HR: 0800h
AN: H21B-1009    [Abstracts]
TI: Using Geophysical Methods to Detect Submarine Groundwater Discharge in Sarasota Bay, FL
AU: * Harrison, A S
EM: asharri2@mail.usf.edu
AF: University of South Florida, Dept. of Geology 4202 East Fowler Ave, Tampa, FL 33620 United States
AU: Kruse, S
EM: skruse@chuma1.cas.usf.edu
AF: University of South Florida, Dept. of Geology 4202 East Fowler Ave, Tampa, FL 33620 United States
AU: Murray, M
EM: mmurray@ocean.fsu.edu
AF: Florida State University, Dept. of Oceanography 0102 OSB West Call St., Tallahassee, FL 32306 United States
AU: Chanton, J
EM: chanton@ocean.fsu.edu
AF: Florida State University, Dept. of Oceanography 0102 OSB West Call St., Tallahassee, FL 32306 United States
AU: Burnett, B
EM: wburnette@mailer.fsu.edu
AF: Florida State University, Dept. of Oceanography 0102 OSB West Call St., Tallahassee, FL 32306 United States
AU: Sandberg, S
EM: stewart@geophysicalsolutions.com
AF: Geophysical Solutions, Geophysical Soulutions, Inc., P.O. Box 50248, Albuquerque, NM 87181 United States
AB: Submarine groundwater discharge (SGD) can be an important pathway for nutrients entering coastal systems. However SGD flow paths can be difficult to identify and flow volumes difficult to quantify. This study assesses whether geophysical techniques are potentially cost effective methods for detecting the presence or lack of SGD within Sarasota Bay, Florida. In this area, a rapid increase in urbanization has led to increased nitrogen loading into the bay, with some 10% of this loading attributed to SGD. In this study we compare the results of both marine resistivity and marine electromagnetic surveys against geochemical techniques (radon and methane tracers) as well as the conventional method of SGD detection, seepage meters. Marine resistivity surveys offer access to deeper and more open waters, while the marine electromagnetic technique is applied in very shallow areas and those where a long streamer cannot be towed. Preliminary results show that there appears to be a correlation between high seepage as measured by tracer studies and a decrease in the seafloor conductivity measured with geophysical methods. Along with changes in seafloor conductivity, there appear to be small but detectable changes in the surface water temperature gradient in close proximity to SGD discharge points.
DE: 4546 Nearshore processes
DE: 1829 Groundwater hydrology
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting