Master of Science, University of Akron, 2017, Geology-Environmental Geology

Lake sediment can provide records of past changes in climate, water budget and lake level, ecosystems, and human impacts to the environment. This study uses the sediment from Brady Lake, a kettle lake in northeastern Ohio, to determine Late Holocene natural and anthropogenic environmental variability. Because no bathymetric map of the lake was available, one was created in ArcMap by collecting 7,507 latitude, longitude, and water depth measurements with a Garmen 125 fathometer and GPS unit. Sediment dispersal processes were studied by collecting surface samples throughout Brady Lake. Dense, sandy sediment, having low organic content (<5%), were present in water less than 1.5 m deep where wind-wave orbital motion prevents muds from accumulating. Low density, porous muds, having high organic content (30%), accumulate below 1.5 m due to sediment focusing. A 4.13-m-long Livingston piston core was collected from the central deep-water basin to evaluate 2840 Cal yr of environmental change. Age control was determined through radiocarbon dating and correlating event stratigraphy datums to other dated Ohio kettle lake sediment records. Between 4.13 and 1.9 m core depth (2840-210 Cal yr BP), low density gyttja having 70% organic content and a C/N ratio of ~13.7 is present. These sediment characteristics are interpreted as the pre-Euro American settlement period when the watershed was forested and sediment yield was low. Within this interval, five lows in organic content, having increased sediment density, suggests a decrease in vegetation and increased watershed erosion. These changing watershed conditions may reflect fluctuations in atmospheric circulation and moisture balance during the Late Holocene. Furthermore, these lows agree with the timing of globally distributed rapid climate change occurring between 3500-2500; 1200-1000; and 600-150 Cal yr BP identified by Mayewski et al. (2004). At 1.9 m core depth, the gyttja abruptly changes to bedded mud having increased concen (open full item for complete abstract)

Committee: John Peck (Advisor); John Senko (Committee Member); Linda Barrett (Committee Member) Subjects: Environmental Geology; Environmental Science; Geochemistry; Geology; Limnology; Paleoclimate Science; Sedimentary Geology

Doctor of Philosophy (PhD), Ohio University, 2016, Civil Engineering (Engineering and Technology)

Sedimentation is one of the important factors affecting stream channel stability. The estimation of sediment supply, assessment of channel stability, and potential influencing factors are of interest in this study. A proposed model was developed by the integration of Revised Universal Soil Loss Equation (RUSLE) model and Watershed Assessment of River Stability and Sediment Supply (WARSSS), aiming to estimate the sediment load and evaluate the channel stability of a man-made channel. The proposed model was applied to the channelized Hocking River near Athens, Ohio. It was estimated that the annual gross erosion from the watershed was 728,733,738 kg, 97% of which was from the surface erosion, while only 3% resulted from streambank erosion. The total sediment yield in the channelized Hocking River was indirectly estimated by the addition of suspended sediments and bedload sediments, which were directly measured in the channel. The total annual sediment yield was 80,991,718 kg, in which 98% was estimated from suspended sediments and 2% from bedload sediments. This resulted in a sediment delivery ratio of 11%, which was consistent with those of the watersheds having similar size in the studied region. The total sediment transport capacity was estimated by the proposed model to be 17,161,761 kg/yr. Compared with the total sediment yield of 80,991,718 kg, 21% of which was transported by the river flow. The majority of sediments deposited in the channel due to the insufficient transport capacity. The amount of sediment accumulated was indirectly verified by the annual dredging project conducted by the Hocking Conservancy District (HCD). The channel stability of the Hocking River near Athens, Ohio was assessed by the characteristics of soil erosion for each monitored reach. Based on the four categories of stability determinations, most of the studied reaches were unstable in the lateral direction and all the reaches had excess deposition except one of the downstream r (open full item for complete abstract)

Committee: Tiao Chang (Advisor); Wei Lin (Committee Member); Kurt Rhoads (Committee Member); Teruhisa Masada (Committee Member); Deborah McAvoy (Committee Member) Subjects: Civil Engineering; Water Resource Management

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science (MS), Ohio University, 2024, Geological Sciences (Arts and Sciences)

