More than one billion pounds of plasticizers are produced each year to supply the plastics industry. Some of these plasticizers, particularly phthalates, are suspected endocrine disruptors. However, few studies have been conducted to determine if they are susceptible to biodegradation by naturally occurring bacteria once they are released into the environment. / Six organisms were tested for their ability to grow in the presence of six different industrial plasticizers. Two bacteria, Rhodococcus rhodochrous and Arthrobacter paraffineus, grew well in media containing n-hexadecane and one of the plasticizers. / Fermentations in a 2-liter reactor were performed with Rhodococcus rhodochrous and three plasticizers: bis 2-ethylhexyl adipate, dioctyl phthalate and dioctyl terephthalate. The organism degraded all of the adipate, half of the terephthalate was degraded and the phthalate was degraded slightly. / In these growth studies, the toxicity of the media increased as the organism grew. This trend was linked to the accumulation of metabolites from the partial degradation of the plasticizer. The two major metabolites were identified as 2-ethyl hexanol and 2-ethyl hexanoic acid. The alcohol was only observed part way through the growth in the presence of the adipate. Its concentration decreased as it was oxidized to the acid and it was not present at the end of the fermentation. / The acid was observed for all three types of plasticizers and it was present in high concentrations at the end of every experiment. The nature and pattern of production of the metabolites were consistent with a pathway for the degradation of all three plasticizers by hydrolysis of the ester bonds. / The accumulation of toxic metabolites indicates that biodegradation may not be a solution to reducing environmental impacts associated with plasticizers that have leached into the environment.

Environmental and industrial systems have been investigated using vibrational spectroscopy. These applications were chosen to demonstrate the potential of vibrational spectroscopy as a means of obtaining molecular information from either in-situ or model environments in a rapid, convenient manner requiring minimal sample handling. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigated two systems in the area of environmental chemistry. Using the characteristic CO stretching bands of the Mn(CO)$ sb3$ fragment, methylcyclopentadienyl manganese tricarbonyl (MMT), an additive to Canadian gasoline, was detected on soils treated with gasoline up to twelve months after exposure. Its longevity on and its interaction with different soils and various substrates was studied. A breakdown of the local symmetry of the manganese tricarbonly moiety suggests a Bronsted-type interaction between the soil and the carbonyl ligands of MMT. The uptake by harbour sediments of two tributyltin species used as marine antifouling agents, was also studied using DRIFTS. Water/sediments ratios and salinity were investigated as factors affecting adsorption. A novel infrared cell for probing the gas-phase infrared spectroscopy (HAGIS) cell was used to study the thermal decomposition products of ethylxanthanate-treated sulphide minerals and those of the related ethylxanthate metal complexes. The gas-phase decomposition products from sulphide minerals treated with ethylxante include $ rm CS sb2, COS, CO sb2, CH sb4, SO sb2,$ ethanol and possibly metal xanthates. The relative amounts of the products depend on the type of mineral surface, the temperature and the atmosphere in the cell. Iron, zinc, lead, nickel and copper ethylxanthate complexes were synthesized, and their thermal decomposition products were also studied by HAGIS. The complexes were classified according to the generation of the primary gas-phase decomposition products. Schemes for the produ

