Doctor of Philosophy (PhD), Wright State University, 2023, Environmental Sciences PhD

Successful crop production relies on soils with balanced physical, chemical and biological properties. Demand for greater crop yields has led to the breakdown of soil properties through detrimental agricultural practices. To combat soil degradation, farmers employ field management practices including cover crop application, crop rotation strategies and organic soil amendment addition. These practices, used independently or in combination, can improve soil stability, increase soil nutrient content and functions of beneficial soil microbiota while increasing crop yield. Despite showing promise as an organic soil amendment, dredged sediments are still not well understood, due in part to the fresh or weathered conditions dredged sediments can be applied. Specifically, there is currently no research combining dredged sediments with cover crops, comparing different dredged sediments conditions in a single study or evaluating dredged sediment condition coupled with cropping strategies. To address these knowledge gaps, my dissertation evaluates changes in soil properties and crop responses when dredged sediments are coupled with these practices. I evaluated changes in dredged sediment property responses and corn production following winter rye cover crop application compared to a fallow season in a field experiment where I found cover crop application increased corn yields compared to a fallow season. These differences were driven by microbial-associated nutrient mineralization. Additionally, I quantified soil property and corn responses to different application ratios of fresh and weathered dredged sediments in a greenhouse experiment and determined applications of dredged sediments calculated based on the nutrient recovery ratio are not sufficient to provide benefits to agricultural soils. However, in 100% applications, weathered dredged sediments were more beneficial to corn growth than agricultural soils, while fresh dredged sediments proved detrimental to corn growth. (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2022, Environmental Science

Accelerated erosion-induced topsoil loss threatens the productivity and sustainability of maize (Zea mays L.) cropping systems across the U.S. Corn Belt by adversely impacting soil health. The rehabilitation of soil health in eroded topsoil has been shown to improve with best management practices coupled with soil amendment application. The current study investigated the impact of simulated erosion and annual amendment application on soil health 20 years after establishment at two central Ohio sites (Waterman Farm: WF; Western Station: WS). Simulated erosion was employed in 1997 to create three incremental topsoil depths (TSD) (20 cm topsoil removed (TSD-0); 0 topsoil removed (TSD-1); 20 cm topsoil added (TSD-2). Annual application of three soil amendments (inorganic, synthetic N fertilizer (I); organic, compost manure amendment (O); no amendment (C)) were investigated for their ability to restore soil health in the surface 40 cm of these cropping systems. Increasing TSD resulted in more favorable physical, chemical, and biological soil health attributes primarily through enhanced soil structure, aggregation, water movement and storage, soil pH range, and SOC and soil N concentrations. The organic amendment proved most efficient in regenerating soil health at lower TSD levels and augmenting soil health in systems with greater TSD levels. Greater TSD usually resulted in greater C and N pools after two decades. However, this was variable at levels where greater TSD was present. Soils amended with the organic treatment always produced greater C and N stocks across both sites. The trends in SOC pools were TSD-1 ≥ TSD-2 > TSD-0 at the WF site and TSD-2 ≥ TSD-0 ≥ TSD-1 at the WS site. The trend in TN pools followed the same pattern as SOC pools at the WF site, but was TSD-2 ≥ TSD-1 ≥ TSD-0 at the WS site. Soils with greater TSD and those amended with the organic amendment were more resilient in the face of simulated rainfall and resulted in the smallest incurred losses of (open full item for complete abstract)

Master of Science, The Ohio State University, 2018, Environment and Natural Resources

