Uranium (U), as the uranyl ion (UO22＋), is a widely distributed contaminant at several Department of Energy (DOE) sites, former war zones, and across the globe. Although many U remediation efforts depend on U-bacterial interactions, little information regarding U-bacterial interactions resolved at the molecular level exist. In this study, experiments were performed aimed at understanding the effect of molecular UO2 2＋ speciation on bacterial bioaccumulation and toxicity using an environmental Pseudomonas sp. isolate. Results showed that the charge and stability of UO22＋ species largely controlled the extent of UO22＋ bioaccumulation and UO2 2＋ toxicity, respectively. Further experimentation, including a combination of in vivo, in vitro, and in silico studies, revealed a specific mechanism of UO22＋ toxicity, the first to be reported. This mechanism involves the binding of UO2 2＋ to pyrroloquinoline quinone (PQQ), a cofactor present in a number of bacterial dehydrogenase enzymes. Based on the specific binding mode of UO22＋ to PQQ, it is hypothesized that the present work has direct implications for UO22＋ inhibition of flavoproteins, potentially extending the application of the findings of this work to eukaryotic systems. Recent trends suggest that U-related activity will increase in the near future, and therefore understanding fundamental interactions between UO22＋ and living systems is both an environmental and human health imperative.

Sodium chloride solutions have been used extensively to model seawater in both theoretical and experimental studies of the surface composition and chemistry of atmospheric aerosols. The prediction of the presence of chloride at the liquid-vapor interface has been particularly important for heterogeneous reactions involving the formation of halogen gases from sea salt aerosol. However, sodium is not the only cation present in atmospheric aerosols. Inland aerosols originating from wind-blown dust and cloud water droplets both contain mineral salts. In this dissertation we use classical molecular dynamics simulations to explore the effect of alkali and alkaline earth metal cations on chloride partitioning at the liquid/vapor interface. A correlation is observed between average induced dipole of a halide anion and its surface propensity. Additionally, we explore the effect of co-dissolved halide ions on the interfacial partitioning of nitrate. In sodium nitrate solution at finite concentrations, molecular dynamics simulations suggest that nitrate is depleted from the liquid/vapor interface. Previous studies by Wingen et al. have shown that sodium chloride can affect the partitioning of nitrate at the liquid/vapor interface. Chloride is present at the liquid/vapor interface. Sodium is attracted to the chloride, and nitrate is attracted to the sodium. In this way the addition of chloride is predicted to result in increased interfacial concentrations of nitrate relative to neat solution. In collaboration with X-ray photoelectron spectroscopy experiments and nitrate photolysis experiments we confirm that addition of bromide and iodide has a similar effect.

This dissertation focuses on fundamental studies to identify materials that detect and degrade common organic environmental pollutants Chapter 1 represents the overview of two widespread ground water contaminants: organohalides and organophosphorus compounds. Due to continuous usage of these compounds as well as their toxicity, reliable and sensitive methods for their detection and degradation are urgently needed. In Chapter 2 a description of molecular sensors designed with high sensitivity and selectivity to detect and distinguish between three organophosphorus (OP) pesticides are described. These sensors provide dual optical and electrochemical signals for detection, which minimizes false-positives. The signal transduction occurs in real time with detection limits in the ppm range Chapter 3 reports an organic molecule 9,11,20,22-tetraaza-tetrapyridopentacene (TATPP), capable of storing and shuttling multiple electrons, which are desirable for potential applications including remediation of environmental pollutants. We demonstrate the ability to photochemically modulate the reduction of TATPP and we investigate its reactivity. Chapter 4 describes the degradation of the chlorinated ethylenes: cis-1,2-dichloroethylene (cis-DCE), trichloroethylene (TCE) and tetrachloroethylene (PCE). Flavin mononucleotide (FMN) was used as a catalyst to aid in the degradation process. FMNH2 was produced in methanol solvent by the photoreduction of FMN. In aqueous solution, FMN was not fully reduced to FMNH2 but instead yielded the semiquinone radical FMNH&bull；. However, when FMN was anchored to nanocrystalline TiO2, band gap irradiation resulted in electron transfer from the TiO2 conduction band to FMN, thus yielding FMNH2. The FMNH2 generated in aqueous solution on the TiO2 surface was a stronger reductant toward chlorinated ethylenes, relative to FMNH2 in solution. By combining the reactivity of the TiO2 conduction band electrons (TiO2(e -CB)) with FMNH2, the reduction rate constants for the chlorinated ethylenes increased by two orders of magnitude relative to FMNH2 alone. In Chapter 5, we report that the FMN/TiO2 hybrid catalyst is effective toward the reduction of three organophosphorus compounds: fenthion, ethion and diethyl chlorophosphate. The reactivity of the catalyst with the organophosphorus compounds occurs at mild conditions in both aqueous solutions and in organic solvents.

