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Included in this file is a CD drive titled "Chapter Three: Supporting Information" with a 00:40 second long animation. For best quality, view in VLC, not Quicktime Player. / <p>Groundwater contamination by dense non-aqueous phase liquids (DNAPLs ), such as chlorinated solvents, continues to be a significant environmental problem. When released to the subsurface, either due to improper disposal or accidental release, DNAPLs can form complex source zones whose geometry is largely controlled by the geological heterogeneity of the subsurface. These source zones are composed of disconnected, immobile blobs or ganglia trapped by capillary forces (referred to as DNAPL residual) between high-saturation regions located at permeability interfaces (referred to as DNAPL pools). The slow dissolution of DNAPL pools can result in the contamination of groundwater for time periods on the order of decades to centuries.</p> <p>The common conceptual model used in the investigation of DNAPL-contaminated sites is based primarily on the mass transfer from DNAPL to the surrounding aqueous phase in the saturated zone. However, the presence of a discontinuous gas phase above a DNAPL pool can significantly affect the mass transfer from the pool through repeated, spontaneous expansion and mobilization of the gas phase. This mechanism has not been included in the common conceptual models.</p> <p>The goal of this research was to develop a quantitative understanding of discontinuous gas phase expansion and mobilization above a DNAPL pool. This goal was addressed using a combination of small-scale and intermediate-scale laboratory experiments. Small-scale, no-flow vial experiments were used to measure the expansion of single gas bubbles above DNAPL pools, and provide the basis for the development of an analytical model to assess the effect of expansion by multi-component partitioning on the mass transfer from DNAPL pools. Small-scale flow cell experiments were used to measure spontaneous expansion rates in porous media, and provide visual data concerning the distribution of the gas phase. Small-scale air injection experiments were used to characterize the gas flow. Finally, an intermediate-scale flow cell experiment was used to provide larger-scale data concerning the transient distribution of the gas phase, and measure the effect of spontaneous expansion and mobilization on the aqueous-phase DNAPL constituent concentrations.</p> <p>The combined results of these experiments established a detailed conceptual model for the spontaneous expansion and mobilization of a discontinuous gas phase above a DNAPL pool. In this conceptual model, spontaneous expansion of a discontinuous gas phase above a DNAPL pool occurs due to multi-component partitioning, and depends on the concentrations of both the volatile DNAPL and the other dissolved gases. This expansion is more likely to occur, and will be faster, in shallower systems (i.e. lower hydrostatic pressures) containing coarser media (i.e. lower capillary pressures), more volatile DNAPL, and higher concentrations of other dissolved gases (i.e. higher partial pressures). Mobilization of the expanding gas will occur as discontinuous gas flow in most sands, where the repeated trapping and coalescence of gas clusters can allow rapid, large-scale vertical transport of the gas phase. This discontinuous gas flow can produce macroscopic gas fingers composed of multiple, discrete gas clusters. These macroscopic fingers can reach substantial heights above the pool surface, but the growth occurs predominantly at the pool's leading edge due to the stripping of other dissolved gases. This expansion and mobilization can significantly affect the mass transfer from the DNAPL pool if the gas phase is in direct contact with the pool surface; or if the gas phase is close to the pool surface, covers a large fraction of the pool, and the groundwater flow is sufficiently slow. The partitioning of DNAPL constituent from the mobilized gas phase to the aqueous phase well above the pool surface can also change the spatial distribution of aqueous-phase DNAPL constituent concentrations, increasing them above those that are expected based on theoretical calculations for strictly DNAPL-water systems, even at elevations where the concentrations are expected to be zero. The increased concentrations well above the pool surface can appear as short-duration events in the presence of a sustained gas phase, due to the partitioning of DNAPL constituents from the gas to the aqueous phase during multi-component mass transfer. The results of this research provide the necessary basis to begin incorporating this fundamental mechanism into the conceptual and mathematical models used for DNAPL-related research, the investigation ofDNAPL-contaminated sites, and the design and application of DNAPL remediation technologies.</p> / Thesis / Doctor of Philosophy (PhD)

