SENIOR RESEARCH PROJECTS
SUMMARIES OF STUDENT RESEARCH PROPOSALS
School of Oceanography, University of Washington
The summaries are listed alphabetically by author. Please remember that the research of any project may change during the study from what is summarized here, owing to vagaries in Nature and to unanticipated changes in operations (including Murphy's Law). Even titles of projects may change. This is a part of doing scientific research.
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The scarcity of intertidal habitat in the Duwamish River, and its ecological value as a buffer and a feeding grounds for salmonids, shorebirds, and other wildlife, suggests that the intertidal is a resource which should be more intimately understood. I want to look at what sorts of changes can be expected when habitat is restored to some semblance of its original state. The Port of Seattle has created such a site at the Duwamish River-end of Diagonal Way, just south of downtown Seattle. Their primary interest is in increasing food supplies for young salmon, so I plan to focus upon the same prey species as has previous research. By the same token, if habitat changes alter the food supply for young salmon, the food supply for several other wildlife species will probably be similarly affected.
The primary objective of this study is to evaluate the effects of intertidal habitat restoration on a selected epibenthic faunal assemblage at the Diagonal Way habitat restoration project. Biological data collected prior to site restoration and data obtained two and three years after the restoration are available for analysis. This information will be combined with the sampling of this study, which is ten years after the restoration. The latter research will provide additional information concerning long term dynamics of the intertidal habitat. The previous experiments were conducted by contract for the Port of Seattle, and the data has been made available. The previous sampling will be repeated using an epibenthic suction pump to extract specimens larger than 0.253 micrometers from the surface sediment. Samples will then be preserved for examination under a disecting microscope. Particular species, primarily salmonid prey species, will then be enumerated and compared to results of previous research at the site.
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The objective of this project is to examine the salinity structure of the surface water in Elliott Bay and to check the surface layer's response to local winds. The Duwamish River plume will be identified by its low salinity. The research vessel will run repetitive tracks around Elliott Bay recording salinity and location. This will provide data for mapping the migration of the plume with time. Measurements at depth will determine the vertical thickness of the freshwater layer at different locations. These data will be used to make volume calculations of the plume. The above information will be compared to the local wind speed and direction to see how wind influences plume development. The results from this investigation will be used to confirm current theory and provide background information useful in determining the extent of mixing in the surface layer as well as the associated dispersion characteristics of anthropogenic chemicals, organics, and suspended solids introduced into Elliott Bay via the Duwamish River.
The objective of this project is to examine the temporal migration of the Duwamish River plume within Elliott Bay by analyzing surface-salinity structure during different phases of the tidal cycle. The methods will include repetitive quasi-synoptic sampling of surface salinity to identify river plume fronts and features. Also, periodic depth-profiling of salinity will be performed to determine the thickness of the associated freshwater lens. All spatial data will be indexed using the Differential Global Positioning System (DGPS) in order to facilitate mapping. The associated sub-mesoscale wind vector-field will also be analyzed for correlation with the temporal plume migration. A comparison between depth-integrated surface transport and riverine-based mass-balance calculations will be performed to verify continuity. The results from this investigation will be used to confirm current theory and provide background information useful in determining the extent of mixing in the surface layer as well as the associated dispersion characteristics of anthropogenic chemicals, organics, and suspended solids introduced into Elliott Bay via the Duwamish River.
Please follow my progress in this research by means of my Progress Notices after 9 April.
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This project attempts to find out where the copepod Eurytemora americana, a planktonic crustacean, lives within the Duwamish River Estuary. Finding where these copepods reside may give an indication of how they are able to stay within the estuary without getting flushed out of the river. A possible means of staying within the estuary involves moving up and down to ride the opposite flowing currents, upstream at depth and downstream in the upper layers of the river. To know where it is, E. americana may use physical signals such as current flow or salinity and move to areas where these signals are appropriate.
In addition to finding out how this copepod stays in the estuary, finding out where the copepod lives will help other researchers in their possible studies of the ecosystem. Other studies may involve the transfer of pollutants from the river to the copepods, a source of food for juvenile fishes that use the river as a highway between their breeding grounds and Puget Sound.
Water samples will be taken with a pump and filtered through a 100 micrometer mesh to catch the animals. This sampling will be done at various spots in the river and at different depths and salinity levels in the water. Adult female copepods will be counted to determine the relative densities of copepods in each water sample. The highest densities are expected to be found where the salt and fresh water masses meet.
In order to assess the distribution of Eurytemora americana in the Duwamish River Estuary, samples will be taken by means of a submerged pump throughout the salt wedge. At high slack tide, multiple stations will be sampled at three different salinity levels: one at the surface (S<5), one in the layer of maximum salinity gradient (5>S>22), and one within the marine layer (S>22). On the flooding tide, a single station will be sampled at three different depths as the salt wedge moves upstream. Prior to the sampling at each station, a CTD and turbidity profile will be made to assess the physical properties. The copepod distribution will be compared to the salinity structure, the turbidity structure, and the current velocity profile in the estuary. The highest densities of E. americana are expected to be associated with the turbidity maximum and to be found in the high salinity gradient areas of the salt wedge toe in between the opposing flows of fresh and salt water masses.
