This study investigates the hydrodynamic variations along the Gao-ping Submarine Canyon influence by the topography effects. The data used in this study were collected from two cruises of field observations using research vessel OR3. Instruments applied include sb-ADCP¡Bbm-ADCP¡Bmoored-ADCP¡BCTD and several vertical strings of temperature loggers. Parameters recorded include flow velocities, water temperature and tidal elevation. The analysis method is enlightenment by the case study in the Monterey Canyon of California. The results show that (1) the current speed in the lower layer is faster than that of upper layer, which is explained due to v-shape of topography and bottom-trapped effect of internal tide. This result is consistent with previous studies. (2) In flood tide, the currents flowed into the Canyon from deep water to shallower. The baroclinic kinetic energy decreased to 0.2 at the turning point of canyon axis at 230m water, whichwas caused mainly by bottom friction. On the other hand, the baroclinic kinetic energy increased to 0.47 at 250m water in ebb tide when there was less influence of bottom friction. (3) In comparison the effects of bottom slope and area of cross section of the canyon, the baroclinic kinetic energy dissipation was mainly occurred at up slope flow during the flood tide. The change of the canyon width had less influence. During the ebb, the baroclinic kinetic energy was mainly due to the change of canyon width in the region shallower then the 230m of the second turning of the canyon. (4) The loss of kinetic energy during flooding up slope current can be verified by the changes of water mass temperature. Cold bottom was raised to upper layer when there was large drop of kinetic energy. There was likely a conversion of kinetic energy to potential energy. No upwelled cold water detected during ebb current with increase of kinetic energy.

Internal tide is generated in the interface of density stratification by some hydrodynamic disturbance. The major mechanisms are borotrophic tidal current oscillated at the edge of the continental shelf, submarine canyons, ridges or sills. The resulting disturbance generated has the same motion cycle of tidal period. There were internal tides reported in the Kaoping Submarine Canyon. The generation sites and mechanisms, however, are not clear. This study analysis four cruises of field observed data using ship mounted ADCP and CTD, and moored temperature strings and current meters. The results showed: (1) The phase of M2 tidal current increase toward the canyon head, with minimum value at the canyon mouth. This result implies that the internal tide was generated near the canyon mouth and propagated up canyon with the thermocline decreasing toward the shallower water. (2) The internal tide generated at the canyon mouth propagated, through some mechanisms, at the upper layer density interface about 150m instead of beaming near the bottom layer where the current and topography interact. (3) The vertical variations of tidal ellipse and phase based on bottom mounted ADCP support the results of ship mounted observations, the internal tidal energy propagates near the interface of 150m below the surface.

This study presents the first reconstruction of pollution history of Polychlorinated biphenyls (PCBs) in Taiwan coast. Six sediment cores were collected from Gaoping submarine canyon and its adjacent area to investigate the distribution and source recognition of PCBs. The concentrations of PCBs in the cores from Gaoping canyon ranged 0.155--2.281 ng/g dry wt, whereas the maximum concentrations of PCBs reached 21.0 and 2.93 ng/g dry wt, respectively, in the cores from the northern and sourthern continental shelf of Gaoping canyon. The toxicological effects assessed by sediment quality guidelines (SQGs), show that only 2-10cm in core L27 exceeded the guideline value suggested by Förstner (6 ng/g), which indicated the sediment in this area had been polluted seriously and should not be disturbed. Overall, compared with studies in the world, the sediment PCB concentrations in Kao-Ping coastal areas were relatively low. Hierarchical Cluster Analysis identified the source of PCBs in the study area was a mixture of Aroclor 1016, Aroclor 1242 and Aroclor 1260. Similarity in vertical variations of total concentrations of PCBs among the six cores was observed and the trend is consistent with the history of the PCB usage in Taiwan. The drastic decrease in PCB concentrations around the late 1980s, clearly demonstrates the effectiveness of the ban of PCBs use in 1980 in Taiwan.

Thesis (M.S.)--San Diego State University. / Includes bibliographical references (leaves [61]-65).

The objective for this study was to provide the insight into the link between benthic foraminiferal assemblages and the surrounding environment. Stained sediment samples were collected from the continental shelf and slope off the southwest Taiwan, including the Kao-ping Submarine Canyon. In addition to faunal census, total organic carbon (TOC), carbonate, and coarse fraction of the sediments were also measured. Nevertheless, the downcore record of the excess 210Pb from selected sites offers the constraint for stratigraphy time frame for discussion. The benthic foraminiferal assemblages were analyzed by statistics. Clusters analysis shows that all species present in this study could be divided into two groupings. One is those distributed in outer shelf and the other is those found in the inner shelf of the southwest Taiwan. Different from previous studies, the spatial distribution of stained benthic foraminifera seems not to be related with TOC contents in the sediment and water depth. Both the diversity index and Eqitability show that sites inside of the canyon have lower values. The higher Living/Total ratios and lower dead tests at the head of Kao-ping Submarine Canyon than adjacent area might be the effect of migration. Furthermore, the species within the canyon are similar to the southern and northern continental shelf. These findings indicate that the spatial distribution of benthic forams within canyon might be the effect of transport, which could result from the complex interaction between tides and currents. Augmented with the profiles of excess 210Pb, the temporal variation of benthic foraminifera was revealed. Generally there is a progressive decrease in the abundance of Ammonia sp.. It is possible that the diminishing trend was caused by the increase of anthropogenic activity for the last 30 years.

