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  • 1. Franks, Matthew The Role of Soil Organic Matter and Fe- and Mn-(Oxy)Hydroxide Minerals in Agriculture: Implications on Nutrient Dynamics

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

  • 2. Ackerson, Nana Osei Iopamidol as a Precursor to DBP Formation in Drinking Water as a Function of Natural Matter and Bromide

    Doctor of Philosophy, University of Akron, 2017, Engineering

    Iopamidol, one of the most commonly used and detected iodinated X-ray contrast media in water sources, is inert in the human body but reacts and degrades in the presence of aqueous chlorine to form highly cytotoxic/genotoxic disinfection by-products (DBPs). The objectives of this study were to investigate (1) the effect of iopamidol on the formation and speciation of DBPs in multiple source waters (SWs), (2) the formation of TOX/DBPs in SWs containing iopamidol, bromide, and chlorinated oxidants, (3) the impact of prechlorination time on TOX/DBP formation during chloramination of SWs containing iopamidol and (4) kinetic modeling of TOX, iodate, and DBP formation due to chlorination of iopamidol. SWs from Akron, Barberton, and Cleveland Water Treatment Plants containing iopamidol or iopamidol/bromide were dosed with chlorinated oxidant at pH 6.5-9.0 for 0-72 h. The study showed that the yields of either TTHMs or HAAs exhibited a strong correlation with humic, fulvic, and combined fulvic and humic fractions at pH 7.5. Similarly, the yields of TOCl/UTOCl exhibited strong correlation with SUVA254 at pH 7.5. Although iopamidol directly formed CHCl3, TCAA, and CHCl2I in chlorinated water; iopamidol exhibited minimal impact on DBP formation compared to NOM. In the presence of bromide and aqueous chlorine, iopamidol formed more DBPs. TOI loss was unaffected by the concentrations of bromide. TOCl and TOBr, respectively decreased and increased with increasing bromide concentration but was unaffected by iopamidol concentration. As bromide concentration increased the concentrations of fully brominated DBPs increased while fully chlorinated DBPs and CHCl2I decreased. CHBrClI increased with increasing bromide concentration in CSW. Also, iodo-DBPs increased with increasing iopamidol concentration. Generally, in the presence of bromide and iopamidol, lower amounts of DBPs including iodo-DBPs were formed in chloraminated SWs then chlorinated SWs. In SWs chlorinated before (open full item for complete abstract)
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    Committee: Stephen Duirk (Committee Chair); Christopher Miller (Committee Member); Teresa Cutright (Committee Member); Chelsea Monty (Committee Member); John Senko (Committee Member) Subjects: Chemistry; Civil Engineering; Environmental Engineering; Water Resource Management

  • 3. Wei-Haas, Maya The Influence of Dissolved Organic Matter on the Fate of Polybrominated Diphenyl Ethers (PBDEs) in the Environment

    Doctor of Philosophy, The Ohio State University, 2015, Geological Sciences

    Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardant that is ubiquitous in the environment and detected in a variety of both biotic and abiotic samples. Mounting concern over the last several decades over the toxic effects of PBDEs has resulted in a global cessation in their production. Nonetheless, PBDEs will continue to be detected in the environment due to their emission from ongoing use and recycling of PBDE-containing products. PBDEs are distally transported to the Arctic, but little is known about the fate of these compounds in Arctic surface waters, especially in the presence of dissolved organic matter (DOM). The present study is focused on quantifying the influence of DOM in the binding (i.e. dissolved organic carbon—water partition coefficients, KDOC) and abiotic photodegradation rates, mechanisms, and product formation of PBDEs under environmentally relevant conditions. My results indicate that PBDEs strongly bind to DOM, whereby the measured KDOC were nearly an order of magnitude lower than previously reported values for the same PBDE congeners in soil or commercially available organic matter. The KDOC values measured in the present study range from 103.97 to 105.16 L Kg-1 of organic carbon, which increase with congener hydrophobicity. This association with DOM facilitates PBDE photodegradation, resulting in at least a factor of 2 increase in rate constants for the indirect relative to direct photolysis of BDE-47. Photodegradation rates are strongly positively associated with DOM aromaticity and negatively correlated to dissolved oxygen. As such, photodegradation likely occurs via reduction reactions with excited triplet DOM and is expected to be insensitive to reactive oxygen species. Finally, the efficacy of fluence-based rate constants is explored for the direct comparison of experiments conducted under variable natural and artificial sunlight. Using the irradiance normalization method, discussed in t (open full item for complete abstract)
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    Committee: Yu-Ping Chin (Advisor); Kristopher McNeill (Committee Member); William B. Lyons (Committee Member); John Lenhart (Committee Member) Subjects: Environmental Science

