Doctor of Philosophy, The Ohio State University, 2022, Earth Sciences

Climate change causes extreme precipitation patterns that result in flood and drought conditions and compromise water quantity and quality. Ireland is one of the many countries that face increasing water stress from inconsistent surface water supply and anthropogenic modification of water systems. My dissertation research generates scientific evidence to promote the development of sustainable water resource management in Ireland. The overall goal of my research is to identify the anthropogenic and natural influences on Irish river chemistry and investigate alterations to river chemistry during drought and flood conditions. Surface water samples were collected from rivers in the Shannon, Corrib, and Burrishoole catchments during the 2018 summer drought and 2020 winter flood to investigate climatic, anthropogenic, and environmental drivers of river chemistry. Stable isotopes (δ18O, δ2H, δ15N, δ34S) were used to discern [1] the impact of drought on water river resources and [2] source of nitrate (NO3-) and sulfate (SO42-) to rivers. These data were paired with [3] optical measurements of dissolved organic matter to identify characteristics and reactivity of dissolved organic carbon (DOC) and [4] concentrations of major ions, filterable iron, DOC, and nutrients to identify ‘hotspots' (elevated concentration and flux) of chemical transport. Results of δ18O–H2O and δ2H–H2O analyses show that the 2018 summer drought conditions increased surface water evaporation across Ireland, but that water stress was greatest in the location with the highest population, rather than greatest evaporative deficit. δ15N–NO3- values suggested river NO3- were derived from two primary sources: manure and soil organic nitrogen. δ34S–SO42- data suggested that river SO42- were derived from a mixture of precipitation and reduced S species. DOC pools from peatlands had lower reactivity than DOC from pasturelands. During the 2020 winter flood event, rivers in the lower Shannon catchment, with the gr (open full item for complete abstract)

Committee: Anne Carey (Advisor); William Lyons (Committee Member); Thomas Darrah (Committee Member); Franklin Schwartz (Committee Member) Subjects: Earth; Geochemistry; Hydrology

Master of Science, The Ohio State University, 2019, Earth Sciences

The Pliocene is the most recent geologic epoch that provides a strong analog for climate that is anticipated for the end of this century. The most northerly known Pliocene mummified forest in North America was discovered next to the Ad Astra ice cap, Ellesmere Island, Canada (81.7 °N) in 2009. The forest remains at this site have not been lithified, permitting high resolution geochemical and dendrochronology based analysis. Material was recovered from this site during 2009, 2010, and 2016. Stable oxygen content of ancient cellulose will allow a climate reconstruction based on transfer functions constructed from contemporary cellulose data. The deposit has been assigned a Pliocene age for these remains based on the macrofossil assemblage that is present, 14C dating, and absence of diagnostic fossils that would indicate an older age for the deposit. Alpha-cellulose from three of the recovered trees was isolated and d18O content was measured by TC/EA in tandem with IRMS. d18O of cellulose from Pliocene samples ranged from 14.19 to 17.56‰ (mean: 15.78, standard deviation: 0.89). The d18O of cellulose suggests winter average temperature of -34.7 °C (+/- 7.9), winter maximum temperature of -28.7 °C (+/- 6.4), winter minimum temperature of -40.8 °C (+/- 7.5), annual average temperature of -14.3 °C (+/- 4.9), and annual minimum temperature of -33.5 °C (+/- 7.5). Extremely low temperatures reconstructed from these specimens suggest a poor climate for tree growth and late Pliocene age. The temperature results presented here are lower than previous climate estimates for nearby Pliocene sites but are within contemporary climate constraints for a boreal forest.

Committee: Joel Barker Dr. (Advisor); Lonnie Thompson Dr. (Committee Member); Richard Dick Dr. (Committee Member) Subjects: Earth; Geochemistry; Paleoclimate Science

Master of Science (MS), Ohio University, 2015, Geological Sciences (Arts and Sciences)

