Symposium Program

9:05am - 9:20am

Title: Incremental Learning for Passive Microwave Precipitation Retrievals using Advanced Technology Microwave Sounder

Authors: Mahyar Garshasbi, Buddha Subedi, and Ardeshir Ebtehaj

Keywords: Precipitation Retrieval, ATMS, Machine Learning.

Abstract: Spaceborne passive microwave (PMW) radiometry has been instrumental in global precipitation monitoring; however, retrieval uncertainties remain high, particularly for cross-track sounders, due to variable footprints and channel configurations that are primarily optimized for moisture and temperature profiling rather than precipitation. Existing operational products often suffer from angular biases, limited swath utilization, unrealistic rainfall probability distributions, and misclassification of precipitation phase. These limitations are further compounded by the lack of globally accurate and representative precipitation labels, as commonly used products from the Dual-frequency Precipitation Imaging Radar (DPR) and CloudSat Profiling Radar (CPR) are sparse, lack global coverage, and exhibit heterogeneous error structures across precipitation regimes. To address these challenges, this study presents a supervised retrieval algorithm that incrementally trains an ensemble of extreme gradient-boosted decision trees by augmenting base learners with pre-training on reanalysis data and posttraining on coincident DPR and CPR observations matched to the Advanced Technology Microwave Sounder (ATMS). By transferring prior information from reanalysis to posterior constraints from radar observations and adopting a sequential detection–estimation strategy for precipitation phase and rate retrieval, the proposed approach yields retrievals across the full ATMS swath that are largely free from persistent deficiencies in current Global Precipitation Measurement (GPM) operational products. In particular, the method resolves bimodal artifacts in rainfall retrievals and mitigates systematic high-latitude snowfall biases, including overestimation across the Arctic and underestimation across the Antarctic. Validation against independent Multi-Radar Multi-Sensor (MRMS) data further demonstrates improved performance in precipitation phase detection and rate estimation relative to both reanalysis and individual spaceborne radar observations.

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9:20am - 9:35am

Title: Reading Between the Wavelengths: Decoding Indirect Indicators of Toxic Blooms Using Hyperspectral Satellite Observations

Authors: K Denesh, Lucas Clarke Burnette, Lief Olmanson, Miki Hondzo, Ardeshir Ebtehaj

Keywords: Remote Sensing, Hyperspectral, NASA PACE, Microcystin, Lake Erie, Water Quality

Abstract: Cyanotoxins, such as microcystin, pose a major public health hazard during freshwater cyanobacterial blooms. However, the detection of these toxic blooms is challenging because the toxins themselves lack direct optical absorption features. We demonstrate that hyperspectral observations from NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) Ocean Color Instrument (OCI) can indirectly detect elevated microcystin concentrations by identifying subtle signatures hidden within the gaps of traditional multispectral satellite sensors to exploit bloom-related optical signatures. Using two years of NOAA in situ microcystin measurements from the Western Lake Erie Basin, we performed bootstrapped Welch’s t-tests to identify OCI wavelengths sensitive to high-microcystin conditions. These bands and derived spectral-shape metrics are then used to train a nested cross-validated random forest classifier, achieving 89.5% accuracy despite limited training data. The results reproduce expected spatial and seasonal patterns of toxic blooms and highlight the dominant role of spectral-shape metrics in the pigment absorption and red-edge regions. These findings suggest that hyperspectral data may provide a nuanced pathway for monitoring toxic bloom occurrence in inland freshwater systems.

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9:35am - 9:50am

Title: Structural Similarity Assessment of Precipitation and Temperature in NEX-GDDP-CMIP6 Simulations over the Contiguous United States

Authors: Sandesh Dahal, Ardeshir Ebtehaj, Miki Hondzo, Azharuddin Mohammed, and Vipin Kumar

Keywords: Climate models, precipitation, near-surface air temperature, structural similarity index measure (SSIM), Wasserstein distance, hydrologic applications

Abstract: In a warming climate, spatiotemporal changes in precipitation and temperature can impact hydrologic processes and thus the quality of freshwater ecosystems. This study evaluates the performance of 35 downscaled and bias-corrected CMIP6 General Circulation Models (GCMs) from NASA’s Earth Exchange Global Daily Downscaled Projections (NEX-GDDP, 0.25° resolution) by comparing their historical simulations (1950–2014) of precipitation and near-surface air temperature with those from ERA5 reanalysis across the Contiguous United States. Two complementary metrics are employed: the Wasserstein Distance (WD) to assess distributional similarity and the Structural Similarity Index Measure (SSIM) to quantify spatial consistency on a monthly scale. The results reveal systematic uncertainties: The NEX-GDDP-CMIP6 simulations struggle to reproduce the warm-season spatial organization and temporal trends of precipitation in regions predominantly influenced by mesoscale convective systems. Additionally, they exhibit the lowest SSIM scores for cold-season temperatures, highlighting challenges in simulating snow–albedo feedback mechanisms, cloud radiative processes, and boundary-layer dynamics. The models are ranked based on the similarity of their historical simulations for both precipitation and temperature. In summary, IPSL-CM6A-LR leads in monthly distributional proximity while MIROC-ES2L leads in monthly spatial similarity for total precipitation and mean temperature. Regionally, MIROC-ES2L performs best in the Midwest, Northern Great Plains, Northwest, and Southern Plains, whereas NorESM2-LM, FGOALS-g3, and GFDL-CM4-gr2 lead in the Northeast, Southeast, and Southwest, respectively. Spatial similarity analysis of maps of temporal trends reveals that BCC-CSM2-MR is the top model across CONUS.

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9:50am - 10:05am

Title: Jumping Worms, moving soils: Exploring invasive earthworms' impacts on soil erosion in the Great Lakes Region 

Authors: Nate Lund, Lee Frelich, Angela Gupta, Erin Buchholz, Kyungsoo Yoo

Keywords: Erosion, earthworms, invasive species, soil

Abstract: Ecology and erosion are tightly coupled. Ecosystems play a critical role in forming, protecting, and aggregating soils, and although the ecology of the natural world is complex, and it is well known that humans too have left a substantial mark--with impacts that have, in turn, produced sweeping consequences for erosion. Research on these consequences has largely focused on agricultural systems, where both the magnitude and the visibility of erosion are greatest. Yet throughout the twentieth and twenty‑first centuries, humans have also driven dramatic changes in ostensibly undisturbed landscapes, particularly forests, through another pathway: earthworm invasion. Earthworms alter nearly every level of an ecosystem, from understory vegetation to soil morphology, and their widespread establishment raises an important question: if earthworms so profoundly reshape ecosystems, and ecosystems so strongly regulate erosion, how does earthworm invasion influence erosion? In this study, we sought to answer three fundamental questions about the future of earthworm‑invaded forests: (Q1) What is the topography of the forests that earthworms are invading? (Q2) What is the erosion rate in earthworm‑infested forests? (Q3) What is the predominant process of earthworm‑induced erosion—advection or diffusion? We address Q1 using publicly available data on topography, land use, soils, and erosion and Q2 and Q3 through an erosion‑pin study. We find that forests in the Great Lakes region occupy steeper‑than‑average terrain, forests infested with European and jumping worms exhibit substantial variability in erosion rates, and that, even theoretically, there is strong reason to expect earthworm‑driven erosion, as earthworms influence with many of the environmental factors that both drive and resist soil movement.

