<p>Volatile organic compounds (VOCs) are a family of chemicals which are known to have adverse effects on climate change and health, and thus emissions of VOCs are regulated. One such control method is via biodegradation in a biofilter and other similar reactors. Many hydrophobic VOCs, however, are difficult to degrade in such devices. Biphasic bioreactors are designed to remove and treat hydrophobic compounds from waste gas streams. In addition to the water phase, a biphasic bioreactor includes a secondary (2°) liquid phase where hydrophobic VOCs are absorbed and made available for degradation by bacteria. A viable 2° phase is non-miscible with water, non-toxic to bacteria in the bioreactor, and has a strong affinity for target pollutants. In this work, methods were explored by which candidate 2° phases may be screened for suitability to treat two commonly studied hydrophobic VOCs, toluene and hexane. 2° phases included the commonly used silicone oil, paraffin oil and several ionic liquids (ILs), a novel type of solvent popular with the chemical industry. The air-liquid partition coefficient of toluene and hexane with each 2° phases was determined. Additionally the effect on the oxygen uptake rate (OUR) and cell growth in a flask of each 2° phase on biological cultures enriched on toluene and hexane was studied. It was determined that OUR is a poor method of screening 2° phases for biophasic bioreactors. Additionally, cell growth studies failed to capture accelerated degradation of the target pollutants in biphasic cultures. The presence of ILs resulted in significant biological inhibition, and thus do not appear to be promising 2° phase candidates for biodegradation purposes.</p> / Thesis

Groundwater-surface water interactions can substantially influence the quality of surficial water bodies and are thus important when investigating ecological health of and climate change impacts on an area. However, data collection can be hindered when the location is remote and/or legally protected. This paper presents a methodology to implement minimallyinvasive field techniques at a remote and protected location that allows preliminary identification of the relationship between groundwater and surface water. Great Smoky Mountains National Park was selected as the study area as it is subjected to some of the highest rates of acid deposition in the country. Ecological damage is evident in several areas, including Ramsay Prong, a typical fourth-order stream located on the Tennessee side of the park. Ramsay Prong is evaluated on the basis of discharge, water quality, geochemistry, and stable isotopes at six points along the channel. It should be noted that increasing drought conditions occurred in the basin over the course of this study, providing an opportunity to evaluate the situation of low baseflow. Results indicate that storage capacity in the headwaters is insufficient to supply typical baseflow volume during extended dry periods, whereas sufficient alluvium exists at the bottom of the catchment to capture and recharge the basin water supply. A shallow fracture network likely provides long flowpaths for water to travel toward the basin bottom. Furthermore, baseflow is supplied by interflow as well as shallow groundwater storage; the portion of baseflow comprised by interflow increases with increasing antecedent precipitation. Diffuse groundwater recharge occurs mainly in the headwaters where steep slopes dominate the topography, while focused recharge occurs in bedrock depressions within the reaches and at the end of the channel. These observations, coupled with geochemical and isotopic data, indicate that neutralization of acidic inputs is best accomplished in the lower elevations of the basin. It is recommended that future studies investigate the ecological impacts of reduced precipitation in terms of acid neutralization capabilities along Ramsay Prong.

Episodic stream acidification occurs as storm events temporarily reduce acid neutralizing capacity and pH. Stream acidification is suspected to have damaging effects on the health of aquatic ecosystems and biota and is dependent on various watershed characteristics such as drainage area, elevation, slope, and surficial geology. Here, a stochastic modeling approach is applied to continuous pH data for multiple stream monitoring sites within the Great Smoky Mountains National Park in order to characterize episodic acidification responses during stormflows for different streams. The approach summarizes voluminous pH data recorded by water quality sondes at 15-minute intervals into concentration-duration-frequency relationships. Unique to this study is the ability to characterize the episodic acidification response to watershed attributes without using baseflow or single-point stormflow measurements. A slope metric of mean pH event duration, a measure of episodic acidification response was determined to correlate with basin area and elevation. In contrast, baseflow studies have shown elevation to be the main driver of chronic acidification. It appears that during stormflows transport and flushing of stored anions and cations govern the response of streams included in this study.

