Identification of Oil Sands Naphthenic Acid Structures and Their Associated Toxicity to Pimephales promelas and Oryzias latipes

The oil sands, located in north-eastern Alberta, are one of the largest deposits of oil worldwide. Because the Alberta Environmental Protection and Enhancement Act prohibits the release of oil sands process-affected material into the environment, industry is storing vast quantities of tailings on mine lease sites. The oil sands industry is currently accumulating tailings waste at a rate of >105 m3/day, for which reclamation strategies are being investigated. Naphthenic acids (NAs) have been identified as the most toxic component of oil sands tailings as they are considered acutely toxic to a variety of biota, and are therefore a target contaminant for tailings pond reclamation strategies. Current literature based on Microtox® assays (marine bacteria Vibrio fischeri) suggests that lower molecular weight NAs are more toxic than higher molecular weight NAs. The following thesis involves the utilization of NA fractions and their relative toxicities to determine if NA toxicity is related to NA molecular weight. A previous study generated an oil sands-derived naphthenic acid extract (NAE), which was fractionated by distillation at stepped temperatures, yielding five fractions with increasing median molecular weights (Daltons). In the present study, the same extract and five fractions were utilized. To expand on the earlier characterization which involved a low resolution electrospray ionization mass spectrometry (ESI-MS), the whole extract and five fractions were analysed using electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and synchronous fluorescence spectroscopy (SFS). Mean molecular weights were generated for each fraction, and an increase in molecular weight with increasing fraction number was confirmed. Respective mean Daltons and relative proportions for each fraction are as follows: 237 and 11.9 % (fraction 1), 240 and 32.3% (fraction 2), 257 and 33.4% (fraction 3), 308 and 16.8% (fraction 4), and 355 and 5.6% (fraction 5). When chemical analyses of fractions were compared, it was determined that structures contributing to increased molecular weight included increased cyclic structures (up to 7-ring structures), aromaticity (mono- and diaromatics), nitrogen, sulfur, and oxygen heteroatoms, and dihydroxy/dicarboxy compounds. In addition, characterization data suggested the presence of NAs exhibiting estrogenic structures. Following chemical characterization, NA fractions were subject to embryo/larval bioassays using two fish species: Oryzias latipes (Japanese medaka) and Pimephales promelas (fathead minnow). Endpoints evaluated were mortality, time to hatch, hatch length, and abnormalities. Results suggest that relative NA fraction toxicity is not related to molecular weight, as no trend relating mean Dalton weight to toxicity was observed for any endpoint in both species. Acute toxicity data indicated differences between fractions as high as 2-fold, although results were species-dependent. Fraction 1 displayed the lowest potency (highest LC50) for both Japanese medaka (0.291 mM) and fathead minnow (0.159 mM). Fractions 3 and 2 for Japanese medaka (0.149 and 0.157 mM, respectively), and fractions 5 and 2 for fathead minnow (0.061 and 0.080 mM, respectively) displayed the greatest potencies for mortality (lowest LC50). When fraction LC50s for Japanese medaka were compared to the whole NAE (0.143 mM), the mid molecular weight fractions (fractions 2 and 3) appeared most similar to the whole NA. . In terms of relative toxicity and proportion, constituents in the mid molecular range fractions (2 and 3) likely represent greater risk compared to other fractions, and further chemical and toxicological characterization of constituents within these fractions is warranted particularly for long-chained, monocarboxylic acids, with low aromaticity. Japanese medaka and fathead minnow varied in their sensitivity and their relative response to different fractions. In general, fathead minnow were more sensitive than Japanese medaka based on lower estimates of LC50 and threshold (growth) values in addition to the presence of developmental abnormalities (predominately yolk sac edema) associated with a few of the fractions. Compared to differences in toxicity between fractions for a given species (>2-fold for fathead minnow), there was more variability between species for a given fraction (> 3-fold for fraction 5). Also, the relative toxicity of fractions as indicated in the present study is contrary to the results generated using Vibrio fischeri for the same fractions. Thus, there is a need for multi- endpoint and species toxicity evaluations to assess the efficacy of remediation and reclamation options for reducing toxicity of oil sands tailings

Chemical and Toxicological Characterization of Dissolved Organics from Oil Sands Waters

