Doctor of Philosophy, The Ohio State University, 2024, Earth Sciences

Atmospheric CO2 from global carbon emissions has increased at an unprecedented rate since the 1880s. Approximately 26% of atmospheric CO2 is absorbed into the surface ocean, resulting in a decrease in seawater pH referred to as ocean acidification. Additionally, increased atmospheric CO2causes the planet to warm, leading to ocean warming. Decreases in ocean pH and increases in ocean temperature negatively affect coral health, leading to decreased coral growth, cover, and biodiversity. Under future ocean acidification scenarios, the surface ocean is expected to decrease pH approximately 0.1 – 0.3 pH units, which leads to declining coral health. Calcification is energetically demanding, and when exposed to low pH corals need more fuel to maintain growth rates. Previous studies have shown a variety of responses to ocean acidification including decreased growth, decreased energy stores, or increased respiration. However, many of these effects are minimized when coral have access to food, which provides extra energy to the coral host. Most of these experiments are short or moderate-duration and do not study the long-term effects of ocean acidification to coral physiology and biogeochemistry. Therefore, volcanic CO2-vent ecosystems with naturally low pH can act as natural laboratories to study the effect of chronic ocean acidification on ecological time scales. The symbiotic coral Cladocora caespitosa and the asymbiotic coral Astroides calycularis grow at CO2-vents around the island of Ischia, Italy. To explore how these corals cope with low pH we 1) conducted a field survey of corals collected from ambient pH non-vent sites and low pH CO2-vent sites and 2) conducted a 6-month long experiment exposing corals collected from ambient and low pH sites to experimentally low pH. The field survey revealed that corals from CO2-vent sites have higher heterotrophic capacity than corals collected from ambient pH sites, allowing these corals to survive in a persistently low pH env (open full item for complete abstract)

Committee: Andréa Grottoli (Advisor); Jean-Pierre Gattuso (Committee Member); Elizabeth Griffith (Committee Member); William Lyons (Committee Member); Agustí Muñoz-Garcia (Committee Member) Subjects: Biogeochemistry; Biological Oceanography; Climate Change; Ecology; Environmental Science

MS, University of Cincinnati, 2021, Arts and Sciences: Geology

The coastal Mediterranean site of Ifri Oudadane, located in Northeast Morocco, embraces a rare and relatively continuous Holocene archeological succession capturing two main cultural periods, the Epipaleolithic (hunting-gathering) and the Neolithic (food production). The processes that led to such cultural transition in NW Africa likely involved multiple processes that are not yet fully understood. One process that has long been thought to have influenced the shift from hunting-gathering to food production is climate and environmental change. The archeological record at Ifri Oudadane is rich in well-preserved mollusk shells of the topshell Phorcus turbinatus (Gastropoda: Trocoidea) that potentially offer a wealth of cultural and environmental information over multi-centennial timescales. However, the chronology and stratigraphy of harvested shelly assemblages can be complex to interpret because they are formed by a combination of human activity and natural deposition processes. As a result, significant time-averaging, or mixing of remains that are not contemporaneous, may occur at different sections in the stratigraphy, which in turn, could lead to environmental misinterpretations. This work assesses the degree of time-averaging of harvested mollusk assemblages by directly radiocarbon dating 34 shells, using the rapid and more affordable carbonate-target radiocarbon method. Uncalibrated radiocarbon dates suggest that mollusk assemblages exhibit time-averaging between 310 to 1170 14 C years that could not be explained by analytical error alone and were not evident by stratigraphic position of the shell. These results inform the need for individually dating specimens in future paleoclimate investigations aiming for high temporal resolution. Radiocarbon results of calcitic and aragonitic mineral phases of the same shell suggest that both mineral phases appear to yield statistically equivalent ages in two out of three specimens tested. Further analyses may be necessary (open full item for complete abstract)