Maize (Zea mays L.) is the principal food source for Eastern Africa's rising populations. In Morogoro Region, Tanzania, 56% of agricultural land is cropped with maize and 90% of its people are smallholder farmers. For these reasons, understanding the relationship between crop management decisions, agricultural soil quality, and maize yield is of critical importance. Field management practices were recorded during the November – January (short) rainy season crop, and the March – June (long) rainy season, and water use during the short rainy season. Soil samples were taken from each field in June 2017 and analyzed for soil quality parameters pH, total nitrogen (TN), soil organic carbon (SOC), bulk density (BD), texture, aggregate stability (AS), and penetration resistance. Analyses indicated that during both the short and long rainy seasons, maize production resulted in a lower pH than in vegetable production, or maize – cowpea intercrop. Fields which were cropped with maize in the long rainy season had higher clay content (Clay) than did those cropped with a maize – cowpea intercrop. Sand content (Sand) appeared to be higher in fields cropped with a maize – cowpea intercrop in maize in the long rainy season. Textural variation was accounted for a spatial gradient in soil series, which likely informed crop choice. Aggregate stability was found to be higher in fields cropped with maize in the short rainy season than with vegetable. TN, SOC, BD, silt content (Silt), and penetration resistance were not found to vary between iii crop management practice. Each soil quality parameter was entered into a linear regression model and a mixed effects model with long rainy season maize yields to determine the property's association with maize production. These analyses indicated that BD and sand concentration were negatively affecting maize yields while silt concentration, and to a lesser extent, SOC and AS were positiv (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2011, Environmental Science

In an attempt to slow the increase in atmospheric CO2 enrichment, researchers are looking at the capacity of world soils to sequester carbon (C) and mitigate global climate change (GCC). Analyses of U.S. turfgrass soils throughout diverse ecoregions indicated that home lawns sequester soil organic carbon (SOC). Rates of SOC sequestration to 15 cm depth ranged from 0.01% yr-1 to 0.70% yr-1 with the majority of lawns sequestering SOC to concentrations of 2-3%. Notably high SOC concentrations were observed in Minneapolis, MN (5.6%), Wooster, OH (3.4%), Denver, CO (3.2%), and Duluth, MN (3.1). In contrast, notably low concentrations were observed for soils located in Atlanta, GA (1.5%). Differences in SOC concentration and pool were attributed to differences in climatic and soil properties across ecoregions. The mean annual temperature (MAT) was negatively correlated with SOC concentration and pool, while both mean annual precipitation (MAP) and soil bulk density (ρb) indicated a nonlinear interaction with optimal SOC concentrations at MAP of 60-70 cm yr-1 and ρb of 1.4-1.5 Mg m-3. Additionally, soil nitrogen (N) concentration was positively correlated with both SOC concentration and pool. Rates of SOC sequestration ranged from 0.9 Mg C ha-1 yr-1 to 5.4 Mg C ha-1 yr-1, with a national average of 2.8 ± 0.3 Mg C ha-1 yr-1. Differences in rates of SOC sequestration were also attributed to differences in MAP, soil N concentrations, and ρb, however, SOC sequestration rate was also positively correlated with fine soil texture content and pH. The potential C sink capacity of soils was determined and ranged from 20.8 ± 1.0 Mg C ha-1 in Portland, ME to 96.3 ± 6.0 Mg C ha-1 in Minneapolis, MN, with an average across ecoregions of 45.8 ± 3.5 Mg C ha-1. The hidden carbon costs (HCC) of home lawn maintenance due to fertilizer use (0.06 Mg Ce ha-1 yr-1) and mowing fuel combustion (0.19 Mg Ce ha-1 yr-1) produced a mean total emission across sites of 0.25 Mg Ce ha-1 yr-1. Accounting fo (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2022, Horticulture and Crop Science

