This thesis investigates the influence of early diagenesis on trace metal and
molybdenum isotope behavior in marine and lacustrine environments. Chapter one is a
synthesis of previous research in all the marine environments investigated, providing an
essential geochemical context for interpreting the observed behavior of Mo in these settings.
Chapter...
Sediments of the central Chile margin record changes in ocean circulation and
continental erosion associated with large–scale climate change. Here Antarctic–
influenced Southern Ocean currents flow equatorward, forming a link between the high–
and low–latitude oceans. Part of this link, Antarctic Intermediate Water, is an important
conduit that ventilates South...
Ocean circulation is an important component in Earth's climate system. Predicting future climate and circulation changes requires an improved understanding of the past relationship between climate and ocean currents. The neodymium isotope composition (εNd) of water masses is frequently used as a quasi-conservative tracer to reconstruct ocean circulation. The current...
Large barite (BaSO4) structures mark cold seeps in the southern San Clemente Basin. Barium flux to San Clemente sediments is two to three times greater than fluxes measured in surrounding California Borderland basins. Analyses of sediment trap material, water column samples, sediments and pore water indicate that expected bariumbearing mineral...
The exchange of waters between the Pacific and the Southern Oceans occurs along the eastern boundary of the South Pacific. Because water masses of the Antarctic provide a connection among the world's ocean basins, these water masses maintain the ability to influence changes in ocean circulation and climate (Lynch-Stieglitz et...
This study is composed of two parts. Section I deals with
developed moorages and marinas--where they are; what services are
offered in each, and how well the existing supply of permanent moorages
serves the boating public. Section II examines the need for temporary
'harbors of refuge' in the area, what...
We present concentrations of germanium and silicon in sediment pore waters, basaltic formation fluids,
and bulk sediment from three ridge flank hydrothermal systems (RFHS). Basaltic formation fluids from
warm (>30°C) RFHS have much higher Ge concentrations and Ge:Si molar ratios than overlying sediment
pore waters, requiring seawater-basalt reactions to dominate...
Tillamook Bay is the second largest estuary on the Oregon coast, and concerns have been raised whether human induced impacts have been responsible for the perceived increase in sedimentation rates during the past century. Major land-use practices within the five watersheds of the Bay include logging, forest fires, the construction...
Subsurface hydrothermal activity dominates the heat and salt budgets of the deep water column in Crater Lake, Oregon. From a time series of conductivity-temperature-depth data and data from a thermistor chain mooring, we estimate that the net hydrothermal heat flow is ~1 W m⁻² and the corresponding salt flux is...
The investigation described in this project will test the hypothesis that fluxes of carbon, barium, manganese, iron and uranium associated with fluid seepage at the San Clemente fracture zone significantly affect the geochemical budgets for these elements, and ultimately result in anomalously high benthic fluxes throughout the San Clemente basin.
A meaningful application of Mo as a paleo-redox proxy requires an understanding of Mo cycling in modern reducing environments. Stagnant euxinic basins such as the Black Sea are generally regarded as model systems for understanding euxinic systems during early Earth history. However, drawing direct parallels between the Black Sea and...
As a result of the past three years of field studies and our interpretation of these and other data from the literature, we conclude that there are inputs of hydrothermal fluids into the bottom of Crater Lake. The dissolved materials associated with these thermally and chemically enriched fluids, coupled with...
This dissertation works towards determining the mechanisms driving the Mo isotopic composition of soils, and how these signals may be used to refine the use of Mo as a proxy of biogeochemical processes. The first step towards quantifying Mo fractionation in soils is to determine the mechanisms controlling Mo accumulation,...
A benthic microbial fuel cell (BMFC) is an electrochemical device that
generates current from the redox gradient at the sediment-water interface. Early
prototypes had anodes buried in anoxic sediments and cathodes in overlying water.
The BMFCs described in this dissertation are based on a chamber design that enables
the use...
This thesis presents the results of a formal evaluation of a new AOGCM, GENMOM, demonstrating its ability to simulate present-day climate and ENSO dynamics. The model is applied to simulate climate for the Last Glacial Maximum, deglacial, and Holocene time periods. The model output is evaluated against the best available...
Benthic incubation chambers have been deployed in a variety of geochemical environments that provide a comprehensive geochemical framework from which to address issues related to Ba geochemistry and the use of Ba as a paleoproxy. First order budgets for barium show that in the equatorial Pacific, present rates of Ba...