Committee: Yurena Yanes Ph.D. (Committee Chair); Thomas Lowell (Committee Member); Aaron Diefendorf Ph.D. (Committee Member) Subjects: Geology

Doctor of Philosophy, The Ohio State University, 2019, Food, Agricultural and Biological Engineering

Bioretention is an increasingly prevalent green infrastructure practice for urban and suburban stormwater management. While research has shown the ability of this technology to reduce stormwater volume and improve stormwater quality, there is a gap in knowledge regarding long term performance. Additionally, hydrocarbons are an important but understudied stormwater pollutant. Column studies indicate bioretention is an effective treatment technology for reducing hydrocarbons in stormwater flows, but there is limited research confirming this performance in field settings. To address both of these concerns, simultaneous studies were performed evaluating the hydrological performance and hydrocarbon removal of a bioretention cell six years post installation. Nine simulated storms (3.5 mm equivalent storm) were conducted, with eight of those sampled for hydrocarbon concentrations. Despite an apparent increase in preferential flow as indicated by rapid bromide tracer breakthrough and accelerated water table response rates, there was no significant difference in volume reduction between 2011 (average 53%) measurements and those done in this study (2015-2016: average 69%), after accounting for runoff volume differences. These results indicate continued effective operation of this facility, at least during small events. The effective operation was possibly due to location (suburban neighborhood) and maintenance (~monthly sediment removal). Hydrocarbon mass reductions in bioretention tests (83%), measured as total petroleum hydrocarbons, were similar to other studies while concentration reductions were lower (53%), possibly due to low input concentrations (0.58 mg/L). Hydrocarbon concentrations in the soil were higher in the upslope cell, indicating historical accumulations. However, within each cell, concentrations did not vary significantly over the year of study, indicating steady state conditions iv and no accumulation during the period of study. Comparisons of hydrocarb (open full item for complete abstract)

Committee: Jay Martin PhD (Advisor); Winston Ryan PhD (Committee Member); Kalcic Margaret PhD (Committee Member); Gabor Rachel PhD (Committee Member) Subjects: Biogeochemistry; Environmental Engineering; Sustainability

MS, University of Cincinnati, 2018, Arts and Sciences: Geology

Understanding the properties of time-averaging (age mixing) in a geologic stratum is essential for interpreting the paleofauna preserved in the geologic record. This work assesses the age and quantifies the scale and structure of time-averaging of land-snail-rich colluvial soils from the Deserta Islands, Madeira Archipelago (Portugal) by dating numerous individual shells using amino acid racemization (AAR) calibrated with graphite-target and carbonate-target accelerator mass spectrometry (AMS) radiocarbon methods. Snail shells were collected from seven sites on the semi-arid islands of Bugio and Deserta Grande. These islands are home to a rich indigenous malacofauna with abundant Quaternary fossils suitable for paleoenvironmental and paleoecological studies. Analyses were performed on shells of the dominant and highly abundant species Actinella nitidiuscula (Gastropoda: Hygromiidae). A radiocarbon calibration using D/L ratios of glutamic acid showed the lowest residuals relative to other amino acids and were used to estimate the ages of non-radiocarbon dated fossil snails. Results show that the fossil shells ranged in age from modern to ~48 cal ka BP, covering the last glacial and modern interglacial periods. Snail assemblages retrieved from two of these colluvial soils exhibited multi-millennialscale time-averaging, which in turn may inform time estimates of colluvial soil formation. Different age-frequency distributions between the two deposits, despite similar taphonomic conditions, suggest variability in colluvium formation is a key driver of time averaging in such deposits. This study presents the first carbonate-target AMS radiocarbon results for land snail shells and suggests that this novel method appears to offer reliable age estimates for small land snail shells for at least ~20 cal ka BP.

