Browsing by Subject "water quality"
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Item A New Method to Assess Best Management Practice Efficiency to Optimize Storm Water Management(2014-12-16) Tu, Min-chengFor TSS, TN, and TP, this study examined the relationship between BMP pollutant removal efficiency and environmental factors such as ratio of BMP/catchment area, dominant land use, ratio of the dominant land use/catchment area, slope, and BMP type, and derived optimal installation plans based on different criteria. A SWMM model was built for the Shoal Creek Watershed in Austin, Texas. Inverse modeling (i.e. fitting model to observation data) was used to calibrate the BMP removal efficiency. The relationship can then be derived by using multiple linear regression analysis with BMP removal efficiency as the response variable and the environmental factors as predictive variables. However, before inverse modeling can be applied, SWMM pollutant buildup and washoff parameters must be derived. A few types of land use were identified as main source of pollutant. The numerical distribution of the parameters suggested that the buildup and the washoff parameters are controlled by forces of different spatial scales. Also, the SWMM model simulated only direct runoff in order to simplify the calibration. Mean pollutant concentration in base flow is required to convert observed concentration to that in direct runoff. The Shoal Creek Watershed discharges into Lady Bird Lake, and changes of water quality in the lake during base flow dominant dates were used to estimate concentration in base flow from Shoal Creek Watershed. Water quality of the lake was determined by Landsat imagery. The equations predicting BMP removal efficiency based on environmental factors were analyzed to show the most efficient and least efficient type of BMP and the land use that BMPs will have the highest and lowest removal efficiency for TSS, TN, and TP. Two planning criteria were utilized for the optimal BMP plans and different time frames were considered. One criterion is goal concentrations in runoff, and the other is a combination of goal concentration and a budget constraint. For each criterion, the associated optimal plan showed an areal ratio between BMP types throughout different time frame. It was also found that the Shoal Creek Watershed needs more BMPs. Suggestions to the Environmental Criteria Manual of Austin were also made based on this study.Item Application of a spatially referenced water quality model to predict E. coli flux in two Texas river basins(2009-05-15) , DeeptiWater quality models are applied to assess the various processes affecting the concentrations of contaminants in a watershed. SPAtially Referenced Regression On Watershed attributes (SPARROW) is a nonlinear regression based approach to predict the fate and transport of contaminants in river basins. In this research SPARROW was applied to the Guadalupe and San Antonio River Basins of Texas to assess E. coli contamination. Since SPARROW relies on the measured records of concentrations of contaminants collected at monitoring stations for the prediction, the effect of the locations and selections of the monitoring stations was analyzed. The results of SPARROW application were studied in detail to evaluate the contribution from the statistically significant sources. For verification of SPARROW application, results were compared to 303 (d) list of Clean Water Act, 2000. Further, a methodology to maintain the monitoring records of the highly contaminated areas in the watersheds was explored with the application of the genetic algorithm. In this study, the importance of the available scale and details of explanatory variables (sources, land-water delivery and reservoir/ stream attenuation factors) in predicting the water quality processes were also analyzed. The effect of uncertainty in the monitored records on SPARROW application was discussed. The application of SPARROW and genetic algorithm were explored to design a monitoring network for the study area. The results of this study show that SPARROW model can be used successfully to predict the pathogen contamination of rivers. Also, SPARROW can be applied to design the monitoring network for the basins.Item Arbuscular mycorrhizal fungi enhance tolerance to bicarbonate in Rosa multiflora cv. burr(Texas A&M University, 2005-11-01) Cartmill, Andrew DavidHigh bicarbonate (HCO3-) content and associated high pH of irrigation water is detrimental to plant growth. Sustain ableagricultural/horticultural production will increasingly have to rely on economically feasible and environmentally sound solutions to the problems associated with high levels of HCO3- in irrigation water. The ability of a mixed Glomus Tulasne & Tulasne species inoculum of arbuscular mycorrhizal fungi (AMF), Glomus ZAC-19 (containing Glomus albidum Walker & Rhodes, Glomus claroideum Schenck & Smith, and Glomus diaphanum Morton & Walker), to enhance plant tolerance to HCO3- was tested on the growth and nutrient uptake of Rosa multiflora Thunb. ex J. Murr. cv. Burr (rose). Arbuscular mycorrhizal colonized and non-inoculated (non-AMF) R. multiflora cv. Burr were treated with 0, 2.5, 5, and 10 mM HCO3-. Increasing HCO3- concentration and associated high pH reduced R. multiflora cv. Burr growth, nutrient uptake, and acid phosphatase activity (ACP), while increasing alkaline phosphatase activity (ALP). Inoculation with AMF enhanced plant tolerance to HCO3- as indicated by greater growth, nutrient uptake, leaf chlorophyll content, higher