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Articles 961 - 990 of 1124
Full-Text Articles in Earth Sciences
Mapping The Nonstationary Internal Tide With Satellite Altimetry, Edward Zaron
Mapping The Nonstationary Internal Tide With Satellite Altimetry, Edward Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
t Temporal variability of the internal tide has been inferred from the 23 year long combined records of the TOPEX/Poseidon, Jason-1, and Jason-2 satellite altimeters by combining harmonic analysis with an analysis of along-track wavenumber spectra of sea-surface height (SSH). Conventional harmonic analysis is first applied to estimate and remove the stationary components of the tide at each point along the reference ground tracks. The wavenumber spectrum of the residual SSH is then computed, and the variance in a neighborhood around the wavenumber of the mode-1 baroclinic M2 tide is interpreted as the sum of noise, broadband nontidal processes, and …
A Comparison Of Benthic Macroinvertebrate Assemblages Between Perennial And Intermittent Headwater Streams Of The Mattole River In Northern California, Usa, Mason S. London
Cal Poly Humboldt theses and projects
Intermittent streams are common throughout the world and comprise 60% or more of total river lengths in the conterminous United States. Despite their prevalence, intermittent streams are understudied, particularly first-order headwater streams, which are vital for maintaining the function, health and biotic diversity of river networks. In June 2016, I sampled five intermittent and five perennial headwater streams in the Mattole River watershed in northwestern coastal California, USA, to compare benthic macroinvertebrate (BMI) assemblages between intermittent and perennial streams. BMI samples were collected using a 500µm mesh D-net at eight randomly located riffles along a 150-m reach, and then composited, …
Paleoecology Of Foraminifera From The Late Miocene - Early Pliocene Pullen And Saint George Formations, Northwestern California, Trenton J. Ryan
Paleoecology Of Foraminifera From The Late Miocene - Early Pliocene Pullen And Saint George Formations, Northwestern California, Trenton J. Ryan
Cal Poly Humboldt theses and projects
The Pullen and Saint George formations are coeval late Miocene-early Pliocene sedimentary formations in northwestern California. The type localities of both formations were studied from a micropaleontologic perspective that focused primarily on Foraminifera, but with additional observations of other fossil groups to reconstruct their past depositional environments. The results obtained in this study provided a photomicrographic inventory of the microfossils from both formations, aided in investigating changes in paleobathymetry of the formations during the late Miocene and early Pliocene based on Foraminifera, and allowed for interpretation of paleoecological signals from the foraminiferan associations. Foraminifera have not been previously described in …
Spatial Variability Of The Depth To The Magma Reservoir Beneath The Yellowstone Caldera Inferred From Observations Of Seiche Loading Induced Strain, Kevin James Gryger
Spatial Variability Of The Depth To The Magma Reservoir Beneath The Yellowstone Caldera Inferred From Observations Of Seiche Loading Induced Strain, Kevin James Gryger
LSU Master's Theses
Seiche waves in Yellowstone Lake at ~78, ~51, and ~25 minute periods and heights <10 cm can cause measurable strain (< 40 ns) as observed on borehole strainmeters both near (<300 m) and far (~20 km) from the lake. Observations of the correlation between the seiche waves and the associated strain response can be used to constrain the rigidity of the upper crust, the depth to magma bodies in the subsurface, and the viscosity (related to melt percentage) of the magma bodies in place. Lake level was directly measured with campaign absolute pressure gauges deployed in the West Thumb basin, Breeze Channel, and central basin of Yellowstone Lake, and 13 large seiche events (¡Ý7 cm) were identified from these observations. Periodic strain transients were measured on borehole strainmeters in the caldera during the 13 large seiche events. The peak-to-trough amplitude and phase of the seiche wave and strain response were estimated by fitting a multi-frequency sinusoid to the time series over a 4-hour window during each seiche event. It was found that the relationship between an applied seiche load and the associated strain response is self-consistent and linearly proportional at each borehole strainmeter in the caldera. Over multiple seiche events the observed strain response is consistent with a modeled strain-field produced by a seiche load on a two-layered viscoelastic model defined by free parameters Young¡¯s modulus (E1), plate thickness (H), and shear modulus ratio (¦Ì2/¦Ì1). The two-layered viscoelastic model represents a solid upper crust overlying a partially molten body which may be small pockets of melt (<1 km thickness) or a larger magma reservoir. Results suggest crystallizing melt beneath Yellowstone caldera at depths (H) of ~4¨C8 km in the south-southeast and ~3-5 km in the north-northwest sections of the caldera. Temporal observations between strain meters, coupled with constraints of Young¡¯s and shear moduli suggest that melt in the shallow crust has a viscosity ¡Ü1013 Pa s.
