Lunar prospector epithermal neutrons from impact craters and landing sites: Implications for surface maturity and hydrogen distribution
J. R. Johnson, W. C. Feldman, D. J. Lawrence, S. Maurice, T. D. Swindle, P. G. Lucey
2002, Journal of Geophysical Research E: Planets (107) 3-1-3-8
Initial studies of neutron spectrometer data returned by Lunar Prospector concentrated on the discovery of enhanced hydrogen abundances near both lunar poles. However, the nonpolar data exhibit intriguing patterns that appear spatially correlated with surface features such as young impact craters (e.g., Tycho). Such immature crater materials may have...
A comparison of factors controlling sedimentation rates and wetland loss in fluvial-deltaic systems, Texas Gulf coast
W.A. White, R.A. Morton, C. W. Holmes
2002, Geomorphology (44) 47-66
Submergence of coastal marshes in areas where rates of relative sea-level rise exceed rates of marsh sedimentation, or vertical accretion, is a global problem that requires detailed examination of the principal processes that establish, maintain, and degrade these biologically productive environments. Using a simple 210Pb-dating model, we measured sedimentation rates...
Pathways of nutrient loading and impacts on plant diversity in a New York peatland
Judith Z. Drexler, B. L. Bedford
2002, Wetlands (22) 263-281
Nutrient loading is a subtle, yet serious threat to the preservation of high diversity wetlands such as peatlands. Pathways of nutrient loading and impacts on plant diversity in a small peatland in New York State, USA were determined by collecting and analyzing a suite of hydrogeological, hydro-chemical, soil, and vegetation...
Natural attenuation of chlorinated solvents at Area 6, Dover Air Force Base: Groundwater biogeochemistry
M.E. Witt, G.M. Klecka, E.J. Lutz, T.A. Ei, N.R. Grosso, F. H. Chapelle
2002, Journal of Contaminant Hydrology (57) 61-80
Monitored natural attenuation (MNA) has recently emerged as a viable groundwater remediation technology in the United States. Area 6 at Dover Air Force Base (Dover, DE) was chosen as a test site to examine the potential for MNA of tetrachloroethene (PCE) and trichloroethene (TCE) in groundwater and aquifer sediments. A...
Recovery of severely compacted soils in the Mojave Desert, California, USA
R. H. Webb
2002, Arid Land Research and Management (16) 291-305
Often as a result of large-scale military maneuvers in the past, many soils in the Mojave Desert are highly vulnerable to soil compaction, particularly when wet. Previous studies indicate that natural recovery of severely compacted desert soils is extremely slow, and some researchers have suggested that subsurface compaction may not...
Detection, quantitation and identification of enteroviruses from surface waters and sponge tissue from the Florida Keys using real-time RT-PCR
K.A. Donaldson, Dale W. Griffin, J.H. Paul
2002, Water Research (36) 2505-2514
A method was developed for the quantitative detection of pathogenic human enteroviruses from surface waters in the Florida Keys using Taqman (R) one-step Reverse transcription (RT)-PCR with the Model 7700 ABI Prism (R) Sequence Detection System. Viruses were directly extracted from unconcentrated grab samples of seawater, from seawater concentrated by...
Dust coatings on basaltic rocks and implications for thermal infrared spectroscopy of Mars
J. R. Johnson, P. R. Christensen, P. G. Lucey
2002, Journal of Geophysical Research E: Planets (107) 2-1-2-19
Thin coatings of atmospherically deposited dust can mask the spectral characteristics of underlying surfaces on Mars from the visible to thermal infrared wavelengths, making identification of substrate and coating mineralogy difficult from lander and orbiter spectrometer data. To study the spectral effects of dust coatings, we acquired thermal emission and...
Partial entrainment of gravel bars during floods
Christopher P. Konrad, Derek B. Booth, Stephen J. Burges, David R. Montgomery
2002, Water Resources Research (38) 9-1-9-16
Spatial patterns of bed material entrainment by floods were documented at seven gravel bars using arrays of metal washers (bed tags) placed in the streambed. The observed patterns were used to test a general stochastic model that bed material entrainment is a spatially independent, random process where the probability of...