  • 4. Chen, Dong Ultrasonic Control of Ceramic Membrane Fouling Caused by Silica Particles and Dissolved Organic Matter

    Doctor of Philosophy, The Ohio State University, 2005, Civil Engineering

    This study systematically investigated the mechanism and efficiency of the ultrasonic control of gamma-alumina ceramic membrane fouling caused by silica particles and dissolved organic matter (DOM). Ultrasound at 20 kHz was applied to a cross-flow filtration system. First, ultrasonic cleaning was explored with filtration of silica particles to investigate influence of both particle characteristics and ultrasonic factors on cleaning. Experimental results indicated that more effective control of fouling occurring at low particle concentrations, hydrophilic particles, and large particle sizes based on measurements of sound wave intensity, images of the cavitation region, and force balance analysis of a particle deposited on the membrane. In addition to the effect of particle characteristics, ultrasonic factors affecting membrane cleaning were explored. Optimal cleaning occurred when the membrane was outside but close to the cavitation region. However, damage in the form of pits and cracks were found when the membrane was within the cavitation region. An increase in the filtration pressure resulted in less improvement in permeate flux of ultrasound. Furthermore, pulsed ultrasound with short pulse intervals resulted in a relative permeate flux improvement close to that of continuous sonication. Second, besides sonophysical cleaning of particle fouled membranes, membrane cleaning was also explored by studying sonochemical reactions of DOM. Property changes of Aldrich and Pahokee peat DOM at different ultrasonic frequencies and energy densities were systematically investigated. Exposure of DOM to ultrasound resulted in decreases in hydrophobicity, aromaticity, and molecular weight, while DOM acidity increased. However, at low ultrasonic frequency (20 kHz) and low energy density, sonochemical transformation of DOM was insignificant. Finally, the effect of solution chemistry on ultrasonic control of membrane fouling caused by DOM and silica particles was examined. Experiment (open full item for complete abstract)
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    Committee: Linda Weavers (Advisor) Subjects: Engineering, Environmental

  • 5. Brooker, Michael Water Contaminants of the Lake Erie Watershed

    Doctor of Philosophy, The Ohio State University, 2018, Environmental Science

    Streams and rivers act as conduits, transporting pollutants from their sources to downstream drainage basins. The Lake Erie watershed is dominated by agricultural land use. As a result, there are many concerns over pollution sourced from upstream agroecosystems. Among the principle issues in the region, phosphorus and other nutrient pollutants have been faulted for stimulating and/or supporting the frequency and magnitude of recurrent harmful algal blooms occurring in the western Lake Erie basin. Phosphorus pollution originates from a variety of point and nonpoint sources, however specific estimates of individual source contributions have proven elusive. Better distinguishing between the sources of pollution, as well as an improved ability to track transport through the watershed is essential for managing nutrient loads. One promising and new approach to elucidating source contaminants is the organic phosphorus fraction of dissolved orgnaic matter (DOM). Point and non point sources may exhibit unique DOM or dissolved organic phosphorus (DOP) signatures, tha allows for the differentation between sources, either through signature analysis or the application of marker molecules. Here, electrospray ionization Fourier-transform mass spectrometry (ESI FT-ICR-MS) was used to analyze the DOM and DOP signatures from nutrient pollution sources in the Lake Erie watershed. Three marker compounds were distinct to sources were proposed for use in tracking the presence of source contamination. From this source signature analysis, differences in DOM was next evaluated along a mixing profile for a Lake Erie tributary. The ability to detect DOM formulae upstream to downstream sites was assessed. Compounds detected in higher abundane upstream were more likely to be detected at downstream locations. The mass spectra signals of merging branches appeared to be mixed linearly into several confluence points. In addition to nutrient sources influencing Lake Erie water quality, there are c (open full item for complete abstract)
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    Committee: Paula Mouser (Advisor); Jon Witter (Advisor); Gil Bohrer (Committee Member); Virginia Rich (Committee Member) Subjects: Environmental Science

  • 6. Looft, Torey MOLECULAR CHARACTERIZATION OF MICROBIAL COMMUNITIES IN LAKE ERIE SEDIMENTS

    Master of Science (MS), Bowling Green State University, 2005, Biological Sciences