Many Midwestern organic farmers in their focus on improving soil quality for crop production attempt to balance their soil's calcium (Ca) and magnesium (Mg) saturation levels by applying calcium-rich amendments. For most soils, this practice based on the base cation saturation ratio (BCSR) hypothesis, requires repeated applications of calcitic limestone and or gypsum to increase Ca to approximately 65% of a soil's saturation capacity and reduce Mg saturation to less than 20%. Expected and claimed benefits of this practice of soil balancing include improved soil structure, decreases in weed pressure, and increases in crop yield. We applied various Ca and Mg rich minerals in a corn-soybean-small grain rotation in two Ohio soils over several years. Our treatments were designed to contrast the effects of different Ca to Mg ratios on the weed community and on soil properties. Our research is the first to provide evidence that Ca:Mg ratios in the soil can reduce density of weed seeds found in the soil. At the silt loam soil, broadleaf and grass seedbank densities were on average about 25% and 40% lower after the second year of gypsum applications, respectively, across crops. Weed emergence for the same soil showed a similar response. At the clay loam soil, grass seedbank densities were on average about 40% higher after the third year of epsom application across crops. Our experimental design enabled us to also investigate the claim of soil balancing proponents and farmers that the increases in crop yield they experienced were due to higher Ca:Mg ratios rather than pH correction. We examined crop yield in response to both pH and Ca and Mg saturation levels over 6 years and concluded that balancing the soil Ca and Mg levels did not impact corn or soybean yields but managing soil acidity did. Our results confirm that correcting excess acidity remains the fundamental reason to apply limestone as a tool to improve crop yields. Previously reported research from our project had (open full item for complete abstract)

Bachelor of Science in Education, Ashland University, 2012, Biology/Toxicology

Different soil types display a wide range of nutrient content, microbial abundance and diversity. Many of the microbes viable in soil have practical functions in the agricultural and medical fields while others are pathogenic. Garden topsoil, potting soil, forest soil, compost and manure were the five soil types investigated in this study for bacterial abundance, species diversity, and nutrient content. We hypothesized that manure and compost would have the most nutrients and be highest in number and diversity of bacteria. Likewise, we hypothesized that potting soil would be low in all three areas. Each soil sample was diluted, plated on Plate Count Agar and incubated at 37oC for 2 days in order to maximize the number of colonies able to grow on the media. The bacteria count was determined by plate count assay and the microbial abundance by using 16S rDNA to sequence isolated species and compare the number of genera present in each soil type. A qualitative nutrient analysis was conducted to evaluate the relative nutrient content of each soil type. It was determined that the compost was richest in nitrate, phosphorus and potassium, while the other soils were low in all three. The manure exhibited a significantly higher bacterial count than all the other samples. Potting soil, compost, garden topsoil and forest soil followed with less significant variance. Similarly, the manure represented the greatest number of genera from the 16S rDNA sequencing than the other samples.

Master of Science, The Ohio State University, 2021, Environmental Science

Soil health indicators are commonly used by researchers to understand how various soil properties are functioning. However, many new indicators have not been applied on working farm conditions and it is not well understood how these novel indicators may be useful to farmers in their management decision-making. This research took an integrated approach combining social science methods and biophysical soil testing to understand the use and value of soil health indicators to farmers in Ohio. A total of 19 soil health parameters were measured and reported back to farmers to discuss how these data could inform their future management decisions and to understand which indicators are most useful to farmers. Interviews were conducted with 20 row crop farmers to gather their insights on the utility of soil health indicators, as well as their management decisions following the 2019 growing season. Ultimately, the research evaluated how soil health indicators varied across selected fields the farmer deemed best and most challenging. This research also assessed which indicators aligned best with farmer perceptions of the soil health data and if the soil health indicators influenced adoption of new management practices among farmers. Findings from the research indicate that biological soil health indicators such as soil protein, respiration (MinC), and permanganate oxidizable carbon (POXC) were able to distinguish between best and most challenging field, were more sensitive indicators than others, and were most aligned with farmer perceptions of their fields. Additionally, this study found that while farmers found many biological indicators insightful, they did not provide sufficient information to alter any change in management. Overall, this study highlights the importance of interdisciplinary work by integrating social and natural sciences to gain a comprehensive assessment of farmers' perceptions and practices in relation to agricultural (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2021, Chemistry

