In this study, vertical profiles of velocity and hydrographic properties measured by the Lowered ADCP and CTD, respectively are used to calculate the vertical eddy diffusivity K based on small-scale turbulence theory. Two methods are used to estimate K, that is, the Thorpe scale analysis method (designated as Kz) and vertical wave number shear spectral method (designated as Ksh). Four different experiments with different flow conditions and bathymetry, i.e., internal tides, deep open-ocean, nonlinear internal waves and Kuroshio, are conducted and their K values are estimated and discussed. The internal tides at the mouth of Kao-Ping Submarine Canyon (KPSC) are observed during July and December (spring tide) of 2008. In each cruise the LADCP/CTD casts are repeated every two hours and last 27 and 40 hours, respectively. The results indicate the existence of strong, semi-diurnal internal tides with vertical displacement of 50~100 m and the nature of first baroclinic mode. Turbulent mixing during flood is significantly stronger than that during ebb. Note that in the winter experiments the Kz can reach 0.01 m2 s-1, which is even larger than the reported Kz values in other submarine canyons of the world, suggesting strong mixing processes are taking place in the KPSC. From the LADCP/CTD data of the joint hydrographic survey on May 2008 at SEATS station of the South China Sea, the estimated average values of Kz and Ksh in the upper 3000 m are about 3¡Ñ10-4 m2 s-1 and 1.8¡Ñ10-4 m2 s-1, respectively. The average value of Kz near the ocean bottom increases to 2.5¡Ñ10-3 m2 s-1. These estimated Kz are somewhat larger than the reported values in the open ocean. On the other hand, Kz values between 300 and 700 m deep are almost zero, indicating that turbulent mixing is inhibited in the stratified layer. Nonlinear internal waves are tracked in the South China Sea during May 2007. Our results show that after the internal solitons passed in the deep waters, the Kz profiles change significantly, surface mixing is weak, and Kz increases gradually from 400 m deep to the ocean bottom. In the shallow water region, shoaling effect of the nonlinear internal waves lead to enhanced energy dissipation and higher values of Kz, with the maximum value reaches 1 m2 s-1 near 180m depth. The flow structure of Kuroshio current between Taiwan and Lanyu is observed in October 2007. The results show that Kz in the surface layer is high (~10-2 m2 s-1), obviously due to strong Kuroshio flows there. At the 3000 m deep submarine trench near Lanyu, the Kz in the bottom layer is also very high (~ 1 m2 s-1 ), indicating that effective turbulent mixing in the bottom layer is mainly due to topography, which has similar level as the nonlinear internal waves.

This research investigated the accumulation of metals (Cu, Zn, Cr, Pb, Cd and Fe) in sediment of Gao-ping River and Gao-ping submarine canyon. Both Sediment Quality Guidelines (SQGs) by National Oceanic and Atmospheric Administration (NOAA) and Soil Quality Guidelines by Taiwan Environmental Protection Agency (EPA) were used to assess the extent of risk of these metals to the local ecological system. The results found no significant correlation between concentration of metals and volatile solid as well as particle size. It is noted that significant contaminations in zinc and lead were observed in sediments from both Gao-ping River and the starting point of Gao-ping submarine canyon, which concentrations exceeded the guidelines of Effect Range-Medium (ERM) by NOAA. Very likely, this is resulted from the metal and electroplating factories in the catchment area of Gao-ping River. It also provides evidence of the role of Gao-ping submarine canyon in accumulation of terrestrial and anthropogenic pollutants.