Microseismic Event Characteristics Associated With The Spatial And Temporal Stages Of Hydraulic Fracture Growth In Laboratory Experiments, Abigail Arielle Maxwell
Microseismic Event Characteristics Associated With The Spatial And Temporal Stages Of Hydraulic Fracture Growth In Laboratory Experiments, Abigail Arielle Maxwell
LSU Master's Theses
There are uncertainties in the exact mechanisms that occur during hydraulic fracture growth and the interactions of hydraulic fractures with pre-existing fractures. In some cases fracture growth is seen to be purely tensile and in others a combination of tensile and shear mechanisms. In order to develop a seismic model to explain fracture propagation, there is a need for a complete classification of the microseismic events occurring during fracturing using waveform characteristics such as frequency, duration and magnitude. This classification would allow for more accurate prediction of the behavior of the hydraulic fracture from its initiation to when it intersects …
Palynostratigraphy And Environmental Implication Of Organic-Walled Microfossils Recovered From Iodp Site U1435, Mitchell Clifford Gregory
Palynostratigraphy And Environmental Implication Of Organic-Walled Microfossils Recovered From Iodp Site U1435, Mitchell Clifford Gregory
LSU Master's Theses
Extensive studies have examined the syn- and post-rift sediments in the South China Sea and surrounding margins, but pre-rift, Eocene deposits are rare. Here we examine organic-walled microfossils from the South China Sea, recovered at Site U1435 of IODP Expedition 349 to provide palynostratigraphic control and characterize the environmental setting before, and in response to, the initiation of seafloor spreading in the basin ~33 Ma. The well preserved palynological assemblage recovered allow dating of sediments sampled at Site U1435. Units II and III are now subdivided in 4 subzones; Zone 1 is essentially barren, Zones 2 and 3A are assigned …
Shallow Shear-Wave Seismic Analysis Of Point Bar Deposits Of False River, Louisiana, Martial James Morrison
Shallow Shear-Wave Seismic Analysis Of Point Bar Deposits Of False River, Louisiana, Martial James Morrison
LSU Master's Theses
Current point-bar complex models do not include subsurface unit bars as a normal feature. This study provides evidence for a potential buried unit bar amongst point-bar sediments of the large-scale, modern-day False River point-bar complex of the Mississippi River. We collect, process and interpret a two-dimensional, 150-m-long CMP seismic reflection profile that cuts perpendicularly across a major discontinuity surface in the False River point bar complex. The seismic source consists of a ground recoil device that fires a shotgun shell horizontally, producing shear waves. Multiple field experiments demonstrated which type of source and receiver provided the least amount of noise, …
Sediment Infilling Of Louisiana Continental-Shelf Dredge Pits: A Record Of Sedimentary Processes In The Northern Gulf Of Mexico, Meg Cathlin O'Connor
Sediment Infilling Of Louisiana Continental-Shelf Dredge Pits: A Record Of Sedimentary Processes In The Northern Gulf Of Mexico, Meg Cathlin O'Connor
LSU Master's Theses
Sediment cores were collected at continental-shelf sites of the Northern Gulf of Mexico off the coast of Louisiana to develop a better understanding of post-dredging evolution of mud-capped dredge pits. The two pits studied were Sandy Point (SP) and Raccoon Island (RI) (both with water depths of ~10m and dredged to ~ 15-20 m below water surface), which were dredged in 2012 and 2013 respectively. Vibracores and multicores were collected in 2015. Preliminary radiochemistry analyses identified Beryllium-7 distribution in multicore samples from both sites. SP1, the northwestern site in the Sandy Point dredge pit, showed 26 cm of 7Be penetration. …
The Relationship Between The Timing Of Hydrocarbon Generation Between The Bristol Bay Depositional Basin And The Port Moller Area And Southern Portion Of The Bristol Bay Basin Of The Alaska Peninsula, Claire Rochelle Jones
