The Great Lakes has been impaired by elevated concentrations of contaminants, and different regulatory actions are taken to decrease theses concentrations. Recent research of Dr. Azim suggests a decline in mercury levels in the Lake Erie, and an increase in the Hg concentration in the fish communities. This research is a follow up study to examine whether the contaminant levels are indeed increasing. In the first chapter we evaluate the temporal trends of polychlorinated biphenyls (PCBs) in Lake Erie fish over the last 30 years by conducting the Exponential and Dynamic Linear Modeling analysis. DLM analysis in the chapter two detects the PCB and Hg contaminant trends in a broader range. There is a high variability in two contaminants trends. These patterns may be because of factors such as fish physiological parameters, and the impact of invasive species. The results of my research will contribute to the Toxics Reduction Strategy.

The Great Lakes has been impaired by elevated concentrations of contaminants, and different regulatory actions are taken to decrease theses concentrations. Recent research of Dr. Azim suggests a decline in mercury levels in the Lake Erie, and an increase in the Hg concentration in the fish communities. This research is a follow up study to examine whether the contaminant levels are indeed increasing. In the first chapter we evaluate the temporal trends of polychlorinated biphenyls (PCBs) in Lake Erie fish over the last 30 years by conducting the Exponential and Dynamic Linear Modeling analysis. DLM analysis in the chapter two detects the PCB and Hg contaminant trends in a broader range. There is a high variability in two contaminants trends. These patterns may be because of factors such as fish physiological parameters, and the impact of invasive species. The results of my research will contribute to the Toxics Reduction Strategy.

Ingestion exposure estimates typically use a default bioavailability of 100%, thereby assuming that the entirety of an ingested dose is absorbed into systemic circulation. However, the actual bioavailability of ingested contaminants is oftentimes lower than 100%. The research described herein investigates the use of the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) for the calculation of <i>in vitro</i> bioaccessibility (IVBA), a conservative predictor of bioavailability, of mercury (Hg) from traditional northern foods and arsenic (As) from soils. The primary objective of the research described herein is to address data-gaps which have hindered attempts to incorporate IVBA into risk assessment on more than a case-by-case basis. The hypotheses of this thesis are that (1) the bioaccessibility of contaminants is dependent upon concentration due to kinetic limitations on dissolution, (2) gastrointestinal (GI) microbes in the ileum and colon alter contaminant bioaccessibility and/or speciation, (3) the GI microbial effect on bioaccessibility is toxicologically relevant, and (4) metal bioaccessibility is predictable according to dissolution kinetics.<p> Mercury bioaccessibility from country food samples was independent of total Hg concentration (F=0.5726, P=0.578) whereas As bioaccessibility was inversely related to total As concentration for Nova Scotia mine tailings, synthesized ferrihydrite with adsorbed AsV, and synthesized amorphous scorodite (P=2 x 10-10). Isotherm analysis indicated that, at high soil As concentrations, saturation of simulated GI fluids limited As bioaccessibility under gastric conditions whereas kinetic limitations constrained As bioaccessibility under intestinal conditions. Additionally, we demonstrated that GI microbes may affect Hg bioaccessibility, either increasing or decreasing bioaccessibility depending upon the type of food. For example, the bioaccessibility of HgT decreased in the presence of GI microbial activity for caribou kidney, caribou tongue, seal blood, seal brain, seal liver, and walrus flesh. In contrast, HgT bioaccessibility from Arctic char and seal intestine increased in the presence of GI microbial activity. Similarly, colon microbial activity increased (Fishers Protected LSD, P<0.05) As bioaccessibility from synthesized amorphous scorodite (56 110%), Nova Scotia mine tailings (140 300%), an agricultural soil (53%) and an ironstone soil (350%) containing elevated arsenic concentrations. However, under small intestinal conditions, this microbial effect was transient and demonstrated a small effect size. The toxicological relevance of microbial effects upon As bioaccessibility was assessed using a juvenile swine model with co-administration of oral antibiotics (neomycin and metronidazole). This study research indicated that microbial effects on As bioaccessibility are not reflected in the juvenile swine model. For example, the microbial communities present in the pigs proximal colon clustered according to antibiotic treatment (e.g. microbial communities of antibiotic treated pigs differed from non-treated pigs). Despite this, the urinary arsenic excretion (and hence arsenic bioavailability) of antibiotic-treated juvenile swine orally exposed to soil-borne arsenic was equivalent (Holm-Sidak, P=0.930) to the urinary arsenic excretion of juvenile swine not treated with antibiotics. Therefore, in vitro GI models may not need to include a microbially active intestinal stage when measuring As IVBA.<p> Metal bioaccessibility from soils appears predictable according to fundamental chemical properties of the metal-of-concern. Specifically, metal bioaccessibility of 7 of the 13 metals (V, Ni, Zn, Cu, U, Cd, & Ba but not Tl, Pb, As, Se, Cr, and Hg) regulated according to Canadian Council of Ministers of the Environment Soil Quality Guidelines (CCME SQG) were strongly dependent (R2 = 0.7) on water exchange rate constants of metal cations (kH20) indicating that desorption kinetics may serve as the foundation of a predictive model of metal bioaccessibility.

