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Articles 12661 - 12690 of 17799
Full-Text Articles in Entire DC Network
Investigating Core Shale Depositional Environments Of Late Pennsylvanian Cyclothems Utilizing Geochemical Proxies To Test The Superestuarine Model, Bryce A. Mathis
Investigating Core Shale Depositional Environments Of Late Pennsylvanian Cyclothems Utilizing Geochemical Proxies To Test The Superestuarine Model, Bryce A. Mathis
LSU Master's Theses
The Late Paleozoic Midcontinent Sea (LPMS) inundated vast areas of the North American interior during glacio-eustatic transgressions, depositing widespread black shales facies within the core shale intervals of major cyclothems. These black shale deposits are unique because no modern analogs can adequately explain the depositional environments and model for organic matter preservation across such vast ancient epicontinental settings. One possible explanation is that a superestuarine circulation system developed across the LPMS during humid interglacial phases, which promoted strong water column stratification and benthic anoxia.
The goal of this research was to test the validity of the superestuarine estuarine model and …
Biofuels From Crop Residue: Soil Organic Carbon And Climate Impacts In The Us And India, Adam Liska
Biofuels From Crop Residue: Soil Organic Carbon And Climate Impacts In The Us And India, Adam Liska
Adam Liska Papers
The transformation of crop residue to soil organic carbon and CO2 is a conserved process that occurs globally. Due to the mathematics of carbon intensity calculations found in government regulations, the amount of CO2 emitted from crop residue per unit of energy in biofuel is largely independent of the amount of residue removed and the location of its removal, as shown by results from the US and India.
Soil organic carbon (SOC) levels are at equilibria determined by carbon inputs from plant material (+Ic) and loss from oxidation to CO2
Are the US results relevant …
Variability In Methane Emissions From West Siberia's Shallow Boreal Lakes On A Regional Scale And Its Environmental Controls, Aleksandr F. Sabrekov, Benjamin R.K. Runkle, Mikhail V. Glagolev, Irina E. Terentieva, Victor M. Stephanenko, Oleg R. Kotsyurbenko, Shamil S. Maksyutov, Oleg S. Pokrovsky
Variability In Methane Emissions From West Siberia's Shallow Boreal Lakes On A Regional Scale And Its Environmental Controls, Aleksandr F. Sabrekov, Benjamin R.K. Runkle, Mikhail V. Glagolev, Irina E. Terentieva, Victor M. Stephanenko, Oleg R. Kotsyurbenko, Shamil S. Maksyutov, Oleg S. Pokrovsky
Biological and Agricultural Engineering Faculty Publications and Presentations
Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July–August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m−2 h−1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m−2 h−1 for southern taiga lakes, respectively. …
Respons Tanaman Kedelai (Glycine Max) Varietas Wilis Akibat Pemberian Berbagai Dosis Pupuk N, P, K, Dan Pupuk Guano Pada Tanah Inceptisol Jatinangor, Agus Wahyudin, Fiky Yulianto Wicaksono, Aep Wawan Irwan, Ruminta, Rizka Fitriani
Respons Tanaman Kedelai (Glycine Max) Varietas Wilis Akibat Pemberian Berbagai Dosis Pupuk N, P, K, Dan Pupuk Guano Pada Tanah Inceptisol Jatinangor, Agus Wahyudin, Fiky Yulianto Wicaksono, Aep Wawan Irwan, Ruminta, Rizka Fitriani
Jurnal Kultivasi
Penelitian ini bertujuan untuk melihat apakah pemberian Pupuk Organik Padat Guano dapat memberikan hasil yang sama dengan pemberian Pupuk N,P,K. Percobaan dilakukan di Rumah Kaca Fakultas Pertanian Universitas Padjadjaran, Jatinangor dengan ketinggian 754m dpl dan menggunakan tanah inceptisol dengan pH 6,18.Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok, terdiri dari 8 perlakuan kombinasi dosis pupuk, yang terdiri dari 100% N,P,K, 100% Pupuk Guano, 75% N,P,K + 100% Pupuk Guano, 50% N,P,K + 100% Pupuk Guano, 75% N,P,K + 75% Pupuk Guano, 50% N,P,K + 75% Pupuk Guano, 75% N,P,K + 50% Pupuk Guano serta 50% N,P,K + 50% Pupuk Guano. …
