An evaluation of a reagentless method for the determination of total mercury in aquatic life
Sekeenia Haynes, Richard D. Gragg, Elijah Johnson, Larry Robinson, Carl E. Orazio
2006, Water, Air, & Soil Pollution (172) 359-374
Multiple treatment (i.e., drying, chemical digestion, and oxidation) steps are often required during preparation of biological matrices for quantitative analysis of mercury; these multiple steps could potentially lead to systematic errors and poor recovery of the analyte. In this study, the Direct Mercury Analyzer (Milestone Inc., Monroe, CT) was utilized...
Distribution and sources of surfzone bacteria at Huntington Beach before and after disinfection on an ocean outfall - A frequency-domain analysis
M.A. Noble, J. P. Xu, G.L. Robertson, L.K. Rosenfeld
2006, Marine Environmental Research (61) 494-510
Fecal indicator bacteria (FIB) were measured approximately 5 days a week in ankle-depth water at 19 surfzone stations along Huntington Beach and Newport Beach, California, from 1998 to the end of 2003. These sampling periods span the time before and after treated sewage effluent, discharged into the coastal ocean from...
Distribution of stress drop, stiffness, and fracture energy over earthquake rupture zones
Joe B. Fletcher, Art McGarr
2006, Journal of Geophysical Research B: Solid Earth (111)
Using information provided by slip models and the methodology of McGarr and Fletcher (2002), we map static stress drop, stiffness (k = ????/u, where ???? is static stress drop and u is slip), and fracture energy over the slip surface to investigate the earthquake rupture process and energy budget. For...
Fracture in Westerly granite under AE feedback and constant strain rate loading: Nucleation, quasi-static propagation, and the transition to unstable fracture propagation
B.D. Thompson, R.P. Young, D.A. Lockner
2006, Conference Paper, Pure and Applied Geophysics
New observations of fracture nucleation are presented from three triaxial compression experiments on intact samples of Westerly granite, using Acoustic Emission (AE) monitoring. By conducting the tests under different loading conditions, the fracture process is demonstrated for quasi-static fracture (under AE Feedback load), a slowly developing unstable fracture (loaded at...
Tectonic stressing in California modeled from GPS observations
T. Parsons
2006, Journal of Geophysical Research B: Solid Earth (111)
What happens in the crust as a result of geodetically observed secular motions? In this paper we find out by distorting a finite element model of California using GPS-derived displacements. A complex model was constructed using spatially varying crustal thickness, geothermal gradient, topography, and creeping faults. GPS velocity observations were...
Ammonium transport and reaction in contaminated groundwater: Application of isotope tracers and isotope fractionation studies
J.K. Böhlke, Richard L. Smith, Daniel N. Miller
2006, Water Resources Research (42)
Ammonium (NH4+) is a major constituent of many contaminated groundwaters, but its movement through aquifers is complex and poorly documented. In this study, processes affecting NH4+ movement in a treated wastewater plume were studied by a combination of techniques including large‐scale monitoring of NH4+ distribution; isotopic analyses of coexisting aqueous NH4+, NO3−,...
Impacts of aircraft deicer and anti-icer runoff on receiving waters from Dallas/Fort Worth International Airport, Texas, USA
S.R. Corsi, G.R. Harwell, S.W. Geis, D. Bergman
2006, Environmental Toxicology and Chemistry (25) 2890-2900
From October 2002 to April 2004, data were collected from Dallas/Fort Worth (DFW) International Airport (TX, USA) outfalls and receiving waters (Trigg Lake and Big Bear Creek) to document the magnitude and potential effects of aircraft deicer and anti-icer fluid (ADAF) runoff on water quality. Glycol concentrations at outfalls ranged...
Using Modified Mercalli Intensities to estimate acceleration response spectra for the 1906 San Francisco earthquake
J. Boatwright, H. Bundock, L. C. Seekins
2006, Earthquake Spectra (22)
We derive and test relations between the Modified Mercalli Intensity (MMI) and the pseudo-acceleration response spectra at 1.0 and 0.3 s - SA(1.0 s) and SA(0.3 s) - in order to map response spectral ordinates for the 1906 San Francisco earthquake. Recent analyses of intensity have shown that MMI ???...