The interaction between the submarine canyon topography and coastal current has very important influence on the flow field around the canyon. This study aims to understand the nature of the interaction and the associated dynamic around the Kao-ping Submarine Canyon in southern Taiwan. In 2000 and 2002 year during the flood season of the Kao-ping River, moored instruments were deployed in the Kao-ping Submarine Canyon, Kao-ping River mouth, and Kao-ping shelf for one month. The results revealed sea surface fluctuations were dominated by the tide. The sea surface fluctuations at Kao-ping River mouth and Liu-Chiu Yu Island belong to mixed tide with diurnal dominance. But the sea surface fluctuations on the shelf belong to mixed tide is having by semi-diurnal dominance. The current fields of the shelf and canyon both are dominated by semi-diurnal tide. The energy of tidal current is stronger with increasing canyon depths. Results of harmonic analysis show that the current field of canyon bottom layer and on the shelf both is dominated by the M2 component. The variation of temperature field is regulated by tidal currents. During floods, shelf flow is northwestward and the current of canyon bottom layer flow downcanyon. During ebbs, shelf flow is southeastward and the current of canyon bottom layer flow upcanyon. The interaction between the temperature field of submarine canyon and shelf is pronounced. The tidal fluctuation of temperature field on shelf is especially conspicuous during spring tide. When temperature decreases in the submarine canyon, the shelf temperature begins to decline. When temperature increases in the submarine canyon, the shelf temperature begins to arise. The results of harmonic analysis reveal that the temperature field of the canyon leads that of the shelf around 2.08 hours. The current field of bottom layer in the canyon flows towards the canyon head during ebb tides. It brings the colder and deeper water to canyon head along the canyon axis. The colder and deeper water causes the water temperature to decrease in the canyon and on the shelf. During flood tides, the colder and deeper water withdraw from the canyon head region, which makes the shelf temperature increase. The currents on the Kao-ping shelf both are largely alongshore in 2000 and 2002 observations. The alongshore mean current is northwestward. The current velocity of surface layer is greater than that of the bottom layer. In Kao-ping Submarine Canyon, the mean current of bottom layer at 195m and 245m flows in opposite directions. It flows downcanyon offshore at 195m and upcanyon at 245m. The current velocity of 245m is greater than 195m. Mean current flow of bottom layer is downcanyon along canyon axis at 280m in 2002 year. During the transition between ebb tide and flood tide, temperature fields of canyon and shelf show trend reversal. Submarine canyons play an important role in transport deeper and colder water. The interaction of canyon and shelf current field can influence the variation of shelf temperature. The tidal current velocity is stronger in spring tide. It is easier to make deeper and colder water to ascend to the shelf. The influence of current is more noticeable to adjust on the shelf and canyon temperature fields during the spring tide. The results of scale analysis show the canyon topography can influence coastal current when the radius deformation of the canyon is smaller than the canyon width. The canyon current will produce phenomena of upwelling and down-welling with tidal periods. This seems match Klink¡¦s¡]1996¡^model results.

Kao-ping submarine canyon is straightly connected with Kao-ping River. Thus, it is influenced by the river¡¦s discharge. In order to investigate this seasonal difference in the canyon, we conducted several researches, which were based on temporal and spacial observations of the hydrological and dynamical characteristic of the canyon. We also studied the transport of suspended sediment particles in the canyon according to the distribution of SSC (suspended sediment concentration). In our research, we made along-canyon profile observations. We collected data by using CTD, ADCP and Transmissometer on R/V Ocean Researches Vessel ¢». The data include flood season cruises (CR536, CR248, CR552, CR634 and CR639), and dry season cruises (CR572, CR598, CR608). Based on the temporal and spacial observations, in June and July 1999 we found a cold pool at the location where canyon topography changed sharply. We also found the density disturbance and high concentration at the same location. When the tidal current was landward in the deep canyon, we can observes upwelling in the head region of the canyon. Conversely, we can observe downwelling while the tidal current was seaward. Moreover, we observed a strong vertical flow in the dry season, which can make resuspended easily. Besides, we deployed an instrument covey, including sediment traps, Recording Current Meter (RCM), wave gauge (S700) and Laser In-Suit Scattering and Transmissiometry (LISST-100), at the location where we previously observed SSC localizes high for one month (from June to July 2000) to investigate the temporal relations among temperature, salinity, flow, and suspended particles. From this time series observation we found a coincidence between cold temperature signal and the northward flow. It showed that the cold water from deep sea was transported to the head region of the canyon by a ¡¥Pump¡¦ process. We also observed the suspended particles at the top (195m), middle (245m), and the bottom (285m) of the ocean. According to their different sizes, we found that the upper depth has more sands which were from the continental shelf, and the middle and lower depth have more silt and clay. Subsequently, we used Empirical Orthogonal Function (EOF) analysis to explain the relationship among hydrological and flow factors of the canyon. We concluded that two major modes to explain the observed relationship: Submarine canyon seasonal effect, and dynamic stability.

