Methyl mercury dynamics in littoral sediments of a temperate seepage lake
D. P. Krabbenhoft, C.C. Gilmour, J.M. Benoit, Christopher L. Babiarz, A.W. Andren, J.P. Hurley
1998, Canadian Journal of Fisheries and Aquatic Sciences (55) 835-844
The sites and rates of methyl mercury (MeHg) production and transport in littoral zone sediments were investigated at Pallette Lake in northern Wisconsin. In littoral areas where groundwater inflow occurs, sulfate supply from groundwater creates profiles of electron acceptors (sulfate) and donors (methane, sulfide) that are reversed from those found...
Laurentide glacial landscapes: The role of ice streams
C. J. Patterson
1998, Geology (26) 643-646
Glacial landforms of the North American prairie can be divided into two suites that result from different styles of ice flow: (1) a lowland suite of level-to-streamlined till consistent with formation beneath ice streams, and (2) an upland and lobe-margin suite of thick,...
Petrochemistry of late miocene peraluminous silicic volcanic rocks from the Morococala field, Bolivia
VI G.B. Morgan, D. London, R. G. Luedke
1998, Journal of Petrology (39) 601-632
Late Miocene peraluminous volcanic rocks of the Morococala field, Bolivia, define a layered stratigraphy of basal andalusite-, biotite- (± muscovite)-bearing rhyolite tuffs (AR), overlain by cordierite-, biotite-bearing rhyolite tuffs (CR), and capped by biotite-bearing quartz latite tuffs, lavas, and late domal flows (QL). Mineral and whole-rock compositions become more...
Models of metal binding structures in fulvic acid from the Suwannee River, Georgia
J.A. Leenheer, G.K. Brown, P. MacCarthy, S.E. Cabaniss
1998, Environmental Science & Technology (32) 2410-2416
Fulvic acid, isolated from the Suwannee River, Georgia, was assessed for its ability to bind Ca2+, Cd2+, Cu2+, Ni2+, and Zn2+ ions at pH 6 before and after extensive fractionation that was designed to reveal the nature of metal binding functional groups. The binding constant for Ca2+ ion had the...
Assignment of boundary conditions in embedded ground water flow models
S. A. Leake
1998, Groundwater (36) 621-625
Many small-scale ground water models are too small to incorporate distant aquifer boundaries. If a larger-scale model exists for the area of interest, flow and head values can be specified for boundaries in the smaller-scale model using values from the larger-scale model. Flow components along...
Ground-truthing a troll: Studying the barking frog at Coronado National Memorial
C. Schwalbe, B. Alberti
1998, Park Science (18) 26-27
[No abstract available]...
Effect of lead poisoning on spectacled eider survival rates
J. Barry Grand, Paul L. Flint, Margaret R. Petersen, Christine L. Moran
1998, Journal of Wildlife Management (62) 1103-1109
Spectacled eider (Somateria fischeri) populations on the Yukon-Kuskokwim Delta (Y-K Delta), Alaska, declined rapidly through the 1980s, and low adult female survival was suggested as the likely cause of the decline. We used mark-resighting techniques to study annual survival rates of adult female spectacled eiders at 2 sites on the...
A hybrid optimization approach to the estimation of distributed parameters in two-dimensional confined aquifers
M. Heidari, S.R. Ranjithan
1998, Journal of the American Water Resources Association (34) 909-920
ABSTRACT: In using non-linear optimization techniques for estimation of parameters in a distributed ground water model, the initial values of the parameters and prior information about them play important roles. In this paper, the genetic algorithm (GA) is combined with the truncated-Newton search technique to estimate...
Evidence from Lake Baikal for Siberian glaciation during oxygen-isotope substage 5d
E.B. Karabanov, A.A. Prokopenko, D. F. Williams, Steven M. Colman
1998, Quaternary Research (50) 46-55
The paleoclimatic record from bottom sediments of Lake Baikal (eastern Siberia) reveals new evidence for an abrupt and intense glaciation during the initial part of the last interglacial period (isotope substage 5d). This glaciation lasted about 12 000 yr from 117 000 to 105 000 yr BP according to correlation...