Respons Pertumbuhan Dan Hasil Benih Kentang G0 Di Dataran Medium Terhadap Waktu Dan Cara Aplikasi Paklobutrazol, Nuzula Suci Azima, Anne Nuraini, Sumadi, Jajang Sauman Hamdani
Respons Pertumbuhan Dan Hasil Benih Kentang G0 Di Dataran Medium Terhadap Waktu Dan Cara Aplikasi Paklobutrazol, Nuzula Suci Azima, Anne Nuraini, Sumadi, Jajang Sauman Hamdani
Jurnal Kultivasi
Aplikasi paklobutrazol pada penanaman kentang di dataran medium dapat mengurangi sintesis giberelin yang menyebabkan penurunan hasil kentang. Efektifitas paklobutrazol tidak hanya dipengaruhi oleh konsentrasi, tetapi juga waktu dan cara aplikasinya. Tujuan penelitian ini adalah untuk memperoleh waktu dan cara aplikasi paklobutrazol yang memberikan pengaruh paling baik dalam meningkatkan hasil benih kentang G0 di dataran medium. Rancangan penelitian menggunakan Rancangan Acak Kelompok (RAK) Faktorial dengan 3 ulangan. Perlakuannya terdiri dari waktu aplikasi paklobutrazol yaitu 28, 35 dan 42 HST (Hari Setelah Tanam) dan cara aplikasi paklobutrazol yaitu disemprot ke daun, disiram ke media tanam dan kombinasi antara penyemprotan ke daun dan …
Reducing Equifinality Using Isotopes In A Process-Based Stream Nitrogen Model Highlights The Flux Of Algal Nitrogen From Agricultural Streams, William I. Ford, James F. Fox, Erik Pollock
Reducing Equifinality Using Isotopes In A Process-Based Stream Nitrogen Model Highlights The Flux Of Algal Nitrogen From Agricultural Streams, William I. Ford, James F. Fox, Erik Pollock
Biosystems and Agricultural Engineering Faculty Publications
The fate of bioavailable nitrogen species transported through agricultural landscapes remains highly uncertain given complexities of measuring fluxes impacting the fluvial N cycle. We present and test a new numerical model named Technology for Removable Annual Nitrogen in Streams For Ecosystem Restoration (TRANSFER), which aims to reduce model uncertainty due to erroneous parameterization, i.e., equifinality, in stream nitrogen cycle assessment and quantify the significance of transient and permanent removal pathways. TRANSFER couples nitrogen elemental and stable isotope mass‐balance equations with existing hydrologic, hydraulic, sediment transport, algal biomass, and sediment organic …
A Machine Learning Approach To Estimation Of Downward Solar Radiation From Satellite-Derived Data Products: An Application Over A Semi-Arid Ecosystem In The U.S., Qingtao Zhou, Alejandro Flores, Nancy F. Glenn, Reggie Walters, Bangshuai Han
A Machine Learning Approach To Estimation Of Downward Solar Radiation From Satellite-Derived Data Products: An Application Over A Semi-Arid Ecosystem In The U.S., Qingtao Zhou, Alejandro Flores, Nancy F. Glenn, Reggie Walters, Bangshuai Han
Geosciences Faculty Publications and Presentations
Shortwave solar radiation is an important component of the surface energy balance and provides the principal source of energy for terrestrial ecosystems. This paper presents a machine learning approach in the form of a random forest (RF) model for estimating daily downward solar radiation flux at the land surface over complex terrain using MODIS (MODerate Resolution Imaging Spectroradiometer) remote sensing data. The model-building technique makes use of a unique network of 16 solar flux measurements in the semi-arid Reynolds Creek Experimental Watershed and Critical Zone Observatory, in southwest Idaho, USA. Based on a composite RF model built on daily observations …
Cytonuclear Discordance In The Florida Everglades Invasive Burmese Python (Python Bivittatus) Population Reveals Possible Hybridization With The Indian Python (P. Molurus), Margaret E. Hunter, Nathan A. Johnson, Brian J. Smith, Michelle C. Davis, John S.S. Butterfield, Ray W. Snow, Kristen M. Hart
Cytonuclear Discordance In The Florida Everglades Invasive Burmese Python (Python Bivittatus) Population Reveals Possible Hybridization With The Indian Python (P. Molurus), Margaret E. Hunter, Nathan A. Johnson, Brian J. Smith, Michelle C. Davis, John S.S. Butterfield, Ray W. Snow, Kristen M. Hart