Committee: Yurena Yanes Ph.D. (Committee Chair); Carlton Brett Ph.D. (Committee Member); Andrew Czaja Ph.D. (Committee Member) Subjects: Geology

Master of Science, University of Toledo, 2017, Geology

Finding datable material to constrain ages of deglaciation is a key challenge faced by many Quaternary geologists. Often kettle lakes contain datable material in the form of wood and other terrestrial macrofossils within their basal sediment. These sediment units are frequently sandy layers interpreted as being deposited during downwasting as ice blocks melt within a growing kettle basin. This melting process takes time, resulting in a lag between deglaciation and the radiocarbon ages obtained from these units. Though extensively used in dating deglacial events associated with the retreat of the Laurentide Ice Sheet, little effort has been made to study this lag time and quantify its duration. This study's main objective was to characterize the depositional environment of these “basal trash layers” and determine the extent of melt-out time lags in the region previously covered by the Saginaw Lobe of the Laurentide Ice Sheet. Six lakes along the Shipshewana and Sturgis moraines in northern Indiana and southern Michigan were cored and two separate lithofacies were consistently recovered: a lower pebbly sand with variable organic content, and an upper lacustrine mud. The lower pebbly sand does not exhibit the depositional characteristics frequently described for basal trash layers. Instead, the stratigraphic, geochemical, and physical characteristics of this lower facies suggest deposition by glaciofluvial, fluvial, and/or littoral processes. Radiocarbon and optically stimulated luminescence chronology from these cores largely does not constrain the extent of melt-out time lags within these basins, aside from two lakes, where melt-out time lags of 5 ka and 7 ka are documented based on differences between basal OSL and radiocarbon ages. These OSL ages provided potential minimum ages for the Sturgis and Shipshewana moraines of 20.4 ± 1.4 ka and 23.6 ± 1.1 ka respectively, and may also provide evidence of an earlier retreat of the Saginaw Lobe than previously inferred. Fu (open full item for complete abstract)

Committee: Timothy Fisher (Committee Chair); James Martin-Hayden (Committee Member); Henry Loope (Committee Member); B. Brandon Curry (Committee Member) Subjects: Geology; Geomorphology

Master of Science, University of Toledo, 2015, Geology

Understanding the timing and rate of ice retreat in the Great Lakes Region is critical to understanding any relationship between ice lobes and climate during the Late Wisconsinan time period. The purpose of this study is to constrain the age of the Sturgis Moraine, an end moraine of the Saginaw Lobe in south-central Michigan using minimum-limiting radiocarbon and OSL ages. Previous correlations between till stratigraphy and end moraines suggest that the Sturgis Moraine formed between 15,500 and 16,100 14C yrs BP, but with little direct supporting chronologic data. To date the Sturgis Moraine, Livingstone sediment cores were collected from three scour lakes within tunnel channels at the distal side of the moraine. Scour rather than kettle lakes are chosen to minimize any organic accumulation lag from meltout of buried ice. Basal ages from gravelly sand in these cores are 13,700±60, 13,750±80, and 13,300±60 14C yrs BP. These ages are similar to basal ages from Clear Lake (13,300±300 14C yrs BP), a kettle lake on the distal side of the Valparaiso Moraine of the Lake Michigan Lobe, and the Hyre (13,690±50 14C yrs BP), Kenan (13,880±70 14C yrs BP), and Pyles (13,510±160 14C yrs BP) sites from kettle lakes on the distal side of the Fort Wayne Moraine of the Huron Erie Lobe. The minimum-limiting ages for the Sturgis Moraine presented in this study suggest a younger ice margin and smaller Saginaw re-entrant than previously envisioned. OSL dated sand dunes from within an outwash valley distal of the Saginaw Moraine (14.3±0.6 and 14.1±0.5 ka) and from dunes that migrated out of the valley bottom (12.6±0.4, 12.3±0.4, 12.4±0.5 and 12.0±0.4 ka) appear to record two separate aeolian activation periods. These ages agree with other sand dune chronologies from northwest Indiana and northwest Ohio suggesting regional variation in climate at these times. The radiocarbon and OSL ages from this study provide a best limiting minimum age of 13,750 ± 80 14C yrs BP (16,320-16, (open full item for complete abstract)

