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Articles 15961 - 15990 of 17792
Full-Text Articles in Entire DC Network
Application Of Biophysical Data To An Unsupervised Classification To Map Ecoregional Boundaries In The Desert Southwest, Paxton R. Mcclurg
Application Of Biophysical Data To An Unsupervised Classification To Map Ecoregional Boundaries In The Desert Southwest, Paxton R. Mcclurg
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
An unsupervised classification was applied to continuous biophysical variables in an attempt to delineate ecoregional boundaries in the desert southwest. Output was then compared with ecoregions delineated by the Natural Resources Conservation Service (NRCS), the Environmental Protection Agency (EPA), and the Forest Service at the national level. An attempt was made to use the same biophysical variables for input into the unsupervised classification as was emphasized by the various agencies with their ecoregional classifications at the desert level. Major constraints included data availability at such a large study area, data resolution, and data that were continuous. This eliminated categorical data …
Coalbed Methane Development In Wyoming’S Powder River Basin, Diana Hulme
Coalbed Methane Development In Wyoming’S Powder River Basin, Diana Hulme
Coalbed Methane Development in the Intermountain West (April 4-5)
21 pages (includes color illustrations and maps).
Contains endnotes.
Chemical, Isotopic, And Hydrogeologic Investigations Of An Agriculturally Impacted Area, Nottawa Creek Watershed, Calhoun County, Michigan, Gerald A. Unterreiner
Chemical, Isotopic, And Hydrogeologic Investigations Of An Agriculturally Impacted Area, Nottawa Creek Watershed, Calhoun County, Michigan, Gerald A. Unterreiner
Dissertations
A 4 km2 agricultural area within the somewhat poorly drained Nottawa Creek Watershed, south central Michigan, was investigated to help understand transport and transformation processes of nutrients and herbicides to surface water. Geology o f the study area is comprised of a thin glacial drift cover overlying shale bedrock. A one layer, two-dimensional numerical triangular finite element groundwater flow model was developed to evaluate regional groundwater flow. Selected horizontal hydraulic conductivities ranged from 3 x 10‘3 m/day to 107 m/day. Field-scale infiltration modeling with the computer program GLEAMS, substantiated with water level measurements, suggest significant recharge events occur during summer, …
Plant Establishment With Rainfall Simulators For Erosion Control, Brent Hallock, Steve Rein, Misty Scharff, Michael Curto
Plant Establishment With Rainfall Simulators For Erosion Control, Brent Hallock, Steve Rein, Misty Scharff, Michael Curto
Earth and Soil Sciences
Hydroseeding failures on disturbed sites are usually attributable to combinations of improper species selection, seeding at inappropriate times, and/or improper seed mixes, fiber, and tackifier. To investigate these factors, California Polytechnic State University, San Luis Obispo, in conjunction with the California Department of Transportation (Caltrans) and California State University, Sacramento, conducted a study of these factors’ affect on vegetation establishment.
The goal was to identify initially fast growing vegetation that demonstrates long-term erosion control effectiveness. Native plant species common to District 5, along the California Central Coast, were used. Treatments were conducted in 0.6 by 2 m by 30 cm …
A Gis To Select Plant Species For Erosion Control Along California Highways, Michael Curto, Brent Hallock, Misty Scharff
A Gis To Select Plant Species For Erosion Control Along California Highways, Michael Curto, Brent Hallock, Misty Scharff
Earth and Soil Sciences
Through road construction and maintenance activities, the California Department of Transportation (Caltrans) actively manages roadside rights-of-way that transect California's 41 million hectares (101 million acres), spanning over 3,000 meters of elevational change from seashore to subalpine. State and federal highways are grouped into 12 districts, each encompassing from one to 11 of the state's 58 counties. District personnel are typically responsible for implementing site-specific adaptations of general statewide guidelines for shortto long-term erosion control following construction or storm damage. Many erosion control projects involve reestablishing vegetation through seeding where the precarious life stages of germination and establishment are controlled by …