United States Geological Survey: Staff Publications
The invasive Burmese python (Python bivittatus) has been reproducing in the Florida Everglades since the 1980s. These giant constrictor snakes have caused a precipitous decline in small mammal populations in southern Florida following escapes or releases from the commercial pet trade. To better understand the invasion pathway and genetic composition of the population, two mitochondrial (mtDNA) loci across 1,398 base pairs were sequenced on 426 snakes and 22 microsatellites were assessed on 389 snakes. Concatenated mtDNA sequences produced six haplotypes with an average nucleotide and haplotype diversity of π = 0.002 and h = 0.097, respectively. Samples collected …
On The Pursuit Of Relevance In Standards-Based Curriculum Development: The Ccny Approach, Angelo Lampousis
On The Pursuit Of Relevance In Standards-Based Curriculum Development: The Ccny Approach, Angelo Lampousis
Publications and Research
The Society for Standards Professionals (SES) has a significant history of documenting the use of standards in research and academia. For instance, during the 62nd Annual SES Conference in 2013 in Savannah, Georgia, the author participated in such a session highlighting examples of relationships between academic institutions, government, and standards developing organizations. In this article, we attempt to capture the current advances made from similar relationships specific to our home institution, the City College of New York (CCNY) of the City University of New York (CUNY.) These advances have become possible through a grant issued under the Standards Services Curricula …
Magnesium Isotope Investigation Of Stromatolitic Knobs In Storr’S Lake, San Salvador, Bahamas: Implications For Organomineralization And Laminae Formation, Zijian Li
Earth & Environmental Sciences Theses - Archive
Storr’s Lake, a hypersaline lake located on San Salvador Island, Bahamas, contains modern, fine-grained stromatolites. This study focused on two morphological types of stromatolitic mounds in Storr’s Lake (pinnacle mound and plateau-mushroom) and systematically investigated their mineralogy, elemental abundance, carbon, oxygen and magnesium (Mg) isotopic signature to gain insights into the organomineralization process and laminae formation of stromatolites. In addition, the hydrochemistry of Storr’s Lake was characterized by in situ measurement of water parameters, elemental analysis, and Mg isotope investigation. Cations and anions analysis indicates the lake is spatially homogenous and shows little seasonal variation. Mg isotope analysis of the …
Dental Microwear Textures Of Paranthropus Robustus From Kromdraai, Drimolen, And An Enlarged Sample From Swartkrans: Ecological And Intraspecific Variation, Alexandria Sachiko Peterson
Dental Microwear Textures Of Paranthropus Robustus From Kromdraai, Drimolen, And An Enlarged Sample From Swartkrans: Ecological And Intraspecific Variation, Alexandria Sachiko Peterson
Graduate Theses and Dissertations
The original microwear texture baseline for South African hominins was done by Scott et al. (2005) and concluded that Paranthropus robustus exhibited higher complexity values (Asfc) that are seen in occasional hard object feeders. Australopithecus africanus has higher anisotropy values (epLsar) consistent with consuming tough objects. This study expands upon this baseline by increasing the sample size from n = 9 for P. robustus and n = 10 for Au. africanus to n = 66 and n = 44, respectively. Additionally, this study incorporates multiple different sites and deposits. The P. robustus sample includes Drimolen, Kromdraai, and an expanded sample …
Geology And Paleontology Along Part Of The Niobrara River In Northern Nebraska, Robert Matthew Joeckel, S. T. Tucker, Leslie M. Howard
Geology And Paleontology Along Part Of The Niobrara River In Northern Nebraska, Robert Matthew Joeckel, S. T. Tucker, Leslie M. Howard
Conservation and Survey Division: Faculty and Staff Publications
No abstract provided.
