This research collected surface (<15 cm) sediments from estuarine and coastal zones off southwestern Taiwan. Basic sediment parameters, including grain size, and total organic carbon (TOC) and total inorganic carbon (TIC) concentrations were analyzed. For heavy metals (Fe, Mn, Cd, Cu, Ni, Pb, and Zn), total metal concentrations and metal fractions separated by sequential extraction techniques were determined. This study also obtained several previously collected sediment cores in the Gaoping Canyon area that had been dated by other researchers. Results obtained in this study are used in order to understand the distribution patterns of heavy metals in coastal sediments off southwestern Taiwan, and related to regional environmental changes regarding heavy metals. The distribution of heavy metal fractions and their geochemical significances were studied. Results obtained in this study indicate that physicochemical characteristics of sediments largely affected heavy metal distribution in coastal sediments off southwestern Taiwan. Regional flow patterns contributed to the observed distribution patterns. Higher heavy metal concentrations were found in sediments collected near the Gaoping river mouth, the Gaoping Canyon and its nearby continental slope, and a narrow banded offshore region off the Anping-Tainan urban areas. These results reflect the distribution of fine-grained sediments in the studied area. Vertical profiles of heavy metals in four dated cores showed drastic increases of heavy metal concentrations since 1995-2000, and some extent of decreases during 2003-2006 in two of the cores. Although actions of environmental protection regarding heavy metal pollution had taken place in this region, decreases in sediment heavy metals were mostly attributed to episodic typhoon and possibly sediment slumping events. With the recently intensified landslides and mud flows in the upper reaches of the river that would bring upstream soils and particles to the estuarine region, leading to the decrease of metal concentrations in the Gaoping estuarine sediments, a more significant decreasing trend in sediment metal concentrations can be speculated for the future.

Geophysical, geochemical and geotechnical methods were used to investigate the spatial and temporal aspects of sediment distribution, accumulation, post-depositional alterations, and seafloor response and recovery to major events in a temperate, paraglacial, turbid outwash fjord. The goals of this study are to generate a complete geological model and compare the results to the global distribution of fjords. The over arching theme of this study is that the ratio of the area of the watershed to the area of the receiving basin can provide a first order indicator of many factors including glacial mass; the timing of glacial retreat; sediment input, accumulation, and preservation; and other factors. Temporal observations reveal the change of this fjord from a glaciated basin to and estuarine environment. These observations become important when viewed in the context of global climate change and the continued loss of ice. Preserved strata provide a 2800 yr record of changing modes of sedimentation as the system evolved from a glaciated basin to a non-glaciated fjord revealing a detailed chronology of change between end-member systems which can be used to infer changes as glaciers retreat from other fjords. Short lived radio isotopes were used to investigate post-depositional alteration of modern sediments. Without an understanding of how biological and physical processes work to modify sedimentary fabric during preservation, changes seen in sediment and rock core data cannot be accurately resolved. Physical processes can cause erosion and lateral transport; winnowing and armoring; and instantaneous sedimentation, all of which may be preserved. Biological processes can modulate the preservation of strata by destroying sedimentary fabric and integrating signals. The final fundamental need is to investigate the seafloor response and recovery to these events. Massive earthquakes are frequent in the study area and cause perturbations to sediment input and preservation. By understanding how lakes and deltas modulate sediment discharge after the event; how shorelines are modified after the event; and where sediment is deposited we can determine the influence these changes have on the environment and on humans.

