Oceanography and Atmospheric Sciences and Meteorology Commons^™

Applied Depositional Geosystems Of The Coos Bay Basin, Oregon: Organic Geochemistry, Maturation, Paleoenvironmental Reconstruction And Biostratigraphy Of The Coaledo Delta During The Middle Eocene Climatic Optimum (Meco), Allison K. Barbato

LSU Doctoral Dissertations

The Coos Bay Basin on the southwestern coast of Oregon is a forearc basin that contains exceptionally preserved Eocene to Miocene, tidal to wave-dominated, shallow deltaic to deep marine sediments of the Coaledo Delta. Coastal depositional environments are known to host source, reservoir, and seal rocks. Climate, topographic relief, and geographical position all play an important role in regional vegetation development and oceanic setting. This study assesses 84 outcrop and 12 core samples from Coos Bay for their organic geochemical characteristics and microfossil assemblage to provide source rock characterization information, organofacies descriptions, environmental reconstructions, and age control.

Results indicate the …

Uncovering Chimborazo’S Catchments: Insights Into The Fluvial Network, Stream Characteristics, And Hydrological Patterns In Reserva De Producción De Fauna Chimborazo, Ecuador, Julia L. Schwartz

Independent Study Project (ISP) Collection

Andean headwater streams play a crucial role in the provisioning of ecosystem services and supplying water to downstream communities. This study sought to analyze trends in hydrological patterns in the páramo of the southwestern aspect of Volcán Chimborazo in central Ecuador, as well as to provide a more complete survey of the fluvial network given the lack of existing data and its importance in water resource management. Measurements of stream elevation, grade of slope, water temperature, pH, width, depth, turbidity, velocity, and discharge, as well as geomorphological characteristics of catchments such as slope and permeability, were taken at 19 sites …

Impact Of Climate Change On Carbon And Nitrogen Balance In Zostera Marina L. (Eelgrass), Malee Jinuntuya

OES Theses and Dissertations

Seagrasses face vulnerability to both global stressors like Ocean Acidification (OA) and climate warming compounded by local stressors such as eutrophication that reduces light availability, leading to a complex dynamic of positive and negative effect on their growth and survival. Increased dissolved aqueous CO₂ (CO_2(aq)) benefits seagrasses by enhancing photosynthetic and growth rates, but it may increase nutrient demand, potentially depleting nutrient supply, especially in oligotrophic environments.

In this study, the long-term impact of CO₂ on Zostera marina L. (eelgrass) were investigated across a gradient of CO_2(aq) concentrations (55 – 2200 µM CO_{2(aq)) …}

Hydrologic Impact Index For The Pinhoti Hiking Trail, Allie Field

Theses

Author note: The author of this thesis is also published under the name Allie Bobo.

This study aimed to identify flood-prone areas along the Pinhoti Trail and Chinnabee Silent Trail in the Talladega National Forest. Using the Hydrology Flood Index layer that was created using several essential data layers, the research aimed to provide campers, hikers, nature enthusiasts, and trail maintenance teams with information about areas at a higher risk of flash flooding. The Hydrology Flood Index layer rates the risk of flooding on a scale of 1 to 4, with level 1 indicating a low risk of flooding and …

The Role Of Geomorphological Context In Vegetative Succession Within The Breiðamerkurjökull Glacial Foreland, Lucas Nerbonne

Independent Study Project (ISP) Collection

As glaciers retreat worldwide at an accelerating pace, understanding primary succession in these newly exposed landscapes becomes increasingly critical. This study examines the initial vegetative colonization patterns in glacial forelands, focusing on the influence of geomorphological formations of resulting plant communities. By analyzing vegetative communities in glaciofluvial and push moraine deposits, this study highlights how the more varied, channelized morphologies of fluvial deposits create potential microclimates better conducive to heterogenous plant colonization than the homogenous terrain of the nearby push moraine. Vegetative coverage, sediment size, and species abundance was collected at 480 sites across 6 different historical glacial extents across …

The Impacts Of Nature-Based Sediment Restoration Practices On Coastal Wetland Soil Biogeochemistry, Jacob Z. Cheng

LSU Master's Theses

Coastal marshes provide many valuable ecosystem services. However, these wetlands are threatened worldwide, being subject to sea level rise, sediment starvation, subsidence, coastal edge erosion, etc. Many efforts are being made to counteract this wetland loss and preserve the ecosystem services. Two such methods are sediment diversion and the thin layer placement (TLP) of dredged sediment.

