Digital Commons Network^™

Flux Of Particulate Elements In The North Atlantic Ocean Constrained By Multiple Radionuclides, Christopher T. Hayes, Erin E. Black, Robert F. Anderson, Mark Baskaran, Ken O. Buesseler, Matthew A. Charette, Hai Cheng, J. Kirk Cochran, R. Lawrence Edwards, Patrick Fitzgerald, Phoebe J. Lam, Yanbin Lu, Stephanie O. Morris, Daniel C. Ohnemus, Frank J. Pavia, Gillian Stewart, Yi Tang

Environmental Science and Geology Faculty Research Publications

Sinking particles strongly regulate the distribution of reactive chemical substances in the ocean, including particulate organic carbon and other elements (e.g., P, Cd, Mn, Cu, Co, Fe, Al, and 232Th). Yet, the sinking fluxes of trace elements have not been well described in the global ocean. The U.S. GEOTRACES campaign in the North Atlantic (GA03) offers the first data set in which the sinking flux of carbon and trace elements can be derived using four different radionuclide pairs (238U:234Th ;210Pb:210Po; 228Ra:228Th; and 234U:230Th) at stations co-located with sediment trap fluxes for comparison. Particulate organic carbon, particulate P, and particulate Cd …

Relating Cyanobacteria And Physicochemical Water-Quality Properties In Willow Creek Lake, Nebraska, 2012–14, David L. Rus, Brent M. Hall, Steven A. Thomas

United States Geological Survey: Water Reports and Publications

Document abstract

Cyanobacteria (also referred to as blue-green algae) are naturally present members of phytoplankton assemblages that may detract from beneficial uses of water because some strains produce cyanotoxins that pose health hazards to people and animals. Cyanobacteria populations observed in Willow Creek Lake during 2012 through 2014 were compared to external nutrient loading from the Willow Creek drainage basin and several other physicochemical properties within the lake, including internal nutrient loading. This report is part of a cooperative study between the United States Geological Survey, the Lower Elkhorn Natural Resources District, the Nebraska Department of Environmental Quality, the Nebraska …

A Time Series Of Water Column Distributions And Sinking Particle Flux Of Pseudo-Nitzschia And Domoic Acid In The Santa Barbara Basin, California, Blaire P. Umhau, Claudia R. Benitez-Nelson, Clarissa R. Anderson, Kelly Mccabe, Christopher Burrell

Faculty Publications

Water column bulk Pseudo-nitzschia abundance and the dissolved and particulate domoic acid (DA) concentrations were measured in the Santa Barbara Basin (SBB), California from 2009–2013 and compared to bulk Pseudo-nitzschia cell abundance and DA concentrations and fluxes in sediment traps moored at 147 m and 509 m. Pseudo-nitzschia abundance throughout the study period was spatially and temporally heterogeneous (L⁻¹ to 3.8 × 10⁶ cells L⁻¹, avg. 2 × 10⁵ ± 5 × 10⁵ cells L⁻¹) and did not correspond with upwelling conditions or the total DA (tDA) concentration, which was also spatially …

Proceedings Of The First Annual Symposium On The Wright State Woods, College Of Science And Mathematics, College Of Liberal Arts

1st Annual Wright State Woods Symposium

The proceeding of the Woods Symposium held at Wright State University and sponsored by the College of Science and Mathematics and the College of Liberal Arts.

