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Articles 5371 - 5400 of 13997

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

The Spectral And Chemical Measurement Of Pollutants On Snow Near South Pole, Antarctica, Kimberly A. Casey, Susan D. Kaspari, S. M. Skiles, K. Kreutz, M. J. Handley Jun 2017

The Spectral And Chemical Measurement Of Pollutants On Snow Near South Pole, Antarctica, Kimberly A. Casey, Susan D. Kaspari, S. M. Skiles, K. Kreutz, M. J. Handley

All Faculty Scholarship for the College of the Sciences

Remote sensing of light-absorbing particles (LAPs), or dark colored impurities, such as black carbon (BC) and dust on snow, is a key remaining challenge in cryospheric surface characterization and application to snow, ice, and climate models. We present a quantitative data set of in situ snow reflectance, measured and modeled albedo, and BC and trace element concentrations from clean to heavily fossil fuel emission contaminated snow near South Pole, Antarctica. Over 380 snow reflectance spectra (350–2500 nm) and 28 surface snow samples were collected at seven distinct sites in the austral summer season of 2014–2015. Snow samples were analyzed for …


Improved Atmospheric Characterization For Hyperspectral Exploitation, Nathan P. Wurst Jun 2017

Improved Atmospheric Characterization For Hyperspectral Exploitation, Nathan P. Wurst

Theses and Dissertations

Airborne hyperspectral imaging (HSI) in the LWIR has shown utility in material detection and identification. This research seeks to determine the most effective methods to perform model-based atmospheric compensation of LWIR HSI data by comparing results obtained from different atmospheric profiles. The standard model for mid-latitude summer (MLS) and radiosonde data are compared to the National Operational Model Archive and Distribution System (NOMADS) numerical weather predictions and the Extreme and Percentile Environmental Reference Tables (ExPERT). The two latter atmospheric profiles are generated using the Laser Environmental Effects Definition and Reference (LEEDR) software. MLS has been a standard starting point for …


Economic Evaluation Of Coastal Land Loss In Louisiana, Stephen R. Barnes, Craig Bond, Nicholas Burger, Kate Anania, Aaron Strong, Sarah Weilant, Stephanie Virgets Jun 2017

Economic Evaluation Of Coastal Land Loss In Louisiana, Stephen R. Barnes, Craig Bond, Nicholas Burger, Kate Anania, Aaron Strong, Sarah Weilant, Stephanie Virgets

Journal of Ocean and Coastal Economics

Louisiana has lost approximately 1,880 square miles of land over the past eighty years. Projections suggest that in a future without action, the next fifty years could result in the loss of 1,750 additional square miles of land area. As land loss continues, a large portion of the natural and man-made capital stocks of coastal Louisiana will be at greater risk of damage, either from land loss or from the associated increase in storm damage. We estimate the replacement cost of capital stock directly at risk from land loss ranges from approximately $2.1 billion to $3.5 billion with economic activity …


Integrating Future Scenario-Based Crop Expansion And Crop Conditions To Map Switchgrass Biofuel Potential In Eastern Nebraska, Usa, Yingxin Gu, Bruce K. Wylie Jun 2017

Integrating Future Scenario-Based Crop Expansion And Crop Conditions To Map Switchgrass Biofuel Potential In Eastern Nebraska, Usa, Yingxin Gu, Bruce K. Wylie

United States Geological Survey: Staff Publications

Switchgrass (Panicum virgatum) has been evaluated as one potential source for cellulosic biofuel feedstocks. Planting switchgrass in marginal croplands and waterway buffers can reduce soil erosion, improve water quality, and improve regional ecosystem services (i.e. it serves as a potential carbon sink). In previous studies, we mapped high risk marginal croplands and highly erodible cropland buffers that are potentially suitable for switchgrass development, which would improve ecosystem services and minimally impact food production. In this study, we advance our previous study results and integrate future crop expansion information to develop a switchgrass biofuel potential ensemble map for current and future …


First Na Lidar Measurements Of Turbulence Heat Flux, Thermal Diffusivity, And Energy Dissipation Rate In The Mesopause Region, Yafang Guo, Alan Z. Liu, Chester S. Gardner Jun 2017

