4-Phenylcyclohexene (4PC), a contaminant released from latex adhesives used to produce carpet, is structurally similar to the ovarian toxicant, 4-vinylcyclohexene (VCH). VCH causes depletion of primary ovarian follicles in mice. Our aim was to determine if the related compound, 4PC, also causes ovarian damage. Groups of B6C3F1 mice were given either: sesame seed oil (vehicle control), 3 mmole/kg 4PC (4PC-3), 6 mmole/kg 4PC (4PC-6), or 6 mmole/kg VCH (positive control), ip, daily for 30 days. Vaginal smears were done daily to determine the stage of estrus. On day 31, the mice were killed and the ovaries were fixed and stained. The numbers of primary and secondary follicles were significantly reduced in the VCH treated mice, but not in 4PC treatment groups. The number of estrous cycles/30 days was significantly reduced in VCH and 4PC-6 treated groups. This study suggests that although the substitution of a phenyl group (4PC) for a vinyl substituant (VCH) on the cyclohexene ring appears to eliminate the follicular loss, monitoring of the estrous cycles may be an early indication of an adverse reproductive effect for 4PC.

Colloid filtration theory was utilized to estimate the sticking coefficient (α) of bacteria in filter media. Determination of bacterial cell numbers was facilitated by incorporation of [³H] leucine into cells prior to filtration. Large changes in retention of bacteria within porous material correlated with different stages in the bacterial growth cycle. This was due primarily to changes in cell size and not due to a change in α. The effects of ionic strength, pH, nutrient status, surfactant concentration and filter material on α were also evaluated. Various filtration models predicted similar trends in the magnitude of bacterial α with changes in experimental conditions. Experiments were performed with two gram negative and one gram positive bacterial species, Pseudomonas fluorescens, Pseudomonas JS6, and Bacillus pumilus. Small reductions in α were observed in cultures that were carbon-limited. Oxygen limitation produced no change in alpha. Bacterial α's were a function of ionic strength and filter material.

In this study volatile organic compounds (VOCs) emitted during carpet installations employing water-based adhesives were characterized. The potential impacts of 4 adhesives on indoor air quality were evaluated. Headspace sampling and analysis by gas chromatography/mass spectrometry were used to qualitate VOC emissions. Adhesives and carpet/adhesive composite samples were prepared for quantitative analysis of VOC emissions by gas chromatography with flame ionization detection. Volatiles were concentrated using a monitoring device and collected on charcoal adsorption tubes. Sampling intervals ranged from 30 minutes to 21 days. The adhesives emitted primarily aromatic, alicyclic and aliphatic compounds as toluene, m-xylene, 1,2-dimethylcyclohexane, alpha-pinene, 2-methylheptane, octane, nonane, decane and undecane. Emission profiles depended on performance characteristics and manufacturer. A carpet boundary layer slowed VOC decay by acting as a sink. Potential overexposure within 24 hours to specific and total VOCs was indicated for one of the adhesives. This study suggests that water-based carpet adhesives are a potential source of indoor air pollutants.

This study was conducted to determine emission rates of nitrous oxide (N₂O) gas from arid region locations. Fluxes were measured at an effluent-irrigated turfgrass location in Arizona, a Sonoran desert location, and a savannah location in Africa. Fluxes were measured by a closed chamber method at the Arizona locations on a weekly basis during the summer of 1991, and at the African location during two separate three day studies during the summer of 1992. Soils were sampled at each location during each sampling period and analyzed for water content, nitrate, pH, and total organic carbon content. Nitrous oxide fluxes in Arizona averaged approximately 13 and 0.7 kg N₂O-N ha⁻¹ yr⁻¹ for the turfgrass and desert locations respectively. The average fluxes from the African sites were 1.3, 1.6, and 1.3 kg N₂O-N ha⁻¹ yr⁻¹ for a millet field, fallow field, and "tigerbush" plateau, respectively. Diurnal and seasonal variability was observed.

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.

