▼ Scouting for insect pests is the backbone of all Integrated Pest Management (IPM) programs. The success of IPM programs relies on the insect pest population estimates that scouting methods provide. Scouting methods can reduce the number of pesticide applications by 40 to 60% (Hollingsworth et al., 2000) and pesticide use by 30% (Cloyd et al., 2005). However, most of the scouting methods are unreliable, labor demanding and tedious. Therefore, this research effort recognized the need of the greenhouse industry for a system that is capable of covering a large greenhouse growing area while collecting samples consistently and time efficiently. Two greenhouse scouting methods were selected based on collection efficiency, labor requirements and mechanization feasibility. These methods were the vacuum approach and the sticky card. To allow automatic sampling of insects both scouting methods were prototyped and mounted on an overhead automatic irrigation system. The two prototypes were named: 1) the mobile insect vacuum, and 2) the mobile sticky card. To compare the collection efficiencies of the prototyped mobile methods and a traditional yellow sticky card, greenhouse tests were carried out. Tests were conducted to investigate the effects of two greenhouse air temperatures (13.5 and 28.5°C) and the use of an assisting air jet on the collection of adult whiteflies (Bemisia tabaci) from poinsettia (Euphorbia pulcherrima) cv. Freedom Red canopies. Results from these tests showed that the air assisted mobile insect vacuum had the highest mean collection efficiency (MCE= 3.0 ± 0.5 %). The method was capable of consistently collecting adult whiteflies from poinsettia plants at 13.5 and 28.5°C. Improvements in the air assisted mobile insect vacuum prototype collection efficiency were deemed desirable for more reliable insect detection. To aid in the design process of the proposed insect collection system, analytical and numerical models based on turbulent jet theory and computational fluid dynamics were proposed. These models can be used to assist in the engineering design of the optimum assisting air jet and intake hood of a vacuum based insect sampling system. The system should provide the required airflow to efficiently collect adult whitefly (Bemisia tabaci) from greenhouse poinsettia (Euphorbia pulcherrima) plants without damaging the canopy foliage. The models can be used to: 1) estimate greenhouse crop canopy drag coefficient, 2) predict centerline air velocities in the collection system flow field and 3) compute the geometries of the assisting air jet nozzle outlet and intake hood suction inlet. Model inputs such as the jet momentum (per unit of time) (J =28 Kg-m/s2) and the suction flow (V_t=1.3 m/s) were determined experimentally and analytically, respectively. Wind tunnel and laboratory tests were performed to determine the poinsettia crop canopy drag coefficient (C_D=0.1 ± 0.01) and the suction and the air jet centerline profiles. The numerical model can be use to simulate several assisting air jet intake configurations, study the collection flow characteristics and evaluate critical geometries. The model has the potential to save prototyping time and money. Advisors/Committee Members: Ling, Peter.

▼ Polyphenoloxidase (PPO, EC 1.14.18.1) is one of the major enzymes in fruits and vegetables that causes undesirable browning when it reacts with phenolic substrates in the presence of oxygen to yield dopaquinone and eventually form melanin pigments. In this study, a purified PPO from mushroom was subjected to a constant electric field strength (10 V/cm) at different frequencies (60, 600 and 6000 Hz) at three isothermal conditions (40, 50, 60°C) for 5, 10 and 15 min. To isolate the effect of frequency, samples were also heated conventionally at the same temperature-time history. Enzyme activity was measured using spectrophotometric method and compared with that of untreated samples. Results showed that moderate electric field treatments (MEF) stimulated higher enzyme activity (p<0.05) compared to conventional heating at 60 and 6000 Hz 40°C 10 min, 6000 Hz 40°C 15 min and at all frequencies at 60°C 15 min. Reduced activity (p<0.05) was observed at all frequencies but at different conditions in the first 10 min of 60°C treatments: 60 Hz 5 min as well as 600 and 6000 Hz both at 10 min. The data suggests that MEF activation is likely to occur at higher frequency (6000 Hz) and at longer holding periods (15 min). Both the activation and inactivation results can be useful in medical and food processing applications. Further studies on the isolated effect of frequency treatments on specific enzyme isoforms and oxidized states may clarify the response mechanism of PPO to electric field stimulation. Advisors/Committee Members: Sastry, Sudhir.