<p> Many households in developing countries rely on contaminated and untreated drinking water sources, contributing to gastrointestinal illness and other health risks. Even piped water quality is often unreliable because of poorly-maintained treatment or distribution systems. Household water treatment (HWT) systems aim to enable users to treat their water at the point of use, making it safe to drink. While some HWT options have been successful in improving health in developing countries, low adoption and sustained use outside pilot projects and epidemiological trials remains one of the current challenges with this approach. Furthermore, Quantitative Microbiological Risk Assessment models predict that the health benefits from water quality interventions drop significantly with even occasional consumption of contaminated water. Therefore, to be effective, HWT options need to achieve high user compliance rates and provide safe water reliably. </p><p> I begin my thesis with an interdisciplinary analysis of the field of water, health, and development, followed by a description of my research study site. Using an interdisciplinary research approach, grounded in the local context, I led the development of an ultraviolet (UV) water disinfection system for rural households. This included an iterative process of design and field tests to create a user-friendly system and laboratory research to improve the performance of the technology. I also collaborated with a non-profit organization based in Mexico in the design of an implementation program to support the adoption and consistent use of the UV system. </p><p> Then I present the design and application of a stepped-wedge cluster randomized trial in rural Mexico to evaluate compliance with the implementation program and field efficacy of the UV system. I developed a framework that disaggregates and measures the components of compliance from initial adoption of a safe water practice to exclusive consumption of safe water. I applied this framework to measure compliance across intervention and control groups and to test if additional program components that improve convenience to users can be a cost-effective approach to increase compliance. I present evidence that the implementation program significantly improved compliance with the habit of consuming safe water, when compared to the practice of purchasing water bottled in reusable 20 L containers in the control group. The additional program components proved to be a cost-effective strategy to increase compliance immediately post-intervention, but their impact degraded with time. By analyzing results across different compliance components, I find limitations of the current HWT approach. I present the rational for pilot testing strategies outside the current HWT paradigm, such as expanding a narrow focus on drinking water to making all domestic water safe to drink or switching from a product-based to a service delivery model. </p><p> As a second component of the randomized trial, I present a series of controlled comparisons to evaluate the field efficacy of the UV system using <i> E. coli</i> as a fecal contamination indicator in drinking water. I use an as-treated-analysis to isolate the impact of the system and contrast these results with an impact evaluation of the implementation program led by a research colleague. I also created a drinking water reliability framework to compare potential contamination impacts from different household water management practices and a logistic regression model to assess household risk factors for post-UV-treatment contamination. I show that treating water with the UV system and storing it in 20 L narrow-necked containers, allowed households to significantly improve their drinking water quality and gain access to a more reliable source of safe water. </p><p> In the final chapter I investigate the greenhouse gas (GHG) emissions associated with the use of HWT technologies in Mexico. I do that by carrying out a literature review of existing studies assessing energy use of water treatment technologies; using secondary data to perform a life cycle assessment (LCA) capturing the embedded CO₂ equivalent emissions of individual HWT products; and developing model to calculate a metric of GHG emissions per volume of water used representative of the HWT sector in Mexico. Filtration, ozone, and UV disinfection technologies resulted in similar LCA emissions, while reverse osmosis had emissions five times higher than the average of the rest. I also find GHG emissions of HWT to be 30 times lower than water bottled in 20 L reusable containers. In a context in which mortgage institutions have created green credit mechanisms, this result is useful for expanding financing options for HWT products, which are often more cost-effective than bottled water, but require a higher capital investment. (Abstract shortened by UMI.)</p>

<p> Mountain Lake is one of only two natural lakes in the state of Virginia. The lake's origin has been attributed to either a natural solution-collapse basin, or to a landslide damming the valley of northwesterly flowing Pond Drain, or to a NW-SE trending fracture lineation. The lake is located within the breached northwest limb of a gently plunging anticline, a part of the larger Valley and Ridge physiographic province. In recent years, the lake drained almost completely, exposing the lake bottom and revealing the presence of four sinkhole-like depressions, containing piping holes at their sides and bottoms, at the northeastern and northwestern margins of the lake. This study focuses on the most likely origin of large sandstone blocks present at the northern end of the lake in an area locally referred to as "Rock City", including mapping of the block locations and analyzing the mode and extent of displacement that they have undergone. An additional objective is to investigate the piping potential of the lake-bottom sediment and its role in seepage out of the lake basin causing lake-level fluctuations. </p><p> Mapping of Rock City was conducted by taking GPS readings at the corners of the rock blocks and using ArcMap Software. Investigations of the displacement mode of the rock blocks was done by comparing the measured orientations of principal discontinuity sets, forming the rock-block boundaries, with discontinuity orientations of undisturbed outcrops within the headscarp, using stereonet analysis. Grain size analysis, Atterberg limits, and a compaction-mold permeameter test were used to evaluate lake sediment's susceptibility to piping. </p><p> Field observations and discontinuity data analysis indicate that Rock City is a landslide that dammed the valley of Pond Drain, consequently forming the lake. The primary mode of slope movement involves lateral spreading that is associated with extension occurring along discontinuities. The Tuscarora Sandstone rock blocks comprising Rock City were detached from the scarp face along a northwest-southeast trending joint set and were displaced laterally towards the west. A seismic event appears to be the most likely triggering mechanism for slope movement. </p><p> Laboratory testing reveals that lake-bottom sediment is susceptible to piping, which is the primary mechanism responsible for the formation of the lake-bed depressions and lake-levels fluctuations. Grain size analysis reveals that lake-bottom sediment consists predominantly of fine sand and silt, both of which are highly susceptible to piping. Results of the compaction-mold permeameter test show that the hydraulic gradient at which lake-bottom sediment starts to pipe, the critical hydraulic gradient, ranges between 1 and 10, depending on the density, grain size distribution and cohesive properties of the sediment.</p>