Sediment transport affects how cave passages grow and behave during floods. Sediment begins moving once a critical shear stress is reached. Often, assumptions about variables affecting shear stress are necessary to model sediment transport and a variety of methods have been used to calculate shear stresses to determine when sediment transport is likely to occur. I studied sediment transport in a narrow, steep vadose passage in Fullers Cave, located in Greenbrier County, West Virginia, USA. Flow depth measurements by five in-cave probes were used with known discharges to reconstruct stream processes and sediment transport along a 95-meter reach. A sediment trap and sediment tracing were used to monitor sediment movement. To date, the largest trapped cobble had a critical shear stress of 218 N m-2, which is similar to shear stresses previously determined in the cave. Tracer rocks have been monitored twice with different sets of rocks. The mobilized tracer grains in the first experiment had a median grain size of 74mm with a maximum b axis length of 268mm. The median grain size is comparable to the 77mm median grain size obtained from Wolman counts in the affected reaches prior to the floods. The d84 grain size is being used for a second tracer rock study, but recent floods have been too small to move significant amounts of sediment. Nonetheless, floodwater velocities observed to date are between 1.5 and 1.7 m s-1 in the study reach for moderate floods and velocities during floods that moved a few rocks had maximum velocities of 0.77 and 2.1 m s-1. The critical shear stress for the largest entrained tracer rock in the second experiment was 126 N m-2, which is substantially less than shear stresses of 278-628 N m-2 generated by moderate floods recorded by an earlier study with discharges of ~1.5 m3 s-1. The results indicate that the cave is capable of transporting larger grains than are currently found in the study reach, which is consistent with intermittent exposures (open full item for complete abstract)

Committee: Gregory Springer (Advisor); Daniel Che (Committee Member); Eung Seok Lee (Committee Member) Subjects: Geological; Geology; Geomorphology

Master of Science, University of Akron, 2023, Geology

In 1967, Wolman modeled how human land-use modification affects sediment yield in the U.S. Middle-Atlantic. This study uses the sediment of Wyoga Lake, Summit County, Ohio to quantify the impacts of land use change on sediment yield, to determine if there is a relationship between land use and the sedimentary heavy metal record, and to test if Wolman's model is applicable to northeast Ohio. Mud Brook flows into and out of Wyoga Lake, thus the lake traps much of the sediment yield from the upper Mud Brook watershed. Based upon wave base models and lakefloor sediment properties, lacustrine sediment accumulates in water deeper than 2.8 m. Sediment cores were collected from deep-water basins and dated by correlating to absolute-dated cores from other Ohio kettle lakes and by using event chrono-stratigraphy to identify lithologic features associated with events of known age. The 266.5 cm-long composite core contains a 220-year environmental history record that was divided into 5 periods of varying human-induced land use change to the Wyoga Lake watershed. The oldest Period, the Pre-Settlement Period (pre-1804) extends from 266.5 to 240.5 cm below lake floor (cmblf) and has organic-rich mud, low Ti concentrations, and a low mass accumulation rate (MAR) of 0.026 g/cm2/yr that accumulated when the forested watershed limited sediment yield. The Settlement and Agriculture Period (240.5─147.6 cmblf; 1804─1964) begins with an initial decline in organic matter followed by elevated arsenic concentrations later in the Period, and a MAR of 0.323 g/cm2/yr which is 12X greater than the Pre─Settlement Period. The sediment properties are interpreted to represent increased terrigenous influx due to deforestation when Stow and Hudson, OH were settled, followed by agricultural activities that applied arsenic-based insecticides to orchards. The Lakeside Housing and Construction Period (147.6 to 94.0 cmblf; 1964─1984) occurred prior to the use of construction-site erosion control practices (open full item for complete abstract)

Committee: John Peck (Advisor); John Senko (Committee Member); Caleb Holyoke (Committee Member) Subjects: Geology; Limnology

Master of Science in Environmental Science, Youngstown State University, 2021, Department of Physics, Astronomy, Geology and Environmental Sciences