Plant, invertebrate and feather delta13C and delta 15N stable isotopic signatures were used to trace avian plant production sources and prey items in five habitats of coastal Georgia: tidal forest, oak forest, pine forest, shrub and saltmarsh. Isosource 1.3.1 mixing models of plant production sources were successful on Sapelo Island where there were large differences in photosynthetic pathways and hydrology, but failed in the Clayhole Swamp. Model sensitivity analysis indicated that the trophic position was the most important parameter to know for partitioning plant production sources and isotopic enrichment of delta13C and delta15N in birds were equally important in determining prey items. Painted Buntings, the species of highest concern in the region, were almost as dependent on saltmarsh vegetation as they were on shrub and forest vegetation &sim；40%). Greater dependence of young of year Yellow-throated Warblers, White-eyed Vireos and Brown-headed Nuthatches on C3 saltmarsh vegetation suggests the saltmarsh may be providing an important source of protein for nestling birds across all habitats on Sapelo Island. Avian conservation efforts in coastal Georgia should include nearby saltmarsh to provide not only the necessary food resources for shrub-associated species, but also for forest interior species during the breeding season. Estimated habitat changes for 2100 due to climate change induced sea-level rise and coastal development indicate that sea-level rise is the greatest threat to saltmarsh and coastal shrub habitat, whereas accelerated urban development is the greatest threat to oak and pine forests. Tidal forests may serve as important refuges for closed-canopy species, such as Northern Parula, that will lose their preferred oak and pine habitats.

The Pearl River Delta is a typical developing region. It lies in the cloud-prone and rainy area of south China with multi-species of crops cultured in the agriculture areas. With a goal of developing an efficient, timely and accurate crop growth monitoring program in this area, field measurement, satellite SAR remote sensing technique, quantitative analysis of the crop biophysical parameters, and radar backscatter modeling methods have been integrated to study the multi-temporal and multi-polarized SAR data in estimating plant parameters LAI, fresh biomass) of rice and sugarcane crop, and mapping the agricultural land cover categories of the study area in the PRD. First, the field survey campaigns have been carried out from March 22, 2007 to December 27, 2007 around 5-15 days in the interval in the study area of Nansha Island. The field work includes the survey of spatial distribution of various land use and crop types and the ground measurements of the crop biophysical parameters such as the plant height, leave area index, fresh biomass, and plant water content) and the soil parameters such as the soil water content and surface roughness parameters) of rice field and sugarcane field. And at the same time, the ENVISAT ASAR data were acquired from March 22, 2007 to December 27, 2007 in the interval of 35 days. During the acquisition dates of the ENVISAT ASAR data, the field surveys were also conducted. Second, field surveys were combined with the ENVISAT ASAR data to map the agricultural area. The analysis of the temporal radar backscatter characteristics of various land cover categories demonstrated that the time series of C-band SAR data is efficient in separating the eight land cover categories rice paddy, sugarcane, banana, lotus ponds, mangrove wetlands, fish ponds, seawater, and buildings) in the PRD. The decision tree classifier is also approved to work efficiently on satellite SAR images with an overall accuracy of 77% and the Kappa coefficient of 0.74. The acreages of the land cover categories were also derived from the classification result with accuracies from 70% to 90%. Third, in the study of rice growth monitoring, the trends of the relationships between C-band radar backscattering coefficients and rice parameters plant height, LAI, fresh biomass, et al.) are proved to be constant with the reports in previous literatures. It was demonstrated that the differences between HH- and VV-polarized backscatter are not so evident around 0.5 dB) in rice paddy canopies during the crop growth cycle. Moreover, by inducting a semi-empirical soil surface scattering component, a modified Water Cloud Model was developed to simulate the radar backscatter in rice crop canopies in different ground background situations water surface, and soil surface) and to estimate the rice LAI and above ground fresh Biomass with reasonable accuracy. The rice growth conditions were displayed by LAI map and Biomass map generated from the model estimation, and the accuracies of the LAI and Biomass level classification are 0.77 and 0.71. Fourth, the sufficient ground measurements and simultaneous C-band HH- and VV-polarized SAR data of sugarcane crop have enriched the knowledge of understanding the temporal radar scatter mechanisms in sugarcane canopies. The C-band VV-polarized radar backscatters are larger than those of HH-polarization during the sugarcane growth cycle, and the difference is around 0.5 dB to 2 dB. The theoretical model MIMICS was adapted in modeling the scattering terms in sugarcane fields to interpret the temporal behavior of radar backscatters. For more robotic operation, the empirical regression models were used in estimation of the sugarcane LAI and fresh biomass, and mapping the sugarcane growth situation. The accuracies of the sugarcane LAI map and Biomass map are 0.74 and 0.70, respectively. In conclusion, the C-band ENVISAT ASAR data can be efficiently used in the Pearl River Delta to monitor the crop growth, including the crop spatial distribution, crop acreages, and crop growth situation evaluation. The efficient crop growth monitoring program can not only help instruct the flexible farming actions, but also estimate the crop yield production for the decision-making government. Abstract shortened by UMI.)