▼ Full-scale high solid anaerobic digestion (AD) technology for wastewater treatment and renewable energy production, the first of its kind in the country, was recently installed in the city of Akron, Ohio. Currently, 1/3 (5000 dry tons/yr) of their dewatered municipal sewage sludge (MSS) is stabilized via AD, while the remainder is stabilized by composting. Expansion and sizing of future AD reactors to accommodate additional organics generated by the facility is being considered. To evaluate this option a better understanding of the effects of organics loading rate (OLR) on AD is needed because, there is a lack of information on the effects of increased OLR on reactor performance and stability. The hypothesis of this study was that increasing the OLR from 3.4 to 5.0 gVS L-1d-1 would not affect the biochemical or molecular properties related to reactor stability and performance. To test this hypothesis, a laboratory simulation of the full-scale AD process was conducted in a 42-day study. Six identical continuously stirred-tank mesophilic reactors with 3.5 L working volumes were used. Four different treatments were evaluated, one of which was replicated (treatment 1) to assess error and variability. The first treatment (T1) had an OLR of 3.4 gVS L-1d-1 equal to the current full-scale OLR. Treatment 2 (T2), treatment 3 (T3) and treatment 4 (T4) had OLR of 4.0, 4.5 and 5.0 gVS L-1d-1, respectively. To assess the effects of increased OLR on reactor performance and stability, biochemical and molecular parameters were used. Archaeal community structure dynamics were determined by PCR amplification of 16S rRNA genes using fluorescently labeled archaeal primers (Ar109f and FAM labeled Ar912rt) followed by terminal restriction fragment polymorphism (T-RFLP) analyses using TaqI, AluI and BfaI restriction enzymes. Results showed that reactors maintained stable conditions during the experimental period. An increase in the amount of organic matter biodegradation was observed with increasing the OLR, resulting in higher organic matter removal and volumetric methane production rate. The highest VS removal and volumetric methane production results were observed for T4, 54 ± 2% and 1.4 ± 0.1 LCH4 L-1d-1, respectively. Moreover, the efficiency of reactor conversion of organic matter to methane was found to be similar in all the treatments with an average value of 0.57 ± 0.07 LCH4 gVS-1removed. The archaeal TRFs derived from the three endonucleases used for molecular analysis, showed that predominant TRFs remained stable during the experiment accounting for an average relative abundance (RA) of 81 ± 1%. The TRFs with the greatest abundance using TaqI, AluI and BfaI respectively had sizes of 185, 166 and 104 base pairs, respectively. Archaea consistent with combinations of the three sets of TRFs included members of both the Euryarchaeota and Crenarchaeota phyla, including acetoclastic metabolic groups which utilize acetate to produce CH4 and hydrogenotrophs, which utilize hydrogen as an electron acceptor to produce CH4. Orders of Euryarchaeota consistent with the TRFs were Methanomicrobiales, Methanosarcinales and Methanobacteriales. The TRF combination that was consistent with the Crenarchaeota phylum, belonged to an uncultured Crenarchaeote. In conclusion, this laboratory-scale study suggests that performance and stability as well as the archaeal community structure in this digester system was unaffected by increasing the OLR by nearly 50%. Furthermore, increasing the OLR increased the amount of methane gas generated from the same size reactor. Advisors/Committee Members: Michel Jr., Frederick C.

