Distribution of icy particles across Enceladus' surface as derived from Cassini-VIMS measurements
R. Jaumann, K. Stephan, G. B. Hansen, R. N. Clark, B. J. Buratti, R. H. Brown, K. H. Baines, S.F. Newman, G. Bellucci, G. Filacchione, A. Coradini, D. P. Cruikshank, C.A. Griffith, C. A. Hibbitts, T. B. McCord, R.M. Nelson, P. D. Nicholson, Christophe Sotin, R. Wagner
2008, Icarus (193) 407-419
The surface of Enceladus consists almost completely of water ice. As the band depths of water ice absorptions are sensitive to the size of particles, absorptions can be used to map variations of icy particles across the surface. The Visual and Infrared Mapping Spectrometer (VIMS) observed Enceladus with a high...
A laboratory study of particle ploughing and pore-pressure feedback: A velocity-weakening mechanism for soft glacier beds
J.F. Thomason, N.R. Iverson
2008, Journal of Glaciology (54) 169-181
If basal-water discharge and pressure are sufficiently high, a soft-bedded glacier will slip over its bed by ploughing, the process in which particles that span the ice-bed interface are dragged across the bed surface. Results of laboratory experiments indicate that resistance to ploughing can decrease with increasing ploughing velocity (velocity...
Investigation of flow and transport processes at the MADE site using ensemble Kalman filter
Gaisheng Liu, Y. Chen, Dongxiao Zhang
2008, Advances in Water Resources (31) 975-986
In this work the ensemble Kalman filter (EnKF) is applied to investigate the flow and transport processes at the macro-dispersion experiment (MADE) site in Columbus, MS. The EnKF is a sequential data assimilation approach that adjusts the unknown model parameter values based on the observed data with time. The classic...
Wide-area estimates of stand structure and water use of tamarix spp. on the lower colorado river: Implications for restoration and water management projects
P.L. Nagler, E. P. Glenn, K. Didan, J. Osterberg, F. Jordan, J. Cunningham
2008, Restoration Ecology (16) 136-145
Tamarix spp. removal has been proposed to salvage water and allow native vegetation to recolonize western U.S. riparian corridors. We conducted wide-area studies on the Lower Colorado River to answer some of the scientific questions about Tamarix water use and the consequences of removal, combining ground surveys with remote sensing...
Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA
J. A. Izbicki, J.W. Ball, T.D. Bullen, S. J. Sutley
2008, Applied Geochemistry (23) 1325-1352
Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 μg/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI)...
Breeding stage influences space use of female American avocets in San Francisco Bay, California
Scott A. Demers, M. A. Colwell, John Y. Takekawa, Joshua T. Ackerman
2008, Waterbirds (31) 365-371
Female American Avocets (Recurvirostra americana) were radio-marked (N=15) and tracked in the South San Francisco Bay, California, to determine if space use varied by breeding stage. Visual observations were used to determine breeding stage (pre-incubation, incubation, brood-rearing, post-breeding) of marked avocets. Space use measurements (linear movements, home ranges, core areas,...
Orbital identification of carbonate-bearing rocks on Mars
B.L. Ehlmann, J.F. Mustard, S.L. Murchie, F. Poulet, J.L. Bishop, A.J. Brown, W. M. Calvin, R. N. Clark, D.J. Des Marais, R.E. Milliken, L.H. Roach, T. L. Roush, G.A. Swayze, J.J. Wray
2008, Science (322) 1828-1832
Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Mars Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the Nili Fossae region. The carbonate...
Effects of climate and land management change on streamflow in the driftless area of Wisconsin
P. F. Juckem, R. J. Hunt, Marilyn P. Anderson, Dale M. Robertson
2008, Journal of Hydrology (355) 123-130
Baseflow and precipitation in the Kickapoo River Watershed, located in the Driftless Area of Wisconsin, exhibit a step increase around 1970, similar to minimum and median flows in many other central and eastern USA streams. Potential effects on streamflow due to climatic and land management changes were evaluated by comparing...
