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2019

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Articles 691 - 720 of 1657

Full-Text Articles in Earth Sciences

Stable Isotope And Geochemical Characterization Of Nutrient Sources In The Big Creek Watershed Of Northwest Arkansas, Kelly Robin Sokolosky Aug 2019

Stable Isotope And Geochemical Characterization Of Nutrient Sources In The Big Creek Watershed Of Northwest Arkansas, Kelly Robin Sokolosky

Graduate Theses and Dissertations

The establishment of a concentrated animal-feeding operation (CAFO) in Newton County, Arkansas near Big Creek, a tributary of the Buffalo National River, has raised concern over potential degradation of water-quality in the watershed. In this study, isotopic tools were combined with standard geochemical approaches to characterize nutrient sources and dynamics in Big Creek. An isotopic and geochemical reference library of potential nutrient sources in the Big Creek watershed was established by direct sampling of representative potential sources, including septic-system effluent, poultry litter, swine and cattle manure, and CAFO waste lagoons. Representative nutrient sources and Big Creek stream samples were analyzed …


The Structure And Dynamics Of A River Delta Are Related Through Its Nourishment Area, Suggesting Optimality, Christopher A. Cathcart Aug 2019

The Structure And Dynamics Of A River Delta Are Related Through Its Nourishment Area, Suggesting Optimality, Christopher A. Cathcart

Graduate Theses and Dissertations

Scaling relations in tributary network geomorphology are well understood with respect to optimality. However, the scaling relations between structure and dynamics in distributary network geomorphology are less well understood. This is primarily due to the fact that nourishment area boundaries are difficult to map compared to tributary network catchment area boundaries. Furthermore, most previous work has focused either on the distributary channel networks or the delta’s partitioning of discharge. Here we show that, on the Wax Lake Delta (WLD) in Louisiana, the asymmetry in nourishment areas and downstream nourishment boundary width (∏) at a channel bifurcation, acts as a control …


An Exploration Into The Controls And Extent Of Capillary Rise In Fine-Grained Sand, Neal S. Turluck Aug 2019

An Exploration Into The Controls And Extent Of Capillary Rise In Fine-Grained Sand, Neal S. Turluck

Masters Theses

Capillary rise in fine-grained sands is especially important due to the wide distribution of fine-grained sediment throughout the unconsolidated sedimentary layers blanketing the earth. The height to which water rises above the water table in porous media is known as the capillary fringe. Tension pulling on the water molecules from the solid surfaces of pores will cause water to rise in the unconsolidated fine-grained sands until the water reaches equilibrium with the downward force of gravity.

Researching the controls behind capillary rise and being able to predict the extent to which water will rise in fine-grained sand helped provide insight …


Historical Floodplain Sedimentation Rates Using Mining Contaminant Profiles, Cesium-137, And Sediment Source Indicators Along The Lower Big River, Jefferson County, Missouri, Miranda M. Jordan Aug 2019

Historical Floodplain Sedimentation Rates Using Mining Contaminant Profiles, Cesium-137, And Sediment Source Indicators Along The Lower Big River, Jefferson County, Missouri, Miranda M. Jordan

Graduate Theses/Dissertations

Floodplain sedimentology and geochemistry can indicate the age of sediment layers to evaluate the history of human-caused sedimentation in a watershed. While the Ozark Highlands of Missouri has had a long history of settlement and land disturbance beginning in the early 1800s, there are few studies that have investigated the effects of these anthropogenic activities on river form and legacy sedimentation. The goal of this study is to characterize the sediment properties and geochemical trends in post-settlement floodplain deposits along lower Big River in Jefferson County, Missouri. This study evaluated trends of sediment properties at 3 cm intervals in a …


Assessing Bioavailability, Metal Fractionation, Magnetic Susceptibility, And Organic Matter Interactivity In Mine-Waste Contaminated Sediments In Turkey Creek, Joplin, Missouri, Zachary Joseph Collette Aug 2019

Assessing Bioavailability, Metal Fractionation, Magnetic Susceptibility, And Organic Matter Interactivity In Mine-Waste Contaminated Sediments In Turkey Creek, Joplin, Missouri, Zachary Joseph Collette

