Digital Commons Network^™

Effects Of Tidal Flooding On Estuarine Biogeochemistry: Quantifying Flood-Driven Nitrogen Inputs In An Urban, Lower Chesapeake Bay Sub-Tributary, Alfonso Macías-Tapia, Margaret R. Mulholland, Corday R. Selden, J. Derek Loftis, Peter W. Bernhardt

OES Faculty Publications

Sea level rise has increased the frequency of tidal flooding even without accompanying precipitation in many coastal areas worldwide. As the tide rises, inundates the landscape, and then recedes, it can transport organic and inorganic matter between terrestrial systems and adjacent aquatic environments. However, the chemical and biological effects of tidal flooding on urban estuarine systems remain poorly constrained. Here, we provide the first extensive quantification of floodwater nutrient concentrations during a tidal flooding event and estimate the nitrogen (N) loading to the Lafayette River, an urban tidal sub-tributary of the lower Chesapeake Bay (USA). To enable the scale of …

A Kernel-Based Change Detection Method To Map Shifts In Phytoplankton Communities Measured By Flow Cytometry, Corinne Jones, Sophie Clayton, François Ribalet, E. Virginia Armbrust, Zaid Harchaoui

OES Faculty Publications

1. Automated, ship-board flow cytometers provide high-resolution maps of phytoplankton composition over large swaths of the world's oceans. They therefore pave the way for understanding how environmental conditions shape community structure. Identification of community changes along a cruise transect commonly segments the data into distinct regions. However, existing segmentation methods are generally not applicable to flow cytometry data, as these data are recorded as ‘point cloud’ data, with hundreds or thousands of particles measured during each time interval. Moreover, nonparametric segmentation methods that do not rely on prior knowledge of the number of species are desirable to map community shifts. …

Diatom Hotspots Driven By Western Boundary Current Instability, Hilde Oliver, Weifeng G. Zhang, Walker O. Smith Jr., Philip Alatalo, P. Dreux Chappell, Andrew J. Hirzel, Corday R. Selden, Heidi M. Sosik, Rachel H.R. Stanley, Yifan Zhu, Dennis J. Mcgillicuddy Jr.

OES Faculty Publications

Abstract Climatic changes have decreased the stability of the Gulf Stream (GS), increasing the frequency at which its meanders interact with the Mid-Atlantic Bight (MAB) continental shelf and slope region. These intrusions are thought to suppress biological productivity by transporting low-nutrient water to the otherwise productive shelf edge region. Here we present evidence of widespread, anomalously intense subsurface diatom hotspots in the MAB slope sea that likely resulted from a GS intrusion in July 2019. The hotspots (at ∼50 m) were associated with water mass properties characteristic of GS water (∼100 m); it is probable that the hotspots resulted from …

Plate Boundary And Triple Junction Control Of Shatsky Rise Formation And Implications For Other Ocean Plateaus, Jennifer E. Georgen, Katrina Shotorban

OES Faculty Publications

In the study of marine large igneous provinces, investigations often focus on the importance of mantle plumes in generating excess magmatism. Few studies, however, have addressed the role of plate boundary processes in promoting widespread and extensive mantle melting. This study investigates how spreading center geometry may have facilitated the emplacement of Shatsky Rise, an oceanic plateau in the western Pacific Ocean. The largest structure within Shatsky Rise, Tamu Massif, was created ∼140–150 Ma at the Pacific-Izanagi-Farallon (PIF) ridge-ridge-ridge triple junction. Moreover, the PIF triple junction was one of three triple junctions operating in close proximity at the time, as …

Lagrangian Betweenness As A Measure Of Bottlenecks In Dynamical Systems With Oceanographic Examples, Enrico Ser-Giacomi, Alberto Baudena, Vincent Rossi, Mick Follows, Sophie Clayton, Ruggero Vasile, Cristóbal López, Emilio Hernández-García

OES Faculty Publications

The study of connectivity patterns in networks has brought novel insights across diverse fields ranging from neurosciences to epidemic spreading or climate. In this context, betweenness centrality has demonstrated to be a very effective measure to identify nodes that act as focus of congestion, or bottlenecks, in the network. However, there is not a way to define betweenness outside the network framework. By analytically linking dynamical systems and network theory, we provide a trajectory-based formulation of betweenness, called Lagrangian betweenness, as a function of Lyapunov exponents. This extends the concept of betweenness beyond the context of network theory relating hyperbolic …

