Time-averaged fluxes of lead and fallout radionuclides to sediments in Florida Bay
J. A. Robbins, C. Holmes, R. Halley, Michael H. Bothner, E. Shinn, J. Graney, G. Keeler, M. TenBrink, K.A. Orlandini, D. Rudnick
2000, Journal of Geophysical Research C: Oceans (105) 28805-28821
Recent, unmixed sediments from mud banks of central Florida Bay were dated using 210Pb/226Ra, and chronologies were verified by comparing sediment lead temporal records with Pb/Ca ratios in annual layers of coral (Montastrea annularis) located on the ocean side of the Florida Keys. Dates of sediment lead peaks (1978±2) accord...
Post-release attributes and survival of hatchery and natural fall Chinook salmon in the Snake River
K.F. Tiffan, D.W. Rondorf, H.L. Burge
2000, Report
Abstract not available...
Quantification and regionalization of groundwater recharge in South-Central Kansas: Integrating field characterization, statistical analysis, and GIS
M. Sophocleous
2000, The Compass: Earth Science Journal of Sigma Gamma Epsilon (75) 101-115
A practical methodology for recharge characterization was developed based on several years of field-oriented research at 10 sites in the Great Bend Prairie of south-central Kansas. This methodology combines the soil-water budget on a storm-by-storm year-round basis with the resulting watertable rises. The estimated 1985-1992 average annual recharge was less...
Record of late holocene debris avalanches and lahars at Iliamna Volcano, Alaska
C. F. Waythomas, T. P. Miller, J. E. Beget
2000, Journal of Volcanology and Geothermal Research (104) 97-130
Iliamna Volcano is a 3053-meter high, glaciated stratovolcano in the southern Cook Inlet region of Alaska and is one of seven volcanoes in this region that have erupted multiple times during the past 10,000 yr. Prior to our studies of Iliamna Volcano, little was known about the frequency, magnitude, and...
Stream chemistry modeling of two watersheds in the Front Range, Colorado
Thomas Meixner, Roger C. Bales, Mark W. Williams, Donald H. Campbell, Jill S. Baron
2000, Water Resources Research (36) 77-87
We investigated the hydrologic, geochemical, and biogeochemical controls on stream chemical composition on the Green Lakes Valley and Andrews Creek watersheds using the alpine hydrochemical model (AHM). Both sites had comparable data sets from 1994 and 1996, including high‐resolution spatial data and high‐frequency time series of hydrology, geochemistry, and meteorology....
USGS research on three mid-latitude glaciers
J.R. Green, L. DeWayne Cecil, D. L. Naftz, P. F. Schuster
2000, Conference Paper, Proceedings of The Western Snow Conference
Low- and mid-latitude regions of the earth are home to 80 to 90 percent of the world's population. Because of this, the U.S. Geological Survey (USGS) is conducting a research program to study the geochemistry of precipitation, snow, ice, and runoff samples from mid-latitude glaciers in Kyrghyzstan, Nepal, and the...
Effects of asynchronous snowmelt on flushing of dissolved organic carbon: A mixing model approach
E.W. Boyer, G.M. Hornberger, K.E. Bencala, Diane M. McKnight
2000, Hydrological Processes (14) 3291-3308
In many snowmelt-dominated catchments, stream dissolved organic carbon (DOC) levels typically increase rapidly as spring melt commences, peak before maximum discharge, and decrease quickly as melting continues. We present data from Deer Creek (Summit County, CO) that shows this distinctive flushing response of DOC during snowmelt runoff, with DOC stored...
Information technology developments within the national biological information infrastructure
Gladys Cotter, Mike Frame
2000, Mathematics and Computers in Modern Science - Acoustics and Music, Biology and Chemistry, Business and Economics 206-211
Looking out an office window or exploring a community park, one can easily see the tremendous challenges that biological information presents the computer science community. Biological information varies in format and content depending whether or not it is information pertaining to a particular species (i.e. Brown Tree Snake), or a...