Suspended sediment impacts the water quality of streams and rivers by retaining and acting as a carrier for other contaminants, increasing turbidity, which can block light from getting to submerged vegetation and clog fish gills, amongst other environmental effects. Therefore, understanding its dynamics and prediction is crucial to environmental protection and water management. The objective of this study is to improve the prediction accuracy of suspended sediment load in rivers and streams by grouping monthly data of suspended sediment and water discharge into groups of similar precipitation values. Linear regression was used to predict the suspended sediment load, a dependent variable, as a function of the stream water discharge, an independent variable on four U.S. rivers and streams. This study used ten years of data for the suspended sediment load, stream water discharge, and precipitation for each river. Results from the traditional approach, which does not have precipitation data and is therefore ungrouped, were compared with results from the precipitation approach using the correlation coefficient (r) and the percent deviation. Out of the 21 groups investigated, 19 groups showed a lower percent deviation from the traditional approach. For the correlation coefficient values, 12 groups were higher than the traditional approach, while two groups had the same values as the traditional approach. Ten groups had correlation coefficient values between 0.90 to 0.97. Overall, the precipitation approach has improved the prediction accuracy of the suspended sediment load compared to the traditional approach.

Committee: Isam E. Amin PhD (Advisor); Alan M. Jacobs PhD (Committee Member); Douglas M. Price PhD (Committee Member); Wes Vins MS (Committee Member) Subjects: Environmental Science

Master of Science, University of Toledo, 2021, Biology (Ecology)

Chapter 2: Stratification and hypoxia in the western basin of Lake Erie (WBLE) has been shown to result in phosphorus flux from the underlying sediment, which could provide necessary nutrients for harmful algal bloom (HAB) growth. Studying the duration and frequency of hypoxic events would provide pivotal information for estimations of phosphorus flux from underlying sediments. However, due to the ephemeral nature of hypoxic events in the WBLE, planned weekly vessel-based sampling trips are inadequate for alerting researchers of the onset of hypoxia, making sampling such events difficult. Instead, water quality instruments can be deployed to collect and relay live data to researchers in a much more frequent timeline. In this study, a buoy equipped with a thermistor string and an EXO3 sonde (Yellow Springs Institute) was deployed to monitor for potential stratification and depleting lake bottom oxygen concentrations. This system measured water quality parameters and posted the data online every 20 minutes. Using these data, immediate vessel-based sampling trips to 7 sites were made according to observed hypoxia. Data captured show a hypoxic event occurred in the WBLE during early July 2020 that persisted for several days before being mixed by a storm on July 11, 2020. This hypoxic event coincided with 8 days of stratification. In addition, hypolimnion water warmed to over 23 ℃ while remaining stratified from the overlying waters, which could facilitate higher phosphorus flux from sediments. On average, phosphorus concentrations in the hypolimnion were 1.06 µ/L (~43%) higher than in the epilimnion by the end of the event, suggesting that sediments were releasing phosphorus into the overlying waters. Chapter 3: The western basin of Lake Erie (WBLE) has been experiencing Harmful Algal Blooms (HABs) for over a decade. These blooms have been detrimental to the health of Lake Erie and the safety of drinking water for surrounding communities. Nutrient inputs (namel (open full item for complete abstract)

Committee: Thomas Bridgeman Dr. (Committee Chair); Michael Weintraub Dr. (Committee Member); William Hintz Dr. (Committee Member) Subjects: Ecology; Environmental Science; Limnology

Master of Science (MS), Wright State University, 2018, Earth and Environmental Sciences

