The ability of the subsurface microbial population to degrade the major organic contaminants at three sites was assessed. The three sites included an abandoned wood creosoting facility in Conroe, Texas where the silty sand aquifer was contaminated primarily with polynuclear aromatic hydrocarbons; a sandy aquifer in Traverse City, Michigan where a spill of jet fuel polluted the ground water with benzene, toluene, and xylenes; and a site on the Texas Gulf Coast in which the fine sand aquifer was contaminated with benzene, toluene, naphthalene, and bis(2-chloroethyl) ether. Representative subsurface cores and ground water samples were collected for each site and used in the experiments to characterize the microbial population, to determine their ability to degrade the organic contaminants particular to the site, and to ascertain the factors limiting biodegradation of the contaminants at these sites. Laboratory experiments on the Conroe site revealed that the microbial population found in the contaminated zone could degrade the pollutants, but the microorganisms were not acclimated in the uncontaminated areas. The limiting factor at this site was the supply of dissolved oxygen. Field tests and modeling simulations confirmed these results. At the Traverse City site, few organisms were found that could degrade the test compounds in the uncontaminated zone. The microorganisms from the uncontaminated site could not respond as rapidly to a natural substrate as organisms in the contaminated zone which suggests their metabolic status was altered by the contamination. Oxygen, not inorganic nutrients, limited biodegradation at this site although anaerobic degradation of the contaminants may also occur. At the third site, the organisms in the uncontaminated zone were active against benzene, toluene, and to a lesser degree, naphthalene. In the contaminated zone, a toxicant may have reduced the amount of biodegradation occurring. This project demonstrated that microorganisms in the contaminated zones of two sites were active against the contaminants, but were limited in their ability to degrade these contaminants by the supply of dissolved oxygen. At the third site, a toxicant appeared to control biodegradation.

The prevention of scale is an important chemical process in many commercial applications, such as water purification, electricity generation, and chemical production. Scale prevention is especially important in the area of oil and gas production, where scale formation can restrict or completely block fluid flow in a well. One economical way to prevent scale buildup in oil and gas wells is through an inhibitor squeeze treatment, where scale inhibitor chemical is injected into the producing formation. The concentration of inhibitor returning with the brine inhibits scaling. This return concentration is currently unpredictable, because the interaction between the inhibitor and the rock forming minerals have not been quantified. Thus, treatment can neither be controlled, optimized, nor predicted. In the current research, surface complexation, solubility, and phase transformation theory are used to quantify the inhibitor-rock interactions. Solubility and adsorption equilibrium constants of the chemical components in commercial Nitrilotri (methylene phosphonic acid), NTMP, have been determined from laboratory experiments or obtained from the literature. The precipitation and solubility of calcium-NTMP salts were observed to vary with experimental conditions and with extent of aging. This observation was similar to observations made with calcium phosphate precipitation. The equilibrium constants obtained were used to evaluate the chemical conditions in the formation during an inhibitor squeeze at the Texaco N. R. Smith #4 well. Results suggested that $Ca\sb{2.5}HNTMP*2H\sb2O$ and $CaHPO\sb3*1.5H\sb2O$ were in equilibrium with the return brine. The results also suggested that the relative concentration of the chemical components in the commercial product differed in the return brine. The equilibrium constants were also incorporated in a simplified transport equation to simulate the squeeze process. The simulation results suggested that calcite availability may limit inhibitor component precipitation. The results also showed that the adsorption and calcium salt solubility of the inhibitor components could be used to estimate the shape of the return curve.

