Earth Sciences Commons^™

Model Application Niche Analysis: Assessing The Transferability And Generalizability Of Ecological Models, Jessica B. Moon, Theodore H. Dewitt, Melissa N. Errend, Randall J. F. Bruins, Mary E. Kentula, Sarah J. Chamberlain, M. Siobhan Fennessy, Kusum J. Naithani

United States Environmental Protection Agency: Publications

The use of models by ecologists and environmental managers, to inform environmental management and decision-making, has grown exponentially in the past 50 yr. Due to logistical, economical, and theoretical benefits, model users frequently transfer preexisting models to new sites where data are scarce. Modelers have made significant progress in understanding how to improve model generalizability during model development. However, models are always imperfect representations of systems and are constrained by the contextual frameworks used during their development. Thus, model users need better ways to evaluate the possibility of unintentional misapplication when transferring models to new sites. We propose a method …

Influences Of Hurricanes, Floods, And Organic Production On River-Delta Evolution Over Decadal To Centennial Time-Scales, Crawford M. White

LSU Doctoral Dissertations

Episodic overbank flooding and sediment resuspension events (such as cold front passages or tropical cyclones) are recognized as important natural components for wetlands maintaining vertical equilibrium with sea-level. However, the relative importance of these components to an anthropogenically unmodified delta complex remains unclear. This study uses sediment cores to describe the relative importance of these vertical accretion components the Lafourche and Balize Deltas of the Mississippi River. Existing wetlands of the abandoned lower Lafourche receive no direct fluvial sediment, but instead are supported by sediment resuspended by tropical cyclones and cold fronts that pass over them. Wetlands of the modern …

Effects Of Cultivar And Maternal Environment On Seed Quality In Vicia Sativa, Rong Li, Lijun Chen, Yanpei Wu, Rui Zhang, Carol C. Baskin, Jerry M. Baskin, Xiaowen Hu

Biology Faculty Publications

Production of high quality seeds is of fundamental importance for successful crop production. However, knowledge of the effects of increased temperature resulting from global warming on seed quality of alpine species is limited. We investigated the effect of maternal environment on seed quality of three cultivars of the leguminous forage species Vicia sativa, giving particular attention to temperature. Plants of each cultivar were grown at 1700 and 3000 m a.s.l., and mass, germination, electrical conductivity (EC) of leakage and longevity were determined for mature seeds. Seeds of all three cultivars produced at the low elevation had a significantly lower …

Fruit Weight Is Controlled By Cell Size Regulator Encoding A Novel Protein That Is Expressed In Maturing Tomato Fruits, Qi Mu, Zejun Huang, Manohar Chakrabarti, Eudald Illa-Berenguer, Xiaoxi Liu, Yanping Wang, Alexis Ramos, Esther Van Der Knaap

Plant and Soil Sciences Faculty Publications

Increases in fruit weight of cultivated vegetables and fruits accompanied the domestication of these crops. Here we report on the positional cloning of a quantitative trait locus (QTL) controlling fruit weight in tomato. The derived allele of Cell Size Regulator (CSR-D) increases fruit weight predominantly through enlargement of the pericarp areas. The expanded pericarp tissues result from increased mesocarp cell size and not from increased number of cell layers. The effect of CSR on fruit weight and cell size is found across different genetic backgrounds implying a consistent impact of the locus on the trait. In fruits, CSR …

Nitrogen And Carbon Isotopic Dynamics Of Subarctic Soils And Plants In Southern Yukon Territory And Its Implications For Paleoecological And Paleodietary Studies, Farnoush Tahmesabi, Fred J. Longstaffe, Grant Zazula, Bruce Bennett

Earth Sciences Publications

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C₃ plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ¹⁵N and organic carbon δ¹³C than plants from the same sites with a …

The Uppermost Mantle Seismic Velocity And Viscosity Structure Of Central West Antarctica, J. P. O'Donnell, K. Selway, A. A. Nyblade, R. A. Brazier, D. A. Wiens, S. Anandakrishnan, R. C. Aster, Audrey D. Huerta, T. Wilson, J. Paul Winberry