Crop Updates 2002 - Farming Systems, Peter Metcalfe, Mike Ewing, Roy Latta, Keith Devenish, Diana Fedorenko, Clayton Butterly, Chantelle Butterly, Kim Diamond, Neil Diamond, Stuart Mcalpine, Bill Bowden, Jessica Johns, Terry Piper, David Bowran, Robert Beard, Phil Ward, Dominie Wright, Nichole Burges, Roger Jones, Danae Harman, Greg Shea, George Yan, David Tennant, David Hall, Anyou Liu, Clinton Revell, Candy Hudson, Andrew Blake, Natalie Lauritsen, John Fosu-Nyarko, Roger Jones, Lisa Smith, Mike Jones, Geoff Dwyer, Bill Bowden, Michael O'Connell, Chris Gazey, David Gartner, Amanda Miller, Richard W. Bell, K. Frost, Mike Wong, Ross Brennan, N. J. Blake, G. Mconnell, D. Patabendige, N. Venn, Derk Bakker, Greg Hamilton, Dave Houlbrooke, Cliff Spann, Paul Blackwell, Bindi Webb, G. Lyle, K. Wittwer, Perry Dolling, Senthold Asseng, Ian Fillery, Michael Robertson, Caroline Peek, David Rogers, Peter Portman, Jeff Russell, Greg Shea, Ben Henderson, Ross Kingwell, Tresslyn Walmsley, Jean Galloway, Debbie Thackray, Moin Salam, Art Diggle, William J. Macleod, Jenny Hawkes
Crop Updates 2002 - Farming Systems, Peter Metcalfe, Mike Ewing, Roy Latta, Keith Devenish, Diana Fedorenko, Clayton Butterly, Chantelle Butterly, Kim Diamond, Neil Diamond, Stuart Mcalpine, Bill Bowden, Jessica Johns, Terry Piper, David Bowran, Robert Beard, Phil Ward, Dominie Wright, Nichole Burges, Roger Jones, Danae Harman, Greg Shea, George Yan, David Tennant, David Hall, Anyou Liu, Clinton Revell, Candy Hudson, Andrew Blake, Natalie Lauritsen, John Fosu-Nyarko, Roger Jones, Lisa Smith, Mike Jones, Geoff Dwyer, Bill Bowden, Michael O'Connell, Chris Gazey, David Gartner, Amanda Miller, Richard W. Bell, K. Frost, Mike Wong, Ross Brennan, N. J. Blake, G. Mconnell, D. Patabendige, N. Venn, Derk Bakker, Greg Hamilton, Dave Houlbrooke, Cliff Spann, Paul Blackwell, Bindi Webb, G. Lyle, K. Wittwer, Perry Dolling, Senthold Asseng, Ian Fillery, Michael Robertson, Caroline Peek, David Rogers, Peter Portman, Jeff Russell, Greg Shea, Ben Henderson, Ross Kingwell, Tresslyn Walmsley, Jean Galloway, Debbie Thackray, Moin Salam, Art Diggle, William J. Macleod, Jenny Hawkes
Crop Updates
This session covers forty one papers from different authors:
INTRODUCTION
1. Future Farming Systems session for Crop Updates 2002 Peter Metcalf, FARMING SYSTEMS SUBPROGRAM MANAGER GRAINS PROGRAM Department of Agriculture
2. Perennial pastures in annual cropping systems: Lucerne and beyond, the ‘Big Picture’, Mike Ewing, Deputy CEO CRC for Plant-based Management of Dryland Salinity, Department of Agriculture
3. Perennial pastures in annual cropping systems: lucerne and beyond, Roy Latta and Keith Devenish, Department of Agriculture
4. Establishing Lucerne with a cover crop, Diana Fedorenko1, Clayton Butterly1, Chantelle Butterly1, Kim and Neil Diamond2 …
Equatorial Ocean Circulation In An Extremely Warm Climate, T. C. Moore, D. K. Rea, Mitchell W. Lyle, Lee M. Liberty
Equatorial Ocean Circulation In An Extremely Warm Climate, T. C. Moore, D. K. Rea, Mitchell W. Lyle, Lee M. Liberty
CGISS Publications and Presentations
The warm climates of the early Paleogene and the associated diminished near-surface winds should have resulted in a reduction in near-surface ocean circulation. One check on this deduction is the delineation of biogenic sediments associated with an equatorial current system of the early Eocene Pacific. A latitudinal seismic reflection transect across the tropical Pacific along early Paleogene ocean crust reveals a basal high-amplitude reflection package that we take to be the lower Eocene section. This unit varies in thickness by a factor of about two, with the thickest portion forming a low mound some 3˚–4˚ north of the 56 Ma …
Synchrotron Radiation-Induced X-Ray Emission To Identify Metal Ions In Preparations Of Purified Protein, Thomas Pfister, Huan Feng, Eckard Wimmer, Keith W. Jones
Synchrotron Radiation-Induced X-Ray Emission To Identify Metal Ions In Preparations Of Purified Protein, Thomas Pfister, Huan Feng, Eckard Wimmer, Keith W. Jones