Sedimentology And Stratigraphy Of Core Stl14: An Early Pleistocene-To-Present Paleoclimate Archive From Stoneman Lake, Arizona, Spencer Staley

Earth and Planetary Sciences ETDs

An 80 m lacustrine sediment core (STL14) from Stoneman Lake, Coconino County, Arizona, contains a sedimentary sequence of at least 1.5 million years, chronicling the complete history of basin infill and recording an extensive and high-resolution archive of climatic and hydrologic fluctuations. Lake levels in this small, internally-drained catchment are sensitive to changes in regional hydrologic balance. Consistent groundwater inflow, even during regionally dry episodes in the lake’s history, has prevented complete desiccation of the lake and sustained continuous lacustrine deposition except for one soil horizon. Multiproxy analysis of sedimentological indicators including lithofacies, color, wet bulk density, magnetic susceptibility, preliminary …

Water, Energy, And Carbon Footprints Of Bioethanol From The U.S. And Brazil, Mesfin Mekonnen, Thiago L. Romanelli, Chittaranjan Ray, Arjen Y. Hoekstra, Adam Liska, Christopher M. U. Neale

Adam Liska Papers

Driven by biofuel policies, which aim to reduce greenhouse gas (GHG) emissions and increase domestic energy supply, global production and consumption of bioethanol have doubled between 2007 and 2016, with rapid growth in corn-based bioethanol in the U.S. and sugar cane-based bioethanol in Brazil. Advances in crop yields, energy use efficiency in fertilizer production, biomass-to-ethanol conversion rates, and energy efficiency in ethanol production have improved the energy balance and GHG emission reduction potential of bioethanol. In the current study, the water, energy, and carbon footprints of bioethanol from corn in the U.S. and sugar cane in Brazil were assessed. The …

Optical Remote Sensing Of Oil Spills In The Gulf Of Mexico, Shaojie Sun

USF Tampa Graduate Theses and Dissertations

Assessment of oil spills in the ocean using passive remote sensing (i.e., reflected sun light) faces two challenges: detect oil presence/absence and quantify oil volume. While the optical properties of oil allow it to be differentiated from the surrounding marine environment, sun glint can facilitate oil presence/absence detection because the oil-water spatial contrast is enhanced due to wave dampening. However, sun glint also modulates the magnitude and shape of the spectral reflectance of surface oil. In addition to this difficulty, the most critical challenge is how to quantify oil volume (or thickness) through remote sensing. To date, such quantifications have …

Reduced Carbon Use Efficiency And Increased Microbial Turnover With Soil Warming, Jianwei Li, Gangsheng Wang, Melanie A. Mayes, Steven D. Allison, Serita D. Frey, Zheng Shi, Xiao-Ming Hu, Yiqi Luo, Jerry M. Melillo

Agricultural and Environmental Sciences Faculty Research

Global soil carbon (C) stocks are expected to decline with warming, and changes in microbial processes are key to this projection. However, warming responses of critical microbial parameters such as carbon use efficiency (CUE) and biomass turnover (rB) are not well understood. Here, we determine these parameters using a probabilistic inversion approach that integrates a microbial-enzyme model with 22 years of carbon cycling measurements at Harvard Forest. We find that increasing temperature reduces CUE but increases rB, and that two decades of soil warming increases the temperature sensitivities of CUE and rB. These temperature sensitivities, which are derived from decades-long …

Reduced Carbon Use Efficiency And Increased Microbial Turnover With Soil Warming, Jianwei Li, Gangsheng Wang, Melanie A. Mayes, Steven D. Allison, Serita D. Frey, Zheng Shi, Xiao-Ming Hu, Yiqi Luo, Jerry M. Melillo

Faculty Publications

Global soil carbon (C) stocks are expected to decline with warming, and changes in microbial processes are key to this projection. However, warming responses of critical microbial parameters such as carbon use efficiency (CUE) and biomass turnover (rB) are not well understood. Here, we determine these parameters using a probabilistic inversion approach that integrates a microbial-enzyme model with 22 years of carbon cycling measurements at Harvard Forest. We find that increasing temperature reduces CUE but increases rB, and that two decades of soil warming increases the temperature sensitivities of CUE and rB. These temperature sensitivities, which are derived from decades-long …

Modulation Of Auxin And Cytokinin Responses By Early Steps Of The Phenylpropanoid Pathway, Jasmina Kurepa, Timothy E. Shull, Sumudu S. Karunadasa, Jan A. Smalle