Contamination of drinking water with metals is a major problem facing many areas of United States and the World. There is a need for an inexpensive remediation technology for the removal of metals in drinking water that can be applied to small rural water systems. This research will focus on the development of a process for removal of select metals from drinking water by limestone-based material. Metals in drinking water considered for this research include lead and selenium. Limestone-based material has demonstrated the potential to reduce select metals (lead, cadmium and arsenic) in drinking water, with the additional benefit of low-cost disposal of a stable waste product in ordinary landfills. Earlier research by the principal investigators using limestone-based material for drinking water treatment has clearly shown that this material can achieve metals removal of greater than 90 percent. This project will investigate techniques to improve removal efficiency of limestone-based material through adsorption and precipitation. This research will assist in the development of a granular adsorbent product that will remove metals and that can be manufactured and sold for use at the drinking water source, at point-of-use, or at point-of entry.

Pollen contamination is a severe problem in production breeding programs since it reduces the expected gain. In an attempt to solve this problem Skogforsk created an isolation experiment in the advanced Scots pine (Pinus sylvestris) seed orchard Västerhus in Västerbotten, Sweden. This experiment involves covering blocks of trees with a tent during the pollination period so that they only can mate with each other inside. To evaluate the effects of this tent treatment one tree from inside a tent with supplementary mass pollination (SMP) and one tree from the open control were chosen for this study. 48 seeds from each tree were sampled and genotypes at 9 microsatellite (SSR) loci. The likelihood and exclusion methods for paternity assignment were used to establish the fathers to these seeds. The results showed 0% contamination inside the tent and 4-8% outside in the control. The number of fathers contributed to the fertilization of the 48 seeds was 9 inside and 15 outside. The selfing rate was unexpectedly high, 10% inside the tent and 19% outside. The mating system inside the tent need to be further evaluated to fully understand what other effect the treatment has on the future progeny.

Current Canadian policies do not adequately prevent water contamination or mitigate the effects of existing polychlorinated biphenyl pollution. There is conflict between the Canadian government and the Inuit people over how to approach the pollution problem, arising from a clash of cultural values and traditions. Legislation related to healthcare is an inherently sensitive issue and some measures that seem acceptable to westernized societies are not appropriate for the Inuit. The purpose of this thesis is to answer (a) why polychlorinated biphenyls (PCBs) are in the Arctic, (b) what the effects of PCBs are on the Arctic people, and (c) how healthcare policy can address the issue.