    Microorganisms perform important roles in elemental cycling and organic decomposition, which are vital for ecosystems to function. Lake Erie offers a unique opportunity to study microbial communities across a large environmental gradient. Lake Erie consist of three basins and is affected by allochthonous inputs of dissolved organic matter (DOM) that increase to the west. In addition, the Central Basin of Lake Erie is characterized by an area dominated by a Dead Zone, which experiences periodic hypoxic events. To evaluate patterns of microbial diversity, environmental samples from eleven sites were selected for PCR amplification, cloning and sequencing of 16s ribosomal DNA genes from microbial species. Samples included inshore sites from the Western, Central and Eastern Basins as well as from the Dead Zone. Characterization of environmental DNA sequences was performed through sequence database searches and phylogenetic analyses. Biodiversity indices and measures of sequence diversity were obtained. Results from this study demonstrated considerable levels of spatial variability of microbial communities throughout Lake Erie. Characterized species included bacterial groups with diverse metabolic capabilities and key members involved in the cycling of nutrients. The relative preponderance of Gammaproteobacteria in the Western and Central Basins, but not in the Eastern Basin, may reflect the presumably widespread carbon substrate range found in the Western and Central Basins due to the greater number of allochthonous inputs. East and Central Basins showed similarities in species diversity, while the Dead Zone represented the most distinct group. These results are consistent with the idea that microbial community structure may be modulated by DOM inputs and environmental conditions.
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    Committee: Juan Bouzat (Advisor) Subjects:

  • 7. Gaffney, Katherine Spatial and Seasonal Variability of Dissolved Organic Matter and Nitrogen in Lake Erie Tributaries

    Master of Science, The Ohio State University, 2024, Environment and Natural Resources

    It is important to understand how environmental factors drive variability in aquatic nutrient cycling in streams. Controls on variability in production and transformation of dissolved organic matter (DOM), a carbon-based nutrient, are not well understood on spatial scales spanning many streams. This knowledge gap leaves questions as to how environmental factors influence DOM characteristics. In water year 2023, we investigated nitrogen and carbon chemistry seasonally in 80 tributaries on the United States side of Lake Erie. Watershed area and modeled discharge had no clear effect on total dissolved nitrogen (TDN) or DOM concentrations. Land use was a significant factor influencing stream chemistry; watersheds with different dominant land uses produced different seasonal chemistry patterns and had different environmental factors influencing stream chemistry. In watersheds dominated by agricultural land use, nitrate was the dominant form of nitrogen contributing to high TDN concentrations, likely driven by fertilizer use. DOC concentration and chemistry varied moderately with season and were impacted differently in watersheds with greater forest cover as compared to watersheds with greater cover of anthropogenically impacted land uses. Dominant land use of a watershed dictated how watershed factors, such as soil hydrology, watershed size, and degree of natural or anthropogenic land use, influenced stream chemistry, indicating that differences in DOM chemistry may be due to differential processes controlling DOM source and transformation.
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    Committee: Rachel Gabor (Advisor); Rachel Eveleth (Committee Member); Gil Bohrer (Committee Member); Matt Davies (Committee Member) Subjects: Aquatic Sciences; Biogeochemistry; Environmental Science

  • 8. Fatema, Umme The Role of Dissolved Organic Matter on Phosphorous Sorption onto Iron-Enhanced Activated Alumina Media using In-Field and Flow-Through Column Experiments

    Master of Science (MS), Bowling Green State University, 2022, Geology

    The Western Lake Erie Basin (WLEB) has been experiencing harmful algal blooms due to increases in dissolved reactive phosphorous (DRP) from agricultural land in the Maumee River watershed. Agricultural best management practices (BMPs) can be useful to mitigate the DRP loads; nevertheless, DRP is not always fully removed by in-field BMPs. Phosphorous (P) removal structures can be filled with phosphorus sorption materials (PSM) such as iron and aluminum oxides and can be placed at the junction of runoff and subsurface drainage to trap DRP from tile drainage. However, dissolved organic matter (DOM) from the agricultural farmland might compete with phosphate ions (PO43-) at the adsorption sites in the media, reducing its lifetime and efficiency. Therefore, laboratory flow-through column experiments were conducted to determine whether DOM is affecting P sorption onto iron enhanced activated alumina media (Alcan). The experiments were informed by field data collected from a regional farm. Alcan (Al/ Fe (hydro) oxides) media was efficient in removing PO43- coming into the filtering system and thereby, flow-through column experiments were able to determine a discrete P removal percentage efficiency of 83.32%, 68.26%, 66.54%, 57.16% and 41.27% by the end of treatment I (5mg L-1 PO43- only), treatment II (5mg L-1 PO43- and 5 mg L-1 DOM), treatment III (5mg L-1 PO43- and 10 mg L-1 DOM), treatment IV (5mg L-1 PO43- and 20 mg L-1 DOM), and treatment V (10mg L-1 PO43- and 20 mg L-1 DOM), respectively. Moreover, from exponential regression analysis of P removal curves for each treatment, it was measured that a total cumulative of 231.45 gm, 92.65 gm, 92.06 gm, 65.998 gm and 91.476 gm of P per kg PSM can be added to treatment I, II, III, IV and V, respectively, until the media gets fully saturated, i.e., concentration of influent PO43- would be equal to the effluent PO43- concentrations. It is evident that DOM is competing with PO43- decreasing PO43- sorption onto the Alcan media. (open full item for complete abstract)
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    Committee: Angélica Vázquez-Ortega PhD (Committee Chair); Enrique Gomezdelcampo PhD (Committee Member); Margaret (Peg) M. Yacobucci PhD (Committee Member) Subjects: Environmental Geology; Environmental Science; Environmental Studies; Geochemistry; Geology; Soil Sciences

