Browsing by Subject "Water -- Pollution"
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Item Characterization of bridge discharge to receiving streams(Texas Tech University, 2004-12) Nishtala, SantoshNot availableItem Fate of perchlorate in natural systems: intrinsic biodegradation, plant uptake, and remediation potential of wetlands(Texas Tech University, 2003-08) Tan, KuiPerchlorate (CIO4) has recently become a nationwide concern due to contamination in soil, sediment, surface water, and groundwater. Laboratory and field studies were initiated (1) to examine the potential of wetland systems to treat perchloratecontaminated waters, (2) to determine the intrinsic degradation kinetics in sediments and soils from multiple sites, and (3) to determine the fate of perchlorate in streams and near-surface sediments, including temporal and spatial distribution, plant uptake, and biological transformation potential. Results indicated that artificial wetlands might be a promising technology to treat perchlorate-contaminated waters, especially suitable for groundwater plumes or non-point surface water at lower perchlorate concentration levels. Wetland treatment efficiency was mainly controlled by nitrate concentration, organic substrate availability, and reoxygenation near the surface. Microbial degradation played a more important role than plant uptake and ftansformation in this type of wetland system. Perchlorate degradation rates and lag times in sediments and soils were site-specific and dependent on numerous environmental conditions, such as organic substrate availability, nitrate, initial C104' concentration, and prior exposure. Perchlorate degradation rates were mainly affected by organic substrate availability; lag time was mainly controlled by nitrate concentration and organic substrate availability. Rapid natural attenuation of perchlorate in sediments of natural habitats was demonstrated using in-situ dialysis samplers (peepers). Perchlorate penetration and persistence were found seasonally variable, with colder season showing the highest penetration. Biodegradation of perchlorate occurred over a depth of only 1-10 cm, and this active depth changed seasonally. Perchlorate distribution closely mirrored nitrate distribution in sediments. There was a large potential of perchlorate uptake in a variety of aquatic and terrestrial plants. Perchlorate uptake in aquatic plants from streams was up to two orders of magnitude higher than the bulk water concentration. Perchlorate uptake in tertestrial plants was dependent on exposure duration, species, and accessibility of perchlorate source. Plants may become the source and sink of perchlorate. This research has elucidated the fate of perchlorate in natural systems and highlighted the potential of using wetlands to treat perchlorate-contaminated water.Item Lagoon treatment of combined textile and domestic wastes(Texas Tech University, 1974-05) Opitz, Danny CarlNot availableItem Natural Resources Conservation Service curve number analysis for Texas(Texas Tech University, 2001-05) Atkinson, Erin L.This study was the fírst step in a research project for the Texas Department of Transportation (TxDOT). The overall project was to investigate whether or not climatic adjustments need to be made to the Natural Resources Conservation Service (NRCS) runoff curve number (CN) method. An important task in the project was to compare predicted curve numbers whh curve numbers calculated from measured rainfall-runoff data. The primary objective of the research reported in this thesis was to develop a procedure using a geographic information system (GIS) to compute CN. The measured rainfall-runoff data for the research project was collected from historical small watershed studies conducted by the United States Geologic Survey (USGS). A secondary objective was to compare GlS-computed CN with observed CN generated from USGS data.Item Pollution of storm runoff from a small residential watershed(Texas Tech University, 1970-08) Brownlee, Robert CNot availableItem The fate of pesticides applied to lake beds and surrounding water sheds(Texas Tech University, 1966-05) Forehand, Charles EwenNot availableItem Variation in flow and flow quality from a semi-arid urban watershed.(Texas Tech University, 1975-12) Gibson, Robert MarkThis study had two major objectives. The first objective consisted for the utilization of various predictive flow models to predict the total volume and peak runoff from a gaged watershed. The predictive flow models utilized were the rational method, the Viessman and Miller method, the Viessman, Keating, and Srinivasa method, and the British Road Research Method. Using three storms of varying characteristics, the total runoff volume and peak flow from the predictive models were compared to the observed total runoff and peak flow in each case. The second major objective of the study was the utilization of regression analysis to ascertain whether or not predict relations could be derived to relate individual pollutant concentrations to dry weather flow volume; and individual dry weather flow pollutant concentrations to antecedent storm characteristics. The individual pollutant concentrations utilized were COD, BOD, total solids, suspended solids, phosphates, and nitrates. The antecedent storm characteristic consisted of duration of antecedent event, amount of antecedent event, days since antecedent event, and average intensity of antecedent event.Item Variation of urban runoff quality and quantity with duration and intensity of storms.(Texas Tech University, 1974-08) Thompson, Gary BurtonNot availableItem Water pollution from cattle feedlots(Texas Tech University, 1970-08) Malouf, John BorjisNot available