The Relationship Between The Timing Of Hydrocarbon Generation Between The Bristol Bay Depositional Basin And The Port Moller Area And Southern Portion Of The Bristol Bay Basin Of The Alaska Peninsula, Claire Rochelle Jones
LSU Master's Theses
The Alaska Peninsula has been the target of oil and gas exploration throughout much of the 20th century. Although most exploration efforts have focused on the Cook Inlet area, the geological setting of the Alaskan Peninsula suggests that economically viable resources may be located further south on the northern side bordering Bristol Bay (Port Moller area). This study investigates the relation of petroleum system elements between the northern and southern section of the Alaskan Peninsula with a particular focus on the potential for petroleum accumulation on the southern section close to Herendeen Bay. The analysis included the integration of a …
Modelling And Observational Evidence For The Igneous Evolution Of The Elysium Volcanic Province On Mars, David Andrew Susko
Modelling And Observational Evidence For The Igneous Evolution Of The Elysium Volcanic Province On Mars, David Andrew Susko
LSU Master's Theses
A major knowledge gap exists on how eruptive compositions of a single martian volcanic province change over time. The Elysium Volcanic Province is a location of great geologic interest on Mars. Its predominantly Amazonian surface age (beginning 3.3 Ga), and its isolation in the northern hemisphere of Mars away from other volcano-tectonic regions, make it an ideal locale to investigate igneous compositions erupted during the most recent geologic period on Mars. Here, this work seeks to fill that gap by assessing the compositional evolution of Elysium as a major martian volcanic province in two related projects. The first project seeks …
In Search Of Antarctica's Last Vegetation Refugium Within The Mcmurdo Dry Valleys, David Rau
In Search Of Antarctica's Last Vegetation Refugium Within The Mcmurdo Dry Valleys, David Rau
LSU Master's Theses
The McMurdo Dry Valleys, a hyper-arid cold polar desert located within the Transantarctic Mountains was once covered by vegetation. An in depth study of surface samples of various Neogene age, acquired throughout the Valleys, provide insight to the location of one of Antarctica’s last vegetation refugia. Boston University’s Antarctic Research Group has collected 82 surface samples from paleo lake sediments on 14 expeditions spanning 22 years in the McMurdo Dry Valleys. The ages of the samples are still not fully constrained, but 8 regions where samples were collected have been interpreted to range between 16.95 ± 0.17 to 4 Ma …
Upper Water Structure And Mixed Layer Depth In Tropical Waters: The Seats Station In The Northern South China Sea, Jen-Hua Tai, George T. F. Wong, Xiaoju Pan
Upper Water Structure And Mixed Layer Depth In Tropical Waters: The Seats Station In The Northern South China Sea, Jen-Hua Tai, George T. F. Wong, Xiaoju Pan
OES Faculty Publications
The variability of the upper water hydrographic structure, the efficacy of the different schemes for estimating the mixed layer depth (MLD), the inter-comparability estimation of the MLDs and diurnal and intra-annual MLD climatology in the tropical waters in the northern South China Sea were accessed in 702 depth-profiles of potential temperature (θ) and salinity collected in 64 cruises between 17.5 and 18.5°N and 115.3 and 116.3°E from 1997 to 2013. The hydrographic structure may be subdivided into three principal types: the classical type, with quasi-isopycnal surface mixed layer followed by an abrupt increase in the depth-gradient in θ and potential …
Holocene Cyclic Records Of Ice-Rafted Debris And Sea Ice Variations On The East Greenland And Northwest Iceland Margins, D. A. Darby, J. T. Andrews, S. T. Belt, A. E. Jennings, P. Cabedo-Sanz
Holocene Cyclic Records Of Ice-Rafted Debris And Sea Ice Variations On The East Greenland And Northwest Iceland Margins, D. A. Darby, J. T. Andrews, S. T. Belt, A. E. Jennings, P. Cabedo-Sanz
OES Faculty Publications