Synoptic Mesoscale To Basin Scale Variability In Biological Productivity And Chlorophyll In The Kuroshio Extension Region, Sophie Clayton, Hilary I. Palevsky, Luanne Thompson, Paul D. Quay

OES Faculty Publications

The Kuroshio current separates from the Japanese coast to become the eastward flowing Kuroshio Extension (KE) characterized by a strong latitudinal density front, high levels of mesoscale (eddy) energy, and high chlorophyll a (Chl). While satellite measurements of Chl show evidence of the impact of mesoscale eddies on the standing stock of phytoplankton, there have been very limited synoptic, spatially resolved in situ estimates of productivity in this region. Here, we present underway measurements of oxygen/argon supersaturation (ΔO2/Ar), a tracer of net biological productivity, for the KE made in spring, summer, and early autumn. We find large seasonal differences in …

Impact Of Ocean Carbonation On Long-Term Regulation Of Light Harvesting In Eelgrass Zostera Marina, Billur Celebi-Ergin, Richard C. Zimmerman, Victoria J. Hill

OES Faculty Publications

Seagrasses account for approximately 10% of the total carbon stored in the ocean, although photosynthesis of seagrasses is carbon-limited at present oceanic pH levels. Therefore, increasing atmospheric CO₂ concentration, which results in ocean acidification/carbonation, is predicted to have a positive impact on seagrass productivity. Previous studies have confirmed the positive influence of increasing CO₂ on photosynthesis and survival of the temperate eelgrass Zostera marina, but the acclimation of photoprotective mechanisms in this context has not been characterized. We aimed to quantify the long-term impacts of ocean acidification on photochemical control mechanisms that promote photosynthesis while simultaneously protecting …

Marine Phytoplankton Functional Types Exhibit Diverse Responses To Thermal Change, S. I. Anderson, A. D. Barton, Sophie Clayton, S. Dutkiewicz, T. A. Rynearson

OES Faculty Publications

Marine phytoplankton generate half of global primary production, making them essential to ecosystem functioning and biogeochemical cycling. Though phytoplankton are phylogenetically diverse, studies rarely designate unique thermal traits to different taxa, resulting in coarse representations of phytoplankton thermal responses. Here we assessed phytoplankton functional responses to temperature using empirically derived thermal growth rates from four principal contributors to marine productivity: diatoms, dinoflagellates, cyanobacteria, and coccolithophores. Using modeled sea surface temperatures for 1950-1970 and 2080-2100, we explored potential alterations to each group's growth rates and geographical distribution under a future climate change scenario. Contrary to the commonly applied Eppley formulation, our …

Detrital Neodymium And (Radio)Carbon As Complementary Sedimentary Bedfellows? The Western Arctic Ocean As A Testbed, Melissa S. Schwab, Jörg D. Rickli, Robie W. Macdonald, H. Rodger Harvey, Negar Haghipour, Timothy I. Eglinton

OES Faculty Publications

Interactions between organic and detrital mineral phases strongly influence both the dispersal and accumulation of terrestrial organic carbon (OC) in continental margin sediments. Yet the complex interplay among biological, chemical, and physical processes limits our understanding of how organo-mineral interactions evolve during sediment transfer and burial. In particular, diverse OC sources and complex hydrodynamic processes hinder the assessment of how the partnership of organic matter and its mineral host evolves during supply and dispersal over continental margins. In this study, we integrate new and compiled sedimentological (grain size, surface area), organic (%OC, OC-δ¹³C, OC-F¹⁴C), and inorganic …

Neodymium Isotope Geochemistry Of A Subterranean Estuary, Darren A. Chevis, T. Jade Mohajerin, Ningfang Yang, Jaye E. Cable, E. Troy Rasbury, Sidney R. Hemming, David J. Burdige, Jonathan B. Martin, Christopher D. White, Karen H. Johannesson

