Chlorine stable isotope analysis (?37Cl ) means of stream water (- 0.95 ‰, n = 22), rainwater (- 1.51 ‰, n = 12), fog water (- 1.08 ‰, n = 7) and silicate mineral bound chloride (+ 0.13 ‰, n = 3) are used in an isotope mass balance approach to estimate sources of stream chloride. During summer-baseflow conditions, the chloride budget of two catchments in southwestern Nova Scotia is approximately 39 % from rainfall, 37 % from fog water and 24 % from rock/water interactions. The results of a significant source of geological chloride suggest the use of chloride in stream water as a proxy for marine derived sulphate may not be valid. This conclusion implies that anthropogenic sources of sulphate to acid sensitive ecosystems of southwestern Nova Scotia have been underestimated when chloride is assumed to be a conservative ion in the hydrological cycle.

A new treatment technology, called Advanced Reduction Process (ARP), was developed by combining UV irradiation with reducing reagents to produce highly reactive species that degrade contaminants rapidly. Vinyl chloride (VC) and 1,2-dichloroethane (1,2-DCA) pose threats to humans and the environment due to their high toxicity and carcinogenicity. In this study, batch experiments were conducted under anaerobic conditions to investigate the degradations of VC and 1,2-DCA with various ARP that combined UV with dithionite, sulfite, sulfide or ferrous iron. Complete degradation of both target compounds was achieved by all ARP and the reactions were found to follow pseudo-first-order decay kinetics. The effects of pH, sulfite dose, UV light intensity and initial contaminant concentration on the degradation kinetics were investigated in the photochemical degradation of VC and 1,2-DCA by the sulfite/UV ARP. The rate constants were generally promoted by raising the solution pH. The optimal pH conditions for VC and 1,2-DCA degradation were pH 9 and pH 11,respectively. Higher sulfite dose and light intensity were found to increase the rate constants linearly for both target contaminants. A near reciprocal relation between the rate constant and initial concentration of target compounds was observed in the degradation of 1,2-DCA. The rate constant was observed to be generally independent of VC concentration, but with a slight increase at lower concentrations. A degradation mechanism was proposed that described reactions between target contaminants and reactive species such as the sulfite radical and hydrated electron that were produced in the photolysis of sulfite solution. A mechanistic model that described major reactions in the ARP system was developed and explained the dependence of the rate constant on those experimental factors. Chloride ion and chloroethane were detected as the major degradation products at acid and neutral pH. An increase in pH promoted the extent of dechlorination with complete dechlorination being observed at pH 11 for both VC and 1,2-DCA. Due to the rapid degradation kinetics in these ARPs, this new treatment technology may be applied to remove various contaminants in water and wastewater.

The lower esophageal sphincter (LES) is characterized by basal tone and appropriately timed neurogenic relaxation. The physiological mechanisms underlying these crucial LES functions remain poorly understood. The current studies were designed to characterize the electrophysiological properties and neural regulation of LES circular smooth muscle (CSM), and to determine whether interstitial cells of Cajal (ICC) play a role in neurotransmission. Conventional intracellular recordings were performed in CD1, nNOS knock-out, eNOS knock-out and W/Wv mutant mice. Mouse LES consists of “sling” and “clasp” smooth muscle, which were studied separately in CD1 mice. In subsequent studies of mutant mice and respective controls, only the clasp muscle was examined, Immunohistochemical c-Kit staining of ICC was performed in wild-type and W/Wv mutant mice that were first characterized electrophysiologically. The smooth muscle of the LES clasp and sling displayed unitary membrane potentials with a resting membrane potential (RMP) of ~ -43 mV. Spontaneous nifedipine-sensitive action potentials superimposed on the unitary potentials were usually recorded in the LES clasp, but not sling muscle. A monophasic inhibitory junction potential (IJP) was recorded in sling CSM, whereas a biphasic IJP consisting of an initial IJP, followed by long-lasting slow IJP (LSIJP) was recorded in clasp. Further pharmacological studies using control and various knockout mice suggest that: 1. the CSM of the mouse LES is innervated by cholinergic, nitrergic and purinergic nerves; 2. the LSIJP is mediated entirely by nitrergic nerves, whereas purinergic and nitrergic nerves produce the monophasic IJP in the LES sling and initial phase of biphasic IJP in the LES clasp; 3. Ca2+/CaM-kinase II is involved in the regulation of the nitrergic IJPs; 4. TREK-1 K+ channels are not involved in the nitrergic IJP; 5. purinergic and cholinergic neurotransmission is intact in LES CSM of W/Wv mutant mice, whereas nitrergic neurotransmission is impaired in about half of the animals. In animals in which nitrergic neurotransmission was intact, ICC-IM were markedly deficient immunohistologically, suggesting that ICC are not required for nitrergic neurotransmission; 6. impaired nitrergic neurotransmission in W/Wv mutant mice is associated with dysfunction of a Ca2+-dependent signaling cascade primed by spontaneous Ca2+ release from the sarcoplasmic reticulum. / Thesis (Ph.D, Physiology) -- Queen's University, 2008-01-24 15:54:52.175