Richness and diversity of helminth communities in tropical freshwater fishes: Empirical evidence
A. Choudhury, T.A. Dick
2000, Journal of Biogeography (27) 935-956
Aim: Published information on the richness and diversity of helminth parasite communities in tropical freshwater fishes is reviewed in response to expectations of species-rich parasite communities in tropical regions. Location: Areas covered include the tropics and some subtropical areas. In addition, the north temperate area of the nearctic zone is...
Results of the Imager for Mars Pathfinder windsock experiment
Robert Sullivan, Ronald Greeley, Michael Kraft, Gregory Wilson, Matthew P. Golombek, Kenneth E. Herkenhoff, James Murphy, Peter Smith
2000, Journal of Geophysical Research E: Planets (105) 24547-24562
The Imager for Mars Pathfinder (IMP) windsock experiment measured wind speeds at three heights within 1.2 m of the Martian surface during Pathfinder landed operations. These wind data allowed direct measurement of near-surface wind profiles on Mars for the first time, including determination of aerodynamic roughness length and wind friction...
Climatic and biotic controls on annual carbon storage in Amazonian ecosystems
H. Tian, J. M. Melillo, D. W. Kicklighter, A. D. McGuire, J. Helfrich Iii, B. Moore III, C. J. Vorosmarty
2000, Global Ecology and Biogeography (9) 315-335
1 The role of undisturbed tropical land ecosystems in the global carbon budget is not well understood. It has been suggested that inter-annual climate variability can affect the capacity of these ecosystems to store carbon in the short term. In this paper, we use a transient version of the Terrestrial...
Characterization and speciation of mercury-bearing mine wastes using X-ray absorption spectroscopy
C.S. Kim, Gordon E. Brown Jr., J. J. Rytuba
2000, Science of the Total Environment (261) 157-168
Mining of mercury deposits located in the California Coast Range has resulted in the release of mercury to the local environment and water supplies. The solubility, transport, and potential bioavailability of mercury are controlled by its chemical speciation, which can be directly determined for samples with total mercury concentrations greater...
Aseismic inflation of Westdahl volcano, Alaska, revealed by satellite radar interferometry
Z. Lu, Charles Wicks, D. Dzurisin, W. Thatcher, J.T. Freymueller, S.R. McNutt, Dorte Mann
2000, Geophysical Research Letters (27) 1567-1570
Westdahl volcano, located at the west end of Unimak Island in the central Aleutian volcanic arc, Alaska, is a broad shield that produced moderate-sized eruptions in 1964, 1978-79, and 1991-92. Satellite radar interferometry detected about 17 cm of volcano-wide inflation from September 1993 to October 1998. Multiple independent interferograms reveal...
Predation on Corynorhinus townsendii by Rattus rattus
Gary M. Fellers
2000, Southwestern Naturalist (45) 524-527
Corynorhinus townsendii (Townsend's big- eared bat) is a rare and declining species. Ex- tensive surveys for the coastal subspecies, C. t. townsendii, in California indicate that only 50% of historic maternity colonies are occu- pied currently (Pierson and Rainey, 1996). Three of the largest maternity colonies occur in Marin...
Sediment loads and accumulation in a small riparian wetland system in northern Missouri
David C. Heimann, Michael J. Roell
2000, Wetlands (20) 219-231
Sediment transport and deposition along a stream in an agricultural basin (65 km2) in northern Missouri, USA were quantified as part of a long-term study to evaluate effects of silvicultural practices on the hydrology, sediment, vegetation, and wildlife characteristics of remaining forested riparian systems. Median cumulative sediment deposition, measured using...
Relation of pathways and transit times of recharge water to nitrate concentrations using stable isotopes
M.K. Landon, G. N. Delin, S.C. Komor, C.P. Regan
2000, Ground Water (38) 381-395
Oxygen and hydrogen stable isotope values of precipitation, irrigation water, soil water, and ground water were used with soil-moisture contents and water levels to estimate transit times and pathways of recharge water in the unsaturated zone of a sand and gravel aquifer. Nitrate-nitrogen (nitrate) concentrations in ground water were also...
