ItemAttributes of Organic Phosphorus Exported from a Central Indiana Agricultural Watershed: Effects of Season and Hydrologic Flowpath(2023-05) Pitcock, Rebecca Jo; Jacinthe, Pierre-Andre; Filippelli, Gabriel; Wang, LixinThe export of phosphorus (P) from agricultural watersheds has been extensively investigated but monitoring efforts have generally focused on inorganic P (Pi or soluble reactive phosphorus [SRP]), the P fraction thought to be immediately available to algae. However, in settings where no-till management is implemented and organic matter accumulates on soil surface, the amount of organic P (Po) in agricultural drainage waters can be significant and may represent another important P source to fuel algal growth in receiving water bodies. From a 2018 monitoring study at a Central Indiana agricultural watershed, measured total P and SRP loss amounted to 1.22 and 0.17 kg P/ha/year, respectively, indicating that the bulk (84%) of P exported from that watershed was in organic form. Results also showed that tile drainage was the main pathway for P transport (96% of Po loss). In light of these observations, the bioavailability of Po in agricultural drainage waters was investigated in 2019, and the effect of hydrologic flow path (surface versus subsurface flow) on the biochemical attributes of Po was examined. In these assessments, the iron strip method and a suite of enzymatic assays were used to gain a better understanding of the chemical composition of the exported Po. Higher concentration of labile Po was consistently measured in tile discharge than in surface runoff (59% versus 38% of the total bioavailable P). Further, the concentration of EHP (enzymatically hydrolysable P), in the form of monoester, diester, and phytate compounds, was highest during the summer season, for both tile and surface pathways. This elevated bioavailability of Po during the summer is a concern because, in combination with favorable water temperature and solar radiation during that period, this could lead to enhanced Po mineralization and release of Pi, resulting in further algal proliferation and continued degradation of water quality. Considering the high prevalence of tile drainage in agricultural landscapes of the US Midwest, this finding underscores the need for further investigation of the impact of land management and climate on the speciation and bioavailability of Po in the region’s agricultural waters. ItemExploring Competing Theories of Viscous Emulsion and Fractional Crystallization of the Impact Melt that Formed the Sudbury Igneous Complex(2023-01) Horman, Alexandra Rose; Macris, Catherine A.; Barth, Andrew P.; Gilhooly, William P., III.The Sudbury Igneous Complex (SIC) in Sudbury, Canada is a remnant geologic structure from a meteor impact that occurred ~1.85 Ga. The impact produced ~30,000 km3 of superheated melt which reached >2200 °C. The existing SIC is composed of three compositionally distinct layers, norite, quartz gabbro, and granophyre, which stretch the entire lateral distance of the complex. The presentation of layers in the SIC is unusual for impact melts, and the crystallization path has been debated by scientists. The SIC differs from more common layered mafic complexes because of its intermediate composition, crustal isotopic signature, and large volume of granophyre. This thesis is an investigation of some of the main theories surrounding the SIC and how it crystallized to form such distinct layers. There are two main theories of how the SIC formed its compositionally distinct layers: (1) fractional crystallization and (2) separation by viscous emulsion. The viscous emulsion theory involves isolated droplets of melt separating from the surrounding melt body due to differences in viscosity and density, similar to an emulsion of oil and water. In this study, viscous emulsion theory was investigated experimentally by heating samples of rock from the SIC to the extreme temperatures associated with the Sudbury impact, and then analyzing the cooled experimental products using electron microscopy to determine if there was evidence of textures that would be consistent with expectations for a viscous emulsion. Fractional crystallization was investigated by modeling using the vii software EasyMELTS to evaluate compositions from the SIC to estimate how they would crystallize according to the temperature, pressure, and other properties of the melt. There was no textural evidence of a viscous emulsion found in the experimental products. The models produced compositions similar to what is seen in the SIC but had limited application to fractional crystallization theory. ItemQuantifying the Biogeochemical Impact of Land Plant Expansion in the Mid Devonian and Implications in Marine Anoxic Events(2022-12) Smart, Matthew Stephen; Filippelli, Gabriel; Gilhooly, William III; Barth, Andrew; Wilson, JeffreyThe