The purpose of this research is to understand the sinking particle dynamics in the Gaoping Submarine Canyon (GPSC), the change of their geochemical character, and their causal relationship with dynamic parameters. Also this research inquires into the significance of sedimentary environment, transport process, and the influence of non-tidal actions (turbidity current) in the sedimentary environment. The field experiments including LADCP moorings, T6KP(1/10/-3/20), and T7KP (7/7-9/11) sediment traps moorings were deployed in the GPSC to collect the time-series data of sinking particle and related dynamic parameters. Parameters of discrete sediment analysis were used to build continuous time-series data by interpolation, and time series analysis applied to understand the change of physical and geochemical character and their correlation with dynamic parameters. The results showed that sinking particles of different grain-size classes confront different forces in the canyon and their grain-size distribution structures are influenced accordingly. Vertical component of the flow has more influences on coarse particles, while the along canyon flow component has more influences on fine particles. The influence of semidiurnal tide on sinking particle is not clearly resoloved, but spring tide and neap tide affect them significantly. GPSC is normally a stable deposition environment dominated by tidal currents. Particle-reactive materials vary upon with clay concentration, coarse paericles vary upon with the flow field, and the change of benthic nepheloid layer thickness during spring and neap tide cycle affects the vertical distribution of particle size-groups near the bottom of canyon. The particle in the upper (rim) and lower (near the bottom) canyon belong to different transport and dynamic regimes. The upper part was affected by upwelling and shelf processes, while the lower part was affected by tidal currents. In case of episodic event, if surge-like turbidity flows pass near the canyon floor, in the waxing phase, the sinking particle would be affected by the strong momentum of resuspension and mixing which leads to a dramatic change of geochemical character of these particles. In turbidity current event, coarse sand and silt are the major particle sizes with low clay content, suspended sediment concentration about 4.41 g / l. The fluctuation of time series analysis by HHT found a frequency between 2.1~9.8 clcle per day. In the waning phase, dynamics and geochemical character of sinking particle will gradually return to those variations in tidal dominance. In winter, most sinking particles in GPSC are the source material (particles of biological origin) coming from the off-sea with the upcanyon flow during spring tide period. In summer, most sinking particles in GPSC are the terrigenous material (higher organic matter) output from the Gaoping River during typhoons, and flowing to the South China Sea along the canyon with turbidity flow.

In order to better understand the flow dynamics of the Kaoping Submarine Canyon (KSC), this study conducted a series of field experiments to monitor the current, temperature, salinity and tide near the KSC by using shipboard ADCP, CTD and moorings of RCM-8 and workhorse ADCP. Three cruises of Sb-ADCP and CTD have been carried out in September and December of 1999 and May 2000, each lasting two days, while mooring experiment was conducted in June and July, 2000. Least-square fit was applied to the time series Sb-ADCP data of each grid to derive the amplitude and phase of M2 tidal current and the residual flow in the KSC. Our results revealed that a string baroclinic flow field was present in the KSC. Tidal ellipse of the bottom current is dominated by M2 component, with higher M2 percentage in deeper layers. The major axis of the tidal ellipse is parallel to the direction of the canyon axis. In floods, the bottom layer flows down-canyon and the surface layer flows southeastward along the coastline. In ebbs, the situation is reversed. Variations of the temperature and salinity in the bottom layer also exhibit periodic oscillation of the M2 frequency. Daily temperature fluctuation in summer can reach 8 oC, indicating the existence of internal tide in the KSC. The surface residual current flows toward the south east in September and May, with a maximum speed of approximately 30 and 50 cm/s, respectively; the result is probably due to the bifurcation of the summer monsoon flows by the southwestern coastline of Taiwan. In December the surface residual current is northwestward, the maximum speed can reach 80 cm/s. Such a northward mean flow is probably originated from branching of the Kuroshio through Bashi Channel in the winter monsoon season. To summarize, mechanisms for the upwelling event in the KSC consist of surface flow direction, tidal range, and the stratification. The upwelling event occurs more often in the KSC between May and September with the surface mean current flows southeastward or left-bounded. In December when the surface mean current flows northwestward or right-bounded, the upwelling event is rare. An eddy structure of 7 ~ 9 km length scale was observed north of Liu-Chiu Yu, a result possibly produced by Karman vortex street for strong geophysical flows behind an island.