The effect of electrokinetic phenomena on the performance of ceramic membranes is studied. The results of experiments that evaluate the effects of the ionic strength, pH and the composition of the feed water on the performance of ceramic microfiltration membranes are reported. Theoretical calculations that estimate the electroviscous effect on membrane performance are presented and compared to experimental observations. Experiments were conducted on the membranes with cross-flow filtration mode and dead-end filtration mode. The electrokinetic properties of the membrane and pore surfaces were evaluated. The ionic strength and pH of the feed water are shown to affect membrane permeation behavior. This effect was shown to vary with average pore size, structure and composition of the membrane. Electroviscous considerations were shown to account partially to the observed effects of the feed water chemistry on the permeate flux. The composition of the electrolyte solution and the mobility of the ions in solution were also shown to influence membrane permeation rates. Theoretical considerations indicate that the effect of electrokinetic phenomena were shown to be significant for membranes with high pore surface potential ($\geq-$100 mV) and at intermediate electrokinetic radii, $\kappa$a $\sim$ 2. This condition corresponds to a membrane with a pore radius, a of 0.1 $\mu$m and ionic strength of $2.5\times10\sp{-5}$ M resulting in a Debye parameter, $\kappa$ around $2\times10\sp7 {\rm m}\sp{-1}.$

Uncontrolled discharges of significant volumes of non-aqueous phase liquids such as petroleum fuels and chlorinated solvents have occurred at many sites. Understanding the fate and transport of NAPLs in the subsurface is necessary for assessing the extent and environmental impacts of the contamination, and its remediation. Temperature changes that cause freeze and thawing of soil moisture can result in the alteration of the soil pore structure, which can induce changes in the distribution and morphology of liquid phases present in soil. This study focuses on the effect of freeze-thaw cycles on the volume distribution, morphology and specific surface area of the NAPLs, gasoline and perchloroethylene (PCE) present at residual saturation in porous media. The volume distribution of NAPL blobs in packed sand columns were characterized using a medical X-ray CT scanner. The results show that gasoline blobs were mobilized to a significantly greater extent than PCE blobs. The morphology of the gasoline blobs such as volume, surface area and fractal dimension were also altered more than PCE blobs as a result of freeze and thaw. The extent of mobilization and morphological changes were a function of the freezing rate.

Polycyclic aromatic hydrocarbons and many of their derivatives are considered to be ubiquitous environmental pollutants, which often exhibit mutagenic and/or carcinogenic activity. In the atmosphere, photolysis is generally considered to be the dominant degradation pathway for these pollutants. The photochemical behaviours of benzo(a)pyrene, benzo(b)fluoranthene and benzo(k)fluoranthene have been examined in the laboratory. This study was complemented by an analysis of ambient air samples collected in the vicinity of a Horizontal Stud Soderberg aluminum smelter in Beauharnois, Quebec. Benzo(a)pyrene is much more reactive in the presence of light when compared to the fluoranthene compounds. The products were identified as the 1,6-, 3,6- and 6,12-benzo(a)pyrenediones. An analysis of the ambient air samples revealed the prevalence of benzo(b)fluoranthene in the emissions from the aluminum smelter. Its relatively high abundance and resistance to degradation indicates that it will be a suitable indicator to represent total polycyclic aromatic hydrocarbon levels at the smelter. The photochemical behaviour of a series of nitropolycyclic aromatic hydrocarbons has also been investigated. The photoreactivity of these compounds in solution and adsorbed onto a surface has previously been associated with the torsion angle of the nitro group with respect to the aromatic moiety. Initially, through a combination of spectroscopic techniques and semi-empirical calculations, the orientation of the nitro group in each compound was determined. Solution studies were inconclusive in determining the role of the torsion angle of the nitro group in influencing the photochemical degradation. However, when the compounds were adsorbed onto a surface, no relationship could be established between photoreactivity and the orientation. The stability of these compounds was also examined during the sampling process. In an effort to further examine the relationship between th

