It is well known that gases are present in marine sediments. The gas found in the surficial layer of marine sediments is mostly due to biological origin or migration from deposits in deeper layers. A nonlinear acoustic remote sensing technique based on the nonlinear acoustic scattering theory of gas bubbles is introduced in this thesis to identify the gas bubbles in surficial layers of marine sediments and measure their concentrations. Two close transmitting frequencies were used to generate a nonlinear scattering effect from the gas bubbles in the sediments, and the nonlinear responses were generated only by gas bubbles instead of by other scatters in the sediments. An acoustic inversion was implemented on the nonlinear response, together with calibration results and scattering volume, to determine gas bubble concentrations. Results from the data collected at Gulf of Gdansk demonstrate that the nonlinear acoustic method is advantageous over other acoustic remote sensing methods in gas bubble identification and measurement, and provides more valuable information for seabed classification.

Five profiles of the silver concentration in the subArctic Northeast Pacific Ocean yield a broad correlation between the Ag content and dissolved Si. However, silver is depleted at intermediate depths where the 02 content is low, implying removal from oxygen-deplete waters. An eighteen-month series of measurements of dissolved and particulate Ag from Saanich Inlet, BC indicate that Ag concentrations in near-surface waters are influenced by processes occurring outside the inlet. Dissolved silver was not detected in sulphide-bearing deep waters in the fjord. Ag in sediment-trap particles was associated with both biogenic and mineral phases. The Ag/biogenic Si ratio of the particles is related to the concentration of dissolved Ag in the surface waters suggesting a direct link between availability of the metal and its sequestration by diatoms.

This thesis presents a methodology for modelling underwater sound propagation from seismic airgun surveys. Subsequently, the method is applied to the case of predicting noise levels from offshore oil and gas exploration in the Queen Charlotte Basin region of the British Columbia offshore. Underwater noise levels are predicted using an integrated mod¬elling approach that incorporates (i) an airgun array source model. (ii) a broadband 3-D transmission loss model, and (iii) environmental databases of high resolution bathymetry. historical CTD casts and geoacoustic properties of the seabed. As part of this thesis, an airgun array source signature model is developed and then used for predicting the acoustic source level of a seismic airgun array. The airgun model, based on the physics of the oscillation and radiation of airgun bubbles, is validated against real airgun data. Under-water sound propagation is modelled in three dimensions using a parabolic-equation (PE) based, "Nx2-D" transmission loss model. Broadband sound propagation is approximated by modelling acoustic transmission loss at third-octave band centre frequencies; noise levels are computed by subtracting transmission loss from the respective third-octave band airgun array source levels. High resolution bathymetry and geoacoustic data for Queen Charlotte Basin are extracted along centrolineal radial transects for input to the propagation model. Additionally, principal component analysis is applied to a large collection of historical CTD data to extract seasonal sound speed profile variations. Transmission loss is modelled using both winter and summer sound speed profiles to bracket seasonal variations in acoustic propagation conditions. Noise level estimates from the acoustic modelling may be used to determine impact zones around the survey vessel where marine mammals are expected to exhibit disturbance reactions to airgun noise. Results from this study will aid in evaluating the potential environmental impacts of seismic exploration activity on marine ecosystems in British Columbia's offshore region.