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
The suitability of synchrotron radiation-induced X-ray emission (SRIXE) for the detection and identification of metal ions in preparations of purified, soluble proteins was tested. Glutathione S-transferase fused to the proximal zinc finger motif of human transcription factor IIIA or to the cysteine-rich motif of poliovirus protein 2C was expressed in bacteria and purified by affinity chromatography. Aqueous samples containing the purified proteins were analyzed with SRIXE, and trace amounts of zinc and iron were detected. Mutation of the zinc-coordinating residues in the cysteine-rich motif of poliovirus protein 2C resulted in the loss of the zinc-binding ability. Relative quantities of metal …
Giant Fossil Coelacanths From The Late Cretaceous Of The Eastern Usa, David R. Schwimmer
Giant Fossil Coelacanths From The Late Cretaceous Of The Eastern Usa, David R. Schwimmer
Faculty Bibliography
No abstract provided.
Organic Wheat : A Production Guide, Steven Mccoy
Organic Wheat : A Production Guide, Steven Mccoy
Bulletins 4000 -
Many people believe that organic agriculture systems can only work in high rainfall regions. However, some of Australia’s most successful organic farmers are the experienced organic wheatbelt growers who produce cereal, pulse and oilseed crops in different regions and soil types across the country.
Wheat is the major organic cereal crop grown in Australia - predominantly noodle and breadmaking wheats for export markets.
Farming systems developed by modern organic wheat growers can differ significantly in concept, strategies and techniques from those used by conventional growers. Successful conversion to organic requires careful planning and integration of the whole farming system over …
A New Megalonychid Sloth From The Late Wisconsinan Of The Dominican Republic, Elizabeth Rega, Donald A. Mcfarlane, Joyce Lundberg, Keith Christenson
A New Megalonychid Sloth From The Late Wisconsinan Of The Dominican Republic, Elizabeth Rega, Donald A. Mcfarlane, Joyce Lundberg, Keith Christenson
WM Keck Science Faculty Papers
An unusually well preserved skull, mandible, and indisputably associated post-cranial elements of new sloth, Acratocnus (Miocnus), were recovered from a cave in Jaragua National Park, Dominican Republic. The animal died lying in a rimstone pool and was rapidly coated with a thin calcite patina. We have documented a late Wisconsinan age for this specimen by inorganic 14C radiometric dating of the patina, with supporting data on the carbon systematics of the speleothems in this cave. This sloth is described as a new species on the basis of the distinctive morphology and relative size of cranial and mandibular features. We consider …
A Middle Pleistocene Age And Biogeography For The Extinct Rodent Megalomys Curazensis From Curaçao, Netherlands Antilles, Donald A. Mcfarlane, Joyce Lundberg
A Middle Pleistocene Age And Biogeography For The Extinct Rodent Megalomys Curazensis From Curaçao, Netherlands Antilles, Donald A. Mcfarlane, Joyce Lundberg
WM Keck Science Faculty Papers
The extinct oryzomyine rodent Megalomys curazensis has been known from abundant but fragmentary remains on the island of Curaçao since 1959. Here we demonstrate an age of 130 000 to 400 000 years before present based on geomorphological context, and propose a biogeographical model for the genus.
Soil Leachate Responses During 10 Years Of Induced Whole-Watershed Acidification, Pamela J. Edwards, James N. Kochenderfer, Dean W. Coble, Mary Beth Adams
Soil Leachate Responses During 10 Years Of Induced Whole-Watershed Acidification, Pamela J. Edwards, James N. Kochenderfer, Dean W. Coble, Mary Beth Adams
Faculty Publications
Soil solution was collected from zero-tension lysimeters for 10 yr on two small central Appalachian watersheds in West Virginia, U.S.A. Ammonium sulfate fertilizer was applied to one catchment 3 times per year during each year. The other watershed was used as a reference to account for ambient baseline conditions. Ca and Mg concentrations collected below the A- and B-horizons of the treated watershed increased and then decreased over time as a result of the treatment. By contrast, Ca and Mg concentrations in the C-horizon continued to increase throughout the study period.