Thesis (M.App.Sc.) - Carleton University, 2009. / Includes bibliographical references (p.123-125). Also available in electronic format on the Internet.

For perhaps eleven months of the year, surface water flow in the Santa Cruz River consists entirely of wastewater effluent from the Roger Road Wastewater Treatment Plant (RRWTP) and the Ina Road Water Pollution Control Facility (IRWPCF). Like other conventional plants that treat primarily domestic wastewater, effluents from the RRWTP and IRWPCF contain numerous trace organic contaminants--an unintended consequence of our reliance on water to carry waste from points of generation to central treatment facilities. The fates of these compounds in the environment are not entirely clear since the instruments necessary to measure process-dependent changes in concentrations at levels relevant to environmental health are just now coming into widespread use. Chemical fate during planned or incidental infiltration and transport to points of recovery is therefore relevant to the quality of delivered water, as water and contaminants are transported in surface waters and unintentionally reused. Interventions that reduce human and environmental exposures to contaminants present in this water, including natural processes, are thus important to protect human health. Here, it is hypothesized that there is a reasonably continuous discharge of trace organics from wastewater treatment effluents to the Santa River. Because the river is effluent dependent, and travel times can be determined from gauging station flows, some measure of fate and transport of trace organics in the surface water can be obtained. The relative levels of trace contaminants in wastewater treatment plant effluent and downstream waters will provide compound specific attenuations due to dilution with native ground water, sorption on sediments, biodegradation, etc. If destructive mechanisms can be distinguished from dilution, the resultant analysis will be of general interest--an indication of the combination of travel distance and time of travel that is necessary to protect the public when recovered water is eligible for unrestricted potable use without additional treatment. Primary Objectives. *To measure the time-dependent changes in trace organic composition of Santa Cruz River water. *To determine if correlations between known quantities such as biodegradation can be correlated to compound attenuation or persistence during travel. *To apply conclusions from the Tucson data set to other location where dilution and time of travel are also contributing factors; Austin TX and Boston MA. In Tucson, the data suggests that relatively biodegradable compounds are removed by natural processes on a time scale of hours. In areas where dilution and time of travel differ from the Tucson area; such as the Boston area, greater transport distances and times of travel in the Charles River (Boston area) resulted in natural attenuation of most compounds measured, suggesting that even biochemically persistent compounds such as carbamazepine, TCEP and sulfamethoxazole are attenuated to a degree during in-stream transport over periods of days to weeks. The mechanism(s) for these removals is not clear, and the effects of dilution from tributaries are uncertain despite efforts to account for those flows. The limited data from a dry period in a short stream reach in the Little Colorado River (Austin), which was also analyzed, generally support this picture. With one or two exceptions (e.g. DEET), there is limited evidence of compound attenuation between the two proximate monitoring points. Overall, the data indicate that natural mechanisms can be counted on to biochemically degrade or physiochemically transform many of the trace contaminants that are added to surface streams in municipal wastewater effluents. Time scales for compound disappearance range from hours (for relatively biodegradable compounds) to weeks. Although none of the contaminants reported on here is now subject to US federal drinking water regulations, the human health effects of long-term chronic exposure to multiple trace organic contaminants at sub-ppb levels remain uncertain. Environmental impacts are generally acknowledged. Cost effective risk management due to trace organic exposure may eventually include reliance on natural attenuation during in-stream transport to downstream points of reuse.