mycorrhizal inoculation effect (MIE), lower root iron reductase activity, and generally lower soluble and wall-bound ALP activity. While AMF colonization (arbuscules, vesicles, and hyphae formation) was reduced by increasing HCO3- concentration, colonization still occurred at high HCO3- concentration. At 2.5 mM HCO3-, AMF plant growth was comparable to plants at 0 mM HCO3-, further indicating the beneficial effect of AMF for alleviation of HCO3- plant stress.Item Bacterial total maximum daily load (TMDL): development and evaluation of a new classification scheme for impaired waterbodies of Texas(Texas A&M University, 2005-02-17) Paul, SabuUnder the Clean Water Act (CWA) program the Texas Commission on Environmental Quality (TCEQ) listed 110 stream segments with pathogenic bacteria impairment in 2000. The current study was conducted to characterize the watersheds associated with the impaired waterbodies. The main characteristics considered for the classification of waterbodies were designated use of the waterbody, land use distribution, density of stream network, average distance of a land of a particular use to the closest stream, household population, density of on-site sewage facilities (OSSF), bacterial loading due to the presence of different types of farm animals and wildlife, and average climatic conditions. The availability of observed in-stream fecal coliform bacteria concentration data was evaluated to obtain subgroups of data-rich and data-poor watersheds within a group. The climatic data and observed in-stream fecal coliform bacteria concentrations were analyzed to find out seasonal variability of the water quality. The watershed characteristics were analyzed using the multivariate statistical analysis techniques such as factor analysis/principal component analysis, cluster analysis, and discriminant analysis. Six groups of watersheds were formed as result of the statistical analysis. The main factors that differentiate the clusters were found to be bacterial contribution from farm animals and wildlife, density of OSSF, density of households connected to public sewers, and the land use distribution. Two watersheds were selected each from two groups of watersheds. Hydrological Simulation Program-FORTRAN (HSPF) model was calibrated for one watershed within each group and tested for the other watershed in the same group to study the similarity in the parameter sets due to the similarity in watershed characteristics. The study showed that the watersheds within a given cluster formed during the multivariate statistical analysis showed similar watershed characteristics and yielded similar model results for similar model input parameters. The effect of parameter uncertainty on the in-stream bacterial concentration predictions by HSPF was evaluated for the watershed of Salado Creek, in Bexar County. The parameters that control the HSPF model hydrology contributed the most variance in the in-stream fecal coliform bacterial concentrations corresponding to a simulation period between 1 January 1995 and 31 December 2000.Item Characterization of a Karst Coastal Ecosystem in the Mexican Caribbean: Assessing the Influence of Coastal Hydrodynamics and Submerged Groundwater Discharges on Seagrass(2012-07-16) Medina, IsraelBahia de la Ascension (BA) is a pristine, shallow, karst bay located in the Mexican Caribbean, a region experiencing rapid population growth stimulated by intense tourism development. The overall objective of this study was to address the natural hydrographic variability of this inherently vulnerable ecosystem and assess its influence on a key habitat, the seagrass. The chapters follow the three-branched nature of the study which tackled the connected ecosystem issues of coastal hydrology, physical dynamics of flow and circulation, and the ecological dynamics of the seagrass species Thalassia testudinum in BA. Freshwater input to BA is primarily by submerged groundwater discharges and surface runoff; both sources are derived from fissures in the aquifer but feature distinct water quality due to the interaction with adjacent wetlands. Hurricanes explain 36 percent of the interannual precipitation variability in the region. The water balance indicates a persistent net outflow from BA to the adjacent shelf, suggesting an intense exchange across inlets. Both diurnal and semidiurnal tidal frequencies are attenuated in the inner bay, where a meteorologically-induced subtidal water level increase may occur during four-day southeasterly winds. A clear SW-NE salinity gradient was established during dry and rainy seasons, with a strong tidally-driven marine influence throughout the central basin, and a perennial mesohaline ambient in the southwestern-most bay, where hydrodynamics are primarily controlled by wind stress. Thalassia testudinum is the dominant seagrass species in BA, occupying ~90 percent of the substrate, including the freshwater-influenced inner bay. High nutrient inputs, including phosphorus which might have limiting effects in karst environments, along with the wind-driven circulation controlling water residence times are associated with the successful development of T. testudinum (up to 1,461.23 g DW m-2) within the SW bay. Farthest into the central basin, Thalassia consistently exhibited an inverse correlation between abundance and density of shoots. This pattern was enhanced under exceptional precipitation and inputs of denuded organic matter resulting from hurricanes making landfall on this region. The relationship between nutrient distribution and the above/belowground