evolution of land plant root systems occurred stepwise throughout the Devonian, with the first evidence of complex root systems appearing in the mid-Givetian. This biological innovation provided an enhanced pathway for the transfer of terrestrial phosphorus (P) to the marine system via weathering and erosion. This enhancement is consistent with paleosol records and has led to hypotheses about the causes of marine eutrophication and mass extinctions during the Devonian. To gain insight into the transport of P between terrestrial and marine domains, presented here are geochemical records from a survey of Middle and Late Devonian lacustrine and near lacustrine sequences that span some of these key marine extinction intervals. Root innovation is hypothesized to have enhanced P delivery and results from multiple Devonian sequences from Euramerica show evidence of a net loss of P from terrestrial sources coincident with the appearance of early progymnosperms. Evidence from multiple Middle to Late Devonian sites (from Greenland and northern Scotland/Orkney), reveal a near-identical net loss of P. Nitrogen and Carbon isotopes from a subset of these lakes confirm elevated input of terrestrial plant material concurrent with P perturbations. Terrestrial P input appears to be episodic in nature, suggesting land plant expansion was driven by an external catalyst in the study region. All sites analyzed are temporally proximal to significant marine extinctions, including precise correlation with the Kačák extinction event and the two pulses associated with the Frasnian-Famennian (F/F) mass extinction. The episodic expansion of terrestrial plants appears to be tied to variations in regional and global climate, and in the case of the F/F extinction, also to atmospheric changes associated with large scale volcanism. Using P data presented here as an input into an Earth system model of the coupled C-N-P-O2-S biogeochemical cycles shows that globally scaled riverine phosphorus export during the Frasnian-Famennian mass extinction generates widespread marine anoxia consistent with the geologic record. While timing precludes land plants as an initiating mechanism in the F/F extinction, these results suggest they are implicated in every marine extinction event in the Mid to Late Devonian. ItemAnalysing Urban Air Pollution Using Low-Cost Methods and Community Science(2022-12) Heintzelman, Asrah; Filippelli, Gabriel; Moreno-Madriñan, Max J.; Wilson, Jeffrey S.; Wang, Lixin; Druschel, Gregory K.Rise in air pollution resulting in negative health externalities for humans has created an urgent need for cities and communities to monitor it regularly. At present we have insufficient ground passive and active monitoring networks in place which presents a huge challenge. Satellite imagery has been used extensively for such analysis, but its resolution and methodology present other challenges in estimating pollution burden. The objective of this study was to propose three low-cost methods to fill in the gaps that exist currently. First, EPA grade sensors were used in 11 cities across the U.S. to examine NO2. This is a simplistic way to assess the burden of air pollution in a region. However, this technique cannot be applied to fine scale analysis, which resulted in the next two components of this research study. Second, a citizen science network was established on the east side of Indianapolis, IN who hosted 32 Ogawa passive sensors to examine NO2 and O3 at a finer scale. These low-cost passive sensors, not requiring power, and very little maintenance, have historically tracked very closely with Federal Reference Monitors. Third, a low-cost PurpleAir PA-II-SD active sensors measuring PM2.5 were housed with the citizen scientists identified above. This data was uploaded via Wi-Fi and available via a crowd sourced site established by PurpleAir. These data sets were analyzed to examine the burden of air pollution. The second and third research studies enabled granular analyses utilizing citizen science, tree canopy data, and traffic data, thus accommodating some of the present limitations. Advancement in low-cost sensor technology, along with ease of use and maintenance, presents an opportunity for not just communities, but cities to take charge of some of these analyses to help them examine health equity impacts on their citizens because of air pollution. ItemInvestigating the Effects of Synoptic-Scale Climatic Processes on Local-Scale Hydrology by Combining Multi-Proxy Analyses of Lacustrine Sediments and Instrumental Records(2022-09) Gibson, Derek Keith; Bird, Broxton; Gilhooly, William, III; Jacinthe, Pierre-André; Licht, Kathy; Wang, XianzhongPaleoclimate records from North and South America were used to develop a holistic understanding of global paleo-hydroclimatic drivers across a range of boundary conditions. Here, geophysical