The western basin of Lake Erie experiences annual non-nitrogen (N) fixing harmful algal blooms (HABs), while the central basin experiences seasonal hypoxia in bottom water. In the western basin, water column oxygen respiration rates were quantified at four stations throughout the 2016 and 2017 field seasons, including the proportions of total oxygen consumption accounted for by sediments and by water column nitrification (measured in parallel; Hoffman, unpublished data). Water column respiration rates in the central basin of Lake Erie also were measured in July 2017 during seasonal bottom-water hypoxia. Volumetric water column respiration in the western basin in 2017 (0.011–1.227 mol O2/L/hr) was significantly lower than in 2016 (0.275–1.859 mol O2/L/hr; ANOVA, p < 0.001). In July 2017, western basin respiration rates (0.524 ± 0.124 mol O2/L/hr) were not significantly different from those measured on the same day throughout the central basin water column (0.428 ± 0.089 mol O2/L/hr). Lower rates of water column respiration and sediment oxygen demand (SOD), measured in parallel (Boedecker, 2018), in 2017 coincided with a larger contribution of cyanobacteria to the phytoplankton community relative to 2016. The contribution of nitrification to water column oxygen consumption in the western basin was significantly lower than reported in a previous study. Microbially-mediated transformations occurring in aquatic sediments contribute to in situ N concentrations and availability for primary producers, including cyanobacterial HAB organisms performing photosynthesis. Sediment subsamples were collected in the western basin of Lake Erie in 2016 and 2017, and DNA was extracted to quantify functional gene copies as a proxy for the abundance of microbes capable of denitrification (nirS), N fixation (nifH), and dissimilatory nitrate reduction to ammonium (DNRA; nrfA). The gene copy abundance of nirS was significantly correlated (p = 0.002) with denitrification rates measured i (open full item for complete abstract)

Committee: Silvia Newell Ph.D. (Advisor); Mark McCarthy Ph.D. (Committee Member); Chad Hammerschmidt Ph.D. (Committee Member) Subjects: Biogeochemistry

Master of Science (MS), Bowling Green State University, 2017, Geology

Suspended sediment in water bodies is a considerable environmental concern. Traditional sampling methods for suspended sediment are time-consuming as they involve vertical and spatial point-sampling. Remote sensing (RS) is an alternative to in-situ measurements and it is capable of monitoring suspended sediments in shallow waters spatially at large scales. Use of RS technology to map suspended sediment concentrations (SSC) depends on sensor type and its capability `to see through' the water column at given surface and water column conditions. This study examined the capabilities of RS technology to spatially quantify SSC at multi-depth intervals within the Maumee River, Ohio. Water samples were collected and analyzed for SSC in May, June, and October at depths of 0.5 ft., 2 ft., 3 ft., and 6 ft. Landsat 8, surface hyperspectral measurements (aggregated to simulate sensors), and MicaSense Sequoia camera onboard an unmanned aerial vehicle (UAV) were used. Single spectral bands, ratios, and multiple bands/ratios were examined in developing algorithms relating RS and field measurements. Linear regression models provided the best relationship for surface, Landsat 8, and UAV data throughout all depths. A 6 ft. depth had the highest correlation for surface (R2adj=0.93) and Landsat 8 (R2adj=0.79) data. For UAV a 3 ft. depth provided the best relationship (R2adj=0.52). Band ratios using nonlinear fitting provided good relationships (surface R2adj=0.72 and Landsat 8 R2adj=0.54) at 6 ft. as well. Results showed Landsat 8 more accurately measured suspended solids at 6 ft. than shallower depths. Regression equations and band ratios showed increasing relationships with SSC with increasing depth for Landsat 8 with an exception for 3 ft., which can occur due to stratification. UAV measurements produced best results for 3 ft. Algorithms with best results included ultra blue, blue, and green bands which are not typically used for quantifying SSC. Shorter wavelength bands (400 nm-5 (open full item for complete abstract)

Committee: Anita Simic (Advisor); Robert Vincent (Committee Member); James Evans (Committee Member) Subjects: Geological; Geology; Geotechnology; Hydrology; Remote Sensing; Sedimentary Geology

Master of Science in Environmental Science, Youngstown State University, 2015, Department of Physics, Astronomy, Geology and Environmental Sciences

