Characterizing the toxicity of oil sands process-affected water

Oil sands process-affected water (OSPW) is produced during extraction of bitumen in the surface-mining oil sands industry in Alberta, Canada. Due to observed acute and chronic toxicity of the dissolved organic fraction of OSPW, it is currently stored in tailings ponds to be remediated and eventually returned to the surrounding environment. To this end, endpit lakes are a proposed passive remediation strategy for OSPW related toxicity, of which BaseMine Lake (BML) is the first full scale commercial test. The purpose of this thesis was to identify and characterize toxic chemical classes in the dissolved organic fraction of OSPW collected from BML to aide the development of water quality objectives and release guidelines for the oil sands industry. Using a bioassay-effect directed analysis approach and ultrahigh resolution mass spectrometry, the dissolved organic fraction of OSPW was iteratively fractionated and biologically tested to identify acutely toxic chemical classes. This work was further built upon by the development of a predictive acute aquatic toxicity model for embryos of fathead minnow (Pimephales promelas) exposed to OSPW related chemicals to support the development of release guidelines in the oil sands. To investigate potential mechanisms of acute toxicity of dissolved organic chemicals in OSPW, an Escherichia coli whole genome reporter system was used and provided evidence to support narcosis as the critical mechanism of OSPW related acute toxicity. Furthermore, the fathead minnow short term 21-day reproductive bioassay was used to investigate the potential for OSPW related chemicals to disrupt reproduction. Results of this thesis support earlier works and confirmed a role for naphthenic acids in the acute toxicity of OSPW. However, novel acutely toxic chemical classes containing oxygen, sulphur or nitrogen were also identified. An acute aquatic toxicity model was developed which is sufficiently robust to predict toxicity of dissolved organic chemicals in OSPW within biological variation associated with toxicity tests and provides an alternative to in vivo test methods typically applied to complex environmental mixtures. In addition, hepatosomatic index was identified as an indicator of chronic exposure of male fathead minnow to OSPW. Overall, this work provides important toxicity and chemical information that will aide in the development of reclamation and monitoring programs in the oil sands region of Alberta, Canada

Effect of vision therapy on measures of oculomotor function of patients presenting with post-concussion syndrome

Oculomotor dysfunction is a common symptom of post-concussion syndrome (PCS). By use of a retrospective analysis approach, the efficacy of Vision Therapy (VT) for the treatment of PCS related symptoms of the visual system was investigated. Overall, 56 patients were selected for inclusion in this study, all of which presented with clinical impairment of at least one measure of oculomotor functioning. Activities related to VT were wide-ranging and case-dependent, but all aimed to improve one of the five main areas of visual function. Following completion of VT, all patients demonstrated statistically or clinically significant improvements, as defined by use of Morgan’s Norms, in at least one measure of oculomotor functioning related to PCS. In general, improvements in measures of oculomotor functioning were greatest for near point of convergence, vergence facility and accommodative facility. Patients receiving 20 sessions of VT had improved and less variable outcomes when compared to those receiving 5-10 sessions of VT. In addition, VT was found to improve symptoms of visual discomfort in patients presenting with PCS. Results of this retrospective analysis demonstrate significant improvements in measured outcomes for all patients receiving VT and support VT as a treatment option for symptoms of PCS

Effet de la thérapie visuelle sur les mesures de la fonction oculomotrice chez les patients atteints du syndrome de post-commotion

