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...
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...
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...
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...
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...
As climate change contributes to larger and more severe wildfires in California, areas of fire refugia – considered unburned and low-severity burn patches – are playing an increasingly important role in sustaining ecosystem resilience, maintaining biodiversity, and supporting post-disturbance recovery. At the same time, climate refugia – which are areas...
Non-toxic species of desiccated blue-green algae, or cyanobacteria, may offer potential for use as a fertilizer on irrigated crops. Here, the non-toxic cyanobacteria species Aphanizomenon flos-aquae (AFA), collected from Upper Klamath Lake, Oregon, was evaluated for use as a biofertilizer in a controlled experiment on Swiss chard “Bright Lights” (Beta...
The flow of multiple immiscible fluids within a porous medium controls many natural and engineered systems in the environment including: geologic CO2 sequestration, enhanced oil recovery from underground reservoirs, and contaminant remediation of groundwater. The need to understand how fluids are transported and distributed in these processes is important for...
The system in this thesis uses multiple Intel iSBC86/12A cards
connected to the Intel Multibus. The system was written using the Intel
language PLM86. The final result is a low level debug tool that
provides the user with the following capabilities: examine/change
memory, examine/change processor registers, load a user written...