Sediment diversion involves reconnecting the main channel of a river body to disconnected wetlands, supplying much needed soil-building materials. However, this method affects the salinity of the waters, introducing large amounts of freshwater into the system. Salinity changes can affect marsh biogeochemistry. Most ecological …

Dissolved Nickel Speciation At The Bermuda Atlantic Time-Series Study (Bats) Site, Caitlyn E. Parente

USF Tampa Graduate Theses and Dissertations

Here I present the first depth profiles of dissolved nickel (DNi) speciation over an annual cycle at the Bermuda Atlantic Time-series Study (BATS) site in the North Atlantic. Seawater samples were collected in March, May, August, and November 2019 and analyzed for labile DNi using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-AdCSV). Labile DNi was measured by CLE-AdCSV as the fraction of DNi that exchanges with an added competitive ligand in an overnight equilibration. Results revealed two distinct fractions of DNi present throughout the water column: a labile fraction, and a strongly organically complexed (i.e., non-labile) fraction. More than 50% …

Evaluating Future Water Availability In Texas Through The Lens Of A Data-Driven Approach Leveraged With Cmip6 General Circulation Models, Wenzhao Li, Dongfeng Li, Hesham El-Askary, Joshua B. Fisher, Zheng N. Fang

Mathematics, Physics, and Computer Science Faculty Articles and Research

Climate change is escalating the frequency and intensity of extreme precipitation events, significantly influencing the spatial and temporal distributions of water resources. This is particularly evident in Texas, a rapidly growing state with a pronounced west-east gradient in water supply. This study utilizes Coupled Model Intercomparison Project Phase 6 (CMIP6) data and data-driven methodology to improve projections of Texas's future water resources, focusing on actual evapotranspiration (AET) and water availability through enhanced Multi-Model Ensembles. The results reveal that the data-driven model significantly outperforms the CMIP5 and CMIP6 models across all skill metrics, underscoring the potential of data-driven methodologies in advancing …

Southern Maine, New Hampshire, And Northern Massachusetts Continental Shelf Geophysical Database: 2022 Field Campaign – Grain Size Data, Station Summaries, And Seafloor Photographs, Larry G. Ward, Rachel C. Morrison, Michael Bogonko

Data Catalog

Presented in this data report are the geophysical data collected during a major field campaign in 2022, with the purpose of obtaining ground truth for the expansion and improvement of high-resolution surficial geology maps of the western Gulf of Maine (WGOM) and for the description of reference sites developed for future evaluations of acoustic systems (Ward et al., 2021a; 2021b). Data from the UNH Ocean Engineering 972 Hydrographic Field Course classes in 2021 and 2022 are also included. This expansion of the geophysical database is being used to verify seafloor classifications in previously mapped areas that lack sufficient data, and …

Application Of Remote Sensing And Spectroradiometry In Geological Mapping: A Case Study Of Handeni (Qds 148) Block, Eastern Mozambique Belt, Tanzania, Masota M. Magigita, Elisante Mshiu, Cassy Mtelela