First Na Lidar Measurements Of Turbulence Heat Flux, Thermal Diffusivity, And Energy Dissipation Rate In The Mesopause Region, Yafang Guo, Alan Z. Liu, Chester S. Gardner

Publications

Turbulence is ubiquitous in the mesopause region, where the atmospheric stability is low and wave breaking is frequent. Measuring turbulence is challenging in this region and is traditionally done by rocket soundings and radars. In this work, we show for the first time that the modern Na wind/temperature lidar located at Andes Lidar Observatory in Cerro Pachón, Chile, is able to directly measure the turbulence perturbations in temperature and vertical wind between 85 and 100 km. Using 150 h of lidar observations, we derived the frequency (ω) and vertical wave number (m) spectra for both gravity …


Lichen Conservation In Eastern North America: Population Genomics, Climate Change, And Translocations, Jessica Allen Jun 2017

Lichen Conservation In Eastern North America: Population Genomics, Climate Change, And Translocations, Jessica Allen

Dissertations, Theses, and Capstone Projects

Conservation biology is a scientific discipline that draws on methods from diverse fields to address specific conservation concerns and inform conservation actions. This field is overwhelmingly focused on charismatic animals and vascular plants, often ignoring other diverse and ecologically important groups. This trend is slowly changing in some ways; for example, increasing number of fungal species are being added to the IUCN Red-List. However, a strong taxonomic bias still exists. Here I contribute four research chapters to further the conservation of lichens, one group of frequently overlooked organisms. I address specific conservation concerns in eastern North America using modern methods. …


Umphlett Qci June 2017, Natalie Umphlett Jun 2017

Umphlett Qci June 2017, Natalie Umphlett

High Plains Regional Climate Center: Staff Publications

Highlights for the Basin

Temperature and Precipitation Anomalies

Snowpack and Streamflow

Historic Flooding in Missouri

Spring Conditions Impact Agriculture

3-Month Precipitation and Temperature Outlooks

U.S. Seasonal Drought Outlook


Sensitivity Of Conus Summer Rainfall To The Selection Of Cumulus Parameterization Schemes In Nu-Wrf Seasonal Simulations, Takamichi Iguchi, Wei-Kuo Tao, Di Wu, Christa D. Peters-Lidard, Joseph A. Santanello, Eric Kemp, Yudong Tian, Jonathan Case, Weile Wang, Robert Ferraro, Duane E. Waliser, Jinwon Kim, Huikyo Lee, Bin Guan, Baijun Tian, Paul C. Loikith Jun 2017

Sensitivity Of Conus Summer Rainfall To The Selection Of Cumulus Parameterization Schemes In Nu-Wrf Seasonal Simulations, Takamichi Iguchi, Wei-Kuo Tao, Di Wu, Christa D. Peters-Lidard, Joseph A. Santanello, Eric Kemp, Yudong Tian, Jonathan Case, Weile Wang, Robert Ferraro, Duane E. Waliser, Jinwon Kim, Huikyo Lee, Bin Guan, Baijun Tian, Paul C. Loikith

Geography Faculty Publications and Presentations

This study investigates the sensitivity of daily rainfall rates in regional seasonal simulations over the contiguous United States (CONUS) to different cumulus parameterization schemes. Daily rainfall fields were simulated at 24-km resolution using the NASA-Unified Weather Research and Forecasting (NU-WRF) Model for June–August 2000. Four cumulus parameterization schemes and two options for shallow cumulus components in a specific scheme were tested. The spread in the domain-mean rainfall rates across the parameterization schemes was generally consistent between the entire CONUS and most subregions. The selection of the shallow cumulus component in a specific scheme had more impact than that of the …


Comment On "Using An Adcp To Estimate Turbulent Kinetic Energy Dissipation Rate In Sheltered Coastal Waters", Ann E. Gargett Jun 2017

Comment On "Using An Adcp To Estimate Turbulent Kinetic Energy Dissipation Rate In Sheltered Coastal Waters", Ann E. Gargett

