Browsing by Subject "Remediation"
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Item A Meta-analysis of Mercury Levels in Lavaca Bay Texas(2014-05-07) Pillado, Maria C.Lavaca Bay is a secondary bay to Matagorda Bay on the central Texas Coast. In 1970 Texas Department of Health (TDH) closed parts of Lavaca Bay to the harvesting of oysters due to mercury contamination as a result of contaminated wastewater discharged into the bay by a chlor-alkali plant operated by Alcoa. In 1988 TDH closed the area around Dredge Island which is adjacent to the chlor-alkali plant to the taking of finfish and crabs due to elevated mercury levels. In 1994 it was proposed that the area around Dredge Island and area around the chlor-alkali plant were placed on the National Priorities List (NPL). In December of 2001 the Record of Decision (ROD) was signed to initiate the remediation process. The purpose of this study is to use a meta-analysis to determine if the mercury levels in secondary and tertiary trophic levels have changed between years 1992 and 2012, and if the levels in red drum (Sciaenops ocellatus) and oysters (Crassostrea virginica) have decreased over time. The meta-analysis used biota and sediment collected and analyzed for total mercury in 2012, historical data from Texas Department of Health (TDH), U.S. Environmental Protection Agency (EPA), and Woodward-Clyde (1992).Item An assessment of the design of in situ management approaches for contaminated sediments(2010-05) Lampert, David; Reible, Danny D.; Gilbert, Robert; Katz, Lunn; Kinney, Kerry; Montagna, PaulSediments serve as the ultimate sink for many hydrophobic organic compounds and thus present a residual environmental risk many years after sources of contamination are eliminated. Monitored natural attenuation and ex situ treatment processes are often ineffective for treatment; as such in situ remediation technologies (i.e., capping) are under review. A conventional in situ remediation technology for refractory sediment contaminants is placement of a clean layer of material as a cap. A series of design models was developed to predict the performance of caps composed of the traditional material, sand. A passive sampling method using polydimethylsiloxane (PDMS) fibers for evaluating the performance of caps was developed and tested in the laboratory. The results of the laboratory analysis showed the ability to measure pore water concentration profiles in caps, the consistency of profiles with design model predictions, and correlation of PDMS-derived concentrations with contaminant uptake in test organisms. Potentially more effective caps composed of permeable adsorptive materials (to retard contaminant migration) and impermeable materials (to divert groundwater flow) were placed along with a conventional sand cap in the Anacostia River in Washington DC in 2004. Field tests of this site showed the ability to measure in situ pore water concentration profiles in caps using a field-deployable version of the PDMS passive sampling device and demonstrated the necessity of pore water-based approaches for analyzing caps. A model for assessing the uptake rates of HOCs within PDMS fibers was developed and shown to predict the kinetics of HOC sorption into fibers. The model is based on external-mass transport processes, which through a series of analyses were shown to be more significant than internal diffusion in PDMS fibers. Using the PDMS approach, field bioaccumulation tests at the Anacostia site as well as at San Diego Bay and Hunters Point Naval Shipyard showed stronger correlation of PDMS-based pore water concentrations than solid-phase concentrations with observations of bioaccumulation in the field. The overall conclusions suggest that pore water concentrations can often be a better indicator of risk than bulk solid concentrations.Item Differences in graduation rates and postsecondary enrollment as a function of ethnicity/race, school poverty, and school size: A Texas multiyear investigation(2016-10-21) Perez, Angeles M.; Slate, John R.; Barnes, Wally; Moore, George W.; Lunenburg, Frederick C.The purpose of this journal ready dissertation was to ascertain the relationship of high school size with graduation rates and postsecondary enrollment status for students in Texas. In the first study, the relationship of school student enrollment percentages with graduation rates for Black, Hispanic and White graduates was examined. In the second study, the extent to which school poverty was related with graduation rates for Black, Hispanic, and White graduates was ascertained. Finally, in the third research article, the relationship between school poverty and postsecondary enrollment status of Texas graduates was determined. Analyzed in each empirical investigation were two years of statewide public school data. A non-experimental, causal-comparative research design (Johnson & Christensen, 2012) was utilized in this investigation. Archival data were obtained from the Texas Education Agency Academic Performance Report database for the 2012-2013 and 2013-2014 school years. The variables that were analyzed as a function of school size and school student enrollment poverty percentages for students in Texas were: graduation rates, enrollment in