Tanzania Journal of Science

This study applies remote sensing (RS) as a geologic mapping aid tool , using Handeni Block of Tanzania as a case study. To achieve the objective of this study, we have utilized various RS processing and image enhancement techniques on multispectral data, including ASTER, Landsat 5, Landsat 8, and Sentinel 2A. The method proved successful whereby both Landsat-5-data with band combination (BC) 7:4:2 and 7:5:4 and band ratio (BR) 5/3:5/1:7/5 and Landsat-8 data with BCs 5:6:7 and 7:6:4 mapped out marble units. Sentinel 2A data (with BC 8:11:3, BRs 12/2:11/2:8/11; 12/4:11/3:11/2 and 12/4:12/2:11/3) together with image enhancement decorrelation stretch on …

Clouds In The Ancient Lunar Atmosphere: Water Ice Nucleation On Aerosol Simulants, Mariana C. Aguilar

The Journal of Purdue Undergraduate Research

Today’s moon is vastly different from what it was 3 billion years ago. At that time, it was home to a collisional atmosphere formed through massive amounts of volcanism, releasing enough subsurface gas to sustain surface pressures of up to 1 kPa. Observations of our solar system have taught us that all dense atmospheres are host to clouds and aerosols, and we expect the Moon’s to be no different. Knowing when, where, and under what conditions cloud particles form is important for understanding the evolution of the lunar atmosphere, how it reacted to temperature gradients, and how it cycled volatiles. …

Spatial Analyses On Pre-Earthquake Ionospheric Anomalies And Magnetic Storms Observed By China Seismo-Electromagnetic Satellite In August 2018, Jann-Yeng Tiger Liu, Xuhui Shen, Fu-Yuan Chang, Yuh-Ing Chen, Yang-Yi Sun, Chieh‑Hung Chen, Sergey Pulinets, Katsumi Hattori, Dimitar Ouzounov, Valerio Tramutoli, Michel Parrot, Wei-Sheng Chen, Cheng-Yan Liu, Fei Zhang, Dapeng Liu, Xue-Min Zhang, Rui Yan, Qiao Wang

Mathematics, Physics, and Computer Science Faculty Articles and Research

The China Seismo-Electromagnetic Satellite (CSES), with a sun-synchronous orbit at 507 km altitude, was launched on 2 February 2018 to investigate pre-earthquake ionospheric anomalies (PEIAs) and ionospheric space weather. The CSES probes manifest longitudinal features of four-peak plasma density and three plasma depletions in the equatorial/low-latitudes as well as mid-latitude troughs. CSES plasma and the total electron content (TEC) of the global ionosphere map (GIM) are used to study PEIAs associated with a destructive M7.0 earthquake and its followed M6.5 and M6.3/M6.9 earthquakes in Lombok, Indonesia, on 5, 17, and 19 August 2018, respectively, as well as to examine ionospheric …

Estimation Of Sugarcane Yield Using Multi-Temporal Sentinel 2 Satellite Imagery And Random Forest Regression, Alireza Taravat, Gebeyehu Abebe, Berhan Gessesse, Tsegaye Tadesse

National Drought Mitigation Center: Faculty Publications

Advancements in remote sensing techniques have greatly enhanced crop monitoring and yield estimation, with spectral vegetation indices (VIs) serving as a key component. Our study investigates the use of Sentinel-2 data, notable for its red-edge bands, in estimating sugarcane yield in Ethiopia's Awash Basin. Utilizing 22 VIs from S2 imagery, our approach combines Random Forest (RF) regression with the Recursive Feature Elimination (RFE) algorithm to improve the accuracy of sugarcane yield predictions. The results demonstrate the superior performance of the RF-RFE method over traditional RF with full datasets and Stepwise Multiple Regression (SMR). Particularly, VIs focusing on the red-edge spectral …

Atmospheric And Earth Science 498 Professsional Development, Tess Olten, Robert Griffin

Open Educational Resources (OER)

Whether you're already in the workforce, or you're still in school and haven't yet applied for your first position -- the job application process can be both exciting and demoralizing. Sometimes, finding a new job feels like a full-time job itself -- especially when the competition is steep and the field of candidates is crowded.

