General
For a brief description of my research interests, see Profile. For a full list of publications, please refer to my CV. For highlights of current research, click here.
My Laboratories
My labs in Port Aransas consist of a wet chemical lab, an instrumentation lab, and a semi-"clean lab" for preparing samples for analysis of trace elements.
The main piece of equipment in the instrumentation lab is a Canberra High Purity Germanium Well Detector:
We use this gamma detector for measuring naturally occuring radionuclides, such as Th-234, Pb-210, Ra-224, Ra-226, and Ra-228. It is being used for both the Indian Ocean plume work and the groundwater work, described below.
The detector is surrounded by 6 inches of low background lead. This shields the detector from background radiation, which is much higher than the amounts we are trying to measure.
The shield weighs 3600 pounds. Getting it up to the lab was no easy feat!
September, 2000
The "clean lab" is not a very high technology lab with filtered air. Instead,
it is a relatively isolated space whose main purpose is to make you remember to "think
cleanly" when working with samples. There is almost no metal in the lab. It
has a new PVC fume hood for acid digestions, a laminar flow bench for working in
a clean environment, and a water purification system:
Finally, I also have a lab in Austin, where I co-own two ICP Mass Spectrometers,
a Micromass Platform and a multicollector, Micromass IsoProbe. See the Isotope
Geochemistry pages in the UT Dept. of Geological Sciences, and watch this space
for photos of the IsoProbe installation!
Current Projects
Hydrothermal vents in the Arctic Ocean
Read about our discovery of the first hydrothermal vents on the Gakkel Ridge, published in Nature on January 16, 3003:
Download the Nature paper and the Supplementary Information. (These are available as PDF files. You will need a free PDF reader to view them.)
Press releases and news coverage:
UT
Press Release
Nature highlight
United Press
International story
Science News (subscription
needed to view article)
The Washington Post, January
27
National Geographic News
Geotimes, January 24
NOAA home page story
These discoveries were made during a 9 week expedition ("AMORE") to the Arctic Ocean in 2001 aboard the icebreaker USCGC Healy. The expedition was led by Peter Michael of the University of Tulsa. I was invited along to look for evidence of hydrothermal vents. Many people didn't expect us to find anything, because the Gakkel Ridge is the slowest spreading mid-ocean ridge on Earth. Instead, we can pinpoint 9 different vent sites to specific geological features, and know there are at least 3 other sites in the 1100 kilometer stretch of the Gakkel Ridge that we surveyed.
Map of the Arctic Ocean floor, indicating the Gakkel Ridge, the Healy's cruise track (black dotted line), and our nine vent sites (yellow stars): Click here for a higher-resolution (300 dpi) version. Map by Hedy Edmonds, using GMT software and bathymetric data from the International Bathymetric Chart of the Arctic Ocean.
AMORE Expedition Web Sites 
- The "Arctic Volcanoes" web site at Columbia Earthscape (click on the link to "The Techniques" for my page on hydrothermal plumes)
- Michele Adams' Teachers Experiencing the Arctic web site
- The site maintained by our German partners on Polarstern
Post-cruise sites
- Linda Kuhnz's page at Moss Landing Marine Labs
Early post-cruise news coverage (non-exhaustive)
Groundwater discharge to the bays of South Texas
Tracy Villareal and I have a year of funding from the Texas Water Development Board for a project entitled "Submarine Groundwater and Nutrient Fluxes in a Semi-arid Environment."
Here is the project summary:
This proposal involves a one-year study to quantify water and nutrient fluxes via submarine groundwater discharge (SGWD) to two bays on the South Texas coast: Upper Laguna Madre and Corpus Christi Bay. We will use measurements of naturally occurring radium isotopes (Ra-224, Ra-228, and Ra-226) to establish the flux of groundwater into these bays. We will then use these calculated water fluxes and measurements of nutrients (N, P, and Si) to determine the fluxes of nutrients to the bays via SGWD and investigate the impact of these fluxes on nutrient distributions and ecosystem health. Quantifying groundwater discharge and associated chemical fluxes today is critical to effective coastal management and to predicting the impacts of potential future changes in aquifer use or the results of aquifer contamination.
Illustration of the process of submarine groundwater discharge (SGWD) to the coastal zone. A hydraulic head on the coastal aquifer will allow discharge of groundwater offshore in the absence of confining layers of impermeable rock (upper SGWD arrow). The presence of a confining layer may block flow, or force it further offshore into deeper water (not shown). If dredged channels penetrate such a confining layer, SGWD may be initiated (lower SGWD arrow). Runoff and mixing arrows indicate other sources of water to the coastal region. Studies of SGWD must account for the input of the tracer of interest by these other routes as well.
Chip Breier, a second year Ph.D. student, is working on this project in my lab.
Hydrothermal Plume Geochemistry in the Indian Ocean
With funding from the National Science Foundation's RIDGE Program, I participated in a British research cruise in 2001 to study hydrothermal plumes in the central Indian Ocean, just north of the Rodriguez Triple Junction.
Thorium-230 and Protactinium-231 in the Atlantic Ocean
This is a project I am still working on with Brad Moran, my postdoctoral supervisor at the University of Rhode Island's Graduate School of Oceanography.