Sediment is the number one pollutant in the United States. Sediment in streams and rivers also carries along other pollutants such as nutrients (phosphorus and nitrates) and harmful bacteria. This study employs linear regression to predict the suspended sediment load, a dependent variable, as a function of the stream water discharge, an independent variable in seven U.S. Rivers and streams. The major objectives of the study are to investigate the effect of the sediment record length on the accuracy of the prediction, and to investigate the correlation of the suspended sediment load with nutrients and fecal coliform. The linear regression results showed that sediment sources/sinks and hydrologic variations that take place throughout the year play a vital role in the regression analysis of suspended sediment data. Five of the seven investigated rivers produced accurate predictions of the suspended sediment load. The sediment record length can affect the value of the correlation coefficient between the streamflow and suspended sediment rate. The percent deviation between the predicted and suspended sediment is less likely affected by the sediment record length and most likely affected by the hydrologic variations and sediment sources/sinks. Two of the investigated rivers show that significant hydrologic variations and sediment sources/sinks can increase the percent deviation, regardless of the sediment record length. This study also includes a Pearson correlation between the suspended sediment load, nutrients and fecal coliform. The Pearson correlation results showed no correlation between the suspended sediment loads and nutrients but high correlation was seen between the fecal coliform and the suspended sediment loads in the investigated rivers. The two investigated rivers for Pearson correlation are influenced by flow, which greatly determines the other parameters, even though the two rivers have different physical conditions.

Committee: Isam Amin PhD (Advisor); Alan Jacobs PhD (Committee Member); Carl Johnston PhD (Committee Member); Lawrence Gurlea (Committee Member); Gloria Johnston PhD (Committee Member) Subjects: Biology; Environmental Science; Geology; Statistics

Master of Science, University of Akron, 2015, Geology

The sediment in Rex Lake, a kettle lake in Northeast Ohio, preserves a record of modern sedimentation processes and past anthropogenic impacts to the lake and its watershed. Rex Lake is connected to a series of kettle lakes and human-made reservoirs that forms the Portage Lakes System, a popular recreational area. Rex Lake is affected by sediment focusing processes and has a wave base of 2 m. Sands and gravels having high dry bulk density and low organic content are present in water less than 2 m deep. Organic mud and calcareous mud are present in water depths greater than 2 m. The acoustic properties of the lakefloor were used to remotely determine differences between sands/gravels and muds. Because of differences in matrix lithology and pore geometry of the organic muds and calcareous muds, this study shows that caution must be exercised when using acoustics to remotely sense lakefloor sediment grain size. The upper 4 m of mud, from the middle of the lake, was cored and measured for physical properties, sedimentology and trace metal content. Four time periods having distinct sediment characteristics were identified and related to changing anthropogenic activities. The Pre-settlement Period characterizes organic mud below 135 cm core depth, having low sediment density, magnetic, and trace metal content. This sediment is inferred to have accumulated while the watershed was forested prior to Euro-American settlement of the area in 1805. In the Settlement Period, between 135 and 70 cm core depth, organic content decreases, magnetic content and sediment density increase slightly, and trace metal content remains low. These sediment changes are inferred to reflect increased erosion as the watershed was deforested for agricultural activities. In the Recreation Period, between 70 and 20 cm core depth, organic content decreases to its minimum value whereas the trace metal, magnetic content, and sediment density increase greatly. During this period increa (open full item for complete abstract)

Committee: John Peck Dr. (Advisor); David Steer Dr. (Committee Member); James McManus Dr. (Committee Member) Subjects: Environmental Geology; Geology; Geophysics; History

Master of Science (MS), Wright State University, 2013, Earth and Environmental Sciences

Trace metals in the ocean are derived from natural and anthropogenic sources. Despite increased human impact on the marine environment and biological productivity of continental margins, trace metal studies in marine sediments have focused primarily on near-shore regions. I investigated 22 metals in sediments on the continental margin of the northwest Atlantic Ocean to calculate enrichment factors (EF) relative to upper continental crust and identify spatial variations with distance from shore and depth below the sediment-seawater interface. Metals were well correlated with Al, Fe, organic matter, or CaCO3. No clear trends in metal EFs with distance from shore were evident on a station by station basis, but consistent differences among regions of the continental margin were evident. Significant near-shore enrichment was observed. Enrichment was also evident for As, Hg, Mn, and Ni in sediments farther off-shore, suggesting the influence of human activities or hydrothermal vent emissions have enriched deep ocean sediments.