Differences in tsunami generation between the December 26, 2004 and March 28, 2005 Sumatra earthquakes
E.L. Geist, S.L. Bilek, D. Arcas, V.V. Titov
2006, Earth, Planets and Space (58) 185-193
Source parameters affecting tsunami generation and propagation for the Mw > 9.0 December 26, 2004 and the Mw = 8.6 March 28, 2005 earthquakes are examined to explain the dramatic difference in tsunami observations. We evaluate both scalar measures (seismic moment, maximum slip, potential energy) and finite-source repre-sentations (distributed slip...
Northern Florida reef tract benthic metabolism scaled by remote sensing
J. C. Brock, K. K. Yates, R. B. Halley, I. B. Kuffner, C. W. Wright, B.G. Hatcher
2006, Marine Ecology Progress Series (312) 123-139
Holistic rates of excess organic carbon production (E) and calcification for a 0.5 km2 segment of the backreef platform of the northern Florida reef tract (NFRT) were estimated by combining biotope mapping using remote sensing with community metabolic rates determined with a benthic incubation system. The use of ASTER multispectral...
Demographic patterns and harvest vulnerability of chronic wasting disease infected white-tailed deer in Wisconsin
D.A. Grear, M.D. Samuel, J.A. Langenberg, D. Keane
2006, Journal of Wildlife Management (70) 546-553
Chronic wasting disease (CWD) is a fatal disease of white-tailed deer (Odocoileus virginianus) caused by transmissible protease-resistant prions. Since the discovery of CWD in southern Wisconsin in 2001, more than 20,000 deer have been removed from a >2,500-km2 disease eradication zone surrounding the three initial cases. Nearly all deer removed...
Modelling river discharge and precipitation from estuarine salinity in the northern Chesapeake Bay: Application to Holocene palaeoclimate
C. Saenger, T. Cronin, R. Thunell, C. Vann
2006, Holocene (16) 467-477
Long-term chronologies of precipitation can provide a baseline against which twentieth-century trends in rainfall can be evaluated in terms of natural variability and anthropogenic influence. However, there are relatively few methods to quantitatively reconstruct palaeoprecipitation and river discharge compared with proxies of other climatic factors, such as temperature. We developed...
Public expectations about access fees and road closures on public lands
K. Cline, B. L. Lamb, P.D. Ponds
2006, Journal of Environmental Planning and Management (49) 227-240
It is sometimes suggested that land managers could better communicate with the general public by relying on people who are active in community affairs to frame the message. By comparing responses from the 'attentive' and general public on the Colorado Plateau in the USA, this study investigated the expected effects...
Design and application of an electromagnetic vibrator seismic source
S.S. Haines
2006, Journal of Environmental & Engineering Geophysics (11) 9-15
Vibrational seismic sources frequently provide a higher-frequency seismic wavelet (and therefore better resolution) than other sources, and can provide a superior signal-to-noise ratio in many settings. However, they are often prohibitively expensive for lower-budget shallow surveys. In order to address this problem, I designed and built a simple but effective...
Rocks of the Columbia Hills
S. W. Squyres, R. E. Arvidson, D.L. Blaney, B. C. Clark, L. Crumpler, W. H. Farrand, S. Gorevan, Kenneth E. Herkenhoff, J. Hurowitz, A. Kusack, H.Y. McSween, D. W. Ming, R.V. Morris, S. W. Ruff, A. Wang, A. Yen
2006, Journal of Geophysical Research E: Planets (111)
The Mars Exploration Rover Spirit has identified five distinct rock types in the Columbia Hills of Gusev crater. Clovis Class rock is a poorly sorted clastic rock that has undergone substantial aqueous alteration. We interpret it to be aqueously altered ejecta deposits formed by impacts into basaltic materials. Wishstone Class...
Numerical modeling of a long-term in situ chemical osmosis experiment in the Pierre Shale, South Dakota
A.M. Garavito, H. Kooi, C. E. Neuzil
2006, Advances in Water Resources (29) 481-492
We have numerically modeled evolving fluid pressures and concentrations from a nine-year in situ osmosis experiment in the Pierre Shale, South Dakota. These data were obtained and recently interpreted by one of us (C.E.N.) as indicating a potentially significant role for chemical osmosis in media like the Pierre Shale. That...