Earlier work with pure cultures has shown that the interaction of microbes with plasticizers leads to the formation ofmetabolites including 2-ethylhexanol and 2ethylhexanoic acid that resist further degradation. The same studies have shown that these compounds exhibit acute toxicity. This work has shown that the ability of soil micro-organisms to produce these metabolites from the degradation ofplasticizers is a general phenomenon. It was also found that the ability of soil organisms to degrade 2ethylhexanoic acid does not seem to be as common. Taken together, it would be expected that partial de gradation products of plasticizers should be observed in the environment. This was confirmed in a variety of environmental samples including sediments, surface waters, tap water, and fresh precipitation. Thus, even in a complex ecosystem, when plasticizers were degraded, the breakdown is not complete and significant amounts of2-ethylhexanoic acid and 2-ethylhexanol were observed. Since it is already weIl established that plasticizers are ubiquitous in the environment, it is expected that their recalcitrant metabolites will also be ubiquitous. This is a concem because, while the plasticizers do not exhibit acute toxicity, their metabolites do. / Il a été démontré, lors d'études précédentes faites avec des cultures pures, que l'intéraction de microbes avec des plastifiants mène à la formation de certains métabolites résistant à une dégradation ultérieure, incluant le 2-éthylhexanol ainsi que l'acide 2éthylhexanoïque. Ces mêmes études ont aussi démontré que ces composés ont une toxicité aigue. Le présent ouvrage a démontré que l'habileté à produire ces métabolites à partir de la dégradation de plastifiants est un phénomène généralisé chez les microorganismes provenants des sols. Il a aussi été démontré que l 'habileté de ces microorganismes à dégrader l'acide 2-éthylhexanoïque ne semble pas être aussi répandue. À partir de ces observations, il semble que les produits de la dégradation partielle des plastifiants devraient être observables dans l'environnement. Ceci a été confirmé dans un éventail d'échantillons environnementaux incluant des sédiments, des eaux de surface, des eaux potables municipales et des précipitations. Donc même dans un écosystème complexe, lorsque les plastifiants sont dégradés, la décomposition n'est pas complète et des quantités notables d'acide 2-éthylhexanoïque et de 2-éthylhexanol sont observées. Puisqu'il a déjà été établi que les plastifiants sont omniprésents dans l'environnement, il est prévu que leurs métabolites récalcitrants y seront aussi omniprésents. Ceci présente un intérêt majeur puisque ces métabolites, contrairement aux plastifiants, possèdent une toxicité aigue fr

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Due to industrialization over the past 100 years, the sediments at the bottom of the Lachine Canal and Bay have become contaminated. This study investigated the heavy metal accumulation mechanisms within the Lachine Canal sediments and was carried out in three phases. Laboratory analytical and instrumental work were included. / During Phase I, 28 parameters were measured on 44 samples collected along the Lachine Canal and Bay. The results revealed the presence of a wide variety of both organic and inorganic contaminants. Heavy metals such as Zn $>$ Pb $>$ Cr $>$ Ni $>$ Cu $>$ Cu (in order of decreasing abundance) in addition to organic contaminants (PAH $>$ MAH $>$ PCBs) were found in high concentrations exceeding background concentrations and various quality criteria levels. The total load of both organic and inorganic contaminants was found to be higher in the canal than in the bay zone. Although a positive correlation existed in between % mineral clay fraction or TOC and the total cumulative load of heavy metals, the correlation could not be assessed as conclusive. / Further study on the association heavy metal-sediment constituents (Phase II and III) was carried on the canal zone. X-ray diffraction, Transmission Electron Microscopy and other geochemical analysis revealed that the sediments consisted mainly of silt and clay size fractions composed of: illite, kaolinite and chlorite, calcite and dolomite and minor amounts of Fe- minerals, organic matter and amorphous metal oxides. Each of these constituents bound heavy metals at varying degrees as assessed by a sequential extraction (SE) protocol. The partition distribution pattern was ruled by the geochemical setting. The associations with each phase were (in order of decreasing significance): (1) residual phase Pb (50%) = Cd (50%) $>$ Cr (49%) $>$ Zn (20%), (2) oxide phase Zn (33%) $>$ Pb (32%) $>$ Cr (28%) $>$ Cd (10%), (3) carbonate phase Zn (38%) $>$ Cd (26%) $>$ Pb (13%) $>$ Cr (5%), (4) the organic phase Cr (14%) $>$ Zn (8%) $>$ Cd (6%) $>$ Pb (5%) and (5) the exchangeable phase Cd (8%) $>$ Cr (4%) $>$ Zn (1%) = Pb (1%). The order of abundance in terms of total concentration was 1300 mg Zn/kg, 500 mg Pb/kg, 90 mg Cr/kg and 10 mg Cd/kg. / According to the cation exchange capacity (CEC), carbonate and oxide content measurements, the heavy-metals occupied a minor fraction of the total capacity to retain metals by these mechanisms. The SE results revealed that the partition patterns varied with pH. The phases associated to the carbonate and the exchangeable phases were the most sensitive to a change in pH with the residual phase being almost unchanged. The Zn and Cd were sensitive to release when the conditions drifted to acidic conditions. Towards basic conditions no change in the metal distribution was observed. / The partition patterns for various grain size fractions (${}175 mu$m) revealed that no particular fraction accumulated a certain heavy metal. However, a small increment of heavy metal content with decreasing grain size was found for Zn, Pb and Cd while the contrary was found for Cr. The metal distribution of each grain size fraction followed the pattern under unsieved conditions. / Additionally, it was found that the geotechnical behaviour of sediments was influenced by the chemical composition of the sediments specially with respect to water retention.