Committee: Chad Hammerschmidt Ph.D. (Advisor); Chad Hammerschmidt Ph.D. (Committee Chair); Carl Lamborg Ph.D. (Committee Member); William Fitzgerald Ph.D. (Committee Member) Subjects: Chemical Oceanography; Environmental Science; Oceanography

Master of Science (MS), Wright State University, 2007, Earth and Environmental Sciences

Porosity and permeability are parameters that affect the flow of ground water in the subsurface and have significant implications on the modeling of fate and transport of contaminants. However, little has been done to quantitatively examine the effect on porosity and permeability of packing in bimodal mixtures of natural sediment. This study compares measurements of porosity and permeability on model bimodal sediment mixtures with predictions from petrophysical models. The main goal is to evaluate how well these petrophysical models predict porosity and permeability in bimodal mixtures of natural sediment. The effect of the volume fraction of fines on porosity and permeability within bimodal sediment mixtures using natural grain size components will also be examined. First, I took measurements on the mixtures to determine porosity values. Then I compared these values to those predicted by the expanded fractional packing model for porosity. The expanded fractional packing model for porosity represents mixtures in which finer grains approach the size of the voids among the pre-mixed coarser grains. Next, I utilized a grain size statistical method to derive estimates for permeability, using the measured porosity values. I then compared these estimates to measured permeability values. I took permeability measurements on the mixtures using air- and water-based methods. Finally, I made conclusions about the petrophysical models for porosity and permeability to determine whether or not they were applicable to natural sediment. These conclusions will help to improve the confidence in estimating the parameters of porosity and permeability.

Committee: David Dominic (Advisor) Subjects: Geology; Hydrology

Master of Science, University of Toledo, 2010, Civil Engineering

The objective of this research was to determine the potential for sediment contribution to Microcystis bloom formation in the Western Lake Erie Basin during summer 2009. It was hypothesized that Microcystis will overwinter in sediments and may be transported, along with phosphorus, to the water column when environmental conditions support algal bloom formation. Before, during, and after the Microcystis algal bloom, surface water and sediment samples were collected and analyzed from six fixed locations in the Western Lake Erie Basin. Detectable Microcystis concentrations were present in the sediment during and after the bloom at all six sites ranging from 5.5x104 to 2x105 cells per gram of dry sediment. This corresponded with the appearance of detectable Microcystis concentration in the lake during and after the bloom at five of the six sites ranging from 5x103 to 7x104 cells per milliliter across the entire water column. However, phosphorus concentrations in the sediment could not be correlated with any significance to the Microcystis cell density in the lake during or after the bloom. These findings suggest that Microcystis colonies do deposit into Lake Erie sediments and that these colonies may remain at some sediment sites until bloom formation the following summer.

Committee: Dr. Cyndee Gruden (Advisor); Dr. Andrew Heydinger (Committee Member); Dr. Defne Apul (Committee Member); Dr. Cyndee Gruden (Committee Chair) Subjects: Environmental Science

Master of Science (MS), Ohio University, 2012, Civil Engineering (Engineering and Technology)

The purpose of this thesis was to investigate the sediment transport capacity of the Hocking River in the 9-km long channelized reach between White's Mill and the State Route 50 Bridge, located on the eastern side of Athens, Ohio. Sediment transport capacity was determined using Hydrologic Engineering Centers River Analysis System (HEC-RAS) 4.1 and was compared to inflowing sediment rates to determine overall channel efficiency. Sediment transport efficiency as well as RUSLE sediment delivery ratio analysis indicate the channel has insufficient sediment transport capacity during average and below average flow conditions. Approximately, 1/8th of the channel has efficient sediment transport capacity during flood conditions. The threshold sediment delivery rate that would allow for sufficient transport was determined for the average flow and 1998 flood condition, based on erosion potential estimated by the Revised Universal Soil Loss Equation. Threshold sediment delivery rates indicate that sediment accumulates during average or low flow conditions, when the channel has insufficient sediment transport capacity. A fraction of the accumulated sediment is then removed during flood events, when the channel has more than sufficient capacity.

