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2017

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Articles 31 - 60 of 120

Full-Text Articles in Soil Science

Laboratory Resistivity Measurements For Soil Characterization, Behdad Mofarraj Kouchaki Aug 2017

Laboratory Resistivity Measurements For Soil Characterization, Behdad Mofarraj Kouchaki

Graduate Theses and Dissertations

Field based electrical resistivity measurements, such as electrical resistivity tomography (ERT) and capacitively coupled resistivity (CCR), are geophysical methods that offer a non-destructive and rapid means to collect continuous data. As such, ERT and CCR are becoming increasingly popular tools for geotechnical engineers; however, it is challenging to derive geotechnical information such as soil type, density, and water content from the data. A laboratory geophysical investigation was carried out to gain a better understanding of the parameters that affect the electrical resistivity of soils and devise a relationship between resistivity and soil type or classification. In this study, a soil …


Sedimentary Characteristics And Nutrient Sequestration Of Embanked Floodplains Along The Lower Mississippi River, Mississippi And Louisiana, R M Malitha Rathnayake Aug 2017

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 …


Geology And Paleontology Along Part Of The Niobrara River In Northern Nebraska, Robert Matthew Joeckel, S. T. Tucker, Leslie M. Howard Aug 2017

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.


Soil Ecosystem Service Tradeoffs And Social–Ecological Resilience In The North Central Great Plains, Hannah E. Birge Aug 2017

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 …


Characterization Of The Relationships Between Soybean Yield, Trifoliolate Leaf Chloride Concentration, And Cultivar Chloride Inclusion/Exclusion Rating, Dillon Cox Aug 2017

Characterization Of The Relationships Between Soybean Yield, Trifoliolate Leaf Chloride Concentration, And Cultivar Chloride Inclusion/Exclusion Rating, Dillon Cox

Graduate Theses and Dissertations

Chloride toxicity is recognized as yield limiting problem in soybean [Glycine max (L.) Merr.] production. Limited information is available to accurately diagnose and manage Cl toxicity. The only recommendation for Cl toxicity management is to plant an excluder cultivar, however the cultivar Cl sensitivity rating system (excluder, includer, and mixed) does not appear to capture the variability in cultivar Cl tolerance. The objectives of this research were to i) develop critical tissue-Cl concentrations in which yield loss occurs for excluder and includer cultivars and ii) investigate the variability in cultivar Cl ratings. A study was conducted across five site-years using …


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 Jul 2017

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 …


Assessing Coastal Plain Risk Indices For Subsurface Phosphorus Loss, Amy L. Shober, Anthony R. Buda, Kathryn C. Turner, Nicole M. Fiorellino, A. Scott Andres, Joshua M. Mcgrath, J. Thomas Sims Jul 2017

Assessing Coastal Plain Risk Indices For Subsurface Phosphorus Loss, Amy L. Shober, Anthony R. Buda, Kathryn C. Turner, Nicole M. Fiorellino, A. Scott Andres, Joshua M. Mcgrath, J. Thomas Sims

Plant and Soil Sciences Faculty Publications

Phosphorus (P) Index evaluations are critical to advancing nutrient management planning in the United States. However, most assessments until now have focused on the risks of P losses in surface runoff. In artificially drained agroecosystems of the Atlantic Coastal Plain, subsurface flow is the predominant mode of P transport, but its representation in most P Indices is often inadequate. We explored methods to evaluate the subsurface P risk routines of five P Indices from Delaware, Maryland (two), Virginia, and North Carolina using available water quality and soils datasets. Relationships between subsurface P risk scores and published dissolved P loads in …


The Application Of Aem To Mapping The Aquifer And Groundwater Characteristics Of The La Grange Groundwater Area, Wa, David Annetts, Tim Munday, Richard J. George Dr, Nicholas J. Wright, Gregory Paul Raper, Kevin Cahill Jul 2017

The Application Of Aem To Mapping The Aquifer And Groundwater Characteristics Of The La Grange Groundwater Area, Wa, David Annetts, Tim Munday, Richard J. George Dr, Nicholas J. Wright, Gregory Paul Raper, Kevin Cahill