10:05am - 10:20am

Title: Expanding Upon the Early Eocene Geochronological Record of the Wind River Basin, WY, USA Using Paleosol-Based Magnetostratigraphy

Authors: Jarred Asselta, Emily J. Beverly, Andrew Flynn, Josh Feinberg, David Fox, James Blount 

Keywords: Hyperthermals, Paleoenvironment, Paleoclimate, Rock Magnetics 

Abstract: The Early Eocene was a time of globally warm climate highlighted by hyperthermal events which drove fluctuations in fluvial systems in response to elevated CO2 levels. The Wind River Formation (WRF) in the Wind River Basin of central Wyoming is characterized by fluvial sandstones and conglomerates interbedded with floodplain paleosols and mudstones. The construction of a magnetostratigraphic record and the identification of geomagnetic reversals and a deeper evaluation of the recorded mammalian biostratigraphy will provide additional age constraints for the WRF. We can constrain the bottom of the section using chemostratigraphy to identify the Paleocene Eocene Thermal Maximum (PETM), which coincides with the possible North American Land Mammal Age (NALMA) of the latest Clarkforkian, Cf3, or earliest Wasatchian,Wa0. The top of the measured section is constrained by a detrital zircon maximum depositional age of 50.87 Ma ± 0.46 or latest Wasatchian, Wa7. Combined with the magnetostratigraphy (geomagnetic polarity chrons 24r through 23r), this chronology will allow us to understand the response of terrestrial environments to hyperthermals like the PETM, Eocene Thermal Maximum 2, and the Early Eocene Climate Optimum. Here, data will be presented on magnetostratigraphy and biostratigraphy for a site in the Dubois Badlands Wilderness Study Area outside of Dubois, WY.

Lithostratigraphic sections measured at the Dubois site capture ~150 m of fluvial and floodplain sandstones and mudstones. Floodplain paleosols were described based on pedogenic features (e.g., color, grain size, texture, horizonation, etc.). Oriented samples of floodplain paleosols were used for construction of a magnetostratigraphic record through a combination of alternating field and thermal demagnetization protocols. Although these samples contain goethite, magnetite, and pigmentary hematite, our results show that detrital hematite is the carrier of remanence at the time of deposition. Paleomagnetic analyses cover the first ~50 m of measured section based on paleomagnetic samples that were collected every ~3 m or bracketed thick, coarse sandstones. Preliminary results are consistent with reversed polarity throughout. Ongoing paleomagnetic work will refine the chronology of the section to chron 23n.1n or 22r. The improved chronology of the WRF will allow for high resolution paleoenvironmental reconstructions using bulk geochemistry proxies for paleoprecipitation and pedogenic carbonates for clumped isotope thermometry. These proxies tied into the chronology will help determine the impact of hyperthermal events.

Title: The Relationship Between Mica Content and Finite Strain Within Central Australian Quartzites

Authors: Finn Nicholson

Keywords: Mica, Quartzite, Finite Strain, Deformation, Central Australia, Metaconglomerate

Abstract: To best understand the deformation of Earth’s crust, one must take quartz into consideration, as it is the dominant mineral of the mid to upper continental crust. From mountain-building to rifting events, quartz plays a central role in crustal rheology. Quartz may be a key component of Earth’s uppermost layer, but it is not without some mineral baggage. Within natural quartzites, mica is often observed as well. This platy, sheet-like mineral inclusion holds the power to weaken quartz as it undergoes deformation. The primary aim of this research is to utilize a natural suite of deformed quartzite pebbles, sampled from a metaconglomerate unit within the White Range of Central Australia, to determine the relationship between mica content and finite strain. By comparing mica content to strain magnitude derived from pebble shapes, this study aims to determine whether higher mica content correlates with greater finite strain, providing insight into how compositional variations amongst quartz-dominated rocks influence deformation style.

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Title: Novel Release Mechanism of Microplastics and Nanoplastics by Environmentally Relevant Sand Abrasion

Authors: Sarah Ziemann, Claire Hartwig Alberg, Himani Yadav, Ji Qin, Syeed Md Iskander, Ehsanur Rahman, Ezra Kone, Jiaqi Li, Jiarong Hong, and Boya Xiong

Keywords: mechanical degradation of polymer, nanoplastic release, sand abrasion, abrasive and adhesive wear, silica layer, input power

Abstract: Mechanical degradation of plastics is a major source of micro- and nanoplastics (MPs/

NPs) released into natural environments. However, our understanding of this process remains limited, and methods to quantify the mechanical degradation intensity are lacking. We designed a quantitative device to study MP/NP release arising strictly from surface abrasion of low-density polyethylene (LDPE) films by freely sliding/rolling dry sand over 7 months. We characterized the dynamic changes in released products, polymer surface, and sand surface, and correlated the release rates with input power from sliding friction. Environmentally relevant sand surface abrasion alone released only NPs (<400 nm, suspended) and water-extracted dissolved organic carbon (2−44 μg PE/cm2). Beyond suspended debris, we discovered that MPs/NPs’ (sub- to low-micron) can transfer onto sand grains- a novel and major release mechanism that could serve as a new source of MPs/NPs. Simultaneously, a dynamic layer of sand minerals was deposited on LDPE. Such mutual transfer is hypothesized to be stochastic and to interfere with the subsequent MP/NP release. Our findings highlight that MP/NP release and fate from environmentally relevant sand abrasion are more complex than our previous understanding. Correlating the input power with harmonized degradation rates indicated that solid abrasion releases debris more efficiently than fluid shear.