System analysis to estimate subsurface flow: From global level to the State of Minnesota
B.A. Shmagin, R. Kanivetsky
2002, Environmental Geology (42) 259-269
Stream runoff data globally and in the state of Minnesota were used to estimate subsurface water flow. This system approach is based, in principal, on unity of groundwater and surface water systems, and it is in stark contrast to the traditional deterministic approach based on modeling. In coordination with methodology...
Otters
James A. Estes, James L. Bodkin
William F. Perrin, Bernd Wursing, J.G.M. Thewissen, editor(s)
2002, Book chapter, Encyclopedia of marine mammals
The otters (Mustelidae; Lutrinae) provide a unique look into the evolution of marine living by mammals. This is because most extant marine mammals have been so highly modified by long periods of selection for life in the sea that they bare little resemblance to their terrestrial ancestors. Marine otters, by...
Suspended sediment transport on the continental shelf near Davenport, California
J. P. Xu, M. Noble, S.L. Eittreim
2002, Marine Geology (181) 171-193
Suspended sediment transport on the shelves off Santa Cruz and Davenport, California is studied using field measurements and bottom boundary layer modeling. Strong transport events mostly occur during storms in winter; the volume of winter sediment transport is at least one order of magnitude greater than that of summer/spring transport....
Variations in sediment texture on the northern Monterey Bay National Marine Sanctuary continental shelf
B. D. Edwards
2002, Marine Geology (181) 83-100
The storm-protected continental shelf of Monterey Bay, part of the Monterey Bay National Marine Sanctuary, north-central California, is subject to abundant, episodic sediment input from fluvial sources. North of Monterey Bay, conditions of reduced sediment supply combined with the exposed nature of the shelf provide an effective laboratory for studying...
Accumulation rate and mixing of shelf sediments in the Monterey Bay National Marine Sanctuary
R.C. Lewis, K.H. Coale, B. D. Edwards, M. Marot, J.N. Douglas, E.J. Burton
2002, Marine Geology (181) 157-169
The distribution of excess 210Pb in 31 sediment cores was used to determine modern (last 100 yr) mass accumulation rates and the depth of sediment mixing on the continental shelf between Pacifica and Monterey, California, USA. Apparent mass accumulation rates average 0.27 g cm-2 yr-1 and range from 0.42 g...
On geological interpretations of crystal size distributions: Constant vs. proportionate growth
D. D. Eberl, D. E. Kile, V. A. Drits
2002, American Mineralogist (87) 1235-1241
Geological interpretations of crystal size distributions (CSDs) depend on understanding the crystal growth laws that generated the distributions. Most descriptions of crystal growth, including a population-balance modeling equation that is widely used in petrology, assume that crystal growth rates at any particular time are identical for all crystals, and, therefore,...
Large-scale fractures related to inception of the Yellowstone hotspot
J.M.G. Glen, D. A. Ponce
2002, Geology (30) 647-650
During middle Miocene time, western North America was subject to flood-basalt volcanism, dike-swarm injection, and broad-scale fracturing and folding of the crust. We propose a simple model to account for these events and for a regional pattern of geologic and geophysical features. Aeromagnetic maps reveal some of the most important...
Historical and modern distributions of benthic foraminifers on the continental shelf of Monterey Bay, California
M. McGann
2002, Marine Geology (181) 115-156
Historical (early 1930s) and modern samples provide a detailed account of the spatial distribution of benthic foraminifers on the continental shelf of Monterey Bay, California. Ten species among a total of 110 present dominated the 110 samples investigated in the historical study. A cluster analysis of the foraminiferal abundances in...
Accelerated solvent extraction followed by on-line solid-phase extraction coupled to ion trap LC/MS/MS for analysis of benzalkonium chlorides in sediment samples
I. Ferrer, E. T. Furlong
2002, Analytical Chemistry (74) 1275-1280
Benzalkonium chlorides (BACs) were successfully extracted from sediment samples using a new methodology based on accelerated solvent extraction (ASE) followed by an on-line cleanup step. The BACs were detected by liquid chromatography/ion trap mass spectrometry (LC/MS) or tandem mass spectrometry (MS/MS) using an electrospray interface operated in the positive ion...