CCPO Publications

Greene et al. revisit the suggestion that the turbulent kinetic energy dissipation rate could be estimated through a "large-eddy estimate," employing acoustic measurements of velocity fields associated with the largest energy-containing scales of ocean turbulence. While the large-eddy estimate as originally proposed used vertical velocity and a vertical eddy length scale, Greene et al. chose instead to substitute a horizontal length scale for the latter. This comment argues that combining a horizontal scale for length with a vertical velocity scale produces a large-eddy estimate of the dissipation rate that is accurate only if the energy-containing eddies are isotropic, and that …


Micro-Spi Sediment Profile Imaging Micro-Inspector, Andrew P. Corvin, Caleb T. Davies, Matt R. Ferrari Jun 2017

Micro-Spi Sediment Profile Imaging Micro-Inspector, Andrew P. Corvin, Caleb T. Davies, Matt R. Ferrari

Mechanical Engineering

This project was proposed by Dr. Brian Paavo through a desire to more easily study the benthic sediment layers of the ocean. To do so, he asked us to build a simple and compact machine for use in sediment profile imagery (SPI). Although devices like this already exist, they are all large scale devices that require a ship with a crane to deploy, which is expensive and time consuming. Instead, he desired a “micro” SPI, which is capable of being deployed from a small vessel that can easily navigate shallow waters. Our interpretation of these requirements was as follows: a …


Depletion Of Ozone And Reservoir Species Of Chlorine And Nitrogen Oxide In The Lower Antarctic Polar Vortex Measured From Aircraft, T. Jurkat, C. Voigt, S. Kaufmann, J.-U. Grooß, H. Ziereis, A. Dörnbrack, P. Hoor, H. Bozem, A. Engel, H. Bönisch, P. F. Bernath Jun 2017

Depletion Of Ozone And Reservoir Species Of Chlorine And Nitrogen Oxide In The Lower Antarctic Polar Vortex Measured From Aircraft, T. Jurkat, C. Voigt, S. Kaufmann, J.-U. Grooß, H. Ziereis, A. Dörnbrack, P. Hoor, H. Bozem, A. Engel, H. Bönisch, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Novel airborne in situ measurements of inorganic chlorine, nitrogen oxide species, and ozone were performed inside the lower Antarctic polar vortex and at its edge in September 2012. We focus on one flight during the Transport and Composition of the LMS/Earth System Model Validation (TACTS/ESMVal) campaign with the German research aircraft HALO (High-Altitude LOng range research aircraft), reaching latitudes of 65°S and potential temperatures up to 405 K. Using the early winter correlations of reactive trace gases with N2O from the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), we find high depletion of chlorine reservoir gases up to ∼40% …


The Ocean's Vital Skin: Toward An Integrated Understanding Of The Sea Surface Microlayer, Anja Engel, Hermann W. Bange, Michael Cunliffe, Susannah M. Burrows, Gernot Friedrichs, Luisa Galgani, Hartmut Herrmann, Norbert Hertkorn, Martin Johnson, Peter S. Liss, Patrick K. Quinn, Markus Schartau, Alexander Soloviev, Christian Stolle, Robert C. Upstill-Goddard, Manuela Van Pinxteren, Birthe Zäncker May 2017

The Ocean's Vital Skin: Toward An Integrated Understanding Of The Sea Surface Microlayer, Anja Engel, Hermann W. Bange, Michael Cunliffe, Susannah M. Burrows, Gernot Friedrichs, Luisa Galgani, Hartmut Herrmann, Norbert Hertkorn, Martin Johnson, Peter S. Liss, Patrick K. Quinn, Markus Schartau, Alexander Soloviev, Christian Stolle, Robert C. Upstill-Goddard, Manuela Van Pinxteren, Birthe Zäncker

Marine & Environmental Sciences Faculty Articles

Despite the huge extent of the ocean's surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean's surface, in particular involving …


The Effect Of Watershed Runoff And Sediment Resuspension On Turbidity And Sediment Deposition In St. John, Us Virgin Islands: Implications For Watershed And Marine Development And Restoration In Bays With Coral Reefs, Stephen E. Campbell May 2017

The Effect Of Watershed Runoff And Sediment Resuspension On Turbidity And Sediment Deposition In St. John, Us Virgin Islands: Implications For Watershed And Marine Development And Restoration In Bays With Coral Reefs, Stephen E. Campbell

