Coupled surface-water and ground-water model
Eric D. Swain, Eliezer J. Wexler
1991, Conference Paper
In areas with dynamic and hydraulically well connected ground-water and surface-water systems, it is desirable that stream-aquifer interaction be simulated with models of equal sophistication and accuracy. Accordingly, a new, coupled ground-water and surface-water model was developed by combining the U.S. Geological Survey models MODFLOW and BRANCH. MODFLOW is the...
Sources of dissolved and particulate organic material in Loch Vale Watershed, Rocky Mountain National Park, Colorado, USA
Jill Baron, Diane M. McKnight, A. Scott Denning
1991, Biogeochemistry (15) 89-110
The sources of both dissolved organic carbon (DOC) and particulate organic carbon (POC) to an alpine (Sky Pond) and a subalpine lake (The Loch) in Rocky Mountain National Park were explored for four years. The importance of both autochthonous and allochthonous sources of organic matter differ, not only between alpine...
Tidal mass exchange between a submersed aquatic vegetation bed and the main channel of the Potomac River
Harry L. Jenter, Nancy B. Rybicki, Robert A. Baltzer, Virginia Carter
Shane Richard M., editor(s)
1991, Conference Paper, Proceedings - National Conference on Hydraulic Engineering
Tidal mass exchange between a submersed aquatic vegetation (SAV) bed and the main channel of the Potomac River was investigated. Water levels were recorded at 5 minute intervals from August (when plants were present) through December (when plants were absent). Velocities were measured during individual tidal cycles both in the...
Tidal stirring and phytoplankton bloom dynamics in an estuary
J. E. Cloern
1991, Journal of Marine Research (49) 203-221
In South San Francisco Bay, estuarine phytoplankton biomass fluctuates at the time scale of days to weeks; much of this variability is associated with fluctuations in tidal energy. During the spring seasons of every year from 1980-1990, episodic blooms occurred in which phytoplankton biomass rose from a baseline of 2-4mg...
Terraces on the Florida escarpment: Implications for erosional processes
D.C. Twichell, C. K. Paull, L.M. Parson
1991, Geology (19) 897-900
SeaBeam bathymetric data and GLORIA (Geologic LOng-Range Inclined Asdic) sidescan sonar images of a 175-km-long section of the Florida escarpment in the eastern Guff of Mexico show that this carbonate escarpment has been eroded since its initial formation, but its morphology suggests that erosional processes have not acted uniformly on...
Mytiloides hattini n. sp.: a guide fossil for the base of the Turonian in the Western Interior of North America
W.P. Elder
1991, Journal of Paleontology (65) 234-241
Mytiloides hattini, a new species of inoceramid bivalve from the basal Turonian (Upper Cretaceous), is described and its stratigraphic importance discussed. This inoceramid is particularly significant because its first occurrence can be used as a marker for the base of the Turonian in strata that typically contain no ammonites and...
Evaluation of geographic information systems for three-dimensional ground-water modeling, Yucca Mountain, Nevada
A. Keith Turner, Elisabeth M. Ervin, Joe S. Downey
Anon, editor(s)
1991, Conference Paper, High Level Radioactive Waste Management
Fully three-dimensional representations of the geologic system at Yucca Mountain have been developed using a Geoscientific Information System, which is an expansion of a traditional Geographic Information Systems. These advanced, three dimensional, representations of Yucca Mountain are required to adequately evaluate the complex geologic and hydrologic conditions surrounding the site....
Contaminant exposure of willets feeding in agricultural drainages of the lower Rio Grande valley of south Texas
T. W. Custer, C. A. Mitchell
1991, Environmental Monitoring and Assessment (16) 189-200
Willets (Catoptrophorus semipalmatus) were collected in June and August 1986 at the outlets of two agricultural drainages into the Lower Laguna Madre of South Texas and at two other Texas coastal sites. Mean liver concentration of arsenic was higher in August than June. Over 20% of the livers had arsenic...
Shoreline deposits and diagenesis resulting from two Late Pleistocene highstands near +5 and +6 metres, Durban, South Africa
J.A.G. Cooper, R. M. Flores
1991, Marine Geology (97) 325-343
In exposures of Pleistocene rocks on the east coast of South Africa, eight sedimentary facies were distinguished on the basis of petrology, grain size, internal structures and field relationships. These are interpreted as deposits of surf zone, breaker zone, swash zone, backbeach,...