How can you help yourself stand out from other applicants and land the job of your dreams? In this course, you'll work through each step of the application process, as well as consider graduate school as an alternative or additional choice. First, you'll explore tips …

Water-Level And Recoverable Water In Storage Changes, High Plains Aquifer, Predevelopment To 2019 And 2017 To 2019, Virginia L. Mcguire, Kellan R. Strauch

United States Geological Survey: Water Reports and Publications

The High Plains aquifer underlies 111.8 million acres (about 175,000 square miles) in parts of eight States: Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines began in parts of the High Plains aquifer soon after the beginning of substantial groundwater irrigation (about 1950). This report presents water-level changes and change in recoverable water in storage in the High Plains aquifer from predevelopment (about 1950) to 2019 and from 2017 to 2019.

Water-level changes from predevelopment to 2019, by well, ranged from a rise of 86 feet to a decline of 265 feet; the range for …

Critical Convergence: Mapping The Boundaries Of How Faculty Interrogate Whiteness In The Geoscience Educational Landscape, James E. Hobbs

Educational Leadership & Policy Studies Dissertations - Archive

This study examined the role of faculty members in interrogating whiteness within geoscience education. The dominant reliance on whiteness as the primary way of knowing in geoscience education has long perpetuated a singular perspective that serves as a mechanism for reinforcing existing power structures rooted in white supremacy. Drawing on tenets from Critical whiteness Studies, Curriculum Theory, and Transformative Learning Theory, this research investigated U.S. higher education faculty members' strategies and challenges in disrupting whiteness within the geoscience curriculum.

Through critical qualitative narrative inquiry, data were collected through semi-structured interviews with geoscience faculty members across multiple institutions across the United …

Re-Evaluating Hydrogen Sulfide As A Sink For Cadmium And Zinc In The Oxic To Suboxic Upper Water Column Of The Pacific Ocean, N. R. Buckley, E. E. Black, J. A. Kenyon, N. T. Lanning, M. Sieber, T. M. Conway, J. N. Fitzsimmons, G. A. Cutter

OES Faculty Publications

Hydrogen sulfide is produced by heterotrophic bacteria in anoxic waters and via carbonyl sulfide hydrolysis and phytoplankton emissions under oxic conditions. Apparent losses of dissolved cadmium (dCd) and zinc (dZn) in oxygen minimum zones (OMZs) of the Atlantic and Pacific Oceans have been attributed to metal-sulfide precipitation formed via dissimilatory sulfate reduction. It has also been argued that such a removal process could be a globally important sink for dCd and dZn. However, our studies from the North Pacific OMZ show that dissolved and particulate sulfide concentrations are insufficient to support the removal of dCd via precipitation. In contrast, apparent …

Integrating Climatological-Hydrodynamic Modeling And Paleohurricane Records To Assess Storm Surge Risk, Amirhosein Begmohammadi, Christine Y. Blackshaw, Ning Lin, Avantika Gori, Elizabeth Wallace, Kerry Emanuel, Jeffrey P. Donnelly

OES Faculty Publications

Sediment cores from blue holes have emerged as a promising tool for extending the record of long-term tropical cyclone (TC) activity. However, interpreting this archive is challenging because storm surge depends on many parameters including TC intensity, track, and size. In this study, we use climatological-hydrodynamic modeling to interpret paleohurricane sediment records between 1851 and 2016 and assess the storm surge risk for Long Island in The Bahamas. As the historical TC data from 1988 to 2016 is too limited to estimate the surge risk for this area, we use historical event attribution in paleorecords paired with synthetic storm modeling …