Engineered nanomaterials are increasingly used in a variety of industrial processes and consumer products. Numerous studies have reported toxicity of different NPs during the last years. Thus, there are growing concerns about the potential impacts to the health and environment of engineered nanoparticles (NPs). However, some methodological problems complicate the interpretation of nanotoxicity studies. On the one hand, some NPs have shown to interfere with classical toxicity assays based on colorimetric or fluorescent measurements. On the other hand, most NPs tend to aggregate in media used in toxicity tests, which complicates the interpretation of the toxicity results. The first objective of this dissertation was to evaluate a novel impedance-based and label-free real time cell analyzer (RTCA) as a high throughput method for screening the cytotoxicity of nanoparticles and to validate the RTCA results using a conventional cytotoxicity test (MTT). Several inorganic NPs were tested for potential cytotoxicity to human bronchial epithelial cells (16HBE14o-). In general, there was a good correlation in cytotoxicity measurements between the two methods. Moreover, none of the NPs tested showed interference with the impedance measurements performed by the RTCA system. The results demonstrate the potential and validity of the impedance-based RTCA technique to rapidly screen for NP toxicity. The second objective of this dissertation was to assess the toxicity of different inorganic NPs to the eukaryotic cell model Saccharomyces cerevisiae, and to test the influence of NP aggregation state in their toxicity. Nanotoxicity was assessed by monitoring oxygen consumption in batch cultures and by analysis of cell membrane integrity. Mn₂O₃ NPs showed the highest inhibition of O₂ consumption and cell membrane damage, while the other NPs caused low or no toxicity to the yeast. Most NPs showed high tendency to aggregate in the assay medium, so a non-toxic dispersant was used to improve NP stability. In contrast to aggregated CeO₂ NPs, dispersed CeO₂ NPs showed toxicity to the yeast. However, dispersant supplementation decreased the inhibition caused by Mn₂O₃ NPs at low concentrations, which could indicate that dispersant association with the particles may have an impact on the interaction between the NPs and the cells. The proven toxicity of some NPs raises concerns about their environmental fate. Municipal and industrial wastewaters are considered primary sources of NPs to the environment. However, information on the behavior and impact of NPs on wastewater treatment processes is very limited. A third objective of this dissertation was to evaluate the fate and long-term effect of ZnO and CuO NPs during wastewater treatment in high-rate anaerobic bioreactors. Laboratory-scale upflow anaerobic sludge blanket (UASB) reactors were fed with synthetic wastewater containing NPs for extended periods of time (>90 d). Extensive removal (62-82%) of ZnO and CuO NPs was observed during wastewater treatment in the UASB reactors. Scanning electron microscopy and chemical analysis confirmed that NPs were associated with the anaerobic sludge. While short-term exposure to low levels of ZnO and CuO NPs only caused minor inhibition to methanogenesis, extended exposure to NPs accumulated in the sludge bed led to a gradual and partial inhibitory response in the reactors. The inhibitory effect was also evident in the decline in the acetoclastic methanogenic activity of the biomass.

The catalytic dehalogenation of tetrachloroethylene (PCE) occurs via oxidation or reductive hydrodechlorination. Catalytic oxidation uses oxygen to dehalogenate PCE into CO₂ and Cl₂. This process requires higher temperatures >350°C then reductive hydrodechlorination and can produce undesirable toxic products, such as dioxins and furans. Hydrodechlorination uses a reductant to reduce PCE to ethane, and intermediate products such as less chlorinated hydrocarbons. Catalyst deactivation and associated loss of activity are commonly observed. Here, we examined a redox environment for the destruction of PCE on commercially available and laboratory made precious metal loaded catalysts. When a mixture of PCE, oxygen and hydrogen are passed over the catalyst, the PCE is converted to ethane, CO₂, water, and HCl as a function of temperature (ambient to 450°C) and hydrogen to oxygen ratio in the feed (0 to 5). In the laboratory experiments, high conversion of PCE was observed for relatively high H₂/O₂ ratios (84% conversion with H₂/O₂ = 2.15, 63% with H₂/O₂ = 1.18 at 350°C, for commercial catalyst) for retention time of ~ 1 s. The conversion of PCE generally increased with increasing temperature for all H₂/O₂ ratios. In the strictly oxidation environment (H₂/O₂ = 0), PCE conversion was lower than with hydrogen at any given temperature (<30% at 464°C). At lower temperature (<350°C) the dominant carbon-containing product was ethane, under redox conditions. At high temperature (>380°C) CO₂ eluted from the reactor, suggesting that oxidation of reduction products or PCE occurs. Experiments were conducted by using a laboratory made catalyst. A mixture of three types of precious metals (Pt, Pd, and Rh) was impregnated onto a monolithic alumina support. These studies show no apparent performance difference between the two catalysts at high temperatures (>280°C). However, at low temperatures the laboratory catalyst outperforms the commercial catalyst. It was speculated that this difference due to high metal loading of the laboratory catalyst (38.61 mg versus 1.27 mg). A field scale study of the commercial catalyst was undertaken at the Superfund Park-Euclid site in Tucson, Arizona, where the soil is contaminated with PCE and other volatile hydrocarbons. Gases from a soil-vapor extraction unit were fed to the reactor, Even though the soil vapor contained high oxygen (>17%), high PCE conversion with and without hydrogen was observed. Due to the relatively high cost associated with the use of hydrogen, propane, methane, and diesel were investigated as replacement reductants. The results indicate that propane and diesel are promising replacements for hydrogen that deserve further investigation.

