Volatile trace metals are variably enriched in volcanic gases. Metal concentrations in sub-aerially erupted magmas are also depleted in many of these metals. The causes of variable metal enrichment in volcanic gasses, however, remain enigmatic. The objective of this work is to place experimental constraints on kinetic and thermodynamic factors that influence the concentrations of trace metals in volcanic gases. To measure metal mobility in silicate melts, Pt crucibles packed with metal doped glasses of broadly basaltic composition were equilibrated with air and mixed gases at atmospheric pressure. The metals in the melt diffused to the gas/melt interface where they were released as a volatile species. The experiments produced concentration-distance profiles from which diffusivity was derived. Experiments were also conducted in a piston-cylinder apparatus at 1 GPa pressure. In these experiments, melts were equilibrated with Cl-bearing fluids at high temperature and pressure. At equilibrium, trace metals partitioned between the melt and fluid phase as a function of temperature and fluid composition. The diffusivity of Re in melts of natural basalt, andesite and a synthetic composition in the CaO-MgO-Al2O3-SiO2 (CMAS) system has been investigated at 0.1 MPa and 1250-1350C over a range of fO2 conditions from log fO2 = -10 to –0.68. Re diffusivity in natural basalt at 1300C in air is logDRe = -7.2  0.3 cm2/sec and increases to logDRe = -6.6 0.3 cm2/sec when trace amounts of Cl were added to the starting material. At fO2 conditions below the nickel-nickel oxide (NNO) buffer Re diffusivity decreases to logDRereducing = -7.60.2 cm2/sec and to logDReandesite = -8.4  0.2 cm2/sec in andesite melt. Cd, Re, Tl, Pb, Sb and Te diffusivity in CMAS and Na2O-MgO-Al2O3-SiO2 (NMAS) melts were also determined at 0.1 MPa and 1200-1350C. In the CMAS composition at 1300C, the fastest diffusing element was Cd having a logDCd = -6.5  0.2. The slowest element was Re with logDRe = -7.5  0.3. Diffusivities of Sb, Te, Pb and Tl have intermediate values where logDSb = -7.1  0.1, logDTe = -7.2  0.3, logDPb = -7.1  0.2, logDTl = -7.0  0.2 cm2/sec. In the NMAS composition, logDRe = -6.5  0.2, logDSb = -6.0  0.2, logDPb = -6.1  0.1, logDTl = -5.8  0.2 cm2/sec. Fluid/melt partition coefficients ( ) of Re, Mo, W, Tl and Pb between fluid (H2O + Cl) and a haplobasaltic melt in the CMAS system were measured between 1200 and 1400°C at 1 GPa and fluid chlorine molarities from 7.7 to 27 mol/L. At 1300°C and fluid molarity of 7.7 mol/L, = 9.8±1.8, = 11.8±1.6, = 3.7±1.6, = 4.5±1.4 and = 2.4 ±1.8. Both Mo and Re were shown to partition most strongly into the fluid at all temperatures and fluid chlorinities. Differences in diffusivity of volatile heavy metal ions to a lead to significant fractionation between these metals in magmas during degassing. Given the observed differences in Cd and Re diffusivities, an increase in the normalized Cd/Re ratio in the gas phase with increasing bubble growth rate is predicted. Monitoring of the Cd/Re ratios in aerosols from degassing volcanoes may provide a tool for predicting volcanic eruption. Modeling of Re using the values measured here support the contention that subaerial degassing is the cause of lower Re concentrations in arc-type and ocean island basalts compared to mid-ocean ridge basalts. The model results were also compared with emanation coefficients for trace metals from natural volcanoes. The magnitudes of the modeled Re/Tl and Re/Pb in fluids at 1300C and the lowest fluid chlorinities were less than that observed from their emanation coefficients. Re and Pb are more sensitive to fluid chlorinity than Tl. The ratios of Re/Tl and Re/Pb expected from emanation coefficients are closely matched if partitioning values for experiments having fluid chlorinities of ~16-20 MCl at 1300C are used.