Plant and Soil Sciences Faculty Publications

Background: The phenylpropanoid pathway is responsible for the synthesis of numerous compounds important for plant growth and responses to the environment. In the first committed step of phenylpropanoid biosynthesis, the enzyme phenylalanine ammonia-lyase (PAL) deaminates L-phenylalanine into trans-cinnamic acid that is then converted into p-coumaric acid by cinnamate-4-hydroxylase (C4H). Recent studies showed that the Kelch repeat F-box (KFB) protein family of ubiquitin ligases control phenylpropanoid biosynthesis by promoting the proteolysis of PAL. However, this ubiquitin ligase family, alternatively named Kiss Me Deadly (KMD), was also implicated in cytokinin signaling as it was shown to promote the degradation of …

Spatial Variation In Throughfall, Soil, And Plant Water Isotopes In A Temperate Forest, Gregory R. Goldsmith, Scott T. Allen, Sabine Braun, Nadine Engbersen, Clara Romero González-Quijano, James W. Kirchner, Rolf T. W. Siegwolf

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Studies of stable isotopes of water in the environment have been fundamental to advancing our understanding of how water moves through the soil‐plant‐atmosphere continuum; however, much of this research focuses on how water isotopes vary in time, rather than in space. We examined the spatial variation in the δ¹⁸O and δ²H of throughfall and bulk soil water, as well as branch xylem and bulk leaf water of Picea abies (Norway Spruce) and Fagus sylvatica (Beech), in a 1 ha forest plot in the northern Alps of Switzerland. Means and ranges of water isotope ratios varied considerably …

Sediment Dynamics In The Bear River-Mud Lake-Bear Lake System, Patrick Belmont, Mitchell Donovan, Janice Brahney, Lindsay Capito, Zach Burgert

Watershed Sciences Faculty Publications

The overarching goal of this project was to compile and analyze a variety of existing datasets, and generate several new datasets, to advance our understanding of how the Bear River Mud Lake-Bear Lake system functions, how it has, or is expected to change, identify which components are degraded or vulnerable to degradation, and determine if/where critical data and/or knowledge gaps exist. We conducted a series of analyses to evaluate changes in hydrology and suspended sediment, collected sediment cores from nine locations in Mud Lake to evaluate how sedimentation rates, sediment sources and water quality have changed over time, and utilized …

Microbial Diversity In Urban Environments: Concern For Antibiotic Resistance, Ality Aghedo, Mangala Tawde, Nazrul I. Khandaker

Publications and Research

We are almost oblivious to the presence of microorganisms in our daily lives, but they exist and come into contact with us all the time. While some bacteria are harmless, and even beneficial, other bacteria can cause infections. A common treatment to bacterial infections is antibiotics and the success of an antibiotic depends on the resistance of the bacteria to the antibiotic. We conducted experiments to identify the types of bacteria that can be found on surfaces or within soil environments that come into contact with a vast number of people on a daily basis and how this can affect …

Recruiting And Retaining K9–16 Students Through Field- And Laboratory - Based Geoscience Experiences, Nazrul I. Khandaker, Stanley Schleifer, Arif M. Sikder, Krishna Mahabir, Ality Aghedo, Charren Cabaroy, Mildred M. Selby, Gugu Ginindza, Leonardo Sanchez

Publications and Research

Since 2004, we have been directly involved with the GSA to provide access and opportunities for K9-16 students, particularly those interested in the broader aspects of geoscience-related topics, to present their field-and- laboratory based research outcomes at professional conferences and to learn from each other. So far, well-over 400 students from the U. S. and abroad have taken advantage of this opportunity and participated our topical sessions. It is quite gratifying to report that many of these students, as a result of their attendance at the GSA conference, felt a continuing need for exposure to high-level professional venues with effective …

Measuring And Modeling Evolution Of Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Felix Jacob Zamora