Graduate Theses/Dissertations

Joplin, Missouri, part of the Tri-State Mining District (TSMD), has a long history of mining that resulted in mine waste piles proximal to the mines throughout the area. A local lead smelter also resulted in smelter fallout in Joplin. Mine waste pile runoff and local smelter fallout resulted in contamination of sediments, soils, and waterways. In the 1990s, remediation of residential soils and play areas began after blood lead levels in children were much higher than the national average. Soon afterwards, the chat piles were removed and used for beneficial reuse purposes. In May of 2011, an EF5 tornado devastated …


Geomorphic And Land Use Controls On Headwater Channel Morphology In Mark Twain National Forest, Grace F. Roman Aug 2019

Geomorphic And Land Use Controls On Headwater Channel Morphology In Mark Twain National Forest, Grace F. Roman

Graduate Theses/Dissertations

Prescribed burning has been used over the past two decades to manage forests and restore shortleaf pine-oak woodlands in Mark Twain National Forest (MTNF). While soil studies have been completed, no assessments of burning practices on small drainage channel systems have yet been done. Headwater streams may account for more than two-thirds of total stream length and are important to the maintenance of hydrologic connectivity in watersheds. This study’s focus is on understanding the relationship between frequency of forest burning and channel morphology (size, shape, and substrate) of headwater streams (km2). A combination of field measurements, geo-processing methods, …


Geologic Mapping And Geochronology Of The Heavens Gate 7.5-Minute Quadrangle: How Long Does It Take To Accrete An Island Arc To A Continent?, Samuel Gordon Deyoung Aug 2019

Geologic Mapping And Geochronology Of The Heavens Gate 7.5-Minute Quadrangle: How Long Does It Take To Accrete An Island Arc To A Continent?, Samuel Gordon Deyoung

Graduate Theses/Dissertations

The Blue Mountain province of western Idaho and eastern Oregon is composed of a mélange of geologic terranes that represent Permian and Triassic island arcs that collided with North America in the Mesozoic, resulting in westward growth of the continent. Separating these accreted rocks from North America are the mid- crustal metamorphic rocks of the Salmon River suture zone. Containing units and features associated with the accreted island arc terranes and suture zone is the Heavens Gate 7.5-minute quadrangle, located in Idaho county, Idaho. Within the quadrangle the Salmon River suture zone is divided into structural blocks by a series …


Stream Channel Morphology And Riparian Forest Response To A 500-Year Flood In The Missouri Ozarks, Joshua William Hess Aug 2019

Stream Channel Morphology And Riparian Forest Response To A 500-Year Flood In The Missouri Ozarks, Joshua William Hess

Graduate Theses/Dissertations

Climate change has increased the frequency of large floods in rivers draining the Ozark Highlands resulting in higher rates of channel sedimentation, bank erosion, and damage to infrastructure. This study assesses the effects of a large flood (>500-year RI) during April-May 2017 on riparian forests along six tributary streams in the North Fork of the White River watershed, Missouri. High-resolution (<8 >cm) Unmanned Aerial Vehicle (UAV) imagery collected after the flood was used to identify riparian forest flood damage. Measurements of riparian forest flood damage calculated from the UAV imagery were verified through field surveys of damaged riparian trees. …


Consecutive Extreme Flooding And Heat Wave In Japan: Are They Becoming A Norm?, Shih-Yu Simon Wang, Hyungjun Kim, Dim Coumou, Jin-Ho Yoon, Lin Zhao, Robert R. Gillies Jul 2019

Consecutive Extreme Flooding And Heat Wave In Japan: Are They Becoming A Norm?, Shih-Yu Simon Wang, Hyungjun Kim, Dim Coumou, Jin-Ho Yoon, Lin Zhao, Robert R. Gillies

Plants, Soils, and Climate Faculty Publications

In July 2018, Japan experienced two contrasting, yet consecutive, extreme events: a devastating flood in early July followed by unprecedented heat waves a week later. Death tolls from these two extreme events combined exceeded 300, accompanying tremendous economic losses (BBC: July 24, 2018; AP: July 30, 2018). Meteorological analysis on these 2018 events quickly emerged (JMA-TCC, 2018; Kotsuki et al., 2019; Tsuguti et al., 2019), highlighting several compound factors: a strengthened subtropical anticyclone, a deepened synoptic trough, and Typhoon Prapiroon that collectively enhanced the Baiu rainband (the Japanese summer monsoon), fostering heavy precipitation. The comprehensive study of these events, conducted …