The surface mining of oil sands from the Athabasca deposit north of Fort McMurray, Alberta produces considerable tailings waste which is stored in large tailings ponds on industry lease sites. With the advent of oil sands end-pit lakes and decommissioned tailings ponds, viable strategies for the detoxification of oil sands process affected water (OSPW) are under investigation. One such strategy relies on the biodegradation of toxic organic compounds by indigenous microbes, resulting in aged tailings waters with potentially reduced toxicity. Determining drivers of toxicity within OSPW poses a great challenge because differences in ore quality and bitumen extraction methods influence organic and inorganic chemistry, and therefore, toxicity. In order to assess the toxic potential of the suite of dissolved organics in OSPW, a method for extraction and fractionation was developed. This was achieved with a liquid chromatography approach using reversed-phase solid phase extraction coupled with soxhlet extraction. The method successfully separated organic compounds from 180 L of an aged OSPW source into three fractions (F1-F3) with increasing polarities. Chemical characterization of the generated fractions included electrospray ionization high-resolution mass spectrometry, liquid chromatography quadrupole time-of-flight mass spectrometry, gas chromatography triple quadrupole time-of-flight mass spectrometry, and synchronous fluorescence spectroscopy. Method validation included fractionations with surrogate reference standards and labelled standards, which also confirmed separation according to polarity and verified high recovery of dissolved organics. This method was designed to generate bulk quantities of extract which provide enough material for a suite of toxicity bioassays. Using this novel method, aged OSPW and four bitumen-influenced groundwater sites (2 influenced by natural bitumen; 2 influenced by a mixture of natural bitumen and OSPW sources) were fractionated. The whole water and isolated fractions were then exposed to seven different aquatic species; Pimephales promelas (embryo), Oryzias latipes (embryo), Vibrio fischeri, Daphnia magna (neonates), Lampsilis cardium (glochidia), Lampsilis siliquiodea (glochidia) and Hyalella azteca (juveniles). Chemically, bitumen-influenced groundwater sites were predominantly composed of O2 and O4 species while aged OSPW was dominated by O4 species. Analysis also revealed a high variability in composition and abundance of organic and inorganic constituents across groundwater sites. Of the organic fractions assessed, F1 (least polar) and F3 (most polar) appeared most toxic overall while F2 displayed little toxicity to all species evaluated. Organisms were identified as differentially more sensitive to whole waters, likely as a result of inorganics (D. magna and L. siliquiodea), or dissolved organics (P. promelas and H. azteca).The present study indicates that although an aged tailings source (≥18 years) displayed low toxicity overall, inorganic and polyoxygenated organic components may pose a persistent concern to aquatic organisms. A general comparison of groundwater sites containing OSPW-derived constituents vs. natural bitumen-derived constituents revealed that whole water toxicities were quite similar. It is therefore likely that toxicity associated with tailings seepage into groundwater is mitigated by chemical changes as a result of soil composition and groundwater mixing. Finally, an ecotoxicological risk assessment of OS acid-extractable organics (AEO) produced a joint probability curve which predicted that the probability of producing an effect in 10% of fish and invertebrates species was 100% and 97.7%, respectively. In general, at AEO exposures in the range of 17 – 104 mg/L, an acute species sensitivity distribution revealed vertebrates (embryonic) to be more sensitive than invertebrate organisms. The risk assessment recommends a monitoring program that accounts for current anthropogenic dissolved organic input from tailings seepage, and its effect on particularly sensitive fish species. Additionally, future efforts regarding the wet landscape strategy should account for changes in dissolved organic concentrations and reduction in toxicity over time. In summation, for those organisms that display sensitivity to dissolved organics in oil sands waters, aging by natural biodegradation appears to be a viable strategy. Moreover, industrially-influenced groundwaters do not appear to pose a greater risk to aquatic organisms than groundwaters influenced by naturally-derived bitumen. Nonetheless, due to possible invertebrate sensitivities to inorganic components within whole waters, a strategy to deal with these bio-persistent compounds warrants investigation. In order to identify and characterize OSPW-derived dissolved organics that pose the greatest environmental risk, the bioactive fractions (F1 and F3) will be further fractionated and assessed toxicologically. Finally, it is recommended that organisms identified as being most acutely sensitive to OSPW-derived organic and inorganic constituents be the focus of future effects-directed analysis of OSPW toxicity, as well as impact assessment monitoring and future remediation/reclamation of industrial lease sites