Global Subterranean Estuaries Modify Groundwater Nutrient Loading To The Ocean, Stephanie J. Wilson, Amy Moody, Tristan Mckenzie, M. Bayani Cardenas, Elco Luijendijk, Audrey H. Sawyer, Alicia Wilson, Holly A. Michael, Bochao Xu, Karen L. Knee, Hyung-Mi Cho, Yishai Weinstein, Adina Paytan, Nils Moosdorf, Chen-Tung Aurthur Chen, Melanie Beck, Cody Lopez, Dorina Murgulet, Guebuem Kim, Mathew A. Charette, Hannelore Waska, J. Severino P. Ibánhez, Gwénaëlle Chaillou, Till Oehler, Shin-Ichi Onodera, Mitsuyo Saito, Valenti Rodellas, Natasha Dimova, Daniel Montiel, Henrietta Dulai, Christina Richardson, Jinzhou Du, Eric Petermann, Xiaogang Chen, Kay L. Davis, Sebastien Lamontagne, Ryo Sugimoto, Guizhi Wang, Hailong Li, Américo I. Torres, Cansu Demir, Emily Bristol, Craig T. Connolly, James W. Mcclelland, Brenno J. Silva, Douglas Tait, Bsk Kumar, R. Viswanadham, Vvss Sarma, Emmanoel Silva-Filho, Alan Shiller, Alanna Lecher, Joseph Tamborski, Henry Bokuniewicz, Carlos Rocha, Anja Reckhardt, Michael Ernst Böttcher, Shan Jiang, Laura M. Hernández-Terrones, Suresh Babu, Beata Szmczycha, Mahmood Sadat-Noori, Felipe Niencheski, Kimberly Null, Craig Tobias, Bongkeun Song, Iris C. Anderson, Isaac R. Santos

OES Faculty Publications

Terrestrial groundwater travels through subterranean estuaries before reaching the sea. Groundwater-derived nutrients drive coastal water quality, primary production, and eutrophication. We determined how dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved organic nitrogen (DON) are transformed within subterranean estuaries and estimated submarine groundwater discharge (SGD) nutrient loads compiling > 10,000 groundwater samples from 216 sites worldwide. Nutrients exhibited complex, nonconservative behavior in subterranean estuaries. Fresh groundwater DIN and DIP are usually produced, and DON is consumed during transport. Median total SGD (saline and fresh) fluxes globally were 5.4, 2.6, and 0.18 Tmol yr⁻¹ for DIN, DON, and DIP, …

An Inconsistent Enso Response To Northern Hemisphere Stadials Over The Last Deglaciation, Ryan H. Glaubke, Matthew W. Schmidt, Jennifer E. Hertzberg, Lenzie G. Ward, Franco Marcantonio, Danielle Schimmenti, Kaustubh Thirumalai

OES Faculty Publications

The dynamics shaping the El Niño-Southern Oscillation's (ENSO) response to present and future climate change remain unclear, partly due to limited paleo-ENSO records spanning past abrupt climate events. Here, we measure Mg/Ca ratios on individual foraminifera to reconstruct east Pacific subsurface temperature variability, a proxy for ENSO variability, across the last 25,000 years, including the millennial-scale events of the last deglaciation. Combining these data with proxy system model output reveals divergent ENSO responses to Northern Hemisphere stadials: enhanced variability during Heinrich Stadial 1 (H1) and reduced variability during the Younger Dryas (YD), relative to the Holocene. H1 ENSO likely intensified …

4500-Year Paleohurricane Record From The Western Gulf Of Mexico, Coastal Central Tx, Usa, Sarah B. Monica, Davin J. Wallace, Elizabeth J. Wallace, Xiaojing Du, Sylvia G. Dee, John B. Anderson

OES Faculty Publications

Texas receives the second-highest number of tropical cyclone (TC) landfalls per year in the United States. At present, long-term TC projections from climate models remain uncertain due to the short and biased nature of Atlantic TC observations. Sediment archives of past storms can help extend the observational record of TC strikes over the past few millennia. When a TC makes landfall along the central Texas coast, coastal downwelling channels and storm currents transport and deposit coarse sediment to a zone of rapid accumulation along the shelf, known as the Texas Mud Blanket (TMB). This “backwash” process results in expansive storm …

Editorial: The Marine Iodine Cycle, Past, Present, And Future, Rosie Chance, Gregory A. Cutter, Dalton S. Hardisty, Anoop S. Mahajan

OES Faculty Publications

In this Research Topic, we bring together ten articles from the diverse research communities interested in the marine iodine cycle, including paleoceanographers, atmospheric chemists, and biogeochemists. The physical chemistry underpinning iodine’s chemical speciation and transformations in the ocean is reviewed by Luther; this paper provides a theoretical basis for the field observations presented in this Research Topic.