La dysfonction oculomotrice est un symptôme courant du syndrome de post-commotion (SPC). Dans cette étude, on a étudié rétrospectivement l’efficacité de la thérapie visuelle (TV) pour le traitement des symptômes liés au SPC par rapport au système visuel. Dans l’ensemble, 56 patients ont été sélectionnés, qui présentaient tous une déficience sur le plan clinique d’au moins une mesure du fonctionnement oculomoteur. Les activités liées à la TV étaient grandement variées et établies au cas par cas, mais elles visaient toutes à améliorer l’une des cinq principales fonctions visuelles. À la suite de la TV, tous les patients ont démontré des améliorations statistiquement ou cliniquement significatives, comme définies par l’utilisation des normes de Morgan, dans au moins une mesure du fonctionnement oculomoteur lié au SPC. En général, les améliorations les plus importantes des mesures du fonctionnement oculomoteur concernaient le point de convergence proche, la flexibilité de vergence et la flexibilité d’accommodation. Les patients qui ont suivi 20 séances de TV avaient de meilleurs résultats (aussi moins variables) que ceux qui ont suivi entre 5 et 10 séances. De plus, la TV a diminué les symptômes d’inconfort visuel chez les patients qui présentaient un SPC. Les résultats de cette analyse rétrospective démontrent des améliorations importantes dans les résultats mesurés pour tous les patients qui ont suivi une TV et appuient la TV comme option de traitement pour les symptômes du SPC

Effect of Lipid Partitioning on Predictions of Acute Toxicity of Oil Sands Process Affected Water to Embryos of Fathead Minnow (<i>Pimephales promelas</i>)

Dissolved organic compounds in oil sands process affected water (OSPW) are known to be responsible for most of its toxicity to aquatic organisms, but the complexity of this mixture prevents use of traditional bottom-up approaches for predicting toxicities of mixtures. Therefore, a top-down approach to predict toxicity of the dissolved organic fraction of OSPW was developed and tested. Accurate masses (i.e., <i>m</i>/<i>z</i>) determined by ultrahigh resolution mass spectrometry in negative and positive ionization modes were used to assign empirical chemical formulas to each chemical species in the mixture. For each chemical species, a predictive measure of lipid accumulation was estimated by stir-bar sorptive extraction (SBSE) to poly­(dimethyl)­siloxane, or by partitioning to solid-supported lipid membranes (SSLM). A narcosis mode of action was assumed and the target-lipid model was used to estimate potencies of mixtures by assuming strict additivity. A model developed using a combination of the SBSE and SSLM lipid partitioning estimates, whereby the accumulation of chemicals to neutral and polar lipids was explicitly considered, was best for predicting empirical values of LC50 in 96-h acute toxicity tests with embryos of fathead minnow (<i>Pimephales promelas</i>). Model predictions were within 4-fold of observed toxicity for 75% of OSPW samples, and within 8.5-fold for all samples tested, which is comparable to the range of interlaboratory variability for in vivo toxicity testing

Effects-Directed Analysis of Dissolved Organic Compounds in Oil Sands Process-Affected Water

Acute toxicity of oil sands process-affected water (OSPW) is caused by its complex mixture of bitumen-derived organics, but the specific chemical classes that are most toxic have not been demonstrated. Here, effects-directed analysis was used to determine the most acutely toxic chemical classes in OSPW collected from the world’s first oil sands end-pit lake. Three sequential rounds of fractionation, chemical analysis (ultrahigh resolution mass spectrometry), and acute toxicity testing (96 h fathead minnow embryo lethality and 15 min Microtox bioassay) were conducted. Following primary fractionation, toxicity was primarily attributable to the neutral extractable fraction (F1-NE), containing 27% of original organics mass. In secondary fractionation, F1-NE was subfractionated by alkaline water washing, and toxicity was primarily isolated to the ionizable fraction (F2-NE2), containing 18.5% of the original organic mass. In the final round, chromatographic subfractionation of F2-NE2 resulted in two toxic fractions, with the most potent (F3-NE2a, 11% of original organic mass) containing predominantly naphthenic acids (O₂^–). The less-toxic fraction (F3-NE2b, 8% of original organic mass) contained predominantly nonacid species (O⁺, O₂⁺, SO⁺, NO⁺). Evidence supports naphthenic acids as among the most acutely toxic chemical classes in OSPW, but nonacidic species also contribute to acute toxicity of OSPW