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Title: Thirty Years of Low-Key Hydrology: Flow Conditions Between Storms in Three Minnesota Watersheds

Authors: Ashlyn Cowgill, Diana Karwan

Keywords: hydrology, baseflow, streams, tile drainage

Abstract: Baseflow sustains perennial streamflow between storm events and is traditionally assumed to originate from groundwater.  Multiple methods exist to estimate or parameterize baseflow, each with assumptions and tradeoffs. Digital filters, one established method, define baseflow as gradually changing discharge controlled by groundwater. Tile drainage can also sustain flow between events without exhibiting groundwater recession behavior. As a result, filters often classify inter-event tile drainage as baseflow, even though its source and dynamics differ from those of groundwater, thereby violating the assumption that all low-frequency flow is groundwater-derived. In Southern Minnesota, land use has remained relatively stable over the past several decades, but tile drainage has expanded, potentially altering annual and seasonal baseflow dynamics. To evaluate how baseflow conditions have changed over the past thirty years, we will analyze discharge from two agricultural and one forested HUC-8 watershed using two hydrograph-separation approaches: the Eckhardt filter, which smooths hydrographs to estimate sustained baseflow, and the event-based automated workflow of Millar et al. (2022), which isolates storm events and quantifies event-scale responses. After identifying when and how these systems are changing, we will relate hydrologic metrics to potential drivers. Assumed tile-drainage extent, derived from 30-m rasters based on farmer reporting and soil map data, along with climatic variables, will be compared to annual and seasonal changes in baseflow index, total flow, stormflow, and baseflow. While this analysis does not directly isolate tile-drainage contributions to sustained flow, statistical relationships between tile-drain network extent and changing baseflow metrics will help clarify subsurface hydrology in these data-limited systems and support more effective watershed management decisions.

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Title: Mitigating Aeolian and Runoff-Driven Nutrient Transport in Sugar Beet Production Systems

Authors: Mehmet Ozturk, Anna Cates, Lindsay Pease, Nicholas Webb

Keywords: Wind Erosion, Cover Crop, Nutrient Transportation, Runoff

Abstract: The Red River Valley of Minnesota is renowned for its fertile black soils, which are conducive to the cultivation of sugar beets. It is crucial to protect these carbon-rich soils from erosion, yet the cultivation of sugarbeet as a root crop necessitates the intensive and frequent utilization of heavy machinery. Sugar beet harvest has been demonstrated to be a significant cause of soil degradation, leaving minimal residue on the soil surface. This has resulted in a heightened vulnerability to erosion, including water and wind. 

The present study was conducted with the objective of evaluating the effects of cover crops (CC) on surface runoff, sediment transportation, and the nutrient content of sediment and runoff waters. To this end, a station experiment was conducted by using summer-seeded mustard and rye, as well as fall-drilled rye. Additionally, the effects of cover crops on sediment mass transportation collected by using Big Spring Number Eight (BSNE) dust samplers and the nutrient content of soil sediments were examined in a field experiment. This field experiment included fall-planted rye and a control treatment on a larger scale. 

Climate conditions between the years (Year1: record high snowfall and Year2: record high minimum temperatures) played a critical role in this research. Field trials indicated that well-established winter rye effectively mitigated horizontal mass flux; notably, over 80% of sediment flux occurred in plots without cover crops, underscoring the importance of CC in protecting Minnesota’s valuable black soils. The dust transportation was extremely high in the second year. There was no statistical difference in surface runoff between CC treatments while partial dependence graph of Random Forest model demonstrated that runoff was slightly higher in control treatments.

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Title: Distribution of soil organic carbon after Euro-American agriculture influenced geomorphic change in the Whitewater valley (Winona County, Minnesota)

Authors: Mei Abraham, Andrew Wickert, Nic Jelinski

Keywords: Geomorphology, soil science, soil and carbon dynamics, agriculture, loss on ignition

Abstract: Soil organic carbon (SOC) strongly influences soil properties such as soil structure and overall soil health as well as its ability to support plant growth. As Euro-Americans brought their agricultural practices into the Whitewater valley (present day Winona County, Minnesota) they initiated an era of rapid changes to the landscape. These transformations make the Whitewater valley a unique field site to study SOC and its presence in the floodplain over an extensive period of time, providing insight into the historical influence Euro-American agriculture has had on the landscape. 

Prior to Euro-American agriculture, the Whitewater valley’s upland ridges and floodplain were covered in native grasslands and forests. Records of significant geomorphic change in the Upper Mississippi River Valley became noticeable by the early 19th century primarily attributed to the construction of croplands (Knox, 2001). Geomorphic change affected by agriculture can be generalized based on other patterns seen throughout the Midwest, through similar patterns of removal of natural vegetation, accelerated erosion, sedimentation, and flooding events that have created alluvial fans and floodplains (Wood, 2023).

In 1939, Stafford Coleman Happ established 94 transects to study sedimentation. Since being established, multiple survey studies were replicated, creating an extensive record of sediment erosion. To study SOC, sediment samples were collected in Fall 2025 (at several depths) along several of Happ’s survey lines (see Wood, 2023), in order to have a calendar age of the sediments for data analysis. The soil samples were analyzed using the loss on ignition method (LOI) which measures the amount of organic matter (organic carbon) found in the samples by determining the difference in mass before and after ignition. Through this analysis a stratigraphic column will be constructed to interpret how organic carbon is distributed in the White Water Valley as a direct influence of historic Euro-American agriculture practices.

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Title: Magnetic properties of Antarctic subglacial precipitates

Authors: Ellie McBride & Josh Feinberg

Keywords: subglacial precipitates, magnetic characteristics, glacier-bedrock chemical processes, Antarctic lithics

Abstract: Much of Antarctica has been covered by glaciers for at least the last 30 million years, making it difficult to recover geologic records from the south pole between ~1 Ma to the early Oligocene. However, chemical processes occurring at wet glacier-bedrock contacts allow for the progressive nucleation and growth of silicate and carbonate mineral precipitates. Fragments of these subglacial precipitates can be plucked during glacial movement and delivered to the surface by upward flow within glacial ice. Previous studies of these precipitates show laminations and sedimentary features that indicate orientation at formation, and isotopic studies of carbonate precipitates reveal ages as old as 6.6 Ma.  Here we present the first-ever survey of the magnetic properties of eleven Antarctic subglacial precipitates. Our goal is to determine whether these materials may record information about the Earth’s magnetic field at the time of their formation as well as about the oxygen conditions at the glacier-bedrock contact. We provide imagery of these precipitates and report the samples’ low field magnetic susceptibilities, alternating field demagnetization, saturation magnetization, coercivity, and magnetic mineral identification.

