Earth Sciences Commons^™

10be Dating Of Last Glacial Maximum Moraines And Subsequent Glacial Retreat In Chirripó National Park, Costa Rica, Caleb Emeka Okpala

Dartmouth College Master’s Theses

During the Last Glacial Maximum (LGM; ~26-19 ka) and Termination 1 (~19-12 ka), the expansion and retreat of glaciers across the Southern and Northern Hemispheres, as well as other paleoclimate proxies, document a complex pattern of global climate change. While the timing and magnitude of LGM cooling and subsequent warming is relatively well constrained in mid- and high-latitude regions across both hemispheres, less information is available about climate changes in the tropics. To provide more information about tropical climate conditions during the LGM and Termination 1, I mapped and dated the extents of past glaciers in two valleys in Chirripó …

Dust-Driven Mechanism For Marine Particle Aggregation: Interactions Between Clay Minerals, Heterotrophic Bacteria And Organic Matter Influences Aggregation In Marine Systems, Vignesh Gokuladas Menon

Dartmouth College Master’s Theses

Atmospheric dust deposition plays a crucial role in marine biogeochemical cycles, yet mechanisms underlying its impact on particle dynamics remain unclear. This study investigates the synergistic interactions between marine heterotrophic bacteria and clay minerals in seawater, focusing on their effect on Transparent Exopolymer Particles (TEP) production and organoclay aggregation. Field experiments in the Gulf of Maine and laboratory roller tank studies were conducted using natural microbial communities and model heterotrophic bacterial strains (Alteromonas sp. EZ55, Marinobacter adhaerens HP15, and Sulfitobacter sp. NAS-14.1). Results demonstrate that clay exposure significantly enhances TEP production by bloom-associated heterotrophic bacteria, with increases up to …

A General Framework For Modeling Subregional Path Effects, T. E. Buckreis, P. Wang, S. J. Brandenberg, J. P. Stewart

Civil & Environmental Engineering Faculty Publications

Next Generation Attenuation (NGA) West2 ground motion models (GMMs) include regional path adjustments for broad jurisdictional regions, which necessarily averages spatially variable path effects within those regions. We extend that framework to account for systematic variations in attenuation within subregions defined in consideration of geologic differences. In recent years, cell-based methods which systematically account for spatial variations by summing the attenuation effects over a fine discretization of uniform-rectangular cells (e.g., Dawood and Rodriquez-Marek 2013; Kuehn et al. 2019) have been shown to be an effective alternative to regionalization and a step towards modelling non-ergodic path effects. The main drawbacks of …

Revised Geologic Map And Structural Interpretation Of The Mineral King Pendant, Southern Sierra Nevada, California (Usa): Evidence For Kilometer-Scale Folding And Structural Imbrication Of A Permian To Mid-Cretaceous Volcanosedimentary Assemblage, David C. Greene, Jade Star Lackey, Erik W. Klemetti

Faculty Publications

No abstract provided.

Basal Topography And Carbon Accumulation Rate Of A Rare Northern California Coastal Fen, Sarah Leidinger

Cal Poly Humboldt theses and projects

Increasingly, the importance of peatlands as biodiversity hotpots, year-round water storage features, and significant carbon sinks are being recognized. Despite this, they are one of the most vulnerable ecosystems globally. While some peatland conservation and restoration initiatives are being developed, a greater understanding of small peatlands is needed to make management decisions. This study aims to determine the timing of peat formation, peat volume, and carbon accumulation rates of the Conspicuous Scoop Fen, a small (2.1-acre) fen near Bridgeville, California (~840 m.a.s.l.). During the summers of 2022 and 2023, I collected 39 m of peat cores at 14 sampling locations. …

Delayed Coastal Inundations Caused By Ocean Dynamics Post-Hurricane Matthew, Kyungmin Park, Emanuele Di Lorenzo, Yinglong J. Zhang, Tal Ezer, Fei Yi

CCPO Publications

Post Hurricane Abnormal Water Level (PHAWL) poses a persistent inundation threat to coastal communities, yet unresolved knowledge gaps exist regarding its spatiotemporal impacts and causal mechanisms. Using a high-resolution coastal model with a set of observations, we find that the PHAWLs are up to 50 cm higher than the normal water levels for several weeks and cause delayed inundations around residential areas of the U.S. Southeast Coast (USSC). Numerical experiments reveal that while atmospheric forcing modulates the coastal PHAWLs, ocean dynamics primarily driven by the Gulf Stream control the mean component and duration of the shelf-scale PHAWLs. Because of the …