Polychlorinated biphenyls PCBs) are a class of persistent organic pollutants that are found in the environment since the 1970s due to its heavy usage in transformers and paints. PCBs are highly lipophilic and tend to bioaccumulate in tissues of animals. PCBs are also known to biomagnify through the food web. On the other hand, polybrominated diphenyl ethers PBDEs) are contaminants that only recently emerged in the last decade. PBDEs also have the ability to bioaccumulate and biomagnify, but studies have shown that PBDEs are more readily metabolized than PCBs. The most likely route of PBDE metabolism is through initial transformation by cytochrome P450s CYPs). Some of the main metabolic products are hydroxylated PBDEs that resemble thyroxin and other hormones in the body. Hence, these metabolites could potentially act as endocrine disruptors. Therefore, there is heightened concern when these compounds accumulate in the body. In order to understand the mechanism of transport, accumulation, and metabolism of these halogenated compounds in the environment and in biota, it is important to be able to analyze them in different matrices and measure both the parent compounds and metabolic products at low concentrations. For these reasons, methods were developed for the analysis of these compounds in environmental and biological samples. Specifically, extraction and gas chromatographic/mass spectrometric GC/MS) methods were developed to analyze PCBs and PBDEs in common carp muscle, plasma and liver. Extractions were either completed by liquid-liquid extraction LLE) for liquid samples or pressurized liquid extraction PLE) for solid samples. Two GC/MS instruments were used and evaluated, one with single quadrupole MS and the other with a triple quadrupole MS, both with electron impact ionization. To determine the extent of metabolism of PBDEs in humans, incubations of BDEs 47, 99 or 153 were prepared with human liver microsomes. A method was also developed to analyze for 14C-labeled BDEs 47, 99, 153 and their metabolites after incubation with human liver microsomes which contain CYPs. Analysis of radiolabeled PBDE and metabolites was achieved using a high performance liquid chromatograph with an on-line radiochemical detector. Non-labeled compounds and metabolites were also analyzed by GC/MS. In addition, a method for the analysis of hydroxylated-PBDEs OH-PBDEs) by liquid chromatography/with ion-trap mass spectrometry LC/MS) was developed to facilitate the identification of novel metabolites in biological samples. The LC/MS method was developed using atmospheric pressure chemical ionization APCI) to allow for negative ionization of OH-PBDEs. The fragmentation pattern obtained from tandem MS analysis by ion-trap MS provided valuable structural information to allow identification of metabolites. Common carp analyzed from Eastern Lake Erie have high levels of PCBs and detectable levels of PBDEs. PCB concentrations ranged from non-detect to 12,000 ng/g lipid in muscle where PCBs 138 and 153 were the most detected. PBDE concentrations in muscle ranged from 1.5 to 100ng/g lipid, where PBDE 47 was the most detected compound. Incubations of BDE 47, 99 and 153 with human liver microsomes showed hydroxylation and cleavage of BDEs 47 and 99. BDE 153 had no detectable metabolites. BDEs 47 and 99 were dihydroxylated or cleaved into bromophenols. BDE 99 was metabolized at a faster rate than BDE 47 indicating that metabolism of 99 is one possible reason for the increased abundance of BDE 47 in tissues. Results indicated that LC/MS with APCI ionization is suitable for the detection of low levels of OH-PBDEs, which allowed for the separation of nine OH-PBDEs ranging from tribrominated to hexabrominated. LC/MS is more advantageous than GC/MS in the analysis of polar metabolites because there is no need to derivatize the hydroxylated metabolites prior to analysis.