Operating the EOSDIS at the land processes DAAC managing expectations, requirements, and performance across agencies, missions, instruments, systems, and user communities
T. A. Kalvelage
Barnes W.L., editor(s)
2002, Conference Paper
NASA developed the Earth Observing System (EOS) during the 1990'S. At the Land Processes Distributed Active Archive Center (LP DAAC), located at the USGS EROS Data Center, the EOS Data and Information System (EOSDIS) is required to support heritage missions as well as Landsat 7, Terra, and Aqua. The original...
Relationship of gas hydrate concentration to porosity and reflection amplitude in a research well, Mackenzie Delta, Canada
Y.K. Jin, Myung W. Lee, T. S. Collett
2002, Marine and Petroleum Geology (19) 407-415
Well logs acquired at the Mallik 2L-38 gas hydrate research well. Mackenzie Delta, Canada, reveal a distinct trend showing that the resistivity of gas-hydrate-bearing sediments increases with increases in density porosities. This trend, opposite to the general trend of decrease in resistivity with porosity, implies that gas hydrates are more...
Key Largo Limestone revisited: Pleistocene shelf-edge facies, Florida Keys, USA
Multer H. Gray, E. Gischler, J. Lundberg, K. R. Simmons, E.A. Shinn
2002, Facies 229-272
New dates and analysis of 12 deep and 57 shallow cores allow a more detailed interpretation of the Pleistocene shelf edge of the Florida Platform as found in various facies of the Key Largo Limestone beneath the Florida Keys. In this study a three-phase evolution of the Quaternary units (Q1-Q5)...
Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects
S.A. Adlerstein, A. Temming, N. Mergardt
2002, ICES Journal of Marine Science (59) 497-515
This study analyses data from over 20 000 haddock stomachs collected during the 1981 and 1991 Stomach Sampling Projects of the North Sea. Sampling was within the framework of the Multispecies Virtual Population Analysis (MSVPA) for fisheries stock assessment. In 1981 stomachs were collected to calculate input feeding parameters from...
Porometric properties of siliciclastic marine sand: A comparison of traditional laboratory measurements with image analysis and effective medium modeling
A.H. Reed, K.B. Briggs, D. L. Lavoie
2002, IEEE Journal of Oceanic Engineering (27) 581-592
During the 1999 sediment acoustics experiment (SAX99), porometric properties were measured and predicted for a well sorted, medium sand using standard laboratory geotechnical methods and image analysis of resin-impregnated sediments. Sediment porosity measured by laboratory water-weight-loss methods (0.372 ?? 0.0073 for mean ??1 standard deviation) is 0.026 lower than determined...
Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Nino
A. H. Sallenger Jr., W. Krabill, J. Brock, R. Swift, S. Manizade, H. Stockdon
2002, Marine Geology (187) 279-297
Over time scales of hundreds to thousands of years, the net longshore sand transport direction along the central California coast has been driven to the south by North Pacific winter swell. In contrast, during the El Nin??o winter of 1997-1998, comparisons of before and after airborne lidar surveys showed sand...
Effects of nutrient enrichment on channel catfish growth and consumption in Mount Storm Lake, West Virginia
T.J. Blanc, F.J. Margraf
2002, Lakes and Reservoirs: Research and Management (7) 109-123
With the objective of augmenting fish production in Mount Storm Lake, Virginia Electric and Power Company initiated a programme of phosphorus addition to increase primary production, and ultimately, channel catfish (Ictaturus punctatus) growth in the 486 ha cooling reservoir. We simulated channel catfish growth dynamics using two bioenergetics modelling scenarios:...
Radiation pattern of a borehole radar antenna
K.J. Ellefsen, D.L. Wright
2002, Conference Paper, Proceedings of SPIE - The International Society for Optical Engineering
To understand better how a borehole antenna radiates radar waves into a formation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a...