Volatile emissions and gas geochemistry of Hot Spring Basin, Yellowstone National Park, USA
C. Werner, S. Hurwitz, William C. Evans, J. B. Lowenstern, D. Bergfeld, H. Heasler, C. Jaworowski, A. Hunt
2008, Journal of Volcanology and Geothermal Research (178) 751-762
We characterize and quantify volatile emissions at Hot Spring Basin (HSB), a large acid-sulfate region that lies just outside the northeastern edge of the 640 ka Yellowstone Caldera. Relative to other thermal areas in Yellowstone, HSB gases are rich in He and H2, and mildly enriched in CH4 and H2S....
Characteristics of mangrove swamps managed for mosquito control in eastern Florida, USA
B. Middleton, D. Devlin, E. Proffitt, Karen McKee, K.F. Cretini
2008, Marine Ecology Progress Series (371) 117-129
Manipulations of the vegetation and hydrology of wetlands for mosquito control are common worldwide, but these modifications may affect vital ecosystem processes. To control mosquitoes in mangrove swamps in eastern Florida, managers have used rotational impoundment management (RIM) as an alternative to the worldwide practice of mosquito ditching. Levees surround...
A fully distributed implementation of mean annual streamflow regional regression equations
K.L. Verdin, B. Worstell
2008, Journal of the American Water Resources Association (44) 1537-1547
Estimates of mean annual streamflow are needed for a variety of hydrologic assessments. Away from gage locations, regional regression equations that are a function of upstream area, precipitation, and temperature are commonly used. Geographic information systems technology has facilitated their use for projects, but traditional approaches using the polygon overlay...
Aquatic macroinvertebrates associated with Schoenoplectus litter in a constructed wetland in California (USA)
S. M. Nelson, J.S. Thullen
2008, Ecological Engineering (33) 91-101
Culm processing characteristics were associated with differences in invertebrate density in a study of invertebrates and senesced culm packs in a constructed treatment wetland. Invertebrate abundance differed by location within the wetland and there were differences between the two study years that appeared to be related to water quality and...
Occurrence and fate of pesticides in four contrasting agricultural settings in the United States
G. V. Steele, H.M. Johnson, Mark W. Sandstrom, P. D. Capel, J.E. Barbash
2008, Journal of Environmental Quality (37) 1116-1132
Occurrence and fate of 45 pesticides and 40 pesticide degradates were investigated in four contrasting agricultural settings—in Maryland, Nebraska, California, and Washington. Primary crops included corn at all sites, soybeans in Maryland, orchards in California and Washington, and vineyards in Washington. Pesticides and pesticide degradates detected in water samples from...
Western juniper and ponderosa pine ecotonal climate-growth relationships across landscape gradients in southern Oregon
K.C. Knutson, D.A. Pyke
2008, Canadian Journal of Forest Research (38) 3021-3032
Forecasts of climate change for the Pacific northwestern United States predict warmer temperatures, increased winter precipitation, and drier summers. Prediction of forest growth responses to these climate fluctuations requires identification of climatic variables limiting tree growth, particularly at limits of free species distributions. We addressed this problem at the pine-woodland...
Northeast storms ranked by wind stress and wave-generated bottom stress observed in Massachusetts Bay, 1990-2006
B. Butman, C. R. Sherwood, P.S. Dalyander
2008, Continental Shelf Research (28) 1231-1245
Along the coast of the northeastern United States, strong winds blowing from the northeast are often associated with storms called northeasters, coastal storms that strongly influence weather. In addition to effects caused by wind stress, the sea floor is affected by bottom stress associated with these storms. Bottom stress caused...
Estimating watershed level nonagricultural pesticide use from golf courses using geospatial methods
G.A. Fox, G.P. Thelin, G.J. Sabbagh, J.W. Fuchs, I.D. Kelly
2008, Journal of the American Water Resources Association (44) 1363-1372
Limited information exists on pesticide use for nonagricultural purposes, making it difficult to estimate pesticide loadings from nonagricultural sources to surface water and to conduct environmental risk assessments. A method was developed to estimate the amount of pesticide use on recreational turf grasses, specifically golf course turf grasses, for watersheds...
Micropaleontologic record of late Pliocene and Quaternary paleoenvironments in the northern Albemarle Embayment, North Carolina, U.S.A.