Lidar-Based Sinkhole Detection And Mapping In Knox County, Tennessee, J Clint Shannon, David Moore, Yingkui Li, Cathy Olsen Jul 2019

Lidar-Based Sinkhole Detection And Mapping In Knox County, Tennessee, J Clint Shannon, David Moore, Yingkui Li, Cathy Olsen

Pursuit - The Journal of Undergraduate Research at The University of Tennessee

Sinkholes are one of the major causes of damage to roads, buildings, and other infrastructure throughout the US. Sinkholes near or on roads are especially costly and occasionally deadly. Knox County and much of East Tennessee are located within karst areas (comprised of porous and soluble limestone and dolomite), deeming it at risk for sinkholes. Currently, Knox County uses contour maps to manually identify sinkholes. Supported by a geographic information system (GIS), we developed a streamlined model to identify the locations and extents of potential sinkholes using 1.3-ft resolution LiDAR (Light Detection and Ranging) data and applied it to the …


Eutherian Biogeography During The Puercan North American Land Mammal Age (Paleocene, Earliest Danian): Problems And Potential Solutions, Jason Sterling Silviria Jul 2019

Eutherian Biogeography During The Puercan North American Land Mammal Age (Paleocene, Earliest Danian): Problems And Potential Solutions, Jason Sterling Silviria

Earth and Planetary Sciences ETDs

The Puercan North American Land Mammal Age (NALMA) is the earliest major North American terrestrial biochron of the Cenozoic era, spanning roughly the first one million years of the Paleogene period (Paleocene epoch, Danian stage; ~66.04-65.12 Ma). It is typified by the explosive ecomorphological diversification of the mammalian clade Eutheria (particularly our subclade, Placentalia), following the annihilation of non-avian dinosaurs and “archaic” mammal groups during the Cretaceous/Paleogene (K-Pg) mass extinction event. The spatiotemporal mode and tempo of Puercan eutherian diversification has long been the subject of debate, with disagreements over biogeographic zonation. The traditional model – based largely on well-sampled, …


Changes In Mammalian Abundance Through The Eocene–Oligocene Climate Transition In The White River Group Of Nebraska, Usa, Robert Gillham Jul 2019

Changes In Mammalian Abundance Through The Eocene–Oligocene Climate Transition In The White River Group Of Nebraska, Usa, Robert Gillham

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Marine records show major cooling during the Eocene-Oligocene Climate Transition (EOCT). Most proxy studies in the White River Group suggest drying across the EOCT, and some suggest cooling. The lower resolution continental record has hindered a direct correlation of the marine climate record to Nebraska. I explore various correlation schemes and what they imply for faunal changes. This study compiles and analyzes data from 4,875 specimens in the University of Nebraska State Museum (UNSM) collection to test the hypothesis that climate change across the Eocene-Oligocene (E-O) boundary caused significant abundance changes in mammals. A series of binning schemes was created. …


Single Crystal Elasticity Of Hydrous Fe-Bearing Wadsleyite At High-Pressure Condition, Zhiyuan Ren Jul 2019

Single Crystal Elasticity Of Hydrous Fe-Bearing Wadsleyite At High-Pressure Condition, Zhiyuan Ren

Earth and Planetary Sciences ETDs

The 410-discontinuity separating the uppermost mantle from the transition zone is commonly believed to be caused by the olivine-wadsleyite transformation. However, the velocity change at the 410-discontinuity predicted by the standard pyrolitic model is not completely consistent with the seismic observations, leading to questions about the accuracy of the seismic models, or uncertainties of the mineral physics predictions. More regional seismic observations suggest that the depth, sharpness, and velocity jumps at the 410-discontinuity are different at different places, caused by thermal and/or compositional heterogeneities in the upper mantle. To explain the inconsistencies between the mineral physics and seismic models and …


Evaluating Sources Of Hydrochemical Variability And Mixing In The Upper Gila River, New Mexico, Pavel Vakhlamov Jul 2019

Evaluating Sources Of Hydrochemical Variability And Mixing In The Upper Gila River, New Mexico, Pavel Vakhlamov

Earth and Planetary Sciences ETDs

This study of the upper reaches of the Gila River basin in southwestern New Mexico reveals both spatial and seasonal patterns in physical and hydrochemical parameters. Monsoonal precipitation, temporal variability in water chemistry of streams in the upper Gila watershed is significantly impacted by surface runoff due to variability in landscape cover features, as well as surface area of the catchment. However, during base flow regimes spring inputs are the dominant drivers of solute concentrations and chemical variability.