analysis of lacustrine sediment stratigraphy at Lago de Tota, Boyaca, Colombia provided evidence for significant lake-level fluctuations through the late Quaternary and produced a record that potentially spans the last 60 ka. Seismic data revealed a series of off-lap and on-lap sequences in the upper ~20 m of sediments that indicated large amplitude changes in lake-level, driven by variability in the mean latitude of the Intertropical Convergence Zone as controlled by insolation- and ocean circulation-driven hemispheric temperature gradients during glacial/stadial and interglacial/interstadial events. In North America, late Holocene flood recurrence in the Midwest and Holocene changes in the mean latitude of the polar front jet stream were investigated through multi-proxy examinations of sediment cores collected from swale lakes in northern Kentucky and southern Indiana, and a glacially formed kettle lake in northern Indiana. These results showed that the midlatitude jet stream was displaced to the south during the late Holocene, which increased the amount of Midwestern precipitation sourced from the northern Pacific and Arctic, especially during prolonged cool conditions. During these cool periods, when atmospheric flow was meridional and a greater amount of precipitation was delivered from the northerly sources, Ohio River flooding increased. During warm conditions, when clockwise mean-state atmospheric circulation advected southerly moisture from the Gulf of Mexico into the Midwest, flooding on the Ohio River decreased. At present, streamflow in the Midwest is demonstrated here to be generally increasing, despite atmospheric conditions typically associated with reduced streamflow in the paleo-record, due in part to increasing precipitation and modern land-use dynamics. Together, these studies demonstrate the sensitivity and vulnerability of local-scale hydrological processes to synoptic climate change. ItemExamining Ecosystem Drought Responses Using Remote Sensing and Flux Tower Observations(2022-09) Jiao, Wenzhe; Wang, Lixin; Novick, Kimberly A.; Filippelli, Gabriel; Wang, Honglang; Li, LinWater is fundamental for plant growth, and vegetation response to water availability influences water, carbon, and energy exchanges between land and atmosphere. Vegetation plays the most active role in water and carbon cycle of various ecosystems. Therefore, comprehensive evaluation of drought impact on vegetation productivity will play a critical role for better understanding the global water cycle under future climate conditions. In-situ meteorological measurements and the eddy covariance flux tower network, which provide meteorological data, and estimates of ecosystem productivity and respiration are remarkable tools to assess the impacts of drought on ecosystem carbon and water cycles. In regions with limited in-situ observations, remote sensing can be a very useful tool to monitor ecosystem drought status since it provides continuous observations of relevant variables linked to ecosystem function and the hydrologic cycle. However, the detailed understanding of ecosystem responses to drought is still lacking and it is challenging to quantify the impacts of drought on ecosystem carbon balance and several factors hinder our explicit understanding of the complex drought impacts. This dissertation addressed drought monitoring, ecosystem drought responses, trends of vegetation water constraint based on in-situ metrological observations, flux tower and multi-sensor remote sensing observations. This dissertation first developed a new integrated drought index applicable across diverse climate regions based on in-situ meteorological observations and multi-sensor remote sensing data, and another integrated drought index applicable across diverse climate regions only based on multi-sensor remote sensing data. The dissertation also evaluated the applicability of new satellite dataset (e.g., solar induced fluorescence, SIF) for responding to meteorological drought. Results show that satellite SIF data could have the potential to reflect meteorological drought, but the application should be limited to dry regions. The work in this dissertation also accessed changes in water constraint on global vegetation productivity, and quantified different drought dimensions on ecosystem productivity and respiration. Results indicate that a significant increase in vegetation water constraint over the last 30 years. The results highlighted the need for a more explicit consideration of the influence of water constraints on regional and global vegetation under a warming climate. ItemQuantifying the Responses of Vegetation to Environmental Stresses(2022-09) Lanning, Matthew L.; Wang, Lixin; Wang, Xianzhong; Novick, Kimberly Ann; Jacinthe, Pierre-André; Gilhooly, William P.I examined interactions between plants and the environment they live