Committee: Tiao Chang PhD (Advisor); Gregory Springer PhD (Committee Member); Deborah McAvoy PhD (Committee Member); Guy Riefler PhD (Committee Member) Subjects: Civil Engineering

Master of Science, University of Akron, 2010, Geology

The trend of dam removal in the United States to improve water quality has caught the interest of the City of Cuyahoga Falls in removing the 4.1-m tall LaFever Dam from the Cuyahoga River. Upstream of the LaFever Dam, the neighboring city of Munroe Falls, successfully removed the Munroe Falls Dam in 2005 which improved water quality and drew more people to the water-front. Before a dam is removed various studies must be conducted on the river environment, both upstream and downstream of the dam. This two-year study documented continued lateral erosion and coarsening of channel-floor sediment upstream of the former Munroe Falls Dam. Cross-sectional profiles downstream of the former Munroe Falls Dam have recorded both aggradation and degradation, as the sediment released from the former Munroe Falls dam pool is transported downstream towards the LaFever dam pool. Currently sand is deposited downstream of Water Works Park as a deltaic feature. The LaFever Dam has decreased river slope, flow velocity and boundary shear stress, thus favoring fine-grained sediment deposition within the dam pool. Within the LaFever dam pool, approximately 52,000 m3 or 35,000,000 kg of sediment has accumulated. The amount of trace-metal contaminants in the sediment was measured to assess potential impacts the possible removal of the LaFever Dam will have on the down-stream environment. LaFever dam pool sediment has concentrations of Pb, Cr and Zn above the ERM values (218, 370 and 410 ppm) which may cause adverse biologic effects. Therefore, additional studies including those of organic pollutants are needed before the LaFever Dam is removed.

Committee: John Peck Dr. (Advisor) Subjects: Environmental Science; Geochemistry; Geology

Master of Science, The Ohio State University, 2024, Earth Sciences

The health of Caribbean coral reef ecosystems has declined rapidly in recent decades due to climate change and local human stressors. Although there are robust data sets following the onset of large-scale monitoring in the late-1970s, less is known about reef health before this time. Furthermore, most of this monitoring work has focused on such organisms as corals, parrotfish, and echinoderms; much less is known about how changing environments are reflected in other important coral reef community members (e.g., molluscs). Reef matrix cores can help fill this knowledge gap, as they provide records of reef communities and environments over the past centuries to millennia, prior to large-scale human disturbance. To obtain a more accurate baseline of reef ecosystem structure and functioning and to track ecosystem change over the past one and a half millennia, I assessed changes in the taxonomic and functional group composition of subfossil assemblages of bivalves, gastropods, corals, and urchins preserved in 3.5 m-long cores from three reefs within the central lagoon of Belize. Bivalve and gastropod composition was assessed using relative abundance of shells, whereas urchin and coral composition was assessed using the accumulation rate of spines and coral fragments measured by weight. These cores record a shift in the dominant substrate relationship in bivalves from epifaunal to infaunal over time, which becomes most prominent in the late-1800s, indicating a loss of hard substrate (i.e., corals). Additionally, this epifaunal decline coincides with an increase in soft-substrate-indicating gastropods (e.g., Cerithium spp.) and the gorgonian coral associated bivalve Dendostrea spp. In contrast, urchin composition shows little change through the equivalent time interval, with the currently common Echinometra spp. dominating throughout the cores. These trends mirror those that have been observed previously from reef matrix cores in Caribbean Panama, as well as Belizean verte (open full item for complete abstract)

Committee: Jill Leonard-Pingel (Advisor); Loren Babcock (Committee Member); Andréa Grottoli (Committee Member) Subjects: Geological; Paleoecology; Paleontology

Master of Science in Engineering, Youngstown State University, 2024, Department of Civil/Environmental and Chemical Engineering

The 108-mile-long Mahoning River, historically one of the most contaminated rivers in the U.S., contains metals above the EPA aquatic criteria. This study identifies the contamination levels, spatiotemporal patterns, sources, speciation, and bioaccessibility of metals (As, Ba, Fe, Pb, Ni, Zn) in the water and sediment of the lower Mahoning River. Sediment analysis showed that all metals exceeded the Sediment Reference Value, except for Ba. Regression analysis showed a significant decrease of Pb and Fe (p < 0.05) in water from 1993-2021, suggests that the water quality of the river with respect to Pb and Fe is improving comparatively in the past three decades. The contamination factor indicated that metals in water were uncontaminated (< 1), while metals in sediment were moderately to highly polluted (3-15). Inverse distance weighting in sediments illustrated decreasing concentrations towards downstream for Ni, while increasing concentrations towards downstream for As, Ba, Fe, Pb, and Zn in sediment. The inverse distance weighting patterns may be associated with land use, as the river traversed the agricultural region upstream, the urbanized region downstream, and mixed-land areas in the last stretch. Speciation analysis revealed metals in water and sediments were in divalent forms (HM2+), except Pb (PbOH+, PbCO3), indicating high bioaccessibility and potential plant uptake in the aquatic environment.