ratio suggested that Thalassia growing in BA favors the development of the aerial component as nutrients availability increases. This study provides a basic understanding of the most important processes molding the patterns of variability exhibited by T. testudinum in Bahia de la Ascension. The salinity gradient and external nutrient supply, along with the hydrodynamic component, define the spatial scale at which the connectivity between the adjacent wetland, the bay, and the shelf may occur.Item Contour Ripping and Composted Dairy Manure for Erosion Control on Fort Hood Military Installation, Texas(2010-07-14) Prcin, Lisa J.Training activities on the Fort Hood Military Installation have imposed serious impacts to its grass-dominated landscape. Six decades of tracked vehicle impacts have caused soil compaction and vegetation reduction which has lead to severe surface erosion. This investigation examined two conservation practices directed at improving and creating sustainable training conditions on Fort Hood training lands, contour ripping and the application of composted dairy manure. The application of composted dairy manure may increase vegetation, while contour ripping may decrease discharge, both of which will lead to a decrease in erosion. Three small 0.30 ha watersheds were established on Fort Hood in January 2005. Each watershed had 0.46 m berms installed on all four sides with a 0.305 m H-flume and was equipped with automated storm sampling equipment. Soil samples were collected prior to any treatments, and twice after compost applications. Discharge and precipitation was collected continuously on each watershed. Stormwater samples were collected during storm events and analyzed for water quality parameters. Water quality samples, discharge and precipitation records were collected between January 2005 and July 2007. Three composted dairy manure application rates at 0, 28 and 57 m3 ha-1 were applied on watersheds C0, C1 and C2, respectively; watersheds were evaluated for effects on NO3 and soluble reactive phosphates (SRP) concentrations and loadings in storm events and on stormwater discharge. Twenty two months after the initial compost application, the two previously composted watersheds (C1 and C2) were treated with contour ripping and C2 received a second compost application. The compost application caused the spikes in NO3 and SRP concentrations and loads immediately after application. Both NO3 and SRP concentrations decreased as the number of days from application increased. Compost application did not appear to have an effect on the discharge from watersheds. Contour ripping had a significant effect on stormwater discharge. Contour ripping decreased discharge by 74 and 80% on C1 and C2, respectively when compared to the untreated control (C0).Item Delineating controls on hydrologic variability and water geochemistry in central Texas(2013-08) Wong, Corinne I; Banner, Jay L.There is a strong concern about how water resources will be affected by future climate change. Investigation of how a hydrologic system might respond to climate change, however, requires a detailed understanding of the controls on and factors that might affect that system. The research presented in this dissertation focuses on improving the understanding of the Barton Springs segment of the Edwards aquifer in central Texas. The first three chapters of this dissertation present research investigating spatial and temporal controls on groundwater geochemistry. The fourth chapter focuses on characterizing and understanding the controls on long-term hydrologic variability by reconstructing past climate from a speleothem (cave mineral deposit) collected from a central Texas cave. On spatial scales, Edwards aquifer groundwater geochemistry is influenced by water-rock interaction (calcite and dolomite recrystallization, gypsum dissolution, and calcite precipitation) and mixing between fresh groundwater and saline groundwater. On temporal scales, variation in groundwater geochemistry is dictated by the extent to which fresh groundwater mixes with recharging stream water. The degree of mixing is sensitive to changes in climate conditions (i.e., more mixing under wetter conditions) and type of flow path (i.e., conduit or diffuse) that dominantly supplies a given site. The geochemistry of stream water, which provides the majority of recharge to the aquifer, is degrading over time and indirectly controlled by anthropogenic sources under both wet and dry conditions. Climate reconstructed from a speleothem suggests that central Texas moisture conditions were relatively constant from the mid to late Holocene (0 to 7 ka), except for an extended dry interval from 0.5 to 1.5 ka. Speleothem δ18O values spike during this dry interval, suggesting that decreases in Pacific-derived moisture or decreased tropical storm activity might have been coincident with the prolonged dry interval. This research has improved understanding of the natural variability of and controls on physical and geochemical components of hydrologic system in central Texas.Item Development and application of the spatially explicit load enrichment calculation tool (select) to determine potential E. coli loads in watersheds(2009-05-15) Riebschleager, Kendra JeanAccording to the USEPA National Section 303(d) List Fact Sheet, bacterial pathogens are the leading cause of water quality impairments in Texas. The automated Spatially Explicit Load Enrichment Calculation Tool (SELECT) uses spatially variable factors such as land use, soil condition, and distance to