A Proxy System Modeling Approach To Combining Tree-Ring And Sediment-Based Paleotempestological Records, Elizabeth J. Wallace, Sylvia Dee, Joshua Bregy, Kerry A. Emanuel

OES Faculty Publications

The short and biased observational record of tropical cyclones (TCs) limits scientific understanding of how these destructive storms respond to climate forcing. Paleohurricane records use natural archives (tree rings, coarse-grained sediment) to reconstruct TC properties (frequency and intensity of rainfall, wind) over the past few hundreds to thousands of years. However, different sensitivities and sampling biases in the various paleohurricane proxies restrict our ability to compile these records into regional or basin-scale TC estimates. Here we test how well pseudo tree-ring records of paleohurricanes capture TC rainfall and occurrence. Using a large set of statistically downscaled storms forced with the …

Submarine Groundwater Discharge At A Mega-Tidal Beach, Raymond D. Craddock, Aaron A. Mohammed, Joseph J. Tamborski, Barret L. Kurylyk

OES Faculty Publications

Tidally influenced groundwater systems in coastal environments represent important mixing zones of fresh groundwater and circulating seawater, manifesting as submarine groundwater discharge (SGD). Water circulation induced by tidal pumping enhances the exchange of chemicals between aquifers and coastal waters and thereby influences the biogeochemistry of coastal zones. Here, we report the results of an SGD field study conducted at a steep, mega-tidal sand and gravel beach along the Canadian coast of the Bay of Fundy, a region with the world's highest tides (semi-diurnal tidal ranges exceeding 10 m). Several physical and geochemical measurement techniques were employed to document the spatiotemporal …

Contrasting Nitrogen Dynamics Across The Mid-Atlantic Bight Shelfbreak Front: Insights From Nitrate Dual Isotopes And Nitrifier Gene Abundance, Yifan Zhu, Margaret R. Mulholland, Corday R. Selden, Dennis J. Mcgillicuddy Jr., Josie Mottram, P. Dreux Chappell, Weifang Gordon Zhang, Julie Granger, Katherine E. Crider, Meredith G. Meyer, Peter W. Bernhardt, Hilde Oliver, Sophie Clayton

OES Faculty Publications

Observations and model studies suggest that front dynamics can enhance phytoplankton productivity. This study tested whether frontal systems also increase the abundance of nitrifying microbes and nitrogen recycling during repeat sampling transects across the Mid‐Atlantic Bight shelfbreak in July 2019. We measured ammonium concentrations, nitrate dual isotopes (δ¹⁵N, δ¹⁸O), and ammonia monooxygenase subunit A (amoA) genes of ammonia‐oxidizing archaea (AOA) and bacteria (AOB). In subsurface shelf waters, ammonium concentrations exceeded 2 μmol L⁻¹, due to a temporary imbalance in regeneration from sinking particles and subsequent nitrification. The inverse correlation between nitrate δ^{15 …}

Marine Emissions Of Methanethiol Increase Aerosol Cooling In The Southern Ocean, Charel Wohl, Julián Villamayor, Martí Galí, Anoop S. Mahajan, Rafael P. Fernández, Carlos A. Cuevas, Adriana Bossolasco, Qinyi Li, Anthony J. Kettle, Tara Williams, Roland Sarda-Esteve, Valérie Gros, Rafel Simó, Alfonso Saiz-Lopez