Evidence That Ericoid Mycorrhizal Shrubs Can Outcompete Ectomycorrhizal Trees For Nitrogen In Tannin-Rich Litter, Kai C. Rains, Caroline Bledsoe, Tamara E. Kraus, Nina Wurzburger

School of Geosciences Faculty and Staff Publications

Mycorrhizal associations of trees play a key role in ecosystem biogeochemistry, yet we know relatively little about the nutrient acquisition strategies of ericoid mycorrhizal (ErM) shrubs, despite their prevalence in forest understories. ErM shrubs tend to produce litter with high concentrations of polyphenols, which form decay-resistant complexes with organic nitrogen (N). Some ErM fungi appear capable of producing a diverse suite of extracellular enzymes, but it is unclear whether this enables ErM shrubs to acquire the N from their own litter, and whether this ability is greater than that of ectomycorrhizal (EcM) trees, with which they commonly co-occur. Here, we …

Uav-Based Wetland Monitoring: Multispectral And Lidar Fusion With Random Forest Classification, Robert Van Alphen, Kai C. Rains, Mel Rodgers, Rocco Malservisi, Timothy H. Dixon

School of Geosciences Faculty and Staff Publications

As sea levels rise and temperatures increase, vegetation communities in tropical and sub-tropical coastal areas will be stressed; some will migrate northward and inland. The transition from coastal marshes and scrub–shrubs to woody mangroves is a fundamental change to coastal community structure and species composition. However, this transition will likely be episodic, complicating monitoring efforts, as mangrove advances are countered by dieback from increasingly impactful storms. Coastal habitat monitoring has traditionally been conducted through satellite and ground-based surveys. Here we investigate the use of UAV-LiDAR (unoccupied aerial vehicle–light detection and ranging) and multispectral photogrammetry to study a Florida coastal wetland. …

Optimizing Field-Linked Simulations Of Dry Season Uptake And Monsoon Infiltration Within An Aspen-Mixed Conifer Forest, Raymond J. Hess

Master's Theses

Climate models forecast that headwater catchments in the western U.S. will undergo a reduction in snowpack, early season snowmelt, and increases in evapotranspiration. The resulting extended dry season will stress vegetation in mountainous watersheds throughout the Upper Colorado River Basin. We investigate infiltration patterns and root water uptake in response to dry season disturbances within the East River watershed in Colorado. To do this, we collected soil cores, measured matric potential and sap flow, and monitored tree xylem and soil for stable isotopes of water (2H, 18O) in two soil profiles to 90 cm depth (with three Engelmann spruce and …

Plasmid-Borne Biosynthetic Gene Clusters Within A Permanently Stratified Marine Water Column, Paraskevi Mara, David Geller-Mcgrath, Elizabeth A. Suter, Gordon T. Taylor, Maria G. Pachiadaki, Virginia P. Edgcomb

BCES: Faculty Publications

Plasmids are mobile genetic elements known to carry secondary metabolic genes that affect the fitness and survival of microbes in the environment. Well-studied cases of plasmidencoded secondary metabolic genes in marine habitats include toxin/antitoxin and antibiotic biosynthesis/resistance genes. Here, we examine metagenome-assembled genomes (MAGs) from the permanently-stratified water column of the Cariaco Basin for integrated plasmids that encode biosynthetic gene clusters of secondary metabolites (smBGCs). We identify 16 plasmid-borne smBGCs in MAGs associated primarily with Planctomycetota and Pseudomonadota that encode terpenesynthesizing genes, and genes for production of ribosomal and non-ribosomal peptides. These identified genes encode for secondary metabolites that are …

Descriptive Statistical Analysis Of Experimental Data For Wettability Alteration With Smart Water Flooding In Carbonate Reservoirs, Muhammad Ali Buriro, Mingzhen Wei, Baojun Bai, Ya Yao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Smart water flooding is a promising eco-friendly method for enhancing oil recovery in carbonate reservoirs. the optimal salinity and ionic composition of the injected water play a critical role in the success of this method. This study advances the field by employing machine learning and data analytics to streamline the determination of these critical parameters, which are traditionally reliant on time-intensive laboratory work. the primary objectives are to utilize data analytics to examine how smart water flooding influences wettability modification, identify key parameter ranges that notably alter the contact angle, and formulate guidelines and screening criteria for successful lab design. …