Geothermal sources play a major role in salinization of the southwestern stream systems. Prolonged water/rock interaction combined with high temperature, pressure result …


An Early Modern Human Outside Africa, Eric Delson Jul 2019

An Early Modern Human Outside Africa, Eric Delson

Publications and Research

Analysis of two fossils from a Greek cave has shed light on early hominins in Eurasia. One fossil is the earliest known specimen of Homo sapiens found outside Africa; the other is a Neanderthal who lived 40,000 years later.


The Deepmip Contribution To Pmip4: Methodologies For Selection, Compilation And Analysis Of Latest Paleocene And Early Eocene Climate Proxy Data, Incorporating Version 0.1 Of The Deepmip Database, Christopher J. Hollis, Tom Dunkley Jones, Eleni Anagnostou, Peter K. Bijl, Margot J. Cramwinckel, Ying Cui, Gerald R. Dickens, Kirsty M. Edgar, Yvette Eley, David Evans, Gavin L. Foster, Joost Frieling, Gordon N. Inglis, Elizabeth M. Kennedy, Reinhard Kozdon, Vittoria Lauretano, Caroline H. Lear, Kate Littler, Lucas Lourens, A. Nele Meckler, B. David A. Naafs, Heiko Pälike, Richard D. Pancost, Paul N. Pearson, Ursula Röhl, Dana L. Royer, Ulrich Salzmann, Brian A. Schubert, Hannu Seebeck, Appy Sluijs, Robert P. Speijer, Peter Stassen Jul 2019

The Deepmip Contribution To Pmip4: Methodologies For Selection, Compilation And Analysis Of Latest Paleocene And Early Eocene Climate Proxy Data, Incorporating Version 0.1 Of The Deepmip Database, Christopher J. Hollis, Tom Dunkley Jones, Eleni Anagnostou, Peter K. Bijl, Margot J. Cramwinckel, Ying Cui, Gerald R. Dickens, Kirsty M. Edgar, Yvette Eley, David Evans, Gavin L. Foster, Joost Frieling, Gordon N. Inglis, Elizabeth M. Kennedy, Reinhard Kozdon, Vittoria Lauretano, Caroline H. Lear, Kate Littler, Lucas Lourens, A. Nele Meckler, B. David A. Naafs, Heiko Pälike, Richard D. Pancost, Paul N. Pearson, Ursula Röhl, Dana L. Royer, Ulrich Salzmann, Brian A. Schubert, Hannu Seebeck, Appy Sluijs, Robert P. Speijer, Peter Stassen

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The early Eocene (56 to 48 million years ago) is inferred to have been the most recent time that Earth's atmospheric CO2 concentrations exceeded 1000 ppm. Global mean temperatures were also substantially warmer than those of the present day. As such, the study of early Eocene climate provides insight into how a super-warm Earth system behaves and offers an opportunity to evaluate climate models under conditions of high greenhouse gas forcing. The Deep Time Model Intercomparison Project (DeepMIP) is a systematic model-model and model-data intercomparison of three early Paleogene time slices: latest Paleocene, Paleocene-Eocene thermal maximum (PETM) and early Eocene …


Management Regime And Habitat Response Influence Abundance Of Regal Fritillary (Speyeria Idalia) In Tallgrass Prairie, K. Mccullough, G. Albanese, D.A. Haukos, A.M. Ricketts, S. Stratton Jul 2019

Management Regime And Habitat Response Influence Abundance Of Regal Fritillary (Speyeria Idalia) In Tallgrass Prairie, K. Mccullough, G. Albanese, D.A. Haukos, A.M. Ricketts, S. Stratton

