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Page 1790, results 44726 - 44750

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Analysis and modeling of long‐term stream temperatures on the Steamboat Creek Basin, Oregon: Implications for land use and fish habitat
Steven W. Hostetler
1991, Journal of the American Water Resources Association (27) 637-647
Steamboat Creek basin is an important source of timber and provides crucial spawning and rearing habitat for anadromous steelhead trout (Oncorhynchus mykiss). Because stream temperatures are near the upper limit of tolerance for the survival of juvenile steelhead, the possible long‐term effect of clear‐cut logging on...
H4IIE rat hepatoma cell bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in colonial fish-eating waterbird eggs from the Great Lakes
Donald E. Tillitt, Gerald T. Ankley, David A. Verbrugge, John P. Giesy, James P. Ludwig, Timothy J. Kubiak
1991, Archives of Environmental Contamination and Toxicology (21) 91-101
Fish-eating waterbirds from the Great Lakes of North America have shown symptoms of poisoning similar to those observed in laboratory exposures of various avian species to planar halogenated hydrocarbons (PHHs). PHHs, include among others, polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) and have...
Collimated neutron probe for soil water content measurements
J.M. Klenke, Alan L. Flint
1991, Soil Science Society of America Journal (55) 916-923
The use of uncollimated (undirected) neutron moisture meters is common in the biological and geophysical sciences. A collimated neutron probe was designed to enable measurements in specific directions from the access tube. To determine the size and shape of soil volume affecting the neutron counts, experiments were conducted to evaluate:...
Variability of an unsaturated sand unit underlying a radioactive- waste trench
Richard W. Healy, Patrick C. Miller
1991, Soil Science Society of America Journal (55) 899-907
Properties of soils vary considerably within any field. This study was conducted to investigate the variability in properties of an unsaturated sand unit that lies at a depth of 13 m below land surface. Four-hundred-forty soil core samples, obtained from a 1.75 by 18-m horizontal plane within a sand unit...
Quartz dissolution in organic-rich aqueous systems
Philip C. Bennett
1991, Geochimica et Cosmochimica Acta (55) 1781-1797
Organic electrolytes are a common component of natural waters and are known to be important in many rock-water interactions. The influence of organic electrolytes on silica mobility, quartz solubility, and quartz dissolution kinetics, however, is less well understood. While there is mounting evidence supporting the presence of an aqueous organic-silica...
Open marsh water management in the mid-Atlantic region: Aerial surveys of waterbird use
R.M. Erwin, D.K. Dawson, Daniel B. Stotts, L.S. McAllister, P.H. Geissler
1991, Wetlands (11) 209-228
Nine marsh sites were selected in Maryland, Delaware, and New Jersey to assess the importance of ponds created by Open Marsh Water Management (OMWM) to migratory birds. At eight of the nine sites, OMWM ponds were paired with areas of similar-sized natural ponds. Eleven aerial surveys were conducted,...
Seasonal variations of carbon dioxide concentrations in stony, coarse-textured desert soils of southern Nevada, USA
Christina L. Terhune, Jennifer W. Harden
1991, Soil Science (151) 417-429
Knowledge of carbon dioxide concentration in desert soils is required in theoretical models of the development of pedogenic and ground-water calcium carbonate. Most studies have concentrated on medium- to fine-textured soils in temperate to humid environments. Very little data exist for CO2 concentrations in stony, coarse-textured deposits such as those making...
Centrifugal techniques for measuring saturated hydraulic conductivity
John R. Nimmo, Karen A. Mello
1991, Water Resources Research (27) 1263-1269
Centrifugal force is an alternative to large pressure gradients for the measurement of low values of saturated hydraulic conductivity (Ksat). With a head of water above a porous medium in a centrifuge bucket, both constant-head and falling-head measurements are practical at forces up to at least 1800 times normal gravity....
Agricultural research to improve water quality
C.A. Onstad, M. R. Burkart, G.D. Bubenzer
1991, Journal of Soil and Water Conservation (46) 184-188
ime courses for ingest~on, retention and release via feces of microbial food was investigatedusing 2 b~valves w~th d~fferent feeding strategies, Potamocorbula amurensis and Macomabalthica. The results showed 2 pathways for the uptake of food material in these clams. The first isrepresented by an initlal label pulse in the feces....
Rotenone persistence in freshwater ponds: Effects of temperature and sediment adsorption
V. K. Dawson, W.H. Gingerich, R. A. Davis, P.A. Gilderhus
1991, North American Journal of Fisheries Management (11) 226-231
The persistence of rotenone was compared between a cement-lined pond (0.04 hectare) and an earthen-bottom pond (0.02 hectare) treated with 5 μL Noxfish/L (250 μg rotenone/L) during spring, summer, and fall. Water temperatures on the days of treatment in each season were 8, 22, and 15°C, respectively. Both ponds were...
Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 1. Experimental design and observed tracer movement
Denis R. LeBlanc, Stephen P. Garabedian, Kathryn M. Hess, Lynn W. Gelhar, Richard D. Quadri, Kenneth G. Stollenwerk, Warren W. Wood
1991, Water Resources Research (27) 895-910
A large-scale natural gradient tracer experiment was conducted on Cape Cod, Massachusetts, to examine the transport and dispersion of solutes in a sand and gravel aquifer. The nonreactive tracer, bromide, and the reactive tracers, lithium and molybdate, were injected as a pulse in July 1985 and monitored in three dimensions...
Sampling design for groundwater solute transport: Tests of methods and analysis of Cape Cod tracer test data
Debra S. Knopman, Clifford I. Voss, Stephen P. Garabedian
1991, Water Resources Research (27) 925-949
Tests of a one-dimensional sampling design methodology on measurements of bromide concentration collected during the natural gradient tracer test conducted by the U.S. Geological Survey on Cape Cod, Massachusetts, demonstrate its efficacy for field studies of solute transport in groundwater and the utility of one-dimensional analysis. The methodology was applied...
Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 2. Analysis of spatial moments for a nonreactive tracer
Stephen P. Garabedian, Dennis R. LeBlanc, Lynn W. Gelhar, Michael A. Celia
1991, Water Resources Research (27) 911-924
A large-scale natural gradient tracer test was conducted to examine the transport of reactive and nonreactive tracers in a sand and gravel aquifer on Cape Cod, Massachusetts. As part of this test the transport of bromide, a nonreactive tracer, was monitored for about 280 m and quantified using spatial moments....
Aquatic habitat measurement and valuation: imputing social benefits to instream flow levels
Aaron J. Douglas, Richard L. Johnson
1991, Journal of Environmental Management (32) 267-280
Instream flow conflicts have been analysed from the perspectives offered by policy oriented applied (physical) science, theories of conflict resolution and negotiation strategy, and psychological analyses of the behavior patterns of the bargaining parties. Economics also offers some useful insights in analysing conflict resolution within the context of these water...
Comment on the treatment of residual water content in “A consistent set of parametric models for the two-phase flow of immiscible fluids in the subsurface” by L. Luckner et al.
John R. Nimmo
1991, Water Resources Research (27) 661-662
Luckner et al. [1989] (hereinafter LVN) present a clear summary and generalization of popular formulations used for convenient representation of porous media fluid flow characteristics, including water content (θ) related to suction (h) and hydraulic conductivity (K) related to θ or h. One essential but problematic element in the LVN...