Hydrochloric acid leaching of saprolite nickel ores has been proposed as an effective means of recovering nickel and cobalt. However, the leach produces a concentrated brine of magnesium chloride which must be hydrolyzed to recover the HCl lixiviant. The processing of carnallite similarly produces a concentrated MgCl2 brine; converting this brine into HCl and MgO provides an attractive way of adding value while effectively disposing of this waste product. Direct pyrohydrolysis of magnesium chloride brines by the reaction, MgCl2,a + H2Oa  MgOs + 2HClg is energy-intensive as large volumes of water must be evaporated. The energy cost is high, and the HCl stream produced is limited to approximately 20 wt% HCl. This thesis explores alternative methods of obtaining HCl from aqueous magnesium chloride solutions. Two methods are considered: the hydrolysis, under autogenous pressure, of concentrated MgCl2 molten salt hydrates; and the precipitation of magnesium hydroxychloride compounds such as 2MgO·MgCl2·6H2O and 3MgO·MgCl2·11H2O, which are subsequently decomposed at high temperature. Considerable experimental difficulties were encountered in studying pressure hydrolysis of molten salt hydrates, despite extensive equipment modifications. Ultimately, the work moved on to precipitation and decomposition of hydroxychlorides. This was found to bear promise, and conceptual flowsheets based on these reactions are presented. A phase stability diagram giving the areas of predominance of the different hydroxychloride phases is presented, and fundamental thermochemical data are derived. The results of a kinetic study on magnesium hydroxychloride thermal decomposition are also presented. / Thesis (Ph.D, Mining Engineering) -- Queen's University, 2011-03-11 10:14:53.455

The objectives of this study are to estimate the degree to which a glutamate-gated chloride channel gene (HcGluCla) contributes to survival of moxidectin treatment and to study the relative dominance of those alleles. The phenotype of individual adult H. contortus with respect to feeding was determined using an inulin uptake assay. Genotype was determined using a diagnostic PCR assay. In the absence of moxidectin, homozygous susceptible genotypes fed significantly more than homozygous resistant genotypes. The effect of the susceptible allele was dominant. In the presence of moxidectin, feeding in the susceptible homozygotes was reduced to the level found in the resistant homozygotes, which were unaffected by the drug. These results suggest that the function of the two alleles is different and that they also respond differently to the drug, the resistant allele being unaffected by the drug. / The selection coefficient, s, is the selective difference between the resistant and susceptible genotypes with regard to feeding. Parasites with the resistant allele were seen to feed less in the absence of the drug, i.e., the effect is recessive. In the presence of the drug, there was no difference between resistant and susceptible parasite feeding. These results suggest that resistance may have hidden complexities. (Abstract shortened by UMI.)

The anti-nematodal drug ivermectin hyperactivates invertebrate-specific glutamate-gated chloride channels (GluCls) causing pharyngeal paralysis and a cessation of feeding and growth. I find that for C. elegans even brief exposure to ivermectin can lead to irreversible pharyngeal paralysis. Ivermectin induces heterogeneous vacuolation in the pharynx that appears slowly and accumulates over several days. This vacuolation is almost completely rescued by a mutation in avr-15, which codes for the alpha-subunit of pharyngeal GluCls. The vacuoles stain strongly with Lysotracker Red and are therefore likely to be acidic compartments of the endosomal-lysosomal system. Examination of mutants defective for endocytosis (rme-1, rme-8, and cup-5) uncovers the presence of acidic vacuoles identical in appearance to ivermectin-induced vacuoles. Further, RME-1, a marker for recycling endosomes, is shown to redistribute soon after ivermectin exposure. Examination of the effects of ivermectin on extrapharyngeal neurons expressing ectopic avr-15 reveals an apoptotic phenotype that is shown to be ced-independent.