Les Atikamekw sont un peuple autochtone du Québec réparti dans les communautés de Manawan, Wemotaci et Opitciwan. Ils consomment de la nourriture traditionnelle (gibier, poisson et sauvagine) qui contient potentiellement des contaminants environnementaux, dont des métaux lourds et des polluants organiques persistants. Or, la consommation de nourriture traditionnelle comporte maints avantages nutritionnels, socio-culturels, spirituels et économiques. Des inquiétudes ont été soulevées par les Atikamekw quant à la présence de contaminants dans leur nourriture et leur organisme. Une étude épidémiologique transversale participative a été menée auprès de 189 Atikamekw, dont 63 enfants. Les objectifs principaux sont de dresser le profil d'exposition aux contaminants et lorsque les expositions sont confirmées, de trouver des pistes de solutions visant la conciliation des bénéfices et des risques de la consommation de nourriture traditionnelle. Concrètement, cette étude vise à valider l'utilisation des questionnaires de fréquences alimentaires et 24h-rappel dans le but de dégager un profil d'exposition au méthylmercure (MeHg) selon la fréquence de consommation de nourriture traditionnelle. Pour ce faire, des questionnaires de fréquences alimentaires, 24h-rappel et socio-démographiques ont été administrés et les niveaux de MeHg ont été déterminés par des analyses sanguines et capillaires, par spectrométrie d'absorption atomique à vapeur froide. Les grands consommateurs de nourriture traditionnelle avaient des apports supérieurs en protéines, fer, zinc, cuivre, niacine et vitamine B12 et moindres en lipides, sucres totaux, acides gras monoinsaturés et saturés que les petits consommateurs de nourriture traditionnelle, mais avaient des niveaux de MeHg plus élevés (p<0,05). L'utilisation des questionnaires alimentaires permet de dégager d'une part le profil nutritionnel et d'autre part l'exposition au mercure, ce qui permet à la nutritionniste de transmettre l'information nutritionnelle adaptée aux différents groupes de consommateurs de nourriture traditionnelle tout en évitant la surexposition au mercure. Selon le profil de ces grands consommateurs (âge et genre), des interventions pourront être effectuées par exemple autour de la diversification des espèces et de la grosseur des poissons consommés et des lieux de pêche, ou tout autre mesure jugées pertinentes par la communauté. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Atikamekw, Bénéfices, Risques, Nourriture traditionnelle, 24h-rappel, FFQ, Méthylmercure, Profil d'exposition.

The behaviour of hydrocarbon fuels in contaminated groundwater systems is studied using a multicomponent reactive transport model. The simulated processes include residual NAPL dissolution, aerobic and anaerobic biodegradation with daughter-product transport, and transport of a reactive carrier with mixed equilibrium/kinetic sorption. The solution algorithm is based on a three-dimensional Galerkin finite element scheme with deformable brick elements and capacity for a free watertable search. Nonlinearities are handled through Picard iteration. Convergence is rapid for most applications and mass balance errors for all phases are minimal. The model is first applied to simulate a pilot scale diesel fuel dissolution experiment in which humic acid is used as a natural organic carrier to enhance dissolution and to promote biodegradation of the aqueous components. The pilot scale experiment is described by Lesage et al. (1995) and Van Stempvoort et al. (2000). The conceptual model includes 8 unique components dissolving from 500 mL of residual diesel fuel within a 3D saturated domain. Oxygen-limiting competitive aerobic biodegradation with a dynamic microbial population is also included. A mixed 2-site equilibrium/kinetic model for describing sorption of the carrier to the aquifer solids was adopted to reproduce the observed breakthrough of the humic acid and organic components. Most model parameters were obtained independently with minimal calibration. Batch sorption data were found to fit well at the pilot scale, however biodegradation and dissolution rates were not well known and had to be fitted. Simulations confirmed the observed 10-fold increase in effective solubility of trimethylnaphthalene, and increases on the order of 2-5 for methyl- and dimethylnaphthalene. The simulated plumes showed almost complete attenuation after 5 years, in excellent agreement with observed data. A sensitivity analysis showed the importance of carrier concentrations, binding coefficients, dissolution and biodegradation rates. Compared to a dissolution scenario assuming no carrier, the humic acid-enhanced dissolution case decreased the remediation time by a factor of about 5. The second application of the model involves simulating the effect of ethanol on the persistence of benzene in gasoline-impacted groundwater systems. The conceptual model includes a 4-component residual gasoline source which is dissolving at the watertable into a 3D aquifer. Comparisons are made between dissolved plumes from a gasoline spill and those from an otherwise equivalent gasohol spill. Simulations have shown that under some conditions, a 10% ethanol component in gasoline can extend the travel distance of a benzene plume by at least 150% relative to that from an equivalent ethanol-free gasoline spill. The increase is due to preferred consumption of oxygen by ethanol and a corresponding reduction in the biodegradation rate of benzene while the two plumes overlap. Because of differences in retardation however, the ethanol and benzene plumes gradually separate. The impact therefore becomes limited because oxygen rapidly disperses behind the ethanol plume and benzene degradation eventually resumes. A sensitivity analysis for two common spill scenarios showed that background oxygen concentrations, and benzene retardation had the most significant influence on benzene persistence. A continuous gasohol spill over 10 years was found to increase the benzene travel distance by over 120% and a pure ethanol spill into an existing gasoline plume increased benzene travel distance by 150% after 40 years. The results are highly relevant in light of the forthcoming ban of MTBE in California and its likely replacement by ethanol by the end of 2002.