OES Faculty Publications

Rare earth elements (REE) and Nd isotope compositions of surface and groundwaters from the Indian River Lagoon in Florida were measured to investigate the influence of submarine groundwater discharge (SGD) on these parameters in coastal waters. The Nd flux of the terrestrial component of SGD is around 0.7 ± 0.03 μmol Nd/day per m of shoreline across the nearshore seepage face of the subterranean estuary. This translates to a terrestrial SGD Nd flux of 4 ± 0.2 mmol/day for the entire 5,880 m long shoreline of the studied portion of the lagoon. The Nd flux from bioirrigation across the nearshore …

A Recirculating Eddy Promotes Subsurface Particle Retention In An Antarctic Biological Hotspot, Katherine L. Hudson, Matthew John Oliver, Josh Kohut, Michael S. Dinniman, J. M. Klinck, Carlos Moffat, Hank Statscewich, Kim S. Bernard, William Fraser

OES Faculty Publications

Palmer Deep Canyon is one of the biological hotspots associated with deep bathymetric features along the Western Antarctic Peninsula. The upwelling of nutrient-rich Upper Circumpolar Deep Water to the surface mixed layer in the submarine canyon has been hypothesized to drive increased phytoplankton biomass productivity, attracting krill, penguins and other top predators to the region. However, observations in Palmer Deep Canyon lack a clear in-situ upwelling signal, lack a physiological response by phytoplankton to Upper Circumpolar Deep Water in laboratory experiments, and surface residence times that are too short for phytoplankton populations to reasonably respond to any locally upwelled nutrients. …

Bioactive Trace Metals And Their Isotopes As Paleoproductivity Proxies: An Assessment Using Geotraces-Era Data, T. J. Horner, S. H. Little, T. W. Conway, J. R. Farmer, Jennifer E. Hertzberg, D. J. Janssen, A.J.M. Lough, J.L. Mckay, A. Tessin, S.J.G. Galer, S. L. Jaccard, F. Lacan, A. Paytan, K. Wuttig, Geotraces-Pages Biological Productivity Working Group Members

OES Faculty Publications

Phytoplankton productivity and export sequester climatically significant quantities of atmospheric carbon dioxide as particulate organic carbon through a suite of processes termed the biological pump. Constraining how the biological pump operated in the past is important for understanding past atmospheric carbon dioxide concentrations and Earth's climate history. However, reconstructing the history of the biological pump requires proxies. Due to their intimate association with biological processes, several bioactive trace metals and their isotopes are potential proxies for past phytoplankton productivity, including iron, zinc, copper, cadmium, molybdenum, barium, nickel, chromium, and silver. Here, we review the oceanic distributions, driving processes, and depositional …

Generation Of Excited Species In A Streamer Discharge, Shirshak K. Dhali

Electrical & Computer Engineering Faculty Publications

At or near atmospheric pressure, most transient discharges, particularly in molecular gases or gas mixture containing molecular gases, result in a space charge dominated transport called a streamer discharge. The excited species generation in such discharges forms the basis for plasma chemistry in most technological applications. In this paper, we simulate the propagation of streamers in atmospheric pressure N₂ to understand the energy partitioning in the formation of various excited species and compare the results to a uniform Townsend discharge. The model is fully two-dimensional with azimuthal symmetry. The results show a significantly larger fraction of the energy goes …

Taxonomic And Nutrient Controls On Phytoplankton Iron Quotas In The Ocean, Benjamin S. Twining, Olga Antipova, P. Dreux Chappell, Natalie R. Cohen, Jeremy E. Jacquot, Elizabeth L. Mann, Adrian Marchetti, Daniel C. Ohnemus, Sara Rauschenberg, Alessandro Tagliabue

OES Faculty Publications

Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of …

Constraining 20th‐Century Sea‐Level Rise In The South Atlantic Ocean, Thomas Frederikse, Surendra Adhikari, Tim J. Daley, Sönke Dangendorf, Roland Gehrels, Felix Landerer, Marta Marcos, Thomas L. Newton, Graham Rush, Aimée B.A. Slangen, Guy Wöppelmann