Dissertations and Theses

Cryoconite holes are vertical columns of meltwater within the shallow subsurface of glaciers. In the McMurdo Dry Valleys (MDV) of Antarctica cryoconite holes are a source of meltwater and harbor microbial communities in an otherwise arid environment with low biologic activity. The holes form as sediments on the ice surface, which are darker than the surrounding ice, are preferentially heated by solar radiation. The warm sediments melt the underlying ice and migrate downwards. An ice lid forms, isolating them from the below-freezing atmosphere enabling them to remain thawed. In this study, field observations, laboratory experiments, and numerical modeling are used …

Examining Patterns In Nest Predation Using Artificial Nests, Victoria L. Simonsen

School of Natural Resources: Dissertations, Theses, and Student Research

The use of artificial nests to study the predation of avian nests has faced disregard by ecologists due to inconsistencies found between the survival rates of real and artificial nests across studies and reviews. The negative perception of artificial nests providing an inconsistent assessment of survival has thus fostered the perception that artificial nests are a secondary option to be used to overcome logistical hurdles associated with achieving sufficient sample sizes in systems where study species are rare or elusive, or as merely a preliminary method to study predation across gradients. We argue that the greatest mistake ecologists have made …

Groundwater Recharge Response To Reduced Irrigation Pumping In Western Nebraska, Justin Philip Gibson

School of Natural Resources: Dissertations, Theses, and Student Research

Given current and continued investment in irrigation scheduling technologies, a need exists to better estimate the longevity and magnitude of water savings at watershed level to avoid the paradox of irrigation efficiency. This paradox occurs within a watershed as not all irrigation inefficiencies lead to the system losing water. For example, irrigation pumping rates in excess of crop water demand may lead to enhanced groundwater recharge or surface runoff that migrates to a stream. Thus, increases in efficiency may not lead to similar magnitudes of water savings. I hypothesize that water savings longevities are short given previous work demonstrating rapid …

Postseismic Restoration Of The Ecological Environment In The Wenchuan Region Using Satellite Data, Zhibin Huang, Min Xu, Wei Chen, Xiaojuan Lin, Chunxiang Cao, Ramesh Singh

Mathematics, Physics, and Computer Science Faculty Articles and Research

Using Landsat remote-sensing data combined with geological information extracted from ALOS and Sentinel-1A radar data, the ecological environment was evaluated in the years 2007, 2008, 2013, and 2017 through gray correlation analysis on the basis of the construction of the pressure-state-response model. The main objective of this research was to assess the ecological environment changes in Wenchuan County before and after the earthquake, and to provide reference for future social development and policy implementation. The grading map of the ecological environment was obtained for every year, and the ecological restoration status of Wenchuan County after the earthquake was evaluated. The …

Using Carbon Isotope Fractionation To Constrain The Extent Of Methane Dissolution Into The Water Column Surrounding A Natural Hydrocarbon Gas Seep In The Northern Gulf Of Mexico, M. Leonte, B. Wang, Scott A. Socolofsky, John A. Breier, John D. Kessler

School of Earth, Environmental, & Marine Sciences Faculty Publications

A gas bubble seep located in the northern Gulf of Mexico was investigated over several days to determine whether changes in the stable carbon isotopic ratio of methane can be used as a tracer for methane dissolution through the water column. Gas bubble and water samples were collected at the seafloor and throughout the water column for isotopic ratio analysis of methane. Our results show that changes in methane isotopic ratios are consistent with laboratory experiments that measured the isotopic fractionation from methane dissolution. A Rayleigh isotope model was applied to the isotope data to determine the fraction of methane …

Mesobot : An Autonomous Underwater Vehicle For Tracking And Sampling Midwater Targets, Dana R. Yoerger, Molly Curran, Justin Fujii, Christopher R. German, Daniel Gomez-Ibanez, Annette F. Govindarajan, Jonathan C. Howland, Joel K. Llopiz, Peter H. Wiebe, Brett W. Hobson, Kakani Katija, Michael Risi, Bruce H. Robison, Cailean J. Wilkinson, Stephen M. Rock, John A. Breier