Committee: Sahar Ehsani PhD (Advisor); Felicia Armstrong PhD (Committee Member); Rick Deschenes PhD (Committee Member); Bradley Shellito PhD (Committee Member) Subjects: Environmental Education; Environmental Engineering; Environmental Geology; Environmental Science; Environmental Studies; Geographic Information Science

Master of Science (MS), Ohio University, 2024, Geological Sciences

This study investigates the extent, nature, and formation processes of Paleo Lake Buckeye during the Late Pleistocene, located in the Buckeye Creek watershed in the central Appalachian Mountains. This thesis integrates GIS mapping, field methods utilizing sediment coring and trenching, radiocarbon dating and grain size analysis to reconstruct the margins and depositional environments of Paleo Lake Buckeye and its surrounding landscape. Radiocarbon and optically stimulated luminescence (OSL) dating indicate that the lake formed between 20,000 and 40,000 years ago, coinciding with the peak of the last glacial epoch. The stratigraphic analysis shows fine-grained lacustrine deposits, organic rich layers, and episodic coarse-grained beds, which reflects periods of quiet water deposition interrupted by high-energy events. Paleo Lake Buckeye's formation is linked to periglacial conditions, where freeze thaw cycles mobilized sediments and permafrost dynamics influenced hydrological processes. This research not only interpret the paleoenvironmental conditions of the Buckeye Creek watershed during the Late Pleistocene, but also contributes to broader discussions on glacial and periglacial processes, climate variability, and landscape evolution in the central Appalachian Mountains.

Committee: Gregory Springer (Advisor); Katherine Fornash (Committee Member); Eva Lyon (Committee Member) Subjects: Environmental Geology; Environmental Science; Geochemistry; Geographic Information Science; Geography; Geological; Geology; Geomorphology; Paleoecology; Paleontology

Master of Science, The Ohio State University, 2024, Evolution, Ecology and Organismal Biology

Eutrophication of freshwater ecosystems is a global environmental problem often caused by excess bioavailable phosphorus (P). Thus, it is important to understand the sources and sinks of bioavailable P in a watershed. Previous work suggests that during high flow events, which dominate annual P and sediment loads, exchange of P between dissolved and particulate forms impacts the bioavailability of P exports to recipient ecosystems. Yet, suspended sediment is derived from many sources on the landscape, which can differ in chemical composition and likely, affinity for P sorption. Human activities can impact sediment source so, it is important to understand the connection of composition to sediment source, and how source influences sediment-P (sedP)-dissolved reactive P (DRP) interactions during high flow. To address this, I collected seven distinct sources (four streambank soils, two cropland soils, and streambed sediment) from a Maumee River tributary; the Maumee watershed is the main source of P fueling Lake Erie cyanobacteria blooms. Using source material collected in May, June, and December, I conducted three experiments which examined sedP-DRP interactions in a simulated high flow environment for 120 hours. I also measured aspects of sediment composition including size, P content, and P saturation (Mehlich-III P:Mehlich-III Fe). Cropland, streambank, and streambed sources were distinct in chemical composition and P sorption rate capacity; streambed and streambank sources had low P saturation and high P sorption during the first day of the experiment. In contrast, cropland sources had high P saturation and low P sorption. My results indicate that sediment source influences sedP-DRP interactions during high flow events, suggesting that changes in land management that alter the relative balances of sediment sources, or P saturation, may influence in stream P transformations and bioavailability of P exports to recipient ecosystems.

Committee: James Hood (Advisor); John Lenhart (Committee Member); Casey Pennock (Committee Member); Tanja Williamson (Committee Member) Subjects: Aquatic Sciences; Ecology; Geochemistry