The Netherlands is a kingdom known for resisting the perils of natural disaster and keeping records of how these great feats were accomplished. The Dutch have measured physical risk through methods such as the intricate VNK models to predict flood scenarios, but little research has been conducted to examine how the people living in affected areas could be impacted from a natural disaster event. This study employs fine-scale data to construct a social vulnerability index for the 164 districts of the low-lying delta province of Zeeland. The methodology used to measure social vulnerability is built on recent social vulnerability and resilience research that has been conducted in North America, Asia, and Europe. Specific attention is paid to methods used previously and how they can be improved from a statistical standpoint. Factor Analysis of 35 variables selected from the resilience and social vulnerability literature results in nine factors explaining about 72% of the total variance. The factors of vulnerability in Zeeland include Density of the Built Environment and Public Support, Reduced Wealth and Single Households, Infrastructure Accessibility and Career Qualifications, Recovery Capacity and Female Gender, Personal Wealth, Occupation, Residential Quality, Access to Healthcare, and Evacuation Potential. The index is constructed using data for all 35 variables with weight decided by the variance explained by each factor. Relative index scores range from a low social vulnerability score of 0.248 in the district Kattendijk, Goes, to the highest social vulnerability score of 0.458 found in Oudelandse Hoeve, Ternuezen. The highest-scoring districts are located towards the South of Zeeland. Eight of the ten most vulnerable districts located in Terneuzen. The Municipality of Goes contains more low-scoring districts than any other municipality. The majority of low scoring, less vulnerable districts are located on the Central lobe of Zeeland. The results of the social vulnerability analysis provide new insights for policy makers, researchers, and community stakeholders that could be combined with Dutch flood-scenario models to guide planning efforts in the Netherlands to mitigate the damaging impacts of future floods. The study provides an example for adaptation of a social vulnerability index for a fine level of analysis.

Neurodegenerative disorders affect millions of Americans every year. Incidence increases as the human population ages. Parkinsons Disease, a neurodegenerative disorder in the dopaminergic system of the basal ganglia, causes deterioration of movement as the disease progresses. Researchers have attempted to figure out what causes PD and are currently examining it as an environmental disease. This study examined PD as an environmental disease using a multifactorial approach. Methods included 1) utilization of hospital and mortality records in order to investigate a relationship between occupation and PD 2) using ArcGIS 10.2 technology to examine the spatial components of PD 3) conducting Chi-Square tests and other statistical tests in order to determine the validity of the approach. The findings of this study identified that no factor singlehandedly was responsible for increased PD hospitalization or mortality. Furthermore, this study concludes that many factors in combination may contribute to increased PD hospitalization and/or mortality.