School of Earth, Environmental, & Marine Sciences Faculty Publications

Mesobot, a new class of autonomous underwater vehicle, will address specific unmet needs for observing slow-moving targets in the midwater ocean. Mesobot will track targets such as zooplankton, fish, and descending particle aggregates using a control system based on stereo cameras and a combination of thrusters and a variable buoyancy system. The vehicle will also be able to collect biogeochemical and environmental DNA (eDNA) samples using a pumped filter sampler.

Remote Estimation Of Surface Water PCo2 In The Gulf Of Mexico, Shuangling Chen

USF Tampa Graduate Theses and Dissertations

Surface ocean partial pressure of CO₂ (pCO₂) is a critical parameter in the quantification of air-sea CO₂ flux, which further plays an important role in quantifying the global carbon budget and understanding ocean acidification. The demand for a clearer understanding of how, and how fast, the ocean is changing due to atmospheric CO₂ absorption, requires accurate and synoptic estimation of surface pCO₂.

Surface ocean pCO₂ is mainly controlled by four oceanic processes – thermodynamics, ocean mixing, biological activities, and air-sea CO₂ exchange. Surface ocean pCO_{2 …}

Ice And Guano Deposits In El Malpais Lava Tubes: Potential Paleoclimate Archives For The Southwest United States, Dylan S. Parmenter

USF Tampa Graduate Theses and Dissertations

Three ice cores and one guano core were obtained from lava tubes in El Malpais National Monument, New Mexico, in the Southwest United States. A large hiatus in the Bat Cave guano record, resulting from mining activities in the early 1900's, left us with only ~50 years of data (from AD 1955-2006) to use in analysis. 13C values in guano (-18 to -11.6‰) primarily fall within the range of C4 plants, and likely indicate a tendency of Tadarida brasiliensis to feed on insects over grasslands to the North or South of the park. Variations in 13C values for this period …

Managing Risk In Grazing Operations, Christopher D. Teutsch, Kenneth H. Burdine

Kentucky Grazing Conference

Risk is an inherent part of agricultural production systems. Crane and coworkers (2013) identified five primary areas of risk in grazing operations: 1) MARKETING risk, 2) PRODUCTION risk, 3) LEGAL risk, 4) HUMAN risk, and FINANCIAL risk. These types of risk are described in the accompanying publication entitled “Controlling Risk in Grazing-Based Production Systems” by J. Parsons. This article will discuss the risk associated with “production” in grazing systems, focusing specifically on managing drought in grass based production operations.

Lake Surface Water Temperature Change Over The Tibetan Plateau From 2001 To 2015a Sensitive Indicator Of The Warming Climate, W. Wan, L. Zhao, H. Xie, B. Liu, H. Li, Ying Cui, Yan Ma

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The Tibetan Plateau (TP) plays a significant role in the Earth's climate system. This letter examines the nighttime lake surface water temperature (LSWT) of 374 lakes (≥10 km 2 each) over the TP for the past 15 years (2001–2015). An overall warming trend (0.037 °C/year) is found and it is consistent with the warming air temperature (0.036 °C/year) over the TP, with the vast majority of the lakes (70%, with 28% of which are significant) showing warming (0.076 °C/year) and the rest (30%, with 37% of which are significant) showing cooling (−0.053 °C/year). This astonishing contrast was controlled by different …

A Novel Shortwave Infrared Proximal Sensing Approach To Quantify The Water Stability Of Soil Aggregates, Azadeh Gholoubi, Hojat Emami, Scott B. Jones, Markus Tuller