▼ In the U.S. the national goal is to eliminate the discharge of pollutants into waterways. Onsite soil based wastewater treatment and irrigation of treated wastewater are two ways to meet this goal. In Ohio, approximately 49 % of the total land area is too shallow, relative to limiting conditions, to provide complete sewage treatment, but is deep enough to accept reclaimed wastewater by spray irrigation. However, year-round dispersal of wastewater effluent is hindered by winter sub-freezing air temperatures that cause spray irrigation system to freeze and the accumulation of snow that may bury the irrigation system.To investigate the freezing problem, three different models of revolving rotor sprinklers (Rainbird 5000-s, Toro s-800 and Hunter-PGC) and one model of revolving impact sprinkler (Rainbird 2045-pj) were tested at -25°C in a laboratory setting, with water at 24°C. The sprinklers were drained at the end of each irrigation event. The heads sprayed water properly, but they exhibited rotational delay ranging from 4 to 10 minutes. Mann-Whitney tests showed that the Rainbird sprinklers had shorter rotational delay. The rotational delay was not eliminated by the irrigation of water at temperature varying from 28 to 40°C. A Mann-Whitney test showed that the rotational delay of Rainbird 5000-s decreased by one minute when the temperature of water changed from 28 to 32°C. The rotational delay may cause overall low distribution uniformity. The snow depth was investigated where Hi-pop up irrigation sprinklers may be used all year-round to disperse reclaimed wastewater in Ohio. Maximum depths of snow cover over thirty to forty eight years at two hundred and fifty three stations in Ohio and in adjacent states were used in a geostatistical interpolation operation. A triangulated irregular network interpolation method was used to predict and represent the maximum depth of the snow cover in the different regions of the state. The study revealed that snow cover may reach a minimum of 12 in. in all counties in Ohio during the months of January and February, at least once every thirty to fifty years. The drainage of sprinkler and riser at the end of irrigation events is a potential means to prevent systems from freezing; but it does not assure that the system will provide proper distribution uniformity, which may lead to reclaimed wastewater pounding and runoff. Using Hi-pop up sprinklers for year-round application of reclaimed wastewater poses the risks of the system being covered by snow. An alternative would be to use shrub rotor irrigation sprinklers mounted on risers. Advisors/Committee Members: Mancl, Karen.

▼ The two goals of this thesis were to 1) explore methods for developing relationships between discharge and recurrence interval, and predicting flow exceedances - particularly for high frequency recurrence intervals 2) Address site-specific bankfull properties to explore methods to determine whether the proper bankfull elevations are selected. Methods for the first goal of determining recurrence intervals discharges include three temporal data resolutions and three statistical methods. A calibration method was used related regression peak discharge equations to gage discharges and apply the index method to predict discharges at ungaged sites that were examined. A flow duration curve was developed to determine discharge exceedances. Results for goal one revealed that all three statistical methods provided similar 2 to 5-year discharges; however, the tails of the distribution (1-year and 100-years) were different due to the type of statistical method selected and is not uncommon for discharge data with large periods of record. Results for expected recurrence intervals at bankfull discharge corresponds to 25-50% of the 2-year discharge. Flow exceedances determined that the higher frequency discharges had a wide range of flow exceedances with the 0.2-year discharge exceedance values varying from 50 to 170 times per year and the 1-year discharges varying from 1to 13 days per year. Methods used for goal two included a full geomorphic surveyed data completed for all 17 study locations in central Ohio used in goal one. Bankfull channel dimensions were analyzed to regional curves and then grouped based on a threshold of bankfull width. A logistic regression was performed which was used to determine whether sites were properly grouped by bankfull features. Results for goal two provided a quantitative guideline to identify when modification of a ditch to two-stage geometry might establish bankfull dimensions that are consistent with the studied regional curve for ditches in central Ohio. This study also indicated that selection and application of a regional curve may not always establish the expected bankfull dimensions. Advisors/Committee Members: Ward, Dr. Andrew.