Committee: Timothy Fisher Dr. (Committee Chair); Richard Becker Dr. (Committee Member); James Martin-Hayden Dr. (Committee Member) Subjects: Geology

MS, University of Cincinnati, 2012, Arts and Sciences: Geology

Soil organic carbon affects soil fertility and agricultural production, and organic C storage can also mitigate increasing atmospheric CO2 concentrations on decadal time scales or longer. However, soil organic C storage is dependent on climatic conditions, especially temperature and precipitation, and changes in these parameters associated with climate change can act as feedback mechanisms to atmospheric CO2 concentrations. The objective of this study is to evaluate regional organic carbon abundance in northern India across orographically-limited precipitation regimes. We hypothesized that the existence of a soil organic carbon (SOC) gradient corresponding to these bioclimatic barriers, a result of this large precipitation and assumed vegetation discrepancy. Samples were collected from the Kulu Lesser Himalaya, Lahul Himalaya, and Zanskar and measured for SOC/TN inventory as well as ?14C and d13C analysis of soil organic matter (SOM). Average annual carbon accumulation and C turnover time were estimated for selected soil chronosequences, and results varied widely among the areas investigated. It was revealed that soil organic C stocks in the Indian Himalaya are sensitive to precipitation, C3 vegetation has been consistently dominant up to ~6ka B.P., and rates of accumulation and turnover are influenced greatly by variations in climate, vegetation, and topography. Examining the distribution of soil organic carbon stock can be useful in helping to predict the potential effects of warming and precipitation on C storage in this region.

Committee: Amy Townsend-Small PhD (Committee Chair); Craig Dietsch PhD (Committee Member); Lewis Owen PhD (Committee Member) Subjects: Geochemistry

MS, University of Cincinnati, 2011, Arts and Sciences: Geology

The Polar Regions are sensitive to climate change and the large ice masses located there can impact the global earth system via linkages such as sea level. Presented here is a study of a small, isolated ice mass that may be more sensitive than the Greenland Ice Sheet. Thus, here a study of the Istorvet Ice Cap is presented including a geomorphic map, radiocarbon dates from lake sediment cores as well as in-situ plant remains, and a mass balance model. Radiocarbon dates from lake sediments located in lowest elevation basin suggest this region had become deglaciated by at least 6671 yr BC (7840±80 14C yr BP: OS-86718). Additional radiocarbon dates from the same lakes shows at least a low elevation portion of the ice cap was highly restrictive relative to present for most of the Holocene. The youngest age from four similarly aged samples suggest the onset of the LIA began sometime after 737 AD (1270±80 14C yr BP: OS-86725). A mass balance model based on the PDD method suggests the average ELA over a 21-year period is 854 m a.s.l. Estimates of cumulative ice mass suggest up to 70 m of ice mass loss over the same time period. Therefore we would conclude that the Ice Cap is in a dire state. Lastly, radiocarbon dates from terrestrial in-situ plant remains from an spatial and altitudinal range suggest the Istorvet Ice Cap does not respond to the same temperature forcing as the Greenland Ice Sheet. Also, evidence is presented that suggests the Istorvet Ice Cap was expanding during the Medieval Warm Period and does not fit the traditional classification of the Little Ice Age.