  • 9. Laszakovits, Juliana Investigating the Impact of Permanganate Pre-Oxidation on Dissolved Organic Matter During Drinking Water Treatment Using Ultrahigh Resolution Mass Spectrometry

    Doctor of Philosophy, The Ohio State University, 2021, Civil Engineering

    Dissolved organic matter (DOM) is ubiquitous in natural and engineered aquatic systems. DOM can be problematic during drinking water treatment due to its ability to scavenge oxidants and react with chlorine to form carcinogenic disinfection byproducts (DBPs). Drinking water treatment plant operators aim to minimize DBP formation by removing DOM (alum coagulation and activated carbon sorption) or altering DOM composition (permanganate oxidation). While permanganate pre-oxidation has been claimed widely to be an effective strategy to reduce DBP formation, its impact on drinking water treatment and subsequent DBP formation remains poorly understood. Here, a novel ultrahigh resolution mass spectrometric approach was used to characterize DOM by combining data from multiple ionization techniques to provide greater insight on DOM molecular level changes induced by treatment. In Chapter 2, this approach was applied along with Fourier Transform-infrared spectroscopy and ultraviolet-visible spectroscopy to understand which DOM components react with permanganate for two DOM isolates (a terrestrial isolate and a microbial isolate). Aromatic and nitrogenous components were found to react with permanganate and help explain previously observed trends between permanganate-DOM reaction rates and SUVA-254 values as well as why algal-derived DOM can efficiently scavenge permanganate. In Chapter 3, the impact of permanganate pre-oxidation on the response of DOM to subsequent treatments was investigated using ultrahigh resolution mass spectrometry and bulk characterization techniques for three DOM isolates that represented different DOM source types: terrestrial, algal-impacted, and wastewater effluent-impacted. Permanganate pre-oxidation enhanced removal of aromatic components by coagulation and activated carbon sorption because it added negatively charged functional groups that interacted more favorably with sorption sites. It was also observed that complimentary treatments (i.e., coa (open full item for complete abstract)
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    Committee: Allison MacKay (Advisor); John Lenhart (Committee Member); Linda Weavers (Committee Member); James Cowan (Committee Member) Subjects: Environmental Engineering

  • 10. Wilkins, Keiko The Importance of Dissolved Organic Matter Source on the Survival and Growth of Juvenile Daphnia

    Master of Science, Miami University, 2020, Biology

    Shifts in forest composition could have significant effects on freshwater zooplankton due to changes in quality of inputs of terrestrially-derived Dissolved Organic Matter (DOM). DOM has been shown to have concentration dependent effects on primary production, but no consistent concentration dependent effects on zooplankton growth rates, raising questions about the potential importance of DOM source. Red maple (Acer rubrum), a native tree, and Amur honeysuckle (Lonicera maackii), an invasive shrub, were used to test the effects of DOM source on juvenile Daphnia ambigua. Amur honeysuckle-derived DOM was expected to have greater negative effects. Bioassays were conducted in the presence or absence of algae with no additional DOM, or red maple or Amur honeysuckle-derived DOM. Both Amur honeysuckle and red maple had negative effects on growth rates in the presence of algae with red maple inducing significantly lower growth rates. Red maple-derived DOM also had negative effects on survival. The negative effects seen in the presence and absence of algae provided evidence for both indirect effects likely due to phytotoxicity and direct negative effects respectively. Future studies accounting for DOM source could enhance our understanding of the complex roles of DOM in regulating consumers in aquatic ecosystems.
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    Committee: Craig Williamson (Advisor); Maria Gonzalez (Committee Member); Karsten Mauer (Committee Member) Subjects: Biology; Ecology; Freshwater Ecology; Limnology

  • 11. Berry, Nicole DOES DISSOLVED ORGANIC MATTER PROTECT MOSQUITO LARVAE FROM DAMAGE BY SOLAR ULTRAVIOLET RADIATION?