AbstractArsenic (As) contamination of groundwater and surface water is a worldwide problem. Exposure to arsenic in drinking water is an important current public health issue. Arsenic is well known for its carcinogenic and teratogenic effects. The U.S. Environmental Protection Agency (USEPA) has recently enacted a stricter drinking water standard for arsenic that lowers the maximum contaminant level (MCL) from 50 to 10 ug l-1.Localized elevated As concentrations in groundwater or surface water have been attributed to the natural release of As from the weathering of As bearing minerals. Microbial reduction of arsenate (As(V)) to arsenite (As(III)) and ferric (hydr)oxides to Fe(II) is hypothesized to be the dominant mechanisms of As mobilization in subsurface environments. If oxidizing conditions can be restored, As can be immobilized by the formation of As(V) and ferric (hydr)oxides. As(V) is more strongly adsorbed than As(III) at circumneutral conditions by common non-iron metal oxides in sediments such as those of aluminum. Ferric (hydr)oxides have strong affinity for both As(III) and As(V) in circumneutral environments. Oxygen can be introduced into the anaerobic zone by injection of gaseous O2 to promote oxidation reactions of As(III) and Fe(II), but O2 is poorly soluble and chemically reactive and thus difficult to distribute in the subsurface. Nitrate or chlorate can be considered as alternative oxidants with advantages over elemental oxygen due to their high aqueous solubility and lower chemical reactivity which together enable them to be better dispersed in the saturated subsurface.The objective of this study is to evaluate the importance of anoxic oxidation of As(III) to As(V) by anaerobic microorganisms such as chemolithotrophic denitrifying bacteria and chlorate respiring bacteria in the biogeochemical cycle of arsenic. This study also investigated a arsenic potential bioremediation strategy based on injecting nitrate or chlorate into contaminated groundwater and surface water under anaerobic conditions.In this study, denitrification or chlorate reduction linked to the oxidation of As(III) to As(V) was shown to be a widespread microbial activity in anaerobic sludge and sediment samples that were not previously exposed to arsenic contamination. The biological oxidation of As(III) utilizing nitrate or chlorate as sole electron acceptor was feasible and stable over prolonged periods of operation in continuous-flow anaerobic bioreactors. Evidence for the complete denitrification was demonstrated by direct measurement of N2 formation dependent on As(III) addition. Also complete chlorate reduction to chloride was attributable to the oxidation of As(III). A 16S rRNA gene clone library characterization of enrichment cultures indicated that the predominant phylotypes responsible for As(III) oxidation linked to denitrification were from the genus Azoarcus and the family Comamonadaceae. A bioremediation strategy was explored that is based on injecting nitrate to support the microbial oxidation of Fe(II) and As(III) in the subsurface as a means to immobilize arsenic. Two models were utilized to illustrate the mechanisms of As removal.1) Sediment columns packed with activated alumina were utilized to demonstrate the role of nitrate in supporting microbial As(III) oxidation and arsenic mobility in anoxic sediments containing mostly non-iron oxides;2) Sand-packed columns were used to simulate natural anaerobic groundwater and sediment systems with co-occurring As(III) and Fe(II) in the presence or absence of nitrate. Microbial oxidation by denitrifying microorganisms lead to the formation of ferric (hydroxides) which adsorbed As(V) formed from As(III)-oxidation.The studies presented here demonstrate that anoxic microbial oxidation of As(III) and Fe(II) linked to denitrification significantly enhance the immobilization of As in the anaerobic subsurface environments.