S.J. Culver, K.M. Farrell, D. J. Mallinson, B. P. Horton, Debra A. Willard, E.R. Thieler, S.R. Riggs, S.W. Snyder, J.F. Wehmiller, C.E. Bernhardt, C. Hillier
2008, Palaeogeography, Palaeoclimatology, Palaeoecology (264) 54-77
Micropaleontological data provide a strong actualistic basis for detailed interpretations of Quaternary paleoenvironmental change. The 90 m-thick Quaternary record of the Albemarle Embayment in the mid-Atlantic coastal plain of the USA provides an excellent opportunity to use such an approach in a region where the details of Quaternary environmental change are...
Longitudinal gradients along a reservoir cascade
L.E. Miranda, M.D. Habrat, S. Miyazono
2008, Transactions of the American Fisheries Society (137) 1851-1865
Reservoirs have traditionally been regarded as spatially independent entities rather than as longitudinal segments of a river system that are connected upstream and downstream to the river and other reservoirs. This view has frustrated advancement in reservoir science by impeding adequate organization of available information and by hindering interchanges with...
Water-quality monitoring and process understanding in support of environmental policy and management
N.E. Peters
2008, Conference Paper, IAHS-AISH Publication
The quantity and quality of freshwater at any point on the landscape reflect the combined effects of many processes operating along hydrological pathways within a drainage basin/watershed/catchment. Primary drivers for the availability of water are landscape changes and patterns, and the processes affecting the timing, magnitude, and intensity of precipitation,...
A survey of the indigenous microbiota (bacteria) in three species of mussels from the Clinch and Holston Rivers, Virginia
Clifford E. Starliper, Richard J. Neves, Shane D. Hanlon, Pamela Whittington
2008, Journal of Shellfish Research (27) 1311-1317
Freshwater mussel conservation efforts by many federal and state agencies have increased in recent years. This has led to a greater number of stream surveys, in which mussel die-offs involving high numbers of dead and moribund animals are being observed and reported with greater frequency. Typically, die-offs have...
Environmental tracers as indicators of karst conduits in groundwater in South Dakota, USA
Andrew J. Long, J.F. Sawyer, L.D. Putnam
2008, Hydrogeology Journal (16) 263-280
Environmental tracers sampled from the carbonate Madison aquifer on the eastern flank of the Black Hills, South Dakota, USA indicated the approximate locations of four major karst conduits. Contamination issues are a major concern because these conduits are characterized by direct connections to sinking streams, high groundwater velocities, and proximity...
An hydrothermal experimental study of the cobalt-cobalt oxide redox buffer
K.H. Lemke, R.J. Rosenbauer, J. L. Bischoff, D.K. Bird
2008, Chemical Geology (252) 136-144
Equilibrium aqueous hydrogen concentration and corresponding energies of reaction, ??Grxno(T, P), for the reaction Co(s) + H2O(l) = CoO(s) + H2(aq) have been determined at temperatures between 256 and 355 ??C and at 400 bar. Steady-state concentrations of hydrogen were approached in experiments under conditions of both H2 excess and...
The A and m coefficients in the Bruun/Dean equilibrium profile equation seen from the Arctic
F. Are, E. Reimnitz
2008, Journal of Coastal Research (24) 243-249
The Bruun/Dean relation between water depth and distance from the shore with a constant profile shape factor is widely used to describe shoreface profiles in temperate environments. However, it has been shown that the sediment scale parameter (A) and the profile shape factor (m) are interrelated variables. An analysis of...
Discrimination of trait-based characteristics by trace element bioaccumulation in riverine fishes
T.M. Short, L.R. DeWeese, N. M. Dubrovsky
2008, Canadian Journal of Fisheries and Aquatic Sciences (65) 1087-1100
Relations between tissue trace element concentrations and species traits were examined for 45 fish species to determine the extent to which trait-based characteristics accounted for relative differences among species in trace element bioaccumulation. Percentages of fish species correctly classified by discriminant analysis according to traits predicted by tissue trace element...
Top predators in relation to bathymetry, ice and krill during austral winter in Marguerite Bay, Antarctica
C. A. Ribic, E. Chapman, William R. Fraser, G.L. Lawson, P.H. Wiebe
2008, Deep-Sea Research Part II: Topical Studies in Oceanography (55) 485-499
A key hypothesis guiding the US Southern Ocean Global Ocean Ecosystems Dynamics (US SO GLOBEC) program is that deep across-shelf troughs facilitate the transport of warm and nutrient-rich waters onto the continental shelf of the Western Antarctic Peninsula, resulting in enhanced winter production and prey availability to top predators. We...