All Faculty Scholarship for the College of the Sciences

Accurately monitoring and predicting the evolution of the West Antarctic Ice Sheet via secular changes in the Earth's gravity field requires knowledge of the underlying upper mantle viscosity structure. Published seismic models show the West Antarctic lithosphere to be ∼70–100 km thick and underlain by a low velocity zone extending to at least ∼200 km. Mantle viscosity is dependent on factors including temperature, grain size, the hydrogen content of olivine, the presence of partial melt and applied stress. As seismic wave propagation is particularly sensitive to thermal variations, seismic velocity provides a means of gauging mantle temperature. In 2012, a …

Investigating Core Shale Depositional Environments Of Late Pennsylvanian Cyclothems Utilizing Geochemical Proxies To Test The Superestuarine Model, Bryce A. Mathis

LSU Master's Theses

The Late Paleozoic Midcontinent Sea (LPMS) inundated vast areas of the North American interior during glacio-eustatic transgressions, depositing widespread black shales facies within the core shale intervals of major cyclothems. These black shale deposits are unique because no modern analogs can adequately explain the depositional environments and model for organic matter preservation across such vast ancient epicontinental settings. One possible explanation is that a superestuarine circulation system developed across the LPMS during humid interglacial phases, which promoted strong water column stratification and benthic anoxia.

The goal of this research was to test the validity of the superestuarine estuarine model and …

Biofuels From Crop Residue: Soil Organic Carbon And Climate Impacts In The Us And India, Adam Liska

Adam Liska Papers

The transformation of crop residue to soil organic carbon and CO₂ is a conserved process that occurs globally. Due to the mathematics of carbon intensity calculations found in government regulations, the amount of CO₂ emitted from crop residue per unit of energy in biofuel is largely independent of the amount of residue removed and the location of its removal, as shown by results from the US and India.

Soil organic carbon (SOC) levels are at equilibria determined by carbon inputs from plant material (+I_c) and loss from oxidation to CO₂

Are the US results relevant …

Effects Of Regolith Properties On Uv/Vis Spectra And Implications For Lunar Remote Sensing, Ecaterina Ioana Coman

Arts & Sciences Graduate Student Theses and Dissertations

Lunar regolith chemistry, mineralogy, various maturation factors, and grain size dominate the reflectance of the lunar surface at ultraviolet (UV) to visible (VIS) wavelengths. These regolith properties leave unique fingerprints on reflectance spectra in the form of varied spectral shapes, reflectance intensity values, and absorption bands. With the addition of returned lunar soils from the Apollo and Luna missions as ground truth, these spectral fingerprints can be used to derive maps of global lunar chemistry or mineralogy to analyze the range of basalt types on the Moon, their spatial distribution, and source regions for clues to lunar formation history and …

Aluminosilicate Dissolution And Silicate Carbonation During Geologic Co2 Sequestration, Yujia Min

McKelvey School of Engineering Graduate Student Theses & Dissertations

Geologic CO2 sequestration (GCS) is considered a promising method to reduce anthropogenic CO2 emission. Assessing the supercritical CO2 (scCO2)¬–gas or liquid phase water (g, l)–mineral interactions is critical to evaluating the viability of GCS processes. This work contributes to our understanding of geochemical reactions at CO2¬–water (g, l)–mineral interfaces, by investigating the dissolution of aluminosilicates in CO2-acidified water (l). Plagioclase and biotite were chosen as model minerals in reservoir rock and caprock, respectively. To elucidate the effects of brine chemistry, first, the influences of cations in brine including Na, Ca, and K, have been investigated. In addition to the cations, …

Genetic And Biological Studies On Solanum Plants: Insights Into The Leaf Wax Alkane Paleoclimate Proxy, Amanda Lorraine Dorothy Bender

Arts & Sciences Graduate Student Theses and Dissertations

The hydrogen isotopic composition (δ2H) of precipitation records fluxes of water in the hydrological cycle, and can reflect climatic variables such as temperature and humidity. Leaf wax n-alkanes can record δ2H of precipitation; consequently, n-alkanes extracted from sedimentary archives are commonly used as proxies for paleoenvironmental reconstruction. However, the utility of the leaf wax paleoclimate proxy is modulated by uncertainty about how physiological processes affect hydrogen isotopic compositions during alkane biosynthesis. This work aims to improve our understanding of the leaf wax paleoclimate proxy by examining biological and environmental sources of variability on cuticular leaf waxes. We used Solanum (tomato) …