Committee: Thomas Lowell PhD (Committee Chair); David Byer Nash PhD (Committee Member); Lewis Owen PhD (Committee Member) Subjects: Geology

PhD, University of Cincinnati, 2008, Arts and Sciences : Geology

The Upper Peninsula of Michigan (Upper Peninsula) has undergone several glaciations as evidenced by the presence of ice-advance moraines, extensive channels, and outwash complexes. In addition, networks of erosive valley-type depressions have been identified in the Lake Superior and Michigan basins bordering the Upper Peninsula. These features are 1-2 km wide, and are up to 200 m deep and are identified as tunnel valleys- subglacial channels found at the margin of ice sheets, thought to evacuate meltwater from the base of the glacier (Halls and West, 1971; Patterson et al., 2003; Regis et al., 2003). These valleys are hypothesized to have yielded multiple, episodic meltwater releases over time, potentially impacting deglaciation processes. To assess this, a eophysical, geomorphological/sedimentological, and chronologic examination was performed,including: 1) determining the presence of tunnel valleys across the Upper Peninsula, 2)identifying geomorphic or sedimentologic signatures of episodic meltwater releases, and 3) establishing radiocarbon chronology of ice retreat. The geophysical survey suggested the discontinuous presence of erosional valley-type features, ranging from 180 to 400 m in relief. The geomorphic investigation supported the existence of tunnel valleys on the Upper Peninsula, identifying landformsassociated with the valleys (i.e.- kettled fan outwash complexes, discontinuous eskers and channels). Episodic meltwater releases are likely, based on multiple, large-scale outwash fans, lobate kettled plains, and erosional bars. Lastly, deglaciation is thought to be time transgressive as the LIS retreated northward, based on radiocarbon dating of kettle lake organics. The LIS is suggested to have been in the Lake Superior basin by 8500 14C yr BP. These examinations indicate deglaciation in the Upper Peninsula was shaped by the presence of tunnel valleys found in the Lake Superior basin.

Committee: Thomas Lowell (Advisor); Warren Huff (Committee Member); Carrie Jennings (Committee Member); Lewis Owen (Committee Member); David Nash (Committee Member) Subjects: Geology

Doctor of Philosophy, The Ohio State University, 2009, Geological Sciences

Changes in the chemical and biological oceanography accompanying shifts in ENSO conditions in the western tropical Pacific are not well understood and this understanding would be enhanced by high resolution, century-scale proxy records spanning the euphotic zone. Soft corals and black corals are abundant in the western tropical Pacific from the near surface to thousands of meters deep, deposit organic skeleton in concentric bands, and live for hundreds to thousands of years. Geochemical measurements across colony growth axes can serve as proxies for the biogeochemistry of particulate organic matter (POM). Yet, proxy records from these corals in the climatically-sensitive western tropical Pacific have not yet been developed. Here, quantifying the natural variability in organic skeletal δ13C and δ15N values facilitated comparisons of skeletal records from multiple taxa across a depth transect within the euphotic zone. Similar δ15N values between black corals and soft corals collected from a reef offshore of Palau suggest these orders feed at the same trophic level while lower δ13C values in black corals than soft corals indicate a correction of +1.5‰ is needed to compare δ13C values between orders. In addition, due to chemical alteration of their food, suspended POM, with depth, a +0.25 ‰/10 m correction needs to be applied to δ13C values and -0.15 ‰/10 m correction needs to be applied to δ15N values to compare records from multiple depths. Stable isotopes (δ13C and δ15N) and trace elements (Br, I, Pb, Mn, Cd, Zn, and B) were measured in one Antipathes black coral colony from 5 m and two Muricella soft coral colonies from 85 m and 105 m, all collected offshore of Palau. Records were dated with a radiocarbon (14C)-derived chronology. The δ13C records decreased at rates consistent with the oceanic 13C-Suess effect, indicating anthropogenic carbon was a primary control on the δ13C of suspended POM through the top 105 m of the water. Very different δ15N records were deriv (open full item for complete abstract)

Committee: Dr. Andrea Grottoli (Advisor); Dr. Larry Krissek (Other); Dr. Matt Saltzman (Other); Dr. Larry Thompson (Other) Subjects: Geochemistry; Oceanography