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Title: Core-lating Paleosol Characteristics and Paleoenvironment Conditions in Baringo Basin, Kenya

Authors: Madison Rafter, Emily J. Beverly, William Lukens, Kathryn Snell, John Kingston, and Carly McCarthy

Keywords: Paleosol, paleoclimate, mineralogy

Abstract: Early hominins relied on lake margin paleoenvironments in the Eastern African Rift for food, water, and habitat. The Eastern African Monsoon (EAM) provides ~70% of the region’s annual precipitation. A multi-proxy approach for paleosol characteristics is important to develop a better understanding of the paleoclimatic setting of paleo-Lake Baringo during an important time in hominin evolution and for modeling anthropogenic climate change in this vulnerable region. A sediment core (HSPDP-BTB-13, 3.29-2.56 Ma) was drilled in Baringo Basin, Kenya, through Pliocene-Pleistocene paleolake strata and includes the mid-Pliocene Warming Period (mPWP; 3.25-2.95 Ma) and the onset of global cooling leading to Northern Hemisphere Glaciation (NHG; ~2.75 Ma). Paleosols (n = 78) represent 57% of the HSPDP-BTB-13 core which consists of lacustrine, fluvial, paleosol, alluvial, and tephra units. Paleosol B-horizons and parent material samples (n = 98) were used to examine changes over time in paleosol maturity and bulk mineralogy by using X-Ray Diffraction (XRD). Paleosols were classified as paleo-Entisols, Inceptisols, or Vertisols, while their maturity was quantified using soil characteristics such as horizonation, bioturbation, and degree of carbonate development. The paleosols consist of mainly feldspathic minerals, clay minerals, quartz, zeolites, and carbonate. Older paleosols in the mPWP contain more quartz and less feldspar, with more abundant feldspars in the younger paleosols as the NHG began. This is interpreted as increased weathering because quartz is more resistant than feldspars, which weather to clay minerals with increased monsoonal precipitation. Scanning data collected from the HSPDP-BTB-13 core can also be used to interpret environmental and climatic changes. These datasets include color, magnetic susceptibility, elemental abundances and ratios that can be used as proxies for conditions including pedogenic input (Ca/Fe), reducing conditions (Fe/Mn), physical vs chemical weathering (K/Al), and authigenic carbonate precipitation (Sr/Ca). Changes in these datasets broadly line up with the changes in mineralogy and changes in stable isotope abundances (δ13C, δ18O, Δ47). Future work will focus on identifying clay minerals and using principal component analysis to understand the drivers of change in the Baringo Basin sediments.

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Title: Early Eocene Paleoprecipitation Reconstructions using Paleosol Bulk Geochemistry from the Wind River Basin, WY, USA

Authors: Brynn Miller, Emily Beverly, Jarred Asselta, and James Blount

Keywords: Climate change, paleoclimate, paleoenvironment, hyperthermals, rainfall

Abstract: The Early Eocene Climatic Optimum (EECO; ~53 to 49 Ma) was characterized by sustained high temperatures and atmospheric CO2 levels that led to more intense rainfall events and shifting climate systems across North America. Paleoclimate records of EECO conditions serve as an analog to modern climate change and can assist in understanding Earth’s response to anthropogenic warming. Paleoclimate information from the EECO in the Wind River Basin of central Wyoming is captured in paleosols (fossil soils) throughout the Wind River Formation. These paleosols were identified and described using standard USDA soil characterization techniques (e.g. Munsell soil color, horizonation) from two field sites: Byrd Draw Wash (BDW) near Dubois, WY and Hell’s Half Acre (HHA) west of Casper, WY. We described ~125 m of stratigraphy at BDW and ~90 m of stratigraphy at HHA. At BDW, paleosols (n = 38) are primarily carbonate-rich paleo-Aridisols separated by fluvially-deposited thick sandstones and conglomerates. At HHA, sandstones are thinner and finer grained with paleosols (n = 30) containing few pedogenic carbonate nodules. We analyzed bulk geochemistry samples using X-ray fluorescence to reconstruct mean annual precipitation (MAP) using three proxies: CIA-K, RF-MAP, and PPM1.0. The most appropriate proxy for paleo-Aridisols, RF-MAP2.0, revealed that MAP at BDW ranged from 338 to 695 with a mean of 412 mm yr-1 (SD = 102). HHA was nearly twice as wet with MAP ranging from 675 to 806 with a mean of 747 mm yr-1 (SD = 35). The field sites received higher MAP during the EECO than in the present day where MAP for BDW and HHA are around 252 mm yr-1 and 310 mm yr-1, respectively. Future work will refine MAP chronology and compare trends in the Wind River Basin to other Eocene basins across North America, allowing for further understanding of the terrestrial response to rapid warming.

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Title: Eocene Paleoclimate Reconstruction Using Stable Isotopes of Pedogenic Carbonates From the Wind River Basin, Wyoming, USA

Authors: Sirena B. Rygiel, Emily J. Beverly, Jarred T. Asselta, James Blount, Andrew G. Flynn

Keywords: Hyperthermals, Paleosols, PETM

Abstract: Sedimentary basins across Western North America record hyperthermal trends in carbon and oxygen isotopes, which are crucial to studying how the Earth will respond to higher atmospheric CO2 and how humans will need to adapt to this warming. We prepared and analyzed 46 Eocene pedogenic carbonate samples from two sites in the Wind River Basin, Wyoming: 7 from Hell’s Half Acre and 39 from Byrd Draw Wash. During 2023-2025 field seasons, paleo-aridisol pedogenic carbonates were collected in stratigraphic succession to identify hyperthermal trends through time. 0.5-1.0g was drilled from carbonate nodules within the samples for stable isotope (𝛿13Cpc and 𝛿18Opc) analysis by the Center for Stable Isotopes at the University of New Mexico using isotope ratio mass spectrometry. 𝛿13Cpc in preexisting stable isotope data from the San Juan, Bighorn, and Wind River Basins range from -15 to -9.4‰, -14.6 to -6.9‰, and -9.5 to -4.6‰, respectively. 𝛿18Opc ranges from -11.7 to -5.4‰, -9.2 to -7.7‰, and -9.8 to -8.5‰, respectively. Mean 𝛿13Cpc is similar in the San Juan (mean = -10.9‰; SD=1.1) and Bighorn Basins (mean = -10.6‰; SD=2.7), but lower in the Wind River Basin (mean = -7.5‰; SD=1.1). Further 𝛿13Cpc and 𝛿18Opc and geochronological record data of the Wind River Basin will be analyzed and compared to those of similar basins to expand knowledge of past landscape response to rapid increases in CO2 and to predict future climate change. 