Pergesaran Populiasi Gulma Pada Olah Tanah Dan Pengendalian Gulma Yang Berbeda Pada Tanaman, Uum Umiyati, Denny Kurniadie

Jurnal Kultivasi

Tujuan dari perobaan ini adalah mengetahui pergeseran populasi gulma pada olah tanah dan pengendalian gulma yang berbeda. Percobaan dilakukan dari bulan Juni – Agustus 2016 di UPTD Balai Pengembangan Benih Palawija (BPBP) Desa Barepan Kabupaten Cirebon. Rancangan yang digunakan adalah Rancangan Acak dengan 6 kombinasi perlakuan yang diulang sebanyak 4 kali. Perlakuan tersebut adalah A = Tanpa Olah Tanah dan pengendalian gulma dengan herbisida, B = Tanpa Olah Tanah dan pengendalian gulma secara mekanis, C = Tanpa Olah Tanah dan tanpa pengendalian gulma, D = Olah Tanah Sempurna dan pengendalian gulma dengan herbisida, E = Olah Tanah Sempurna dan pengendalian …

Soputan Volcano, Indonesia: Petrological Systematics Of Volatiles And Magmas And Their Bearing On Explosive Eruptions Of A Basalt Volcano, Syegi Lenarahmi Kunrat

Dissertations and Theses

Soputan volcano is one of the few basaltic volcanoes among 127 active volcanoes in Indonesia. It is part of the Sempu-Soputan volcanic complex located south of Tondano Caldera, North Sulawesi and commonly produces both explosive eruptions with VEI 2-3 and effusive lava dome and flow eruptions. Over the last two decades, Soputan had thirteen eruptions, the most recent in 2016. Most eruptions started explosively, followed by dome growth and in some cases pyroclastic flows. Our study focuses on understanding the magmatic system of Soputan and what processes are responsible for its highly explosive eruptions, which are typically uncommon for a …

Variability In Methane Emissions From West Siberia's Shallow Boreal Lakes On A Regional Scale And Its Environmental Controls, Aleksandr F. Sabrekov, Benjamin R.K. Runkle, Mikhail V. Glagolev, Irina E. Terentieva, Victor M. Stephanenko, Oleg R. Kotsyurbenko, Shamil S. Maksyutov, Oleg S. Pokrovsky

Biological and Agricultural Engineering Faculty Publications and Presentations

Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July–August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m−2 h−1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m−2 h−1 for southern taiga lakes, respectively. …

Do Cosmic Ray Air Showers Initiate Lightning?: A Statistical Analysis Of Cosmic Ray Air Showers And Lightning Mapping Array Data, B. M. Hare, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

It has been argued in the technical literature, and widely reported in the popular press, that cosmic ray air showers (CRASs) can initiate lightning via a mechanism known as relativistic runaway electron avalanche (RREA), where large numbers of high-energy and low-energy electrons can, somehow, cause the local atmosphere in a thundercloud to transition to a conducting state. In response to this claim, other researchers have published simulations showing that the electron density produced by RREA is far too small to be able to affect the conductivity in the cloud sufficiently to initiate lightning. In this paper, we compare 74 days …

Seismic Facies Classification Of An Intraslope Minibasin In The Keathley Canyon, Northern Gulf Of Mexico, Lamine Meroudj

LSU New Orleans Theses and Dissertations

This work examines several volume attributes extracted from 3D seismic data with the goal of seismic facies classification and lithology prediction in intraslope minibasins. The study area is in the Keathley Canyon protraction (KC), within the middle slope of the Northern Gulf of Mexico (GOM). It lays within the tabular salt and minibasins province downdip of the main Pliocene and Pleistocene deltaic depocenters. Interaction between sedimentation and mobile salt substrate lead to the emergence of many stratigraphic patterns in the intraslope minibasins. Interest in subsalt formations left above salt formations poorly logged. Facies classification using Artificial Neural Network (ANN) was …