    Master of Science, Miami University, 2019, Biology

    Northeastern North America has experienced an increase in both the abundance and geographic distribution of mosquitoes, and at the same time over a doubling of dissolved organic matter (DOM) concentrations in some inland water bodies. These increases in DOM reduce underwater exposure to solar ultraviolet radiation (UVR), which can provide a refuge for water borne pathogens and diseases. Yet almost nothing is known about the effects of solar UVR and DOM on disease vectors such as mosquito larvae. Though mosquito larvae are most common in shaded habitats, essentially nothing is known about their susceptibility to damage by solar UVR. I hypothesize that 1) solar UVR kills mosquito larvae, (2) exposure to DOM reduces mortality by solar UVR, and 3) larvae lack photoenzymatically activated DNA repair. Experiments using UV-lamps and solar radiation manipulated the presence of DOM and UVR. Larval survivorship significantly decreased in the presence of solar UVR (p < 0.001). The presence of DOM during UVR exposure significantly increased survivorship (p<0.001), and unexpectedly, DOM pre-exposure significantly increased survivorship following exposure to solar UVR (p<0.001). There was no evidence of PER (p =0.444). These findings confirm that DOM provides protection against damaging solar UVR for mosquito larvae, important disease vectors that are increasing with increases in DOM in northeastern North America.
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    Committee: Craig Williamson (Advisor); Fisher Thomas (Committee Member); Rypstra Ann (Committee Member) Subjects: Biology

  • 12. McAdams, Brandon Relationships between reduced sulfur and dissolved organic matter in prairie pothole wetlands

    Doctor of Philosophy, The Ohio State University, 2017, Earth Sciences

    Mercury-gold amalgam and bismuth film electrodes (BiFE) were used to make the first cm-scale measurements of redox species in benthic pore waters of prairie pothole wetlands across a hydrologic gradient. Sulfide in pore waters increased across this system from negligible sulfide in hydrologically up-gradient recharge wetlands to 1000's of µM in down-gradient discharge wetlands. Use of Hg/Au and BiFE electrodes should allow for rapid in situ detection of redox active species, especially sulfide concentrations >500 µM, in pore waters over seasonal to decadal timescales. Such measurements are useful to understand important biogeochemical and environmental processes such as carbon cycling and contaminant attenuation tied to sulfur dynamics in these important ecosystems. Molecular weight (MW) and molar absorptivity at 280 nm (e280) was measured in DOM from wetlands in the prairie pothole region (PPR) isolated by different techniques as well as in the context of functional gradients within the PPR wetland system and previously established relationships for river, groundwater, and lake DOM. Little difference was observed in MW and e280 between XAD-8 and PPL SPE isolations of PPR wetland surface water DOM, and PPR DOM does not fit with previous correlations relating MW to e280. Trends in MW and e280 of PPR wetland DOM suggest that primary productivity and photo-bleaching of DOM in the surface waters of these wetlands provide labile DOM to fuel the active redox environments in the pore waters. Thus, the character of the DOM together with the sulfur gradient of prairie wetlands is influencing the chemistry that allows for abiotic incorporation of sulfur into DOM. Redox and adsorption were studied together to examine how sulfur-rich DOM in the surface waters will behave during transport through pore waters, as by sedimentation and/or hydrology. Reduction of prairie wetland DOM decreases its adsorption onto goethite and releases ferrous iron into solution. This adsorption be (open full item for complete abstract)
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    Committee: Yu-Ping Chin (Advisor) Subjects: Environmental Geology; Geochemistry

  • 13. Semones, Molly Dynamics in the reactivity and photochemical production of hydroxyl radical in treated wastewater effluent and aquatic dissolved organic matter

    Doctor of Philosophy, The Ohio State University, 2017, Environmental Science

    The hydroxyl radical (HO•) is a photochemically generated species that is important in the attenuation of organic contaminants in sunlit natural surface waters and in advanced oxidation processes (AOPs) used to treat drinking and wastewater. The steady state concentration of HO•, ([HO•]ss), in photochemical systems is typically measured indirectly using probe compounds. In this work, we investigate the use of caffeine as a photochemical probe for the detection of HO• in the presence of dissolved organic matter (DOM) solutions derived from allochthonous and autochthonous precursors using both the first order and initial rates approach to kinetic analysis to determine [HO•]ss in aqueous solution. Values for [HO•]ss are found to agree within a factor of two of values measured using terepthalic acid (TPA), a well-established probe for the detection of HO•, in the identical DOM solutions. Additionally, we find that caffeine is more selective for HO• than previously believed since it does not appear to undergo reaction with long-lived reactive transients as was formerly presumed. The presence of nitrate in wastewater effluent could play an important role in the formation of HO•, and therefore also in the fate of contaminants in sunlit receiving waters. We investigate the interplay between HO• formation derived from both effluent dissolved organic matter (EfOM) and nitrate (NO3-). The assumption of little to no interaction between NO3- and EfOM during HO• production (RHO•), needed to determine the contribution of DOM to hydroxyl radical formation in waters containing NO3- without extracting EfOM from the wastewater, is invalid. We based our findings on measurements of RHO• and [HO•]ss using benzene and caffeine as HO• probes in both whole wastewater effluent and solutions of EfOM isolated by solid phase extraction from the same effluent sample. The RHO• value measured for the isolate in the absence of NO3- (0.074 ± 0.009 (SE) nM s-1) is 1.5 fold higher than that found (open full item for complete abstract)
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    Committee: Yu-Ping Chin (Advisor); Terry Gustafson (Committee Member); Roman Lanno (Committee Member); John Lenhart (Committee Member) Subjects: Environmental Science