This distribution study is to be a possible baseline for studies involving this and other populations of enduring resident zooplankton within estuaries. Future and ongoing research may involve the mechanisms of copepod retention, the transmission of particle-attached toxicants via E. americana in estuarine environments, and the use of resident zooplankton as indicators of toxicant levels.
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This study will determine the volume of mixed-water surface outflow through the East Waterway over a tidal cycle. The aim of this study is to determine the volume of the Duwamish River water that splits into the East and West Waterways. The hydrography of the circulation over the sill in the East Waterway will also be surveyed. The physical understanding of the stratification of fresh, mixed, and salt water at the sill will be utilized to understand the dynamics of river outflow as it is linked to tidal control.
This project will calculate the fresh water flow through the East Waterway over a tidal cycle and describe the hydrographic conditions existing over the sill located at the southern end of the East Waterway. The assumed split of fresh water flow between the East and West Waterways is approximated at a 20/80 split respectively (Shawk, METRO lecture). This study seeks to quantify the fresh water flow and affirm that the 20/80 ratio is a sound approximation. The presence of a shallow sill (4m) at the south end of the waterway is assumed to prevent the intrusion of the salt wedge from the East Waterway into the Duwamish River estuary and is assumed to have an impact on fresh water flow through the East Waterway due to tidal height variance over the sill. To obtain the data for this study two approaches will be used. Five CTD and current meter stations in the East Waterway and Duwamish River will be used to describe the hydrography in the East Waterway. The Spokane Street Bridge over the East Waterway will be utilized as a platform for three CTD and current meter stations over the sill. Two stations will be located at the northern slope of the sill. All stations will measure over a tidal cycle. The environmental impact of the suspended load in the Duwamish River can be seen in the toxic levels of sewer overflow pollutants discharged into the river (R. Shuman, Ocean 460, 10 January 1996). If the current velocities decrease at the sill, then a fraction of the suspended materials may settle out and deposit on the sill. If materials are toxic the sill may act as a sink for contaminants.
Please follow my progress in this research by means of my Progress Notices after 9 April.
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The Seattle Fault is an east-west trending thrust fault that is shoving older rocks northward on top of younger rocks in the local Seattle metropolitan area. Evidence for movement along the fault about 1000-1100 years ago includes uplifted marine terraces west of Seattle at Restoration and Alki Points and earthquake-generated tsunami deposits north of Seattle at Cultus Bay and West Point. An uplifted estuarine terrace at the mouth of the Duwamish River (5 km SW of Seattle) may have coincided with the earthquake that produced these other local landforms. The primary objective of this proposed research is to determine whether or not these estuarine deposits record earthquake-induced uplift about 1000 years ago.
The tidal flat will be identified by the bivalve assemblage, plant fossils, and composition and grain size of the sediments. A coring device will be used to determine the upper boundary of the estuarine deposit. A horizontal land survey will enable a determination to be made of the vertical displacement of this tidal flat relative to present-day mean lower low water. Ages of the uplift will be estimated from radiocarbon dates of woody material in the deposit and from the dates of archaeological artifacts recovered at the project site by previous workers. If the tidal flat displacement can be attributed to faulting, then this project will extend the evidence for sudden uplift eastward of that previously obtained at Restoration and Alki Points. This knowledge will contribute to the understanding of prehistoric earthquakes in the Puget Lowland and can be used in refining models of the response of sites in this heavily developed area.
An uplifted estuarine deposit at the mouth of the Duwamish River may have coincided with the earthquake that raised marine terraces at Restoration and Alki Points, Washington. The primary objective of this proposed research is to determine whether or not these estuarine deposits record earthquake-induced uplift about 1000 years ago. The tidal flat will be identified based on the bivalve assemblage, plant fossils, lithology and grain size of the sediments. The site will be cored with a hand auger to determine the upper boundary of the estuarine deposit. A horizontal land survey will enable a determination of vertical displacement relative to present-day mean lower low water. The age of uplift will be constrained by radiocarbon dates of woody material in the deposit and those obtained by previous studies of archaeological artifacts recovered at the project site. If the tidal flat displacement can be attributed to faulting, then this project will extend the evidence for sudden uplift eastward of that previously obtained at Restoration and Alki Points. This knowledge will contribute to understanding of prehistoric earthquakes in the Puget Lowland and can be used in refining site-response models for this heavily developed area.
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The fresh water from the Duwamish River should have a different temperature from the Elliott Bay water into which it flows. This project will attempt to use images from a helicopter-mounted heat sensor to locate how far the fresh water intrudes into the bay. When the position of the plume is related to wind and tide conditions taken at the same time, it will give an indication of how far any contaminants in the river water might get into the bay.
The objective of this project is to track the fresh-water plume from the Duwamish River as it mixes into Elliott Bay in Seattle, WA. Synoptic views of the plume will be obtained from a helicopter-mounted thermal imager. Ground truth will be obtained by doing surface temperature and salinity measurements along the coastline of Elliott Bay from Harbor Island to Elliott Bay Park and in various locations within the bay
Contaminants carried downstream by the river are deposited along the way or carried into the bay by the plume. Tracking the position and structure of the plume will serve to verify circulation models of the bay and help in the development of a map of depositional areas within Elliott Bay.