streams to characterize pathogen sources across a watershed. The results support development of Total Maximum Daily Loads (TMDLs) where bacterial contamination is of concern. SELECT calculates potential E. coli loads by distributing the contributing source populations across suitable habitats, applying a fecal production rate, and then aggregating the potential load to the subwatersheds. SELECT provides a Graphical User Interface (GUI), developed in Visual Basic for Applications (VBA) within ArcGIS 9.X, where project parameters can be adjusted for various pollutant loading scenarios. A new approach for characterizing E. coli loads resulting from on-site wastewater treatment systems (OWTSs) was incorporated into the SELECT methodology. The pollutant connectivity factor (PCF) module was created to identify areas potentially contributing E. coli loads to waterbodies during runoff events by weighting the influence of potential loading, runoff potential, and travel distance. Simulation results indicate livestock and wildlife are potentially contributing large amounts of E. coli in the Lake Granbury Watershed in areas where these contributing sources are not currently monitored for E. coli. The bacterial water quality violations near Lake Granbury are most likely the result of malfunctioning OWTSs and pet waste in the runoff. The automated SELECT was verified by characterizing the potential E. coli loading in the Plum Creek Watershed and comparing to results from a prior study (Teague, 2007). The E. coli potential load for the watershed was lower than the previous study due to major differences in assumptions. Comparing the average ranked PCF estimated by physical properties of the watershed with the statistical clustering of watershed characteristics provided similar groupings. SELECT supports the need to evaluate each contributing source separately to effectively allocate site specific best management practices (BMPs). This approach can be used as a screening step for determining areas where detailed investigation is merited. SELECT in conjunction with PCF and clustering analysis can assist decision makers develop Watershed Protection Plans (WPPs) and determine TMDLs.Item Development of an ArcGIS-pollutant load application (PLOAD) tool(2009-06-02) Young, De'Etra JenraMany of the findings of previous studies have indicated that there is a direct correlation between water quality and urbanization. Increasing impervious coverage typically results in a decrease in water quality. The purpose of this study was to adapt an automated tool for assessing the Pollutant Load Application (PLOAD). Created by CH2M HILL, a fullservice engineering and construction enterprise, PLOAD is a simplified GIS-based model used to calculate pollutants within a watershed. The so-called ?simple method? implemented by PLOAD and discussed in this thesis has been endorsed by the EPA as a viable screening tool for National Pollutant Discharge Elimination System (NPDES) stormwater projects. This model was designed to be used with ArcView 3.3. ArcView 3.3 is a depreciated product, the capabilities of which have been replaced by ArcGIS 9.1. Using the same GIS data and tabular data required by PLOAD and custom ArcObjects scripting, a replacement, ArcGIS-PLOAD, was created. The current version of ArcGISPLOAD implements the ?simple method? to calculate total pollutant load in pounds per year based on basin boundaries, precipitation in inches per year, ratio of storms producing runoff, parcel land use and parcel area, runoff coefficient for each land use, event mean pollutant concentrations for each land use. Time comparisons between the original PLOAD and the new ArcGIS-PLOAD revealed significant improvements. Both versions of PLOAD produce an intersection between the basin boundary and the land use layer. Calculations are actually done to the intersect layer. It was also found that the original PLOAD disregarded an albeit small portion of the intersection polygons. The new version does not. With the creation of ArcGIS-PLOAD, it is anticipated that it will become a small step in assist the State of Texas in improving water quality.Item Effect of alkalinity in irrigation water on selected greenhouse crops(Texas A&M University, 2005-11-01) Valdez Aguilar, Luis AlonsoEffect of Alkalinity in Irrigation Water on Selected Greenhouse Crops. (August 2004) Luis Alonso Valdez Aguilar, B.S., Universidad Aut??noma de Nuevo Le??n, Mexico; M.S., Universidad Aut??noma Chapingo, Mexico Chair of Advisory Committee: Dr. David Wm. Reed Bicarbonate (HCO3-) and carbonate (CO32-) are the most important ions that determine alkalinity. When the carbonates accumulate in a growing medium, the growing medium solution pH reaches levels that cause plant growth inhibition, which is caused primarily by the transformation of soluble forms of Fe into insoluble forms. The general objective of this research was to provide information about the limits of tolerance to alkalinity in ornamental plants, and to study the interaction of ions such as ammonium (NH4+) and nitrate (NO3-) on the response of plants to alkalinity, as well as the effect of the counter-ions potassium (K+), sodium (Na+), cesium (Cs+), ammonium (NH4+) and rubidium (Rb+). The maximum SPAD index was estimated to occur at 0 mM of NaHCO3 in chrysanthemum, mini-rose, and hibiscus ??Bimini Breeze?? and ??Mango Breeze??. For vinca it was set at 2.64 mM. A 15% decrease from the maximum SPAD index was considered the threshold to declare the toxic concentration of NaHCO3, which was calculated based on the