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Passive sampling, as opposed to the conventional spot or bottle water sampling technique, has shown to be reliable and efficient in monitoring the toxicologically relevant, freely dissolved (e.g. bioavaialable) concentrations of a wide range of organic contaminants in water. At the same time, partitioning controlled delivery (passive dosing; PD) techniques promise to overcome many of the challenges associated with toxicity testing of hydrophobic substances that may bias the interpretation of toxicity data. The present study investigated the feasibility of coupling silicone rubber passive sampling devices (SR-PSDs) with bioassay techniques for both chemical and ecotoxicological assessment of complex mixtures of organic contaminants in the aquatic environment. SR-PSDs were deployed in water at various locations within the Ythan catchment (north east, Scotland, UK), Forth estuary and the Firth of Forth (east coast of central Scotland, UK) for 7 to 9 weeks. Following retrieval, extracts from the SR-PSDs were analysed for dissolved concentrations of a variety of organic contaminants including PAHs and PCBs using GC-MS and GC-ECD respectively and were screened for a wide range of pesticides using GC-MS/MS and LC-MS/MS. The extracts were further evaluated for acute cytotoxicity (i.e. neutral red uptake assay) and EROD induction potential using rainbow trout liver cell line (Oncorhynchus mykiss; RTL-W1) and for phytotoxicity and developmental toxicity potential using algal growth inhibition test (with a marine phytoplankton, Diacronema lutheri) and fish embryo toxicity test (with embryos from zebrafish Danio rerio) respectively. Overall, the individual and total dissolved concentrations of PAHs (ΣPAH40; parent and branched) and PCBs (ΣPCB32; ortho and mono-ortho) measured in water from the Ythan, Forth estuary and Firth of Forth were relatively low compared with other studies using PSDs. A number and level of pesticides, including insecticides, herbicides and fungicides of varying hydrophobicity (log KOWs ~2.25 to ~5.31) were detected in the silicone rubber (SR) extracts from the Ythan catchment, the Forth estuary and the Firth of Forth, suggesting input mainly from agricultural run-off and possibly from direct discharges. No statistically significant (p<0.05) acute cytotoxicity was observed following 48 h exposure of RTL-W1 cells to SR extracts from the Ythan catchment. But, on a sublethal level, for every site, statistically significant EROD activity was observed to some degree following 72 h exposure. In addition, developmental and algal toxicities on embryos of D. rerio and D. lutheri respectively, were measured in all the deployed samples compared with the procedural controls (undeployed samples). Interestingly, extracts of SR-PSDs from the Forth estuary and the Firth of Forth exhibited growth inhibitions on D. lutheri that were similar to those of extracts from the Ythan, even though, fewer numbers of pesticides were detected in the Forth estuary and Firth of Forth than the Ythan. This suggests that pesticides were not solely responsible for the observed effects in the Ythan catchment. To further improve data from toxicity testing of hydrophobic substances, the study identified the use of SR O-rings as a suitable passive dosing format in in vitro toxicity tests and was partially validated through their use in dosing RTL-W1 cells with two individual PAHs and subsequently determining cytotoxicity and EROD-activity.

Exogenous zinc has been shown to alter the cellular response to inflammatory conditions. Both common zinc salt and novel zinc compounds have been shown to be therapeutic in various disease states. However, little is known about their action on immune cells in these conditions. This thesis aims to investigate the effectiveness of zinc monoglycerolate (ZMG), a novel zinc compound, in providing bioavailable zinc. This study also aims to examine the effect of zinc on the inflammatory responses of immune and gastric cells. Using cell culture techniques, fluorescence microscopy and inductively coupled plasma mass spectroscopy (ICP-MS), comparison was made of zinc bioavailability from ZMG, zinc oxide and zinc sulphate. The cellular protein interactions of the zinc provided by these compounds was investigated by autoradiography, Western blot analysis and cytokine assay. As a result of the biological study, chemical analyses were carried out on ZMG using high performance liquid chromatography (HPLC), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and matrix assisted laser desorption ionisation time of flight (MALDI-ToF).The result of the cell culture study indicated that ZMG and zinc oxide provided significantly more bioavailable zinc than zinc sulphate. Furthermore, these results showed that the different cell lines examined treated the zinc in distinctly different manners. The studies on direct zinc-protein interactions did not conclusively determine whether such interactions occurred between cytoplasmic proteins and exogenous zinc. However, zinc was shown to modulate cytokine secretions in vitro in cultured cell lines. The chemical analyses provided novel observations about the polymeric structure of ZMG and its solubility profile. In conclusion the results showed that ZMG is a highly effective source of bioavailable zinc and that exogenous zinc can modulate the immune response of cultured cell lines to external stimuli.