Respons Tanaman Kedelai (Glycine Max) Varietas Wilis Akibat Pemberian Berbagai Dosis Pupuk N, P, K, Dan Pupuk Guano Pada Tanah Inceptisol Jatinangor, Agus Wahyudin, Fiky Yulianto Wicaksono, Aep Wawan Irwan, Ruminta, Rizka Fitriani

Jurnal Kultivasi

Penelitian ini bertujuan untuk melihat apakah pemberian Pupuk Organik Padat Guano dapat memberikan hasil yang sama dengan pemberian Pupuk N,P,K. Percobaan dilakukan di Rumah Kaca Fakultas Pertanian Universitas Padjadjaran, Jatinangor dengan ketinggian 754m dpl dan menggunakan tanah inceptisol dengan pH 6,18.Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok, terdiri dari 8 perlakuan kombinasi dosis pupuk, yang terdiri dari 100% N,P,K, 100% Pupuk Guano, 75% N,P,K + 100% Pupuk Guano, 50% N,P,K + 100% Pupuk Guano, 75% N,P,K + 75% Pupuk Guano, 50% N,P,K + 75% Pupuk Guano, 75% N,P,K + 50% Pupuk Guano serta 50% N,P,K + 50% Pupuk Guano. …

Single-Grain Optically Stimulated Luminescence Ages Of Brownware Pottery In The Central Rocky Mountains And The Spread Of Numic Ceramic Technology, Judson Byrd Finley, Carlie J. Ideker, Tammy M. Rittenour

Geosciences Faculty Publications

This study presents the results of a single-grain optically stimulated luminescence (SG-OSL) analysis of brownware pottery from four Late Prehistoric-period sites in the Middle Rocky Mountains, Wyoming, USA. SG-OSL of quartz ceramic temper provides improved age control for sites where radiocarbon dating has proven problematic due to old wood, recent wildfires, and calibration uncertainties. SG-OSL results are compared to fine-grain infrared stimulated luminescence (FG-IRSL) results from the same sherds and associated radiocarbon ages. We find that the single-grain technique applied to quartz sand temper provides improved accuracy and precision over both FG-IRSL and radiocarbon. We compare our results to directly …

Respons Pertumbuhan Dan Hasil Benih Kentang G0 Di Dataran Medium Terhadap Waktu Dan Cara Aplikasi Paklobutrazol, Nuzula Suci Azima, Anne Nuraini, Sumadi, Jajang Sauman Hamdani

Jurnal Kultivasi

Aplikasi paklobutrazol pada penanaman kentang di dataran medium dapat mengurangi sintesis giberelin yang menyebabkan penurunan hasil kentang. Efektifitas paklobutrazol tidak hanya dipengaruhi oleh konsentrasi, tetapi juga waktu dan cara aplikasinya. Tujuan penelitian ini adalah untuk memperoleh waktu dan cara aplikasi paklobutrazol yang memberikan pengaruh paling baik dalam meningkatkan hasil benih kentang G0 di dataran medium. Rancangan penelitian menggunakan Rancangan Acak Kelompok (RAK) Faktorial dengan 3 ulangan. Perlakuannya terdiri dari waktu aplikasi paklobutrazol yaitu 28, 35 dan 42 HST (Hari Setelah Tanam) dan cara aplikasi paklobutrazol yaitu disemprot ke daun, disiram ke media tanam dan kombinasi antara penyemprotan ke daun dan …

Reducing Equifinality Using Isotopes In A Process-Based Stream Nitrogen Model Highlights The Flux Of Algal Nitrogen From Agricultural Streams, William I. Ford, James F. Fox, Erik Pollock

Biosystems and Agricultural Engineering Faculty Publications

The fate of bioavailable nitrogen species transported through agricultural landscapes remains highly uncertain given complexities of measuring fluxes impacting the fluvial N cycle. We present and test a new numerical model named Technology for Removable Annual Nitrogen in Streams For Ecosystem Restoration (TRANSFER), which aims to reduce model uncertainty due to erroneous parameterization, i.e., equifinality, in stream nitrogen cycle assessment and quantify the significance of transient and permanent removal pathways. TRANSFER couples nitrogen elemental and stable isotope mass‐balance equations with existing hydrologic, hydraulic, sediment transport, algal biomass, and sediment organic …