The Deepwater Horizon (DWH) blowout, in the Gulf of Mexico, heavily contaminated miles of sandy beaches. Previous experience of petroleum contamination has shown that oil residues can persist in the sediments for decades. Biodegradation is the major mechanism of remediation regarding petroleum hydrocarbons. There is an urgent need to evaluate the competent indigenous microbial biomass in contaminated sediments if the risks posed by toxic oil residues, for the coastal ecosystem, are to be minimized. We report a field investigation during December 2010 and January 2011 regarding measurement of microbial activity in a sandy beach at the Bon Secour National Wildlife Refuge in Alabama. One transect of wells for sampling was installed in the beach; starting with multiport one, being most landward and thought to be least exposed to oil residue and ending with multiport four being the most seaward and exposed to the open waters of the Gulf of Mexico. Sediment samples were collected from different depths purposely chosen from above, inside, and below the oil layers for microbial analysis. Dissolved oxygen (DO) measurements were obtained and temperature was recorded while collecting the oxygen measurements. Pore water samples were collected for nutrient content and were monitored using the multiport sampling wells. Moisture content was analyzed from the sediments extracted at various depths at each well. pH and salinity were also analyzed for their contributing affect on the microbial community. Grain size distribution analyses were conducted on samples collected at all wells and at multiple depths to characterize the field study location. Results show that the bacterial biomass, as measured by Adenosine-5-triphosphate (ATP) and numbers of alkane and polycyclic aromatic hydrocarbon (PAH) degraders determined by Most Probable Number (MPN), are consistently higher in the sediment layers where oil had been detected. A very good correlation was observed among the relative abundance of bacteria in the different samples using MPN and ATP measurements. As expected, ATP based estimates of the microbial populations were two orders of magnitude higher than the alkane and PAH numbers determined by MPN, which reflect the non-cultivability of most environmental bacteria. The lower concentrations of PAH degraders than alkane degraders that were observed in this study are consistent with other studies, even though both populations are lower than in studies involving fresh oil trapped in beach or wetland sediments. PAHs (aromatics) are notoriously more resistant to biodegradation than alkanes, therefore allowing a lower number of biomass to grow using them. The overall smaller size of the bacterial numbers could be explained by the naturally occurring low-organic content of beach sand. On the other hand, this may be due to the highly weathered nature of the oil or it could reflect some other limitation. / Civil Engineering

The role of aquifer microorganisms in controlling arsenic contamination of Bangladesh aquifers via oxidation of organic carbon coupled with reduction of sedimentary iron oxyhydroxides and concomitant arsenic dissolution is generally accepted. What remains to be ascertained is the in situ biogeochemical mechanisms of cycling different carbon sources and directly relating indigenous microbiota to arsenic release. Using biomarker fingerprint approaches, this dissertation expanded the presently growing research in the biogeochemical carbon cycling controlling arsenic contamination in Bangladesh aquifers. Comprehensive profiles of microbial cell membrane components (PLFA and sterols) at three different aquifers tested the regional distribution of aquifer microbial community abundance, structure, and organic input potential across Araihazar. The highly variable bulk viable microbial biomass observed across these three sites confer both regional-scale and localized heterogeneous distributions of in-aquifer microbial communities which control carbon cycling in the aquifer. The lack of correlation between PLFA biomarkers and dissolved arsenic challenges the assumption that greater extent of microbial community metabolism results in an increase in arsenic in groundwater. Natural abundance radiocarbon isotope Δ14C analysis of cell membrane PLFA and available carbon pools (SOC, DOC, DIC) confirmed that young organic carbon substrates are being cycled at two of the three sites investigated here. This corroborates previous reports at nearby sites (Site B and F) thereby contributing to a well-constrained carbon source which actively support microbial metabolism over a regional scale. Sterol biomarker distributions were characterized to determine potential sources of organic input into the aquifer. In particular, the importance of raw human and/or animal sewage waste as a source of labile carbon was assessed by measuring the faecal biomarker Coprostanol and comparing its abundance to other sources of biogenic sterols using sewage input proxies (Sewage Contamination Index, Coprostanol/Cholesterol ratio). This was motivated by previous findings which correlated sewage contamination with dissolved arsenic at depth at nearby sites. While sewage contamination was low in the shallow aquifers at these sites, it is more likely that plant organic matter supported the elevated microbial abundance at shallow depths. On the other hand, evidence presented in this project suggests that sewage contamination intrudes into deeper aquifers (e.g. buried Pleistocene) and contributes to the vulnerability of previous pristine aquifers to future arsenic contamination. / Thesis / Master of Science (MSc)