Plants, Soils, and Climate Faculty Publications

Soil structure and aggregate stability (AS) are critical soil properties affecting water infiltration, root growth, and resistance to soil and wind erosion. Changes in AS may be early indicators of soil degradation, pointing to low organic matter (OM) content, reduced biological activity, or poor nutrient cycling. Hence, efficient and reliable AS measurement techniques are essential for detection, management, and remediation of degraded soil resources. Here we quantify soil AS by developing a novel proximal sensing technique based on shortwave infrared (SWIR) reflectance measurements. The novel approach is similar to the well-documented high energy moisture characteristic (HEMC) method, which yields a …

The Sedimentology And Origins Of A Giant Mass Transport Complex: The Nataraja Slide, Arabian Sea, Sarah Dailey

LSU Master's Theses

A giant mass transport complex (MTC) was recently discovered in the eastern Arabian Sea exceeding in volume all but one other known complex on passive margins worldwide. The complex, named the Nataraja Slide, was drilled by IODP Expedition 355 in two locations where it is ~300 m (Site U1456) and ~200 m thick (Site U1457). The top is defined by the presence of both reworked microfossil assemblages and deformation structures, such as folding and faulting. The deposit consists of two main phases of mass wasting, each which consists of smaller pulses, with generally fining upward cycles, all emplaced just prior …

Theory On Thermodynamic Constraints To Biogeochemical And Metabolic Diversity, Jordan Okie, Everett Shock

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Nutrient Addition And Drought Interact To Change The Structure And Decrease The Functional Diversity Of A Mediterranean Grassland, Carla Nogueira, Alice Nunes, Miguel N. Bugalho, Cristina Branquinho, Rebecca L. Mcculley, Maria Conceição Caldeira

Plant and Soil Sciences Faculty Publications

Anthropogenic activities are increasing nutrient availability and altering precipitation regimes. This may lead to critical changes in grasslands functioning. This is particularly important for grasslands in the Mediterranean Basin that have evolved in nutrient poor soils, and where more frequent and prolonged droughts are projected to occur. However, there is limited knowledge regarding the interacting effects of multiple nutrient inputs and rainfall variability on the plant functional structure and diversity of Mediterranean grasslands. We conducted a nutrient addition experiment in a Mediterranean grassland during four contrasting precipitation years. We established four treatments that varied in the number of added nutrients, …

On Biospeleothems From A Venezuelan Tepui Cave: U-Th Dating, Growth Rates, And Morphology, Joyce Lundberg, Charles Brewer-Carías, Donald A. Mcfarlane

International Journal of Speleology

Seven silica biospeleothems from Cueva Charles Brewer, Chimantá Plateau, Venezuela have been successfully U-Th dated despite very low U and high detrital Th concentrations. Growth rates are low, between ~100 to ~800 µm/ka, and are greater closer to water level. Dates in unaltered material are in good stratigraphic order, but secondary silicification may compromise the U-Th system, yielding unreliable sequences of ages. Detritally-enriched layers correlate with global climate cycles of the Late Quaternary, in particular the cooler, drier phases of MIS 5d, 5a, and 4. SEM studies indicate that the peloidal material is made up of silica nano-particles assembled to …

Detection, Occurrence And Fate Of Emerging Contaminants In Agricultural Environments, Daniel D. Snow, David A. Cassada, Saptashati Biswas, Mohammedreza Shafieifini, Xu Li, Matteo D'Alessio, Laura Carter, J. Brett Sallach

Daugherty Water for Food Global Institute: Faculty Publications

A total of 75 papers published in 2017 were reviewed ranging from detailed descriptions of analytical methods, to fate and occurrence studies, to ecological effects and sampling techniques for a wide variety of emerging contaminants likely to occur in agricultural environments. New methods and studies on veterinary pharmaceuticals, steroids, antibiotic resistance genes, and engineered nanoparticles agricultural environments continue to expand our knowledge base on the occurrence and potential impacts of these compounds. This review is divided into the following sections: Introduction, Analytical Methods, Fate and Occurrence, Pharmaceutical Metabolites, Anthelmintics, Antibiotic Resistance Genes, and Engineered Nanomaterials.