A Machine Learning Approach To Estimation Of Downward Solar Radiation From Satellite-Derived Data Products: An Application Over A Semi-Arid Ecosystem In The U.S., Qingtao Zhou, Alejandro Flores, Nancy F. Glenn, Reggie Walters, Bangshuai Han

Geosciences Faculty Publications and Presentations

Shortwave solar radiation is an important component of the surface energy balance and provides the principal source of energy for terrestrial ecosystems. This paper presents a machine learning approach in the form of a random forest (RF) model for estimating daily downward solar radiation flux at the land surface over complex terrain using MODIS (MODerate Resolution Imaging Spectroradiometer) remote sensing data. The model-building technique makes use of a unique network of 16 solar flux measurements in the semi-arid Reynolds Creek Experimental Watershed and Critical Zone Observatory, in southwest Idaho, USA. Based on a composite RF model built on daily observations …

Evaluation Of Simple Geochemical Indicators Of Aeolian Sand Provenance: Late Quaternary Dune Fields Of North America Revisited, Daniel R. Muhs

United States Geological Survey: Staff Publications

Dune fields of Quaternary age occupy large areas of the world's arid and semiarid regions. Despite this, there has been surprisingly little work done on understanding dune sediment provenance, in part because many techniques are time-consuming, prone to operator error, experimental, highly specialized, expensive, or require sophisticated instrumentation. Provenance of dune sand using K/Rb and K/Ba values in K-feldspar in aeolian sands of the arid and semiarid regions of North America is tested here. Results indicate that K/Rb and K/Ba can distinguish different river sands that are sediment sources for dunes and dune fields themselves have distinctive K/Rb and K/Ba …

Improving The Accuracy For The Long-Term Hydrologic Impact Assessment (L-Thia) Model, Anqi Zhang, Lawrence Theller, Bernard A. Engel

The Summer Undergraduate Research Fellowship (SURF) Symposium

Urbanization increases runoff by changing land use types from less impervious to impervious covers. Improving the accuracy of a runoff assessment model, the Long-Term Hydrologic Impact Assessment (L-THIA) Model, can help us to better evaluate the potential uses of Low Impact Development (LID) practices aimed at reducing runoff, as well as to identify appropriate runoff and water quality mitigation methods. Several versions of the model have been built over time, and inconsistencies have been introduced between the models. To improve the accuracy and consistency of the model, the equations and parameters (primarily curve numbers in the case of this model) …

Using P-Band Signals Of Opportunity Radio Waves For Root Zone Soil Moisture Remote Sensing, Phillip H. Lipinski, Benjamin R. Nold, James L. Garrison

The Summer Undergraduate Research Fellowship (SURF) Symposium

Retrieval of Root Zone Soil Moisture (RZSM) is important for understanding the carbon cycle for use in climate change research as well as meteorology, hydrology, and precision agriculture studies. A current method of remote sensing, GNSS-R uses GPS signals to measure soil moisture content and vegetation biomass, but it is limited to 3-5 cm of soil penetration depth. Signals of Opportunity (SoOp) has emerged as an extension of GNSS-R remote sensing using communication signals. P-band communication signals (370 MHz) will be studied as an improved method of remote sensing of RZSM. P-band offers numerous advantages over GNSS-R, including stronger signal …

Mobility Characteristics Of Azithromycin In Soil, Ryan Minter, Jihyun Kim, Linda Lee

The Summer Undergraduate Research Fellowship (SURF) Symposium

The presence of pharmaceutical and personal care products (PPCPs) in the environment has become a widespread problem in recent decades. Azithromycin, a macrolide antibiotic commonly prescribed for infections in humans, has been detected in waste treatment plant discharge and surface waters across the world. Data on the mobility characteristics of azithromycin in soil is scarce, and further studies must be performed to explore the potential for azithromycin leaching to groundwater or becoming available for plant uptake. In this study, azithromycin sorption isotherms were measured on eight soils varying in pH, organic carbon content, and clay content. Soil was equilibrated with …