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Ferry traffic is a regular feature of Elliott Bay. As the ferries move through the water, they cause disturbances that trail behind the ferry, spreading and sinking as the distance from the ferry increases. This disturbance will increase the mixing of water masses in the bay, and we are particularly interested in the mixing of the fresh water from the Duwamish River as it circulates around Elliott Bay. As the individual ferry wake effect is determined, it can then be multiplied by the number of ferries traversing the bay in a day, calculating a daily contribution to mixing by ferry traffic.
How is the structure and position of the fresh water plume, as it circulates through Elliott Bay, affected by the regular passage of ferries through the bay? Contaminants carried downstream by the river are deposited along the way or carried into the bay by the river plume. The extent of the total mixing in the bay will give an indication of how quickly anthropogenic chemicals are diluted and how far these contaminants travel before being diluted. The rate of mixing is also related to the type of sediment deposited over the area. There may be a relationship between the disruption of the surface layer by the ferry traffic and a possible depositional region beneath the ferry traffic lanes running through the bay. The contribution to mixing by the ferry prop wash and the hull wake may be a significant portion of the total mixing in Elliott Bay.
The extent of the wake vortex will be measured using a CTD mounted in a container that is continuously supplied with surface water through a shipboard pump system. The pump system draws water through an inlet in the hull of the boat, below the water line. This method will provide surface profiles of salinity changes as the boat travels back and forth through ferry wakes, with the ferry moving away. The CTD will also be lowered and raised within the ferry wake for vertical profiles of salinity changes from the wake effect. This collection of data will be used to determine a three-dimensional cone that will represent the extent of the wake disturbance as the ferry passes. The cone dimensions multiplied by the number of ferry passages per day will give an indication of the ferry's contribution to the total mixing in the bay.
Please follow my progress in this research by means of my Progress Notices after 9 April.
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Diagonal Way, a small embayment in the Duwamish River, Washington, is one of King County/Metro's future sediment cleanup sites: the sediments are so contaminated that King County/Metro will need either to dredge the contaminated sediments (i.e., dig up and completely remove them from the system), or to cap the sediments (i.e., to lay clean sediment on top of the contaminated sediments). In order to determine the best choice of cleanup method, it is important to know whether the area is erosional or depositional. If the site is erosional, a sediment cap can be quickly washed away, but if the area is depositional, contaminated sediments may be deposited on top of the clean sediment cap. In this study, water velocity above the river bed at a particular location will be monitored and used to determine whether erosion could be occurring The general flow and water characteristics throughout the study area will also be determined by measurements of characteristics such as temperature, salinity, and velocity at depths below the surface of the water. The results of this study will be compared with the results of a study by Erich Rehberg that will use sediment characteristics at the site to determine what the currents were like in the past. When combined, the results of these two studies will provide implications for the best solution for cleaning up the sediments. If a cap is chosen, the results may also indicate what type of sediment will be most appropriate for the cap
The flow regime near the Diagonal Way cleanup site in the Duwamish River, Washington, will be determined and used to provide recommendations for coming sediment remediation projects by King County/Metro. First, the flow and hydrographic characteristics of the site will be determined by taking velocity, turbidity, and CTD profiles at various stations throughout the the cleanup site during periods of maximum current velocity. Additionally, one 12-hour time series of velocity, turbidity, temperature, and salinity will be taken 50 cm off the river bottom to determine whether the threshold of grain motion is exceeded, given the characteristics of the bottom sediment. A grab sample of the sediment at the time-series location will provide the required sediment size information. The flow regime and predictions concerning erosion probability obtained here will be compared with results obtained through a determination of the depositional environment based on sediment distributions (Rehberg, work in progress). The estimates of these two studies will provide implications for future sediment remediation, highlighting in particular the benefits of using a sediment cap to cover contaminated sediments versus dredging to remove the sediments. The most effective sediment size to use for a cap, if that method were chosen, will also be indicated. A lack of any previous measurements of the flow characteristics at Diagonal Way make this information particularly useful.
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The Duwamish River is composed of two layers: a fresh water layer that rides above a deeper saline layer. The objective of this project is to characterize the mixing between these two layers. Specifically, the mixing is to be examined at the "toe" of the salt-wedge, which is near a sharp topographical change at the up-stream end of the dredged river channel. The goal is to ascertain if, and when, intense mixing events occur at the salt-fresh interface, as has been suggested by previous studies. These mixing events, if present, are very important to determining how long chemical and biological material remains in the river, as these times would differ from those resulting from the continual mixing that is typically assumed and used in models of the river (e.g., by Metro).
The objective of this project is to characterize the mixing between the deep saline and surface fresh water layers of the river. Specifically, the mixing at the "toe" of the salt-wedge, which is near a sharp topographical change at the up-stream end of the dredged river channel, is to be examined. The technique used will be either an echo-sounder sensitive enough to detect mixing between the the two layers with a few CTD casts to determine the actual salinities, or extensive CTD casts to characterize all parts of the water column. The goal is to ascertain if, and when, intense mixing events occur at the salt-fresh interface, as has been suggested by previous studies. These mixing events, if present, are very important to determining chemical and biological residence times in the river, as the times would differ from those obtained by the continual mixing that is typically assumed and used in models of the river (e.g., by Metro).