Examining Downshear Reformation In Tropical Cyclones, Nathalie Rivera Torres

Electronic Theses & Dissertations (2024 - present)

The development of a new low-level circulation center in tropical cyclones, known as downshear reformation, can lead to sudden changes in storm structure and intensity, representing a challenge in forecasting tropical cyclones. This phenomenon is commonly observed in weak tropical cyclones (e.g., tropical depressions, tropical storms) experiencing moderate to strong vertical wind shear (> 5 m s-1), when the vertical wind shear organizes convection in the downshear region of the tropical cyclone, and lower-tropospheric vorticity is generated within the intense convection. Downshear reformation has been proposed as a mechanism for intensification, sometimes rapidly, in tropical cyclones under unfavorable environmental wind …

Enhancing A Computer Model To Evaluate Rainwater Harvesting And Reuse Strategies For Landscape Irrigation Under Current And Future Climate Conditions, Siyu Li

Electronic Theses & Dissertations (2024 - present)

Urbanization and climate change have detrimental impacts on water quantity and quality. Rainwater harvesting/reuse for landscape irrigation with rain barrels/cisterns, which can assist urban hydrological/water quality restoration and provide a beneficial resource for irrigating landscape, holds significant potentials in urban areas under current and future climates. However, the impacts of rainwater harvesting/reuse strategies for landscape irrigation under a changing climate need to be comprehensively evaluated to assist decision-making. In addition, a comprehensive tool is needed to help stakeholders develop efficient strategies to harvest rainwater for landscape irrigation with rain barrels/cisterns.

To address the needs, the simulation of the sub-daily hydrological …

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 …

Uqsees-1, Scott Brande

All 3D Rock Models

Model UQSEES-1 - granite - igneous rock

SketchFab link: https://sketchfab.com/3d-models/uqsees-1-cb8d8e00ce0340f4b6ffd3b95e0d890d

129, Scott Brande

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Model 129 - granite - igneous rock

SketchFab link: https://sketchfab.com/3d-models/129-01de2e735f8e482c99f1a95417b7ad33

152, Scott Brande

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Model 152 - pumice - igneous rock

SketchFab link: https://sketchfab.com/3d-models/152-47906f0c520349d99e885d362eba0947

142, Scott Brande

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Model 142 - obsidian - igneous rock

SketchFab link: https://sketchfab.com/3d-models/142-9541b71ef7b34399a3f822938f599c73

200, Scott Brande

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Model 200 - amphibolite - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/200-de19175088954efc83da6de6d085ec9a

185, Scott Brande

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Model 185 - oolite - sedimentary rock

SketchFab link: https://sketchfab.com/3d-models/185-86c0cdff6970452691d5c8c05d87ea9d

242, Scott Brande

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Model 242 - schist - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/242-e203c2aa90414627a6107474cbda4385

151, Scott Brande

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Model 151 - pegmatite - igneous rock

SketchFab link: https://sketchfab.com/3d-models/151-fd641f4eb24e47cb900a1b783b9967cb

186, Scott Brande

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Model 186 - oolite - sedimentary rock

SketchFab link: https://sketchfab.com/3d-models/186-4ccc3d44148f45d682d63e00cd9ca1d7

214, Scott Brande

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Model 214 - quartzite - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/214-fe71e05bff274beb94af62035e47ced2

247, Scott Brande

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Model 247 - schist - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/247-aea85a461ca2414489bd0b04a4df3bdcN

260, Scott Brande

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Model 260 - breccia - sedimentary rock

SketchFab link: https://sketchfab.com/3d-models/260-6711f31b529448739ead7cf0a33b94ee

271, Scott Brande

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Model 271 - marble - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/271-370135d0aba44ec38c87c827123db334

190, Scott Brande

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Model 190 - sandstone - sedimentary rock

SketchFab link: https://sketchfab.com/3d-models/190-29d202409b1246a1b550db9c6f41b25c

265, Scott Brande

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Model 265 - gneiss - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/265-9ea30b81d35c49d1bb066367002d1fac

220, Scott Brande

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Model 220 - slate - metamorphic rock

SketchFab link: https://sketchfab.com/3d-models/220-39857764278746049e60bd9238ed3891