Texas higher education institution rates, and completion of one year of Texas higher education without remediation rates. Statistically significant results were revealed in each of the three investigations. An examination of graduation rates for Black students as a function of school size revealed that Moderate-Size schools was the optimal size. Hispanic students however, had higher graduation percentages from Large-Size schools with White students having higher graduation percentages from Small-Size schools. Graduation rates of Black, Hispanic, and White students differed by school student enrollment poverty percentages. For Black and Hispanic students, the highest graduate percentages were from High Poverty schools whereas Low Poverty schools had the highest graduate percentages for White students. Lastly, the postsecondary enrollment status of high school graduates differed as a function of school poverty. High Poverty schools had the lowest enrollment rates in higher education institutions and the lowest completion rates of one year of higher education without remediation. Results from this journal-ready dissertation were congruent with much of the recent empirical literature. Implications for policy and recommendations for research were provided.Item Enzyme-based detoxification of organophosphorus neurotoxic pesticides and chemical warfare agents(2009-05-15) Kern, Rory JamesThere are some 15,000 known organophosphorus chemicals. Some of these OP?s, including VX and paraoxon, demonstrate an acute neurotoxicity due to the inhibition of cholinergic enzymes. Organophosphorus chemical warfare agents and pesticide neurotoxins are subject to hydrolysis by OP degrading enzymes. To be useful as a bioremediation or anti-chemical warfare agent, the enzyme must be tailored for, and integrated into, a practical application platform. Several studies have established enzyme-based countermeasures, describing such diverse applications as decontaminating foams for surface remediation, encapsulating enzyme with liposome for in vivo therapy, enzyme attachments to surfaces for biosensors and development of a corn expression system for large-scale enzyme production. The goal of the research described here is to select, investigate and improve the operational potential of organophosphate-degrading enzymes including Organophosphorus Hydrolase (OPH, 3.1.8.1) and Organophosphorus Acid Anhydrolase (OPAA, 3.1.8.2). Using saturation kinetics, the catalytic efficiencies of these two major detoxification enzymes were characterized with substrates representing each class of OP neurotoxin, phosphotriester, phosphothioate and phosphofluoridate. OPH presents superior kinetic parameters with each OP class tested. Variants of OPH were created to increase the operational effectiveness of OP hydrolytic enzymes against phosphorothioates. An H254S/H257L mutation in the active site resulted in an improvement in the kinetics (kcat/KM) for the phosphorothioate, demeton-S. To screen potential vascular protection therapies, an in vitro protocol was developed to predict enzymatic effectiveness for protection of acetylcholinesterase from acute OP-inhibition. The protection abilities of the enzymes were directly related to their second order rate constants as inhibitory levels of OP are below the KM of the enzymes. Consideration of contaminant nature concentration and enzyme kinetic parameters, kcat and KM, is critical to understanding decontamination and effective use of enzyme technology. These technologies continue to develop and provide promising new decontamination tools for OP compounds.Item Evaluating organic compound sorption to several materials to assess their potential as amendments to improve in-situ capping of contaminated sediments(2011-05) Dunlap, Patrick John; Reible, Danny D.; Liljestrand, HowardContaminated sediments represent a common environmental problem because they can sequester large quantities of contaminants which can remain long after the source of pollution has been removed. From the sediment these hazardous compounds are released into the sediment porewater where it can partition into organisms in the sediment and bioaccumulate up the food web; leading to an ecological and human health concern. The objective of this work is to investigate an emerging option in contaminated sediment remediation; specifically an option for in-situ treatment known as active capping. Conventional capping uses clean sediment or sands to separate contaminated sediment from overlying water and biota. Active capping is the use of a sorptive amendment to such a cap to improve its effectiveness. This work focuses on granular materials as direct amendments to conventional caps including; granular activated carbon (GAC), iron/palladium amended GAC, alumina pillared clay, rice husk char, and organically modified clays. All materials were investigated in batch sorption tests of benzene, chlorobenzene, and naphthalene in DI water. Additionally porewaters from three sites were extruded and the concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured. At Manistique Harbor and Ottawa River PCBs were identified as the primary contaminant of concern while PAHs were the contaminant of concern at the Grand Calumet River. At