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Turbidity currents are density-driven flows that occur when fluids of differing densities flow into one another. Some examples we are familiar with include powder-snow avalanches, the intrusion of fresh riverine water into the ocean, and oil spreading over water. In the oceanic environment, much of the sediment removed from shelves and redeposited in deeper water is transported by turbidity flows rather than surface water currents, waves, or tides. As in the avalanche example, gravity acts on each particle within the turbidity current inducing downslope flow. The less dense overlying fluid (air) is entrained, and acts to reduce the friction between the flow and the bed. The particles are maintained in suspension by turbulence, and the flow is capable of traveling great distances.
I believe turbidity currents are active in the sea-valley system in Elliott Bay, and that this process plays an important role in the mobilization and transport of sediment-borne contaminants into the main basin of Puget Sound. In order to investigate this phenomenon I will use two separate, yet integrable, approaches.
The first involves using a sub-bottom profiler to map the sea-valley system in Elliott Bay. This will not only show the bottom of the bay, but underlying depositional layers as well. The angle, location, and sequence of these layers will be used to estimate the velocity of the flow that deposited these layers and the amount of sediment transported by the flow. Piston cores will be used to examine the layers in order to estimate the frequency of the turbidity currents.
The second method involves generating historical profiles of the bottom of Elliott Bay using maps dating from 1875 to the present, and locating areas of erosion and deposition.
Within Elliott Bay, turbidity currents pose a hazard for cables, piers, sewer outfalls, and dredge-disposal sites. Once mobilized by turbidity currents and injected into the deep waters of the main basin, potentially contaminated sediments become entrained in a circulation that involves both deep and surface waters. Sediment-borne contaminants travelling in this manner would be exposed to both marine and human populations.
Turbidity currents, among other mechanisms of mass transport, may be active in the sea-valley system in Elliott Bay. This process could be partially responsible for the growth of the Duwamish Fan, and plays a role in the mobilization and transport of sediment-borne contaminants into the main basin of Puget Sound. These transport phenomenon will be explored using two separate, yet integrated approaches: geophysical imaging and paleobathymetric analyses. Piston coring and seismic reflection data will be used to locate and sample turbidity-current depositional features, whereas paleobathymetric cross-sectional profiles, reconstructed from data dating to 1875, will show areas of erosion and deposition. Within Elliott Bay, turbidity currents pose a hazard for cables, piers, sewer outfalls, and dredge disposal sites. Once mobilized by turbidity currents and injected into the deep waters of the main basin, potentially contaminated sediments become entrained in a water mass whose residence time encompasses both deep circulation and surface exposure. Sediment-borne contaminants travelling in this manner may have severe impacts on benthic, pelagic, and human populations.
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Copepods are small crustaceans that live in both marine and fresh water regions. If exposed to trace metals, these animals can potentially ingest and store these contaminants in their tissues, and transfer the metals up the food chain. Little information is known about the marine copepods found in the Duwamish River Estuary, and these copepods have never been analyzed for trace metals. In order to determine what the copepods in the estuary are exposed to, this research is focused on trace metal concentrations in two species of copepods which live in the Duwamish River Estuary. Eurytemora americana spends its entire lifecycle in the estuary and Pseudocalanus spp. inhabits the estuary, Elliott Bay, and the Main Basin of Puget Sound. Samples of copepods will be taken from these locations and they will be analyzed for trace metals. Determination of significant concentrations of several trace metals in these copepods would show that these animals are potential transport agents of these contaminants out of the estuary and into the Main Basin of Puget Sound.
The objective of this research is to determine if there are significant concentrations of trace metals in copepods, and if copepods are potential transport mechanisms of these contaminants out of the estuary and into the Main Basin of Puget Sound. Net tows will be used to collect Eurytemora americana in the Duwamish Estuary and Pseudocalanus spp. from the estuary, Elliott Bay, and Main Basin of Puget Sound. Inductively Coupled Plasma Mass Spectrometry (ICPMS) will be used to determine the concentration of several trace metals in these copepods. Detection of significant concentrations of trace metals in these animals would show that copepods are a potential contaminant transport agent out to the Main Basin of Puget Sound.
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The sea surface layer (SSL) is a very thin layer of water located at the surface of a body of water. The SSL is the site of many chemical interactions between the ocean and the atmosphere. It is also an important habitat for the larval stages of many commerically important fish, crab, and other sea creatures. However, studies have shown that the SSL also concentrates microscopic-sized metals. These metals could come from the burning of fossil fuels, for example, and are toxic to many animals, terrestrial as well as marine.
The objective of this research is to determine if there is a correlation between increased metal concentrations in the SSL and the abundances of the marine life in those habitats. This will be achieved by taking SSL samples from sites which contain varying concentrations of metals and comparing those concentrations to the marine life present. In ordet to get samples with varying concentrations of metals, two sites in Washington state will be sampled: Elliott Bay and Sequim Bay. Elliott Bay is located near Seattle in the Puget Sound area and is subjected to run-off and air pollution from the surrounding industry. Sequim Bay is located on the Olympic Pennisula in a much less-industrialized area. Previous studies by Jack Hardy have shown that these two bays have very different metal concentrations, making them ideal sites for this study.
The samples gathered at these two sites will be analyzed for metals, and the different types of marine life present will be counted while viewing the samples under a microscope.