Increased incidences of toxigenic cyanobacterial blooms in freshwater bodies pose significant threats to human and ecosystem health worldwide. Microcystins (MCs), produced mostly by Microcystis, Anabaena, and Planktothrix spp., are amongst the most prevalent freshwater cyanotoxins. Characterization of toxigenic blooms by conventional microscopy is often challenging because of co-occurrence of morphologically indistinguishable toxic and non-toxic strains of cyanobacteria. This research project therefore sought to develop and evaluate polymerase chain reaction (PCR) approaches for improved monitoring of toxigenic cyanobacteria in Canadian freshwater lakes. Preliminary studies evaluating the utility of a suite of microcystin synthetase (mcy) genes for quantitative PCR-based detection of microcystin-producing Microcystis revealed that assays targeting portions of the mcyA, mcyE, and mcyG genes successfully estimated potential microcystin-producing Microcystis genotypes in water samples collected from Baie Missisquoi (Missisquoi Bay), Quebec. The qPCR-based Microcystis mcyA, mcyE, or mcyG toxigenic cell equivalents showed significant associations (p<0.05; R2>0.90) with total Microcystis counts determined by microscopy. Furthermore, all three assays successfully quantified potentially toxic Microcystis cells in samples with undetectable microcystin concentrations, suggesting their potential usefulness in early warning systems for toxigenic cyanobacteria. To further ascertain the utility of developed molecular assays in estimating toxigenic Microcystis concentrations, laboratory studies were conducted to investigate how mcy gene concentrations and biomass of mixed assemblages of a toxic Microcystis sp. and non-toxic Anabaena sp. varied under different nitrogen, phosphorus, temperature, and light regimes. Results demonstrated dependence of growth rates, microcystin cellular and mcyE gene quotas not only on nutrients and temperature conditions, but also the presence of competing cyanobacteria. The fact that changes in mcyE copies often mirrored changes in M. aeruginosa CPCC 299 cellular growth rates implied possible coupling of mcyE production to cellular growth; thus validating use of mcyE gene concentrations as indicators of toxigenic Microcystis.The third phase of this study involved development and utilization of a multiplex qPCR approach for simultaneous quantification of microcystin-producing Anabaena, Microcystis, and Planktothrix genotypes in Missisquoi Bay. Laboratory evaluation showed the multiplex assay to be highly sensitive and specific for mcyE-containing Anabaena, Microcystis, and Planktothrix genotypes, with assay standards achieving R2 values above 0.99 and reaction efficiencies greater than 90%. Analyses of water samples from Missisquoi Bay showed Microcystis spp. as the main putative microcystin producer, with patchy occurrence of toxigenic Anabaena and Planktothrix genotypes during the 2010 and 2011 sampling periods.Finally, the developed qPCR assays were utilized to study Microcystis and Planktothrix mcyE gene expression, concomitantly with changes in mcyE copies, cyanobacterial biomass and MC concentrations, in order to derive the most reliable indicator of microcystin risk. McyE transcripts were generally lower in mixed cultures relative to monocultures, in agreement with depressed growth recorded in the mixed cultures. Whereas concentrations of mcyE gene copies, cell counts, and chl-a correlated significantly (p<0.01) with microcystins in laboratory cultures, McyE gene transcripts levels associated very poorly with MC. Furthermore, mcyE copies showed the strongest positive association with MCs in field samples, suggesting that mcyE copies are better indicators of MC risks rather than McyE transcripts or traditional biomass proxies. / L'occurrence très fréquente d'efflorescences en eau douce constitue une importante menace à la santé humaine et environnementale. Les microcystines sont les cyanotoxines les plus communes et la caractérisation microscopique d'efflorescences toxigènes pose souvent un défi. Ce projet de recherche vise à développer et évaluer des approches axées sur l'amplification en chaîne par polymérase (ACP) pour améliorer le suivi des cyanobactéries toxigènes dans les lacs d'eau douce du Canada. Des études préliminaires évaluant l'utilité, dans la détection quantitative par ACP (qACP) de souches de Microcystis actives ou inactives en production de microcystine, d'une série de gènes codant pour les sous-unités de la microcystine synthétase (mcy), démontra que les tests visant l'identification d'une portion des gènes mcyA, mcyE, ou mcyG permit l'estimation de la quantité de souches de Microcystis toxigènes dans des échantillons d'eau de la Baie Missisquoi, Québec. Les équivalents en cellules de Microcystis toxigènes pour les gènes mcyA, mcyE, ou mcyG furent fortement associés (p<0.05; R2>0.90) au compte total de Microcystis obtenu par microscopie. De plus, les trois tests réussirent à quantifier les cellules de Microcystis ayant le potentiel d'être toxigènes dans des échantillons ayant une teneur en microcystine indétectable, laissant présager leur utilité potentielle dans un système d'alerte précoce pour les cyanobactéries toxigènes. Afin d'évaluer l'utilité des tests moléculaires élaborés pour estimer la teneur en Microcystis toxigènes, des études en laboratoire furent entreprises afin d'évaluer comment la teneur en gènes mcy et la biomasse de différents assemblages mixtes d'une espèce toxigène de Microcystis et d'une espèce non-toxigène d'Anabaena pourraient varier sous divers régimes d'azote, de phosphore, de température et de lumière. Les résultats démontrent une dépendance des taux de croissance, quotas en microcystine cellulaire et gène mcyE sur les nutriments et conditions de température et sur la présence de cyanobactéries compétitrices. Les changements dans le nombre de copies de mcyE furent souvent le reflet du taux de croissance de M. aeruginosa CPCC 299, ce qui implique un jumelage entre la production de mcyE et la croissance cellulaire.L'étude développa et adopta une approche qACP multiplexe pour la quantification simultanée des génotypes d'Anabaena, Microcystis, et Planktothrix produisant de la microcystine dans la Baie Missisquoi. En laboratoire, le test multiplex s'avéra très sensible et spécifique aux souches d'Anabaena, Microcystis, et Planktothrix portant le gène mcyE. Les valeurs de R2 pour la courbe d'étalonnage excédèrent 0.99, et les efficacités de réaction excédèrent 90%. L'analyse des échantillons souligna que Microcystis spp. était le principal présumé producteur de microcystine durant les périodes d'échantillonnage de 2010 et 2011. Enfin, les tests qACP développés servirent à l'étude de l'expression génique de mcyE dans Microcystis et Planktothrix, en parallèle au changement du nombre de copies de mcyE, la biomasse cyanobactérienne et les concentrations en microcystine, afin d'en dériver un indicateur fiable du risque associé à la microcystine. Les produits de transcription de mcyE furent généralement moins élevés dans les cultures mixtes (vs. monocultures), ce qui s'accorde avec la diminution du taux de croissance en cultures mixtes. Lorsque, en cultures maintenues en laboratoire, les concentrations en copies du gène mcyE, le nombre de cellules, et la teneur en chlorophylle a étaient significativement corrélés (p<0.01) avec la teneur en microcystine, le niveau de transcriptions du gène mcyE s'avéra faiblement corrélé au niveau de microcystine. Dans les échantillons, le nombre de copies de mcyE montra une forte association à la teneur en microcystine, suggérant que le nombre de copies de mcyE pourrait être un meilleur indicateur du risque de contamination en microcystine.