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Title: Exploring the phylogeny of Equini (Perissodactyla) through Combined-Evidence Approaches

Authors: Hayley K. Orłowski

Keywords: Phylogenetics, Equidae, Total-evidence

Abstract: Fossil horses (Equids) are icons of evolution; since 1870, they have served a central role in the development of modern evolutionary theory as well as in broader efforts to disseminate knowledge of evolutionary biology among the populace. Despite this, the interrelationships of the clade Equini and of Equus, the sole extant genus of equid, remain poorly understood. Recent advances in ancient DNA have provided clarity to some long-standing debates in fossil horse taxonomy, but have also uprooted much of our understanding of horse relationships as revealed by morphological data. Consequently, a number of recent phylogenetic analyses of equids based on morphology are incompatible with analyses based upon molecular data. In order to bridge this gap and investigate the interrelationships of the

Equini, I constructed a dataset of 71 morphological characters of 42 fossil and extant equin taxa from the published literature and from collections visits, as well as published mitochondrial genomes from all equin species for which sequence data are known. The resulting data were analyzed with both molecular scaffold approaches and Bayesian total- evidence approaches in order to examine the relationships among Equini. Resulting trees are well-resolved and show broad agreement across approaches. Analyses uniformly show strong support for the monophyly of Equus sensu lato, but support for several clades varies among approaches – namely Equus sensu Eisenmann, Allohippus, and “Sussemiones”. This instability is primarily driven by differential placement of the core “stenonid” clade either outside of crown Equus or within Equus in a position on the stem of the zebra-ass clade. The unstable tree topology warrants greater examination, and suggests that efforts to split Equus into multiple genera may be premature. This analysis is the first to integrate molecular and morphological data in this clade and represents a major step towards resolving the phylogeny of Equini.

Ethnogeology, Sense of Place, and Place Theory as a Framework for Advancing Multidisciplinary Research in Cave and Karst Science 

Ángel García, James Madison University

Ethnogeology is the study of geology through a place-based epistemology rooted location and sense of place. Often, it draws traditional knowledge systems and incorporates methodologies from field ethnography (anthropology), place theory (cultural geography and environmental psychology), and field geology to examine how diverse cultures understand, interpret, and interact with Earth systems. Ethnogeological research typically centers on specific communities and their unique environmental perspectives, tapping into the deep knowledge held by local community members and the ways they engage with their surrounding landscapes. This integrative approach could provide a comprehensive understanding of geological settings, strengthen environmentally grounded local practices, and support the development of more inclusive and culturally relevant geoscience pedagogy and research. In this talk, we explore how ethnogeology functions as a theoretical and methodological framework in studies of paleoclimate, geomorphology, community-based research, and both formal and informal education related to cave and karst science. Furthermore, we discuss how ethnogeology offers a lens through which to examine multiple dimensions of the relationship between karst geology and society.

Title: Modeling Carbon-Rich Protoplanets: Implications of Graphite in super-Earths and sub-Neptunes

Authors: Aletta Bartok, Marc Hirschmann

Keywords: Super-Earths, Sub-Neptunes, Graphite, Planetary Geochemistry, Python, Icy Moons.

Abstract: As the most extensively studied exoplanets, super-Earths and sub-Neptunes represent a critical component in planetary geochemistry. Planets forming within the soot-line, which are rich in carbon, potentially graphite, are assumed to deviate from the standard silicate-dominated geochemical protoplanetary models. This study uses a zero-dimensional Python model, optimized for batch processing via the Minnesota Supercomputing Institute (MSI). To look at the effects of increased soot in these planetary bodies, we have modified the existing thermodynamic framework to incorporate graphite into the melt-phase equilibrium and introduce a new reaction with graphite and oxygen gas, making carbon dioxide gas in the model’s atmosphere. Our results indicate that the inclusion of a graphite-rich melt allows hydrogen gas to dominate the atmosphere while simultaneously suppressing methane gas. This work provides the necessary basis for modeling carbon-rich environments, offering a new lens through which to evaluate the geochemistry of exoplanets and local icy moons. 

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Title: Investigation of possible sources of 'ruby like' detrital garnets in the Hale River, Central Australia

Authors: Shenandoah Verstraete, Donna Whitney, Sara Hanel, Christian Teyssier, Jennifer Mitchell

Keywords: Garnet

Abstract: In the 19th century, Ruby Gap, Australia experienced a ruby rush, when abundant, gem-like crystals were found in the sand of the Hale River. These ‘rubies’ were in fact mistaken and were actually garnets. The quartzite rocks surrounding the area however, did not contain any garnets, so the source of the garnets in the river is not yet clear. Garnet rich sand was collected from 1 location along the Hale River in Ruby Gap, and 3 other locations upstream. The color and therefore compositions and textures of these garnets vary. By analyzing the inclusions in the garnets and their zoning, the detrital garnets can be compared to the garnets found in outcrops upstream. By comparing the detrital garnets to the outcrop garnets and to scientific literature in the area, the compositional similarities and differences will indicate where the garnets that make up the garnet rich sand in the Hale River are coming from and possible drainage paths to the river can be tentatively traced.

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Title: Mineralogical Properties of the Bruna Gneiss from Central Australia

Authors: Elliot LaValley, Donna Whitney

Keywords: Bruna Gneiss, Myrmekite, K-Feldspar, Petrographic microscope, Electron microprobe

Abstract: Mountain belts commonly contain tectonically discrete, but connected domains of thrust belts and domes. The Bruna Gneiss of Central Australia connects the contractional Ruby Gap Duplex and the extensional Entia dome, both of the same age. Analysis of the Bruna Gneiss’ deformation and metamorphism can link the history of the distinct tectonics of this region. The protolith of the gneiss is unknown and analysis of the large feldspar crystals may distinguish between an igneous (plutonic or volcanic) or sedimentary origin. In most of the gneiss, feldspar megacrysts are light colored. Near contacts between the Bruna Gneiss and underlying Entia dome, Bruna’s feldspars exhibit different characteristics: they are larger, blue, and have thin, light-colored rims. The mineralogy and textures of the gneiss and its feldspar megacrysts were explored with thin sections using a petrographic microscope. An abundance of myrmekite (plagioclase and quartz intergrowth) was found along the edges of K-feldspars, especially within the white rim of the blue feldspar. Some feldspar megacrysts contain fractured garnets, and the gneiss contains various accessory minerals, such as large zircons (up to 0.3 mm), that may point to the origin of the gneiss. An electron microprobe was used to determine the composition and zoning of feldspar megacrysts, as well as identities and locations of important minerals such as zircon. The feldspars do not show strong zoning in major elements. An abundance of barium was found in both of the large analyzed feldspar crystals. The blue feldspar has a Ba-rich rim, but the regular feldspar has overall higher amounts of Ba.