Natural resources commissioned reports

This report describes the interpretation of a large airborne electromagnetic data survey that was designed to aid characterisation of groundwater systems in the La Grange groundwater allocation area which lies south of Broome, Western Australia. Characterisation of these systems is critical to developing policy around water use in the region, especially for the development of agriculture. This report is the second of two reports and it is designed to refine surfaces which are used as inputs to groundwater models. The volume defined by these surfaces viz. the seawater intrusion in the west, the top of the Jarlemai siltstone and the …


An Overview Of Secondary Aquifers In Nebraska, Dana Divine, Steven S. Sibray Jul 2017

An Overview Of Secondary Aquifers In Nebraska, Dana Divine, Steven S. Sibray

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Conservation Farming And Changing Climate: More Beneficial Than Conventional Methods For Degraded Ugandan Soils, Drake N. Mubiru, Jalia Namakula, James Lwasa, Godfrey A. Otim, Joselyn Kashagama, Milly Nakafeero, William Nanyeenya, Mark S. Coyne Jun 2017

Conservation Farming And Changing Climate: More Beneficial Than Conventional Methods For Degraded Ugandan Soils, Drake N. Mubiru, Jalia Namakula, James Lwasa, Godfrey A. Otim, Joselyn Kashagama, Milly Nakafeero, William Nanyeenya, Mark S. Coyne

Plant and Soil Sciences Faculty Publications

The extent of land affected by degradation in Uganda ranges from 20% in relatively flat and vegetation-covered areas to 90% in the eastern and southwestern highlands. Land degradation has adversely affected smallholder agro-ecosystems including direct damage and loss of critical ecosystem services such as agricultural land/soil and biodiversity. This study evaluated the extent of bare grounds in Nakasongola, one of the districts in the Cattle Corridor of Uganda and the yield responses of maize (Zea mays) and common bean (Phaseolus vulgaris L.) to different tillage methods in the district. Bare ground was determined by a supervised multi-band …


Seedling Tolerance To Cotyledon Removal Varies With Seed Size: A Case Of Five Legume Species, Xiao Wen Hu, Rui Zhang, Yan Pei Wu, Carol C. Baskin Jun 2017

Seedling Tolerance To Cotyledon Removal Varies With Seed Size: A Case Of Five Legume Species, Xiao Wen Hu, Rui Zhang, Yan Pei Wu, Carol C. Baskin

Biology Faculty Publications

It is generally accepted that seedlings from large seeds are more tolerant to defoliation than those from small seeds due to the additional metabolic reserves present in the large seeds. However, information on the effects of amount of seed reserves (cotyledon removal) from seedlings resulting from large vs. small seeds on seedling growth and long-term survival in the field is limited. Five legume species with different sizes of seeds were sown in the field and none, one, or both cotyledons removed 7 days after seedling emergence. Seedling biomass, relative growth rate (RGR) and survival were determined at different time. Cotyledon …


Divergence In Life History Traits Between Two Populations Of A Seed-Dimorphic Halophyte In Response To Soil Salinity, Fan Yang, Jerry M. Baskin, Carol C. Baskin, Xuejun Yang, Dechang Cao, Zhenying Huang Jun 2017

Divergence In Life History Traits Between Two Populations Of A Seed-Dimorphic Halophyte In Response To Soil Salinity, Fan Yang, Jerry M. Baskin, Carol C. Baskin, Xuejun Yang, Dechang Cao, Zhenying Huang

Biology Faculty Publications

Production of heteromorphic seeds is common in halophytes growing in arid environments with strong spatial and temporal heterogeneity. However, evidence for geographic variation (reflecting local adaptation) is almost nonexistent. Our primary aims were to compare the life history traits of two desert populations of this halophytic summer annual Suaeda corniculata subsp. mongolica and to investigate the phenotypic response of its plant and heteromorphic seeds to different levels of salt stress. Dimorphic seeds (F1) of the halophyte S. corniculata collected from two distant populations (F0) that differ in soil salinity were grown in a common environment under …


Interpretive Geologic Cross Sections Across Lower Platte North Natural Resources District, Nebraska (Ccs-20), Dana Divine Jun 2017

Interpretive Geologic Cross Sections Across Lower Platte North Natural Resources District, Nebraska (Ccs-20), Dana Divine