This study explores the use of shallow subsurface soil spectroscopy in two different contexts: at archaeological habitation sites and at forensic sites where the presence of clandestine human burials is suspected. In the archaeological site characterization project, in situ shallow subsurface soil spectroscopy is employed to survey Native American archaeological sites in Kansas: Tobias East, and Tobias West. The resulting spectra enable the chemical characterization of the anthropogenic features. A reflectance probe attached to a mobile instrument recorded near infrared and visible diffuse reflectance spectra at each site on a grid pattern for a range of the depths from the surface down to 1 meter deep. Principal component regression and partial least square regression involving the limited set of lab analyses of soil cores enabled the construction of a chemometric model capable of estimating chemical species concentrations on the full 3D grid of spectral data. Significant archaeological features can be characterized without excavation using this method. In the forensic project, attenuated total reflectance (ATR) Fourier transform infrared (FTIR) mid infrared spectra and diffuse reflectance near infrared spectra were used to identify the presence of the decomposition products of human burials in soil samples taken from controlled forensic research facilities. Spectra of several different types of soil samples were acquired to determine how mid infrared (MIR) and near infrared (NIR) spectra can be used to detect adipocere constituting fatty acids in the following soils: soil with added fatty acids of known concentrations; soil taken from the vicinity of decomposing human cadavers on the surface at the Facility for Outdoor Research and Training (FORT) at University of South Florida; soil collected from graves at the Southeast Texas Applied Forensic (STAFS) facility in Texas; and in situ NIR spectroscopy at the STAFS graves and at a local historic grave site. The pr (open full item for complete abstract)

Master of Science, The Ohio State University, 2021, Environment and Natural Resources

Soil quality is defined as the soil's capacity to function within natural or managed ecosystems to sustain plant-animal-human health. It can be inferred from the quantification of soil properties which can be combined into a soil quality index (SQI). An SQI is a value that combines soil physical, chemical, and biological characteristics and scores the soil's “fitness to function”. Soil management practices (SMP), which differ depending on the landholder's agenda, can increase or decrease soil carbon (C) storage, which is an important parameter used for SQI calculation. Therefore, the objectives of this study were: (1) to evaluate the impact of SMP on physicochemical properties in an avocado orchard (AVO) and a tropical pumpkin/bean (TPB) plot and (2) to develop an SQI for each system. The study was conducted in the Juana Diaz Agricultural Experimental Station located in the south-central coast of Puerto Rico and the predominant soil series was San Anton. Both systems scored 0.55 on the 0 to 1 SQI scale, suggesting that higher soil C content does not imply an improvement in soil physicochemical quality. However, reduced tillage operations and natural ground cover have a positive impact on soil quality indicators, but not on soil physicochemical quality itself for this study. Future research priorities should be directed towards the evaluation of soil taxonomical characterization on soil quality and determine its significance if any.

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

Agricultural fields in Northwest Ohio and the Maumee River watershed are frequently tile drained and fertilized with phosphate to optimize plant growth. Phosphate is often lost from fields via surface runoff and tile drainage, either with particulate soil matter or as dissolved reactive phosphate. Soil health, aided by enzymes produced by microorganisms and plants, can influence the retention and loss of phosphate. Stable oxygen isotopes may provide a non-invasive way of measuring the biological turnover rate of phosphate in soils over longer time scales than previous methods. The ability of oxygen isotopes in phosphate to measure biological turnover was examined in a study with three fields in the Maumee River watershed from fall 2016-summer 2017. Samples were collected after fall tilling and fertilization, and before and after spring planting and fertilization. Soil nutrients and metal concentrations were analyzed as well as oxygen isotope analysis from soil phosphate, soil pore-water, and tile water. Overall, sites had high nutrient and metal concentrations and low levels of phosphate recycling relative to the overall pool of phosphate, based on oxygen isotope analysis. Soil samples did not reach equilibrium with soil pore-water. The most recycled sample collected, a tile drain sample collected five months after fall fertilization, was still about 80% fertilizer. The results suggest that sources of phosphate can be detected for long periods of time in agricultural fields under specific circumstances and that phosphate ion interactions with metal oxides may help explain the lack of equilibrium observed. Oxygen isotope studies of phosphate in soil could help researchers and field managers better understand the mechanisms behind the effects of various best management practices (BMPs) on nutrient runoff.

