Schwartz, M. C. University of Delaware - College of Marine Studies, schwm@udel.edu
Sharp, J. C. University of Delaware - College of Marine Studies, jsharp@udel.edu
Church, T. University of Delaware - College of Marine Studies, tchurch@udel.edu
Hussain, N. University of Delaware - College of Marine Studies, najid@udel.edu

 
IDENTIFICATION AND BIOGEOCHEMICAL ASSESSMENT OF A GROUNDWATER DISCHARGE ZONE IN THE DELAWARE ESTUARY
 
Submarine groundwater discharge (SGD) may actively influence coastal and estuarine biogeochemistry by transporting groundwater and associated dissolved chemicals from terrestrial aquifers. An apparent zone of groundwater discharge to the Delaware Estuary has been identified through the assessment of Excess Rn, a natural groundwater tracer. An Excess Rn Maximum (ERM) was identified with estuarine Excess Rn between 1.6 and 2.7 dpm/L over an annual cycle. The SGD source aquifers contain groundwater with extremely high Rn (~1,000 dpm/L), the discharge of which results in the ERM, a spatially-limited geochemical feature sustained over seasonal and event variations in groundwater and surface water hydrology. The hydrologic connection between terrestrial aquifers and the Estuary may prove to be particularly important in the investigation of nutrient and contaminant transport from terrestrial aquifers to coastal and estuarine waters. Groundwater nitrate concentrations (as high as 1,000 micromolar) are much higher than in the Estuary (5-150 micromolar). Our current data reveal elevated estuarine nitrate concentrations corresponding to elevated Excess Rn, suggesting a nitrate-SGD link. Nitrate and other dissolved constituents (nutrients and contaminants) in the source aquifer may be transported to the Estuary via SGD and effect biogeochemical impacts at the ERM and other estuarine SGD zones.
 
Day: Friday, Feb. 5
Time: 11:00 - 11:15am
Location: Eldorado Hotel
 
Code: CS57FR1100E