▼ Three investigations were conducted on small-scale digesters in Costa Rica to optimize their ability to treat animal wastewater and produce renewable energy. The first study investigated variability in biogas quality and water pollutant reductions in seven digesters located at small-scale farms in Costa Rica. The second study investigated the production of electricity using combined biogas from swine and dairy digesters. The final study investigated increases in biogas production by co-digesting swine manure and used cooking grease in 12 field-scale digesters. This study assessed methane production, wastewater pollutant reductions, and fertilizer utility.The digester variability study revealed that the digesters maintain high reductions in organic matter (84.1 %), produce biogas with a high percentage of methane (66.3 %), and produce a fertilizer that has 78.3 % more NH4-N. In the electricity production study, the dairy and swine digesters produced 27.5 and 6.0 m3/day of biogas, with 62.6 and 76.4 % methane, respectively, and reduced organic matter by 86.1 and 91.9 %, respectively. Eighty-two percent of the farm’s 2-hour peak electricity demand (25.8 kW/day) was met. The $21,000 capital cost of the digester project will be recovered in 10 years through electricity savings and reductions in wastewater fines. If the generator were more appropriately sized for the farm, the capital recovery time would have been 7.6 years. Co-digestion experiments were conducted on 12 field-scale digesters using three replications of four treatment groups: the control (0%) and 2.5, 5, and 10 % used cooking grease (by volume) combined with swine manure. The 2.5 % treatment increased the methane production by 111%. No additional benefits were seen by increasing the grease concentration beyond 2.5 % due to the lower quality of biogas produced. No adverse effects were observed from co-digesting with 2.5 % grease in terms of organic matter removal, pathogen reduction, and grease removal. There was less phosphorus reduction with co-digestion, resulting in lower N:P ratios in the grease treatment groups. These investigations proved that small-scale digesters are ideal systems for rural farmers to treat livestock wastewater and obtain renewable energy from their waste products. The digesters provide energy, which results in the elimination of firewood collection or propane purchase for cooking, improve the water quality of the effluent, and produce a liquid fertilizer. In addition, these systems are cost-effective and require little maintenance. The technology should be spread to other rural farmers in tropical areas. Larger installations can be used for electricity production, and mixing different types of manure can increase electricity output. Adding grease to the influent is a simple way that energy production can be doubled without affecting other digester benefits. Advisors/Committee Members: Martin, Jay.

▼ Leading Dutch researchers reported significant benefits to closed greenhouse systems. Ooteghem (2007) simulation studies of optimal control in a closed greenhouse environment predicted 52% heating fuel saving and 39% increase of tomato crop yield using a heat recovery system whose major components included heat pumps, heat exchangers and aquifers. Opdam et al. (2005) reported 19% primary energy saving, 22% yield increase, 80% chemical reduction, and 50% irrigation water saving for tomato production in a closed greenhouse. Although the Dutch researchers successfully demonstrate year-round operation of closed greenhouses, their success benefited from the mild weather and availability of aquifers, not always the case for other geographical regions. Results of this study using Ohio conditions estimated that 90% and 92% of CO2 loss through cooling and dehumidification ventilations when an elevated CO2 level of 800 ppm must be maintained. This study also found that for Wooster, Ohio to achieve economical year-round closure, due to the larger weather variation and lack of accessibility to aquifers, a better economical return would be expected with semi-closed designs that allow the greenhouse to vent when the heat load is approaching a certain percent of peak levels. For example, a 50% peak load design can meet the cooling and dehumidification needs of a closed greenhouse for 92% and 90% of the year, respectively. Also determined in this study was the amount of heat which can be recovered with thermal storage. Potential recoverable heat of a closed greenhouse at Wooster, Ohio can contribute up to 23%, 25% and 98% of total heating needs of the year, 2006, with 1-day, 2-day and year-round thermal storage capacities, respectively. The models used for the above analyses were evaluated using data collected in a greenhouse located at Wooster, OH. Convection and infiltration heat loss prediction were validated during cloudy and clear sky nights. The results gave prediction disagreements of 0.2% to 2% and 30% under cloudy and clear sky conditions, respectively. Also evaluated was the potential recoverable heat from ventilation exhaust. Result showed that ventilation time prediction disagreement were -8.2% and 0.8%, when net solar radiation transmittances were estimated at 0.54 and 0.57, respectively. Although further improvements of this model could be done, the data processing framework established for the heat recovery strategy evaluation is valuable for the assessment of potential benefits of semi-closed greenhouse. Advisors/Committee Members: Ling, Peter P.