The Mohave Wash fault (MWF), a low angle normal fault (~2 km of slip) initiated near the brittle-ductile transition in crystalline rocks, is associated with the regionally developed Chemehuevi detachment system. To address the role of water on initiation and early slip, δ18O of quartz/epidote pairs from thin shear zones and vein-fill were analyzed in situ using a 10 µm ion microprobe spot (precision ±0.3‰, 2 SD). 480 analyses were made on 317 grains in 23 samples collected from three vertical transects from the footwall and through the damage zone, distributed over 17 km down-dip. Quartz from undeformed hosts defines pre-faulting δ18O = 9.0–10.4‰ VSMOW. δ18O values decrease within damage zone microstructures down to -1.0‰ for quartz and -5.3‰ for epidote. Such low-δ18O values at the structurally deepest exposures are interpreted to reflect influx of surface-derived fluids to depths of > 10 km. Syn- and post-deformation mineralization in ~25% of the shear zones record heterogeneous δ18O(mineral) on the scale of < 100 mm2. Inter- and intra-crystalline variability in δ18O is greatest in the damage zone. Host clasts are often preserved, but textural relations also signify heterogeneity in new mineral growth within discrete shear zones. Of 123 grains analyzed with multiple spots, 36% are zoned in δ18O; single-grain gradients reach 8.7‰ (over 500 µm) for quartz and 2.1‰ (over 300 µm) for epidote. Differences in Δ18O(Qtz-Ep) from adjacent rims over < 100 mm2 range from 0.2–8.0‰ (in damage zone) and 0.6–2.2‰ (below damage zone). Large variability in measured Δ18O(Qtz-Ep) is consistent with variable oxygen isotope exchange, and sub mm-scale heterogeneities in permeability. Despite the intrasample-variability, overall trends in Δ18O(Qtz-Ep) from rims on adjacent grains (and thus temperature, assuming rims equilibrated) vs. vertical position are resolved. Δ18O(Qtz-Ep) generally increases (= decreasing temperature) over ~30–100 m vertical transects from the footwall into the d (open full item for complete abstract)

Committee: Craig Grimes Ph.D. (Advisor); Greg Nadon Ph.D. (Committee Member); Damian Nance Ph.D. (Committee Member) Subjects: Geology

Master of Science, Miami University, 2014, Geology and Environmental Earth Science

Modern land snail shells were collected along a north-south latitudinal gradient in North America, from 30°N to 58°N, to investigate the environmental controls on their oxygen isotopic composition (d18O) at a coarse spatial scale. The d18O shell composition is mainly a function of the d18O of precipitation, which gets lower at higher latitudes in response to lower air temperatures. Two exceptions were shells from two fens. The relatively low d18O shell composition from one fen was linked to the relatively negative d18O composition of groundwater. Calculations using a flux balance model for gastropod d18O suggest that the relatively high d18O shell composition from the highest-latitude fen might be related to low relative humidity conditions during the summer months when snails were active. LGM-dated shells were found to have higher d18O values than local modern shells. Using the model, this finding could be in part explained by a period of enhanced aridity, higher d18O values of the summer precipitation and/or the influence of 18O-enriched ocean waters, which is also suggested by other studies worldwide for some periods in the Pleistocene.

Committee: Jason Rech PhD (Committee Chair); Currie Brian PhD (Committee Member); Yanes Yurena PhD (Committee Member) Subjects: Geochemistry; Geology; Paleontology

Doctor of Philosophy, The Ohio State University, 2011, Anthropology

Major transitions in subsistence, settlement organization, and funerary architecture accompanied the rise and fall of extensive trade complexes between southeastern Arabia and major centers in Mesopotamia, Dilmun, Elam, Central Asia, and the Indus Valley throughout the third and second millennia BC. I address the nature of these transformations, particularly the movements of people accompanying traded goods across this landscape, by analyzing human and faunal dental enamel using stable strontium, oxygen, and carbon isotopes. Individuals interred in monumental communal tombs from the Umm an-Nar (2500-2000 BC) and subsequent Wadi Suq (2000-1300 BC) periods from across the Oman Peninsula were selected, and the enamel of their respective tomb members analyzed to detect (a) how the involvement of this region in burgeoning pan-Gulf exchange networks may have influenced mobility, and (b) how its inhabitants reacted during the succeeding economic collapse of the early second millennium BC. Stable strontium and oxygen ratios indicate that the Umm an-Nar inhabitants of southeastern Arabia were not highly mobile despite their increasing involvement in regional and interregional trade. However, such patterns do fit with archaeological evidence for an increasingly sedentary lifestyle associated with intensified oasis agriculture and the construction of large, permanent settlements and fortification towers. Non-local immigrants were interred in small numbers within Umm an-Nar tombs alongside local peoples, suggesting the existence of a more flexible and complex funerary ideology reflective of a broader appropriation of kinship in the formation of a multi-ethnic society. In addition, stable carbon isotope ratios suggest the consumption of a broad, mixed C3-C4 diet fitting with the employment of a variety of subsistence strategies, although preference was given to C3-based sources of food. The dramatic changes in the archaeological record associated with the transition to the Wa (open full item for complete abstract)

Committee: Clark Larsen PhD (Committee Chair); Joy McCorriston PhD (Committee Member); Sam Stout PhD (Committee Member); Paul Sciulli PhD (Committee Member) Subjects: Archaeology; Biogeochemistry; Near Eastern Studies