Geochemistry of lavas from Taal volcano, southwestern Luzon, Philippines: evidence for multiple magma supply systems and mantle source heterogeneity
Asta Mikijus, M.F.J. Flower, J.P.P. Huijsmans, S.B. Mukasa, P. Castillo
1991, Journal of Petrology (32) 593-627
Taal Volcano is a highly active center in the southwest Luzon volcanic field. Recent eruptions are confined to Volcano Island, a plexus of cinder cones and tuff rings surrounding a central crater, occupying (and post-dating) a massive volcano-tectonic depression resulting from multiple phases of collapse. Taal lava series can...
A lead isotopic study of the Stillwater Complex, Montana: constraints on crustal contamination and source regions
J. L. Wooden, G.K. Czamanske, M. L. Zientek
1991, Contributions to Mineralogy and Petrology (107) 80-93
Analyses of the Pb isotopic compositions of plagioclase from 23 samples covering the stratigraphic thickness of the Stillwater Complex indicate a narrow range of apparent initial isotopic compositions (206Pb/ 204Pb=13.95; 207Pb/204Pb=14.95-15.01; 208Pb/204Pb=33.6). The uniformity of our data is in contrast to, but not necessarily contradictory to, other recent investigations which...
Crustal subsidence rate off Hawaii determined from 234U/238U ages of drowned coral reefs
K.R. Ludwig, Barney J. Szabo, J.G. Moore, K. R. Simmons
1991, Geology (19) 171-174
A series of submerged coral reefs off northwestern Hawaii was formed during (largely glacial) intervals when the rate of local sea-level rise was less than the maximum upward growth rate of the reefs. Mass-spectrometric 234U/238U ages for samples from six such reefs range from 17 to 475 ka and indicate that...
40Ar/39Ar laser fusion and K-Ar ages from Lathrop Wells, Nevada, and Cima, California. The age of the latest volcanic activity in the Yucca Mountain area
Brent D. Turrin, Duane E. Champion
Anon, editor(s)
1991, Conference Paper, High Level Radioactive Waste Management
K-Ar and 40Ar/39Ar ages from the Lathrop Wells volcanic center, Nevada, and from the Cima volcanic field, California, indicate that the recently reported 20-ka age estimate for the Lathrop Wells volcanic center is incorrect. Instead an age of 119??11 to 141??10 ka is indicated for the Lathrop Wells volcanic center....
An exact solution of solute transport by one-dimensional random velocity fields
V.D. Cvetkovic, G. Dagan, A.M. Shapiro
1991, Stochastic Hydrology and Hydraulics (5) 45-54
The problem of one-dimensional transport of passive solute by a random steady velocity field is investigated. This problem is representative of solute movement in porous media, for example, in vertical flow through a horizontally stratified formation of variable porosity with a constant flux at the soil surface. Relating moments of...
Ground-water recharge from streamflow data, NW Florida
John Vecchioli, W. C. Bridges, Roger P. Rumenik, J. W. Grubbs
1991, Conference Paper
Annual base flows of streams draining Okaloosa County and adjacent areas in northwest Florida were determined through hydrograph separation and correlation techniques for purposes of evaluating variations in ground-water recharge rates. Base flows were least in the northern part of the county and greatest in the southern part. Topographic and...
Metal bioavailability and toxicity to fish in low-alkalinity lakes: A critical review
D.J. Spry, James G. Wiener
1991, Environmental Pollution (71) 243-304
Fish in low-alkalinity lakes having pH of 6·0–6·5 or less often have higher body or tissue burdens of mercury, cadmium, and lead than do fish in nearby lakes with higher pH. The greater bioaccumulation of these metals in such waters seems to result partly from the greater aqueous abundances of...
Characteristics of low-slope streams that affect O2 transfer rates
Gene W. Parker, Leslie A. DeSimone
1991, Conference Paper, Air-Water Mass Transfer
Multiple-regression techniques were used to derive the reaeration coefficients estimating equation for low sloped streams: K2 = 3.83 MBAS-0.41 SL0.20 H-0.76, where K2 is the reaeration coefficient in base e units per day; MBAS is the methylene blue active substances concentration in milligrams per liter; SL is the water-surface slope...