In order to better understand the flow dynamics of the Kaoping Submarine Canyon (KSC), this study conducted a series of field experiments to monitor the current, temperature, salinity and tide near the KSC by using shipboard ADCP, CTD and moorings of RCM-8 and workhorse ADCP. Three cruises of Sb-ADCP and CTD have been carried out in September and December of 1999 and May 2000, each lasting two days, while mooring experiment was conducted in June and July, 2000. Least-square fit was applied to the time series Sb-ADCP data of each grid to derive the amplitude and phase of M2 tidal current and the residual flow in the KSC. Our results revealed that a string baroclinic flow field was present in the KSC. Tidal ellipse of the bottom current is dominated by M2 component, with higher M2 percentage in deeper layers. The major axis of the tidal ellipse is parallel to the direction of the canyon axis. In floods, the bottom layer flows down-canyon and the surface layer flows southeastward along the coastline. In ebbs, the situation is reversed. Variations of the temperature and salinity in the bottom layer also exhibit periodic oscillation of the M2 frequency. Daily temperature fluctuation in summer can reach 8 oC, indicating the existence of internal tide in the KSC. The surface residual current flows toward the south east in September and May, with a maximum speed of approximately 30 and 50 cm/s, respectively; the result is probably due to the bifurcation of the summer monsoon flows by the southwestern coastline of Taiwan. In December the surface residual current is northwestward, the maximum speed can reach 80 cm/s. Such a northward mean flow is probably originated from branching of the Kuroshio through Bashi Channel in the winter monsoon season. To summarize, mechanisms for the upwelling event in the KSC consist of surface flow direction, tidal range, and the stratification. The upwelling event occurs more often in the KSC between May and September with the surface mean current flows southeastward or left-bounded. In December when the surface mean current flows northwestward or right-bounded, the upwelling event is rare. An eddy structure of 7 ~ 9 km length scale was observed north of Liu-Chiu Yu, a result possibly produced by Karman vortex street for strong geophysical flows behind an island.

Abstract The carbon and oxygen isotopes of planktonic foraminifera, faunal assemblage, and coarse fraction of trap materials were analyzed in this study. The sediment traps were deployed in two lacations. One was in the Kao-ping submarine canyon and the other was in the northern South China Sea. Variations of the individual concentrations from Kao-ping submarine canyon are small throughout the deployment interval except for the period when the Typhoon Chi-Te invaded southern Taiwan in July 2000. The results that benthic foraminifer abundances (#/g) are higher than that of planktonic foraminifera after typhoon invasion reflect the influence of particle settling by lateral transport. In addition, the major planktonic foraminifera found in canyon are Globigerinoides aequilateralis, Globigerinoides ruber, Globigerinoides sacculifer, and Neogloboquadrina dutertrei. At the same time, we also found Globigerina bulloides that usually lives in the high latitudes and cold temperature. It reveals the effect of nutrient supply along coastal region. The coarse fraction contents and foraminiferal abundances collected by the traps in the northern South China Sea are both increasing in January and March. It could be associated with the enhanced surface productivity. The planktonic foraminifera divided into two groups based on their preferrence. The G. bulloides and N. dutertrei live in cold environment while G. aequilateralis, G. ruber, G. sacculifer, and Pulleniatina obliquiloculata preferr warm areas. In this study, G. bulloides and N. dutertrei were found in January whereas G. aequilateralis, G. rubber, G. sacculifer, and P. obliquiloculata were mostly in March. The difference of carbon isotopes of planktonic foraminifera between species are distinct. Orbulina universa is the heaviest and G. ruber was the lightest. Foraminiferal d18O are depleted in October and enriched in January and March. It is suggested that sea surface temperature might be responsible for the variations of planktonic foraminiferal oxygen isotopes. Comparisons of foraminiferal d18O with the hydrographic data provide some informations. The results show that G. ruber lives in shallow water (~10m), G. sacculifer lives in 25m on average, and O. universa lives in deeper water layer (~70m) in northern South China Sea. Moreover, both the carbon isotopes and foraminiferal abundance of G. ruber show a negative correlation with the particles fluxes.

The internal tide in GPSC¡]Gaoping submarine canyon¡^is the main factor controlling the movement of watermasses. In order to improve our understanding on the compact of suspended sediment exchange in and out GPSC, the data used in this study are collected from four cruises of field observations using research vessel OR3. Instruments deployed include ADCPs¡BEK500¡BCTD and vertical string of temperature loggers. The collected data are analyzed through a variety of time series analysis technique, such as harmonic analysis¡BFFT and EOF. The results show that¡]1¡^the echo intensity recorded by ADCP through calibration could reduce the decay of echo with the distance. The results seem useful to apply in watermass behavior studies.¡]2¡^ Echo intensity with calibration were comparable with signal recorded by EK500 which could be validated to each other. These observations were related to sediment resuspension influenced by internal tide. ¡]3¡^There were two layers of large turbidity, at the depth of canyon edge and near the bottom of canyon, both were fluctuated with two interval tidal frequency.¡]4¡^Another band of echo intensity fluctuations, not directly correlate to sediment resuspension, was likely due to vertical migration, of zooplankton or biology effects.