in along the soil-plant-atmospheric continuum and addressed the effects of drought and acid deposition on plant water use. Using a novel stable isotope technique, I showed that plant water source utilization can be modulated in some species based on the soil and atmospheric conditions they experience, whereas others only access a single subsurface water source. By modeling cuticular conductance in multiple plant species, I showed that the variability of cuticular conductance across species is largely related to the changes in leaf water potentials between pre-dawn and midday measurements collected in field studies. I also assessed the individual and combined effects of soil water stress and atmospheric water stress on plant productivity by developing a new methodology, which can be used across scales. In doing so, I found that in deciduous broad-leaf forests, periods of high vapor pressure deficit caused sufficient hydraulic stress to reduce plant productivity more than low soil water content alone, and often reduced productivity to levels equal to periods of both low soil water stress and high vapor pressure deficit. Utilizing historical data from a whole forest acidification experiment, I was able to link the stress of nutrient deficiencies caused by acid deposition (specifically calcium) to increases in plant water utilization. This was the first observation of such an effect at the ecosystem scale and could have significant implications for understanding water availability in the future. Finally, I assessed a common method for extracting cellulose from tree rings for isotope analyses, which is often used to determine the historical water use efficiency of plants. I was able to determine chemical alteration to the cellulose molecule using stable isotope measurements and spectroscopy. The chemical modification seems to be systemic and therefore could be addressed through mathematical corrections to existing data. Having accurate values of plant water use efficiency is extremely important for understanding how different stressors in the past changed the way plants used their water resources. My series of studies provide new insights and tools to evaluate the plant-environment interactions in current and future environments. ItemNew Insights Into Impact Glass Formation and Evolution Using Machine Learning and Aerodynamic Levitation Laser Heating Experiments(2022-09) Marrs, Ian James; Macris, Catherine; Barth, Andrew; Druschel, GregoryImpact processes, where a meteor strikes a planetary body’s surface, are ubiquitous in the Solar System. These highly energetic events require study by both computational methods and experimental investigation. An impact process of particular interest to our study is the impact plume, a collection of vaporized rock and superheated gases that is produced during an impact event. Tektites are silica rich (roughly rhyolitic), extremely dry, and often contain both lechatelierite inclusions (amorphous SiO2) and flow textures (schlieren) and are an impact product of particular interest to this study. Tektites likely form either very early in the impact process or within the impact plume itself as condensates, and therefore offer a unique insight into the early stages of the impact cratering process. Here, we present both the results of the statistical analysis of published tektite geochemistry and the geochemical analysis of a variety of glasses produced in an aerodynamic levitation laser furnace. The major findings of the statistical analysis are that the variance of tektite geochemistry is broadly controlled by MgO, CaO, K2O, and Na2O, that the Australasian strewn field (an extensive region of tektite distribution) is best subdivided into five geochemical subgroups, and that random forest classification models can predict the strewn field or geochemical subgroup of an unknown tektite with >94% accuracy. In terms of our heating experiments, in nearly all cases, Na2O and K2O are rapidly lost from the melt due to evaporation, while Al2O3, CaO, and TiO2 become progressively enriched. Volatility is far more dependent on peak heating temperature than on heating time. Additionally, the chemical constituents of basalts are less readily volatilized than those of rhyolites or loess, with few exceptions. We also find that the volatility of the chemical constituents of non-standard samples is far more variable than for standard samples and that oxygen fugacity has a strong influence over elemental volatility in the aerodynamic levitation laser furnace. Changes in oxygen fugacity can either result in variable, exaggerated, or even opposite volatility trends depending on the material and oxide in question. ItemA High-Resolution Study of Local Diagenetic Effects on the Geochemistry of the Late Ordovician Kope Formation(2022-09) Becerra, Evelyn S; Gilhooly, William P., III; Licht, Kathy; Filippelli, GabrielThe