Holocene Multidecadal And Multicentennial Droughts Affecting Northern California And Nevada, Larry Benson, Michaele Kashgarian, Robert Rye, Steve Lund, Fred Paillet, Joseph Smoot, Cynthia Kester, Scott Mensing, Dave Meko, Susan Landström
Holocene Multidecadal And Multicentennial Droughts Affecting Northern California And Nevada, Larry Benson, Michaele Kashgarian, Robert Rye, Steve Lund, Fred Paillet, Joseph Smoot, Cynthia Kester, Scott Mensing, Dave Meko, Susan Landström
United States Geological Survey: Staff Publications
Continuous, high-resolution δ18O records from cored sediments of Pyramid Lake, Nevada, indicate that oscillations in the hydrologic balance occurred, on average, about every 150 years (yr) during the past 7630 calendar years (cal yr). The records are not stationary; during the past 2740 yr, drought durations ranged from 20 to 100 yr and intervals between droughts ranged from 80 to 230 yr. Comparison of tree-ring-based reconstructions of climate change for the past 1200 yr from the Sierra Nevada and the El Malpais region of northwest New Mexico indicates that severe droughts associated with Anasazi withdrawal from Chaco Canyon …
Passing The Torch Of Wildlife And Fisheries Management: Comparing The Attitudes And Values Of Younger And Older Conservation Professionals, Robert M. Muth, Rodney R. Zwick, Martha E. Mather, John F. Organ
Passing The Torch Of Wildlife And Fisheries Management: Comparing The Attitudes And Values Of Younger And Older Conservation Professionals, Robert M. Muth, Rodney R. Zwick, Martha E. Mather, John F. Organ
United States Geological Survey: Staff Publications
Wildlife-related values in American society are undergoing considerable change. Within the last few decades, non-consumptive recreational use of wildlife has increased dramatically; groups that subscribe to animal protection values (ranging from animal welfare to animal rights to animal liberation) are exercising increasing influence over wildlife policy, and the ranks of people who practice wildlife rehabilitation have grown significantly. In this time of questioning and change, it should not be surprising that the attitudes and values of conservation professionals are in transition as well. Within many agencies and academic institutions, the traditional focus on game management (Geist et al. 2001) is …
Nitrate Anomaly In The Upper Nutricline In The Northern South China Sea - Evidence For Nitrogen Fixation, George T. F. Wong, Shi-Wei Chung, Fuh-Kwo Shiah, Chung-Chi Chen, Liang-Saw Wen, Kon-Kee Liu
Nitrate Anomaly In The Upper Nutricline In The Northern South China Sea - Evidence For Nitrogen Fixation, George T. F. Wong, Shi-Wei Chung, Fuh-Kwo Shiah, Chung-Chi Chen, Liang-Saw Wen, Kon-Kee Liu
OES Faculty Publications
[1] Up to 2 μM of nitrate anomaly, N*, were found in the upper nutricline at the South East Asia Time-series Study (SEATS) site in the northern South China Sea (SCS). These concentrations were among the higher values reported in the Pacific and indicate the significant contribution of the remineralization of nitrogen-rich organic matter formed by nitrogen fixation to the nutrient dynamics of the area. The concentrations were systematically higher, by up to 2.5 μM, in the Fall through the early Spring, during the northeast monsoon, than in the Summer, suggesting that the impact of nitrogen fixation was higher during …
Arctic Ice Export Events And Their Potential Impact On Global Climate During The Late Pleistocene, Dennis A. Darby, Jens F. Bischof, Robert F. Spielhagen, Steven A. Marshall, Stephen W. Herman
Arctic Ice Export Events And Their Potential Impact On Global Climate During The Late Pleistocene, Dennis A. Darby, Jens F. Bischof, Robert F. Spielhagen, Steven A. Marshall, Stephen W. Herman
OES Faculty Publications
Ice sheets in the North American Arctic and, to a lesser extent, those in northern Eurasia calved large quantities of icebergs that drifted through Fram Strait into the Greenland Sea several times during the late Pleistocene. These icebergs deposited Fe oxide grains (45-250 mum) and coarse lithic clasts >250 mum matched to specific circum-Arctic sources. Four massive Arctic iceberg export events are identified from the Laurentide and the Innuitian ice sheets, between 14 and 34 ka (calendar years) in a sediment core from Fram Strait. These relatively short duration (<1-4 kyr) events contain 3-5 times the background levels of Fe oxide grains. They began suddenly, as indicated by a steep rise in the number of grains matched to an ice sheet source, suggesting rapid purges of ice through Fram Strait, due perhaps to collapse of ice sheets. The larger events from the northwestern Laurentide ice sheet are preceded by events from the Innuitian ice sheet. Despite the chronological uncertainties, the Arctic export events appear to occur prior to Heinrich events.