Flux estimates show that upward mixing of the deep-water nitrate pool accounts for more than 85% of the total new nitrogen input to the euphotic zone of Crater Lake. Because measured primary productivity (360 mg C m-2 d-1) is 10–30 times higher than a level supported solely by the input...
We present molybdenum isotope and concentration data from 14 sites in the eastern Pacific from the
central California to the Peru margin. The environments studied have been chosen to represent a broad
range in oxidation-reduction (redox) potential, which provide a framework for the behavior of this redox-sensitive
element. Manganese-rich hemipelagic...
We present a new estimate for the crustal phosphorous sink that results from reactions among seawater, basalt, and sediment blanketing low temperature mid-ocean ridge flank hydrothermal systems. New estimates for global hydrothermal power output, sediment thickness, and the dissolved phosphate concentrations in basement formation fluids indicate that fluid flow through...
Diatom remains indicate the oceanic Ge/Si ratio (μmol/mol) has varied temporally, ranging from Miocene values of 0.9 to Last Glacial Maximum (LGM) values of 0.55, with the present value of 0.69. These ratios lie between those for the primary sources for these elements: continental weathering (Ge/Si = 0.5) and hydrothermal...
The data presented in this report demonstrate significant improvements
in the ability to constrain trace element and Sr isotopic
concentrations in sediments overlying ridge-flank hydrothermal
systems. Improved sampling methods orchestrated by the Integrated
Ocean Drilling Program (i.e., advanced piston coring and
anoxic sample processing) enabled the collection of reactive pore...
Active inputs of thermally and chemically enriched fluids at the bottom of Crater Lake create small vertical and horizontal heterogeneities in the deep-lake temperature and salt distribution. Using an internally recording CTD and a precise definition for salinity as a function of in situ conductivity and temperature, we assess the...
On average, the water column of Lake Superior is undersaturated with respect to dissolved oxygen and supersaturated with respect to carbon dioxide during the summer-stratified period. On the basis of temporal changes in water column dissolved oxygen, we calculate rates of oxygen consumption that range from 0.19 to 0.75 mmol...
The ability to reconstruct past ocean currents is essential for determining ocean circulation’s role in global heat transport and climate change. Our understanding of the relationship between circulation and climate in the past allows us to predict the impact of future climate-driven circulation changes. One proposed tracer of past ocean...
We determined pore fluid rare earth element (REE) concentrations in near-surface sediments retrieved from the continental margin off Oregon and California (USA). These sites represent shelf-to-slope settings, which lie above, within, and below the oxygen minimum zone of the Northeast Pacific. The sediments are characterized by varying degrees of net...
Because ocean circulation impacts global heat transport, understanding the relationship between deep ocean circulation and climate is important for predicting the ocean's role in climate change. A common approach to reconstruct ocean circulation patterns employs the neodymium isotope compositions of authigenic phases recovered from marine sediments. In this approach, mild...
The rare earth elements (REEs) have been established as powerful tracers for a range of physiochemical processes occurring in the natural environment. They also hold significant economic importance as many technological advancements are reliant upon the REEs for their unique magnetic, luminescent, and electrochemical characteristics. In sedimentary settings, understanding the...
Small temporal and spatial variations in the distribution of dissolved oxygen in Crater Lake, Oregon, are used to estimate the mean age of the lake’s deep water, the flux of labile organic carbon to the deep lake, and the influence of hydrothermal activity on the concentration of dissolved oxygen within...
Isotopic analyses of dissolved molybdenum are presented for sediment pore waters from a reducing
sedimentary basin and for fluids from a low-temperature ridge flank hydrothermal system. δ⁹⁸/⁹⁵Mo in
these fluids range from 0.8 to 3.5%₀ (relative to a laboratory standard), demonstrating that marine
sedimentary reactions significantly fractionate Mo isotopes. Within...
We present evidence for pore water flow through the sediment of Crater Lake, Oregon based on systematic variations in pore water chemical compositions and thermal gradients. Pore water was extracted from sediment by centrifugation and diffusive exchange using a gravity corer deployed from a surface vessel and a box corer...
We examined the characteristics of biological patches at four different locations to assess the relationship of patch vertical scale, amplitude, and persistence. In contrast to patches of larger animals, we found that the majority of coherent aggregations of plankton at each site were vertically compressed, with most smaller than 5m...