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Title:  Investigating Rock Magnetic Changes during Laboratory-based Hydrothermal Alteration of Basalts

Authors: Justin Waterman, Jacob Anderson, Josh Feinberg

Keywords: hydrothermal, geophysics, rock magnetism, geochemistry, Long Valley Caldera

Abstract: Long Valley Caldera (LVC), California, hosts an active geothermal system with numerous surface expressions of active and fossil hydrothermal activity that occurred since the caldera’s formation at 767 ka. Recent aeromagnetic and thermal imaging surveys by the US Geological Survey show that aeromagnetic lows within LVC are co-located over areas of active hydrothermal activity. Associations between hydrothermal activity and aeromagnetic anomalies were identified at least 50 years ago, but the underlying processes that give rise to this association remain poorly understood. This project explores how hydrothermal activity in volcanic settings influences airborne magnetic surveys, with the aim of constraining the processes and longevity of hydrothermal activity. 

Hydrothermal fluids can modify magnetic mineral assemblages by processes such as dissolution, oxidation, and/or nucleation and growth of new magnetic minerals. Preliminary magnetic measurements on LVC basalts show a progressive loss of magnetic minerals with proximity to active hydrothermal centers. Here we report preliminary results from laboratory-based hydrothermal experiments on LVC rocks to test the hypothesis that hydrothermal fluids dissolve and alter primary magnetic minerals in host rocks, producing magnetic lows. This work addresses a gap in our understanding of how hydrothermal fluid circulation impacts the geophysical expression of magnetic mineral assemblages in volcanic rocks. Magnetic measurements, fluid chemistry measurements, and mineral characterization observations on LVC basalt standards before and after hydrothermal alteration experiments will quantify changes to mineral assemblages. Basalt standards will be placed in separate acid digestion bombs with a fluid that approximates current LVC geothermal reservoir composition and conditions (~170°C). Alteration products will be examined after various time intervals to document the progress of hydrothermal alteration reactions. We expect to observe decreasing saturation magnetization (Ms) and an increasing coercivity (Hc) in our altered material following the removal of primary (titano) magnetite and alteration to secondary magnetic phases, such as maghemite. This project’s intellectual merit is far reaching because it will define mineral processes that commonly occur at terrestrial volcanic sites worldwide and perhaps on other planetary bodies.

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Title:  Constraining the 3-D Geometry of the Duluth Complex, MN, Using Magnetic Fabrics and Paleomagnetic Data

Authors: Kathryn Akin, Nicholas Swanson-Hysell

Keywords: Paleomagnetism, Rock Magnetism, Magnetic Fabrics, Mafic Intrusive Complex, Duluth Complex

Abstract: The Midcontinent Rift developed within the interior of Laurentia during a period of extension and magmatism from 1109 Ma to 1084 Ma (Swanson-Hysell et al., 2019). Emplaced during the development of the Midcontinent Rift, the Duluth Complex is interpreted as the second-largest exposed mafic intrusive complex on Earth. The Duluth Complex is composed of an anorthositic series and a layered series of gabbro and troctolite cumulates (Figure 1; Miller et al., 2002). Many studies have been conducted on the geology, mineralization, structure, timing, and mechanisms of emplacement of the Duluth Complex and nearby Beaver Bay Complex and North Shore Volcanic Group, but there is still some uncertainty surrounding the thickness, and therefore overall volume, of the Duluth Complex. The tilt of the Duluth Complex is not well-constrained in the anorthositic series, given the absence of macroscopic igneous foliation, so this research is focused on developing data on the magnetic fabrics of the Duluth Complex along a transect to constrain the igneous foliation and to use these data to develop new estimates of the tilt and thickness of the intrusion. Anisotropy of magnetic susceptibility (AMS) is sensitive to changes in mineral alignment and can be used to constrain igneous foliation (Schmidt et al., 2007). Remanent magnetization data collected and compared to the expected directions of contemporaneous volcanics will be used to gain further insight into tilt. Together, the new susceptibility and remanence data will provide important petrophysical information for interpreting upcoming USGS aeromagnetic surveys currently being flown in northeastern Minnesota.

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Title: Paleomagnetic Properties of the Crocodile Lake Gabbro, Duluth Complex, Minnesota

Authors: Marcus Lorenzen

Keywords: Duluth Complex, Paleomagnetism

Abstract: The Crocodile Lake Gabbro developed in the early stages of the Laurentian Midcontinental Rift, which developed during a period of intercontinental extension and magmatism from 1109 Ma to 1084 Ma (Swanson-Hysell et al. 2019). Emplaced during the development of the rift, the Crocodile Lake Gabbro and many associated mafic intrusive formations cooled and are presently the second largest intrusive mafic formation, known as the Duluth Complex. The Crocodile Lake Gabbro formed as an early-series intrusion of the Duluth Complex circa 1105 Ma and is composed of a coarse-grained gabbro member and a fine-grained ferrodiorite member, with associated cross-cutting dikes. We conducted experiments in the Institute for Rock Magnetism to investigate both the remanent and induced magnetic properties of the rocks as well as a potential magnetic fabric. The remanent and induced magnetism was compared for each sample to solve for its associated Koenigsberger ratio, which compares remanent and induced magnetization for rocks. The remanent magnetic vector was also used to help constrain the movement of Laurentia during the late Mesoproterozoic before the assembly of Rodinia (Swanson-Hysell et al. 2023). We also found some preferential orientation and crystal alignments within the rocks using anisotropic magnetic susceptibility (AMS) that align with igneous foliation measurements in the region. (Schmidt et al., 2007). The susceptibility and remanence data will provide important petrophysical data for interpreting upcoming aeromagnetic surveys being flown in northeastern Minnesota while also contributing to the Magnetics Information Consortium (MagIC).