Master of Science, University of Toledo, 2018, Biology (Ecology)

A principle driver of water-polluting harmful algal blooms (HABs) in agricultural watersheds is fertilizer phosphorus (P) runoff from farm fields. Because P is essential to plant growth, eliminating P application is infeasible. However, much of the P that is added to soils as fertilizer binds tightly to soil particles and is relatively unavailable to plants. In natural systems, microbial and faunal decomposers can increase soil P availability to plants. In agricultural systems, stimulating these organisms may help maintain P availability with decreased P application rates, thereby increasing P application efficiency while reducing runoff potential. We tested the hypothesis that stimulating soil fauna with sodium (Na+) and microbes with carbon (C) would increase soil P availability to plants. We added corn stover and Na+ solution to plots in conventionally-managed corn fields in Northwest Ohio. Stover treatments increased microbial biomass and activity and Na+ and stover combined increased soil faunal activity. However, even in both control plots and plots with stimulation of soil microbes and fauna, soil biological activity was low, and was not correlated with P availability. Therefore, in fields with low levels of decomposer activity, organisms may play a limited role in soil P cycling. In these types of ecosystems, treatments to stimulate decomposers already in those systems may be ineffective in reducing P runoff potential, at least in the short term.

Master of Science, The Ohio State University, 2018, Horticulture and Crop Science

In Ohio, many organic farmers use the term `balancing' to express the rationale of using a wide variety of soil amendments to improve soil quality and plant health. Soil balancing or the base cation saturation ratio (BCSR) approach is a method first proposed more than 100 years ago that aims to achieve the `ideal soil'. William Albrecht in the 1970's concluded that if saturation of the major exchangeable cations is 65-85% for Ca, 6-12% for Mg, and 2-5% for K, plant nutrition will be balanced. Research conducted by Zwickle et al. (2011) indicated that many organic farmers believe balanced soils produce higher quality crops and have diminished weed infestations compared to unbalanced soils. For many farmers, soil balancing includes using amendments thought to enhance soil biology and increase the soil's capacity to store and release minerals needed by plants. Combined mineral and these organic/bio-active soil products can be very costly, as much as US $1000-1250/ha in the first year. While farmers believe they are benefiting from these expenditures, there is no objective evidence to confirm their belief. I conducted on-farm studies at six locations in Northeast Ohio, with the overall goal of determining the effect of gypsum, with or without “biological stimulants”, on the soil microbial community, crop quality, weed populations, and soil chemical characteristics. Soil seed bank and soil health/biological properties were measured, including soil respiration, active carbon, protein content, microbial biomass, and complete mineral analysis. Crop foliage for nutrient analysis, and crop quality was determined after harvest. Differences in final soil nutrient levels, base saturation, crop and weed community effects were influenced more by the farm than by the treatments applied. After two years, soil sulfur levels were significantly higher in plots amended with gypsum. Failure to detect treatment response by other mineral amendments suggests the relatively narrow difference (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2016, Environment and Natural Resources

Management of soil hazards in urban areas requires strategies that are scientifically effective and accepted by both the general public and public health regulators. Soil management options must consider all three of these components during evaluation. The concept of managing soil hazards to reduce contaminant exposure must be expanded to include considerations of soil function and soil health following remediation. Bioavailability assessments must be included with soil hazard assessments to improve hazard characterization. Soil hazard and soil health indicators can be combined in a comprehensive index, though the relative importance of each factor within the index will be site specific. Several recent studies have quantified contaminants in soil, such as lead (Pb), arsenic (As), and polycyclic aromatic hydrocarbons (PAHs), in many urban areas. When these findings are coupled with slow regulatory movement on potential management strategies, the public's perceived risk for potential exposure may increase. Such scenarios across the United States may reduce public support for widespread contaminant cleanup. Innovative interdisciplinary research initiatives are needed to: (1) evaluate potential contaminants and factors that contribute to healthy, functioning soil, (2) facilitate public and regulatory acceptance of potential soil hazards and treatments, and (3) communicate the public health implications of viable cleanup activities. These studies are particularly needed in vulnerable urban areas that demonstrate variable soil contaminant concentrations over small geographic spaces. Characterizing and addressing these soil contaminants will contribute to and benefit our society from public health, social, environmental, and economic perspectives. Soil contaminants and their impacts can be evaluated within the context of other exposures and individual characteristics, such as proposed in the developing field of exposome public health research. The results from this diss (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2013, Environment and Natural Resources

