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USGS and Florida State University Scientists Collaborate on Submarine-Ground-Water-Discharge Study in the Northern Gulf of Mexico
During the week of January 30, 2006, scientists from the U.S. Geological Survey (USGS) joined scientists from Florida State University (FSU) to begin an investigation of the links between submarine ground-water discharge and climatic (seasonal) change. Submarine ground-water dischargethe flow of ground water directly into seawatercan strongly influence coastal ecosystems, with the potential for harmful effects if the ground water contains high levels of contaminants or excess nutrients. For the recent study, part of a multiyear project funded by the National Science Foundation, USGS scientist Peter Swarzenski and his SGD team members Chris Reich (USGS) and Jason Greenwood (ETI Professionals, Inc.) traveled from their office in St. Petersburg, Fla., to the FSU Marine Laboratory at Turkey Bayou on Florida's northwest coast (south of Tallahassee). There they worked with FSU professor of oceanography Bill Burnett and his team of students (Natasha Dimova, Benjamin Mwashote, Rick Peterson, and Isaac Santos) at a study site near the lab. USGS participation in the study was twofold:
Preliminary results suggest that during this dry-season, 5-day experiment, fluctuations in the submarine-ground-water-discharge rate as measured by one electromagnetic seepage meter appeared to respond almost predictably to water-level changes, with discharge increasing during times of low water levels (low tides). In the coming months, additional analyses, including time-series measurements of 222Rn, 223Ra, 224Ra, 226Ra, 228Ra, and possibly thoron (a radioactive isotope of radon, 220Rn, with a half-life of just 55 seconds!), will complement the resistivity and seepage-meter work. These isotopes are much more abundant in ground water than in surface water and therefore serve as effective tracers of ground-water discharge. An advantage of geochemical tracers over seepage meters is that they provide a regional-scale estimate of submarine ground-water discharge, rather than the extremely local coverage provided by seepage meters. For more information about submarine ground-water discharge, see "Submarine Ground-Water Discharge and Its Influence on Coastal Processes and Ecosystems," in Sound Waves, June 2004; "Submarine Groundwater Discharge: An Unseen Yet Potentially Important Coastal Phenomenon"; and "Submarine Ground-Water Discharge".
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in this issue:
Submarine Groundwater Discharge Study USGS Assists in Search for Airplane Wreckage Methane Hydrate off Southern California Coast Open House at FISC St. Petersburg Falmouth Science Teachers visit USGS Woods Hole Sea-Floor-Mapping Systems Described on New Web Pages Wetland Ecologist Named Fulbright Senior Specialist Multiple Award Winner in USGS Photography Contest |