<p>Purdue University was selected as one of 15 universities to participate in a three year Advanced Vehicle Technology Competition (AVTC) called EcoCar2: Plugging Into the Future. The vehicle built by the Purdue team was a Parallel-Through-The-Road Plug-in Hybrid Electric Vehicle (PTTR PHEV). The vehicle utilized a B20 diesel powertrain to power the front wheels, as well as a custom electric drivetrain to power the rear wheels. Using this vehicle during the final year of the competition, the team was successful in placing 4th overall as well as 2nd in the category of Well-To-Wheel (WTW) Greenhouse Gas Emissions. A stock 2013 Chevrolet Malibu was given to all teams in the competition to use as a base vehicle. The Purdue team removed the stock 2.4L gasoline engine of the Malibu in order to make room for the diesel powertrain and switched the stock Malibu rear suspension assembly to that of a 2013 All-Wheel-Drive (AWD) Buick LaCrosse in order to make room for the electric drivetrain. The electric drivetrain utilized a 16.4 kWhr Lithium Ion battery pack, a 103 kW (peak) 45 kW (nominal) electric motor, and the driveline components of a 2013 AWD Buick LaCrosse in order to transfer power to the wheels. Significantcant challenges concerning the custom electric drivetrain during the competition included the design, fabrication, installation and operation of a rear suspension cradle, Energy Storage System (ESS) and a Thermal Management System for the ESS. Computer Aided Drawing (CAD) and Finite Element Analysis (FEA) were used heavily during the design stages of vehicle development in order to give the Purdue team and AVTC competition organizers sufficient confidence to allow the team to build the designs they had proposed. This work describes the design, analysis and fabrication procedures used by the Purdue team in order to create the electric drivetrain used in their vehicle for the EcoCar2 competition.

<p> The basin-fill aquifers of the American Southwest host elevated concentrations of arsenic in groundwater due to the local geology. Limited information is available on arsenic dynamics in semi-arid and arid regions of the world. This study describes arsenic biogeochemistry and mechanisms of arsenic solubilization for a soil profile collected from the surface to the depth of groundwater in the Cache Valley Basin, Northern Utah. </p><p> The first objective was to delineate mechanisms of arsenic solubilization from sediments collected at the study site. Microcosms containing site groundwater and site-oxidized and site-reduced sediments, were monitored over time to observe changes in the solubilization and oxidation state of arsenic and changes in mineral phases of arsenic and iron. The observed solubilization of arsenic was decoupled from iron reduction in the site-oxidized sediments in the presence of native organic carbon, which disagreed with the widely accepted hypothesis that arsenic solubilization is derived from microbial driven reductive dissolution of iron oxides. Carbonate minerals were defined as the mineral phase associated with arsenic that contributed to the arsenic measured in solution. </p><p> The second objective was to determine how altering redox and water conditions down a profile affects arsenic geochemistry and hence solubility. Redox stratification was delineated in two sediment cores based on chemical analyses and visual observation of redox-sensitive parameters. The vadose zone released a considerable amount of arsenic, while the next zone, the carbonate enrichment zone, released the highest concentration of arsenic. Soluble arsenic was exclusively As(V) in the redox transition zone, where As was primarily associated with iron oxides. Solubilization of arsenic was limited in the deeply reduced depletion zone due to the formation of sulfide minerals. </p><p> Lateral resolution of oxidation state and elemental association of arsenic at the micron scale were delineated using synchrotron-based X-ray absorption spectroscopy under Objective 3. The presence of unaltered arsenic sulfides was revealed in the vadose zone, suggesting that arsenic was inputted continuously to the ground surface. From the water table to the deeply reduced depletion zone sediments, arsenic mineral association was dominated by manganese-bearing carbonate minerals and amorphous iron oxides, which are vulnerable to groundwater fluctuation and redox-cycling.</p>