With an increasing number of large area data sets, many study areas exhibit spatial non-stationarity or spatial variation in mean and variance of observed phenomena. This poses issues for a number of spatial analysis methods which assume data are stationary. The Getis and Ord’s Gi* statistic is a popular measure that, like many others, is impacted by non stationarity. The Gi* is used for locating hot and cold spots in marked data through the detection of spatial autocorrelation in values that are extreme relative to the global mean value, or the mean entire study area. This thesis describes modifications of the Getis and Ord’s Gi* local measure of spatial association, in part to account for regional differences (spatial non-stationarity) in a dataset. Instead of using data from the entire study area to calculate the mean parameter, as is done for the standard Gi*, I capture points for calculation of the mean using a circular distance band centred on the pivot location, which I call the local region (similar to the Ord and Getis Oi statistic). This approach can be applied to a single instance of a local region or to multiple spatial scales of the local region. I explore both in this paper using simulated datasets and a case study on mountain pine beetle infestation data. I find that the local region, when of a similar size to a true region (homogeneous section of the study area where the mean is approximately the same across locations), obtains similar results to the standard Gi* calculated separately on distinct regions (simulated to be distinct), but has the advantage of not needing explicit delineation of regional boundaries or partitioning into separate subareas. The results of a probability score for a multi-scale approach include high and low scores that are more evenly distributed across the study area and that are thus able to pick out more subtle variations within different regions. Through the case study I demonstrate how the multi-scale approach may be applied to a real dataset.

Considering the recent losses observed in Arctic sea-ice and the anticipated future warming due to anthropogenic greenhouse gas emissions, sea-ice retreat in the Canadian Arctic Archipelago (CAA) is expected. As most global climate models do not resolve the CAA region, a fine-resolution regional model is developed to provide a sense of possible changes in the CAA sea-ice. This ice-ocean coupled model is forced with atmospheric data for two time-periods. Results from a historical run (1950-2004)are used to validate the model. The model does well in representing observed sea-ice spatial and seasonal variability, but tends to underestimate summertime ice cover. In the future run (2041-2060), wintertime ice concentrations change little, but the summertime ice concentrations decrease by 45%. The ice thickness also decreases, by 17% in the winter, and by 36% in summer. Based on this study, a completely ice-free CAA is unlikely by the year 2050, but the region could support some commercial shipping.

The episodic tremor-and-slip (ETS) events refer to the concurrence of westward crustal movements, as evident by GPS observations, and tremor-like seismic activity in the northern Cascadia margin. The regular occurrence of ETS events in the region has been remarkable. In addition to the 14-month period, secondary tremor activities, most of them lasting less than one or two days, are also found with no corresponding GPS signatures. However, the identification of tremor activity is mainly based on visual examination of regional/Iocal seismic records. In this study, we attempt to develop an algorithm that can quantitatively characterize the level of tremors from a collection of seismic waveform data. For each hour of waveform at a given station, the process begins with the calculation of moving average and scintillation index with various time lengths. The scintillation index, essentially the "normalized variance of intensity of the signal", is adapted from the studies of pulses in radio waves and is an efficient tool to identify the pulse-like characteristics of tremor signals. Values of the indices are fed into a series of logic gates that use a combination of both parameters to determine if sufficient tremor activity exists. To demonstrate the effectiveness of our algorithm, seismic waveform data are collected for the known February/March 2003 ETS event. Our analysis gives results consistent with the work done manually. Implementation of our algorithm is straightforward and free from human intervention. Thus, it is potentially possible to automate the tremor monitoring process that may give early warning of the exact arrival time of ETS events.

Propagation and reverberation of acoustic fields in shallow water depend strongly on the spatial variability of seabed geoacoustic parameters, and lack of knowledge of seabed variability is often a limiting factor in acoustic modelling applications. How-ever, direct sampling (e.g., coring) of vertical and lateral variability is expensive and laborious. and matched-field and other long-range inversion methods fail to provide sufficient resolution. This thesis develops a new joint time/frequency domain inversion for high-resolution single-bounce reflection data. The inversion approach has the potential to resolve fine-scale sediment profiles over small seafloor footprints (~100 m). The approach utilises sequential Bayesian inversion of time- and frequency-domain reflectivity data. employing ray-tracing inversion for reflection travel times and a layer-packet strip-ping method for spherical-wave reflection coefficient inversion. Rigorous uncertainty estimation is of key importance to yield high quality inversion results. Quantitative geoacoustic uncertainties are provided by a nonlinear Gibbs sampling approach to¬gether with full data error covariance estimation (including non-stationary effects). The small footprint of the measurement technique combined with the rigorous inversion of both time and frequency domain data provides a powerful new tool to examine seabed structure on finer scales than heretofore possible. The Bayesian inversion is applied to two data sets collected on the Malta Plateau and the Strait. of Sicily during the SCARAB98 experiment. The first application aims to recover multi-layered seabed structure and the second application recovers density and sound velocity gradient structure in the uppermost sediment layer. An interesting new method of deriving reflectivity data from ambient noise measurements is briefly considered in simulation to examine the resolving power and limits of the approach.