Beaver dams and overbank floods influence groundwater-surface water interactions of a Rocky Mountain riparian area
Cherie J. Westbrook, David J. Cooper, Bruce W. Baker
2006, Water Resources Research (42)
Overbank flooding is recognized by hydrologists as a key process that drives hydrogeomorphic and ecological dynamics in mountain valleys. Beaver create dams that some ecologists have assumed may also drive riparian hydrologic processes, but empirical evidence is lacking. We examined the influence of two in‐channel beaver dams and a 10...
Geomorphic control of landscape carbon accumulation
N.A. Rosenbloom, J.W. Harden, J. C. Neff, D. S. Schimel
2006, Journal of Geophysical Research G: Biogeosciences (111)
We use the CREEP process-response model to simulate soil organic carbon accumulation in an undisturbed prairie site in Iowa. Our primary objectives are to identify spatial patterns of carbon accumulation, and explore the effect of erosion on basin-scale C accumulation. Our results point to two general findings. First, redistribution of...
Effects of Chinese mineral strategies on the U.S. minerals industry
L. McCartan, W. D. Menzie, D.E. Morse, J.F. Papp, P.A. Plunkert, P.-K. Tse
2006, Mining Engineering (58) 37-42
For more than two decades now, China has been undergoing rapid economic growth and industrialization. The industrialization and urbanization of the once rural, farming nation is leading to increased consumption of mineral commodities to build infrastructure and to make into consumer goods. This increased consumption has led to higher mineral...
Characteristics of a ringtail (Bassariscus astutus) population in Trans Pecos, Texas
B.K. Ackerson, L.A. Harveson
2006, Texas Journal of Science (58) 169-184
Despite the common occurrence of ringtails (Bassariscus astutus) few studies have been conducted to assess population characteristics. The objectives of this study were to determine (1) habitat selection, (2) home range, (3) denning characteristics, and (4) food habits of ringtails in the Trans Pecos region of west Texas. Seventeen ringtails...
Timing of late Holocene surface rupture of the Wairau Fault, Marlborough, New Zealand
J. Zachariasen, K. Berryman, Rob Langridge, C. Prentice, M. Rymer, M. Stirling, P. Villamor
2006, New Zealand Journal of Geology and Geophysics (49) 159-174
Three trenches excavated across the central portion of the right-lateral strike-slip Wairau Fault in South Island, New Zealand, exposed a complex set of fault strands that have displaced a sequence of late Holocene alluvial and colluvial deposits. Abundant charcoal fragments provide age control for various stratigraphic horizons dating back to...
Interferometric synthetic aperture radar: Building tomorrow's tools today
Zhong Lu
2006, Alaska Satellite Facility News and Notes (15) 12-14
A synthetic aperture radar (SAR) system transmits electromagnetic (EM) waves at a wavelength that can range from a few millimeters to tens of centimeters. The radar wave propagates through the atmosphere and interacts with the Earth’s surface. Part of the energy is reflected back to the SAR system and recorded....
Biofouling and the continuous monitoring of underwater light from a seagrass perspective
C.P. Onuf
2006, Estuaries and Coasts (29) 511-518
For more than a decade, inexpensive electronic instruments have made continuous underwater light monitoring an integral part of many seagrass studies. Although biofouling, if not controlled, compromises the utility of the record. A year-long assessment of the time course of sensor fouling, in the Laguna Madre of Texas established that...
Explosion source strong ground motions in the Mississippi embayment
C.A. Langston, P. Bodin, C. Powell, M. Withers, S. Horton, Walter D. Mooney
2006, Bulletin of the Seismological Society of America (96) 1038-1054
Two strong-motion arrays were deployed for the October 2002 Embayment Seismic Excitation Experiment to study the spatial variation of strong ground motions in the deep, unconsolidated sediments of the Mississippi embayment because there are no comparable strong-motion data from natural earthquakes in the area. Each linear array consisted of eight...
Bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem
L.J. Sperry, Jayne Belnap, R.D. Evans
2006, Ecology (87) 603-615
The nonnative annual grass Bromus tectorum has successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical disturbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations...