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Title: Isolating and characterizing Pb-tolerant bacteria from sunflower roots grown in metal contaminated soil

Authors: Michael Birch-Tanzer, Madeline R. Taylor, Cara M. Santelli

Keywords: Lead (Pb), soil microbes, heavy metal tolerance, rhizosphere

Abstract: Rhizosphere bacteria that live in close association with plant roots play an important role in metal transformations that allow metals, like lead (Pb), to become bioavailable for plants. Understanding microbe-metal interactions in plant rhizospheres is critical for human health, bioremediation potential, and critical metal acquisition. We aim to isolate and characterize a microbe from a plant rhizosphere in Pb-polluted soil that could be used for microbe-plant testing with Pb hyperaccumulating plants like sunflowers. Here, we enriched soil bacteria from sunflower (Helianthus annuus) roots that were grown at Pig’s Eye Regional Park (St. Paul, MN) in soil with average Pb concentrations ~305 ppm (confirmed via X-ray fluorescence spectrometry). We hypothesize that these microbes will have a higher average Pb resistance, but their growth will still slow or stop at Pb concentrations significantly higher than their original soil environment. Enrichments in Hoaglands, LB, and R2A media from root inoculates resulted in 3 unique cultures that were identified using targeted bacterial 16S rRNA gene amplification as a Pseudomonas chlororaphis isolate, an Agromyces terreus isolate, and a bi-culture of Erwinia billingiae and Pantoea dispersa. We characterized bacterial Pb tolerance with 4 Pb treatments in LB media: 0, 0.5, 1.0, and 5.0 mmol/L of PbNO3. After 2 days in liquid media, the Pseudomonas sp. exhibited the highest growth of all cultures, with only a 13% growth reduction at 5.0 mmol Pb compared to 0 mmol. The Erwinia sp. and Pantoea sp. bi-culture exhibited 39% lower growth than the Pseudomonas sp. and a 41% growth reduction at 5.0 mmol Pb. The Agromyces sp. grew very little in comparison to the other cultures, even at low Pb concentrations. We also assessed potential plant pathogenic effects with a virulence assay by inoculating pears (Pyrus communis 'Anjou') with 100ul of 0.1 OD cultures. We plan to grow up the Pseudomonas chlororaphis Pb-tolerant strains for further genomic analysis and advanced analysis of strain interaction with plants using RhizoChip technology at the Environmental Molecular Science Laboratory.

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Title: Simulated Effects of Drainage-Ditch Infilling on Wetland Extent

Authors: Uma Ashrani, Andrew Wickert

Keywords: wetlands, agriculture, hydrology, wetland restoration

Abstract: Artificially constructed flow networks (drainage ditches) drain surface water to facilitate farming, but they reduce the area of natural wetlands that are critical for ecosystem health, water filtration, carbon storage, and flood protection. Motivated by case studies in wetland restoration, we aim to systematically model the effects of ditches on wetland extent while evaluating which ditches are protecting nearby infrastructure from inundation. We began by correcting drainage-ditch vector data to align with ditch channels in LiDAR topography, and we hydroconditioned this topography to permit flow continuity under bridges and through culverts. With these data products in hand, we developed methods in GIS to simulate damming ditches. These were applied to the ditch networks in the Minneopa Creek HUC10, located in southern Minnesota. Surface-water depth across the region was modeled using the RichDEM depression-filling algorithm, and was compared between the base case topography (no ditches dammed) and each infilling scenario (one ditch dammed at a time). This comparison allows us to isolate the impacts of each ditch by displaying where water depth would increase as a result of damming the ditch. Model results show that damming certain ditches would cause expansion of present-day water bodies in some cases and restoration of historic wetlands in others. These tools are intended to be used in restoration planning for any region with mapped ditches; the results of infilling a particular ditch can be overlaid with the present-day land use to determine whether infrastructure or farmland would be flooded. Additionally, pre-processing methods improve the accuracy of digitized ditch data and offer tools for hydroconditioning/digital culvert removal in DEMs.

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Title: TBD

Authors: Louis Miller, G.-H. Crystal Ng

Keywords: TBD

Abstract: TBD

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Title: Assessing Environmental Effects of Cover Crop Biomass in Southern Minnesota Farm Systems

Authors: Robert Fowler, Anna M. Cates, Jeffrey Strock, Jeffrey Vetsch

Keywords: Soil, edge-of-field effects, conservation agriculture, cover crops, ecosystem services, erosion, nutrient loss, nitrogen leaching, water quality

Abstract: Cover crops (CC) are an integral practice in conservation agriculture. However, there exists  uncertainty at which planting rates and subsequent biomass levels CCs deliver measurable ecosystem services. Controlling soil erosion and subsurface inorganic nitrogen losses are of particular interest when including CCs in rotation planning. To assess the ecosystem services of increasing CC biomass levels, we planted cover crops at multiple seeding rates in plots established in Saint Paul, Waseca and Lamberton, MN in fall 2024. Cereal rye treatments of 10, 20, 40, and 80 lb/ac and oat/radish treatments of 10+1, 20+2, 40+4 and 60+6 lb/ac were compared to a fallow control in a randomized complete block design with four replicates. Mesh erosion mats were used to compare water-borne sediment movement in all treatments. Ceramic cup lysimeters were installed in St. Paul and Waseca to determine subsurface NO3- losses under selected treatments and the control. Soil N balance was investigated using fall and spring 3-depth soil cores. Cover crop aboveground biomass was harvested and tested for N content to establish uptake. Another portion of this study involved measuring arbuscular mycorrhizal fungi (AMF) legacy following select CC treatments in a subsequent soybean cash crop. We measured concomitant soil health parameters such as aggregate stability, organic nitrogen (ACE), potentially mineralizable carbon (PMC) and soil phosphate. The focus of this poster will be the relationship between CC biomass, sediment losses, NO3- leaching and soil N economy. Data from the completed 2024-25 season will be presented.

4:05pm - 4:20pm

Title: Impact of Reaction-Driven Fracturing on Fluid Flow and Hydration in the Lithosphere

Authors: Jeremiah McElwee, Ikuko Wada, Kazuki Yoshida, Atsushi Okamoto

Keywords: Hydration, Subduction, Reaction-Driven Fracturing, Serpentinization

Abstract: At tectonic plate boundaries, fluids may hydrate the lithosphere, producing hydrous minerals such as serpentine and brucite. However, the extent of hydration is likely limited by the local permeability of the lithosphere. Experimental evidence indicates that the solid volume increase associated with many hydration reactions may induce fracture, enhancing the permeability of the hydrating rock. This “reaction-driven fracturing” accelerates hydration by creating new fluid pathways and is potentially critical for extensive hydration of the lithosphere. Using distinct element method simulations that couple fluid flow, a fluid consuming volume increasing reaction, and mechanical deformation, we have systematically investigated the impact of several key parameters, such as differential stress, confining pressure, and the strength of hydrous reaction products, on reaction-driven fracturing. These simulations indicate that reaction-driven fracturing can either localize fluid flow or promote spatially extensive hydration. Comparison of simulation results to geophysical and geologic observations of hydration at plate boundaries suggests that reaction-driven fracturing may help explain the variable degrees of hydration observed in the mantle wedge corner and along faults within the oceanic plate.