maximum SPAD index predicted by the models. The toxic concentration of NaHCO3 was set at 4.1, 1.1, 6.7, 3.1, and 6.3 mM of NaHCO3 in chrysanthemum, mini-rose, vinca, and hibiscus ??Mango Breeze?? and ??Bimini Breeze??, respectively. Hibiscus ??Bimini Breeze?? was considered tolerant to alkalinity, due to increased Fe-reduction capacity and acidification of the growing medium. In the hydroponic experiment, results showed that the NH4+:NO3- ratio altered the response of sunflower plants to alkalinity. Sunflower plants grew better in solutions containing 5 mM NaHCO3 prepared with a 0.25:0.75 NH4+:NO3- ratio. This was possible due to the reaction of NH4+ with the HCO3-, which reduced its buffering capacity. The response to HCO3--induced alkalinity was modified by the counter-cation of HCO3-. In bean plants, at low-to-intermediate levels of Na+ and HCO3- induced approximately same growth decrease. At high concentration, Na+ induced a decrease on shoot growth that exceeded the toxic effects of HCO3-. Thus, the toxic effect of Na+ is higher than that of HCO3- when its concentration is high. Rubidium was extremely toxic at concentrations of 7.5 mM.Item Effects of Anthropogenic Nutrient Enrichment on Exotic and Restored Native Aquatic Vegetation(2012-07-16) Parnell, AllisonUnderstanding how nutrient input into coastal wetlands influences aquatic vegetation and the fate of anthropogenic nutrient inputs can help improve water quality management plans. The goals of this study were to (1) compare nutrient concentrations in various storage compartments downstream from two point nutrient sources (a sewage treatment plant outfall and a residential detention basin) in Armand Bayou, a coastal brackish wetland in the Galveston Bay (Texas, USA) watershed, and (2) determine if nutrient storage in those compartments helped improve water quality downstream. Water column nutrients can be assimilated by aquatic vegetation, adsorbed to sediment, or diluted within the system as distance from source input increases. To determine the fate of nutrients to Armand Bayou, I measured nutrient concentrations in the sediment, water column, pore water, and tissue of exotic and restored native plants downstream from a sewage treatment plant and a residential detention basin. To assess nutrient removal potential of a common exotic species, I determined relative growth and nutrient uptake rates of Eichhornia crassipes. Water column total nitrogen, NH?? and NO?? concentrations decreased by 95, 96 and 99 percent downstream from the sewage outfall (~2200 m distance). Water column NH?? and NO?? concentrations decreased by 93 and 75 percent downstream from the detention basin (~2500 m distance). Exotic species Alternanthera philoxeroides, Pistia stratiotes and E. crassipes showed higher aboveground/emergent tissue nutrient content than restored, native Schoenoplectus californicus for both tributaries. Schoenoplectus californicus had the largest biomass although appeared to be limited in its ability to remove nitrogen from the water column. Nutrient uptake rates by E. crassipes were low and did not change with increasing distance from nutrient source, but high relative growth rates in both tributaries suggest the nuisance potential of this exotic species. Low sediment and pore water nutrient concentrations for both tributaries suggest these compartments are not sinks. All plant species did not respond to changes in water column nutrient concentrations with increasing distance from source input suggesting dilution to be the main factor in water column nutrient decline for both tributaries. This study will provide water quality resource managers guidance on the development of total maximum daily loads (TMDLs) for water bodies impaired by high nutrient loading and the implementation of wetland plants efficient in nutrient removal for water quality improvement.Item Effects of composted dairy manure on soil chemical properties and forage yield and nutritive value of coastal Bermudagrass [Cynodon dactylon (L.) Pers.](Texas A&M University, 2005-02-17) Helton, Thomas J.Research was conducted to compare the effects of composted dairy manure and raw dairy manure alone, or in combination with supplemental inorganic fertilizer, on soil chemical properties and Coastal bermudagrass [Cynodon dactylon (L.) Pers.] yield and nutritive value. Composted dairy manure was surface applied at rates of 14 (125 kg N ha-1), 29 (250 kg N ha-1) and 57 (500 kg N ha-1) Mg dry matter (DM) ha-1, and raw dairy manure was surface applied at a rate of 54 (420 kg N ha-1) Mg DM ha-1 to established bermudagrass. Selected compost and manure plots received supplemental inorganic N at rates of 56, 84 and 112 kg ha-1 cutting-1 or 112 kg ha-1 cutting-1 of supplemental N with supplemental inorganic phosphorus or potassium at rates of 112 kg P2O5 ha-1 yr-1 and 112 kg K2O ha-1 cutting-1, respectively. Composted dairy manure (29 and 57 Mg DM ha-1) or raw manure alone increased cumulative forage yields compared to the untreated check in both years of the study, but were less than those obtained using only inorganic fertilizer. Application of 56 kg N ha-1 cutting-1 or more of supplemental N to compost (29 and 57 Mg DM ha-1) or iv manure produced forage yields that were equal to or greater than those obtained using inorganic fertilizer alone. However, increasing compost rate did not increase tissue N concentrations regardless of supplemental inorganic N rate. Yield and tissue K concentrations were increased in the second growing season when supplemental inorganic K was applied to 29 Mg