these sites a solvent extraction method was used to analyze the sediment concentrations of the contaminants of concern. From the former batch tests activated carbon and a commercially available organoclay were chosen for further investigation. This includes PAHs in batch sorption tests using extruded sediment porewater to investigate matrix effects, and PCB sorption in distilled water.Item Evaluation of sorbing amendments for in-situ remediation of contaminated sediments(2015-08) Azhar, Wardah; Liljestrand, Howard M. (Howard Michael); Reible, Danny D.; Speitel, Gerald E.; Freeman, Benny D.; El Mohtar, ChadiContaminated effluents reaching surface water bodies have led to accumulation of contaminants in sediments. The significance of contaminated sediments has increased as we have cleaned up effluents, often representing the primary human and ecological health risk remaining in surface waters. Contaminants such as polychlorinated-biphenyls (PCBs) and certain metals are bioaccumulative and reach high doses as they travel to higher trophic levels. Monitored natural attenuation and ex-situ treatment are often ineffective and uneconomical, and placing clean inert material over sediments as a cap is sometimes insufficient to adequately reduce risk so sorptive amendments are increasingly being considered to reduce the availability and mobility of contaminants. Laboratory sorption tests with different contaminants and sorbents were conducted to screen potential sorbent materials. Contaminants used in these screening studies included hydrophobic organic and selected inorganic contaminants common to sediments and sorbents included five types of clays and four types of carbon based sorbents. These screening studies were used as a basis to evaluate an in-situ adsorptive remedy for a particular site, the Manistique Harbor and River Superfund site in Michigan. Sorption capacity of five polychlorinated biphenyls (PCBs) on granular activated carbon (GAC) and organophilic clay (OMC) and the influence of natural organic matter (NOM) was evaluated. Results show that NOM fouling reduces performance of GAC by about half an order of magnitude while having minimal effect on OMC. Measured performance of the sorbents was used to evaluate in-situ treatment and capping remedial designs under conditions of weak (1 cm/yr) and rapid (1 cm/day) upwelling flow. Amended capping where the cap material is mixed throughout a thick cap layer provides the best performance, followed by capping in a thin layer followed by use of amendments as an in situ treatment. A Polanyi based adsorption prediction model was developed to predict GAC performance degradation by NOM that requires only micropore volume of GAC and physico-chemical properties of adsorbate for prediction. It accurately predicts adsorption even for a different type of GAC and different source of NOM. Results suggest that NOM-associated reduction of GAC micropore volume is a good indicator of the performance degradation associated with NOM.Item Geotechnical containment of non aqueous phase liquid contaminated sediments(2012-05) Erten, Mustafa Bahadir; Gilbert, Robert B. (Robert Bruce), 1965-; El Mohtar, Chadi Said; Charbeneau, Randall J.; Reible, Danny D.; Lake, Larry L.In situ capping is a remediation alternative for contaminated sediments which has been implemented to contain contaminants in sediments in rivers, lakes and ponds. One concern with in situ capping is that the additional load due to the in situ cap may cause consolidation-induced mobilization of non aqueous phase liquids (NAPL). Therefore, it is important to understand the consolidation behavior of NAPL contaminated soils. The difficulties of testing river-bed sediments are that these sediments usually are very soft, have very high porosities, and are very compressible. In addition, the contaminants in these sediments should be contained during testing. The primary objective of this research is to investigate the behavior of NAPL contaminated sediments under anisotropic consolidation. A modified triaxial testing system was developed to simulate the consolidation of very soft sediment specimens along with a reconstituted NAPL contaminated specimen preparation procedure. Kaolinite and Anacostia River sediments were used for the sediments’ solids phase. A low viscosity mineral oil, Soltrol 130, was used to represent the NAPL phase. Tap water was used as the water phase. PM199TM, a type of organophilic clay manufactured by CETCO, was used as well to study its effectiveness in containing expelled NAPL. Two sets of consolidation tests were performed: 1) tests on sediment specimens at various NAPL contents and porosities; and 2) tests on specimens contaminated with NAPL with organophilic clays either placed as a layer on top or mixed within the sediment. The results showed that NAPL mobilization was negligible below a threshold NAPL content. Hydraulic conductivities increased with increasing NAPL content up to four orders of magnitude. The tests with organophilic clay showed that when large enough amounts are used, NAPL expulsion can be completely stopped. Organophilic clay reached its full capacity independent of the NAPL content of the underlying sediment.Item Groundwater remediation at a former