The objective of this research is to determine if there is a correlation between metal concentrations in the sea surface layer (SSL) and the type and abundance of the biota inhabiting the SSL. This will be determined by taking six samples from two bays in Washington state that having similar physical features but have different SSL metal concentrations: Elliott Bay and Sequim Bay. Elliott Bay is located in the highly industrialized area of Seattle and is subjected to run-off and air-pollution, both of which are sources of metals. Sequim Bay is located on the Olympic Pennisula, in an area much less-industrialized than that of Elliott Bay. A previous study by Jack Hardy showed that these two bays had very different SSL metal concentrations, making them ideal for this study.
Each sample will be analyzed for metals, (lead, mercury, cadmium, and copper), using the ICP-MS method. Bacterial counts, chlorophyll-a measurements, and larval counts will be taken from each sample. Bacteria and larval stage counts will be done using microscopy, while chlorophyll-a will be measured using a fluorometer. Any correlation between the enrichment of metals in the SSL and the type and abundance of the biota inhabiting the SSL should become apparent from these data.
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I am studying two highly polluted sites in Elliott Bay. These two sites have been capped, that is covered with clean sediment to protect the animals living in the area from the harmful effects of the pollution. I am looking at the new animal communities now living on this clean sediment and I shall determine if these communities have followed natural succession. Succession is defined as the changes seen in the animal community after some disturbance opens up an empty space of ground to be colonized. This study is important to help determine if capping is a good method of excluding animals from the harmful effects of marine pollution.
In this study I shall examine two sediment capped sites in Elliott Bay to determine if natural community succession has occurred. Succession is defined as the changes seen in the animal community after a disturbance has opened up a large patch of land for new colonization. Metro (Municipality of Metropolital Seattle) is the agency that put the caps in place, and King County/Metro is responsible for monitoring the caps and analyzing their effectiveness. Metro scientists have collected benthic samples from designated sites on the caps and a private consulting company has determined the taxonomy of the samples. Metro has been unable to analyze these data to determine the "health" of the benthic communities, but there is a need for this information to help determine if sediment capping is an effective remediation effort. The two sites will be compared both with each other and with pre-cap data using the number of species recovered, the number of individuals of each species present, and the types of species found. This comparison will form the basis for determining if natural succession has occurred.
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Mercury is a trace metal of concern in Elliott Bay because of its high concentrations in both the sediments and water column and its toxic effects on humans. Although concentrations in the sediment have declined since the 1950's (period of maximum mercury concentration in sediments), they are still high. The objectives of this study are to determine the historical trends of mercury deposition in Elliott Bay sediments and to determine whether the sediments along the north shore of the bay record a signature of the Denny Way Combined Sewer Overflow site (a mercury "hot spot"). This study is important because few historical trend studies have been conducted in Elliott Bay. Results of previous studies from the Main Basin of Puget Sound may be different from Elliott Bay because of different flow conditions, circulation patterns, and the presence of industrial and commercial discharge directly into the bay. Sediment accumulation rates will be determined to correlate sediment depths to the year of deposition. Mercury concentrations will then be determined for each depth/period of time.
The objectives of this study are to determine the historical trends of mercury deposition in Elliott Bay sediments and to determine whether the sediments along the north shore of the bay record a signature of the Denny Way CSO. Mercury was chosen because it exceeds the U.S. EPA standards for human health and all forms are toxic to humans and other higher animals. Methylmercury, an organic compound produced by microorganisms, is the most toxic form and has great potential for bioaccumulation in the tissues of fish and shellfish. Sediment cores (8 feet long and 2 inches in diameter) will be taken with a piston corer from the north shore of Elliott Bay, just southeast of the Denny Way CSO and from the ridge between the two main canyons of the bay. Cores will be analyzed for lead-210 activities to determine sediment accumulation rates. Mercury concentrations will be determined by ICP mass spectrometry and will include mercury bound in Fe and Mn oxides and organic matter and mercury absorbed onto mineral surfaces. Results will be compared to previous studies conducted in the Main Basin of Puget Sound (Bloom and Crecelius, 1987; Lefkovitz et al., 1995). These studies show that mercury concentrations began increasing above background levels (less than 0.1 ppm) in the late 1800's, reaching a maximum of about 0.3-0.5 ppm during the 1950's, and declined significantly through the 1960's and 1970's. Concentrations in Elliott Bay are expected to be higher due to the proximity of the sources and possibly start increasing earlier than in the Main Basin, as the Seattle area was one of the first areas to develop on Puget Sound.
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Animals living in estuaries are exposed to rapid fluctuations in environmental conditions. The tide pushes salt water upriver and draws it out again on a daily basis, while the river feeds the estuary with a constant supply of fresh water. Marine organisms are significantly affected by relatively small changes in their environment, such as the amount of salt dissolved in seawater. Animals inhabiting estuaries must therefore have a tolerance for a wide range of salinities. Eurytemora americana is a copepod, or very small crustacean, found in the Duwamish River Estuary, WA. A sample of these copepods will be collected from the river and exposed to different salinities in a laboratory experiment. The copepod's protein composition will be studied for each salinity treatment, since there may be a correlation between environmental stress and the production of new proteins in the copepod. A separate laboratory experiment will be carried out in an attempt to establish if E. americana is particularly suited for a specific salinity. Understanding how natural environmental variables affect these important animals in the estuarine zooplankton community is essential for future detection and identification of artificial variables such as toxic exposure.