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Noncanonical Alternative Polyadenylation Contributes To Gene Regulation In Response To Hypoxia, Laura De Lorenzo, Reed Sorenson, Julia Bailey-Serres, Arthur G. Hunt Jun 2017

Noncanonical Alternative Polyadenylation Contributes To Gene Regulation In Response To Hypoxia, Laura De Lorenzo, Reed Sorenson, Julia Bailey-Serres, Arthur G. Hunt

Plant and Soil Sciences Faculty Publications

Stresses from various environmental challenges continually confront plants, and their responses are important for growth and survival. One molecular response to such challenges involves the alternative polyadenylation of mRNA. In plants, it is unclear how stress affects the production and fate of alternative mRNA isoforms. Using a genome-scale approach, we show that in Arabidopsis thaliana, hypoxia leads to increases in the number of mRNA isoforms with polyadenylated 3′ ends that map to 5′-untranslated regions (UTRs), introns, and protein-coding regions. RNAs with 3′ ends within protein-coding regions and introns were less stable than mRNAs that end at 3′-UTR poly(A) sites. …


Global Land Carbon Sink Response To Temperature And Precipitation Varies With Enso Phase, Yuanyuan Fang, Anna M. Michalak, Christopher R. Schwalm, Deborah N. Huntzinger, Joseph A. Berry, Philippe Ciais, Shilong Piao, Benjamin Poulter, Joshua B. Fisher, Robert B. Cook, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul Jain, Huimin Lei, Chaoqun Lu, Jiafu Mao, Nicholas C. Parazoo, Shushi Peng, Daniel M. Ricciuto, Xiaoying Shi, Bo Tao, Hanqin Tian, Weile Wang, Yaxing Wei, Jia Yang Jun 2017

Global Land Carbon Sink Response To Temperature And Precipitation Varies With Enso Phase, Yuanyuan Fang, Anna M. Michalak, Christopher R. Schwalm, Deborah N. Huntzinger, Joseph A. Berry, Philippe Ciais, Shilong Piao, Benjamin Poulter, Joshua B. Fisher, Robert B. Cook, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul Jain, Huimin Lei, Chaoqun Lu, Jiafu Mao, Nicholas C. Parazoo, Shushi Peng, Daniel M. Ricciuto, Xiaoying Shi, Bo Tao, Hanqin Tian, Weile Wang, Yaxing Wei, Jia Yang

Plant and Soil Sciences Faculty Publications

Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. Here, we show that the dominant driver varies with ENSO phase. Whereas tropical temperature explains sink dynamics following El Niño conditions (r TG,P = 0.59, p …


Nutrient Addition Shifts Plant Community Composition Towards Earlier Flowering Species In Some Prairie Ecoregions In The U.S. Central Plains, Lori Biederman, Brent Mortensen, Philip Fay, Nicole Hagenah, Johannes Knops, Kimberly La Pierre, Ramesh Laungani, Eric Lind, Rebecca L. Mcculley, Sally Power, Eric Seabloom, Pedro Tognetti May 2017

Nutrient Addition Shifts Plant Community Composition Towards Earlier Flowering Species In Some Prairie Ecoregions In The U.S. Central Plains, Lori Biederman, Brent Mortensen, Philip Fay, Nicole Hagenah, Johannes Knops, Kimberly La Pierre, Ramesh Laungani, Eric Lind, Rebecca L. Mcculley, Sally Power, Eric Seabloom, Pedro Tognetti

Plant and Soil Sciences Faculty Publications

The distribution of flowering across the growing season is governed by each species’ evolutionary history and climatic variability. However, global change factors, such as eutrophication and invasion, can alter plant community composition and thus change the distribution of flowering across the growing season. We examined three ecoregions (tall-, mixed, and short-grass prairie) across the U.S. Central Plains to determine how nutrient (nitrogen (N), phosphorus, and potassium (+micronutrient)) addition alters the temporal patterns of plant flowering traits. We calculated total community flowering potential (FP) by distributing peak-season plant cover values across the growing season, allocating each species’ cover to only those …


Use Of Annual Phosphorus Loss Estimator (Aple) Model To Evaluate A Phosphorus Index, Nicole M. Fiorellino, Joshua M. Mcgrath, Peter A. Vadas, Carl H. Bolster, Frank J. Coale May 2017