Using Stable Isotope Geochemistry To Determine Changing Paleohydrology And Diagenetic Alteration In The Late Cretaceous Kaiparowits Formation, Ut Usa, Daigo Yamamura
Graduate Theses and Dissertations
The Western Interior Basin of the North America preserves one of the best sedimentary and paleontological records of the Cretaceous in the world. The Upper Cretaceous Kaiparowits Formation is a rapidly deposited fluvial sequence and preserves one of the most complete terrestrial fossil record of the North America. Such a unique deposit provides an opportunity to investigate the interaction between the physical environment and ecology. In an effort to decipher such interaction, stable isotope composition of cements in sedimentary rocks, concretions and vertebrate fossils were analyzed.
Despite the difference in facies and sedimentary architecture, the isotope composition does not change …
Understanding Cigarette Butt Littering Behavior On Public Beaches: A Case Study Of Jekyll Island, Georgia, Maranda R. Miller
Understanding Cigarette Butt Littering Behavior On Public Beaches: A Case Study Of Jekyll Island, Georgia, Maranda R. Miller
School of Natural Resources: Dissertations, Theses, and Student Research
The world’s natural environment is degrading, and human behavior is a leading cause. Therefore, in order to address environmental problems it is important to understand the factors driving environmentally degrading behaviors and subsequently design behavioral interventions to alter undesirable behaviors.
One environmental issue of particular concern is toxins leeching from trash. Specifically, cigarette butts are of concern due to their prevalence in the environment. Cigarette butt discarding behavior is affected by personal attributes, but data regarding which personal attributes and how these affect discarding behavior is lacking. This thesis seeks to understand cigarette butt disposal on public beaches by exploring …
Soil Ecosystem Service Tradeoffs And Social–Ecological Resilience In The North Central Great Plains, Hannah E. Birge
Soil Ecosystem Service Tradeoffs And Social–Ecological Resilience In The North Central Great Plains, Hannah E. Birge
School of Natural Resources: Dissertations, Theses, and Student Research
Humans seek to improve their wellbeing by altering ecological processes to maximize the output of specific ecosystem services, which often leave the system vulnerable to unintended and undesirable side effects. Ecosystem services emerge from complex interactions among ecological structures and processes occurring at multiple scales. The degree to which an ecosystem maintains a predictable range of structures and processes in the face of disturbance can be described as its resilience. The 1930s Dust Bowl of the North American Great Plains is an example of a system reconfiguration and loss of resilience that was ultimately driven by human optimization for a …
Characterizing The Fate And Mobility Of Phosphorus In Utah Lake Sediments, Matthew Chambers Randall
Characterizing The Fate And Mobility Of Phosphorus In Utah Lake Sediments, Matthew Chambers Randall
Theses and Dissertations
An increasing number of lakes worldwide are impacted by eutrophication and harmful algal blooms due to nutrient inputs. Utah Lake is a unique eutrophic freshwater lake that is naturally shallow, turbid, and alkaline with high dissolved oxygen levels. Recently, the Utah Division of Water Quality has proposed a new limitation of phosphorus (P) loading to Utah Lake from wastewater treatment plants in an effort to mitigate eutrophication. However, reducing external P loads may not lead to immediate improvements in water quality due to the legacy pool of nutrients in lake sediments. The purpose of this study was to characterize the …
Development Of Lower Rio Grande River Water Quality Transportation Numerical Model For Bi-National River Management, Jose O. Gonzalez
Development Of Lower Rio Grande River Water Quality Transportation Numerical Model For Bi-National River Management, Jose O. Gonzalez
Theses and Dissertations
Traditionally, water quality modelling has focused on modelling individual water bodies. However, water quality management problems must be analyzed at the larger scale to include influences from various water bodies that are interconnected. This paper provides a study on the hydrologic and quality transportation calculation by developing a hydrodynamic (unsteady state) channel routing model using a water-balanced approach. A one dimension Lagrangian river model was developed and applied to the 210 plus miles for the lower Rio Grande River Basin from the Falcon Dam to the head water of Brownsville that pours onto the Gulf of Mexico. This model can …