  • 14. Stuckman, Mengling Biotic Arsenic Mobilization in Natural and Anthropogenic Systems from Redox Transformations of Arsenic, Iron and Sulfur

    Doctor of Philosophy, The Ohio State University, 2014, Environmental Science

    The mobility of arsenic (As) is difficult to predict or determine in geological systems that have large spatial and temporal variations in biogeochemistry (e.g., redox, microbial communities and aqueous chemistry). To characterize As mobility under such conditions requires an understanding of As sorption behavior onto minerals, mineral-microbe interactions and microbially-driven As redox cycles, which can be gained through coupling detailed spectroscopy, microbiology and molecular biotechnology. In this study, two biotic arsenic mobilization investigations are detailed, one comprising processes in an engineered setting and the other in a natural system. In the first component of this study, microbially-mediated As release from spent drinking water adsorbents under simulated landfill conditions was evaluated using biotic incubations. Single cultures of microorganisms with different As, Fe and S reducing capabilities and growth medium amended by competitive anions were utilized in separate batch incubations to simulate landfills with geochemical and microbial variability. My results demonstrated that microbial As release was 100 times more significant than its abiotic control. Landfill conditions with high levels of phosphate and bicarbonate enhanced As bioreduction by solubilizing bioavailable As, resulting in significant As mobilization, which was further confirmed by thermodynamic calculations. Synchrotron-based micro-spectroscopy showed enhanced As co-precipitation with mackinawite (FeS) via sulfate reduction in S/P accumulated micro-scale hotspots. These results suggest screening tests to evaluate the environmental impact of As-containing solid waste disposal into landfills should consider microbial As release under simultaneous Fe and S reducing conditions, in particular when the landfill leachate contains high levels of phosphate and bicarbonate. The second component of this study entailed evaluating As release mechanisms under highly reduced groundwater con (open full item for complete abstract)
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    Committee: John Lenhart (Advisor); Nicholas Basta (Committee Member); Olli Tuovinen (Committee Member); Brian Lower (Committee Member); Kirk Scheckel (Committee Member) Subjects: Environmental Engineering; Environmental Geology; Environmental Science

  • 15. Langlois, Maureen Using Contaminant Photoreactivity as a Holistic Indicator to Monitor Changes in Wetland Water Characteristics

    Master of Science, The Ohio State University, 2011, Environmental Science

    The light-induced transformation of agricultural products in wetlands is strongly influenced by chromophoric dissolved organic matter (CDOM). Although the absorption of photons directly by contaminant molecules is not a primary transformation pathway in waters such as wetlands, indirect photolysis is a well-studied and important process by which absorbed light causes contaminant transformation in illuminated, aerated waters. The chemical and optical properties of CDOM determine the light absorbance of wetland water and therefore dictate which reactive species will form. In particular, light-induced loss of chromophores (photobleaching) of CDOM generates reactive species according to the concentration and character of chromophoric moieties present. I collected water from four U.S. wetlands: an agricultural wetland in Ohio (YCF), Kawai Nui Marsh in Hawaii (KNM), the Everglades in Florida (EVG), and Okefenokee Swamp in Georgia (OKS). I investigated the photolysis of two broadleaf herbicides, acetochlor (AC) and isoproturon (IP), which have distinct known or suspected predominant indirect photolysis pathways. The purpose of my study was a) to characterize the process of photobleaching in each wetland by monitoring changing optical properties as well as photochemical oxygen consumption during irradiation in a solar simulator; b) to relate photobleaching parameters with contaminant loss in the same waters; and c) to use both of these dynamic properties to assess changes in sampled waters over short (hours) and long (months) timeframes in situ and in storage. Wetland waters samples were split after filtration and half were acidified to investigate the effects of acidification on CDOM. Samples were brought to field pH, spiked with the target herbicides, and irradiated in a solar simulator (Suntest CPS+). Analyte concentrations, UV-vis absorbance and dissolved oxygen (DO) were monitored at intervals throughout the experiment. This procedure was undertaken as soon as possib (open full item for complete abstract)
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    Committee: Linda Weavers (Advisor); Yu-Ping Chin (Advisor); John Lenhart (Committee Member) Subjects: Environmental Science

  • 16. Ziegelgruber, Kate Sediment Pore Water Dissolved Organic Matter in North Dakota (USA) Prairie Wetlands