Use Of Annual Phosphorus Loss Estimator (Aple) Model To Evaluate A Phosphorus Index, Nicole M. Fiorellino, Joshua M. Mcgrath, Peter A. Vadas, Carl H. Bolster, Frank J. Coale

Plant and Soil Sciences Faculty Publications

The Phosphorus (P) Index was developed to provide a relative ranking of agricultural fields according to their potential for P loss to surface water. Recent efforts have focused on updating and evaluating P Indices against measured or modeled P loss data to ensure agreement in magnitude and direction. Following a recently published method, we modified the Maryland P Site Index (MD-PSI) from a multiplicative to a component index structure and evaluated the MD-PSI outputs against P loss data estimated by the Annual P Loss Estimator (APLE) model, a validated, field-scale, annual P loss model. We created a theoretical dataset of …


Validating A Universal Model Of Particle Transport Lengths With Laboratory Measurements Of Suspended Grain Motions, Robert C. Mahon, Brandon Mcelroy, Suleyman Naqshband May 2017

Validating A Universal Model Of Particle Transport Lengths With Laboratory Measurements Of Suspended Grain Motions, Robert C. Mahon, Brandon Mcelroy, Suleyman Naqshband

Earth and Environmental Sciences Faculty Publications

t The mechanics of sediment transport are of fundamental importance for fluvio-deltaic morphodynamics. The present study focuses on quantifying particle motions and trajectories across a wide range of flow conditions. In particular, a continuous model is presented that predicts particle travel distances for saltation and suspension based on Rouse number and relative grain roughness. By utilizing a series of eight video cameras in a plexiglass flume direct measurements of the distributions of particle travel distances (excursion lengths) were obtained. To this end, experiments were carried out in dark under black lights with fluorescent painted plastic and quartz sand particles. For …


Soil Science Lesson Plan For The Cal Poly Learn By Doing Lab, Kelsey Ormonde May 2017

Soil Science Lesson Plan For The Cal Poly Learn By Doing Lab, Kelsey Ormonde

Natural Resources Management and Environmental Sciences

To increase interest in soil science and other related sciences, educational materials need to be tailored to appeal to younger students. The purpose of this project was to create a soil science lesson plan that could be utilized by the Cal Poly Learn By Doing Lab. Information from several articles, textbooks, lesson plans, and websites was reviewed to create a soil science lesson plan for students in 5-8th grade. The lesson plan focused on the three sub-disciplines of soil science; physical, chemical, and biological. Activities were created to correspond to the three sub-disciplines. Alternate activities were created to allow …


Development Of A Multiband Remote Sensing System For Determination Of Unsaturated Soil Properties, Cyrus D. Garner May 2017

Development Of A Multiband Remote Sensing System For Determination Of Unsaturated Soil Properties, Cyrus D. Garner

Graduate Theses and Dissertations

A multiband system including active microwave sensing and visible-near infrared reflectance spectroscopy was developed to measure unsaturated soil properties in both field and laboratory environments. Remote measurements of soil volumetric water content (θv), soil water matric potential (ψ), and soil index properties (liquid limit [LL], plastic limit [PL], and clay fraction [CF]) were conducted. Field-based measurement of θv was conducted using a ground-based radar system and field measurements within 10 percentage points of measurements acquired with traditional sampling techniques were obtained. Laboratory-based, visible and near infrared spectroscopy was found to be capable of obtaining empirical, soil specific regression functions (partial …


Influence Of Prescribed Burning On Upland Soil Properties In Mark Twain National Forest, Southeast Missouri Ozarks, Megan Lynn Hente May 2017

Influence Of Prescribed Burning On Upland Soil Properties In Mark Twain National Forest, Southeast Missouri Ozarks, Megan Lynn Hente

Graduate Theses/Dissertations

In the Mark Twain National forest there is a collaborative effort to restore parts of the forest to its original shortleaf pine-oak woodland areas by using a combination of silviculture and prescribed fire. The purpose of this project is to assess the effects of prescribed burning on upland forest and soil physical properties that influence erosion processes across a gradient of burned sites of different ages and unburned sites. A combination of geospatial, field, laboratory, statistical (one-way ANOVA) and modeling (USLE) methods were used to assess the effects of prescribed burns on forest and soil characteristics in Big Barren Creek …