The dynamics of the Greenland Ice Sheet and drift of sea ice from the Arctic Ocean reaching Denmark Strait are poorly constrained. We present data on the provenance of Fe oxide detrital grains from two cores in the Denmark Strait area and compare the Fe grain source data with other environmental proxies in order to document the variations and potential periodicities in ice-rafted debris delivery during the Holocene. Based on their Fe grain geochemistry, the sediments can be traced to East Greenland sources and to more distal sites around the Arctic Basin. On the Holocene time scales of the two …
Using Thermal Infrared Imagery To Estimate Soil Hydraulic Parameters: A Novel Approach, Matthew B. Thomas
Using Thermal Infrared Imagery To Estimate Soil Hydraulic Parameters: A Novel Approach, Matthew B. Thomas
Undergraduate Theses, Professional Papers, and Capstone Artifacts
In this study, skin temperature measured with a thermal infrared (TIR) camera was used to estimate soil hydraulic parameters. These physical properties that control how soils transport and retain water are notoriously difficult to measure in the field due to spatial variability. Laboratory experiments were set up to record surface skin temperature response in a clean soil column using a TIR camera after an artificial wetting event. An array of thermocouples, a net radiometer, heat flux sensor and weather station were used to constrain the TIR data and the energy budget during the experiment. The soil column surface was then …
Geoarchaeology Of Ancient Site Settlement At Eastern Thungkula Ronghai, Srisaket And Yasothon Provinces In Northeast Thailand, Patcharaporn Ngernkerd
Geoarchaeology Of Ancient Site Settlement At Eastern Thungkula Ronghai, Srisaket And Yasothon Provinces In Northeast Thailand, Patcharaporn Ngernkerd
Chulalongkorn University Theses and Dissertations (Chula ETD)
Archaeology in Thailand is generally associated with geological application. In this work, the relationship between ancient site settlement and geomorphology is carried out under geoarchaeological approach. Study area is located on the eastern Thungkula Ronghai (TKR) bordered between Mun and Chi Rivers in Srisaket and Yasothon where many archaeological sites have been found. The research focuses on aerial photograph and satellite imaginary interpretation, application of ground penetrating radar (GPR) on sand splays morphology and GIS software to analyze ancient site location on geomorphology for reconstructing the relationship of human past with their landscapes. Results indicate the interesting landforms of the …
A Palynostratigraphic Investigation Of Holocene Coastal Texas Bays: Implications For Future Coastal Change, Shannon Marie Ferguson
A Palynostratigraphic Investigation Of Holocene Coastal Texas Bays: Implications For Future Coastal Change, Shannon Marie Ferguson
LSU Doctoral Dissertations
Although the Gulf of Mexico is one of the most studied basins in the world, a majority of the focus has been driven by petroleum exploration and/or on seismic and sedimentological facies models. Rarely has the intent of previous studies been to characterize the Holocene climatic record of coastal Texas. Of those studies that discuss Holocene vegetation change, the majority focus on the Mississippi River Delta, the Edwards Plateau or central Florida, leaving an absence of insight to western Gulf of Mexico climate changes. The Texas coastline stretches 595 km across almost 4° of latitude and the strong northwestern precipitation …
Quaternary River Erosion, Provenance, And Climate Variability In The Nw Himalaya And Vietnam, Tara Nicole Jonell
Quaternary River Erosion, Provenance, And Climate Variability In The Nw Himalaya And Vietnam, Tara Nicole Jonell
LSU Doctoral Dissertations