The formerly industrial cities of the North Central region have become a rapidly expanding frontier for urban agriculture (UA) in the US. As populations in these cities have declined, a legacy of vacant land and properties has been left behind. UA has emerged as an important means of utilizing vacant land and is capable of producing numerous societal benefits. Urban soils, however, are highly variable and subject to high levels of degradation. An understanding of local soil properties is a basic starting point for sustainable agriculture, yet very little information exists about the characteristics of urban soils or options for their management. Through this dissertation project I have worked to address this unique knowledge gap by generating important background data and management recommendations for urban soils. The first chapter of this dissertation synthesizes available information on topics that are key to this project, including: the extant of vacant land and UA in the region around Ohio, management of UA systems, soil quality (SQ) assessment and soil properties and ecology in urban areas. The second chapter presents an experiment that evaluated soil properties in an urban soil following the demolition of vacant houses, as well as the ability of amendments produced from organic waste materials to improve SQ and support vegetable crop production under these conditions. The experimental site was located in a series of adjacent vacant urban lots in Youngstown OH and utilized a split-plot design to test differences in soil properties and crop growth. Main plots tested the effect of organic matter treatments while the split plots evaluated raised bed cultivation. The experiment was conducted during the 2011 and 2012 growing seasons and soil physical, chemical and biological properties were measured at the initiation and conclusion of the experiment. A SQ index was developed using multivariate analyses and scoring functions from the Soil Management Assessment Fra (open full item for complete abstract)

Master of Science, The Ohio State University, 2009, Natural Resources

This study was composed of two research components that examined the effects of tallgrass prairie land use changes on soil organic C (SOC). The central objective of the first study was to examine changes in SOC and a suite of soil quality parameters in former agricultural soils now under restored tallgrass prairie. This research was conducted at the Prairie Nature Center, on the OSU Marion campus in northwest Ohio. Soils from 31 year, 13 year, and 8 year- old prairies, and adjacent agricultural and lawn soils were analyzed. These soils demonstrated significant increases in SOC concentration, particulate organic matter (POM), water stable aggregation (%WSA), aggregate mean weight diameter (MWD), total porosity (ft), and available water capacity (AWC), and significant decreases in soil bulk density (ρb) associated with time under tallgrass prairie. The second research component observed long and short-term effects of the conversion of remnant tallgrass prairies to wheat production, in north central Kansas. Total C, microbial biomass C (MBC), and a particle size fractionation of SOC were used as indices of change. Long-term sites showed changes in all fractions analyzed, while only MBC showed significant change in the short-term study. This study provides further evidence that perennial plant communities store and cycle C, and maintain ecosystem processes at far greater levels than annual plant communities.

Doctor of Philosophy, The Ohio State University, 2004, Soil Science

Soil quality indices are useful tools for assessing agronomic/ biomass productivity and ascertaining temporal changes in soil properties in relation to land use and management. This study was conducted in the Lake Victoria region in Masaka, Uganda to: (a) identify key soil properties that impact soil quality and agronomic productivity; (b) evaluate soil quality-management inter-relationships; (c) evaluate the use of soil reflectance as a soil quality indicator, and (d) determine the cost and returns of different cropping systems. Bulk and core soil samples were collected from the 0-20 and 20 – 50 cm depths, from the farmers' fields, in order to determine soil organic carbon, nitrogen, calcium, phosphorous, magnesium, pH, _13C, _15N, coarse fragments, soil bulk density and soil texture. Saturated hydraulic conductivity (Ks) was determined in the field using a tension infiltrometer and soil depth using an auger. The soil degradation rating was assessed by assigning parametric values to levels of SOC, soil bulk density, Ks, soil texture, soil pH, soil depth and the proportion of coarse fragments in the top soil and these parameters were utilized to develop a single index. Air dry samples were scanned using a spectrometer and the first derivative of the spectral data was calibrated against the measured soil properties. Results indicated that soil quality was affected by SOC, soil depth and Ks. No direct effects of management on soil quality were discerned. Good predictions of several soil properties were obtained using the spectral data. Although a majority of farmers planted bananas as the first choice crop, the highest net returns were obtained from coffee while the highest costs were measured for bananas implying that food self sufficiency was the major determinant of the choice of crop to be grown. It was recommended that grasslands must not be converted to agricultural land use because of their high susceptibility to soil degradation and that farmers be sensitized (open full item for complete abstract)