Sclerocactus Wetlandicus: Habitat Characterization, Seed Germination And Mycorrhizal Analysis, Kourtney T. Harding May 2017

Sclerocactus Wetlandicus: Habitat Characterization, Seed Germination And Mycorrhizal Analysis, Kourtney T. Harding

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Uinta Basin hookless cactus (Sclerocactus wetlandicus) is a threatened species native to Eastern Utah. The cactus is found in a landscape highly disturbed by non-renewable energy production. To understand the environmental conditions that support natural growth of this cactus, we asked what types of plants were present in the same areas as the cactus, and if the types of plants were different in environments that were disturbed. From our assessment, we determined that the types of plants present in disturbed areas were drastically different from those present in undisturbed locations. Areas previously used for energy production are …


Effect Of Foliage And Root Carbon Quantity, Quality, And Fluxes On Soil Organic Carbon Stabilization In Montane Aspen And Conifer Stands In Utah, Antra Boča May 2017

Effect Of Foliage And Root Carbon Quantity, Quality, And Fluxes On Soil Organic Carbon Stabilization In Montane Aspen And Conifer Stands In Utah, Antra Boča

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Soil organic carbon (SOC) positively affects many soil properties (e.g., fertility and water holding capacity), and the amount of carbon (C) in soil exceeds the amount in the atmosphere by about three times. Forest soils store as much C as is found in trees. Tree species differ in their effect on SOC pools. Quaking aspen forests in the Western US often store more stable SOC in the mineral soil than nearby conifers. During the last decades a decline in aspen cover, often followed by conifer encroachment, has been documented. A shift from aspen to conifer overstories may negatively affect the …


Draft Nuclear Genome Sequence Of The Liquid Hydrocarbon–Accumulating Green Microalga Botryococcus Braunii Race B (Showa), Daniel R. Browne, Jerry Jenkins, Jeremy Schmutz, Shengqiang Shu, Kerrie Barry, Jane Grimwood, Jennifer Chiniquy, Aditi Sharma, Thomas Daniel Niehaus, Taylor L. Weiss, Andrew T. Koppisch, David T. Fox, Suraj Dhungana, Shigeru Okada, Joe Chappell, Timothy P. Devarenne Apr 2017

Draft Nuclear Genome Sequence Of The Liquid Hydrocarbon–Accumulating Green Microalga Botryococcus Braunii Race B (Showa), Daniel R. Browne, Jerry Jenkins, Jeremy Schmutz, Shengqiang Shu, Kerrie Barry, Jane Grimwood, Jennifer Chiniquy, Aditi Sharma, Thomas Daniel Niehaus, Taylor L. Weiss, Andrew T. Koppisch, David T. Fox, Suraj Dhungana, Shigeru Okada, Joe Chappell, Timothy P. Devarenne

Plant and Soil Sciences Faculty Publications

Botryococcus braunii has long been known as a prodigious producer of liquid hydrocarbon oils that can be converted into combustion engine fuels. This draft genome for the B race of B. braunii will allow researchers to unravel important hydrocarbon biosynthetic pathways and identify possible regulatory networks controlling this unusual metabolism.


Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali Apr 2017

Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali

Chemistry Faculty Publications

How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence …


Accelerated Increase In The Arctic Tropospheric Warming Events Surpassing Stratospheric Warming Events During Winter, Shih-Yu (Simon) Wang, Yen-Heng Lin, Ming-Ying Lee, Jin-Ho Yoon, Jonathan D.D. Meyer, Philip J. Rasch Apr 2017

Accelerated Increase In The Arctic Tropospheric Warming Events Surpassing Stratospheric Warming Events During Winter, Shih-Yu (Simon) Wang, Yen-Heng Lin, Ming-Ying Lee, Jin-Ho Yoon, Jonathan D.D. Meyer, Philip J. Rasch