During the past decade, estrogenic contaminants and polybrominated diphenyl ethers (PBDEs) received more and more attention due to their adverse effects as endocrine disruptors. There is a need to examine fate of these contaminants during wastewater treatment and effluent polishing process, as well as during the land application of biosolids as soil amendments, within the context of potable water reuse and sludge application, which have all been widely practiced.Two major research goals guided this research. The first goal was to develop experimental protocols measuring estrogenic activity (including nonylphenol) and PBDEs in environmental samples, especially in organic rich solid samples such as sludges, sediments and soils which are impacted by wastewater and/or application of biosolids. The second objective was to evaluate fate of estrogenic activity and PBDEs during conventional wastewater treatment, effluent polishing, and sludge handling processes including digestion, dewatering, composting, and land application of biosolids by using the protocols developed.The protocol developed to measure estrogenic activity or PBDEs in the solids includes extraction, cleanup, and determination steps. Each step is critical for the successful determination; however cleanup step was the most difficult. In this study, a C18 resin was used as the media to remove the bulk organic interferences in the measurement of estrogenic activity and nonylphenol. In comparison, Florisil was used in the cleanup step for PBDE analysis. In the development of each protocol, mobile phase was carefully selected and optimum cleanup strategy was determined, recovery of analytes during cleanup operation was measured. During the development of method measuring the estrogenic activity, effects of extraction variables such as solvent, pressure, and time were investigated. The performance of each protocol was examined by spike and recovery experiments.Experiments indicated that estrogenic activity and nonylphenol were largely removed during traditional wastewater treatment, soil aquifer treatment, and surface transport along a wastewater dependent stream. Examination of estrogenic activity and nonylphenol in sludge, sediments in contact with wastewater and mass balance analysis of these estrogenic contaminants in traditional wastewater treatment plants and infiltration basins indicated that both adsorption and biodegradation play important roles. In comparison, estrogenic activity and nonylphenol were persistent during anaerobic sludge digestion. More experiments are warranted to understand fate of PBDEs during sludge digestion process, although limited data show possible degradation.

Timing and duration of magmatism, involvement of fluid or assimilation of material, and geodynamic context are all important when assessing the processes by which silicic magmas are produced, erupted, or emplaced. This research relies heavily on in situ analyses of zircon, in combination with whole rock elemental and isotopic data, to investigate the causes and effects of silicic magmatism in two very different contexts. First, in situ age and trace element analyses of zircon from ore-bearing porphyry dikes at Yerington Copper Mine, NV reveal a progressive drop in oxidation state over the ~1 Myr the dikes formed. Unlike previous studies which have found a correlation between bulk rock Cu content and oxidation state as measured by Eu and Ce anomalies in zircon from porphyry Cu systems, no correlation was found at Yerington. In addition, chemical abrasion treatment of zircon, which has been shown to improve age resolution, does not significantly change trace element or oxygen isotope compositions in zircon. Second, this research uses in situ zircon U-Pb geochronology, trace element, and O and Hf isotope analyses in addition to whole rock elemental and isotopic data to evaluate the petrogenesis of multiple extinct silicic magmatic systems in Iceland and the role tectonism plays on their formation. Major findings are: 1) Involvement of hydrothermally altered, low-δ18O material prior to zircon crystallization in silicic systems in Iceland is ubiquitous; 2) A combination of partial melting of Icelandic crust and fractional crystallization of those melts and/or fresh mantle melts produce the vast majority of silicic units studied; magmas produced via pure partial melting or fractional crystallization are rare; 3) Rare calc-alkaline rocks at Króksfjörður volcano have distinctly different whole rock Pb, Nd, and Hf and in situ zircon Hf isotope compositions than coeval tholeiitic units, implying different petrogenetic mechanisms operated simultaneously for ~1 Myr; 4) Longevity of silicic magmatic systems in Iceland is strongly tied to rates of rifting.