OES Faculty Publications

Sea level in the South Atlantic Ocean has only been measured at a small number of tide-gauge locations, which causes considerable uncertainty in 20th-century sea-level trend estimates in this basin. To obtain a better-constrained sea-level trend in the South Atlantic Ocean, this study aims to answer two questions. The first question is: can we combine new observations, vertical land motion estimates, and information on spatial sampling biases to obtain a likely range of 20th-century sea-level rise in the South Atlantic? We combine existing observations with recovered observations from Dakar and a high-resolution sea-level reconstruction based on salt-marsh sediments from the …

Microbially Induced Sedimentary Structures In Clastic Deposits: Implication For The Prospection For Fossil Life On Mars, Nora Noffke

OES Faculty Publications

Abundant and well-preserved fossil microbenthos occurs in siliciclastic deposits of all Earth ages, from the early Archean to today. Studies in modern settings show how microbenthos responds to sediment dynamics by baffling and trapping, binding, biostabilization, and growth. Results of this microbial-sediment interaction are microbially induced sedimentary structures (MISS). Successful prospection for rich MISS occurrences in the terrestrial lithological record requires unraveling genesis and taphonomy of MISS, both of which are defined only by a narrow range of specific conditions. These conditions have to coincide with high detectability which is a function of outcrop quality, bedding character, and rock type. …

An Assessment Of Regional Icesat-2 Sea-Level Trends, Brett Buzzanga, Eduard Heijkoop, Benjamin D. Hamlington, R. Steven Nerem, Alex Gardner

OES Faculty Publications

Sea-level rise is an important indicator of ongoing climate change and well observed by satellite altimetry. However, observations from conventional altimetry degrade at the coast where regional sea-level changes can deviate from the open-ocean and impact local communities. With the 2018 launch of the laser altimeter onboard ICESat-2, new high-resolution observations of ice, land, and ocean elevations are available. Here we assess the potential benefits of sea level measured by ICESat-2 by comparing to data from Jason-3 and tide gauges. We find good agreement in the linear rates computed from the independent observations, with an absolute average residual of 3.60 …

Lipid Markers And Compound-Specific Carbon Isotopes As Diet And Biosynthesis Reflectors In The Northern Neptune Whelk Neptunea Heros, H. Rodger Harvey, Rachel Mcmahon, Karen A. Taylor

OES Faculty Publications

A suite of lipid biomarkers plus compound-specific carbon isotopes of major sterols were determined in muscle tissues across increasing sizes of northern Neptune whelks Neptunea heros, developing eggs and potential diets to link trophic patterns, metabolism and carbon sources on the Chukchi Sea shelf. Analysis of primary prey included the northern clam Astarte borealis, water column particulate organic matter (POM) and surface sediments near the collection sites. Sterols specific to major algal groups along with algal-derived polyunsaturated fatty acids (C20:5n-3, C20:4n-3, C22:6n-3) in whelk muscle tissue reflected the importance of algal primary production to benthic consumers and its …

Radium Isotopes As Submarine Groundwater Discharge (Sgd) Tracers: Review And Recommendations, J. Garcia-Orellana, V. Rodellas, Joseph Tamborski, M. Diego-Feliu, P. Van Beek, Y. Weinstein, M. Charette, A. Alorda-Kleinglass, H.A. Michael, T. Stieglitz, J. Scholten

OES Faculty Publications

Submarine groundwater discharge (SGD) is now recognized as an important process of the hydrological cycle worldwide and plays a major role as a conveyor of dissolved compounds to the ocean. Naturally occurring radium isotopes (Ra-223, Ra-224, Ra-226 and Ra-228) are widely employed geochemical tracers in marine environments. Whilst Ra isotopes were initially predominantly applied to study open ocean processes and fluxes across the continental margins, their most common application in the marine environment has undoubtedly become the identification and quantification of SGD. This review focuses on the application of Ra isotopes as tracers of SGD and associated inputs of water …

Innovation Capacity: A Firm Level Response To Subsidy Activity In A National Setting, Assyad Al-Wreiket, Royce D. Burnett, Christopher J. Skousen, Ouadie Akaaboune