Abstract: Bromacil and tebuthiuron are herbicides used from the 1960s to 1990s on industrial sites to control vegetation. Approximately 61,750 sites are considered contaminated when comparing total herbicide concentrations (estimated by 99 percent methanol extraction) against Alberta’s remediation guidelines. Remediation of these sites requires treatment or removal of soil to bring herbicide concentrations below applicable guidelines. As time passes from initial application, a portion of bromacil and tebuthiuron is thought to adsorb to the soil solid phase. The total herbicide concentration in soil is then comprised of the adsorbed (solid phase) and the phytoaccessible (plant accessible) concentrations. Measuring phytoaccessible or soluble herbicide concentrations in soil would avoid unnecessary ex-situ treatment or landfilling. It is likely that adsorption to soil organic matter or mineral particles reduces phytoaccessibility and immobilization technologies could be used to increase the natural soil adsorptive capacity to manage in-situ sites with herbicide contamination. Calcium chloride solution (0.01 M) is often used to assess soluble (phytoaccessible) concentrations of nutrients and to conduct adsorption/desorption studies of metals and organics. In this work, it was used as an extractant to estimate the phytoaccessible concentrations of bromacil and tebuthiuron in soil. A t-test for non-parametric data with homogeneous variances was used to compare calcium chloride-extractable herbicide concentrations to total concentrations (estimated by 99 percent methanol extraction of aged soil samples, or by spiking soils using a known herbicide concentration). For this study, 149 x 1 g soil samples were included containing a known concentration of bromacil (84 samples) or tebuthiuron (66 samples). Samples were extracted with 40 mL 0.01 M calcium chloride by shaking and centrifugation. The resulting 10 mL liquid extracts were sent to a commercial laboratory for analysis with High Pressure Liquid Chromatography (HPLC) using Mass Selective Detection. Estimated total concentrations were higher than calcium chloride-extractable concentrations. Median spiked and aged bromacil concentration was 0.300 mg/kg and median calcium chloride-extractable bromacil was 0.190 mg/kg (W = 5131, p < 0.001). Median spiked and aged tebuthiuron concentration was 0.273 mg/kg and median calcium chloride-extractable was 0.140 mg/kg (W = 2694, p = 0.003). In reviewed literature, organic matter and clay contribute most to bromacil or tebuthiuron adsorption. Categorical analysis of high or low organic matter and high or low clay content against the apparently adsorbed fraction was conducted. A two-by-two Analysis of Variance (ANOVA) assessed if increasing percentage of clay and organic matter increased the apparently adsorbed fraction, which was estimated by subtracting the calcium chloride-extracted concentration from the total estimated concentration. Mean apparently adsorbed bromacil fraction was higher for high organic matter compared to low organic matter soils (F = 8.09, p < 0.01). Clay did not significantly increase apparent bromacil adsorption (F = 2.36, p = 0.133). Similarly, mean apparent adsorbed tebuthiuron fraction was significantly higher for high organic matter compared to low organic matter soils (F = 25.89, p < 0.001), but clay did not significantly increase tebuthiuron adsorption (F = 0.03, p = 0.858). Calcium chloride-extracted concentrations of bromacil and tebuthiuron were less than the estimated total concentrations likely due to adsorption on organic matter. Where there are large areas of marginal bromacil or tebuthiuron contamination, approaches are needed to reduce risk, meet regulatory requirements, and protect soil health. Soils with low phytoaccessible concentrations could remain in place and retain nutrients, organic matter, and structure, providing resiliency against current and future challenges to soil ecosystems.