United States Geological Survey: Staff Publications

The >2,570,000-ha Flint Hills ecoregion of Kansas, USA, harbors the largest remaining contiguous tract of tallgrass prairie in North America, a unique system, as the remainder of North America’s tallgrass prairie has succumbed to development and conversion. Consequently, the loss and degradation of tallgrass prairie has reduced populations of many North American prairie-obligate species including the regal fritillary (Speyeria idalia) butterfly. Population abundance and occupied range of regal fritillary have declined >99%, restricting many populations to isolated, remnant patches of tallgrass prairie. Such extensive decline has resulted in consideration of the regal fritillary for protection under the Endangered Species Act. …


Perchlorate Behavior In The Context Of Black Carbon And Metal Cogeneration Following Fireworks Emission At Oak Lake, Lincoln, Nebraska, Usa, Manish Kumar, Daniel D. Snow, Yusong Li, Patrick Shea Jul 2019

Perchlorate Behavior In The Context Of Black Carbon And Metal Cogeneration Following Fireworks Emission At Oak Lake, Lincoln, Nebraska, Usa, Manish Kumar, Daniel D. Snow, Yusong Li, Patrick Shea

Nebraska Water Center: Faculty Publications

The imprints of fireworks displays on the adjacent water body were investigated from the perspective of cogeneration of black carbon, metals and perchlorate (ClO4–). In particular, the mixing and dissipation of ClO4– were studied at Oak Lake, Lincoln, Nebraska, following fireworks displays in 2015 and 2016. Following the display, ClO4– concentration in the water increased up to 4.3 μg/L and 4.0 μg/L in 2015 and 2016, respectively. A first-order model generally provided a good fit to the measured perchlorate concentrations from which the rate of dissipation was estimated as 0.07 d–1 in …


Fault Slip And Exhumation History Of The Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations To Wedge Propagation, Hinterland Uplift, And Foreland Basin Sedimentation, W. A. Yonkee, Bryan Eleogram, Michael L. Wells, Daniel F. Stockli, Shari Kelley, D. E. Barber Jul 2019

Fault Slip And Exhumation History Of The Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations To Wedge Propagation, Hinterland Uplift, And Foreland Basin Sedimentation, W. A. Yonkee, Bryan Eleogram, Michael L. Wells, Daniel F. Stockli, Shari Kelley, D. E. Barber

Geoscience Faculty Research

Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was …


Agriculture, Ecosystems & Environment, William A. Arigiroff, Donald R. Zak, Rima A. Upchurch, Sydney O. Salley, A. Stuart Grandy Jul 2019

Agriculture, Ecosystems & Environment, William A. Arigiroff, Donald R. Zak, Rima A. Upchurch, Sydney O. Salley, A. Stuart Grandy

Faculty Publications

Fine root litter is a primary source of soil organic matter (SOM), which is a globally important pool of C that is responsive to climate change. We previously established that ~20 years of experimental nitrogen (N) deposition has slowed fine root decay and increased the storage of soil carbon (C; +18%) across a widespread northern hardwood forest ecosystem. However, the microbial mechanisms that have directly slowed fine root decay are unknown. Here, we show that experimental N deposition has decreased the relative abundance of Agaricales fungi (−31%) and increased that of partially ligninolytic Actinobacteria (+24%) on decaying fine roots. Moreover, …


Co2-Enhanced Gas Recovery In Shale: Lessons Learned In The Devonian Ohio Shale Of Eastern Kentucky, Brandon C. Nuttall Jul 2019

Co2-Enhanced Gas Recovery In Shale: Lessons Learned In The Devonian Ohio Shale Of Eastern Kentucky, Brandon C. Nuttall

Report of Investigations--KGS

The Kentucky Geological Survey tested CO2-enhanced gas recovery in the Devonian shale in Johnson County, in response to a directive from the Kentucky General Assembly in 2007; the study site included a fracture-stimulated shale-gas well. To supplement a standard suite of open-hole logs acquired when the well was drilled, a well-logging program was designed to identify open perforations, construct a flow profile, and acquire pre-injection baseline data to characterize the Devonian Ohio Shale for a pressure falloff test. Tubing and packer were installed, with gel and brine filling the annulus between the tubing and packer to block flow-through …


Carbon And Nitrogen Stable Isotopes In Organic Matter From Lake Chalco, Mexico: A Record Of Quaternary Hydrology And Climate Change, Kristin Slezak Pearthree Jul 2019