Swine slurry is a source of nutrients to grasslands. However, accumulation of N or P can lead to their movement to groundwater. This thesis’ research was conducted using a tame pasture fertilized over six years with swine slurry at N-requirement rates, on a gravelly soil in south-eastern Manitoba. Objectives were to determine N and P soil surplus and accumulation over time, soil profile P fractions and soil surface P saturation, and nitrate and dissolved-P in shallow groundwater for treatment combinations of forage utilization (Hay and Grazed), slurry application in spring (Single), split in fall and spring (Split) and no slurry (Control), and Grassed areas of grazed paddocks and Bare areas where cattle congregated around water troughs. There were less surplus and accumulation of extractable-P in the soil surface for the Split compared to the Single treatment because of less P in fall- than in spring-applied manure. With Grazing, there were greater surpluses of N and P than with Haying, and surface accumulation of extractable-P over time was linear being 16.5 and 11.9 mg P kg-1 year-1at 0-5 cm for Grazed and Hay treatments, respectively. Labile inorganic-P fractions (water- and bicarbonate-extractable) increased in the Bare and in the Single Grassed treatments. In the Bare treatment, P-sorption capacity at 0-5 cm decreased compared to the Grassed treatment. The surface soil of the Bare areas had large concentrations of water-soluble-P up to 165 mg P kg-1 associated with an increase in P-saturation to 88 % of the sorption capacity, and nitrate was elevated in the soil profile. Concentrations of nitrate-N and dissolved-P in groundwater were below the environmental thresholds of 10 mg nitrate-N L-1 and 0.025 mg P L-1, respectively, in both the Hay and the Grazed Grassed treatments. In contrast, the Control and Single Bare treatments had nitrate concentrations always above the threshold, and the Bare areas in the Single paddocks had P concentrations of environmental concern in 2009, averaging 0.7 mg total dissolved P L-1. Nitrogen-based slurry applications did not cause leaching of N or P, but Bare areas in grazed pastures are at risk of N and P leaching.

Onchocerca volvulus, a filarial nematode, is the causative agent of onchocerciasis. / O. volvulus is a human parasite with no animal model host and is endemic in the tropics. O. volvulus material is scarce and must be conserved as part of the Onchocerciasis Control Program. A genomic library was constructed to provide a substantial source of renewable genetic material, in place of original parasite DNA. / Currently there is only one glutamate-gated chloride channel that has been sequenced from O. volvulus, but this has not yet been characterized. This GluClx partial cDNA sequence isolated by Cully et al., 1997, may be found in GenBank, accession number U59745. Specific primers were designed to amplify this gene from the genomic library. A fragment of this gene was isolated but the primers were non-specific, amplifying genes in addition to GluClx. / A motif is a short recognition sequence within a protein that may allow the modification of the protein. The cysteine loop in the N-terminal of all the ligand-gated ion channels is interesting because it contains the neurotransmitter-gated ion channel signature sequence. (Abstract shortened by UMI.)

In embryonic neurons, the intracellular chloride concentration is elevated, making GABA and glycine depolarizing. Later in development, coincident with neuronal maturation, the extruding potassium-chloride co-transporter KCC2 is expressed. It reverses the chloride gradient, rendering it hyperpolarizing. Early depolarization is assumed to play trophic roles during nervous system development. I thus decided to investigate the effects of the depolarizing chloride gradient on development in vivo in the zebrafish embryo. I first determined the temporal pattern of KCC2 expression in zebrafish and found it was absent in the embryo. I then over-expressed wild-type, gain-of-function and loss-of-function variants of human KCC2, using GFP-tagged constructs for detection purposes. Over-expression of functional hKCC2 perturbed the morphology and motor behaviours of the embryos. At the cellular level, KCC2 impaired axonal growth and affected the neuronal populations in the brain, hindbrain and spinal cord. This suggests the depolarizing effects of glycine are critical for neurogenesis.

Isotopes and hydrochemistry were used to define groundwater flow systems and better understand the hydrogeological setting of the Karijini National Park within the Central Pilbara region, this study was initiated because of the near proximity of the Marandoo iron ore mine to the National Park. Based on the stable isotope composition of the water samples, two main groups of water can be identified. Groundwater is characterised by depleted δD and δ¹⁸O, suggesting no significant evaporation effect. Surface water on the other hand is more enriched in δD and δ¹⁸O due to evaporation. The relatively high concentration of Cl- compared to rainfall and depleted δD and δ¹⁸O values of groundwater indicate that recharge of the aquifers is occurring during intense rainfall events when rapid infiltration occurs. Evapotranspiration then acts to concentrate ionic species prior to recharge. The presence of CFCs in the groundwater indicates the presence of modern recharge water. Relationships between various ionic species has shown that infiltration through the Tertiary sequence and subsquent dissolution of carbonate minerals is main influence on increasing concentrations of Ca²⁺ , Mg²⁺ , HCO₃⁻ . The TDS concentration of the groundwater in the Marra-Mamba Iron Formation that hosts the Marandoo ore body is higher than most of the water bodies surrounding the mining area. This suggests that either significant chemical modification is occuring or it is recharged by different mechanisms to that of the Karijini groundwater. Relationships between the major ion concentration and catchment area, surficial Tertiary cover and distance between recharge and discharge were identified. The results show that the hydrochemistry of the water discharging at each location within the National Park can be justified by groundwater evolution within it’s own catchment.