    Master of Science, The Ohio State University, 2011, Geological Sciences

    Prairie pothole lakes (PPLs) comprise an important part of the hydrology in the upper Midwest. They are highly diverse aquatic ecosystems that are important habitats for migrating waterfowl. They are also in a heavily farmed region and potentially suffer from nonpoint source pollution from agrochemicals. The dissolved organic matter (DOM) in PPL pore waters are presumably highly reduced due to active sulfate reduction in sediments and can potentially be important in the fate and transformation of agricultural pesticides that enter these aquatic systems via nonpoint source runoff. Sediment pore water DOM was quantified by Pt catalyzed high temperature total organic carbon analysis and characterized as a function of sediment depth using high pressure size exclusion chromatography (HPSEC) for molecular weight determination, UV-vis spectroscopy, and fluorescence spectroscopy. Pore water dissolved organic carbon (DOC) concentrations (~61-120 mg C/L) are greater than surface water DOC concentrations (~22-36 mg C/L) and greatly exceed abundances typically reported for wetland pore water samples (10's of mg C/L). The DOM is primarily allochthonous in nature; however autochthonous inputs, especially in samples collected in September, were detected by examining various light absorption spectral parameters i.e., specific UV absorbance at 280nm or (SUVA280) and spectral slope ratio (SR) in addition to fluorophore contributions. This pool of autochthonous organic matter is derived from primary production in the water column during the summer season that is presumably transported to the benthic zone in the fall. Fluorescence excitation emission matrices were examined using Parallel Factor Analysis (PARAFAC) to relatively quantify and identify the fluorophores that comprise the DOM phase. A PARAFAC model was created to model the individual fluorescing components of the pore water DOM. Three “humic-like” components explain ~90% of total sample fluorescence while a single “protein-l (open full item for complete abstract)
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    Committee: Yu-Ping Chin PhD (Advisor); W. Berry Lyons PhD (Committee Co-Chair); James E. Bauer PhD (Committee Member) Subjects: Geological

  • 17. Guerard, Jennifer The Characterization of Dissolved Organic Matter and its Influence on the Photochemical Fate of Antibiotics used in Aquaculture

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

    Antibiotics are a class of pharmaceuticals specifically engineered to kill pathogenic bacteria. In addition to medicinal applications for treating people, antibiotics are also used in a number of agricultural industries to prevent the spread of harmful and costly diseases. However, the increased prevalence of resistant strains of bacteria hasraised concern about the environmental fate of such compounds, particularly once in the natural environment. For many antibiotics, little information is known about their breakdown or fate in natural waters. This work investigated the photochemical transformation of two antibiotics commonly used in aquaculture (catfish), sulfadimethoxine and ormetoprim and the role that dissolved organic matter (DOM) composition plays on the fate of these compounds. Sulfadimethoxine degradation was found to be dependent on DOM source composition, and degraded via triplet excited state pathways. Ormetoprim was found to degrade through indirect pathways that included transformation via two reactive oxygen species(ROS) promoted by DOM - the hydroxyl radical and singlet oxygen. The effects of source on dissolved organic matter composition were studied, and an intensive investigation was performed to characterize the photoreactivity of a fulvic acid isolated from Pony Lake on Cape Royds, Ross Island, Antarctica, a completely microbially-derived DOM end-member.
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    Committee: Yu-Ping Chin PhD (Advisor); Linda Weavers PhD (Committee Member); Christopher Hadad PhD (Committee Member); Diane McKnight PhD (Committee Member) Subjects: Chemistry; Environmental Science

  • 18. Jacobs, Laura Photochemical Transformation of Three Polycyclic Aromatic Hydrocarbons, Ibuprofen, and Caffeine in Natural Waters