This thesis investigates the behavior of major inorganic nutrients (P, N, Si), trace metals (Mn, Fe), and alkaline-earth metals (Ba) within Tillamook Bay over seasonal cycles and under a range of river discharge conditions from October 1997 through December 1999. Located in the Pacific Northwest region, Tillamook Bay is an...
The objective of this study was to compare two techniques for estimating benthic fluxes of nutrients (nitrate, phosphate, and silicic acid) and Ge/Si flux ratios. In situ flux chambers were deployed, and cores were collected and incubated at 9 sites along the California margin in July 2001. Both techniques were...
The isotopic composition of the dissolved inorganic carbon (DIC) collected at sites of active methane discharge on Hydrate Ridge, Oregon, reveals anaerobic methane oxidation mediated by bacteria, with δ13CDIC reaching values as low as –48‰ in the upper 4 cm of the sediment. In spite of the high sulfide levels...
Benthic chamber measurements of the reactants and products involved with biogenic matter diagenesis (oxygen, ammonium, nitrate, silicate, phosphate, TCO₂, alkalinity) were used to define fluxes of these solutes into and out of the sediments off southern and central California. Onshore to offshore transects indicate many similarities in benthic fluxes between...
Geophysical and biogeochemical processes associated with fluid venting from active and passive continental margins will receive significant scientific and economic attention
into the next century and are of major societal relevance. An important unknown among these interrelated processes is the role played by methane gas hydrates, at and below the...
A massive release of methane on the Cascadia Hydrate Ridge was documented
during a ROPOS program in August 1998, consistent with previously reported
observations in 1996. An extensive survey of the seafloor revealed that the
seeps lie within a narrow band trending 109 degrees. This feature parallels larger
mounds imaged...
A study was conducted to determine the heat transfer characteristics
of pin finned heat sinks in natural convection. Three pin
diameters were studied: 0.238 cm, 0.318 cm and 0.396 cm. The pins
were attached to the base in two arrangements, triangular and
rectangular, forming a horizontal array. Pin spacing was...
Cores taken from the ridge areas of the Gorda-Juan de Fuca
plate have a sedimentation rate that is appropriate for the study of
late Quaternary stratigraphy. An analysis of the clay and silt
mineralogy of the cores using X-ray diffraction methods and by
noting changes in the foraminiferan-radiolarian abundances in...
More Americans are participating in sport every year
and several organizations have made it their mission to
provide the opportunity for organized sport participation.
College and University intramural departments are one of
those organizations. They provide participation
opportunities on nearly every college campus. The review of
literature identifies the sociological...
Monocrotaline (MCT) is a member of a class of naturally occurring
phytotoxins known as pyrrolizidine alkaloids (PAs). Exposure to PAs can result
in liver and cardiopulmonary lesions as well as lymphoid organ atrophy. In the
present study C57BI/6 (B6) mice received MCT (0-150 mg/kg/day, po) for 14
days. Overt toxicity...
In the summer of 2001 the Oregon Coast Aquarium opened a new exhibit on sharks entitled, "Great White Mystery: What Happened to Surfer Bob?" For the purposes of this study, a survey was designed to determine whether visitors to the new exhibit learned factual information or left with changed attitudes...
The mycosporins, formerly called P310's are secondary metabolites
of fungi closely associated with fungal reproductive processes that
require light. The structurally related iminomycosporins are found in
marine plants and animals and may also have functions related to
light. In this study, approaches toward the asymmetric synthesis of
the mycosporins are...
In vivo research following ingesting of commercially available
Lactobacillus tablets, which contain about 2X10⁶ cfu/tablet of
Lactobacillus acidophilus and Lactobacillus bulgaricus cells in a dose
of four tablets daily, showed serum lipoprotein concentrations did not
change significantly. In order to increase the number of viable
Lactobacillus bacteria after challenging in...
Jets in crossflow are used in a wide range of engineering applications and have been studied for more than 60 years. The transversal penetration and structure of a jet placed in a crossflow is known to be strongly three-dimensional. It is believed that, by using a pulsed jet inclined in...
A personal view of the 50 years of broadcasting - radio and ETV - that we call KOAC, Corvallis. Service to people of Oregon from 1922 through 1972 with program philosophies, historical evolution of facilities - and the people who kept is all happening ......
To investigate the responses of healthy adult women to two
levels of vitamin B-6, a seven week two-part experiment was conducted
with five young adults and eight middle-aged subjects. During the
four unsupplemented weeks, dietary vitamin B-6 was 2.3-2.4 mg/day.
In the final three weeks, the same diet was supplemented...