Doctor of Philosophy, The Ohio State University, 2009, Soil Science

The soil organic carbon (SOC) pool is very important as a potential sink of C over human time scales. In order to evaluate the potential of soils as a long-term C sink in response to changing management and climate, it is essential to be able to experimentally partition different SOC fractions. Despite many advances in the understanding of SOC dynamics, numerous uncertainties still exist in the separation of SOC fractions with distinct stability. Therefore, the overall objective of this research was to acquire a better understanding of the stable SOC fraction in terms of pool size, structural composition, and turnover rates in two soils of the Midwestern United States (Typic Fragiudalf of Wooster, OH and Aquic Argiudoll of Monmouth, IL). Both physical and chemical fractionation methods were employed to isolate the stable from labile SOC. Comparison of the commonly used chemical oxidizing agents, namely hydrogen peroxide (H2O2), disodium peroxodisulphate (Na2S2O8), and sodium hypochlorite (NaOCl), revealed that both H2O2 and Na2S2O8 are more effective than NaOCl in isolating a stable SOC fraction enriched with alkyl-C groups and a radiocarbon age of thousands of years old. Evaluation of the physical fractions indicated that (i) sand and silt-associated SOC quickly changed with conversion from native vegetation to agricultural crops, and (ii) the clay associated SOC in agricultural soils of Wooster continues to increase, albeit at a slower rate, with increase in total SOC, while it attained maximum saturation capacity in the Mollisol at Monmouth. In general, the pool size of the stable SOC fractions isolated by physical methods was significantly higher (10.7 to 64.8% of total SOC) than that isolated by chemical methods (1.3 to 25.6% of total SOC). Combining physical and chemical methods isolated a stable SOC fraction with longer stability in the surface soils than the individual methods, while the different methods did not influence substantially the turnover rates of (open full item for complete abstract)

Committee: Rattan Lal (Advisor); Jerry Bigham (Committee Member); Peter Curtis (Committee Member); Robert Hoeft (Committee Member) Subjects: Soil Sciences

Master of Science (MS), Bowling Green State University, 2010, Geology

In northwestern Ohio, the impact of humans on natural systems extends back hundreds of years as manifested by complete reorganization of fluvial systems. This study addressed historical changes in the geomorphology the Ottawa River using vibracores, trenches, textural and geochemical analyses, and C-14 and blue light optically stimulated luminescence (blue OSL) dating. The total section thickness from trenching and vibracoring is approximately 4.5-m. The oldest sediment in the cores is interbedded massive sands and silts >1.5-m thick. These deposits represent a point bar succession that is likely post-glacial in origin. Overlying the sand is 75-cm thick interval of peats and organic-rich carbonaceous muds interbedded with thin sand horizons. Several C-14 analyses from this interval have calibrated ages of 4889 +/- 178 YBP, 4731 +/- 306 YBP, and 4547 +/- 326 YBP. These deposits are interpreted as hydromorphic paleosols and overbank flood deposits that formed following the rise of Lake Erie. An interval 33-cm to 68-cm thick overlies the paleosols and consists of alternating massive or cross-bedded sands interbedded with discontinuous silts. One blue OSL date from these sands produced an age of 231 +/- 15 YBP, which approaches the age of land clearance in northwest Ohio (early-1800s). This interval is interpreted as channel and channel margin deposits. Further up section, a cross-bedded sand layer, dated at -4 +/- 5 YBP and -9 +/- 5 YBP, corresponds with a major flood that occurred in this region during 1959. Overlying this historic flood layer are approximately 1.6-m of silty floodplain deposits that accumulated during a period of rapid population growth and construction upstream of the study area. The implications are that the Ottawa River flowed through riparian wetlands and had low banks prior to land clearance, and that excessive sediment loads dating from the agricultural period and suburbanization boom are responsible for 1.6-m of vertical floodplain aggra (open full item for complete abstract)

Committee: James Evans (Advisor); Sheila Roberts (Committee Member); Jeffrey Snyder (Committee Member) Subjects: Agriculture; Agronomy; Earth; Geology; History; Soil Sciences; Urban Planning