▼ Biomaterials involving life, could be bio-derived or bio-inspired and have properties and characteristics that are quite complex to be adequately synthesized and analyzed by deterministic methods. Probabilistic modeling tools provide necessary insights and understanding of mechanisms and processes induced and/or integrated in them for purposes of applications in biology, medicine and engineering. The hypothetical additive and synergistic effects potentiated by the common cellular targeting of the microtubule stabilization are eroded depending on the heat delivery temperature, Paclitaxel nanoparticles (Taxol) concentration and sequence of application. The purpose of the study was to provide better predictive understanding of the effects of hyperthermia (41° to 45° C), Paclitaxel nanoparticles (Taxol) and their synergistic combination on the growth and shrinkage of MDA-MB-231 cells. As an application of the study, characterization of the temperature pattern distribution from the recently fabricated implantable hyperthermia device was achieved in a monolayer of these cells. Overall, the more nonlinear exponentiated polynomial quotient response Z (QRZ)-models with degree (K+1) contextually modeled the phenomenon of hyperthermia (physically illustrated by use of Isohypethermals) and the live cell count response to Taxol in both early and late cell generations. The mixed log-normal and exponential multiparameter QRZ-model effectively predicted the peripheral temperature developed by the newly fabricated implantable hyperthermia Microdevice. The model predictive power and the unit change effects of the drug concentration and exposure times based on the developed QRZ-model were best characterized using chemographs. The study provided improved understanding of the effect of combined hyperthermia (41o to 45o C) and Paclitaxel nanoparticles from a quantitative point of view. Temperatures below 43 °C did not adequately inhibit growth of the most invasive MDA-MB-231 cell line. Contrastingly, growth of cancer cells was completely inhibited by temperatures at and above 43 °C. It has been demonstrated for the first time by use of Isochemotherapy curves the existence of the minimum critical hyperthermic temperature (MCHT) of 43°C. This finding gives the potential temperature for the synergistic outcome of simultaneous application of both hyperthermia and Taxol in treatment of breast cancer. Depending on the temperature regime for the combinational therapy either below 43°C or at and above 43°C, drug diffusion or heat transfer and diffusion becomes dominant cell-killing agent, respectively. Advisors/Committee Members: Soboyejo, Alfred B.O.

▼ In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The objectives of this study were to: 1) test the possibility of generating electricity in an MFC with rumen microorganisms as biocatalysts and cellulose as the electron donor, 2) analyze the composition of bacterial communities enriched in cellulose-fed MFCs, 3) determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs, 4) evaluate bacterial diversity and cellulose metabolism under different circuit loads, 5) assess the influence of methane formation on the performance of cellulose-fed MFCs under long-term operation, and 6) characterize the diversity of methanogens in cellulose-fed MFCs. The results demonstrate that electricity can be generated from cellulose by exploiting rumen microorganisms as biocatalysts. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. abounded in the suspended consortia. Results suggest that oxidation of metabolites with the anode as an electron sink was a rate limiting step in the conversion of cellulose to electricity in MFCs. This study also shows that the size of external resistance significantly affects the bacterial diversity and power output of MFCs. A maximum power density of 66 mW/m2 was achieved by the 20-ohm MFCs, while MFCs with 249, 480 and1000 ohms external resistances produced 57.5, 53 and 47 mW/m2, respectively. Thus the external resistance may be a useful tool to control microbial communities and consequently enhance performance of MFCs. Furthermore, this study demonstrates that methanogenesis competes with electricity generation at the early stages of MFC operation but operating conditions suppress methanogenic activity over time. The suppression of methanogenesis was accompanied by a decrease in the diversity of methanogens and changes in the concentration of short chain fatty acids. An improved understanding of the microbial communities, interspecies interactions and processes involved in electricity generation is essential to effectively design and control cellulose-fed MFCs for enhanced performance. In addition, technical and biological optimization is needed to maximize power output of these systems. Advisors/Committee Members: Christy, Ann.