A Preparative Method for the Isolation and Fractionation of Dissolved Organic Acids from Bitumen-influenced Waters

The surface mining of oil sands north of Fort McMurray, Alberta produces considerable tailings waste that is stored in large tailings ponds on industrial lease sites. Viable strategies for the detoxification of oil sands process affected water (OSPW) are under investigation. In order to assess the toxic potential of the suite of dissolved organics in OSPW, a method for their extraction and fractionation was developed using solid phase extraction. The method successfully isolated organic compounds from 180 L of an aged OSPW source. Using acidic- or alkaline-conditioned non-polar ENV+ resin and soxhlet extraction with ethyl acetate and methanol, three fractions (F1–F3) were generated. Chemical characterization of the generated fractions included infusion to electrospray ionization ultrahigh-resolution mass spectrometry (ESI-UHRMS), liquid chromatography quadrupole time-of-flight mass spectrometry, gas chromatography triple quadrupole time-of-flight mass spectrometry, and synchronous fluorescence spectroscopy (SFS). Additionally, ESI-UHRMS class distribution data and SFS identified an increased degree of oxygenation and aromaticity, associated with increased polarity. Method validation, which included method and matrix spikes with surrogate and labelled organic mono carboxylic acid standards, confirmed separation according to acidity and polarity with generally good recoveries (average 76%). Because this method is capable of extracting large sample volumes, it is amenable to thorough chemical characterization and toxicological assessments with a suite of bioassays. As such, this protocol will facilitate effects-directed analysis of toxic components within bitumen-influenced waters from a variety of sources

The Sydney-AAO Multi-object Integral field spectrograph (SAMI)

We demonstrate a novel technology that combines the power of the multi-object spectrograph with the spatial multiplex advantage of an integral field spectrograph (IFS). The Sydney-AAO Multi-object IFS (SAMI) is a prototype wide-field system at the Anglo-Australian Telescope (AAT) that allows 13 imaging fibre bundles ("hexabundles") to be deployed over a 1-degree diameter field of view. Each hexabundle comprises 61 lightly-fused multimode fibres with reduced cladding and yields a 75 percent filling factor. Each fibre core diameter subtends 1.6 arcseconds on the sky and each hexabundle has a field of view of 15 arcseconds diameter. The fibres are fed to the flexible AAOmega double-beam spectrograph, which can be used at a range of spectral resolutions (R=lambda/delta(lambda) ~ 1700-13000) over the optical spectrum (3700-9500A). We present the first spectroscopic results obtained with SAMI for a sample of galaxies at z~0.05. We discuss the prospects of implementing hexabundles at a much higher multiplex over wider fields of view in order to carry out spatially--resolved spectroscopic surveys of 10^4 to 10^5 galaxies.Comment: 24 pages, 16 figures. Accepted by MNRA

Spin dependent structure function g_1 at low x and low Q^2

Theoretical description of the spin dependent structure function g_1(x,Q^2) in the region of low values of x and Q^2 is presented. It contains the Vector Meson Dominance contribution and the QCD improved parton model suitably extended to the low Q^2 domain. Theoretical predictions are compared with the recent experimental data in the low x, low Q^2 region

Immunization expands B cells specific to HIV-1 V3 glycan in mice and macaques.

Broadly neutralizing monoclonal antibodies protect against infection with HIV-1 in animal models, suggesting that a vaccine that elicits these antibodies would be protective in humans. However, it has not yet been possible to induce adequate serological responses by vaccination. Here, to activate B cells that express precursors of broadly neutralizing antibodies within polyclonal repertoires, we developed an immunogen, RC1, that facilitates the recognition of the variable loop 3 (V3)-glycan patch on the envelope protein of HIV-1. RC1 conceals non-conserved immunodominant regions by the addition of glycans and/or multimerization on virus-like particles. Immunization of mice, rabbits and rhesus macaques with RC1 elicited serological responses that targeted the V3-glycan patch. Antibody cloning and cryo-electron microscopy structures of antibody-envelope complexes confirmed that immunization with RC1 expands clones of B cells that carry the anti-V3-glycan patch antibodies, which resemble precursors of human broadly neutralizing antibodies. Thus, RC1 may be a suitable priming immunogen for sequential vaccination strategies in the context of polyclonal repertoires