A new, reversible photochemical transformation of V(V) tartrate clusters into V(IV) tartrate is described. While the initial V(V) tartrate cluster and photoproduct are known, this research uncovers a previously unreported photochemical transformation. Irradiation of V(V) tartrate in buffer at pH 5.8 showed color changes from orange yellow through a green intermediate to purple, developing a UV-vis spectrum characteristic of V(IV) tartrate. X–ray crystallography revealed an initial tetranuclear Na5[V4O8(2R,3R–tart) (2S,3S–tart)] •11H2O, and final photoproduct in solution which crystallized to a Na4[(VO)2(2R,3R–tart) (2S,3S–tart)] •12H2O dimer. EPR spectroscopy confirmed the reduction from diamagnetic V(V) to paramagnetic V(IV) photoproduct. CO2 was also produced during photolysis, indicating oxidation of the tartrate ligand during photolysis. These results highlight how light irradiation tunes the oxidation state of V(V/IV) clusters and thus these species have the potential to control the reactivity of these vanadium-based catalysts using light.Incorporation of the transition metal V(V) into hydrogels has been used to impart photo-responsive behavior which was used to tune materials properties during light irradiation. The photoreaction in the cellulose-agarose hydrogels coordinated with vanadium was evidenced by a clear color change of yellow to blue through a green intermediate. This color change was attributed to the reduction of V(V) to V(IV) as described above. A concomitant oxidative breakdown of the polysaccharide chain was noticeable upon the reduction of V(V) with a decrease in stiffness (G’) of the hydrogel material. This reduction of the metal ion and breakdown of polysaccharide chain induce irreversible changes in the microstructure of the hydrogel which enables the controlled delivery of V(IV) and/or encapsulated cargo. Polyaniline (PANI) is a famous conductive polymer. When V(V) was reduced to V(IV) upon irradiation, this ultimately causes an oxidative polymerization for polyaniline on hydrogels. Thus, we have developed conductivity in cellulose-agarose hydrogels with the light responsive properties of vanadium. Thus, we explained the photochemistry in vanadium tartrate clusters and developed interesting macroscopic effects with the light responsive properties of vanadium at the molecular level.

Abstract: Surface mining for bitumen extraction results in production of tailings that are deposited into large ponds. Tailings in the ponds support diverse microbial communities capable of metabolizing organic compounds and producing biogenic gases (methane, CH4 and carbon dioxide, CO2). Because of low endogenous concentrations of bioavailable nitrogen (N), tailings ponds might be deficient in available N (NO3-/NH4+). This study examined the potential of N2-fixation mediated methanogenic degradation of citrate and petroleum hydrocarbons in oil sands tailings under N-depleted conditions. Anaerobic primary cultures were set up with available N or N-deficient medium under N2 headspace using mature fine tailings (MFT) and amended with citrate as a carbon source. Citrate was metabolized to CH4 under both N available and deficient conditions suggesting N2-fixation mediated degradation of citrate. Acetylene reduction assay and incorporation of 15N2 stable isotope into microbial biomass supported N2-fixation during citrate metabolism.

Anion exchange methods were used to measure the percent of weakly bound and strongly bound copper in estuarine waters and agricultural drainage. Copper bound to an ion exchange resin has been operationally defined as bioavailable copper, or copper that is available for uptake by aquatic organisms. Initial laboratory testing indicated that the percent of copper bound to the resin did not differ between a freshwater solution (pH 6.5 buffered with 30 mg/L as calcium carbonate) and a saline solution (25 ppth salinity at pH 8). Adding 20 mg/L natural organic matter (NOM) to each solution lowered the amount of copper sorbed to the resin by the same amount in saline and fresh water. Varying salinity from 16 to 30 ppth did not effect % bioavailability. This indicates that the ions typically found in seawater do not compete with copper for ion exchange onto the resin. Varying initial copper concentration from 195 to 495 ppb for the given NOM content of 12.5 mg/L did not effect % bioavailability, indicating that as the copper concentration of this water is increased over the range studied, the fraction of potentially toxic copper is constant. Decreasing the pH of the system from 8.5 to 4 and the NOM from 12.5 to 0 mg/L statistically increased % bioavailability in both cases. However, copper retention onto the resin at pH values near 4 was hindered, possibly because resin functional groups become inefficient at low pH values. MINEQL+ predicted that the resin was not retaining approximately 30% Cu+2 at a pH of 4. Copper retention to the resin was also not as high as expected at NOM contents between 0 and 3 mg/L at pH 8.1. MINEQL+ indicated that the water studied at pH 8.1 was comprised primarily of strongly bound copper-organic ligand species and Cu(OH)2. Experimental results suggested that the resin retained only 50% Cu(OH)2, which is a potentially bioavailable copper complex. However, MINEQL+ computer modeling indicated that the resin was accurately retaining potentially bioavailable copper in waters with a pH from 5.5 to 8.5, containing 3 to 12.5 mg/L NOM. After assessing the characteristics of copper retention by the resin, it was applied to an estuarine system and agricultural drainage to measure bioavailable copper. The results indicated that in copper-containing agricultural runoff and groundwater the percent bioavailable copper was approximately 15% of the dissolved copper. This percentage was relatively constant over the range of copper concentrations observed. In estuarine systems receiving agricultural runoff, the percent bioavailable copper was about 11%. This research was supported by a grant from the Virginia Pesticide Control Board.