Abstract The purposes of this study are to understand the variations of the particulate and dissolved 210Pb and 210Po profiles in the water column of Gaoping Submarine Canyon(GSC) and to compare the distributions of the two nuclides in settling particles and sediments. Different types of samples taken in this area were analyzed for 210Pb and 210Po in order to understand processes involved in the particulate transport. Seawater samples were collected from Ocean Researcher III Cruise (ORIII-1192 in Nov, 2006). Sediment trap was deployed on Jun 21, 2000 and recovered on Jul 20, 2000 (ORIII-634). Sediments cores collected from ORIII-642 on Jul 21, 2000 (Core A-B) and ORIII-696 on Apr 7, 2001 (Core D-F) using multicorer. The profiles of 210Pb and 210Po in water column could be divided into two types one is estuarine and the other is oceanic. The profiles of dissolved nuclides in estuarine stations (CW1 to 3) are lower than in the oceanic stations (CW4-5). Because stations CW1 to 3 are controlled by large amount of terrigenous particles, scavenging in the three stations is quite obvious. The nuclide activities of the settling particles decrease with depth, probably due to dilution by resuspended surface sediment of lower activities, similar to observations in this study area. The downcore distributions of 210Pb and 210Po show clearly disequilibria between the two nuclides and suggested that sediment deposited in GSC has been disturbed down to 40-50 cm deep. All the data indicate the 210Po in the water column and in the settling particles as well as in the surface sediments is strongly deficient relative to its parent, 210Pb. Using a box-model and considering the influence of horizontal transports, we may calculate the residence times of 210Po in the 100m water layer in the GSC, to be 2.1d for the dissolved phase and 7.0 d for the particulate phase with a total 210Pb residence time is 3.8d.

Submarine canyons are common features on continental margins worldwide. They are important natural conduits for transfer of terrigenous sediments to the deep sea, and thus, preferential pathways for shelf-slope exchange. The purpose of this study is to understand the biogenic particle transport in the seasons according two sediment trap moorings deployed in the Gaoping submarine canyon. The T6KP mooring was deployed in dry season while the T7KP mooring was deployed in wet season. Two typhoons, Kalmaegi and Fung Wong, invaded Taiwan during 16-18 and 26-29 July within the deployment of T7KP. We discussed the influence of rainfall and river discharge on biogenic particle transport based on results of the two sediment traps. The foraminiferal abundance in sediment traps in comparison with plankton tows was discussed regarding the particle transport mechanism of the water column in the Gaoping submarine canyon. The biogenic particle transport was a tide-dominated situation and displayed a periodic variation in dry season. In wet season, fine grain fraction (less than 63 micro meter) was dominant in the particle size and sedimentary condition was flood-dominated. The sedimentary condition was back to the tide-dominated state approximately 15 days after Kalmaegi typhoon (16-18, July). The activities of 210Pb and 234Th in the lower trap of T7KP mooring were an order less than that in T6KP mooring, indicating particles scavenge nuclides of the water column less effectively in wet season than in dry season. The absolute abundances of foraminifera in the canyon revealed that the biogenic particle was influenced by the terrigenous input and was different between dry and wet seasons. Seasonal variations of total flux and relative abundance of living foraminifera were evident in the upper 200 m water column near the Gaoping submarine canyon. Therefore, the seasonal variations of living foraminifera might be reflected on the biogenic particle transport in different seasons in the Gaoping submarine canyon.

It is generally understood that tidal currents ominated the flow field in many submarine canyons, and internal tide may be an order of magnitude more energetic than that of barotropic. The internal tide can be generated and amplified in a marine environment with the strong vertical density interface. The barotropic tides were known to play the dominant role in driving the internal tides at the topographic relief or shelf break.This research tries to look at the mechanisms of internal tides generation and propagation in the Kaoping Submarine Canyon off southwestern Taiwan, using Princeton Ocean Model (POM) with different settings. The model was tested with bottom topography of flat, a slope and real water depth, with and without vertical stratifications. The model settings are grid size 500m, simulate period days, radiation boundary condition at 4 sides. The model forcings are sea level variations at the west side, both semidiurnal tide (M2) and mixed tide (M2+K1) based on OSU tidal model TPXO 6.2. The results suggest that the offshore M2 tidal forcing can generate large internal tidal currents within the canyon with vertical density stratification. The internal tidal currents at the upper-layer of the canyon lag that of lower-layer 3~5 hours. There is no time lag and no amplification of current in the canyon if there is no stratification. There is a transition zone of minimum flow at depth of about 100-200m. Below the interface, the amplitude of semidiurnal internal tidal current increased with water depth in the canyon. The simulated density contours suggest a 120m amplitude vertical fluctuation center at 150m depth, with 5¢J temperature fluctuation. The computed baroclinic energy flux indicates that the energy in lower layer of the canyon is stronger than that of upper layer. The high energy flux appears at the canyon foot and rim, and propagates along the canyon axis landward.