Color-Octet Fraction in J/Psi Production and Absorption

The cross section between a $c \bar c$ pair and a nucleon is small and sensitive to the $c - \bar c$ separation if the pair is in a color-singlet state, but very large and insensitive to the separation if it is in a color-octet state. We use this property in an absorption model involving both color components to deduce the color structure of $c \bar c$ pairs produced in $p(B)A \to \psi X$ reactions. Our analysis shows that the NA3, NA38 and E772 data are not inconsistent with the theoretical picture that color-octet and color-singlet precursors are produced in roughly equal proportions if the produced color-singlet precursors are pointlike and transparent. However, if the color-singlet precursors are not transparent but have a cross section of a few mb, these data do show a definite preference for a larger fraction of color-singlet precursors. In either case, the color-octet fraction increases with $x_F$, approaching unity as $x_F$ becomes large.Comment: 9 pages, updated to include new result

Measurement of the Proton and Deuteron Spin Structure Function g_1 in the Resonance Region

We have measured the proton and deuteron spin structure functions g_1^p and g_1^d in the region of the nucleon resonances for W^2 < 5 GeV^2 and $Q^2\simeq 0.5$ and $Q^2\simeq 1.2$ GeV^2 by inelastically scattering 9.7 GeV polarized electrons off polarized $^{15}NH_3$ and $^{15}ND_3$ targets. We observe significant structure in g_1^p in the resonance region. We have used the present results, together with the deep-inelastic data at higher W^2, to extract $\Gamma(Q^2)\equiv\int_0^1 g_1(x,Q^2) dx$. This is the first information on the low-Q^2 evolution of Gamma toward the Gerasimov-Drell-Hearn limit at Q^2 = 0.Comment: 7 pages, 2 figure

Configuration and Assessment of the GISS ModelE2 Contributions to the CMIP5 Archive

We present a description of the ModelE2 version of the Goddard Institute for Space Studies (GISS) General Circulation Model (GCM) and the configurations used in the simulations performed for the Coupled Model Intercomparison Project Phase 5 (CMIP5). We use six variations related to the treatment of the atmospheric composition, the calculation of aerosol indirect effects, and ocean model component. Specifically, we test the difference between atmospheric models that have noninteractive composition, where radiatively important aerosols and ozone are prescribed from precomputed decadal averages, and interactive versions where atmospheric chemistry and aerosols are calculated given decadally varying emissions. The impact of the first aerosol indirect effect on clouds is either specified using a simple tuning, or parameterized using a cloud microphysics scheme. We also use two dynamic ocean components: the Russell and HYbrid Coordinate Ocean Model (HYCOM) which differ significantly in their basic formulations and grid. Results are presented for the climatological means over the satellite era (1980-2004) taken from transient simulations starting from the preindustrial (1850) driven by estimates of appropriate forcings over the 20th Century. Differences in base climate and variability related to the choice of ocean model are large, indicating an important structural uncertainty. The impact of interactive atmospheric composition on the climatology is relatively small except in regions such as the lower stratosphere, where ozone plays an important role, and the tropics, where aerosol changes affect the hydrological cycle and cloud cover. While key improvements over previous versions of the model are evident, these are not uniform across all metrics

Propagation of Muons and Taus at High Energies

The photonuclear contribution to charged lepton energy loss has been re-evaluated taking into account HERA results on real and virtual photon interactions with nucleons. With large $Q^2$ processes incorporated, the average muon range in rock for muon energies of $10^9$ GeV is reduced by only 5% as compared with the standard treatment. We have calculated the tau energy loss for energies up to $10^9$ GeV taking into consideration the decay of the tau. A Monte Carlo evaluation of tau survival probability and range show that at energies below $10^7-10^8$ GeV, depending on the material, only tau decays are important. At higher energies the tau energy losses are significant, reducing the survival probability of the tau. We show that the average range for tau is shorter than its decay length and reduce to 17 km in water for an incident tau energy of $10^9$ GeV, as compared with its decay length of 49 km at that energy. In iron, the average tau range is 4.7 km for the same incident energy.Comment: 25 pages including 8 figure