Theses

In the US Virgin Islands (USVI), land-based (terrigenous) sedimentation has been identified as a major cause of coral stress. Development, such as the building of unpaved roads in steep coastal watersheds, has increased sediment yields and marine terrigenous sedimentation by up to an order of magnitude above background levels. When activated during storm events, ephemeral streams transport sediment from the watershed to coastal waters. Once deposited on the seafloor, resuspension of benthic sediments can further increase turbidity and deposition. However, isolating the relative contributions of runoff and resuspension to turbidity and deposition using conventional sediment trap monitoring has been challenging. …


The Indianapolis Flux Experiment (Influx): A Test-Bed For Developing Urban Greenhouse Gas Emission Measurements, Kenneth J. Davis, Aijun Deng, Thomas Lauvaux, Natasha Miles, Scott Richardson, Daniel Sarmiento, Kevin R. Gurney, R Michael Hardesty, Timothy A. Bonin, W Alan Brewer, Brian K. Lamb, Paul B. Shepson, Rebecca M. Harvey, Maria Obiminda L. Cambaliza, Colm Sweeney, Jocelyn Turnbull, James Whetstone, Anna Karion May 2017

The Indianapolis Flux Experiment (Influx): A Test-Bed For Developing Urban Greenhouse Gas Emission Measurements, Kenneth J. Davis, Aijun Deng, Thomas Lauvaux, Natasha Miles, Scott Richardson, Daniel Sarmiento, Kevin R. Gurney, R Michael Hardesty, Timothy A. Bonin, W Alan Brewer, Brian K. Lamb, Paul B. Shepson, Rebecca M. Harvey, Maria Obiminda L. Cambaliza, Colm Sweeney, Jocelyn Turnbull, James Whetstone, Anna Karion

Physics Faculty Publications

The objective of the Indianapolis Flux Experiment (INFLUX) is to develop, evaluate and improve methods for measuring greenhouse gas (GHG) emissions from cities. INFLUX’s scientific objectives are to quantify CO2 and CH4 emission rates at 1 km2 resolution with a 10% or better accuracy and precision, to determine whole-city emissions with similar skill, and to achieve high (weekly or finer) temporal resolution at both spatial resolutions. The experiment employs atmospheric GHG measurements from both towers and aircraft, atmospheric transport observations and models, and activity-based inventory products to quantify urban GHG emissions. Multiple, independent methods for estimating urban emissions are a …


Coral Larvae Are Poor Swimmers And Require Fine-Scale Reef Structure To Settle, Tom Hata, Joshua S. Madin, Vivian R. Cumbo, Mark W. Denny, Joana Figueiredo, Saki Harii, Christopher J. Thomas, Andrew H. Baird May 2017

Coral Larvae Are Poor Swimmers And Require Fine-Scale Reef Structure To Settle, Tom Hata, Joshua S. Madin, Vivian R. Cumbo, Mark W. Denny, Joana Figueiredo, Saki Harii, Christopher J. Thomas, Andrew H. Baird

Marine & Environmental Sciences Faculty Articles

Reef coral assemblages are highly dynamic and subject to repeated disturbances, which are predicted to increase in response to climate change. Consequently there is an urgent need to improve our understanding of the mechanisms underlying different recovery scenarios. Recent work has demonstrated that reef structural complexity can facilitate coral recovery, but the mechanism remains unclear. Similarly, experiments suggest that coral larvae can distinguish between the water from healthy and degraded reefs, however, whether or not they can use these cues to navigate to healthy reefs is an open question. Here, we use a meta-analytic approach to document that coral larval …


Proposed Legislation Seeks To Stimulate Investment In Coastal Resiliency, Jon Cawley May 2017

Proposed Legislation Seeks To Stimulate Investment In Coastal Resiliency, Jon Cawley

News Items

No abstract provided.