Accounting Faculty Publications

The purpose of this paper is to investigate the effect subsidies have on firm-level innovation across Eastern European and Central Asian countries and to assess if these effects move to increase firm-level capability. Specifically, we investigate the extent subsidy programs act to shape and guide firm-level innovative capabilities and how the presence of such capabilities affect operational performance. We employ a Probit model to investigate firm-level innovation and OLS regression to assess how subsidies, in association with the decision to adopt foreign technology and in-house research and development (R&D) affect firm productive capacity. Results suggest subsidies promote innovation and that …

Solutions For Fermi Questions, November 2021: Question 1: Chess Moves, Question 2: Cat Litter, Larry Weinstein

Physics Faculty Publications

Answers to the questions: How many chess moves are made by Americans each year? How much cat litter did Americans scoop last year?

Solutions For Fermi Questions, September 2021: Question 1: Cell Phone Gold, Question 2: Food For Thought, Larry Weinstein

Physics Faculty Publications

Answers to the questions: "How much gold is in a cell phone? Is it worth mining cell phones for gold?"

Question 1: Chess Moves; Question 2: Cat Litter, Larry Weinstein

Physics Faculty Publications

How many chess moves are made by Americans each year?

How much cat litter did Americans scoop last year?

Solutions For Femi Questions, October 2021: Rising Water Level: Popping Many Pimples, Larry Weinstein

Physics Faculty Publications

[Introduction] How much would sea levels rise if everyone jumped in the ocean? (Thanks to Bob Friedhoffer for suggesting the problem.)

To estimate this, we need to know the number of people, the average volume of a person, and the area of the oceans. This is the kind of estimation problem where the inputs are relatively well known, and we are calculating the answer to see its order of magnitude.

There are about 7 X 10⁹ people in the world. If each person has a mass of 100 kg (in round numbers), then they each have a volume …

Fabrication, Treatment And Cryogenic Testing Of Single-Cell Cavities Made Of Forged Ingot Nb, B. Khanal, G. Ciovati, P. Dhakal, F. Marhauser, R. Rimmer, G. R. Myneni

Physics Faculty Publications

Forged ingot Nb is a novel processing method to obtain Nb discs used for the fabrication of superconducting radio-frequency cavities. We have fabricated two single 1.5 GHz single cell cavities made from forged Nb ingot with residual resistivity ratio of ~ 100 . The cavity were electropolished ~ 120 μm, followed by 650 °C/10hrs degassing in UHV furnace. Additional ~ 25 mm electropolishing was done before the rf test. The first cavity reached ~14 MV/m.

Thermal Conductivity Of Electroplated Copper Onto Bulk Niobium At Cryogenic Temperatures, G. Ciovati, P. Dhakal, I. Parajuli, M. R. P. Pathiranage, T. Saeki

Physics Faculty Publications

Superconducting radio-frequency (SRF) cavities made of high-purity bulk niobium are widely used in modern particle accelerators. The development of metallic outer coatings with high thermal conductivity would have a beneficial impact in terms of improved thermal stability, reduced material cost and for the development of conduction-cooled, cryogenic-free SRF cavities. Several high-purity, fine-grain Nb samples have been coated with 2’4 mm thick copper by electroplating. Measurements of the thermal conductivity of the bimetallic Nb/Cu samples in the range 2’7 K showed values of the order of 1 kW/(m K) at 4.3 K. Very good adhesion between copper and niobium was achieved …

Renormalization And Mixing Of Staple-Shaped Wilson Line Operators On The Lattice Revisited, Yao Ji, Jian-Hui Zhang, Shuai Zhao, Ruilin Zhu

Physics Faculty Publications

Transverse-momentum-dependent parton distribution functions and wave functions (TMDPDFs/TMDWFs) can be extracted from lattice calculations of appropriate Euclidean matrix elements of staple-shaped Wilson line operators. We investigate the mixing pattern of such operators under lattice renormalization using symmetry considerations. We perform an analysis for operators with all Dirac structures, which reveals mixings that are not present in one-loop lattice perturbation theory calculations. We also present the relevant one-loop matching in a renormalization scheme that does not introduce extra nonperturbative effects at large distances, both for the TMDPDFs and for the TMDWFs. Our results have the potential to greatly facilitate numerical calculations …