An examination of suspended sediment concentrations throughout the Ganges-Brahmaputra River System was conducted to assess the spatial variability of river sediment in the world’s largest sediment dispersal system. During the high-discharge monsoon season, suspended sediment concentrations vary widely throughout different geomorphological classes of rivers (main river channels, tributaries, and distributaries). An analysis of the sediment loads in these classes indicates that 7% of the suspended load in the system is diverted from the Ganges and Ganges-Brahmaputra rivers into southern distributaries. Suspended sediment concentrations are also used to calculate annual suspended sediment loads of the main river channels. These calculations show that the Ganges carries 262 million tons/year and the Brahmaputra carries 387 million tons/year. These calculations are lower than published values because of either interannual variability and/or sampling artifacts and assumptions in the homogeneity of flow and sediment concentration. The conjoined Ganges-Brahmaputra River carries 530 million tons annually, or only 80% of the sum of the loads that the Ganges and Brahmaputra rivers carry upstream of the confluence. The remaining 20% of sediment is diverted from the main river by the distributaries and deposited along the main river channel during overbank flooding. Suspended sediment concentration is also examined in the north-south oriented tidal channels on the Bay of Bengal to determine whether sediment is delivered to the channels by one of two pathways: (1) sediment is discharged into the Bay of Bengal by the main river channel, carried west by coastal currents, and advected northward into the channels by tidal currents or (2) diverted from the main river bed through the distributaries, migrating southward into the tidal channels. Suspended sediment concentration and salinity data are inconclusive in determining sediment source. Beryllium-7 radioisotope data indicate that newly transported sediment is present in the tidal channels and offshore despite values in the Ganges and Ganges-Brahmaputra rivers being below detection. Sampling artifacts are likely caused by the below detection readings in the Ganges and Ganges-Brahmaputra rivers. Newly transported sediment is observed in a distributary south of the Ganges River and indicates that sediment is actively being transported to the distributary region.

The Port of Kaohsiung is the biggest harbor in Taiwan and also the fourth largest harbor in the world. There are several shipyards and fishing ports in the Port of Kaohsiung, therefore, the pollution of organotin should be very serious in the harbor area. In addition, there are Love River and Chien-Chen River pouring into the Port of Kaohsiung. This may be the second source of organotin pollution of the harbour of Kaohsiung. Seawater and sediment samples in the harbor of Kaohsiung were gathered in this research. Analysis on organotin contents were conducted to understand the distribution of the organictin in the Port of Kaohsiung. In seawater, the concentration of tributyltin (TBT) is between 170~480 ng/L, the concentration of dibutyltin (DBT) is between 150~400 ng/L and the concentration of monobutyltin (MBT) is between 80~283 ng/L. Working Duck and The Third Duck are among the serious areas of TBT pollution where the concentrations of TBT in seawater are over 350 ng/L. Concentrations of DBT and MBT are also the highest at the Working Duck. In the estuary areas, the concentrations of DBT and MBT are higher than TBT. It is probably due to the input of domestic sewage (Love River) and industrial wastewater (Chien-Chen River) which may bring extra DBT and MBT into the estuary areas. The highest TBT concentration in sediment is observed at Working Duck with average value of 25.3 mg/kg. This concentration is 4.5 times higher than that of Chien-Chen Fishing Port and 5.3 times higher than that of The Third Duck. All the concentrations of these three areas are over 10-d LC50 to bivalve (2.6 mg/kg) and amphipoda (2.1 mg/kg). The highest DBT and MBT concentrations are also observed in sediment of Working Duck, and the average concentration of DBT is 12.4 mg/kg and MBT is 9.7 mg/kg. In the estuary areas the concentration of organotins are lower than 1.2 mg/kg, therefore, the pollution of organotins is lesser serious in the estuary areas than the other sampling areas in Kaohsiung Harbor. The composition of organotins is mainly TBT in Working Duck, The Third Duck and Chien-Chen Fishing Port, and TBT accounts for more than 50%. TBT percentage decreases with sediment depth, however DBT and MBT percentage increases with sediment depth. It shows that TBT will be degraded for DBT and MBT gradually in the sediment. The trend that TBT percentage decreases with the sediment depth is not obvious in the estuary area, and the probable reason is that the source of DBT and MBT is not only from TBT degrading, but also from the input of city sewage and industry wastewater. According to this study, the content of organotins in sediment in the Port of Kaohsiung is indeed higher than other large-scale harbor (Barcelona and Port of Osaka). By comparing smaller areas, the content of organotins in Chien-Chen Fishing Port is also higher than marina of Hong Kong and German. It is concluded that the pollution of organotins in the Port of Kaohsiung is very serious in comparison with most other areas in the world.