Plants, Soils, and Climate Faculty Publications

In January 2016, a robust reversal of the Arctic Oscillation (AO) took place associated with a rapid tropospheric warming in the Arctic region; this was followed by the occurrence of a classic sudden stratospheric warming in March-April. The succession of these two distinct Arctic warming events provides a stimulating opportunity to examine their characteristics in terms of similarities and differences. Historical cases of these two types of Arctic warming were identified and validated based upon tropical linkages with the Madden-Julian Oscillation and El Niño as well as those documented in previous studies. Our results indicate a recent and accelerated increase …


Evaluating The Impacts Of Grassland Conversions To Experimental Forest On Groundwater Recharge In The Nebraska Sand Hills, Zablon A. Adane Apr 2017

Evaluating The Impacts Of Grassland Conversions To Experimental Forest On Groundwater Recharge In The Nebraska Sand Hills, Zablon A. Adane

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

The Nebraska Sand Hills grasslands provide the greatest groundwater recharge rates in the High Plains Aquifer. However, the grasslands and their ecological services have become vulnerable to land use change and degradation. This study used a series of field data to investigate the effects of grassland conversions to forest on recharge rates in a century-old experimental forest in the Sand Hills. The results show that the impact of grassland conversion on recharge was dependent on the species and plantation density. Estimated recharge rates beneath the dense plantations represent reductions of 86–94% relative to the native grassland. Results of 1H …


Alicyclic And Aromatic Carboxylic Acids In Soil Organic Matter: An Investigation Of Potential Origin And Association With Plutonium Using Advanced Analytical Techniques, Nicole Didonato Apr 2017

Alicyclic And Aromatic Carboxylic Acids In Soil Organic Matter: An Investigation Of Potential Origin And Association With Plutonium Using Advanced Analytical Techniques, Nicole Didonato

Chemistry & Biochemistry Theses & Dissertations

Carboxylic acids are a defining component of soil organic matter, responsible for many of the physical and chemical properties, including metal-organic matter interactions, which govern its role as an important constituent of soils. However, there is a shortage of detailed molecular level information regarding orientation and structural arrangement of carboxylic acids within soil organic matter. This dissertation utilizes electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) as well as solid-state and multi-dimensional nuclear magnetic resonance (NMR) to investigate the molecular formula composition within several organic matter sources and the primary structures that feature carboxylic acids. Soil organic matter …


Modeling The Movement Of Septic Water Chloride Through A Soil Profile, Shawkat Kochary, Tom Byl, Bahzad Noori Mar 2017

Modeling The Movement Of Septic Water Chloride Through A Soil Profile, Shawkat Kochary, Tom Byl, Bahzad Noori

Civil and Architectural Engineering Faculty Research

The purpose of this study was to investigate the movement of chloride through a vadose zone located under failed and non-regulated septic tanks of Duhok city, Kurdistan of Iraq, potentially contaminating its groundwater. A physical vadose model (PVM) of a vertical flow direction was built in the laboratory to represent the city soil profile. The size of the PVM was 210 × 122 × 9.7 cm (height, width, and depth). Preliminary soil tests were conducted to better represent the lithology of study area. The PVM was then packed with regional silt clay soil, after modifying its texture, using an innovative …


Responses Of Terrestrial Ecosystem Phosphorus Cycling To Nitrogen Addition: A Meta-Analysis, Qi Deng, Dafeng Hui, Samuel Dennis, Chandra Reddy Mar 2017

Responses Of Terrestrial Ecosystem Phosphorus Cycling To Nitrogen Addition: A Meta-Analysis, Qi Deng, Dafeng Hui, Samuel Dennis, Chandra Reddy

Agricultural and Environmental Sciences Faculty Research

Aim

Anthropogenic additions of nitrogen (N) are expected to drive terrestrial ecosystems toward greater phosphorus (P) limitation. However, a comprehensive understanding of how an ecosystem's P cycle responds to external N inputs remains elusive, making model predictions of the anthropogenic P limitation and its impacts largely uncertain.

Location

Global.

Time period

1986-2015.

Major taxa studied

Terrestrial ecosystems.

Methods

We conducted a meta-analysis including 288 independent study sites from 192 articles to evaluate global patterns and controls of 10 variables associated with ecosystem P cycling under N addition.

Results

Overall, N addition increased biomass in plants (+34%) and litter (+15%) as …