Master of Science (MS), Bowling Green State University, 2020, Geology

Conventional tillage, a soil preparation practice to produce a fine seedbed, can disturb the soil profile by promoting soil compaction and soil organic matter (SOM) degradation. In contrast, conservation tillage, such as no-till and minimal tillage (30% or more crop residue) have the potential to sustain or increase soil organic carbon (SOC). Additional benefits of conservation tillage include; improvement to soil structure, reducing soil erosion, greater water retention, buffering soil temperatures, and greater crop residue retention. Conservation tillage practices promote nutrient retention in soils. Furthermore; Fe- and Mn-(oxy)hydroxide minerals play an important role in SOC stabilization and sequestration, which also promotes nutrient adsorption. This study aimed to 1) quantify SOC under varying agricultural managements, 2) qualitatively describe the degree of aromaticity and recalcitrance of SOC using fluorescence spectroscopy, 3) correlate SOC quantity with nitrogen and phosphorous retention in soils, and 4) understand the mineral phases responsible for the stabilization and sequestration of SOC, as well as phosphate and nitrate using a four-step chemical sequential extraction. Results showed that no till and minimal tillage sites consistently had greater SOC and fluorescence intensity in the humic-like acids region, when compared to conventional tilled fields. The SOC quality was obtained using relatively quick and cost-effective methods. No till and minimal tillage enhanced SOC stabilization. In addition, conservation tillage practices retained the largest total nitrogen and total phosphorous concentrations at all studied depths (0-30 cm), when compared to conventional tilled fields. Sequential extraction results showed that SOC was stabilized in the following order: crystalline Fe-oxides > amorphous Fe-oxides > Mn-oxides. Fe- and Mn-(oxy)hydroxide minerals can promote the stabilization and long-term sequestration of SOC via the formation of inner sphere (open full item for complete abstract)

Committee: Angélica Vázquez-Ortega Dr. (Advisor); Andrew Gregory Dr. (Committee Member); Ganming Liu Dr. (Committee Member) Subjects: Geology

Master of Science (MS), Bowling Green State University, 2020, Geology

Annually, nearly 1.5 million tons of sediments are dredged from Lake Erie, Ohio. The main method of dredged sediment disposal is open lake disposal. Open lake disposal poses a threat to water quality by re-suspending nitrogen and phosphorus-rich sediments. The Ohio State Senate passed a bill to prohibit the practice of open water disposal after July 2020 and recommends finding alternatives uses of the dredged sediment. One alternative is to use the sediment as an amendment for farm soil. This research aimed to measure the health of soil amended with various dredged sediment ratios, determine nutrient dynamics when the soil blends were subjected to induced storm-events, and quantify the effect of dredged sediment on soybean belowground biomass and yield. We used de-watered dredged sediment from the Great Lakes Dredged Material Center for Innovation and farm soil from a legacy phosphorous (P) farm site in Oregon, Ohio. Soil analysis was conducted on the two soils for baseline data. The soils were thoroughly mixed and separated into four different soil blends; 100% farm soil, 90% farm soil to 10% dredged sediment, 80% farm soil to 20% dredged sediment, and 100% dredged sediment and placed into 32 mesocosms. Soybeans were planted in half of the mesocosms. Daily watering and five random seasonal storm events were conducted during the growing season using synthetic rainwater. After 123 days, the soybean plants were harvested, and soil cores were collected for analysis. Physico-chemical analyses were conducted on the soil, plant biomass, and percolated stormwater. Results showed that dredged sediment amendment improved the quality of the farm soil by providing additional soil organic matter, increasing the cation exchange capacity and decreased P concentration in the legacy P farm soil. Nutrient loss (phosphorous and nitrogen) in the percolated solutions showed no significant changes when compared to the percolated solutions in the 100% farm soil treatment, indicating no s (open full item for complete abstract)

Committee: Angelica Vázquez-Ortega Ph.D. (Advisor); Andrew Kear Ph.D. (Committee Member); Shannon Pelini Ph.D. (Committee Member); Anita Simic Milas Ph.D. (Committee Member); Zhaohui Xu Ph.D. (Committee Member) Subjects: Agriculture; Environmental Science; Geochemistry; Geology; Soil Sciences

PhD, University of Cincinnati, 2008, Engineering : Electrical Engineering

The objective of this research is to develop new functional nano/micro bead-packed columns on polymer lab-on-a-chips (PLOC) using self-assembly microfabrication technologies for practical on-site biochemical analyses or point-of-care clinical diagnostics. In order to achieve the goal of this research, new polymer microfabrication methods such as (a) a multi-chip assembly method for polymer chips using pin-hole pair structure and (b) a self-assembly and packing method for nano/micro beads on polymer chips have been newly developed and characterized. The novel microfabrication methods have been applied for the realization of practical polymer lab chips such as (a) sample preparation for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and (b) on-chip capillary electrochromatography with electrochemical detection for on-site clinical analysis. The state-of-art microfabrication techniques have been demonstrated by development and characterization of high quality disposable polymer capillary electrophoresis (CE) microchips. To realize polymer lab-on-a-chips in a multilayer format, a new assembly technique using pin-hole pair structure has been developed for the fabrication of multilayered polymer chips. This newly developed technique directly addresses the alignment problem that has been considered as one of the most difficult tasks in the bonding assembly of multiple polymer layers for the multi-layered polymer lab chips. Functional on-chip bead-packed columns using a slurry packing method and a self-assembly method have been developed and characterized in this work. An on-chip reversed phase chromatography (RPC) column packed with RPC media (SOURCE 15RPC) has been realized using the slurry packing method, where the geometrical restrictions with precise alignments, which are essential for the packing process, were achieved using the pin-hole pair structure assisted assembly technique. The RPC column integrated with the sample preparation chip (open full item for complete abstract)

Committee: Chong Ahn (Committee Chair); Joseph Nevin (Committee Member); Ian Papautsky (Committee Member); William Heineman (Committee Member); Patrick Limbach (Committee Member); Paul Bishop (Committee Member) Subjects: Electrical Engineering

Master of Science (MS), Ohio University, 2011, Environmental Studies (Arts and Sciences)

Productivity and soil fertility are two of the most important factors in farming. Many organic farmers fertilize their crops with composted plant or animal waste. Some organic farmers who do not have access to large amounts of compost utilize processed fertilizers that are acceptable under certified organic standards. I hypothesized that soils fertilized with composted organic matter would be more fertile and productive than soils fertilized with processed organic fertilizer. To test the hypotheses, I measured nutrient content and availability at three organic farms, each of which uses a different type of fertilizer (animal manure, composted mushroom growing medium, and processed fertilizer). I also grew beans (Phaseolus vulgaris) in soil from each of the farms to measure bean weight as an estimate of productivity. The soil amended with animal manure was the only treatment that resulted in increases in nutrients, nutrient holding capacity, and bean weight. Soils amended with processed fertilizer showed little difference from controls.

Committee: Jared DeForest (Advisor); Arthur Trese (Committee Member); Michele Morrone (Committee Member) Subjects: Agriculture; Environmental Science; Environmental Studies; Soil Sciences