The South Westland Continental Margin (SWCM) is incised by two major active canyon channels, the Hokitika and Cook canyons, which export large volumes of terrigenous sediment from the active New Zealand landmass to the deep ocean basins. This thesis examines modern sediment textures and compositions of shelf and canyon heads, to interpret depositional and transport processes in shelf-canyon interactions and the dispersal and provenance of SWCM surface sediments. This is the first detailed study of modern sediments south of the Whataroa River which focuses on both shelf and canyon head sediments. Submarine canyons that incise active continental shelves are major conduits for sediment transfer. The frequency and magnitude of this transfer has important implications for ocean nutrient cycling (i.e. organic carbon), the stratigraphy and morphology of continental shelves, and the development of economic mineral deposits. Grain size analysis, petrology, geochemistry, detrital magnetite analysis (microprobe), swath bathymetry, and wave hindcast data are used to interpret the spatial distribution, dispersal, and provenance of surface grab samples, canyon cores, and beach and river samples on the SWCM. Four main surficial facies are defined from textural and compositional results, primarily reflecting the supply and storm dominated nature of the SWCM. Facies 1 is comprised of inner shelf very fine to medium sand sized quartz, metamorphic lithics, and feldspar. This facies occurs above the mean Hsig wave base (48 m) where silts, clays, and sand sized micas are bypassed further offshore. Facies 2 is a transitional sand to mud facies between 40 -70 m depth where increasing clay, silt, and mica reflect a decrease in the frequency and magnitude of wave orbital remobilisation. Facies 3 is a mud dominated (80-90%), clay rich (7-9%) facies with the highest mica and Al₂O₃ content of all the SWCM facies. The shelves south of the Hokitika canyon are blanketed beyond the inner shelf in facies 3 towards the shelf break. Facies 4 is restricted to the canyon head north rims and is characterised by mixed relict and modern terrigenous sediments and glaucony. Net transport on the SWCM shelf is to the north, particularly during south-westerly storms where wind drift and storm swells may stir and transport the deeper Facies 2 and 3 sediments. The SWCM has an energetic wave climate and numerous high yield mountainous rivers. As a result the shelf has an extensive coverage of silts and clays with sediment transport most likely dominated by nepheloid layers and fluid mud flows during wet storms. North of the Hokitika canyon, shelf width increases as fluvial supply falls, resulting in a more storm dominated shelf as the prevailing hydraulic conditions prevent modern silts and clays from blanketing the outer shelf. Narrower shelf widths and higher fluvial supply between the Hokitika canyon and the Haast region results in more fluvial dominated shelves. Contrasting canyon rim textures and compositions reflect the major influence the Hokitika and Cook canyon heads impose on the SWCM by intercepting modern net northward shelf transport paths. This interception creates a leeward sediment deficit on the canyon north rims where low sedimentation rates prevail and relict sediments are partially exposed. The south and east rims of both canyons are characterised by modern fine grained terrigenous textures and compositions similar to the SWCM middle to outer shelf facies 3. The build-up and storage of these unconsolidated sediments at the south and east rims provides favourable environments for sediment gravity flows that feed into the canyon systems. Wave orbitals can resuspend fine sands up to 50 m below the canyon rims during large storms. This resuspension will be a main driver of canyon head sedimentation in the form of fluid mud flows. Gully networks along the south and east rims of the Hokitika and Cook canyons indicate active submarine erosion, unconfined fluid flow, and sediment gravity flows operate here. ii In contrast, the north canyon rims are characterised by gravels and coarse sands out of equilibrium with the prevailing modern hydraulic regime. Relict gravels are particularly prevalent on the Hokitika canyon north rim between 90 – 150 m depth. A lack of active gully networks and the presence of relict terraces and cuspate channels provide further evidence for a relict origin of HCH north rim sediments and little influx of modern fine sediments. North rim sediments on the Hokitika canyon between 90 – 125 m have features characteristic of relict beach and littoral environments. These features include pebble and coarse sand sized siliciclastics, high heavy mineral percentages (i.e. garnet), high Zr and Y levels, elevated SiO₂/Al₂O₃ ratios, and relict shell fragments. Mature glaucony is common on the north rims of both canyons, especially between 180 -200 m depth providing further evidence for extended periods of little to no modern sediment deposition in the canyon lee. Glaucony grains have experienced limited transport and are probably parautochthonous. The bulk composition of SWCM shelf, canyon, river, and beach sediments is controlled mainly by the hydrodynamic sorting of Alpine Schist derived material. Regional changes in catchment geology are identified in modern SWCM shelf sediments. Ultramafic signals (i.e. enriched trace element patterns and Cr/V and Ni/Y ratios) from the Pounamu Ultramafics and Dun Mountain Ultramafics were identified on the North and Cascade shelves respectively. The contribution of other lithologies to the bulk composition of SWCM sediments is localised due to rapid dilution with Alpine Schist detritus. The low carbonate and skeletal content on the SWCM is due to the energetic wave climate and high fluvial supply on the shelves. A variety of Cr-rich spinels and magnetites are supplied to the SWCM shelves and vary with regional changes in catchment geology. The Cascade shelf is rich in chromites (containing up to 215,000 ppm Cr) and Cr – rich magnetites sourced from the Dun Mountain Ultramafics via the Cascade River. Shelf, beach, and river samples between the Haast River and Waitaha River are dominated by low-Cr magnetite grains which represent the ‘background’ magnetite composition sourced from rivers draining the Alpine Schist dominated catchments. The dispersal of Cr-rich spinels is limited due to the dilution with low Cr-magnetites from rivers and littoral sediments. Glacio-eustatic lowstands such as the Last Glacial Cold Period (LGCP), represented periods of robust connection of local rivers with the Hokitika and Cook canyon heads, increased interception of littoral transport paths, and compartmentalisation of inter-canyon shelves. Hokitika canyon cores reflect these changes with textural and compositional ‘spikes’ indicating higher terrigenous input during the LGCP. The geochemistry of the terrigenous fraction in the Hokitika canyon provides evidence for enrichment in ferromagnesian and Cr-rich minerals during the LGCP. This is due to the increased connectivity of the Cr-spinel bearing Hokitika River to the canyon head. The Cr/V ratio in particular demonstrates its effectiveness as a proxy for interglacial – glacial change in submarine canyon stratigraphy. Increases and decreases in the connectivity of Cr-bearing fluvial systems during lowstands and highstands respectively can be observed with this ratio.