ha-1 of compost or 54 Mg ha-1 of raw dairy manure. No yield response was observed when supplemental inorganic P was applied to compost or manure. Soil pH and concentrations of NH4, NO3, K, Ca, Mg and Mn were increased by application of compost or manure. Soil P concentrations in the 0 to 5-cm zone exceeded 200 mg kg-1 when compost was applied at the high rate. Dairy manure compost was an effective nutrient source for bermudagrass hay production, but will require the use of supplemental N and, in some cases, K to achieve yields comparable to inorganic fertilizer.Item Effects of UV Light Disinfection on Tetracycline Resistant Bacteria in Wastewater Effluents(2011-10-21) Childress, HannahThe ubiquitous use of antibiotics has led to an increasing number of antibioticresistant bacterial strains, including strains that are multidrug resistant, pathogenic, or both. Numerous studies have been conducted showing the presence of antibioticresistance genes (ARGs) and antibiotic-resistant and multidrug resistant bacteria in wastewater and drinking water treatment plants. There is also evidence to suggest that ARGs spread to the environment, and to humans and animals, through wastewater effluents. The overall objective of this study was to investigate the effect of UV light disinfection on ARGs and antibiotic resistant bacteria. Wastewater effluent samples from a wastewater treatment plant (WWTP) in Texas were evaluated for differences in abundance and diversity of tetracycline resistant bacteria before and after UV treatment. The effects of photoreactivation or dark repair on the reactivation of bacteria present in WWTP effluent after UV disinfection were also examined. Culture based methods were used to characterize viable heterotrophic, tetracycline resistant heterotrophic, E. coli, and tetracycline resistant E. coli bacteria present before and after UV treatment. Molecular methods were used to characterize the diversity of organisms present and to test for the presence of tet(Q), a tetracycline resistance gene associated with human origins. UV disinfection was found to be as effective at reducing concentrations of resistant heterotrophs and E. coli as it was at reducing total bacterial concentrations. The lowest survival ratio following UV disinfection was observed in tetracycline-resistant E. coli, showing it to be particularly susceptible to UV treatment. Photoreactivation and dark repair rates were found to be comparable to each other for all bacterial populations. UV disinfection was found to significantly alter the community composition of tetracycline-resistant bacteria, though it did not have the same effect on the total bacterial community.Item Evaluation of Methods to Assess and Reduce Bacterial Contamination of Surface Water from Grazing Lands(2012-10-19) Wagner, KevinExcessive bacterial levels are a major water quality concern. Better methods are needed to quantify the proportion of bacterial loading contributed by various sources, and best management practices are needed to restore water quality. This study assessed the ability of alternative water supplies and grazing management to reduce E. coli loading from cattle and evaluated the ability of quantitative polymerase chain reaction analysis of total and bovine-associated Bacteroides markers (AllBac and BoBac, respectively) to determine the percentage of bovine-associated fecal contamination. Runoff from seven small watersheds, representing ungrazed, properly stocked, and overstocked conditions, was analyzed for E. coli, AllBac, and BoBac to assess grazing management impacts on E. coli runoff and the effectiveness of Bacteroides markers. To determine the effectiveness of alternative water, instream E. coli levels and cattle movement were evaluated before and after alternative water was provided. The study found that when alternative off-stream water was provided, the amount of time cattle spent in the creek was reduced 43 percent and the direct deposition of E. coli into Clear Fork of Plum Creek was estimated to be reduced from 1.11E 07 to 6.34E 06 colony forming units per animal unit per day. Observed pre- and post-treatment E. coli loads suggested similar reductions; however, this study could not conclusively attribute observed E. coli loading reductions to providing alternative water because of the lack of statistical significance of these observations, possibly due to decreased streamflow during Year 2 (due to drought) and a corresponding increase in E. coli levels. The study found that rotational stocking, if timed appropriately, was very effective at reducing E. coli runoff. The impact of grazing timing in relation to runoff events was more significant than the impact of grazing management (i.e. ungrazed properly stocked or overstocked) or stocking rate. When runoff occurred more than two weeks following grazing, E. coli levels in runoff were decreased more than 88 percent. Finally, data suggest that AllBac and BoBac markers are good indicators of recent fecal contamination from cattle. However, although elevated BoBac/AllBac ratios generally aligned well with cattle presence, this ratio appeared to underestimate the percentage of bovine-associated fecal contamination.Item Factors Influencing the Adoption of Water Quality Best Management Practices by Texas Beef Cattle Producers(2014-05-28) Peterson, JenniferThe management of agricultural nonpoint source pollution is complex due to the diffuse nature of the various sources. As a result, rather than relying on direct regulation, natural resource agencies generally utilize a watershed