This thesis investigates shallow gas hazards in Queen Charlotte Basin, a sedimentary basin situated offshore British Columbia. The work presented here provides the first detailed gas hazard assessment in Queen Charlotte Basin and the first evidence that gas has migrated from basin sediments into surficial sediments to be expelled in the water column. A unique method of geophysical surveying is used to investigate hazards due to shallow gas at two sites within Queen Charlotte Basin: high-resolution multichannel seismic, Huntec Deep-Towed Seismic and multibeam bathymetry data were collected over two 2-D grids and interpreted concurrently to yield a comprehensive understanding of the geology at each site. Numerous features related to both ice-cover and shallow gas has been identified. Pockmarks, iceberg ploughmarks and seafloor mounds are observed in the multibeam data; acoustically turbid and vertical blank zones are imaged in the Huntec data and faulted anticlines containing bright spots as well as low frequency shadow zones are seen in the multichannel data. Combining and interpreting all three geophysical datasets concurrently provided the means to discriminate features related to ice-cover from features related to gas in the shallow sediments. In addition, this method of geohazards assessment has enabled links between surficial and basin geology to be made. Based on the results obtained gas and other geohazards were identified at each of the two sites. Based on observations in high-resolution multichannel seismic data, gas is determined to have migrated along structural pathways within basin sediments and into surficial sediments. The level of hazard posed by shallow gas has been assessed qualitatively for each of the two study sites and gas hazard regions have been identified elsewhere in Queen Charlotte Basin.

Moraine and glacier dams bordering the Homathko Icefield burst in the 1980s and 1990s, causing catastrophic downstream floods. The largest of the floods occurred in August 1997 and was caused by rapid breaching of the dam that impounds Queen Bess Lake, below Diadem Glacier. The outburst flood from the lake eroded the Holocene-age sediment fill in the valley below, exposing a series of subfossil forest layers separated by overbank floodplain sediments. A field investigation of the eroded valley fill in 2008 revealed multiple paraglacial valley-fill units, many of which are capped by in situ stumps and woody detritus. Dendrogeomorphic dating and stratigraphic evidence revealed six major sediment deposition events that coincide with regional, independently dated glacier episodes over the past 1200 years. Construction of tree-ring chronologies for the study area also allowed for the examination of the relationship between radial tree growth and hydroclimate. Dendroclimatological and dendrohydrological techniques were used to reconstruct summer stream discharge of nearby Chilko River. An Engelmann spruce tree-ring chronology provided a proxy for mean summer discharge of Chilko River for the period 1775-2007. This record is the first to be developed from tree-ring data for a river draining a glacierized watershed in the British Columbia Coast Mountains. This proxy record provides insights into streamflow variability of a typical Coast Mountains river over the past 232 years and confirms the long-term influence of the Pacific Decadal Oscillation and El Niño-Southern Oscillation teleconnections on hydroclimatic regimes in the region.

Recent advances in otolith microchemistry have established that trace element composition can be used to chemically reconstruct fish life history and serve as a stock identification tool. In modern fisheries practices, these two applications are especially pertinent to wild salmon populations, which are difficult to track over large spatial scales and nearly impossible to identify in mixed populations. This project has applied a novel method using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to anadromous sockeye salmon (Oncorhynchus nerka) otoliths from four separate watersheds in Sitka, Alaska. Spatial distributions of Li, Mg, Mn, Zn, Sr, and Ba were determined via continuous lateral ablation scans across the diameter of transversely sectioned sagittal otoliths. Time-series data generated from line scan analysis were used to chemically reconstruct sockeye life history, and examine elemental signatures in the core, freshwater, and marine growth regions of otoliths for stock identification purposes. Chemical profiles of life history showed that Sr, Ba, and to a lesser degree Mg, reflected ambient chemistry, and were effective for tracking sockeye migration from fresh to marine water. Manganese was also effective for determining migration to fresh and marine water; however, it is believed that diet more than ambient chemistry is the factor controlling uptake. Elements such as Zn and Li provided information related to fish physiology, such as growth and changes in osmoregulation during transitions from low to high salinity environments. Results also showed that several elements were either enriched or depleted in the core of sockeye otoliths. Maternal investments and spatial differences in crystal structure are believed to significantly affect element uptake in otoliths during incubation and early development. Elemental signatures in the otolith core may therefore be inaccurate as an indicator of stock origin. This problem was investigated by isolating core, freshwater, and marine signatures and evaluating individually their ability to correctly classify sockeye otoliths to their natal watersheds using step-wise discriminant function analysis. This demonstrated that freshwater signatures provided the greatest accuracy (91%) for stock ID. Core signatures, which have been used in past stock ID studies, showed poor classification results (68%) for sockeye salmon otoliths. Trace element signatures from the marine growth regions of sockeye otoliths displayed the poorest classification accuracy (52.5%) of the three growth regions. Thus, freshwater signatures are the most effective tool for identifying the origin of wild salmon, even when they far removed from their natal watersheds.