The Kaikoura area is a valuable feeding spot for sperm whales with the presence of a submarine canyon close to shore. Male sperm whales can be found there year around, close to the shore and exhibiting almost constant foraging activities. This thesis investigates the distribution and habitat use, both spatially and temporally, of sperm whales (Physeter macrocephalus) within the Kaikoura submarine canyon, New Zealand. The primary aim was to determine which oceanographic variables and bathymetric features influence the sperm whale distribution patterns off Kaikoura. A theodolite was used to track surfacing and movement of sperm whales from a shore-based station. The accuracy of positions recorded by the theodolite was investigated by comparing theodolite measurements of an object of known position. A calibration technique was then developed as the vertical angle was not accurately determined by the theodolite. In addition to investigating the distribution of sperm whales, the daily abundance of sperm whales within the Kaikoura submarine canyon was estimated. Distance sampling and mark-resight models showed an average of 4 (SEM = 0.13) individuals present in the study area at any given time. The mark-resight technique using photo-identification was not possible from a shore-based station so a spatio-temporal model was built in order to track the identity of individuals. The model was tested using photo-identification of sperm whales collected from a boat-based station. Results showed that 88% of the modeled identifications corresponded to the photo-identification database. Sperm whales off Kaikoura were strongly associated with depth, slope and distance from the nearest coast. They were found in waters between 500 m to 1250 m deep and preferred shallower waters in winter. In spring, sperm whales occurred further from the coast, mainly in the Hikurangi Trough, north-east of the shore-based station. Generalized Additive Models (GAM) were used to identify significant oceanographic variables predicting the presence of sperm whales off Kaikoura. Models indicated that sea surface temperature (SST), chlorophylla (Chla) and distance from sea surface temperature fronts were all important parameters in predicting sperm whales presence. Results showed that sperm whales aggregated in the section of the study area with the lowest SST and near SST fronts. This study provides a detailed insight into the use of the Kaikoura submarine canyon by male sperm whales.

Thesis (M.S.)--San Diego State University, 1991. / Includes bibliographical references (leaves 124-133).