The influence of Quaternary climate variation on sediment generation, storage, and transport in two mountainous Asian river basin was examined in the largest tributary to the upper Indus River in the Himalayan rain shadow, the Zanskar River basin (~15,000 km2), and the smaller, subtropical Song Gianh basin (<3,500 km2) of central Vietnam. Spatial patterns of erosion in the Zanskar River Basin were established to quantify the dominant controls on Quaternary sedimentation in the Himalayan rain shadow on the edge of the Tibetan Plateau. Glacial erosion and precipitation along the High Himalaya together dominate sediment production and transport …3,500>
Analysis Of Microbial Diversity In Disturbed Soil, Tyler G. Sanda
Analysis Of Microbial Diversity In Disturbed Soil, Tyler G. Sanda
Williams Honors College, Honors Research Projects
This paper uses the composition and abundance of microbial species to analyze soil recovery in disturbed land. Surface mining disturbs ecological communities throughout the world. As organizations seek to reclaim these disturbed lands, a proper analysis of recovery is needed. In previous studies, recovery of disturbed land was limited to surface examinations, which do not characterize the possible unseen devastating effects of the subsoil. Soil microorganisms are extremely sensitive to environmental changes such as strip mining. It is proposed that these microorganisms may serve as better indicators of recovery post disturbance. Our analysis indicates microbial recovery, however it may not …
Pressure Dependence Of Polycrystalline Magnesite And Dolomite, Cole Blasko
Pressure Dependence Of Polycrystalline Magnesite And Dolomite, Cole Blasko
Williams Honors College, Honors Research Projects
Intermediate depth (170-400 km) deep focus earthquakes are observed in subducting slabs, but unlike shallow (50-170 km) and deep (400-660 km) deep focus earthquakes, the mechanism(s) responsible for them are not clear. Two common alteration products observed in peridotites, magnesite and dolomite, are stable along the pressure-temperature path of a subducting slab. Low pressure experiments indicate that these minerals are weaker than olivine, but there are no data about the pressure dependence of the strength of magnesite or dolomite. Magnesite and dolomite cylinders (1mm by 1mm) were deformed in stacked series to 25-30% strain using the deformation-DIA (DDIA) at Argonne …
Mercury Increases In Lake Tanganyika Since ~1850, Troy A. Bole
Mercury Increases In Lake Tanganyika Since ~1850, Troy A. Bole
Williams Honors College, Honors Research Projects
A series of three sediment cores were collected in Lake Tanganyika, Africa, and were analyzed for mercury concentrations. For all three cores, a decrease in mercury (Hg) levels was observed from the 1600’s (appx. 20 ng/g) until concentrations reached a minimum during the mid-1800’s (appx. 10 ng/g). The mid-1800’s marked a change from decreasing mercury levels to an increase over the following century. The core tops (circa 2006) have concentrations greater than 70 ng/g. The onset of the rise in mercury concentrations coincides with the beginning of the Industrial Revolution in the mid to late 18th century. Relationships between …
Structural Basis Of Membrane Protein Scaffolding And Signaling In Human Disease, Joshua Holcomb
Structural Basis Of Membrane Protein Scaffolding And Signaling In Human Disease, Joshua Holcomb
Wayne State University Dissertations
Protein structural elucidation by means of X-ray crystallography is a powerful approach for both insight into a proteins biophysical properties and function. To date X-ray crystallography remains the gold standard in high resolution structural determination and serves as the basis for rational drug design for the purpose of combating a number of human diseases. Such an approach also allows for the exploitation of how various proteins interact with their substrates providing a molecular basis for their physiological function. In this dissertation, using X-ray crystallographic analysis along with other biophysical characterization methods, we seek to understand the mechanistic foundation for which …
Carbon Cycle Trends Recorded By Organic Carbon Stable Isotopes In Paleocene Strata, Benton County, Mississippi: Implications For Chronostratigraphy Of The Porters Creek And Naheola Formations, Erica Gerweck
Electronic Theses and Dissertations