MERIS data and Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) ecosystem model coupled with the Princeton Ocean Model (POM), were used to investigate seasonal variations in surface chlorophyll distributions and their controlling factors to clarify phytoplankton dynamics in the upper Gulf of Thailand. Chlorophyll maps were produced by application on MERIS Level 2 data an empirical algorithm derived from the regression analysis of the relationship between chlorophyll-a concentration and remote sensing reflectance ratio. The results indicated that the patterns of seasonal chlorophyll distributions corresponded to local wind and water circulations. The model simulation highlighted the importance of river water as a significant nutrient source, and its movement after discharge into the sea is controlled by seasonal circulations. High chlorophyll concentration located along the western coast following the direction of counter-clockwise circulation, forced by the northeast winds, while chlorophyll accumulation was observed in the northeastern corner of the gulf due to clockwise circulation, driven by the southwest winds. These key simulated results are consistent with those of field observations and satellite images captured in the same periods of time, and also described seasonal shifting of blooming areas previously reported. Sensitivity analysis of simulated chlorophyll distributions suggested that not only nutrients but also wind-induced vertical movement plays a significant role in controlling phytoplankton growth. Plankton blooms occur in zones of upwelling or where vertical diffusivities are low. Increasing nutrients in the water column due to river loads leads to increasing potential for severe plankton blooms when other photosynthetic factors, such as water stability and light, are optimized. The knowledge of seasonal patterns of blooming can be used to construct environmental risk maps which are very useful for planning to mitigate the eutrophic problems. Effective measures need to be applied to control amount of nutrients released into natural water in order to minimize severity of red tides.

Co-located measurements of acoustic backscatter and temperature/velocity microstructure are used to confirm theoretical predictions of sound scatter from oceanic turbulence. The data were collected with a torpedo-shaped vehicle carrying four shear probes and two thermistors on its nose, and forward-looking 44.7 and 307 kilohertz echosounders (mounted 20 centimetres below the turbulence sensors). The vehicle was towed through the stratified turbulence that forms tidally over the lee side of a sill in a British Columbia fjord. Conventional downward-looking echosounder measurements were also made with a 100 kilohertz sounder mounted in the ship’s hull. Populations of amphipods, euphausiids, copepods and gastropods were present in the fjord (sampled with 335-micrometre mesh vertical net-hauls) and could be seen in the sounder data. These plankton net-hauls indicated that there were too few zooplankton in the turbulent regions to account for the scattering intensity. At both 44.7 and 307 kilohertz, scatter that is unambiguously correlated with turbulence was observed. Turbulent scatter is much stronger at the higher frequency, illustrating the mportance of salinity microstructure—long neglected in turbulent scattering models—and shedding some light on the form of the turbulent temperature-salinity co-spectrum. The turbulent temperature-salinity co-spectrum has never been measured directly. Although several models have been proposed for the form of the co-spectrum, they all produce unsatisfactory results when applied to the turbulent scattering equations (either predicting negative scattering cross-sections in some density regimes or predicting implausible levels of correlation between temperature and salinity at some scales). A new co-spectrum model is proposed and shown to be not only physically plausible in all density regimes, but also in reasonable agreement with the scattering data. At 307 kilohertz, the backscatter is mostly from salinity microstructure and, depending on the strength of the stratification, can be as strong as—or stronger than—the signal from a zooplankton scattering layer. This could easily confound zooplankton biomass estimates in turbulent regions. The two targets’ different natures (discrete targets versus a volume effect) often allow them to be distinguished even when they occur simultaneously. The key is sampling the same targets at multiple ranges. At long-range, discrete targets have a constant volume scattering strength proportional to their number density. The sampling volume, however, decreases as the targets approach the sounder. At some range there will be only one (or no) target in the sampling volume and the volume scattering strength will increase (or disappear) as the target continues to near the sounder. Turbulence, as a volume scattering effect, has no range dependence to its volume scattering strength. Thus, by examining the scattering nature at close range we can distinguish discrete targets (like zooplankton) from turbulence.