OES Faculty Publications

Ocean-emitted dimethyl sulfide (DMS) is a major source of climate-cooling aerosols. However, most of the marine biogenic sulfur cycling is not routed to DMS but to methanethiol (MeSH), another volatile whose reactivity has hitherto hampered measurements. Therefore, the global emissions and climate impact of MeSH remain unexplored. We compiled a database of seawater MeSH concentrations, identified their statistical predictors, and produced monthly fields of global marine MeSH emissions adding to DMS emissions. Implemented into a global chemistry-climate model, MeSH emissions increase the sulfate aerosol burden by 30 to 70% over the Southern Ocean and enhance the aerosol cooling effect while …

Heterogeneity Of Nitrogen Fixation In The Mesopelagic Zone Of The South China Sea, Siqi Wu, Xianhui Sean Wan, Moge Du, Xirong Chen, Corday R. Selden, Mar Benavides, Sophie Bonnet, Carolin R. Löscher, M. Robert Hamersley, Margaret R. Mulholland, Xiuli Yan, Shuh-Ji Kao

OES Faculty Publications

Biological dinitrogen (N₂) fixation, the energetically expensive conversion of N₂ gas to ammonia, plays an essential role in balancing the nitrogen budget in the ocean. Accumulating studies show detectable N₂ fixation rates below the euphotic zone in various marine systems, revealing new insights of marine N₂ fixation. However, the reported rates are highly variable and frequently fall close to detection limits, raising the question of the ubiquity and significance of N₂ fixation in the global dark ocean. Using highly sensitive isotopic labeling incubation including a set of control incubations, we confirm the occurrence of mesopelagic N₂ fixation in the South …

Submarine Groundwater Discharge As A Major Nutrient Source In River-Fed Vs. Tidally Dominated Estuaries, Stephanie J. Wilson, Joseph J. Tamborski, Bongkeun Song, Peter Bernhardt, Margaret R. Mulholland

OES Faculty Publications

The tidal tributaries of the lower Chesapeake Bay experience seasonally recurring harmful algal blooms and the significance of submarine groundwater discharge (SGD) as a nutrient vector is largely unknown. Here, we determined seasonal SGD nutrient loads in two tributaries with contrasting hydrodynamic conditions, river-fed (York River) vs. tidally dominated (Lafayette River). Radon surveys were performed in each river to quantify SGD at the embayment-scale during spring and fall 2021. Total SGD was determined from a ²²²Rn mass balance and Monte Carlo simulations. Submarine groundwater discharge rates differed by a factor of two during spring (Lafayette = 11 ± 17 cm …

Supply And Consumption Of Dissolved Organic Phosphorus Across The Subtropical Indian Ocean, Corinne Richard

Honors Theses and Capstones

The Indian Ocean is an understudied region for marine phosphorus (P) biogeochemistry. Emerging evidence indicates marine phytoplankton can adapt to decreasing supplies of inorganic P, a required nutrient for growth, by alternatively utilizing organic forms of P. Here we investigate the dissolved organic phosphorus concentration ([DOP]) distribution across the southern Indian Ocean using observations collected on the I05 US GO-SHIP Cruise (2023) across ~33ºS latitude. We quantify the longitudinal variability of [DOP] in the upper 350 m of the Indian Ocean and infer its rate of biological consumption from surface waters, contributing as an organic nutrient to sustain marine autotrophs …

Improving Accessibility And Understanding: Studying The Impact Of Human Activities And Dam Removals On Anadromous Fish Species In The Pacific Northwest, Adia F. Bennett

Scripps Senior Theses

Human activities in North American watersheds have significantly impacted anadromous fish, causing some species of salmon and steelhead to become threatened and endangered. These fish hold ecological, cultural, and economic importance, yet factors such as habitat destruction, overfishing, pollution, climate change, and hydroelectric dams continue to degrade populations. Dams are particularly harmful to anadromous fish, sparking a recent movement advocating for dam removals. This study uses NOAA’s 2022 Biological Viability Assessment to examine the response of anadromous fish to recent dam removals in the Pacific Northwest. Four populations were selected to analyze due to their interaction with sites that had …