Martian oceans, valleys and climate
M. H. Carr
2000, Astronomy and Geophysics (41) 320-326
The new Mars Global Surveyor altimetry shows that the heavily cratered southern hemisphere of Mars is 5 km higher that the sparely cratered plains of the northern hemisphere. Previous suggestions that oceans formerly occupied that northern plains as evidenced by shorelines are partly supported by the new data. A previously...
Depositional history of organic contaminants on the Palos Verdes Shelf, California
R.P. Eganhouse, J. Pontolillo
2000, Marine Chemistry (70) 317-338
During more than 60 years, sedimentation on the Palos Verdes Shelf has been dominated by time-varying inputs of municipal wastewater from the Los Angeles County Sanitation Districts (LACSD) and debris from the Portuguese Bend Landslide (PBL). The present study examines the depositional history of wastewater-derived organic contaminants at a site...
Selenium stable isotope ratios as indicators of sources and cycling of selenium: Results from the northern reach of San Francisco Bay
T.M. Johnson, T.D. Bullen, P.T. Zawislanski
2000, Environmental Science & Technology (34) 2075-2079
Selenium stable isotope ratios can serve as indicators of Se sources and reduction of Se oxyanions, much as sulfur and nitrogen isotope ratios do in sulfur and nitrogen biogeochemical studies. A new analytical method, which allows precise Se isotope ratio measurements on 500 ng of Se, greatly enhances analysis of...
Intensification of the Northeast Pacific oxygen minimum zone during the Bölling-Alleröd warm period
Yen Zheng, Alexander van Geen, Robert F. Anderson, James V. Gardner, Walter E. Dean
2000, Paleoceanography (15) 528-536
Although climate records from several locations around the world show nearly synchronous and abrupt changes, the nature of the inferred teleconnection is still poorly understood. On the basis of preserved laminations and molybdenum enrichments in open margin sediments we demonstrate that the oxygen content of northeast Pacific waters at 800...
Winter survival of adult female harlequin ducks in relation to history of contamination by the Exxon Valdez oil spill
Daniel Esler, Joel A. Schmutz, R. L. Jarvis, D.M. Mulcahy
2000, Journal of Wildlife Management (64) 839-847
Harlequin duck (Histrionicus histrionicus) life-history characteristics make their populations particularly vulnerable to perturbations during nonbreeding periods. The 1989 Exxon Valdez oil spill was a major perturbation to nonbreeding habitats of harlequin ducks in Prince William Sound, Alaska, which resulted in population injury. To assess the status of population recovery from...
Apparent inferiority of first-time breeders in the kittiwake: The role of heterogeneity among age classes
E. Cam, J. #NAME? Monnat
2000, Journal of Animal Ecology (69) 380-394
1. Many studies have provided evidence that first-time breeders have a lower survival, a lower probability of success, or of breeding, in the following year. Hypotheses based on reproductive costs have often been proposed to explain this. However, because of the intrinsic relationship between age and experience, the apparent inferiority...
Hydrothermal diamond anvil cell for XAFS studies of first-row transition elements in aqueous solutions up to supercritical conditions
William A. Bassett, Alan J. Anderson, Robert A. Mayanovic, I.-M. Chou
2000, Conference Paper, Chemical Geology
A hydrothermal diamond anvil cell (HDAC) has been modified by drilling holes with a laser to within 150 ??m of the anvil face to minimize the loss of X-rays due to absorption and scatter by diamond. This modification enables acquisition of K-edge X-ray absorption fine structure (XAFS) spectra from first-row...
Surface ages and resurfacing rates of the Polar Layered Deposits on Mars
Kenneth E. Herkenhoff, Jeffrey J. Plaut
2000, Icarus (144) 243-253
Interpretation of the polar stratigraphy of Mars in terms of global climate changes is complicated by the significant difference in surface ages between the north and south polar layered terrains inferred from crater statistics. We have reassessed the cratering record in both polar regions using Viking Orbiter and Mariner 9 images. No craters have...
Map data in support of forest management
E. A. Fosnight, D. Greenlee
2000, Journal of Forestry (98) 50-52
Now widely available and inexpensive, prepackaged map data are easy to use--and just as easy to use incorrectly. To select the proper scale and appropriate thematic attributes so that the data actually inform the project at hand, managers need to know the basics....