The objectives of the proposed research are to determine if the calanoid copepod Eurytemora americana occurring in the Duwamish River Estuary is capable of rapid adjustment to a large range of salinities and if specific proteins are produced in response to salinity change. Field-collected adult female E. americana will be exposed to a range of salinities, and copepod proteins will be extracted and separated by gel electrophoresis to detect any newly synthesized proteins which may be associated with acute response to salinity stress. Survival of copepods exposed to various salinities will be monitored over time in a separate laboratory experiment to determine if there is an optimum salinity. Copepods are significant members of the estuarine zooplankton community and understanding how natural environmental variables affect the animals is essential for future detection and identification of artificial variables such as toxic exposure.
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Between 1972 and 1987, contaminated sediments dredged from the Duwamish River in Seattle were dumped at the Fourmile Rock disposal site in northwestern Elliott Bay. The disposal site is located on a submarine slope approximately 1100 yards (1000 meters) offshore. The dumping at the site has contaminated areas outside of the disposal site along the northern submarine slope of Elliott Bay. Previous research has found evidence of submarine landsliding approximately 1200 yards (1100 meters) to the northwest of the site. The presence of sliding in the vicinity of the disposal site suggests the possibility of continued sliding along the slope in the future. A large submarine landslide in or around the disposal site could transport contaminants into the near-bottom currents of Puget Sound. Small slides could disperse contaminants over a wider area downslope of the disposal site. A seismic profiler will be used to produce a cut-away view of the layers of sediment underneath the sea floor. From these images, areas that have undergone submarine landsliding can be located. The data obtained from the subbottom profiler and analyses of bottom sediment samples will be used to: identify areas that have undergone submarine landsliding, determine the likelihood of submarine landslides at the disposal site, and determine if the dumped sediments have slid towards the deeper waters of Puget Sound.
Between 1972 and 1987, the Fourmile Rock dredge spoil disposal site in Elliott Bay served as an unconfined disposal site for contaminated sediments from the Duwamish River in Seattle. The disposal site is located on a 13-degree slope approximately 1100 meters offshore. The area surrounding the disposal site is also contaminated due to the spread of particle-bound contaminants in the water column during dumping. A previous geophysical survey of outer Elliott Bay found evidence of slumping approximately 1100 meters to the northwest of the site. The presence of slope failure in the vicinity of the disposal site suggests the possibility of continued slope failure along the slope in the future. A large submarine landslide in or around the disposal site could transport contaminants into the general circulation of Puget Sound bottom water. Small-scale sliding could disperse contaminants over a wider area into the deeper areas of outer Elliott Bay. Seismic reflection data and analyses of sediment obtained by piston coring will be used to: identify areas of slope failure, assess the stability of the disposal site, and determine if dredge spoils have slid down the gradient towards the Main Basin of Puget Sound.
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My hypothesis is that mussels living in urbanized sites in Elliott Bay, Washington, grow more slowly than mussels living in relatively non-urbanized sites. An urbanized site is one where larger human population and industry have more than likely contributed to a build-up of pollutants that may have harmful effects on water quality. It is important to assess the effects of urbanization because, if the mussel is being harmed, other animals may be harmed as well.
Mussels will be collected from sites within Elliott Bay, urbanized sites, and also outside of Elliott Bay in more pristine areas, non-urbanized sites. At least fifty mussels will be sampled from each site. Measurements of each mussel's shell length and soft tissue weight will be recorded as well as each mussel's age. By comparing the growth related measurements with the age of each mussel, I shall be able to determine an approximate growth rate for the mussels at each site. The growth rates will then be used to test my hypothesis.
The objective of this study is to relate the growth parameters of shell length, total tissue weight and the age of mussels, Mytilus edulis, from both urbanized and non-urbanized areas to determine if anthropogenic contamination affects mussel growth. My hypothesis is that mussels growing in urban sites known to contain moderate to high levels of anthropogenic contaminants will have a slower growth rate than mussels inhabiting more pristine areas. Samples will be collected at several urbanized sites in Elliott Bay and the Duwamish River mouth. Reference sites, representing non-urbanized sites, have been chosen to reflect similar estuarine properties that exist in Elliott Bay. This study may provide insights into possible effects that urbanization within the Duwamish River and Elliott Bay has on benthic intertidal organisms. The assessment of mussel health is important because, if mussels are biologically impaired by anthropogenic contaminants, there are likely to be other, more sensitive, organisms adversely affected as well.
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Sediment distribution from the Diagonal Way cleanup site in the Duwamish River, Washington, will be determined and the sediments analyzed using standard geological techniques. The data will provide valuable information for Metro's sediment remediation project. Forty-two sediment samples from the Diagonal Way area will be analyzed for size distribution. From the distribution data, estimates will be made of the depositional environment.
The objective of this study is to analyze the sediment dynamics in the area surrounding the Diagonal Way combined sewer overflow (CSO) on the Duwamish River. An emphasis will be placed on analyzing sediment data, previously gathered by Metro, to help describe the physical environment, in which the sediments were deposited. The sediments will be analyzed using standard geological techniques, combined with the Passega method, which will establish relationships between texture of the sediment and the processes of deposition. This information will be compared with the independent analysis (Dail, work in progress) of velocity profiles and bottom velocity time series in the same area. This information will be useful to Metro in its proposed sediment remediation in this area.