All sea turtle populations face the risk of extinction. Of the threats to sea turtles, the effects of environmental chemicals are the least understood. Polychlorinated biphenyls PCBs) are toxic, persistent, ubiquitous, anthropogenic halogenated organic contaminants HOCs). While anthropogenic HOCs are notorious for their toxicity, exposure to naturally produced HOCs, many of which exist in the marine environment, may also cause adverse effects. The purpose of this dissertation was to gain insight into possible impacts of HOCs on the health of sea turtle populations by assessing biotransformation enzymes, as well as the accumulation and metabolism of HOCs in several species of sea turtles- loggerhead Caretta caretta), green Chelonia mydas), olive ridley Lepidochelys olivacea), and hawksbill Eretmochelys imbricata). The results showed that sea turtle livers possess the biotransformation enzymes cytochrome P450 CYP) and glutathione S-transferase GST). Western blots revealed CYP2- and CYP3-like proteins, but do not CYP1A-like proteins. Spectrophotometric assays indicated that sea turtles showed similar GST kinetic parameters, but inter- and intra-species variation in activities towards GST class-specific substrates. PCBs accumulated in the livers of sea turtles, with levels ranging from 5–25 ng/g, as measured by gas chromatography with electron capture detection. In vitro incubations of sea turtle liver microsomes with 2,2,5,5-tetrachlorinated biphenyl PCB 52) indicated the formation a hydroxylated metabolite by liquid chromatography/mass spectroscopy, while incubations with 3,34,4-tetrachlorinated biphenyl PCB 77) did not reveal metabolites. Taken together, these results supported a model in which rates of hepatic biotransformation may determine elimination and relative concentrations of PCBs in reptilian tissues. Hawksbill sea turtles feed primarily on marine sponges, which produce natural HOCs, such as 4,5-dibromopyrrole-2-carboxylic acid DBPC), as deterrents against predation. The lack of detectable in vitro metabolism of DBPC by hawksbill sea turtles, as measured by liquid chromatography with radioactivity detection, indicated that biotransformation may not be the primary mechanism of tolerance to natural dietary. Kinetic analysis of spectrophotmetric assays indicated non-substrate binding of DBPC by GST, which suggested potential protection from sponge HOCs via GST transport or sequestration. The information in this dissertation provides critical knowledge to connect toxic effects of HOCs to sea turtle population decline.

Biodiesel is a renewable fuel alternative being developed, as its similarities to petroleum diesel allow for distribution by available infrastructure and direct use in diesel engines. Biodiesel is comprised of monoalkyl esters of long chain fatty acids derived from vegetable oils and animal fats. The majority of commercial operations utilize transesterification catalysis to result in the fuel alternative and glycerol by-product. Though the final product is environmentally benign, current production is not ecologically sound on large-scales due to necessary washing of the caustic mixture and separation of by-products. The objective of this research was to develop a recyclable heterogeneous catalyst for biodiesel synthesis capable of reacting recycled oils and waste grease feedstock and whose optimal catalytic conditions are environmentally benign on an industrial scale. Synthesis of a titanium niobate multiphase crystal was optimized for application in biodiesel processing. Optimal catalyst synthesis ratio for biodiesel application was 1:2:1, TiO2:K2CO3:Ni 2O5. In the synthesis procedure, impregnation of K2 CO3 serves as a promoter for titanium support on which niobium oxide is deposited. Catalyst is calcined at 500&deg；C for three hours to achieve optimal crystal form. Catalyst character was studied by XRD and BET analysis, confirming under synthesis conditions a robust, amorphous crystal results. Multiphase crystal form is maintained through multiple recyclings of catalyst. Optimal calcining conditions reduce operation energy input and result in an effective catalyst for biodiesel application. Biodiesel processing variables were optimized for the titanium niobate multiphase crystal catalyst including, catalyst activation/reactivation conditions, reactant ratios, reaction temperature, and internal stir rate. Transesterification of soybean oil with methanol achieved 99% conversion in 5 minutes. Reaction was in an open system under reflux with an internal temperature of 67&deg；C and stir rate at 300 rpm. Molar ratio of methanol:oil was 3:1 using 7.4 wt.% catalyst. Restaurant grease resulted in equal conversion in one hour under pressure of 2.72 atm and temperature of 105&deg；C. In an open system, the waste grease required 15 hours to reach similar conversion. Recycling the catalyst with potassium salt regenerated surface active sites and maintained catalyst efficiency up to 21 times, with no decrease expected in continued use. Quantitative analysis of transesterification was by 1H NMR. Optimized time of reaction and reaction conditions are a significant improvement over current industrial processing systems and practical for large-scale implementation. The quality of biodiesel is determined by the level of free and bonded glycerol by-product. Elevated glycerol concentration leads to injector fouling and excessive carbon deposits. To date, the standardized analytical method utilizes GC, however cost and availability to manufacturers limits this technique for strict quality control. A bench-top method was developed to extract glycerol by-product by normal-phase SPE column. In the optimized method, glycerol is concentrated and reacted with anthrone reagent for quantitative analysis by developed spectrophotometric method against a standard curve. The method developed has a detection range comparable to that of the established ASTM D6584 GC technique and published HPLC method. With limited instrumentation and instruction necessary, the method would be favorable for adoption by biodiesel manufacturers.