<p> Empowering citizens to comprehend complex environmental issues affecting their daily lives is essential to sustaining a healthy and informed public. The work of many environmental nongovernmental organizations (ENGOs) and institutions of higher education (IHEs) center around helping their stakeholders become informed of, and in turn, better understand complex environmental problems. However, providing individual stakeholders with knowledge about environmental issues that is easily accessible and understandable represents a recurring challenge in today's society. As a result, a gap continues to exist between that which is known about environmental problems and the public's awareness and understanding of those issues. Arsenic contamination of drinking water from privately owned groundwater wells in rural areas of the southwest the United States is one such environmental issue, which is the focus of this research project. </p><p> Results from this study demonstrate that an Internet-based GIS application represents a promising tool for informing stakeholders of selected water quality issues and helping stakeholders comprehend the scope of arsenic found in drinking water in rural areas. Specifically, findings from this research suggest that the interactive environment of an Internet GIS is an easy to use technology that facilitates the visualization of arsenic water quality impairment in an accessible format for stakeholders. Feedback from ENGO and IHE professionals (who were the target population in this study) indicated that an Internet GIS application, such as the one used in this project, represents one method to inform stakeholders of drinking water quality issues. This, in turn, contributes to reducing the gap between known scientific information about environmental issues and stakeholder knowledge of the facts and consequences associated with those concerns. </p><p> Results from this study inform an important initial step in reducing the knowledge gap (i.e., determining ENGO and IHE professionals' perspectives about the value of use of an Internet GIS for engaging with public stakeholders), leading to the subsequent task of ensuring that public stakeholders are aware of the opportunities to use Internet GIS to become more informed about water quality issues. To advance the findings from this project, additional research is needed to further clarify best practices that ENGO and IHE professionals may employ to disseminate an easily accessible Internet GIS for water quality from rural, unregulated sources. Additional need exists to gather and compare the perceptions of stakeholders with the perspectives of ENGO and IHE professionals to best clarify the use of Internet GIS as a tool to disseminate unregulated drinking water quality information to rural water users.</p>

Within the scope of a project funded by the Quebec Ministry of the Environment and Fauna (MEF), alternative wastewater phosphorus removal methods to alum or ferric chloride coagulation were assessed. The most promising technologies were found to be enhanced biological phosphorus removal, treatment plant process optimization and on-line process control. The use of alum sludges from potable water treatment plants appeared promising although it has not yet been widely practised or studied. The MEF therefore decided to retain the process as one requiring further study. / Through batch sorption tests with synthetic solutions, it was found that aluminum hydroxide has a significant sorptive capacity for orthophosphate, condensed phosphate and organic phosphate. The removal of these phosphates was independent of pH between pH 3 and pH 6. The solubility of the aluminum hydroxide was highly pH-dependent. In all the tests, except that with organic phosphate at pH 3.6, the measured soluble aluminum was consistent with solutions saturated with solid-phase Al(OH)$ sb3$. With organic phosphate at pH 3.6, an aluminum-organic phosphate appears to have formed. A theoretical analysis of Al(OH)$ sb3$ and Al(PO$ sb4)$ precipitation showed that phosphate removal is not achieved through Al(PO$ sb4)$ precipitation when dosing with conventional alum, but rather that a mixed aluminum hydroxide phosphate precipitate is formed. / Jar tests performed with full-scale alum sludge and wastewater showed that phosphate is removed by the particulate fraction of the sludge. The removal of reactive phosphate (orthophosphate) decreased with an increase in the storage time of the alum sludge. This decrease was not seen with the non-reactive phosphate. It was therefore suggested that reactive phosphate removal is carried out by adsorption and that non-reactive phosphate removal is performed by a sweep-floc mechanism. (Abstract shortened by UMI.)

Thesis (Ph.D.)--Tufts University, 2000. / Adviser: Stephen H. Levine. Submitted to the Dept. of Civil Engineering. Includes bibliographical references (leaves 259-277). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (M. Ed)--University of Technology, Sydney, 2006.