The overall goal of this thesis is to develop non-linear Bayesian methods for three-dimensional tracking of a moving acoustic source in shallow water despite environmental uncertainty, with application to data from a horizontal line array (HLA) of hydrophones. As a precursor, Bayesian geoacoustic inversion is applied to estimate seabed model parameters and their uncertainties. A simulation study examines the effect of source and array factors on geoacoustic information content in matched-field inversion of HLA data, as quantified in terms of model parameter uncertainties. Bayesian geoacoustic inversion is applied to both controlled-source and ship-noise data from a HLA deployed on the seafloor in a shallow-water experiment conducted in the Barents Sea. A new approach is introduced to account for data error reduction due to averaging data over time-series subsegments (snapshots), based on empirically apportioning measurement and theory error, with effects on inversion results compared to those of existing approaches. It is further demonstrated that combining data from multiple, independent time-series segments (for a moving source) in the inversion can significantly reduce geoacoustic parameter uncertainties. Geoacoustic uncertainties are also shown to depend on ship range and orientation, with lowest uncertainties for short ranges and for the ship stern/propeller oriented toward the array. Sediment sound-speed profile and density estimates from controlled-source and ship-noise data inversions are found to be in good agreement with values from geophysical measurements. Two non-linear Bayesian matched-field inversion approaches are developed for three-dimensional source tracking despite environmental uncertainty. Focalization-tracking maximizes the posterior probability density (PPD) over track and environmental parameters. Synthetic test cases show that the algorithm substantially outperforms tracking with poor environmental estimates and generally obtains results close to those achieved with exact environmental knowledge. Marginalization-tracking integrates the PPD over environmental parameters to obtain joint marginal distributions over source coordinates, from which track uncertainty estimates and the most probable track are extracted. Both approaches are applied to data from the Barents Sea experiment. Focalization-tracking successfully estimates the tracks of the towed source and a surface ship in cases where simpler tracking algorithms fail. Marginalization-tracking generally outperforms focalization-tracking and gives uncertainty estimates that encompass the true tracks.

The concepts and issues surrounding the study of sacred places represent a complex interaction of mindscapes and landscapes. Using as the main examples Stonehenge and the Bighorn Medicine Wheel, this thesis is about these interactions in natural, community sacred places and serves two main purposes. The first is to clarify the meaning of -sacred- and the application of sacred designation to natural places. The second is to explore options for the protection. conservation and restoration of such places. In addition. an interpretation of cultural issues surrounding the understanding of the sacred in place explores and explains the connections between worldviews, stories or mythologies, and sense of place in sacred places so that a better understanding can be reached of the paradigms that underlie our conception of the sacred and of nature. and by extension, the sacred in nature. This in turn serves to illuminate the recommendation of focal restoration techniques to restore sacred places.

A quasi-two dimensional model for the southern Vancouver Island shelf was developed with the Regional Ocean Modelling System (ROMS) to study coupling of the carbon, oxygen, and nitrogen cycles in a summer wind-driven upwelling region. The physical model is coupled to an ecosystem module that includes a simple representation of a sediment layer and considers non-fixed C:N ratios for detritus and dissolved organic matter (i.e., explicitly modelled pools of carbon and nitrogen for those variables). The model accounts for denitrification within the sediments as well as within the water column when oxygen concentrations are low (below 5 mmol-O2 m-3). The objective is to identify the dominant processes controlling the cycles, their coupling, and their sensitivity to changes in environmental forcing. Results demonstrate how low oxygen and low pH events are tightly coupled in the coastal study region, especially through local ecosystem processes. In particular, exchange with the sediments plays a dominant role in consuming oxygen from and releasing inorganic carbon to the bottom waters on the shelf. Two key features distinguish the southern Vancouver Island shelf from other coastal regions in the California Current System and protect inner shelf waters from severe hypoxia and corrosive (i.e., undersaturated in aragonite) conditions. First, the greater width of the shelf reduces the penetration of subsurface offshore high-carbon and low-oxygen waters into shallower waters; and second, the relatively fresh Vancouver Island Coastal Current (VICC) brings oxygen-rich and carbon-poor waters to the bottom layer over the inner shelf. Sensitivity experiments show that carbon and oxygen cycles on the southern Vancouver Island shelf may be significantly affected by an altered upwelling season, a shallower offshore Oxygen Minimum Zone, a warmer ocean, and a carbon-enriched environment. Combinations of these scenarios suggest a potential increasing risk for the development of coastal hypoxia and corrosive conditions in the future. Further sensitivity simulations indicate that sedimentary denitrification provides an additional coupling between the carbon, oxygen, and nitrogen cycles. Total alkalinity generated by sediment denitrification has the potential to buffer anthropogenic ocean acidification. However, this alkalinity effect over the Vancouver Island shelf in late spring and summer simulations is small compared with studies for other locations at annual scales. Longer time scales need to be examined in this region to confirm whether the role of alkalinity generation in the sediments is significant. In conclusion, this dissertation not only demonstrates the coupled nature of biogeochemical cycles in the coastal ocean, but also the importance of this coupling as we try to estimate how coastal ecosystems will respond to human modifications of shelf waters and the climate.