This two-part thesis describes the analysis of environmental pollutants at depth without bringing sample to the surface. In the first part a new high temperature transfer line, membrane inlet probe HTTL-MIP) coupled to a photoionization detector PID) and gas chromatograph/mass spectrometer GC/MS) was used to rapidly profile and speciate polycyclic aromatic hydrocarbons PAH) in the subsurface. PID signals were in agreement with GC/MS results. Correlation coefficients of 0.92 and 0.99 were obtained for discrete and composite samples collected from the same exact location. Continuous probe advancement with PID detection found coal tar, a dense nonaqueous liquid, in soil channels and saturated media. When samples were collected conventionally, split, solvent extracted and analyzed in the field and confirmation lab, GC/MS measurement precision and accuracy were indistinguishable； despite the fact the field lab produced data five times faster than the lab using standard EPA methods. No false positive/negatives were found. Based on these findings, increased confidence in site conceptual models should be obtained, since PID response indicated total PAH presence/absence in “real-time,” while GC/MS provided information as to which PAH was present and at what concentration. Incorporation of this tool into a dynamic workplan will provide more data at less cost enabling environmental scientists, engineers, and regulators to better understand coal tar migration and its impact on human health and the environment. The second part of this thesis is based on an improved 3-stage Peltier freeze trap, which efficiently pre-concentrates volatile coal tar and petroleum hydrocarbons, and an integrated system for detecting pollutants on-line, in real time by photoionization detection and quantitation by gas chromatography/mass spectrometry GC/MS) as the probe is advanced into the subsurface. Findings indicate measurement precision and accuracy for volatiles meet EPA criteria for hazardous waste site investigations. When a Teflon membrane inlet is used to detect contaminants in groundwater, its 140 &ordm；C temperature limit restricts analyte collection in soil to C2-phenanthrenes. Two case studies demonstrate the probe is well-suited to tracking petroleum and coal tar plumes from source to groundwater. Key words: in situ sampling probe, subsurface, dense non aqueous phase liquids, hazardous waste site characterization, photoionization detector, GC/MS

Traditional methods of pesticide detection used on Prince Edward Island (PEI) are very expensive and time consuming. These methods are typically only useful after harm has been done to the environment, and cannot be used in prevention. A new method for rapid, on-site detection of these pesticides would not only be of value financially, it could also prove to be essential in preventative measures, for example by monitoring streams. Fluorescence, the light emitted by electronically excited molecules, is a highly sensitive technique for detecting and measuring the concentration of molecules in solution. Most pesticides used on Prince Edward Island show only weak native fluorescence in water. However by forming a supramolecular host:guest inclusion complex, in which the pesticide “guest” becomes included within the internal cavity of an organic host molecule, this fluorescence is increased for many guest molecules. In some cases, this enhancement of the fluorescence might be sufficiently large enough to allow for the development of a fluorescence-based trace analysis technique with sensitivity in the required ppb level. In this project, native and modified cyclodextrins and their effect on the fluorescence of a series of pesticides used on PEI, specifically carbofuran, carbaryl and chlorothalonil along with five others, is measured with results varying from 670 parts per trillion for carbaryl to 69 ppb for Chlorothalonil. In addition, UV photolysis of certain pesticides can also lead to enhanced fluorescence such as azoxystrobin and imidacloprid, and thus also be a technique used in the trace detection of pesticides. This occurs via creation of a more highly fluorescent molecule from a previously non- fluorescent or weakly fluorescent pesticide. Synchronous scanning, a method of measuring fluorescence by scanning both excitation and emission wavelengths simultaneously, which results in narrower measured emission bands is also examined in detail to separate fluorescent bands of similar emission wavelengths, and thus simultaneously measure a set of two or more pesticides in solution. Overall, the main goal of this work is to develop a sensitive, enhanced fluorescence based trace analysis technique for pesticides, which could eventually be carried out using a portable fluorimeter, so that samples could be analyzed on site, in a matter of minutes, rather than in a lab over a period of days.