Groundwater Flow Tracing In Carter Saltpeter Cave And Toll Branch, Carter County, Tn, Aaron G. Doyka
Groundwater Flow Tracing In Carter Saltpeter Cave And Toll Branch, Carter County, Tn, Aaron G. Doyka
Electronic Theses and Dissertations
Groundwater tracing studies have shown a well-developed conduit system in the karst aquifer beneath the Buffalo Creek Watershed of Carter County, TN. Groundwater can quickly travel beneath topographic divides, transporting contaminants. Using GIS and field reconnaissance, two sites were selected for a two phase dye trace study. In May-June 2016 groundwater resurgences were located using activated carbon samplers, and in October-December 2016 flow velocities were measured using ISCO automatic water samplers. In study 1, a stream sinking in the back of Carter Saltpeter Cave was traced to its resurgence at Cave Springs Cave. In study 2, the dye mass centroid …
Sedimentary Characteristics And Nutrient Sequestration Of Embanked Floodplains Along The Lower Mississippi River, Mississippi And Louisiana, R M Malitha Rathnayake
Sedimentary Characteristics And Nutrient Sequestration Of Embanked Floodplains Along The Lower Mississippi River, Mississippi And Louisiana, R M Malitha Rathnayake
Master's Theses
The Mississippi River Basin is the largest river basin in North America and the third largest river basin in the world. Most of the corn, soybeans, wheat, cattle, and hogs harvested in the United States come from the Mississippi River Basin and about 58% of the entire drainage basin is croplands. Runoff from these lands carries sediments and nutrients, and the Mississippi River transports these downstream and ultimately deposits them in the Gulf of Mexico. The northern Gulf of Mexico is one of largest human-caused hypoxic zones in the world. Hypoxia is the phenomena where the dissolved oxygen level decreases …
The Significant Surface-Water Connectivity Of “Geographically Isolated Wetlands”, Aram J. K. Calhoun, David M. Mushet, Laurie C. Alexander, Edward S. Dekeyser, Laurie Fowler, Charles R. Lane, Megan W. Lang, Mark C. Rains, Stephen C. Richter, Susan C. Walls
The Significant Surface-Water Connectivity Of “Geographically Isolated Wetlands”, Aram J. K. Calhoun, David M. Mushet, Laurie C. Alexander, Edward S. Dekeyser, Laurie Fowler, Charles R. Lane, Megan W. Lang, Mark C. Rains, Stephen C. Richter, Susan C. Walls
School of Geosciences Faculty and Staff Publications
We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands based on the singular condition of being surrounded by uplands. The most recent research on wetlands considered to be “geographically isolated” shows the difficulties in grouping an ecological resource that does not reliably indicate lack of surface water connectivity in order to meet legal, regulatory, or scientific needs. Additionally, the practice of identifying “geographically isolated wetlands” based on distance from a stream can …
Vulnerability Assessment Of Groundwater To No3 Contamination Using Gis, Drastic Model And Geostatistical Analysis, Adela Beauty Adu Agyemang
Vulnerability Assessment Of Groundwater To No3 Contamination Using Gis, Drastic Model And Geostatistical Analysis, Adela Beauty Adu Agyemang
Electronic Theses and Dissertations
The study employed Geographical Information System (GIS) technology to investigate the vulnerability of groundwater to NO3 content in Buncombe County, North Carolina in two different approaches. In the first study, the spatial distribution of NO3 contamination was analyzed in a GIS environment using Kriging Interpolation. Cokriging interpolation was used to establish how NO3 relates to land cover types and depth to water table of wells in the county. The second study used DRASTIC model to assess the vulnerability of groundwater in Buncombe County to NO3 contamination. To get an accurate vulnerability index, the DRASTIC parameters were …
Quantifying Riverbed Sediment Using Recreational-Grade Side Scan Sonar, Daniel Hamill
Quantifying Riverbed Sediment Using Recreational-Grade Side Scan Sonar, Daniel Hamill
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The Colorado River in Glen, Marble, and Grand Canyons is subject to a complex regulatory framework, including the Colorado River Compact, the Endangered Species Act, and the Grand Canyon Protection Act of 1992. Physical, biological, and cultural resources are extensively monitored by the Glen Canyon Dam Adaptive Management Program (GCDAMP) to assess the effect of Glen Canyon Dam (GCD) operations on the downstream environment. The GCDAMP consists of a diverse group of stakeholders who identify priority resources and agree upon water releases at GCD. Large expenditures of money have been devoted to monitoring physical and biological resources in Grand Canyon. …