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This project will measure the concentrations of silver, cadmium, chromium, copper, lead, mercury, nickel, thallium, and zinc in the waters of the Duwamish River Estuary. A set of six samples will be taken at shallow depths in regions of fresh, brackish, and salty water. Each sample will be filtered and separated into three categories (subsamples): 1. Metals attached to larger particles. 2. Metals attached to smaller particles. 3. Unattached metals dissolved in water. All subsamples will be analyzed for metal content and the importance of each category for each different element determined. This project will investigate what effect the change from fresh to salt water has on how metals are distributed into the above categories, as well as provide distribution ratios (partition coefficients) for each element. The results of this project could be important in predicting the spread and fate of toxic metal contamination from the Duwamish River into Elliott Bay and Puget Sound.
This project will investigate the effect of the salinity gradient on partitioning between the dissolved, colloidal, and particle-bound phases of 8 toxic trace metals (silver, cadmium, chromium, copper, lead, mercury, nickel, thallium, and zinc) in the water column of the Duwamish River Estuary. Six surface layer water samples will be collected along the axis of the river to span the salinity range. Each sample will be phase-separated via pressure filtration and ultrafiltration. These size-fractionated subsamples will be analyzed for metal concentrations by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), using a Flow Injection Preconcentration method developed by T. Chapin (Chapin, 1996). These data will be used to determine partition coefficients (Kd) for each metal. Data analysis will focus on the following four questions:
The partition coefficient values provided by this project will contribute to future hydrodynamic and toxicant fate modeling of the Duwamish Estuary (R. Shuman, pers. comm., 1996). This project will also provide the first partitioning data for the colloidal phase of the above metals in the study region.
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The objective of this study is to determine trace metal concentrations in Duwamish River sediments and to relate that concentration to the size, surface area, and organic carbon concentration of the sediment. Since smaller grain sizes have a larger surface area to which metals can adsorb, metals may be concentrated in areas dominated by smaller grains. Metals may also adsorb to organic carbon associated with sediment surfaces. These processes are related because organic carbon concentration may be associated with surface area as well (Mayer, 1988). Small particles stay in suspension longer than large particles, and thus are more likely to be deposited in areas outside of the Duwamish River Estuary. Knowing the factors controlling the adsorption of metals onto sediments in the Duwamish River Estuary may explain why certain areas are more, or less, polluted than others, and the same ideas may be applied to other estuarine systems as well. The metal/size relationship will provide information to biologists studying animals that eat particles of certain sizes, and physical oceanographers studying erosion and deposition of sediment on the bottom of the estuary.
The objective of this study is to determine the relative importance of organic carbon concentration, surface area and grain size of sediments in determining trace metal concentration of surface sediments in estuaries. Sediment samples will be obtained along a salinity gradient in the Duwamish River Estuary, Washington, as well as from a fresh water and marine end-member. The sampling sites will correspond with those of Sean Steen and Yoon Kim, as they will be sampling the water column to study trace metals. Sediment will be fractionated into sand (>250, 63-250 micrometers), and silt (38-63, 15-38, 8-15, and 3-8 micrometers). Wet sieving will be used to separate the first three sizes, the last three will be hydrodynamically separated using split flow, thin cell, lateral transport (SPLITT). Surface area will be determined using the BET surface area technique. Organic carbon will be determined with a CHN analyzer. The concentration of several metals will be obtained, after partial digestion, with Inductively Coupled Mass-Spectrometry (ICP-MS). Trace metal analysis will include Chromium, Lead, Cadmium, Silver, Nickel, Copper, Zinc, and Thallium, which are anthropogenic metals of concern in the Duwamish. The relationship between sediment size and trace metal concentration is valuable for determining areas in the Duwamish that are, or may become, hot spots for deposition and burial of metals and contaminants. Biologists may also be concerned with the metal/size relationship when considering the concentration of metals in the tissues of suspension feeders or benthic organisms.
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Copepods are small (~ 1mm) marine crustaceans that are thought to usually eat particles and phytoplankton. Phytoplankton are marine plants (smaller yet than the copepods), suspended in the water. People don't usually think of copepods as being capable of eating bacteria, because the bacteria are too small to catch. The purpose of this experiment is to test whether certain copepods in the Duwamish River Estuary can feed on bacteria that cling to particles. This experiment will compare the feeding rates of the copepods in water with particle-attached bacteria to feeding rates in filtered water, which only contains free-living bacteria. The potential for copepods to consume bacteria attached to particles has important implications for both trophic ecology and pollution effects in estuaries.
The purpose of this experiment is to test the hypothesis that the estuarine, planktonic copepod, Eurytemora americana, can feed at appreciable rates on suspended particle-attached bacteria, but not on free-living bacteria. Grazing rates will be determined by measuring uptake of the radioactive label, 3H thymidine, into both E. americana and bacteria in short incubation experiments. Copepods, followed by 3H thymidine, will be released into a suspension of bacteria. After one hour, the amount of isotope in copepods and bacteria will be measured. This measurement, coupled with epifluorescent estimates of bacteria per volume, permits the calculation of the grazing rates by the copepods on the bacterial populations. Grazing on free-living versus particle-attached bacteria will be measured using both a "natural" bacterial assemblage and an assemblage containing only free-living bacteria. The potential for copepods to consume bacteria attached to particles has important implications for both trophic ecology of plankton and for pollution effects in estuaries.