Meat and poultry slaughtering and processing practices have been associated with the microbial contamination with Listeria spp. Ready-to-eat poultry products have been considered as a primary agent associated with Listeria monocytogenes illness outbreaks. Developing environmental monitoring programs (EMPs) that are based on product and/or process risk level analysis is a useful approach to reduce contamination in poultry processing plants and enhance food safety. Sampling criteria that is based on product risk levels and process control in ready-to-eat poultry processing facilities was developed to allow users to design and conduct appropriate sampling plans to target Listeria spp. After developing the criteria, an internet-based environmental monitoring program ("EZSafety") was developed to allow poultry producers to enhance their sample collection and analysis of test results over time and conduct appropriate sampling plans for Listeria spp. and other microbiological indicators. The frontend of the program website was built using React Native (an open-source JavaScript library for building user interfaces). The backend of the program website was built using Node.js which executes JavaScript code outside a web browser. MongoDB was used as a document-oriented database for the website. The program was evaluated by 20 food safety professionals to assess its ability to develop appropriate sampling plans to target Listeria spp. The majority of these participants believed that EZSafety has several tools that are effective for targeting Listeria spp. and other indicators and enhancing environmental monitoring. Additionally, most participants agreed that EZSafety is organized and user-friendly. EMPs can play a significant role in improving the detection rate and the prevention of Listeria spp. and other indicators in poultry processing plants. / Master of Science in Life Sciences / Meat and poultry slaughtering and processing practices have been associated with the microbial contamination with a bacterium known as Listeria. Cooked poultry products during the manufacturing process have been considered as a primary agent associated with Listeria monocytogenes (disease causing type of bacteria) sickness outbreaks. Developing environmental monitoring plans to detect and prevent this bacterium in poultry processing establishments is a useful approach to reduce contamination and enhance food safety. Several guidelines and baselines were developed to allow users to design and conduct appropriate environmental monitoring plans to target this bacterium. After developing these guidelines and baselines, an internet-based environmental monitoring program ("EZSafety") was developed to allow poultry processors to enhance their sample collection and analysis of test results over time. The program was developed using several kinds of computer platforms (JavaScript, React Native, and MongoDB) . These open-source platforms were used to design, develop, and store the program over the internet. In order to validate its usefulness, the program was evaluated by 20 users who are majored in food safety and familiar with poultry processing plants hygiene to assess its ability to suggest appropriate monitoring plans. Most of the participants believed that EZSafety has several tools that are effective for targeting Listeria and other kinds of bacteria and enhancing environmental monitoring plans. Additionally, most participants agreed that EZSafety is organized and user-friendly. Such automated monitoring programs can play a significant role in enhancing the detection rate and the prevention of Listeria and other organisms in poultry processing facilities.

The problem of conatmination in culture media for Mycobacterium tuberculosis has not been solved completely, and for this reason the work herein presented was carried out. In this work experiments were made testing the effect of actidione in inhibiting certain ones of the higher fungi.

Yes / Pesticide contamination is a global issue, affecting nearly 44% of the global farming population, and disproportionately affecting farmers and agricultural workers in developing countries. Despite this, global pesticide usage is on the rise, with the growing demand of global food production with increasing population. Different types of porous materials, such as carbon and zeolites, have been explored for the remediation of pesticides from the environment. However, there are some limitations with these materials, especially due to lack of functional groups and relatively modest surface areas. In this regard, metal-organic frameworks (MOFs) provide us with a better alternative to conventionally used porous materials due to their versatile and highly porous structure. Recently, a number of MOFs have been studied for the extraction of pesticides from the environment as well as for targeted and controlled release of agrochemicals. Different types of pesticides and conditions have been investigated, and MOFs have proved their potential in agricultural applications. In this review, the latest studies on delivery and extraction of pesticides using MOFs are systematically reviewed, along with some recent studies on greener ways of pest control through the slow release of chemical compounds from MOF composites. Finally, we present our insights into the key issues concerning the development and translational applications of using MOFs for targeted delivery and pesticide control.