Ordovician (485-444 Ma) was a highly dynamic period, characterized by significant evolutionary and climatic change. Paleozoic fauna which evolved during the Great Ordovician Biodiversification Event (GOBE) populated extensive epicontinental seaways. Major sea level fluctuations during The Hirnantian glaciation are believed to have led to a mass extinction event at the End Ordovician. However, a reassessment of Early Paleozoic fossil assemblages suggests the onset of extinctions began in the mid-Katian, ~3 million years before the Hirnantian. The Kope formation, within the North American succession of the Katian, was deposited during the peak biodiversification of the GOBE at the point which a biological crisis begins. The well-studied series of interbedded shale and fossiliferous limestone beds, deposited within a shallow epeiric sea, provide ideal sedimentological and paleontological context to interpret sediment geochemistry recorded at the onset of a global mass extinction. For a high-resolution section of the Kope, δ34Spyrite show an extraordinary range of variability, up to 64.5‰, with systematic oscillations throughout the core. The isotope signal represents a mix of pyrite formed at the time of deposition and during diagenesis. As sea levels fluctuated, the amount of sediment delivery influenced the connection of sediment porewaters to overlying seawater sulfate and the location of the sulfate reduction zone, which in turn, masked the primary signal. Reactive iron data suggest low oxygen concentrations in the water column, however fossil assemblages found throughout the Kope suggest otherwise. Changes in sedimentation can mask the water column signal, so these data also capture an aggregate signal. δ15Nbulk show an upsection decrease of 4.4‰, followed by a 3.4‰ increase. Though this excursion can be interpreted as a switch to increased denitrification in a low oxygen environment, the fossil record suggests the data capture localized diagenetic reactions that occur below an oxic water column. Perturbations in the ocean-climate system is often based on the interpretation of stable isotope excursions, and although excursions are diagnostic of changes to biogeochemical cycles, they may not fully account for diagenetic reactions that mask primary signals. The results from the Kope demonstrate strong localized, not global, controls on the sediment geochemistry. ItemThe Dynamics of the Late Neogene Antarctic Ice Sheets in the Central Ross Sea using a Multianalytical Approach(2022-06) Mallery, Christopher Wallace; Licht, Kathy J.; Macris, Catherine A.; Gilhooly, William P. IIIWith the goal of determining ice sheet history in the central Ross Sea since the late Miocene, the provenance of glacial till from IODP expedition 374 site U1522 was assessed using a suite of three analyses. A total of 3,869 zircons, between 250-63 microns in size, from sixteen different cores were measured for U-Pb isotopes via LA-ICP-MS. Zircon data was compared to neodymium isotope and clast lithology datasets from collaborators. Site U1522 shows three distinct provenance shifts from the late Miocene to the Pleistocene, two of which are coincident with Ross Sea Unconformities three and two. Late Miocene samples have abundant Cretaceous zircon populations, radiogenic neodymium values, and clasts interpreted as having a West Antarctic provenance. In latest Miocene samples, zircons are mostly Ross Orogeny age (c. 470 615 Ma) and Cretaceous zircon grains are almost absent, neodymium values are relatively un radiogenic, and dolerite clasts are present signaling a shift to East Antarctic derived ice. Above Ross Sea Unconformity 3, early to mid Pliocene samples show a shift back to West Antarctic provenance with abundant Cretaceous zircons and more radiogenic neodymium values. Late Pliocene to Pleistocene samples, deposited above Ross Sea Unconformity 2, reflect dominant East Antarctic provenance with few Cretaceous zircon dates, relatively un radiogenic neodymium values, and the presence of dolerite clasts. These data are broadly in agreement with ice sheet interpretations suggested by clast analysis from ANDRILL site AND-1B. Permo-Triassic zircon dates suggest the presence of unexposed bedrock of this age beneath the West Antarctic Ice Sheet based on their association with Cretaceous dates that have not been reported from East Antarctica. The zircon dataset also reveals two late Miocene intervals with a previously undocumented Eocene Oligocene magmatic event ~30 40 Ma. The coexistence of Cretaceous dates in these intervals suggests a likely West Antarctic source. The absence of Eocene Oligocene zircons in subsequent Plio Pleistocene sediments may be explained by substantial erosion and offshore deposition of the West Antarctic interior, including volcanic edifices following the Middle Miocene Climatic Transition.