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4:20pm-4:35pm

Title: A field-inspired, systematic investigation of conduit network impacts on spring flow in karst aquifers

Authors: Jenny Huang; Marco Dentz; Jannes Kordilla; John Barry; Christian Langevin; Peter K. Kang

Keywords: Karst aquifers; conduit network; numerical modeling; spring hydrograph

Abstract: Karst aquifers– triple-porosity systems composed of conduits, fractures, and the rock matrix–are particularly vulnerable to contamination due to direct surface connectivity via sinkholes and open fractures and rapid transport through preferential pathways. Effective protection and remediation of these groundwater systems necessitates accurate characterization of flow and transport. However, accurate modeling of flow and transport in karst aquifers is challenging due to the partitioning of recharge between the bedrock and the embedded conduit network. These conduit networks serve as both preferential flow paths and additional storage reservoirs. The structural and geometric properties of these networks thus impact flow and transport behavior, but there has not been a systematic, quantitative study of how conduit network structure and geometry impact spring hydrographs and breakthrough curves in naturalistic field conditions. In this field-inspired modeling study, we attempt to identify key geometric and structural properties of conduit networks that control flow and transport in karst aquifers and use these insights to constrain our understanding of a nitrate and chloride-impacted karst aquifer in Southeastern Minnesota. 

We systematically vary network structure (e.g., tortuosity, connectivity), conduit geometry (e.g., diameter distribution), and recharge distribution for a field-inspired conduit network. We explicitly model conduit flow with the model openKARST coupled with a linear reservoir model to represent matrix controls on conduit flow. To identify key network properties that impact spring flow, we quantify the differences in spring hydrograph behavior as a function of network properties, with a particular focus on identifying the conditions under which conduit geometry can be simplified or ignored when modeling spring flow. Based on the simulation results of synthetic yet realistic conduit systems, we attempt to characterize the key properties of the conduit network of a karst aquifer in Southeastern Minnesota and validate these properties by faithfully simulating observed spring hydrographs. Future work will incorporate solute transport to investigate the impact of conduit network structure and geometry on breakthrough curve behavior.

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4:35pm-4:50pm

Title: Dinoflagellate Cyst Assemblages in Surface Sediments of the Chukchi Sea

Authors: Vincy Y Winifred, Vera Pospelova, Evangeline Fachon, Kenneth Neil Mertens and Donald M Anderson

Keywords: Dinoflagellate cysts, Chukchi Sea

Abstract: Dinoflagellates are marine, ecologically versatile single-celled protists that contribute significantly to ocean primary productivity. Some species produce preservable organic-walled resting cysts that act as a repository of past sea-surface environmental conditions. Dinoflagellate cysts are widely used as proxy indicators of water- mass conditions, as their abundance and species composition reflect variations in sea-surface temperature (SST), salinity (SSS), sea-ice cover (SIC), nutrient availability, and pollution. 

Here, we present the initial results of an ongoing comprehensive study of dinoflagellate cyst assemblages in the northern Chukchi Sea. The Chukchi Sea, located on the western margin of the Arctic Ocean, forms a critical link between the North Pacific and Arctic Oceans. 

Fifty-four surface sediment samples were collected during the 2018–2019 Distributed Biological Observatory-Northern Chukchi Integrated Survey cruise and processed using a standardized palynological preparation technique. Preliminary results reveal diverse dinoflagellate cyst assemblages characterized by taxa commonly found in productive Arctic and sub-Arctic environments, including Operculodinium centrocarpum sensu Wall and Dale (1966), Spiniferites spp., Spiniferites elongatus, Brigantedinium spp., and Islandinium minutum. The estimated total dinoflagellate cyst concentrations range from ~2,600 to 21,800 cysts g⁻¹, averaging around ~6,100 cysts g⁻¹. 

Further analyses of dinoflagellate cyst assemblages and concentrations, together with modern environmental parameters, using multivariate statistical approaches will help identify the primary environmental controls on cyst distributions and improve the calibration of these microfossils for high-resolution paleoenvironmental reconstructions in the Chukchi Sea.

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4:50pm-5:05pm

Title: Tower-Based Flux Observations of CO2 and CO in Greater New York Capture Competing Roles of Fossil Fuel Emissions and the Urban Biosphere

Authors: Trey Maddaleno, Dylan B. Millet, Michael P. Vermeuel, Katelyn L. Richard, Jeff Peischl, Emily B. Franklin, Delphine K. Farmer, Róisín Commane, Timothy J. Griffis

Keywords: Urban, emissions, atmospheric science, eddy covariance

Abstract: Carbon dioxide (CO2) and carbon monoxide (CO) are key urban pollutants: CO2 as a climate-warming greenhouse gas, and CO as both a harmful criteria pollutant and a primary player in atmospheric oxidation, causing an indirect warming effect. Urban emissions are shifting away from more traditional sources such as traffic and towards less characterized sources - challenging our understanding of urban air quality and source behavior. Eddy covariance (EC) measurements allow direct quantification of surface-atmosphere fluxes, providing valuable information for characterizing the underlying temporal and spatial drivers of emissions and advancing model predictions. However, this potential is underutilized, as few studies have combined direct flux measurements of both CO2 with CO. Here, we present EC-derived CO2 and CO fluxes across multiple seasons over an urban footprint during the Fluxes of Reactive Organic Gases in New York (FROG-NY) project. Measurements alternated between two heights (32.5 and 60 m) on a cellular tower in greater New York and included fast, simultaneous measurements of CO2 and CO alongside a suite of other measurements. Results show net upward fluxes for both CO2 and CO across the spring, summer, and winter measurement periods. The magnitude of CO2 fluxes was weakest in the spring and early summer period. Here, we will interpret the urban CO2 and CO fluxes with respect to the factors controlling variability across seasons and diurnally, and compare our results with emissions estimates from a bottom-up emissions inventory.