Carbon And Nitrogen Stable Isotopes In Organic Matter From Lake Chalco, Mexico: A Record Of Quaternary Hydrology And Climate Change, Kristin Slezak Pearthree

Earth and Planetary Sciences ETDs

Sediment cores from Lake Chalco, central Mexico, were analyzed to reconstruct paleoclimate in the neotropics. This study employs total organic carbon, organic carbon-organic nitrogen ratios, carbon and nitrogen stable isotope ratios of organic matter (OM), and lithology to reconstruct changes in lake level and productivity. During Marine Isotope Stage 3 (~42-29 ka) bulk OM d13C and d15N results suggest the lake experienced strong evaporation and high pH due to warm temperatures and moderate precipitation. Large amounts of terrestrial C3 plant matter were deposited during the Last Glacial Maximum (~22-19 ka), suggesting a swampy environment resulting from …


Constraining The Oxygen Values Of The Late Cretaceous Western Interior Seaway Using Marine Bivalves, Camille H. Dwyer Jul 2019

Constraining The Oxygen Values Of The Late Cretaceous Western Interior Seaway Using Marine Bivalves, Camille H. Dwyer

Earth and Planetary Sciences ETDs

The Western Interior Seaway (WIS) remains an oceanographic enigma, including its circulation, similarity to the open ocean, and the fidelity of geochemical proxies to reconstruct paleoenvironments. Across the late Campanian and early Maastrichtian I test whether: 1) the WIS had unique δ18OVPDB compared to other marine settings, 2) increasing oceanographic restriction changed the stable isotope composition, and 3) biases, e.g., taxonomy or diagenesis, influenced stable isotope compositions. Results indicate distinct δ18OVPDB in the WIS compared to other marine settings. δ18OVPDB values were stable through time, suggesting insignificant oceanographic restriction and a …


Architecture And Evolution Of The Peace Vallis Distributive Fluvial System, Gale Crater, Mars, Zachary E. Gallegos Jul 2019

Architecture And Evolution Of The Peace Vallis Distributive Fluvial System, Gale Crater, Mars, Zachary E. Gallegos

Earth and Planetary Sciences ETDs

The Peace Vallis alluvial fan, located within Gale crater on the planet Mars, is a distributive fluvial system indicating a wet climate in Mars’ past. The Mars Science Laboratory rover instrument ChemCam, with the high-resolution Remote Micro-imager, was utilized to remotely explore the Peace Vallis alluvial fan and surrounding areas area. The Peace Vallis imaging campaigns 1 and 2, led by Dr. Horton Newsom and Zachary Gallegos respectively, acquired 20 distinct rover observations with a total of 243 individual images to investigate the fan. Using visual interpretation of the images and GIS techniques, this study interprets the processes and products …


Natural Salinization Of The Jemez River, New Mexico: An Insight From Trace Element Geochemistry, Jon K. Golla Jul 2019

Natural Salinization Of The Jemez River, New Mexico: An Insight From Trace Element Geochemistry, Jon K. Golla

Earth and Planetary Sciences ETDs

The Jemez River, a tributary of the Rio Grande in north-central New Mexico, receives thermal water input from the geofluids of the Valles Caldera, an active, high-temperature, liquid-dominated geothermal system. We focus on a ∼50-km portion of the northern Jemez River. This research extends previous decadal work (Crossey et al., in prep., 2013) on major chemistry in the river by characterizing the response of 16 trace elements to geochemical contributions from geothermal waters (McCauley, Spence, Soda Dam, and Jemez Springs springs and San Ysidro mineral waters), an area with copious hydrothermal degassing (Hummingbird), and two major tributaries (Rio San Antonio …


Thermotectonic History Of The Kluane Ranges And Evolution Of The Eastern Denali Fault Zone In Southwestern Yukon, Canada, Robert G. Mcdermott, Alexis K. Ault, Jonathan Saul Caine, Stuart N. Thomson Jul 2019

Thermotectonic History Of The Kluane Ranges And Evolution Of The Eastern Denali Fault Zone In Southwestern Yukon, Canada, Robert G. Mcdermott, Alexis K. Ault, Jonathan Saul Caine, Stuart N. Thomson