    Doctor of Philosophy, The Ohio State University, 2008, Environmental Science

    The photolysis of three polycyclic aromatic hydrocarbons (PAHs), pyrene, phenanthrene, and naphthalene were studied in waters taken from Gary, Indiana (GIN) and Wilmington, North Carolina (WNC). Direct photolysis of PAHs was observed with pyrene degrading at a faster rate than either phenanthrene or naphthalene. When compared to direct photolysis, phenanthrene degradation increased in GIN water, but decreased in the WNC water due to higher levels of dissolved organic carbon (DOC) for WNC (9.29 mg/L vs 6.73 mg/L for GIN) and less nitrate (0.046 mM vs 0.205 mM) for GIN. The slightly lower rate of phenanthrene degradation in WNC water, corrected for light attenuation effects, is statistically the same as the direct photolysis experiments. We attribute the lower rate of degradation in the presence of WNC water to light screening by DOC, while we believe that the faster reaction rate observed for GIN is the result of nitrate generated hydroxyl radical chemistry. Overall photo-reaction rates decrease for the lower molecular weight PAHs as the fastest naphthalene photolytic rate was roughly two orders of magnitude slower than the photolysis of pyrene. The photolysis of ibuprofen and caffeine was studied in solutions of fulvic acid isolated from Pony Lake, Antarctica (PLFA); Suwannee River, GA (SRFA); and Old Woman Creek Natural Estuarine Research Reserve, OH (OWCFA). At 10µM initial concentration ibuprofen and caffeine degrade slowly by direct photolysis, but we observed enhanced photodegradation in solutions of each fulvic acid. Quenching studies suggest hydroxyl radical plays a prominent role in both caffeine and ibuprofen photolysis. Spectroscopic techniques reveal the formation of multiple hydrophobic photo-products upon photolysis of ibuprofen, the dominant byproduct identified as 1-(4-isobutylphenyl)ethanol and a minor derivative isobutylacetophenone. Caffeine and ibuprofen photolysis reactions proceed even more quickly in fulvic acid solutions (6 mg/L DOC) at lower, (open full item for complete abstract)
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    Committee: Yu-Ping Chin PhD (Advisor); Linda Weavers PhD (Advisor); Terry Gustafson PhD (Committee Member); Walker Harold PhD (Committee Member) Subjects: Environmental Science

  • 19. Hakala, Jacqueline Alexandra The abiotic transformation of nitroaromatic pesticides by Fe(II) and dissolved organic matter

    Doctor of Philosophy, The Ohio State University, 2008, Geological Sciences

    Nitroaromatic pesticides are hydrophobic contaminants that can accumulate in sediments by the deposition of suspended solids from surface waters. Fe(II) and dissolved organic matter (DOM), present in suboxic and anoxic zones of freshwater sediments, can transform nitroaromatic pesticides in natural systems. In this study, the abiotic chemical transformation of pentachloronitrobenzene, trifluralin and pendimethalin was studied in controlled laboratory systems containing Fe(II) and fulvic acid DOM isolates, and in natural pore waters collected from a freshwater wetland. Geochemical parameters affecting reactivity in the natural wetland were also monitored. This study is the first to investigate nitroaromatic pesticide reduction in the presence of Fe(II) and DOM surface water isolates, and in natural benthic pore waters that contain high concentrations of dissolved Fe(II) and DOM. Although pentachloronitrobenzene, trifluralin and pendimethalin were reduced both in controlled systems and natural pore waters, reduction in unaltered pore waters was roughly an order of magnitude slower than in systems containing Fe(II) and fulvic acid isolates. These data show that controlled systems over-estimate nitroaromatic pesticide reactivity in natural systems, and also suggest that Fe(II) is naturally complexed to Fe(II)-stabilizing ligands in anoxic environments. Future work is necessary to elucidate the speciation of Fe(II) complexes present in natural anoxic environments.
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    Committee: Yu-Ping Chin (Advisor) Subjects:

  • 20. Kim, Sunghwan Structure and reactivity of dissolved organic matter as determined by ultra-high resulution electrospray ionization mass spectrometry

    Doctor of Philosophy, The Ohio State University, 2003, Chemistry

    There is currently little molecular level information available for dissolved organic matter (DOM). In this study, electrospray ionization mass spectrometry (ESI-MS) with ultra-high resolution has been used to study DOM at a molecular level. High resolution mass spectra of DOM routinely contains several thousand peaks with a multitude of peaks in each nominal mass region. To study the spectra at the molecular level, the individual peaks need to be examined, a process that is arduous and time consuming. In this study, use of the van Krevelen diagram is demonstrated as an innovative graphical interpretation tool for ultra-high resolution mass spectrometric data of DOM. Plotting of ESI-FT ICR-MS data from DOM indicates that lignin or tannin type molecules compose the main portion of readily ionizable DOM molecules. In addition, many peaks corresponding to hydrogen deficient molecules are observed. These hydrogen deficient molecules found in DOM samples can be related to black carbon derived material. The process of consumption and utilization of DOM by microorganisms is investigated by employing plug-flow thin film bioreactors and ultra-high resolution mass spectrometry of DOM from inflow and outflow water samples. It is shown that the DOM molecules are subject to modifications to lower molecular weight molecules by micro-organisms. Applying van Krevelen analyses for mass spectral data reveals that relative importance of the peaks with low H/C ratios (especially the peaks in the region that has been assigned to black carbon molecules) are generally increased from inflow to outflow water samples. This is consistent in two sets of bioreactor samples collected from two different locations. The current study clearly demonstrates that the method employed in a significant “breakthrough” in the ability to recognize such a biologically refractory form of DOM.
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    Committee: Patrick Hatcher (Advisor) Subjects: Chemistry, Analytical
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