The effects of contaminated supply air on the performance of a laminar proportional amplifier were experimentally investigated. The air supply was contaminated with oil vapor and particulate matter. Characteristic gain curves were obtained after each stage of contamination for various loading conditions. Photographs showing the location of contaminant deposits were taken. Two inlet geometries were studied: right-angle and straightthrough. The effects of maintaining a constant pressure and constant flow rate at the inlet throughout the duration of the tests were studied. Also, aspect ratio effects. were studied. Rapid deterioration of performance was evident with the right-angle entry due to inlet blockage. By milling a cavity in the bottom cover plate, the detrimental effects of inlet blockage were delayed. With constant pressure inlet conditions and straight-through geometry, significant buildup occurred in the nozzle region and downstream. Decrease in pressure recovery was linear with time. It was determined that null shift was caused by asymmetric buildup in either the nozzle region or splitter region. With constant flow inlet conditions, the damaging effects on performance were delayed for both inlet geometries. Also, for the straight-through inlet, the nozzle region was relatively clean when compared with the constant pressure inlet case. Null shift was found to be the result of asymmetric buildup in the downstream region. At lower aspect ratios, the damaging effects of contamination were more severe and occurred in less time. / Master of Science

There is emerging concern about the potential for elevated lead in water after water utilities conduct EPA mandated (or voluntary) partial replacements of existing lead service lines. Connections between dissimilar metals results in the accelerated corrosion of the less noble metal via galvanic attack, increasing metal concentrations in water and posing potential public health risks. Many practical problems associated with stopping galvanic attack between copper:galvanized iron and copper:lead via use of dielectrics have also been raised. Galvanic corrosion can be effectively stopped by isolating the dissimilar metals; however, completely eliminating electrical continuity may not always be practical or allowed by code. Instead, increasing separation distance between the two metals was hypothesized to considerably reduce galvanic corrosion. Galvanic corrosion and lead leaching were evaluated for lead:copper connections with varying separation distances while maintaining electrical continuity. Increased distance between lead and copper pipe dramatically reduced the galvanic current and the magnitude of lead release. Galvanized iron and copper connections were also investigated using various commercial fittings, and results verified that a controlling factor was separation distance between the two dissimilar metals. When considering the long-term behavior of partially replaced lead service lines, detrimental effects from galvanic corrosion worsened with time. Even when water was sampled consistently at moderate flow rate, the condition representing traditional partial service line replacement was 40% worse than a full lead service line. At elevated flowrates, lead concentrations and variability increased for partly replaced lead pipe versus full lead pipe due to reservoirs of lead rust formed via galvanic corrosion. At low flowrates, these negative impacts were not observed. Finally, crevices formed by the use of commercial couplings increased lead release. Overall, the results enhance practical understanding of galvanic corrosion impacts and use of dielectrics in water service lines and premise plumbing. / Master of Science

In many drinking water systems in the United States, disinfectant is added to water as it leaves the plant to maintain a residual concentration in the distribution system. The disinfectant residual is maintained to inactivate contamination that enters the distribution system, to control biofilms, and to act as a sentinel for contamination in the distribution system. A model was developed to evaluate the potential effectiveness of the disinfectant residual at inactivating contamination. The model was used to examine contamination of a hypothetical distribution system through backpressure at a cross-connection under different operating conditions. The dilution and pathway of the hypothetical contaminant were examined as the contaminant moved through the system. Disinfection and inactivation kinetic relationships were used to model the inactivation of the contaminant in the system by the amount of disinfectant present. The model showed that both chlorine and chloramines in each decay and inactivation condition considered provided some benefit over no disinfectant at all when examining susceptible organisms. Chlorine, under medium and low decay conditions, provided the best inactivation. Where 29.8% of total node time steps received a contamination of concern in the absence of disinfectant residual, as low as 4.8% of total node time steps received a contamination of concern in the presence of disinfectant residual. Chloramines was found to persist longer in the distribution system, but resulted in much lower inactivation compared to chlorine. Disinfectant doses typical of common distribution system operation were able to reduce the impact of contamination once it entered the distribution system but, except for four cases, were unable to prevent contamination from spreading within the distribution system. Therefore, it was concluded that presence of a disinfectant residual will reduce the total number of exposure opportunities from a contamination event, but cannot be relied upon to eliminate the chance of exposure resulting from contamination. / Master of Science