk, a large cutbank on the Kobuk River about 170 km inland from Kotzebue Sound, record multiple episodes of glacial-age alluviation followed by interstadial downcutting and formation of paleosols. Vertebrate remains from Epiguruk include mammoth, bison, caribou, an equid, a canid, arctic ground squirrel, lemmings, and voles. Radiocarbon ages of bone validated by concordant ages of peat and wood span the interval between about 37,000 and 14,000 yr B.P. The late Pleistocene pollen record is dominated by Cyperaceae, with Artemisia, Salix, Betula, and Gramineae also generally abundant. The fossil record from Epiguruk indicates that the Kobuk River valley supported tundra vegetation with abundant riparian willows during middle and late Wisconsin time. Large herbivores were present during the height of late Wisconsin glaciation as well as during its waning stage and the preceding interstadial interval. The Kobuk River valley would have been a favorable refugium for plants, animals, and possibly humans throughout the last glaciation.