Ethanol can affect the biodegradation of gasoline hydrocarbons in groundwater. High concentrations of ethanol can be toxic to subsurface microorganisms that are otherwise capable of degrading hydrocarbons, such as benzene, toluene, ethylbenzene and xylenes (BTEX). At lower concentrations, ethanol may hinder BTEX degradation through substrate competition and the depletion of inorganic nutrients (e.g., nitrogen and phosphorus), oxygen and other electron acceptors needed for BTEX degradation. A series of laboratory experiments were designed to study the effect of ethanol on aquifer microorganisms and on aerobic BTEX biodegradation. A microcosm experiment was conducted to investigate the effect of ethanol on the biodegradation of BTEX. Microcosms were set up with Borden aquifer material and groundwater in which oxygen and nutrients were not limited. These microcosms contained BTEX in combination with a range of ethanol concentrations. Under these favourable conditions, the presence of ethanol up to concentrations of 1.9% (v/v) (equivalent to 15000 mg/L) caused little inhibition of BTEX degradation. Further experiments were conducted to study the antimicrobial effects of higher concentrations of ethanol. Following exposure to ethanol concentrations of 25% (v/v) or higher, microbial activity and survival was significantly diminished. Results suggest that a high concentration ethanol slug will have a major impact on the microbial community but that there would likely be potential for recovery. The recovery potential was examined further in laboratory column experiments designed to simulate a dynamic field situation where a high ethanol pulse is followed by a BTEX plume. These column experiments were conducted with Borden aquifer material and groundwater under aerobic conditions. The concentration of the ethanol pulse was 25% (v/v), which was expected to significantly alter the microbial population without destroying it. Following the ethanol exposure, groundwater and BTEX were allowed to flow through one column to simulate the reinoculation of microorganisms from upgradient groundwater advecting into the contaminated zone. The other column was fed with sterile groundwater and BTEX to evaluate the regeneration of within-column microorganisms that survived the ethanol exposure. Recovery in both columns was rapid. Unfortunately, during the recovery phase, sterility of the influent groundwater could not be maintained. As a result, recovery by regeneration could not be evaluated. Nonetheless, it is evident that recovery in terms of aerobic BTEX biodegradation was significant under the conditions of the column experiment. Ethanol did not appear to pose a long-term impact on BTEX biodegradation when oxygen and nutrients were in excess. In field situations, nutrients and electron acceptors may be limited; however, ethanol toxicity is not likely to cause a prolonged inhibition of BTEX biodegradation.

Brownfields have an important impact on health. They can influence physical health by increasing risk for health hazards such as the potential for injury hazards, disease transmission, or exposure to chemicals. They can also influence social health determinants like neighborhood level social capital or behavioral risk factors. Reusing brownfields for community gardens reduces environmental hazards and associated health hazards. It further promotes public health, and sustainable quality environment. Community gardens increase nutrition access, especially for many in low income populations, and community aesthetic. They also strengthen social cohesion and create recreational or therapeutic opportunities for a community, becoming part of the urban green space network. Special care must be taken to protect public health when reusing a brownfield for a community garden, like sampling for chemicals, cleaning up soil, and using protective garden designs. The overall benefit to the community is worth the initial investment required.