Strong Linkages Between Surface And Deep-Water Dissolved Organic Matter In The East/Japan Sea, Tae-Hoon Kim, Guebuem Kim, Yuan Shen, Ronald Benner May 2017

Strong Linkages Between Surface And Deep-Water Dissolved Organic Matter In The East/Japan Sea, Tae-Hoon Kim, Guebuem Kim, Yuan Shen, Ronald Benner

Faculty Publications

Vertical and horizontal distributions of total dissolved amino acids (TDAAs), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) were measured in the East/Japan Sea (EJS). The euphotic zone of this sea is N-limited, and the N : P ratio is ∼ 13 below 200 m depth. Elevated TDAA concentrations (137 ± 34 nM) and DOC-normalized yields (0.8 ± 0.2 % of DOC) were observed in deep waters ( ≥  1000 m) of the EJS and compared with those in the deep North Pacific Ocean. Significantly high TDAA concentrations and yields were observed in a region of deep-water formation, indicating …


Larval Rockfish Diversity Abundance Dynamics In Association With A Marine Protected Area In The Southern California Bight, Dustin Chen May 2017

Larval Rockfish Diversity Abundance Dynamics In Association With A Marine Protected Area In The Southern California Bight, Dustin Chen

Theses

Marine protected areas (MPAs) are areas aimed at protecting natural and cultural resources that are often proposed as a way to alleviate the effects of overfishing on populations of targeted species; these areas have varying degrees of fishing and recreational use restrictions. In order to assess MPA efficacy, it is important to determine the mechanisms by which the presence of MPAs affect reproductive output within and potentially even beyond their boundaries. I attempted to address this through studying the responses of rockfish (Sebastes spp.) larval abundances to the presence of the Cowcod Conservation Areas (CCAs) located within the Southern California …


Use Of First Pelvic, Second Pelvic, And Fourth Anal Rays For Estimating Age Of Muskellunge (Esox Masquinongy), Marinda R. Cornett May 2017

Use Of First Pelvic, Second Pelvic, And Fourth Anal Rays For Estimating Age Of Muskellunge (Esox Masquinongy), Marinda R. Cornett

Honors Theses

While cleithra are the most popularly used calcified structure used to estimate age of Muskellunge (Esox masquinongy), the use of fin rays as an age estimation structure has been investigated as a nonlethal alternative. My objectives were to: (1) to compare the accuracy and precision of estimating age using first pelvic, second pelvic, and fourth anal rays from 46 known age Muskellunge and (2) to analyze a larger sample (n = 120) of fourth anal rays to estimate age. Ages were estimated blindly by three readers independently from all available structures. Different analyses of precision and accuracy had conflicting results, …


A Multibeam Bathymetric Investigation Of Changes In Bedform Morphology Of The Little River Inlet As A Result Of Hurricane Matthew, Malarie O'Brien May 2017

A Multibeam Bathymetric Investigation Of Changes In Bedform Morphology Of The Little River Inlet As A Result Of Hurricane Matthew, Malarie O'Brien

Honors Theses

A hybrid scholarly-research paper on the use of multibeam sonar data in seafloor mapping and seafloor analysis was written to satisfy Honors Program requirements. Literature review of multibeam sonar technology explored the improving concept of mapping the seafloor via acoustic methods. The review also investigated improvements and applications of multibeam data analysis techniques, which have the ability to map the seafloor as well as characterize the seafloor by morphology or sediment content. The review then explored previous studies conducted on the Little River Inlet, SC, finding the inlet to be particularly understudied in the field of sediment morphology. Three multibeam …


Variable Patterns In Spur And Groove Reef Morphology Explained By Physical Controls And Their Relevance For Platform-Top Sedimentology, Robert C. Gardiner Jr May 2017

Variable Patterns In Spur And Groove Reef Morphology Explained By Physical Controls And Their Relevance For Platform-Top Sedimentology, Robert C. Gardiner Jr

HCNSO Student Theses and Dissertations

Spur and groove (SaG) morphology is a common ornamentation of reef-armored Holocene carbonate platform margins. Composed of margin-normal promontories constructed of coral framestone, termed “spurs”, interleaved with similarly orientated gullies, “grooves”, this morphology varies based on a host of physical controls. Primarily, the surrounding oceanographic conditions as well as the size and shape of the platform the SaG is encompassing, directly influence the development and organization of SaG. Since grooves act as conduits for carbonate sediment transport, this study seeks to examine the relationship between SaG organization dictated by platform size and shape and how that in turn influences platform-top …


The Arctic: Science, Law, And Policy, Charles H. Norchi, Paul A. Mayewski May 2017