The paleocene-eocene thermal maximum (petm) is one of the most studied carbon isotope excursions in earth's history. The petm occurred 55 million years ago when excess isotopically heavy carbon (c13) was added into earth's carbon cycle, resulting in ecological and environmental changes. The petm is marked by a negative stable carbon isotope excursion (cie) in marine and continental strata around the globe. The paleocene and eocene boundary is contained in the sedimentary fill of the Mississippi embayment so there is high potential to produce new petm stable isotope datasets. The purpose of this project is to analyze the boundary for …
Effects Of Sea Level Rise On Hydrology: Case Study In A Typical Mid-Atlantic Coastal Watershed, Xixi Wang, Rui Li, Homa Jalaeian Taghadomi, Shohreh Pedram, Xiao Zhao
Effects Of Sea Level Rise On Hydrology: Case Study In A Typical Mid-Atlantic Coastal Watershed, Xixi Wang, Rui Li, Homa Jalaeian Taghadomi, Shohreh Pedram, Xiao Zhao
Civil & Environmental Engineering Faculty Publications
Sea level rise (SLR) can negatively affect the hydrology of coastal watersheds. However, the relevant information is incomplete and insufficient in existing literature. The objective of this study is to present a modeling approach to predict long-term effects of SLR on changes of flood peak, flood stage, and groundwater table with an assumption that the historical climate would reoccur in the future. The study was conducted for a typical coastal watershed in southeast USA. The results indicate that sea level had been rising at a rate of 4.21 mm yr−1 from 1948 to 1982 but at a faster rate …
Wellbore Stability Evaluation For Mishrif Formation, Ethar H.K. Alkamil, Husam R. Abbood, Ralph E. Flori, Andreas Eckert
Wellbore Stability Evaluation For Mishrif Formation, Ethar H.K. Alkamil, Husam R. Abbood, Ralph E. Flori, Andreas Eckert
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
During drilling operations for the E oilfield in the Mishrif formation in southern Iraq, stuck pipe has been identified as a significant geomechanical problem for several wells. In this study, a 1-D mechanical earth model (MEM) of the Mishrif formation is compiled based on its state of stress and rock strength parameters and is utilized to assess the contribution of borehole collapse leading to the stuck pipe problems. The MEM model is based on the principal in situ stresses and their orientation obtained from wireline logs measurements, measuring while drilling (MWD), and leak off test (LOT). Rock strength properties are …
Phytoforensics: Applications In Vapor Intrusion Assessment, Jordan Lee Wilson
Phytoforensics: Applications In Vapor Intrusion Assessment, Jordan Lee Wilson
Doctoral Dissertations
"Vapor intrusion (VI) occurs when contaminants in the vapor phase migrate in the shallow subsurface and enter buildings through cracks, seams, and gaps and has been recognized as a serious human-health threat as occupants are exposed to potentially harmful concentrations over long periods of time. The VI pathway has recently (2017) been identified as a primary exposure pathway and implemented into the Hazard Ranking System for inclusion on the Nation Priorities List. However, assessing VI and human exposure is not simple and current methods are time-, cost-, and labor-intensive; intrusive; and temporally and spatially variability. Trees are ideal candidates for …
Acquisition Of Active Multichannel Analysis Of Surface Waves (Masw) Data In Karst Terrain, Ghassan Salem Alsulaimani
Acquisition Of Active Multichannel Analysis Of Surface Waves (Masw) Data In Karst Terrain, Ghassan Salem Alsulaimani
Doctoral Dissertations
"This study was designed to verify the effects and data reproducibility when the length of receiver array, receiver spacing, source offset and array orientation parameters are changed for data acquired using multichannel analysis of surface waves (MASW), at intended target depth of 30ft (9m), and to compare the results with electrical resistivity tomography (ERT) data obtained for the same study site.