The submarine geomorphology of Goletas Channel - Hardy Bay - Shusharti Bay is a record of environmental change, defined by sediment deposition since the late Pleistocene draped over glacially sculpted physiography. Sea level change, contiguous with waning ice extent at the termination of the Fraser Glaciation, triggered an oceanographic transition within Goletas Channel from a low energy closed embayment to a higher energy open channel environment. Morphologic evidence of lower sea level position is observed from sequence stratigraphy in Hardy Bay and suggests regression to 74 m below present. Stratigraphy also shows a correlation between sea level transgression and turbidity current flows in northwest Goletas Channel, and although triggering mechanisms remain elusive, they are likely related to reworking of glacial sediments concomitant to initial open channel conditions. Holocene sediment accumulation has been highest in southeast Goletas Channel, represented by mud with interstitial gas, and has been reworked by tidal currents into contourite structures. A combination of high-resolution multibeam bathymetry, seismic and core samples are used to study the geomorphology of the region.

A statistical downscaling technique is employed to link atmospheric circulation produced by climate models at the large-scale to precipitation recorded at individual weather stations on Vancouver Island. Relationships between the different spatial scales are established with synoptic typing, coupled with non-homogeneous Markov models to simulate precipitation intensity and occurrence in historical and future periods. Types are generated through a clustering algorithm which processes daily precipitation observations recorded by Environment Canada weather stations spanning 1971 to 2000. Large-scale atmospheric circulation data is taken from an ensemble of climate model projections made under the IPCC AR4 SRES A2 scenario through the end of the 21st century. Atmospheric predictors used to influence the Markov model are derived from two versions of the data: Averages of model grid cells selected by correlation maps of circulation and precipitation data; a new approach involving Common Empirical Orthogonal Functions (EOFs) calculated from model output over the Northeast Pacific Ocean. Circulation-based predictors capture the role of sea level pressure (SLP), and winds in influencing coastal precipitation over Vancouver Island. The magnitude and spatial distribution of the projected differences are dependent on the predictors used. Projections for 2081 to 2100 made using common EOFs result in most stations reporting no statistically significant change compared to the baseline period (1971 to 2000) in both seasons. Projections using averaged grid cells find winter season (Nov-Feb) precipitation anomalies produce values that are modestly positive, with typical gains of 6.5% in average precipitation, typical increases of 7.5% rising up to 15% in extreme precipitation, and little spatial dependence. In contrast, average and extreme summer precipitation intensity (Jun-Sep) declines negligibly at most island weather stations with the exception of those on the southern and western sections, which experience reductions of up to 20% relative to the latter thirty years of the twentieth century. Precipitation occurrence decreases slightly in both seasons at all stations with declines in the total days with measurable precipitation ranging from 2% to 8% with reductions also seen in the length of extended periods of precipitation in both seasons.

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.

The Tally Ho shear zone (THSZ) is a 40-kilometre long, northwest-striking assemblage of highly-deformed rocks outcropping along the western margin of Stikinia in southern Yukon. The location of the THSZ adjacent to the boundary between the oceanic Stikine Terrane and pericratonic Nisling Assemblage of the Yukon-Tanana Terrane provides an opportunity to examine the tectonic significance of a terrane-marginal high-strain structure. Detailed geological mapping along the THSZ and adjacent rocks indicates that the shear zone is a crustal-scale thrust fault that places deep-seated arc rocks of Stikinia up-section and to the east onto a package of upper crustal volcanic and volcaniclastic rocks of the Upper Triassic Lewes River Group. Timing of movement along the THSZ is constrained by U-Pb zircon age determinations of a deformed section of cumulate leucogabbro in the hangingwall of the shear zone (208 ± 4.3 Ma) and by a post-kinematic cross-cutting megacrystic granite intrusion (~173 Ma). Positive Nd values of Stikine magmatic rocks (+4.5 to +6.7) indicate magmas forming the oceanic terrane were formed with little to no input of continental crust until around the time of intrusion of a megacrystic granite unit in the mid-Jurassic (Nd -4.0). The THSZ is therefore interpreted to have formed in response to the thick-skinned collision and underpinning of the Nisling Assemblage beneath western Stikinia in the Early Jurassic resulting in the imbrication of the Stikine magmatic arc along the THSZ.