Progress On Geoenvironmental Models For Selected Mineral Deposit Types, Robert R. Seal Ii, Nora K. Foley
Progress On Geoenvironmental Models For Selected Mineral Deposit Types, Robert R. Seal Ii, Nora K. Foley
United States Geological Survey: Publications
Since the beginning of economic geology as a subdiscipline of the geological sciences, economic geologists have tended to classify mineral deposits on the basis of geological, mineralogical, and geochemical criteria, in efforts to systematize our understanding of mineral deposits as an aid to exploration. These efforts have lead to classifications based on commodity, geologic setting (Cox and Singer, 1986), inferred temperatures and pressures of ore formation (Lindgren, 1933), and genetic setting (Park and MacDiarmid, 1975; Jensen and Bateman, 1979). None of these classification schemes is mutually exclusive; instead, there is considerable overlap among all of these classifications. A natural outcome …
Assessment Of Elemental Concentrations In Streams Of The New Lead Belt In Southeastern Missouri, 2002–05, William G. Brumbaugh, Thomas W. May, John M. Besser, Ann L. Allert, Christopher J. Schmitt
Assessment Of Elemental Concentrations In Streams Of The New Lead Belt In Southeastern Missouri, 2002–05, William G. Brumbaugh, Thomas W. May, John M. Besser, Ann L. Allert, Christopher J. Schmitt
United States Geological Survey: Publications
Concerns about possible effects of lead-mining activities on the water quality of federally protected streams located in southeastern Missouri prompted a suite of multidisciplinary studies to be conducted by the U.S. Geological Survey. As part of this investigation, a series of biological studies were initiated in 2001 for streams in the current mining region and the prospecting area. In this report, results are examined for trace elements and other selected chemical measurements in sediment, surface water, and sediment interstitial (pore) water sampled between 2002 and 2005 in association with these biological studies. Compared to reference sites, fine sediments collected downstream …
Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt
Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt
United States Geological Survey: Staff Publications
µ≤≥
Fish were collected in late 1995 from 34 National Contaminant Biomonitoring Program (NCBP) stations and 13 National Water Quality Assessment Program (NAWQA) stations in the Mississippi River basin (MRB) and in late 1996 from a reference site in West Virginia. Four composite samples, each comprising (nominally) 10 adult common carp (Cyprinus carpio) or black bass (Micropterus spp.) of the same sex, were collected from each site and analyzed for organochlorine chemical residues by gas chromatography with electron capture detection. At the NCBP stations, which are located on relatively large rivers, concentrations of organochlorine chemical residues were generally lower than …
Reconstruction Of Hydrological Changes And Response To Effective Moisture Variations From North-Central Usa Lake Sediments, Antje Schwalb, Walter E. Dean
Reconstruction Of Hydrological Changes And Response To Effective Moisture Variations From North-Central Usa Lake Sediments, Antje Schwalb, Walter E. Dean
United States Geological Survey: Staff Publications
Ratios of the stable isotopes of oxygen and carbon in benthic ostracodes and marl from cores taken from two lakes in north-central Minnesota reflect Holocene hydrological and vegetation changes. Oxygen isotopes show that Williams and Shingobee Lakes, located in the same watershed but with different positions along a hydrologic gradient, were connected before 9.8 ka as part of a larger lake, Lake Willobee. From 9.8–7.7 ka, the level of Lake Willobee fell as a result of glacial retreat and increasing evaporation, leaving small separated basins. Further decreases in lake level after 7.7 ka due to increasing aridity triggered the inflow …
Crustal Fissuring On The Crest Of The Southern East Pacific Rise At 17˚15'-40'S, Dawn J. Wright, Rachel M. Haymon, Scott M. White, Ken C. Macdonald