Previous work in the Gulf of Lions, France has suggested that significant amounts of sediment may be escaping through the western part of this tectonically passive margin, despite it being far-removed from the primary sediment source (the Rhone river, ~160 km to the NE). It is hypothesized that the westernmost Cap de Creus canyon is intercepting the regional sediment-transport pathway and directing it offshore, allowing significant sediment export through this area. The overall goal of this project is to determine pathways and causes of sediment movement into Cap de Creus canyon to determine its role in off-shelf sediment export within the Gulf of Lions. Box cores were collected within the canyon and on the adjacent shelf on five cruises (2003-2005). Geochronology (210Pb-derived accumulation rates), grain-size distributions, and sedimentary structures (x-radiography) were analyzed to assess sedimentation patterns. Results indicate two mid-depth shelf depocenters (30-90 m water depth) separated by a zone of bypassing created by current acceleration around a headland. Within the canyon, the northern flank and mid-depth thalweg are modern depocenters of fine-grained sediments. The canyon head and southern flank are considered non-depositional for fine grains, although the head may be accumulating sands. Material enters the canyon from the northern rim (via advection of shelf benthic nepheloid layers), the southern rim (via dense-water cascading off the shelf), and through the canyon head (primarily coarse-grains). Budget calculations indicate that 9-23% of the sediment input to the Gulf is sequestered on the shelf and 1-4% is accumulating in upper Cap de Creus canyon. An ephemeral mud layer within the canyon axis indicates rapid deposition and frequent flushing, suggesting that sediment is moving through the upper canyon. This is also supported by high suspended-sediment concentrations associated with off-shelf dense-water flows. This study suggests that Cap de Creus canyon is an important conduit of sediment past the shelf break and the western margin is a primary location of sediment export from the Gulf of Lions.

This thesis examines the environmental conditions which led to the loss of 90% of the natural salt marsh in Galveston Island State Park since 1930 and analyzes one potential method to reduce future loss. Available data and recent studies suggest that the primary factor responsible for the historic loss was the lack of a sufficient supply of sediment to keep up with relative sea level rise. The average rate of sediment accretion for the period from 1963 to 2006 was measured to be 0.25 cm/year based on 137Cs and 239,240Pu nuclides. This rate is about 0.4 cm/year less than the relative sea level rise of approximately 0.65 cm/year during the same period. The marsh restoration project, constructed in 1999 at the Galveston Island State Park, focused on reduction of wave induced erosion and direct replacement of marsh substrate through terracing. The restoration project did not address the potential for marsh lost to submergence. As an alternative to geotubes or more permanent breakwater methods, a submerged sacrificial berm constructed around the marsh is a possible approach to address ongoing submergence. The sacrificial berm increases the available sediment supply by allowing partial transmission of waves to create a net transport of sediment into the marsh. In addition, the berm is designed to limit wave height in the marsh to reduce wave induced erosion. The proposed method involves iteratively adjusting the width and elevation of the berm top to maximize sediment transport from the berm into the marsh. A sediment transport model is developed to quantify the increased transport into the marsh, estimate a nourishment interval and qualitatively judge the expected berm evolution. The Galveston Island State Park marsh was used for demonstration purposes; however, the restoration concept and method of analysis is applicable to other marshes in Galveston Bay.

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2003. / Thesis advisor(s): Timothy P. Stanton, Edward B. Thornton. Includes bibliographical references (p. 79-83). Also available online.

Suspended sediments were collected from 3 rivers, the Rheidol, Ystwyth and Tywi on a regular basis. The sediment samples were studied for a number of physical and chemical properties to identify characteristics which might distinguish between source areas. These properties included mineralogy, magnetic properties, sediment colour, and the trace element composition of .sediments. Point-sources for heavy metals can be identified for all three catchments, and the metal content, and partitioning was studied. The metal content, and the site on the sediment to which the metal is bound has been found to vary with discharge. The response to discharge is not the same for all metals, but in general, at peak discharge the lead was in the Fe/Mn oxide and organic fractions, and these fractions became important for cadmium. Prior to the flood peak however, up to 70% of the cadmium was in easily exchangeable form. The organic fraction was the most important for copper throughout the flood. j Sediments which had been deposited in floodplain features and in lakes were also studied, as they recorded the pattern of sediment transport during floods over an extended period. In the Ystwyth catchment the metal content and ratios between metals was used to determine the importance of two mining areas for the supply of sediment to a floodplain during the mining period (1860-1890). Sediments from profiles in fossil alluvial channels on a floodplain in the Rheidol showed a dramatic increase in metal .concentrations in the mid-profile, and recorded the period of concerted mining in the catchment. Mining operations in the Ystwyth catchment caused widespread lateral aggradation of floodplains, as established at Trawscoed. The historic record of catchment changes as contained in the sedimentary profile of reservoirs in the Mendips was studied. The record in Blagdon and Chew Valley lakes in the Mendips was deciphered using a combination of sedimentological, magnetic and chemical data. A catastrophic flood which is documented for the area, which occurred in July 1968, caused the mobilisation and transportation of sediments from dry valleys in the catchment. Sediments deposited during the floods were distinguished by their coarse nature, by an increase in magnetic susceptibility and the parameter'S', which indicated a topsoil source, and by a change in the partitioning of lead and zinc, where the organic fraction was absent.