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In 1974, a computer model was written by Fischer on the Salt-Wedge reach of the Duwamish River Estuary. In 1975, Coliform and pH models were added to Fischer's model by W.L Haushild and Edmund A. Prych. Since this computer model was written in the days of punch cards, some revisions need to be done. I intend to update this computer model by making it run without punch cards. By doing this, I can make the computer program more efficient. I also intend to add a numerical study of toxicant fate and transport to this model. After all this is done, I hope that this model will be helpful to people studying the Duwamish River Estuary or other salt-wedge type estuaries.
A Numerical Model of the Salt-Wedge reach of the Duwamish River Estuary was written by Fischer in 1974 in the FORTRAN IV computer language and compiled on a FORTRAN H compiler off a punch card system. In 1975, W.L. Haushild and Edmund A. Prych added to this computer model in the original computer language and punch card system. My goal is to take the latest model and update it to the technology of today. I am going to rid the program of punch cards and continue to use the Fortran IV language but with a FORTRAN 77 compiler. I shall also add a toxicant study in which I shall use some of the existing subroutines in the computer model to study the fate and transport of a toxicant in the salt-wedge of the Duwamish Estuary. In order to make the model more specific to the estuary, I plan to adjust the input coefficients and make them constants in the program. This should improve the accuracy and efficiency of the program, for there will be less input information to read and process. Once this completed model is working in the original language, then I shall attempt to translate the code into the C++ language and possible make it a graphics simulation instead of just number outputs. This translation of code is dependent upon the time remaining to complete the project.
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Near Seattle, Washington, water from the murky Duwamish River spreads out over Elliott Bay carrying lots of particles with it. For some of the zooplankton species in the bay, the particles from the river may be a food source. For others, the particles might physically interfere with filters designed to capture other types of food. The purpose of this study is to find out which types of zooplankton like the particles and which ones do not. In Elliott Bay, zooplankton will be collected with a net at five points along a line that is known to span a large range of particle concentrations. The animals will be identified and counted, and their abundances will be compared to particle sizes and concentrations at the different collection sites.
The ecological role of river-derived suspended particulate matter (SPM) in the lives of several zooplankton species will be indirectly examined by way of this field study based in Elliott Bay, Washington. Zooplankton will be collected by vertical closing net tows at five stations arranged along a transect through the Duwamish River plume. At each station, a depth profile of salinity, temperature, turbidity, and fluorescence will be constructed using a CTD, transmissometer, and fluorometer. Water samples and two replicate closing net samples will then be taken from each of two depth ranges within the upper 15 meters of the water column. The lower margin of the plume, as determined from the depth profiles, will separate the two depth ranges. Sampling will take place on April 3 and 5, 1996, using the research vessel Clifford A. Barnes.
Zooplankton will be identified and counted visually under a dissecting microscope. Particle size distributions of SPM in water samples will be determined using a Coulter Counter. Water samples will also be passed through filters which will be weighed in order to obtain SPM concentrations in grams per liter. For each zooplankton species, animal abundances will be statistically compared to particle concentrations and size distributions.
The ubiquitous Larvacean species Oikopleura dioica will be of particular interest in this study because the animal's filter-feeding apparatus may clog in the presence of concentrated SPM.
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A former study indicates that the distribution of ammonia that is dissolved in the waters of the Duwamish River Estuary is not determined solely by the mixing of these waters. My project is designed to determine the influence (if one exists) that bacterial populations have on this distribution. While anchored in the river, I will take water samples from three depths every two hours. From these samples, I will measure bacterial abundance and rate of growth, ammonia concentration, salinity (the amount of salt in the water), temperature, and chlorophyll (to estimate the influence of photosynthesis). Furthermore, bacteria will be divided into two categories: free-floating and particle-attached. If relatively low levels of ammonia correspond to areas of high bacterial uptake (or high levels in areas of low uptake), then the notion of a strong bacterial influence is supported.
River estuaries are often associated with urban centers, and as a result, constitute a major anthropogenic influence on the oceans. For this reason, it is important to quantify the influence of anthropogenic inputs on the biology of estuarine systems. The Duwamish River Estuary is an area of industry, shipping, and rain/sewage-water discharge in Seattle, WA. In a previous study, the distribution of NH4 appeared to be governed by processes other than the physical circulation of the estuary alone. In order more fully to understand the ammonia distribution as affected by circulation, human inputs, and biology, I propose to sample in and above the salt wedge as it oscillates through its tidal cycle. The objective is to determine if the NH4 distribution is governed by the bacterial population in the estuary. If sinks of ammonia occur in areas of high bacterial production (or peaks in areas of low production), the notion of significant influence from bacteria is supported. If this correlation is not observed, relationships between ammonia and tide-induced mixing (ammonia from sediments) or human inputs from sewage discharges will be sought. Parameters to be analyzed are: nutrients, bacterial concentration and production (free-floating and particle-attached), salinity, and chlorophyll. I assume that the particle-attached bacteria will have higher production rates; thus my distinguishing between free-floating and particle-attached bacteria may then clarify the relationship between dissolved NH4 and bacteria.