A Finite Difference Method For Off-Fault Plasticity Throughout The Earthquake Cycle, Brittany A. Erickson, Eric M. Dunham, Arash Khosravifar

Mathematics and Statistics Faculty Publications and Presentations

We have developed an efficient computational framework for simulating multiple earthquake cycles with off-fault plasticity. The method is developed for the classical antiplane problem of a vertical strike-slip fault governed by rate-and-state friction, with inertial effects captured through the radiationdamping approximation. Both rate-independent plasticity and viscoplasticity are considered, where stresses are constrained by a Drucker-Prager yield condition. The off-fault volume is discretized using finite differences and tectonic loading is imposed by displacing the remote side boundaries at a constant rate. Time-stepping combines an adaptive Runge-Kutta method with an incremental solution process which makes use of an elastoplastic tangent stiffness tensor …

Cytonuclear Discordance In The Florida Everglades Invasive Burmese Python (Python Bivittatus) Population Reveals Possible Hybridization With The Indian Python (P. Molurus), Margaret E. Hunter, Nathan A. Johnson, Brian J. Smith, Michelle C. Davis, John S.S. Butterfield, Ray W. Snow, Kristen M. Hart

United States Geological Survey: Staff Publications

The invasive Burmese python (Python bivittatus) has been reproducing in the Florida Everglades since the 1980s. These giant constrictor snakes have caused a precipitous decline in small mammal populations in southern Florida following escapes or releases from the commercial pet trade. To better understand the invasion pathway and genetic composition of the population, two mitochondrial (mtDNA) loci across 1,398 base pairs were sequenced on 426 snakes and 22 microsatellites were assessed on 389 snakes. Concatenated mtDNA sequences produced six haplotypes with an average nucleotide and haplotype diversity of π = 0.002 and h = 0.097, respectively. Samples collected …

Quality Assurance Of Co2 From Natural Gas Source For The Spruce Experiment, Kimberly Arias, Karis J. Mcfarlane, Alexandra Hedgpeth

STAR Program Research Presentations

The goal of the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment project, led by Oak Ridge National Laboratory (ORNL), is to observe and assess ecological responses of peatland ecosystems to increased temperatures and elevated atmospheric CO2 concentrations. Control plots are maintained at ambient temperatures and/or CO2 concentrations. Treatments are applied in a full factorial design; plots are warmed to +2.25, +4.5, +6.75, and +9oC and exposed to an atmospheric CO2 concentration of 800 to 900 ppm. These parameters are set to reflect projected temperatures and atmospheric CO2 levels in the next century. The source for the CO2 that …

Loss Of Buffer Value Due To Aquifer Depletion: The Case Of High Plains Aquifer, Mani Rouhi Rad, Timothy Foster, Nicholas Brozovic

Daugherty Water for Food Global Institute: Faculty Publications

Existing literature in economics and engineering do not realistically capture the effects of aquifer depletion on loss of profits from agricultural production. While the former literature ignores the physical characteristics of aquifer and the relationship between aquifer levels and groundwater availability, the latter strand of literature does not consider farmers' decisionmaking as a result of aquifer depletion. Misspecification of these relationships and their effect on irrigation decisions can result in misunderstanding the consequences of aquifer depletion and may provide ineffective policies. This paper provides a framework to study the effects of aquifer depletion on the profit of agricultural production. We …

Spreading Rate-Dependent Variations In Crystallization Along The Global Mid-Ocean Ridge System, V. Dorsey Wanless, Mark D. Behn

Geosciences Faculty Publications and Presentations

We investigate crustal accretion at mid-ocean ridges by combining crystallization pressures calculated from major element contents in mid-ocean ridge basalt (MORB) glasses and vapor-saturation pressures from melt inclusions and MORB glasses. Specifically, we use established major element barometers and pressures estimated from 192 fractional crystallization trends to calculate crystallization pressures from >9000 MORB glasses across the global range of mid-ocean ridge spreading rates. Additionally, we estimate vapor-saturation pressures from >400 MORB glasses from PETDB and >400 olivine-hosted melt inclusions compiled from five ridges with variable spreading rates. Both major element and vapor-saturation pressures increase and become more variable with decreasing …