Continental shelves mark the zone between the terrestrial environment and deep marine realm and so are important for understanding sediment transport to the deep ocean. This study investigates the storage and potential record of the terrestrial environment on the Indus Shelf in the North Arabian Sea. The Indus Shelf records the development of clinoform sequences responding to sea level rise since at least the Mid Quaternary. Mapping of sedimentary and structural features established a clear link between sediment transport, deformation and sediment facies. Dome structures in the nearshore zone provide accommodation space on the slope for clinoform development through relative subsidence of neighbouring strata. All clinoforms contain partially eroded topsets formed during sea level fall. Multi-proxy analyses of two cores from the western shelf failed to establish a clear link between the continental record of provenance and weathering from the subaerial Indus Delta and the Indus Shelf system during the Holocene. The dominant source of sediment to the Indus Shelf appears to be erosion of Indus Delta sediments deposited during previous lowstands. During the Early Holocene some sediment is supplied to the north-west shelf from the Makran region due to the strengthening of the Asian Monsoon initiating the northwest to southeast longshore current and mixes with the Indus sediment. Estimates of mineral composition through a six end member algorithm further suggest very little relationship between provenance, weathering and published climatic records before sea level reached present levels. This thesis suggests that the Indus shelf, a high energy, a high sediment supply shelf, stores significant quantities of sediment derived from terrigenous sources. However, erosion and reworking processes mean that the record is not a good indicator of conditions in the terrestrial environment at the time of deposition.

The large surface area of cohesive sediments enables them to act as sinks for marine contaminants. Thus the dispersal of such contaminants is partly controlled by the resuspension and transport of fine sediments. The Cohesive Sediment Dynamics Study (COSEDS) group was established to gain a better understanding of the erosion, resuspension,t ransport and deposition of fine particulate matter, particularly during storm conditions. As part of this study, measurementso f wave heights and orbital velocities, near bed currents and suspended sediment concentrations were monitored using instruments housed on free-standing frames deployed in Morecambe Bay and on the Sellafield mud patch in the Eastern Irish Sea. Acoustic and Miniature Optical Backscatter Sensors (ABS and MOBS) were calibrated in a resuspension tank which allowed conversion of the raw backscattered field data into information on the size and concentration of the material in suspension. The contrast in particle size sensitivity of the ABS and the MOBS results in a big difference in the response of the ABS and the MOBS to the particle size distribution of the field site sediments. Thus, in an environment of mixed particle sizes, the ABS and the 'MOBS can be used in conjunction with one another to provide information about the suspended sediments. Hydrodynamic data from four sites on the Sellafield mud patch enabled shear velocity estimates to be made using the Inertial Dissipation Method. Time-series of drag. coefficient and roughness length measurementss howed both temporal and spatial variation in the observations. The spatial difference in the observations has been attributed to a change in the size distribution of the bed sediments between sites. The cause of the temporal variation in the observed roughness is thought to have been due to a changing flow regime, a combination of wave-current interaction and the presence of bed forms. Simple boundary layer models enabled the reproduction of the shear velocity values and the drag coefficient in both rough-turbulent, smooth-turbulent and transitional flow regimes. The direct relationship between the suspended sediment and the tidal currents indicated local erosion and, pickup from the seabed. The optical backscatter data revealed the resuspensiono f sedimentb y waves at times of high orbital velocities and by tidal currents at other times. Estimateso f suspendeds edimentf lux were computed from the product of the vertical integration of velocity profiles and concentration profiles, which were predicted assuming a Rouse-type profile. Flux estimates at each of the sites indicated a net movement of sediment northwards throughout the duration of the two week deployment. For a more detailed picture of transport patterns, and hence contaminant paths, it has been shown that nearb ed hydrodynamicm easurementsa re required for a longer time period