Impact Of Salinity Change On Water Quality Variables From The Sediment Of An Artificial Lake Under Anaerobic Conditions, Tae-Hoon Kim, James Jihoon Kang, Sang Hyun Kim, I-Song Choi, Kwang-Hyeon Chang, Jong Min Oh, Ki-Hyun Kim
Impact Of Salinity Change On Water Quality Variables From The Sediment Of An Artificial Lake Under Anaerobic Conditions, Tae-Hoon Kim, James Jihoon Kang, Sang Hyun Kim, I-Song Choi, Kwang-Hyeon Chang, Jong Min Oh, Ki-Hyun Kim
School of Earth, Environmental, & Marine Sciences Faculty Publications
Artificial reservoirs are created by dike construction in coastal areas to secure the agricultural water supply on the west coast of South Korea. These systems are found to retain brackish characteristics until total desalination is achieved. To evaluate the effects of salinity on the organic substances released from the sediment, a laboratory water-sediment column experiment was conducted to assess associated changes in water quality variables such as the sediment oxygen demand (SOD), chemical oxygen demand (COD), and concentrations of nitrogen (N) and phosphorus (P). Under high salinity conditions, the release of N from the sediment was promoted with the enhancement …
Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee
Geochemistry Of Volatiles Released By Incipient Continental Rifting And Subduction Processes, Hyunwoo Lee
Earth and Planetary Sciences ETDs
Volatiles (N2, CO2, and He) are released by volcanism and hydrothermal activity during continental rifting and subduction processes. Analyses of volatile components have been conducted to obtain gas contents (CO2, SO2, H2S, N2, Ar, He, and so on), stable isotope compositions (δ13C, δ15N, and so on), and noble gas isotopes (3He/4He, 40Ar/36Ar, and so on). This dissertation includes four chapters to report new nitrogen isotope fractionation factors of bubbling gases during gas-water transfer at various water temperatures (Chapter 1), first measurements of massive amounts of CO2 released by incipient continental rifting in the Magadi and Natron Basin, East African Rift …
Microfeatures Of Modern Sea-Ice-Rafted Sediment And Implications For Paleo-Sea-Ice Reconstructions, Kristen E. St. John, Sandra Passchier, Brooke Tantillo, Dennis Darby, Lance Kearns
Microfeatures Of Modern Sea-Ice-Rafted Sediment And Implications For Paleo-Sea-Ice Reconstructions, Kristen E. St. John, Sandra Passchier, Brooke Tantillo, Dennis Darby, Lance Kearns
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Distinguishing sea-ice-rafted debris (SIRD) from iceberg-rafted debris is crucial to an interpretation of ice-rafting history; however, there are few paleo-sea-ice proxies. This study characterizes quartz grain microfeatures of modern SIRD from the Arctic Ocean, and compares these results with microfeatures from representative glacial deposits to potentially differentiate SIRD from ice-rafted sediments which have been recently subjected to glacial processes. This allows us to evaluate the use of grain microfeatures as a paleo-sea-ice proxy. SIRD grains were largely subrounded, with medium relief, pervasive silica dissolution and a high abundance of breakage blocks and microlayering. The glacial grains were more angular, with …
Effects Of Climate Warming On Net Primary Productivity In China During 1961–2010, Fengxue Gu, Yuandong Zhang, Mei Huang, Bo Tao, Rui Guo, Changrong Yan
Effects Of Climate Warming On Net Primary Productivity In China During 1961–2010, Fengxue Gu, Yuandong Zhang, Mei Huang, Bo Tao, Rui Guo, Changrong Yan
Plant and Soil Sciences Faculty Publications
The response of ecosystems to different magnitudes of climate warming and corresponding precipitation changes during the last few decades may provide an important reference for predicting the magnitude and trajectory of net primary productivity (NPP) in the future. In this study, a process-based ecosystem model, Carbon Exchange between Vegetation, Soil and Atmosphere (CEVSA), was used to investigate the response of NPP to warming at both national and subregional scales during 1961–2010. The results suggest that a 1.3°C increase in temperature stimulated the positive changing trend in NPP at national scale during the past 50 years. Regardless of the magnitude of …