Buried bedrock topography, evidence of overdeepening of Winimusset Brook bedrock valley, and reinterpretation of the extent of glacial Lake Winimusset, Ware quadrangle, Massachusetts
W.W. Lapham, A. Maevsky
1991, Northeastern Geology (13) 69-73
Results from 15 test borings and 8 seismic-refraction surveys in the northeastern quarter of the Ware quadrangle, Massachusetts, provide information on the buried-bedrock topography, evidence of overdeepening of Winimusset Brook valley, information on the thickness and lithology of lacustrine deposits in glacial Lake Winimusset, and indicate a need for reinterpretation...
Geologic controls on the formation and evolution of quaternary coastal deposits of the northern Gulf of Mexico
S.J. Williams, S. Penland, A. H. Sallenger Jr., R.A. McBride, J.L. Kindlinger
1991, Conference Paper, Coastal sediments '91
A study of the barrier islands and wetlands in the deltaic plain of Louisiana is presented. Its purpose was to document rapid changes and to learn more about the processes responsible and the geologic framework within which they operate. It included systematic collection and analysis of precision nearshore hydrographic data,...
Role of sediment-trace element chemistry in water-quality monitoring and the need for standard analytical methods
Arthur J. Horowitz
1991, Conference Paper, ASTM Special Technical Publication
Multiple linear regression models calculated from readily obtainable chemical and physical parameters can explain a high percentage (70% or greater) of observed sediment trace-element variance for Cu, Zn, Pb, Cr, Ni, Co, As, Sb, Se, and Hg. Almost all the factors used in the various models fall into the category...
Magnetic susceptibility and relation to initial 87Sr/86Sr for granitoids of the central Sierra Nevada, California
P. C. Bateman, F. C. W. Dodge, R. W. Kistler
1991, Journal of Geophysical Research (96)
Measurement of the magnetic susceptibility of more than 6000 samples of granitic rock from the Mariposa 1° by 2° quadrangle, which crosses the central part of the Sierra Nevada batholith between 37° and 38°N latitude, shows that magnetic susceptibility values are above 10−2 SI units in...
The Reaction Titanite+Kyanite=Anorthite+Rutile and Titanite-Rutile Barometry in Eclogites
C.F. Manning, S.R. Bohlen
1991, Contributions to Mineralogy and Petrology (109) 1-9
Titanite and rutile are a common mineral pair in eclogites, and many equilibria involving these phases are potentially useful in estimating pressures of metamorphism. We have reversed one such reaction, {Mathematical expression} using a piston-cylinder apparatus. Titanite+kyanite is the high-pressure assemblage and our results locate the equilibrium between 15.5 15.9,...
Hatching, growth, ion accumulation, and skeletal ossification of brook trout (Salvelinus fontinalis) alevins in acidic soft waters
M.T. Steingraeber, W.H. Gingerich
1991, Canadian Journal of Zoology (69) 2266-2276
Brook trout eyed eggs and subsequent alevins were exposed to pH 5.0, 6.5, and 7.0 in soft reconstituted water and to pH 8.2 in hard well water for up to 72 d. Hatching was delayed and hatching success reduced (p < 0.05) in eyed eggs exposed to pH 5.0...
Deep crustal structure of the Precambrian basement beneath northern Lake Michigan, midcontinent North America
W.F. Cannon, Myung W. Lee, W. J. Hinze, K. J. Schulz, Alan G. Green
1991, Geology (19) 207-210
A deep seismic-reflection profile in northern Lake Michigan, midcontinent North America, provides a cross section of the crust across the 1850 Ma Penokean orogen, in which an Early Proterozoic island-arc complex was deformed between two converging Archean continental masses. The island-arc crust is...
Federal support for seismological research; past, present, and future.
D. R. Sarewitz
1991, Earthquakes & Volcanoes (USGS) (22) 115-116
Data from the past 20 years indicate a strong temporal correlation between major California earthquakes and icnreased federal funding for seismology. ...