▼ I developed an ecological-economic model representing the Sandusky region of Lake Erie to explore the relationship between internal ecosystem change and management of external phosphorus loading. The model was comprised of two sub-models: an ecological unit model and a phosphorus management model reflecting the societal benefits and costs of phosphorus regulation. These two sub-models formed a dynamic feedback loop including freshwater ecology, ecosystem services, and phosphorus management. Climatic fluctuations in phosphorus loading caused significant variations in the quality of ecosystem services between years. Decreases in ecosystem resistance to eutrophication caused by dreissenid mussels created multiple stable states of management compromise. Adaptive management benefited ecosystem services during mussel invasion scenarios, while unresponsive management was biased towards groups discharging phosphorus. Large-scale wetland restoration shifted management compromise to states characterized by less on-site management and higher environmental quality. The perturbation-based approach taken here illustrates that equilibrium in ecological-economic systems over time is unlikely. Advisors/Committee Members: Martin, Jay.

▼ Composting offers the potential to significantly reduce problems associated with manure management including odors, pathogens, ground water pollution, and utilization costs. Two variables that directly affect on-farm composting costs are windrow size and windrow turning frequency. However the size of a windrow is limited by the depth of penetration of oxygen and high temperatures as well as available equipment. In this study three full scale compost sets were set-up at the Ohio Agricultural Research and Developing Center (OARDC) compost pad to evaluate the effects of turning frequency, pile size and seasonal variability on physical (temperature, oxygen, bulk density, moisture and weigh loss), chemical (volatile solid loss, pH, Carbon and Nitrogen concentrations) and biological (plant growth bioassays and microbial community structure) parameters during dairy manure/sawdust composting (DM+S). Based on these data the operational costs for producing and transporting compost were estimated and compared to those for liquid manure and fertilizer. The three treatments consisted of a set of windrows (A) which were turned using a self propelled and tractor drawn windrow turner every three days for a total of 32 turns during 16 weeks, a second set (B) that was turned once every ten days and a third set (C) consisting of much larger piles turned that was also turned every ten days with a loader. All three sets were composted in both winter and summer for 120 days. The hypotheses of the study was that; turning frequency, pile size and season do not significantly affect compost process parameters or the final chemical, physical or biological properties of cured composts. Results showed that neither physical chemical nor biological properties of the final cured composts were significantly affected by turning frequency, season or pile size (p > 0.05). During composting, he the surface area, oxygen concentrations and Total nitrogen losses were significantly affected by pile size (p < 0.05). Turning frequency affected (p < 0.05) mass losses, bulk density and total nitrogen losses. The seasonal effects on composting during the process were primarily related to moisture (p < 0.05), mostly due to ambient temperatures which affects water holding capacity of air. Despite these process differences, the final cured composts from all treatments and seasons had similar properties (p > 0.5). Plant growth bioassays showed a high emergence percentage (> 80%). The fertilized cucumber plants grown in composts from the various treatments in summer had higher shoot dry weights than peat controls (≥ 100%) except for day 30 in pile C (89%). The unfertilized cucumbers plants showed an increase of shoot dry weight at the end of the composting process (day 120) except for windrow A in summer. However the bioassay tests were inconclusive. Microbial Community analysis, based on Terminal Restriction Fragment Length Polymorphisms (T-RFLP), showed that management differences (turning frequency, pile size and season) did not significantly affect (p > 0.05) microbial community structure. Clustering, pairwise comparison, principal component analysis (PCA) and Kruskal Wallis tests were used to determine the similarities and differences between microbial communities in the different treatments. In each treatment a different subset of TRFs were present suggesting that different classes of organisms predominate during different stages of composting.. However, one terminal restriction fragment H371 contributed significantly (p < 0.1) to the observed variation as a function of compost age. The Restriction Fragment (TRF) sizes obtained in the different treatments were compared to fragment sizes predicted by in silico amplification and digestion (RDP v.9.0) to characterize the microbial community in the composts. TRFs fragments sizes were also compared to a clone library of 263 sequences from composted dairy manure. Representative TRFs (61, 93, 99, 159, 167, 205, 215, 227, 365, 373, 437 and 481) in the compost samples were consistent with the predicted TRFs of Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria. The main factor affecting total compost production operational cost was the cost of the bulking agent. Operational costs for frequently turned windrow were higher ($109/Mg) compared to the infrequently turned windrow ($95/Mg), and the infrequently turned piles ($93/Mg). These differences are due to the time that is needed to turn and the equipment fuel costs. Thus, infrequent turning (every ten days) with larger windrow sizes reduced the operating costs associated with unseparated dairy manure composting compared to more frequently turning windrows. It is recommended for the farmers to use a turning frequency of ten days and piles with a surface to volume ratio of 0.9-1.2 m2/m3 to minimize operational costs. If composting is performed in temperate climates there is a need to consider the moisture content at the beginning of the process to prevent moisture irregularities during the process. Advisors/Committee Members: Michel, Frederick.