Crustal Fissuring On The Crest Of The Southern East Pacific Rise At 17˚15'-40'S, Dawn J. Wright, Rachel M. Haymon, Scott M. White, Ken C. Macdonald
Faculty Publications
Fissure densities and widths have been mapped along the axial zone of the superfast spreading southern East Pacific Rise (EPR) at 17_150–400S with the near-bottom DSL-120 and Argo II imaging systems. We observe that the youngest lava flows (on a relative age scale) are sparsely fissured and that there is a cumulative increase in fissure abundance with time that produces a strong positive correlation between fissure density and relative age of lava flows. Average fissure widths were used to estimate fissure depths. In the 17_150–400S area, calculated fissure depths are estimated to extend below the seismic layer 2A/2B boundary, and …
Stable Isotopes Of Carbon As An Invaluable Stratigraphic Tool: An Example From The Cambrian Of The Northern Appalachians, Usa, Bosiljka Glumac, Malkah L. Spivak-Birndorf
Stable Isotopes Of Carbon As An Invaluable Stratigraphic Tool: An Example From The Cambrian Of The Northern Appalachians, Usa, Bosiljka Glumac, Malkah L. Spivak-Birndorf
Geosciences: Faculty Publications
This study illustrates the usefulness of carbon isotopes in stratigraphic interpretations of poorly fossiliferous strata beyond the resolution possible by biostratigraphy. The Upper Cambrian strata of the lower Gorge Formation in northwestern Vermont have been interpreted as highly condensed continental-slope deposits with a hiatus bracketed by the trilobite fauna of the Dunderbergia zone (Steptoean) and the Saukia zone (upper Sunwaptan). This interpretation was based on information from two thin fossiliferous intervals, the occurrence of one of them being unconfirmed in a recent study. Carbon isotopes provide a means for testing this interpretation because marine carbonate rocks deposited during the Steptoean …
In Situ Hydraulic Testing And Water Quality Sampling In The Hyporheic Zone Of The Columbia River, Hanford Reach, Washington, Evan V. Arntzen
In Situ Hydraulic Testing And Water Quality Sampling In The Hyporheic Zone Of The Columbia River, Hanford Reach, Washington, Evan V. Arntzen
Dissertations and Theses
Several chemical and radiological contaminants are present in an unconfined aquifer underlying the U.S. Department of Energy's Hanford Site in southeast Washington State. Hexavalent chromium [Cr(VI)], previously used as an anticorrosive in plutonium production reactors on the shoreline of the Columbia River, is of particular concern because of its conservative nature, toxicity to humans and aquatic life, and proximity to protected salmon spawning habitat. Hydrogeologic data are abundant from the unconfined aquifer, but are lacking from the hyporheic zone through which Cr(VI) is transported into the river. A hydrogeologic study was conducted near one known Cr(VI) plume to determine the …
Relating Net Nitrogen Input In The Mississippi River Basin To Nitrate Flux In The Lower Mississippi River: A Comparison Of Approaches, Gregory F. Mcisaac, Mark B. David, George Z. Gertner, Donald A. Goolsby
Relating Net Nitrogen Input In The Mississippi River Basin To Nitrate Flux In The Lower Mississippi River: A Comparison Of Approaches, Gregory F. Mcisaac, Mark B. David, George Z. Gertner, Donald A. Goolsby
United States Geological Survey: Staff Publications
A quantitative understanding of the relationship between terrestrial N inputs and riverine N flux can help guide conservation, policy, and adaptive management efforts aimed at preserving or restoring water quality. The objective of this study was to compare recently published approaches for relating terrestrial N inputs to the Mississippi River basin (MRB) with measured nitrate flux in the lower Mississippi River. Nitrogen inputs to and outputs from the MRB (1951 to 1996) were estimated from state-level annual agricultural production statistics and NOy (inorganic oxides of N) deposition estimates for 20 states that comprise 90% of the MRB. A model …
Early Holocene Change In Atmospheric Circulation In The Northern Great Plains: An Upstreamview Of The 8.2 Ka Cold Event, Walter E. Dean, Richard M. Forester, J. Platt Bradbury