approach to encourage the voluntary adoption of best management practices (BMPs) to improve water quality and control nonpoint source pollution originating from livestock, farm, and forestry operations as well as urban nonpoint sources. Policy tools used to encourage voluntary adoption include educational programming as well as technical and financial assistance opportunities. Despite the known water quality benefits of BMPs and the availability of policy tools to encourage adoption, some landowners and livestock producers choose not to adopt conservation practices. This study examined the current adoption behavior of Texas beef cattle producers and investigated how factors related to capacity, attitudes, environmental awareness, and farm characteristics influenced the adoption of BMPs known to reduce levels of bacteria, sediment, nutrients, and other contaminants in runoff. A statewide mail survey of beef cattle producers was conducted in the Fall of 2013. Univariate probit analysis was used to estimate the influence of 30 predictor variables on the probability of a beef cattle producer adopting 18 different water quality BMPs. Results from the analysis show producers are adopting and maintaining water quality BMPs despite a significant lack of knowledge concerning common water quality terms and the availability of financial assistance programs to aid in practice implementation. The most significant predictors of adoption among survey respondents included visits with Extension, prior participation in a government cost-share program, crop diversity, annual income, and percent income from the operation. The most significant factors reducing the probability of adoption among survey respondents included education, gender, visits with NRCS, membership in a livestock organization, and having a family member take over the operation. These results suggest the need to address information gaps among beef cattle producers as well as demonstrate a significant opportunity for the NRCS and Extension to forge a strategic long-term partnership to promote increased and sustained adoption of water quality BMPs.Item Prioritizing Water Pipe Replacement and Rehabilitation by Evaluating Failure Risk(2012-02-14) Lee, Sang HyunEssential to human life is water. Drinking water, in particular, is of utmost significance for all living creatures including man. An examination of the transmission process of drinking water reveals the high importance of pipe lines. The water pipe lines delivering water today encounter serious problems. Corrosion has caused deterioration in pipe lines, which contributes rust to drinking, a serious water quality problem. In addition, pipe line failures have caused social issues, such as suspension of water supply. This study developed a model to estimate the life expectancy and residual life of a pipe based on the assessment of failure risk in order to evaluate the current failure possibility and predict when the pipe will reach the point of failure. The developed model for estimation of residual life by failure risk was used to assess the failure risk of water pipes based on the general data and pipe sources of the Chang Won City water pipes. The efforts to diagnose and evaluate water pipes are limited to the assessment of current pipe conditions, which is why they can easily determine the priority of rehabilitation based on the current pipe conditions but have hard time getting information about how the pipes have deteriorated to the point of requiring rehabilitation. The objectives of this study are: (1) develop a model for estimating corrosion rates and residual thickness of water pipes, (2) assess loads and stress affecting water pipes, (3) to estimate damage risk, and (4) calculate safety factors. Results of the study could help reduce rehabilitation costs and secure water quality after renovation. Thus it would contribute to the safe and stable operation and management of pipe networks by increasing the life of water pipes.Item Studies on Waterborne Pathogen Reactivation after Disinfection(2013-12-09) Kaur, JasjeetReactivation of different Escherichia coli strains and Aeromonas hydrophila after ultraviolet (UV), ultrasound, and photocatalytic disinfection treatments was addressed in this study. Photocatalytic disinfection was carried out under low pressure ultraviolet (LP UV) irradiation at five titanium dioxide (TiO_(2)) concentrations (1 g/L, 0.5 g/L, 0.75 g/L, and 0.1 g/L) to achieve 5 log_(10) reduction of a laboratory E. coli K-12 strain (ATCC? 10798). Regrowth and reactivation of E. coli in dark and light was studied up to 4 h after disinfection period. During the repair period, flow cytometry had shown 4-5 log_(10) higher cell counts than culture based method. Photocatalysis at 0.1 g/L TiO_(2) had resulted in 50% cells with intact cell membrane during the repair period and has lowered the repair rate of the E. coli (ATCC? 10798) after disinfection. Then ultrasound (24 kHz) and UV-C irradiation were applied to inactivate four E. coli isolates (ATCC?10798, E. coli isolate from feces of feral hog and deer, and treated wastewater effluent) to nearly 8 log_(10) reduction. Photoreactivation and dark repair of E. coli isolates were studied over a 24 h period after disinfection. In general, ultrasound disinfection had resulted in higher inactivation rate of 0.52 log min^(-1) than UV-C (0.39 log min^(-1)) for E. coli isolates. The extent of percent log repair of ultrasound inactivated E. coli isolates after 24 h of dark repair and photoreactivation were 30% lower than after