The Arctic: Science, Law, And Policy, Charles H. Norchi, Paul A. Mayewski

Ocean and Coastal Law Journal

In 1959, Sir Charles Snow (C.P. Snow) delivered a lecture at Cambridge University entitled The Two Cultures and the Scientific Revolution in which he identified a duality of cultures. There were the scientists and the humanists--two dimly acquanited cultures that rarely communicated, and when they did it was usually at cross-purposes. One culture was contentedly unknowing and skeptical of science, and the other was marginal to the great social questions of the time. For C.P. Snow, the polarization and lack of communication between the two groups could be fatal to the Western World. The 21st century has also revealed polarized …


Forecasted Range Shifts Of Arid-Land Fishes In Response To Climate Change, James E. Whitney, Joanna B. Whittier, Craig Patrick Paukert, Julian D. Olden, Angela L. Strecker May 2017

Forecasted Range Shifts Of Arid-Land Fishes In Response To Climate Change, James E. Whitney, Joanna B. Whittier, Craig Patrick Paukert, Julian D. Olden, Angela L. Strecker

Environmental Science and Management Faculty Publications and Presentations

Climate change is poised to alter the distributional limits, center, and size of many species. Traits may influence different aspects of range shifts, with trophic generality facilitating shifts at the leading edge, and greater thermal tolerance limiting contractions at the trailing edge. The generality of relationships between traits and range shifts remains ambiguous however, especially for imperiled fishes residing in xeric riverscapes. Our objectives were to quantify contemporary fish distributions in the Lower Colorado River Basin, forecast climate change by 2085 using two general circulation models, and quantify shifts in the limits, center, and size of fish elevational ranges according …


An Evaluation Of Gridded Temperature Products And Their Effectiveness In Modeling Small Scale Ambient Temperature, Barrie Chileen May 2017

An Evaluation Of Gridded Temperature Products And Their Effectiveness In Modeling Small Scale Ambient Temperature, Barrie Chileen

Celebration of Learning

The use of gridded temperature products is becoming increasingly prevalent in ecological research due to their accessibility, low cost, and spatial and temporal coverage. While a few studies have compared gridded products against each other and against weather station data, little research exists that attempts to verify the accuracy of these gridded products on finer spatial scales in field settings. In this study, we use two networks of temperature sensors to evaluate the effectiveness of these widely used gridded products in modeling ambient temperatures and compare tradeoffs between spatial and temporal resolution of gridded products.

We deployed 65 temperature sensors …


Concentrations And Size Distributions Of Bacteria-Containing Particles Over Oceans From China To The Arctic Ocean, Ming Li, Xiawei Yu, Hui Kang, Zhouqing Xie, Pengfei Zhang May 2017

Concentrations And Size Distributions Of Bacteria-Containing Particles Over Oceans From China To The Arctic Ocean, Ming Li, Xiawei Yu, Hui Kang, Zhouqing Xie, Pengfei Zhang

Publications and Research

During the third China Arctic Research Expedition (July–September 2008), size-resolved measurements of bacteria-containing particles (BCPs) in the marine boundary layer (MBL) air were conducted during a cruise through the East China Sea, the Yellow Sea, the Japan Sea, the Okhotsk Sea, the Bering Sea, the Chukchi Sea, and the Arctic Ocean. The concentrations of total airborne BCPs (TBCPs), non-salt tolerant airborne BCPs (NSBCPs), and salt tolerant airborne BCPs (SBCPs) varied from 29 to 955 CFU m − 3 (CFU = Colony Forming Unit), 16 to 919 CFU m − 3 , and 4 to 276 CFU m − 3 , …


Do Halogenated Natural Products Bioaccumulate In Narragansett Bay?, Christine Gardiner, Anna Robuck, Rainer Lohmann May 2017

Do Halogenated Natural Products Bioaccumulate In Narragansett Bay?, Christine Gardiner, Anna Robuck, Rainer Lohmann

Senior Honors Projects

In recent decades, a new family of chemical compounds has begun to garner research attention—halogenated natural products, or HNPs. These chemicals are produced by algae, bacteria, worms, and sponges, and many are structurally similar to harmful manmade compounds, such as polychlorinated diphenyls (PCBs), or brominated flame retardants (PBDEs), which are known to cause cancer, reproduction issues, endocrine disruption, and death. While HNPs are produced naturally, they are still considered pollutants because of their bioaccumulative behavior and apparent toxicity.