Seasonal uranium distributions in the coastal waters off the Amazon and Mississippi Rivers
P.W. Swarzenski, B.A. McKee
1998, Estuaries (21) 379-390
The chemical reactivity of uranium was investigated across estuarine gradients from two of the world’s largest river systems: the Amazon and Mississippi. Concentrations of dissolved (<0.45 μm) uranium (U) were measured in surface waters of the Amazon shelf during rising (March 1990), flood (June 1990) and low (November 1991) discharge...
Comparison of streambed sediment and aquatic biota as media for characterizing trace elements and organochlorine compounds in the Willamette Basin, Oregon
D.A. Wentz, I.R. Waite, F. A. Rinella
1998, Environmental Monitoring and Assessment (51) 673-693
During 1992-93, 27 organochlorine compounds (pesticides plus total PCB) and 17 trace elements were analyzed in bed sediment and aquatic biota from 20 stream sites in the Willamette Basin as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Data from each medium were compared to evaluate their relative...
Deducing growth mechanisms for minerals from the shapes of crystal size distributions
D. D. Eberl, V. A. Drits, J. Srodon
1998, American Journal of Science (298) 499-533
Crystal size distributions (CSDs) of natural and synthetic samples are observed to have several distinct and different shapes. We have simulated these CSDs using three simple equations: the Law of Proportionate Effect (LPE), a mass balance equation, and equations for Ostwald ripening. The following crystal growth mechanisms are simulated using...
Sequence analysis of the mitochondrial DNA control region of ciscoes (genus Coregonus): Taxonomic implications for the Great Lakes species flock
Kent M. Reed, Michael O. Dorschner, Thomas N. Todd, Ruth B. Phillips
1998, Molecular Ecology (7) 1091-1096
Sequence variation in the control region (D-loop) of the mitochondrial DNA (mtDNA) was examined to assess the genetic distinctiveness of the shortjaw cisco (Coregonus zenithicus). Individuals from within the Great Lakes Basin as well as inland lakes outside the basin were sampled. DNA fragments containing the entire D-loop were amplified...
Transport of agrichemicals to ground and surface water in a small central Indiana watershed
J.M. Fenelon, R.C. Moore
1998, Journal of Environmental Quality (27) 884-894
The occurrence, distribution, concentrations, and pathways of agrichemicals in water were investigated in the Sugar Creek watershed, a poorly drained agricultural watershed typical of many watersheds in the midwestern USA. Water samples from Sugar Creek, two tile drains, and 11 wells along a groundwater flowpath to...
Stable carbon and oxygen isotope record of central Lake Erie sediments
M.J.S. Tevesz, A.L. Spongberg, J. A. Fuller
1998, Journal of Paleolimnology (20) 295-305
Stable carbon and oxygen isotope data from mollusc aragonite extracted from sediment cores provide new information on the origin and history of sedimentation in the southwestern area of the central basin of Lake Erie. Sediments infilling the Sandusky subbasin consist of three lithologic units overlying glacial deposits. The lowest of...
The lizard fauna of Guam's fringing islets: Island biogeography, phylogenetic history, and conservation implications
G. Perry, G.H. Rodda, T. H. Fritts, T.R. Sharp
1998, Global Ecology and Biogeography Letters (7) 353-365
We sampled the lizard fauna of twenty-two small islets fringing the Pacific island of Guam and used these data to shed light on the processes responsible for present-day diversity. Habitat diversity, measured by islet area and vegetation complexity, was significantly correlated with the number of species found on an islet....
Sedimentary facies and environmental ichnology of a ?Permian playa-lake complex in western Argentina
G. Zhang, L.A. Buatois, M.G. Mangano, F.G. Acenolaza
1998, Palaeogeography, Palaeoclimatology, Palaeoecology (138) 221-243
A moderately diverse arthropod icnofauna occurs in ?Permian ephemeral lacustrine deposits of the Paganzo Basin that crop out at Bordo Atravesado, Cuesta de Miranda, western Argentina. Sedimentary successions are interpreted as having accumulated in a playa-lake complex. Deposits include three sedimentary facies: (A) laminated siltstone and mudstone: (B) current-rippled cross-laminated...