UV-C. The metabolic activity of E. coli cells was greatly reduced after ultrasound as shown by AlamarBlue? assay. Transmission electron micrographs of ultrasound disinfected E. coli revealed shearing and size reduction of bacterial cells. Aeromonas hydrophila (ATCC? 35654), an emerging pathogen, was inactivated using a 24 kHz continuous ultrasound and UV-C in combination with three TiO_(2) concentrations (1g/L, 0.1 g/L and 0 g/L). High inactivation rate of 1.52 log min^(-1) was observed for ultrasound disinfection in absence of TiO_(2). Aeromonas hydrophila had showed a net log reduction of 6 log_(10) after ultrasound exposure in comparison to a net 2 log_(10) reduction after UV-C over a 24 h repair period. Metabolic activity of Aeromonas hydrophila was adversely affected by ultrasonication as well. Ultrasound appears to be effective in inactivating environmental E. coli isolates and Aeromonas hydrophila in water through shearing and breaking effects, which decreased the metabolic activity as well as photoreactivation and dark repair.Item Surface Water Chemistry in White Oak Creek, North-East Texas: Effect of Land Use(2012-02-14) Watson, ElizaOver the last few decades increasing attention has been paid to the effects of land use activities and land management on stream water quality. Recent research has largely focused on dominant land uses such as urban development and agricultural cropland. The relative effect of land use activities and management on stream chemistry in sub-tropical rangeland ecosystems, where much of the land use is converted to pasture and agriculture is largely unknown. This study examined stream water quality and land use in a sub-tropical watershed in Northeast Texas largely dominated by rangeland. The study site, White Oak Creek Watershed located in the Sulphur River Basin, has been identified as an impaired stream due to low dissolved oxygen concentrations and subsequently listed on the Texas Commission for Environmental Quality's 303d list (TCEQ). In an attempt to determine potential sources of the low dissolved oxygen concentrations, twenty different chemical constituents were analyzed at 18 different sample sites in the tributaries of White Oak Creek and also along the main stem from April 2010 to March 2011. Dissolved oxygen concentrations over the study period were consistently above the minimum standard required by TCEQ and showed no indication of impairment. Correlation analysis did not show any clear correlation between dissolved oxygen and any specific land use, or any chemical constituent. Some nutrients and suspended sediment concentrations were significantly different among the sub-catchments of White Oak Creek. Urban land uses were significantly and positively correlated to electrical conductivity, ammonium-N, magnesium, calcium, and dissolved organic carbon. Agricultural land use was significantly and positively correlated to orthophosphate-P, dissolved organic nitrogen, total suspended solids, and turbidity. Forests were inversely and significantly related to nitrate-N, orthophosphate-P, sulfate, dissolved organic carbon, total suspended solids, and turbidity. The study suggested that by maintaining a relatively high proportion of forested land in a watershed that water quality can be improved.Item Sustainable Water Supply: Rainwater Harvesting for Multistoried Residential Apartments in Dhaka, Bangladesh(2009-05-15) Sultana, FarzanaRainwater harvesting is a familiar term for Bangladesh. People in areas that lack drinking water, particularly the coastal areas and the rural areas in the country, practice rain water harvesting. The high annual rainfall in the country makes rainwater harvesting a logical solution for the arsenic contamination of ground water in Bangladesh (Rahman et al. 2003). Also, the increasing population in the urban as well as rural areas is putting increased load on underground aquifers which is evident in the fact that the piezometric level in Dhaka has decreased by more than 65 feet in the last decade. The annual rain fall that the city receives may be an effective answer to the recharge of aquifers. Rain water harvesting during the rainy season can reduce the increasing load on groundwater levels. This study aims to provide some guidelines for economic rainwater harvesting system, especially for urban areas for specific user groups. These guidelines were formulated through literature review, analysis of some case studies on rainwater harvesting, and, to a certain extent, practical experience of the researcher. Data from secondary sources have also been used for the purpose. The guidelines have been formulated using existing data on rainwater harvesting systems. Based on these guidelines, a mathematical model has been developed to figure out cistern sizes for collection of rainwater. The solution is applied to a typical plan of an apartment house in Dhaka (multistoried) using programming and visualization so as to demonstrate the scope and benefit of integration of rain water harvesting technique with the architectural design. The harvested rainwater definitely does not meet the basic domestic requirement, but supplements it during the rainy season which, most importantly, is usable for individual household use. Large-scale rainwater harvesting also, hopefully, results in a decrease of seasonal flooding in the urban areas. The products of this research are a) a computer program for sizing cisterns and b) an animation of the proposed rainwater harvesting system that may be used as a tool to demonstrate the benefits of the technique.