oil service site(Texas A&M University, 2005-08-29) Han, LipingAs an intern with URS Corporation, I participated in several remediation and wastewater treatment projects during the year 2004. A groundwater remediation project was selected to present in this record of study for my Doctor of Engineering degree not only because I spent more time on it than any other project, but also because it represents the broadness and depth of a typical URS remediation project. In this report, findings from previous environmental investigations were summarized and used for computer modeling and remediation strategy evaluation. Computer models were used to simulate site conditions and assist in remedy design for the site. Current pump-and-treat systems were evaluated by the model under various scenarios. Recommendations were made for the pump-and-treat system to control the contaminant plume. Various remediation technologies were evaluated and compared for their applicability at the site. A combination of on-site remediation and downgradient plume control was chosen as the site remediation strategy. Treatability studies and additional modeling work are needed for the remediation system design and optimization.Item Improving performance in first year chemistry(2005-08) Chambers, Kent A.; Blake, Bob; Casadonte Jr., Dominick J.; Poirier, Lionel W.General Chemistry is a degree requirement for over thirty different baccalaureate degrees offered by Texas Tech University. Historical success rates for this course have been low, with overall attrition rates as high as 70% in some years. Students are placed into either General Chemistry or Introductory Chemistry based on their performance on a chemistry placement exam. This dissertation contains in-depth studies on improving student performance and reducing attrition in both Introductory and General Chemistry classes. There is a high statistical correlation between student performance in Introductory Chemistry and student performance in General Chemistry in the following semester. Since 70-80% of the students are placed into Introductory Chemistry, it was postulated that by improving student performance in Introductory Chemistry, the student performance in General Chemistry would be significantly improved. Three different methods of improving student performance in Introductory Chemistry are discussed. The impact of these three methods upon student performance and attrition rates in Introductory Chemistry are evaluated in detail, as are their longitudinal effects on student performance in General Chemistry in the following semester. It was determined that all three methods significantly improved student performance and reduced attrition rates in Introductory Chemistry. It was also found that all three methods significantly increased student performance and decreased attrition rates longitudinally in General Chemistry. The relationship between student participation in classroom activities and student performance in General Chemistry was evaluated. This study showed that a significant percentage of the variance in final course grade was explained by student participation and attendance. Both student participation and attendance were determined to be good predictors of student success in General Chemistry Finally, a study using Just in Time Teaching (JiTT) techniques in General Chemistry was performed. This pedagogical approach and its effect on student performance and attrition is discussed. The class involved in the JiTT program was found to have significantly improved student performance and significantly reduced attrition rates in General Chemistry. In conclusion, this dissertation presents and discusses several studies focused on improving student performance and decreasing attrition rates in the first year chemistry curriculum at Texas Tech University.Item Improving performance in first year chemistry(Texas Tech University, 2005-08) Chambers, Kent A.; Blake, Bob; Casadonte Jr., Dominick J.; Poirier, Lionel W.General Chemistry is a degree requirement for over thirty different baccalaureate degrees offered by Texas Tech University. Historical success rates for this course have been low, with overall attrition rates as high as 70% in some years. Students are placed into either General Chemistry or Introductory Chemistry based on their performance on a chemistry placement exam. This dissertation contains in-depth studies on improving student performance and reducing attrition in both Introductory and General Chemistry classes. There is a high statistical correlation between student performance in Introductory Chemistry and student performance in General Chemistry in the following semester. Since 70-80% of the students are placed into Introductory Chemistry, it was postulated that by improving student performance in Introductory Chemistry, the student performance in General Chemistry would be significantly improved. Three different methods of improving student performance in Introductory Chemistry are discussed. The impact of these three methods upon student performance and attrition rates in Introductory Chemistry are evaluated in detail, as are their longitudinal effects on student performance in General Chemistry in the following semester. It was