Rocky 7 prototype Mars rover field geology experiments: 1. Lavic Lake and Sunshine volcanic field, California
R. E. Arvidson, C. Acton, D. Blaney, J. Bowman, S. Kim, G. Klingelhofer, J. Marshall, C. Niebur, J. Plescia, R.S. Saunders, C.T. Ulmer
1998, Journal of Geophysical Research E: Planets (103) 22671-22688
Experiments with the Rocky 7 rover were performed in the Mojave Desert to better understand how to conduct rover-based, long-distance (kilometers) geological traverses on Mars. The rover was equipped with stereo imaging systems for remote sensing science and hazard avoidance and 57Fe Mössbauer and nuclear magnetic resonance spectrometers for in situ...
How organisms do the right thing: The attractor hypothesis
J.M. Emlen, D.C. Freeman, A. Mills, J.H. Graham
1998, Chaos (8) 717-726
Neo-Darwinian theory is highly successful at explaining the emergence of adaptive traits over successive generations. However, there are reasons to doubt its efficacy in explaining the observed, impressively detailed adaptive responses of organisms to day-to-day changes in their surroundings. Also, the theory lacks a clear mechanism to account for both...
Biomarker generation from Type II-S kerogens in claystone and limestone during hydrous and anhydrous pyrolysis
M.P. Koopmans, F.C. Carson, Damste J.S. Sinninghe, M. D. Lewan
1998, Conference Paper, Organic Geochemistry
A claystone and a limestone containing immature Type II-S kerogen were thermally matured in the presence and absence of water, to study the influence of water and clay minerals on the generation of biomarkers. In contrast to hydrous pyrolysis, anhydrous pyrolysis of the claystone did not generate biomarkers, which resulted...
Carbon isotopic comparisons of oil products used in the developmental history of Alaska
K.A. Kvenvolden, P.R. Carlson, A. Warden, C. N. Threlkeld
1998, Chemical Geology (152) 73-84
Studies of the fate of oil released into Prince William Sound, AK, as a result of the 1989 Exxon Valdez oil spill, have led to an unexpected discovery. In addition to oil-like residues attributed to the spill, the ubiquitous presence of flattened tar balls, the carbon isotopic compositions of which...
Estimation of Mars radar backscatter from measured surface rock populations
J.E. Baron, R.A. Simpson, G.L. Tyler, H. J. Moore, J.K. Harmon
1998, Journal of Geophysical Research E: Planets (103) 22695-22712
Reanalysis of rock population data at the Mars Viking Lander sites has yielded updated values of rock fractional surface coverage (about 0.16 at both sites, including outcrops) and new estimates of rock burial depths and axial ratios. These data are combined with a finite difference time domain (FDTD) numerical scattering...
Small-scale morphology across the surf zone
E.B. Thornton, J.L. Swayne, J.R. Dingler
1998, Marine Geology (145) 173-196
Small-scale (< 5 m horizontal length) nearshore morphologic height variations were measured by combining CRAB surveys with bed elevations acquired with a 1 MHz sonic altimeter mounted on the CRAB during the October Phase of the DUCK94 experiment. Bedform plan views were recorded simultaneously using a 500 kHz side-scan sonar...
The Soufriere Hills eruption, Montserrat, British West Indies: Introduction to special section, part 1
W. P. Aspinall, L.L. Lynch, R.E.A. Robertson, K. Rowley, R. S. J. Sparks, B. Voight, S.R. Young
1998, Geophysical Research Letters (25) 3651-3651
The special section on the eruption of Soufriere Hills volcano is a collection of 24 papers that summarises the early scientific work of the Montserrat Volcano Observatory. Part 1 of the special section, published in a previous issue of GRL, provided a sampling of the multidisciplinary investigations...
Cotton herbicides in the surface waters of the Mississippi Alluvial Plain (the Delta)
R.H. Coupe, R.A. Rebich
1998, Conference Paper, International Water Resources Engineering Conference - Proceedings
The U.S. Geological Survey is conducting two studies to assess the environmental fate of herbicides used in cotton producing areas of the southeastern United States. The first study is evaluating surface-water quality on a regional basis and relating water quality to land use. The second study is examining the use...