Advisors/Committee Members: Sastry, Sudhir K.

▼ Stormwater inputs increase pathogen concentrations in rivers. Current strategies to prevent pathogen inputs to rivers are often ineffective. Researchers propose enhancing the self-purification capacity of rivers in Ohio with riparian wetlands. This study asked: 1) Do urban riparian wetlands in central Ohio reduce pathogens? 2) What variables are associated with pathogen reduction? 3) Does water discharging from urban riparian wetlands meet Ohio EPA regulations? To answer these questions, this study monitored Escherichia coli and other water quality variables in two 1-ha urban riparian wetlands at the Olentangy River Wetland Research Park in Columbus, Ohio for ten months. This study found 1) 17% total E. coli reduction through the wetlands, with the wetlands most effective when needed most, i.e., when inflow concentrations increased due to stormwater; 2) pathogen reduction was associated with turbidity reduction; and 3) water discharging from the study wetlands met Ohio EPA standards 100% of the time. Advisors/Committee Members: Martin, Jay.

▼ Turfgrass systems require large inputs of fertilizers and pesticides that can impact surface water, ground water, and soil quality. Water quality and hydrologic data were collected at Morris Williams Municipal Golf Course in Austin, Texas, between 1998 and 2003. The data were analyzed, illustrating the application of time series analysis to hydrological data sets. Time series analyses were used to assess the dependence of nutrient concentrations in drainage and surface water on climate and management factors. The analysis of nutrient loads in drainage water and runoff from the site indicated that nitrate-N posed no significant threat to ground or surface water. Dissolved reactive phosphorus (DRP) concentrations in ground water were higher than values recorded for locations planted with agricultural crops. In-stream attenuation of DRP occurred, but there was still a net contribution of DRP to surface water. Management strategies to reduce DRP concentrations may be needed to protect surface and ground waters from the intensive application of fertilizers in turfgrass systems. Calibration and validation of a modified SWAT model (SWAT-TGER) was conducted using runoff data collected from the study site. The model generally underestimated the volume of runoff for most rainfall events, especially small volume events. The SWAT-TGER predictions were not significantly different (p=0.05) from measured values when fewer than 5 days had elapsed between rain events and either the intensity was greater than 5 mm in 15 minutes or the rainfall event was greater than 30mm. It also overestimated the concentrations of nitrate-N in the runoff from the site. Runoff estimation efficiency (E = 0.65 to 0.73) and nitrate-N estimation efficiencies were, however, within values reported in the literature for similar studies. SWAT currently incorporates the curve number method in its simulation of runoff. The data from this site demonstrate that for some watersheds, the curve number's traditional definition of the initial abstraction value (0.2S) may not be appropriate. After testing a range of values, it was found that using an initial abstraction of 0.05S resulted in more accurate runoff predictions. Incorporating this method into SWAT may allow better simulation of runoff without the necessity of elevating curve numbers. Advisors/Committee Members: Christy, Ann.