Early Holocene Change In Atmospheric Circulation In The Northern Great Plains: An Upstreamview Of The 8.2 Ka Cold Event, Walter E. Dean, Richard M. Forester, J. Platt Bradbury
United States Geological Survey: Staff Publications
Elk Lake, in northwestern Minnesota, contains numerous proxy records of climatic and environmental change contained in varved sediments with annual resolution for the last 10,000 years. These proxies show that about 8200 calendar years ago (8.2 cal. ka; 7300 radiocarbon years) Elk Lake went froma well-stratified lake that was wind-protected in a boreal forest to a well-mixed lake in open prairie savanna receiving northwesterly wind-blown dust, probably from the dry floor of Lake Agassiz. This change in climate marks the initiation of the widely recognized mid-Holocene “altithermal” in central North America. The coincidence of this change with the so-called 8.2 …
Modeling The Biogeochemical Cycle Of Selenium In The San Francisco Bay, Shannon L. Meseck
Modeling The Biogeochemical Cycle Of Selenium In The San Francisco Bay, Shannon L. Meseck
OES Theses and Dissertations
Due to recent concerns about selenium toxicity in the San Francisco Bay and the roles of refinery and San Joaquin River inputs on the selenium cycle, the model ECoS 3 (distributed from Plymouth Marine Laboratory, United Kingdom) was modified to simulate the biogeochemical cycle of selenium in the Northern Reach. The model is designed to simulate salinity, total suspended material, phytoplankton concentrations, dissolved selenium and its speciation (selenite, selenate, and organic selenide), and particulate selenium and its speciation (selenite + selenate, elemental selenium, and organic selenide). Actual data from 1999 were used to calibrate the model, while data from other …
Barium And Lithium In Foraminifera: Glacial-Interglacial Changes In The North Atlantic, Jenney M. Hall
Barium And Lithium In Foraminifera: Glacial-Interglacial Changes In The North Atlantic, Jenney M. Hall
LSU Doctoral Dissertations
The trace element content of calcareous foraminifera provides a powerful tool to the study of glacial-interglacial changes in the physical and chemical properties of the ocean. Foraminifera incorporate barium in direct proportion to its concentration in seawater. Using barium as a nutrient proxy, Ba/Ca in benthic Planulina wuellerstorfi is used to reconstruct changes in thermocline ventilation and mid-depth circulation in the North Atlantic during the last glacial and deglacial time. Rivers are concentrated in barium compared to surface seawater. Therefore, barium in planktonic Neogloboquadrina pachyderma is used to identify deglacial meltwater in the Arctic Ocean. Foraminiferal Li/Ca was analyzed to …
The Meeting Of Two Microbial Worlds: Geochemistry Of The Sulfate-Methane Interface, Walter S. Borowski, Charles K. Paull, William Ussler Iii
The Meeting Of Two Microbial Worlds: Geochemistry Of The Sulfate-Methane Interface, Walter S. Borowski, Charles K. Paull, William Ussler Iii
EKU Faculty and Staff Scholarship
No abstract provided.
Intra-Annual Variation In The Stable Oxygen And Carbon And Trace Element Composition Of Sclerosponges, P. K. Swart, S. Thorrold, B. Rosenheim, A. Eisenhauer, C. G. A. Harriason, M. Grammer, C. Latkoczy
Intra-Annual Variation In The Stable Oxygen And Carbon And Trace Element Composition Of Sclerosponges, P. K. Swart, S. Thorrold, B. Rosenheim, A. Eisenhauer, C. G. A. Harriason, M. Grammer, C. Latkoczy
Biological Sciences Faculty Publications
This paper presents data to support the presence of (1) intra-annual signals in the chemical composition (δ18O and Sr/Ca) of the skeletons ofsclerosponges from the Bahamas and (2) variable rates of skeletal accretion. These conclusions are based on data obtained by using a microsampling method for the stable oxygen and carbon isotopes in which material was extracted at a resolution of one sample every 34 μm and a laser microprobe which obtained trace element data every 20 μm (Sr, Mg, and Pb). An age model was established using a combination of changes in the concentration of Pb, the …