determined that all three methods significantly improved student performance and reduced attrition rates in Introductory Chemistry. It was also found that all three methods significantly increased student performance and decreased attrition rates longitudinally in General Chemistry. The relationship between student participation in classroom activities and student performance in General Chemistry was evaluated. This study showed that a significant percentage of the variance in final course grade was explained by student participation and attendance. Both student participation and attendance were determined to be good predictors of student success in General Chemistry Finally, a study using Just in Time Teaching (JiTT) techniques in General Chemistry was performed. This pedagogical approach and its effect on student performance and attrition is discussed. The class involved in the JiTT program was found to have significantly improved student performance and significantly reduced attrition rates in General Chemistry. In conclusion, this dissertation presents and discusses several studies focused on improving student performance and decreasing attrition rates in the first year chemistry curriculum at Texas Tech University.Item On the use of hydrophobic biopolymers and hydrophobic biopolymer-coated sands for the removal of naphthalene, phenanthrene, and pyrene from contaminated sediments(2010-12) Sitzes, Ryan Ziegler; Reible, Danny D.; Lawler, Desmond F.The overall objective of the present study was to evaluate the effectiveness of using a variety of hydrophobic biopolymers and hydrophobic biopolymer-coated sands as technically and economically feasible in-situ sediment amendments or alternative capping materials on a laboratory scale. Cutin from tomato peels, cellulolytic enzyme lignin from sitka spruce chips, and keratin azure from commercially dyed sheeps wool were isolated, prepared, tested, and evaluated as feasible hydrophobic biopolymers for the removal of selected Polycyclic Aromatic Hydrocarbons (PAHs). Testing included chemical and physical characterization, as well as the measurement of kinetics and equilibrium sorption parameters for the sorbates naphthalene, phenanthrene, and pyrene as model hydrophobic organic contaminants. Tomato peel cutin exhibited the largest overall affinity for PAHs, however, keratin azure was selected for further evaluation as the most feasible material due to its low preparation cost. Amendment of industrial sand with a stable, uniform, cross-linked keratin azure derivative was achieved to produce hydrophobic biopolymer-coated sand products containing zero, moderate, and high mass fractions of sand. Chemical and physical material parameters, as well as kinetics and equilibrium sorption parameters for the sorbates naphthalene, phenanthrene, and pyrene, were then obtained for the coated sand products. This allowed simple finite difference modeling of PAH fate and transport through a thin cap comprised of the same, insight into the specific sorption mechanisms involved, and information which could prove useful in predicting potential of keratin products to provide a suitable capping material. Conclusions and recommendations for future research focus on the technical and economical feasibility of the prepared hydrophobic biopolymers and hydrophobic biopolymer-coated sand products as capping or in-situ sediment amendments.Item Session 2F | From Mold Remediation to Collection Digitization(2022-05-24) Mason, MicheliaIn the Fall of 2021, a section of the oldest journals in the Tom Slick Library fell subject to extensive mold. Using interlibrary loan data, OCLC availability, and the PAPR registry, the library staff were able to validate the cost to clean and maintain the entire area. The experience highlighted the value and susceptibility of the collection in full and leads to the prospect of digitization. This reverse workshop aims to encourage a forum of digitization insights, experiences and best practices, grants and potential partnerships to help guide efforts across our organizations.Item Student achievement in developmental mathematics and effective practices in developmental education: a study of an Urban Community College District in Texas(2009-12) Alcorta, Lisa Salinas; Roueche, John E.Success rates for students in developmental education are dismal. The greatest need for developmental education instruction occurs in mathematics, where high numbers of underprepared students generate great concern and the need for substantial changes in higher education institutions. With higher rates of students requiring remediation in the community colleges, the identification of effective policies and practices in developmental education is necessary to increase the achievement rates of developmental education students, and more specifically developmental mathematics students. This study explored the relationship between developmental mathematics student performance and developmental education programs of the Urban Community College District colleges. In addition, this study set out to identify institutional characteristics between colleges whose developmental mathematics students met state mandated academic outcomes at higher rates than their sister colleges.