Trilobite Extinctions, Facies Changes And The Roece Carbon Isotope Excursion At The Cambrian Series 2–3 Boundary, Great Basin, Western Usa, Luke E. Faggetter, Paul B. Wignall, Sara B. Pruss, Robert J. Newton, Yadong Sun, Stephen F. Crowley
Trilobite Extinctions, Facies Changes And The Roece Carbon Isotope Excursion At The Cambrian Series 2–3 Boundary, Great Basin, Western Usa, Luke E. Faggetter, Paul B. Wignall, Sara B. Pruss, Robert J. Newton, Yadong Sun, Stephen F. Crowley
Geosciences: Faculty Publications
The mass extinction of the olenellid trilobites occurred around the Cambrian Series 2–Series 3 boundary. Like many other crises, it coincided with a negative carbon isotope excursion but the associated palaeoenvironmental changes remain unclear. To investigate the causal mechanism for this event, we report facies changes, pyrite framboid petrography and carbon isotope values from Cambrian Series 2–Series 3 (traditionally Early–Middle Cambrian) boundary strata of the Carrara Formation (Death Valley region, California) and Pioche Formation (Nevada). These data reveal regionally changing water depths from high-energy, nearshore facies (oolitic grainstone) to more offshore silty marl and finer-grained carbonate mudstone. In the Carrara …
Examining The Use Of Amazon’S Mechanical Turk For Edge Extraction Of The Occlusal Surface Of Fossilized Bovid Teeth, George K. Thiruvathukal, Gregory J. Matthews, Maxwell P. Luetkemeier, Juliet K. Brophy
Examining The Use Of Amazon’S Mechanical Turk For Edge Extraction Of The Occlusal Surface Of Fossilized Bovid Teeth, George K. Thiruvathukal, Gregory J. Matthews, Maxwell P. Luetkemeier, Juliet K. Brophy
Computer Science: Faculty Publications and Other Works
In order to reconstruct environments associated with Plio-Pleistocene hominins in southern Africa, researchers frequently rely upon the animals associated with the hominins, in particular, animals in the Family Bovidae. Bovids in southern Africa are typically identified by their teeth. However, identifying the taxon of a bovid tooth is challenging due to various biasing factors. Furthermore, inaccurate identification of fossil bovids can have significant consequences on the reconstructed paleoenvironment. Recent research on the classification of bovid fossil teeth has relied on using elliptical Fourier analysis to summarize the shape of the outline of the occlusal surface of the tooth and the …
High-Resolution Elevation Mapping Of The Mcmurdo Dry Valleys, Antarctica, And Surrounding Regions, Andrew G. Fountain, Juan C. Fernandez-Diaz, Maciej K. Obryk, Joseph Levy, Michael N. Gooseff, David J. Van Horn, Paul Morin, Ramesh Shrestha
High-Resolution Elevation Mapping Of The Mcmurdo Dry Valleys, Antarctica, And Surrounding Regions, Andrew G. Fountain, Juan C. Fernandez-Diaz, Maciej K. Obryk, Joseph Levy, Michael N. Gooseff, David J. Van Horn, Paul Morin, Ramesh Shrestha
Geology Faculty Publications and Presentations
We present detailed surface elevation measurements for the McMurdo Dry Valleys, Antarctica derived from aerial lidar surveys flown in the austral summer of 2014–2015 as part of an effort to understand geomorphic changes over the past decade. Lidar return density varied from 2 to > 10 returns m−2with an average of about 5 returns m−2. Vertical and horizontal accuracies are estimated to be 7 and 3 cm, respectively. In addition to our intended targets, other ad hoc regions were also surveyed including the Pegasus flight facility and two regions on Ross Island, McMurdo Station, Scott Base (and surroundings), and the coastal …
The Potential Effects Of Percolating Snowmelt On Palynological Records From Firn And Glacier Ice, Michael E. Ewin, Carl A. Reese, Matthew A. Nolan
The Potential Effects Of Percolating Snowmelt On Palynological Records From Firn And Glacier Ice, Michael E. Ewin, Carl A. Reese, Matthew A. Nolan
Faculty Publications
The effects of meltwater percolation on pollen in snow, firn and glacial ice are not fully understood and currently hamper the use of pollen in ice-core studies of paleoclimate. Several studies have suggested that, due to grain size, pollen is not mobilized by meltwater transport. However, these findings contradict many ice-core pollen studies that show pollen concentrations in snow and firn are much higher than concentrations found in the ice layers they eventually form. This study addresses one aspect of this question by investigating whether meltwater percolation can effectively transport pollen within a snowpack. We used nine Styrofoam coolers filled …