Effect Of A Mean Free Path On Nonlinear Losses Of Trapped Vortices Driven By A Rf Field, Manula Randhika Pathirana Walive Pathiranage, Alex Gurevich

Physics Faculty Publications

We report extensive numerical simulations on nonlinear dynamics of a trapped elastic vortex under rf field, and its dependence on electron mean free path li. Our calculations of the field-dependent residual surface resistance Ri(H) take into account the vortex line tension, the linear Bardeen-Stephen viscous drag and random distributions of pinning centers. We showed that Ri(H) decreases significantly at small fields as the material gets dirtier while showing field independent behavior at higher fields for clean and dirty limit. At low frequencies Ri(H) increases smoothly with the field amplitude at small H and levels off at higher fields. The mean …

Improving The Operational Lifetime Of The Cebaf Photo-Gun By Anode Biasing, J. T. Yoskowitz, G. A. Krafft, G. Palacios-Serrano, S. Wijethunga, J. Grames, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, M. Stutzman, R. Suleiman, S. B. Van Der Geer

Physics Faculty Publications

The operating lifetime of GaAs-based photocathodes in DC high voltage electron photo-guns is dominated by the ionization rate of residual beamline gas molecules. In this work, experiments were performed to quantify the improvement in photocathode charge lifetime by biasing the photo-gun anode with a positive voltage, which repels ions generated downstream of the anode. The photo-cathode charge lifetime improved by almost a factor of two when the anode was biased compared to the usual grounded configuration. Simulations were performed using the particle tracking code General Particle Tracer (GPT) with a new custom element. The simulation results showed that both the …

Semi-Inclusive Deep Inelastic Scattering Measurements Of A = 3 Nuclei With Clas12 In Hall B, S. Li, R. Cruz Torres, J. Rittenhouse West, F. Yuan, A. Denniston, O. Hen, J. Kahlbow, T. Kutz, J. R. Pybus, E. P. Segarra, C. Ayerbe-Gayoso, H. Bhatt, D. Bhetuwal, T. Chetry, B. Devkota, J. Dunne, D. Dutta, L. El Fassi, T. Gaballah, A. Karki, M. Amarian, C. Fogler, F. Hauenstein, C. Hyde, G. Gavalian, L. B. Weinstein, D. Gaskell, D. W. Higinbotham, C. Keith, C. Keppel, J. Maxwell, A. Tadepalli, D. Meekins, D. Nguyen, S. Stepanyan, H. Szumila-Vance, Z. G. Xiao, Y. Wang, Z. H. Ye, Y. P. Zhang, K. Griffioen, P. Bosted, A. Bianconi, G. Costantini, M. Leali, S. Migliorati, L. Venturelli, V. Mascagna, A Boyer, F. Benmokhtar, A. Gadsby, A. Parker, L. Baashen, B. Raue, W. J. Briscoe, S. Ratliff, A. Schmidt, E. Seroka, P. Sharp, P. G. Solazzo, I. I. Strakovsky, K. Adhikari, G. Niculescu, K.-T. Brinkmann, S. Diehl, A. Kripko, Sheren Alsalmi, Tyler J. Hague, A. Beck, S. Beck, E. Cohen, I. Korover, G. Johansson, C. Neuburger, E. Piasetzky, Michael Nycz, R. Capobianco, T. Haywars, F.-X. Girod, K. Joo, A. Kim, V. Klimenko, R. Santos, U. Shrestha, P. Simmerling, J. Richard, N. Trotta, B. Mckinnon, W. Brooks

Physics Faculty Publications

We propose to measure precision ratios of charged pion electroproduction in Semi-Inclusive Deep Inelastic Scattering from ²D, ³He and ³H targets to test the flavor dependence of the EMC effect in the valence quark region. This trio of targets has been chosen to minimize hadron attenuation effects while maximizing nuclear asymmetry. The standard configuration CLAS12 detector will be used in the experiment to detect scattered electrons and knocked-out pions. A new, dedicated, tritium target that will be developed for the approved quasi-elastic experiment, E12-20-005 [1], will be used. The experiment will measure semi-inclusive production of charged pions over a wide …