Master of Science, The Ohio State University, 1913, Graduate School

Master of Science, The Ohio State University, 2005, Graduate School

Doctor of Philosophy, The Ohio State University, 2024, Environmental Science

Historical and current anthropogenic activity combined with land turnovers and rampant vacancies have increased human exposure risk to contaminants. This exposure risk disproportionately affects lower income communities and can have detrimental impacts on human health, particularly children. A management solution is needed to address this widespread contamination of vacant lots. Additionally, federal and state regulators continue to lower residential soil Pb standards which will likely require new risk-based approaches to address urban soil Pb contamination. This dissertation examines three different amendment types (P amendments, Fe oxide containing amendments, and potassium permanganate (KMnO4)) for their ability to address urban Pb soil contamination and reduce human health exposure risk. Remediation strategies that can address both organic and inorganic pollutants are also needed. This is addressed in Chapter 3. This dissertation is written as a series of manuscripts to be submitted to the appropriate journals; this will be reflected by slight differences in formatting. In Chapter 1, readily available P sources (biosolids incinerator ash, poultry litter, biosolids compost, and triple super phosphate) of varying solubility were assessed as soil amendments to reduce Pb bioaccessibility and serve as an inexpensive remediation strategy for urban soil. Contaminated soil from Cleveland, OH was treated with the P soil amendments at a 1:5 Pb:P molar ratio and incubated for 3 months. A slurry analysis was also conducted to assess reduction in bioaccessible Pb independent of time. Pb bioaccessibility was evaluated using US EPA Method 1340 at pH 1.5 and the Physiologically Based Extraction Test (PBET). Treatments were largely found ineffective regardless of IVBA extraction method, incubation duration, slurry analyses, or P source. Method 1340 had one significant treatment (combined poultry litter and BIA) but only resulted in a 8% IVBA Pb reduction. The same treatmen (open full item for complete abstract)

Master of Science (MS), Ohio University, 2023, Plant Biology (Arts and Sciences)

A green roof provides different benefits in an urban environment, like habitat, stormwater management, reduced energy usage, aesthetic values, and carbon storage. To understand the carbon storage capacity of green roofs, it is important to understand the amount of CO2 released (efflux) and taken up by the green roof. So, I measured and compared the above and belowground biomass, soil CO2 efflux (respiration), and associated soil parameters between the green roof and the prairie site to understand how environmental variables like soil temperature and moisture on the green roof influence CO2 efflux. The green roof substrate was significantly warmer than the prairie soil, and CO2 efflux from the green roof was less sensitive to temperature (i.e., had lower Q10) than the prairie site. I hypothesize that the porosity of the green roof substrate, which accounts for its lower water-holding capacity and volumetric moisture content, lowered the potential evapotranspiration and caused higher temperature and greater variation in temperature on the green roof. The green roof also had comparatively higher variation in substrate temperature, consistent with greater variation in CO2 efflux. The differences in the plant activity led to the major differences in the CO2 efflux between the green roof and the prairie site. Higher above and belowground (root biomass) on the prairie site led to higher total CO2 efflux on the prairie site as higher aboveground biomass can lead to increased photosynthates for the roots and higher root exudates along with the higher litter input, all of which can increase autotrophic and heterotrophic respiration. However, after accounting for the differences in root biomass on soil CO2 efflux (i.e., dividing efflux by root biomass), the green roof had higher efflux than the prairie sites, indicating a higher contribution of heterotrophic sources to CO2 efflux at the green roof. Since the green roof at Schoonover Center is unique due to its location, clima (open full item for complete abstract)