Geosciences Faculty Publications

Exhumation and landscape evolution along strike‐slip fault systems reflect tectonic processes that accommodate and partition deformation in orogenic settings. We present 17 new apatite (U‐Th)/He (He), zircon He, apatite fission‐track (FT), and zircon FT dates from the eastern Denali fault zone (EDFZ) that bounds the Kluane Ranges in Yukon, Canada. The dates elucidate patterns of deformation along the EDFZ. Mean apatite He, apatite FT, zircon He, and zircon FT sample dates range within ~26–4, ~110–12, ~94–28, and ~137–83 Ma, respectively. A new zircon U‐Pb date of 113.9 ± 1.7 Ma (2σ) complements existing geochronology and aids in interpretation …


An Estimation Of Lower Tropospheric Mixing Derived From Inverse Modeling Of Boundary Layer Water Vapor Isotopologues On Graciosa Island, Azores, Jacquelyn M. Delp Jul 2019

An Estimation Of Lower Tropospheric Mixing Derived From Inverse Modeling Of Boundary Layer Water Vapor Isotopologues On Graciosa Island, Azores, Jacquelyn M. Delp

Earth and Planetary Sciences ETDs

Recent studies have shown water vapor isotopologues to be sensitive tracers of mixing processes that govern low-cloud feedback in climate models. In this study, we develop an inverse model (MBL Mix inverse model) that uses one year of isotope and humidity observations from Graciosa Island, Azores to estimate mixing for four seasons. We show the dry end-member of the model, the lower free troposphere (LFT), can be represented using Rayleigh fractionation. Isotope observations from Graciosa Island are compared to other field locations to discuss controls on isotopic variability other than mixing. Output from the MBL Mix inverse model shows the …


Drought Analyses Of The Horn´E PoˇZitavie Region (Slovakia) In The Period 1966–2013, Jaroslav Vido, Paulina Nalevankova, Jan Valach, Zbysek Sustek, Tsegaye Tadesse Jul 2019

Drought Analyses Of The Horn´E PoˇZitavie Region (Slovakia) In The Period 1966–2013, Jaroslav Vido, Paulina Nalevankova, Jan Valach, Zbysek Sustek, Tsegaye Tadesse

National Drought Mitigation Center: Faculty Publications

+is study focuses on the characterization of historical drought occurrences in the Horn´e Poˇzitavie region of Slovakia over the period 1966–2013 using Standardized Precipitation-Evapotranspiration Index (SPEI). Trend analyses were evaluated by the Mann–Kendall (MK) test as well as cumulative sum of rank difference (CRD) test. +e results showed that drought occurs in the region regularly (recurrent climate feature), while the trend analysis indicated the trend toward more arid climatic conditions. However, CRD trend analyses showed that the subtrend changed direction toward less drier conditions in the late 1980s and early 1990s. Analyses of SPEI trends in individual months showed a …


Identifying Characteristics Of Actionable Science For Drought Planning And Adaptation, Adam Wilke, Amanda Cravens Jul 2019

Identifying Characteristics Of Actionable Science For Drought Planning And Adaptation, Adam Wilke, Amanda Cravens

United States Geological Survey: Publications

Changing climate conditions can make water management planning and drought preparedness decisions more complicated than ever before. Federal and State natural resource managers can no longer rely solely on historical trends as a baseline and thus are in need of science that is relevant to their specific needs to inform important planning decisions. Questions remain, however, regarding the most effective and efficient methods for extending scientific knowledge and products into management and decision-making. This project analyzed two unique cases of water management to better understand how science can be translated into resource management actions and decision-making, focusing particularly on how …


Evaluating Future Reservoir Storage In The Rio Grande Using Normalized Climate Projections And A Water Balance Model, Nolan T. Townsend Jul 2019

Evaluating Future Reservoir Storage In The Rio Grande Using Normalized Climate Projections And A Water Balance Model, Nolan T. Townsend

Earth and Planetary Sciences ETDs

We develop and implement new tools for assessing the future of surface water supplies in downstream reaches of the Rio Grande, for which Elephant Butte Reservoir is the major storage reservoir. First, a normalization procedure is developed to adjust natural Rio Grande streamflows simulated by dynamical models in downstream reaches. The normalization accounts for upstream anthropogenic impairments to flow that are not considered in the model, thereby yielding downstream flows closer to observed values and more appropriate for use in assessments of future flows in downstream reaches. The normalization is applied to assess the potential effects of climate change on …