The MASW data acquired for 34 sites, along four profiles for each site using variable source offsets of 10ft (3m) and 30ft (9.1m), and variable receiver spacings of 2.5ft (0.76m) and 5.0ft (0.76m), concurrently. Out of the 272 profiles …
Isotope Investigation Of Nitrate In Soils And Agricultural Drain Waters Of The Lower Yakima Valley, Washington, Dallin Jensen
Isotope Investigation Of Nitrate In Soils And Agricultural Drain Waters Of The Lower Yakima Valley, Washington, Dallin Jensen
All Master's Theses
Nitrate in the groundwater of the Lower Yakima Valley, Washington has long been known to frequently exceed the EPA maximum contaminant level standard for potable water (10 mg/L), adversely impacting communities with disadvantaged socio-economic status. In this research, nitrogen and oxygen isotopic signatures were determined for nitrate soil leachates and irrigation return flow collected in the Lower Yakima Valley, Washington and compared to previous isotopic studies of nitrate in Central Washington. δ15N, δ18O and Δ17O values are used to constrain sources of to groundwater. Isotope signatures for nitrate from soil leachate largely overlapped with …
Greater Sage-Grouse Resource Selection Drives Reproductive Fitness Under A Conifer Removal Strategy, Charles P. Sandford, Michel T. Kohl, Terry A. Messmer, David K. Dahlgren, Avery Cook, Brian R. Wing
Greater Sage-Grouse Resource Selection Drives Reproductive Fitness Under A Conifer Removal Strategy, Charles P. Sandford, Michel T. Kohl, Terry A. Messmer, David K. Dahlgren, Avery Cook, Brian R. Wing
Wildland Resources Faculty Publications
The link between individual variation in resource selection (e.g., functional response) and fitness creates a foundation for understanding wildlife-habitat relationships. Although many anthropogenic activities adversely affect these relationships, it is largely unknown whether projects implemented to benefit wildlife populations actually achieve this outcome. For sagebrush (Artemisia spp.) obligate species such as the greater sage-grouse (Centrocercus urophasianus; sage-grouse), expansion of juniper (Juniperus spp.) and pinyon-pine (Pinus spp.; conifers) woodlands into sagebrush ecosystems has been identified as a conservation threat. This threat is intensified when a sagebrush ecosystem is bounded by naturally unsuitable habitats. As such, federal, state, …
Great Plains Geology, Robert F. Diffendal Jr.
Great Plains Geology, Robert F. Diffendal Jr.
University of Nebraska Press: Sample Books and Chapters
Great Plains Geology concisely guides readers through the geological development of the Great Plains region. It describes the distinct features of fifty-seven geologic sites, including fascinating places such as Raton Pass in Colorado and New Mexico, the Missouri Breaks of Montana, and the Ashfall Fossil Beds in Nebraska. This guide addresses the tricky question of what constitutes the Great Plains, showing that the region is defined in part through its unique geologic features.
Introducing Global Peat-Specific Temperature And Ph Calibrations Based On Brgdgt Bacterial Lipids, B.D.A. Naafs, G. N. Imglis, Y. Zheng, M. J. Amesbury, H. Biester, R. Bindler, J. Blewett, M. A. Burrows, D. Del Castillo Torres, F. M. Chambers, P. G. Hatcher
Introducing Global Peat-Specific Temperature And Ph Calibrations Based On Brgdgt Bacterial Lipids, B.D.A. Naafs, G. N. Imglis, Y. Zheng, M. J. Amesbury, H. Biester, R. Bindler, J. Blewett, M. A. Burrows, D. Del Castillo Torres, F. M. Chambers, P. G. Hatcher
Chemistry & Biochemistry Faculty Publications
Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (−8 to 27 °C) and pH (3–8) range …