Currently, there is limited research on their presence and effects, with a few studies from Europe and the Pacific highlighting their importance …


Understanding N-Nitrosodimethylamine Formation In Water: Chloramine Chemistry, Kinetics, And A Proposed Reaction Pathway, Huong Thu Pham May 2017

Understanding N-Nitrosodimethylamine Formation In Water: Chloramine Chemistry, Kinetics, And A Proposed Reaction Pathway, Huong Thu Pham

Graduate Theses and Dissertations

The formation of N-nitrosodimethylamine (NDMA) in drinking water systems is a concern because of its potential carcinogenicity and occurrence at toxicologically relevant levels. The postulated mechanism for NDMA formation involves a substitution between dichloramine and amine-based precursors to form an unsymmetrical dimethylhydrazine (UDMH), which is then oxidized by ground-state molecular oxygen to form NDMA. However, this latter reaction is spin forbidden, thus likely occurs at a slow rate. It is hypothesized that the reaction between monochloramine and hydroxylamine (a nitrification product) may form an intermediate, which is involved in the NDMA formation pathway. This intermediate may also be generated from …


The Role Of Sulfur Dioxide In Stratospheric Aerosol Formation Evaluated By Using In Situ Measurements In The Tropical Lower Stratosphere, A. W. Rollins, T. D. Thornberry, L. A. Watts, P. Yu, K. H. Rosenlof, M. Mills, E. Baumann, F. R. Giorgetta, T. V. Bui, M. Höpfner, P. F. Bernath May 2017

The Role Of Sulfur Dioxide In Stratospheric Aerosol Formation Evaluated By Using In Situ Measurements In The Tropical Lower Stratosphere, A. W. Rollins, T. D. Thornberry, L. A. Watts, P. Yu, K. H. Rosenlof, M. Mills, E. Baumann, F. R. Giorgetta, T. V. Bui, M. Höpfner, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Stratospheric aerosols (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (geoengineering). The role of tropospheric-sourced sulfur dioxide (SO2) in maintaining background SAs has been debated for decades without in situ measurements of SO2 at the tropical tropopause to inform this issue. Here we clarify the role of SO2 in maintaining SAs by using new in situ SO2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO2 mixing ratios to estimate the global flux of …


Ecological Importance Of Invader Source Population And Disturbance In Aquatic Invasions, Nicole Elizabeth Graham May 2017

Ecological Importance Of Invader Source Population And Disturbance In Aquatic Invasions, Nicole Elizabeth Graham

Graduate Theses and Dissertations

Invasive species are a global problem and their effects on recipient ecosystems may be mediated by disturbance and intraspecific variation. Crayfish can substantially influence stream structure and function, and invasive crayfish often have differential impacts than native crayfish in aquatic ecosystems. Since species traits often vary across a distribution, it is possible that invasive crayfish from different source populations may have distinct impacts on recipient ecosystem structure and function. In the Ozark Highlands of Arkansas and Missouri, USA, invasive O. neglectus (the Ringed Crayfish) may be leading to the displacement of native O. eupunctus (the Coldwater Crayfish). The objective of …


Ab Initio Computation Of Radiative Properties Of Monatomic Hydrogen, Fanny Thomas May 2017

Ab Initio Computation Of Radiative Properties Of Monatomic Hydrogen, Fanny Thomas

Doctoral Dissertations and Master's Theses

With renewed interest in planetary atmospheric entry, descent, and landing, NASA has noted a need for improved physics modeling in computational fluid dynamics. Uncertainty in experimental data used in radiation heat transfer computations leads to “over-engineering” of entry body heat shields, at large weight and cost penalties. There is interest in developing hypersonic thermophysics models from the known “first principles” of physics.

A method for computing high temperature gas emissivity and absorptivity from quantum mechanics principles is developed. The Schroedinger wave equation is cast as a discretized matrix eigenvalue problem which is solved using the ERAU parallel supercomputer. The numerical …