Bratton, J. ., U.S. Geological Survey, Woods Hole, USA, jbratton@usgs.gov
Crusius, J. ., U.S. Geological Survey, Woods Hole, USA,
Kroeger, K. ., U.S. Geological Survey, Woods Hole, USA,
Böhlke, J. K., U.S. Geological Survey, Reston, USA,
Bowen, J. ., Princeton University, , USA,
Cross, V. ., U.S. Geological Survey, Woods Hole, USA,
Worley, C. ., U.S. Geological Survey, Woods Hole, USA,
Erban, L. ., ETI Professionals, Inc., Woods Hole, USA,
Green, A. ., U.S. Geological Survey, Woods Hole, USA,
Baldwin, S. ., ETI Professionals, Inc., Woods Hole, USA,

STEEP AGE AND SALINITY GRADIENTS IN SUBMARINE GROUNDWATER MEASURED IN A SMALL CHESAPEAKE BAY TRIBUTARY

Submarine groundwater discharge (SGD) into Maryland’s Corsica River estuary was investigated as part of a larger study to determine the importance of nutrient delivery to Chesapeake Bay via this pathway. Experiments performed included continuous resistivity profiling (CRP), piezometer sampling, seepage meter measurements, and collection of a radon tracer time series. Results from a detailed study site show a shallow plume of terrestrial groundwater (salinity <1.5) located within 2 m of the estuary floor and extending >17 m offshore, which is overlain by a thin and variable brackish zone. Deeper low-salinity groundwater extends >200 m offshore based on CRP data. Groundwater and surface water were sampled for analysis of nutrients, stable and radioisotopes, age tracers, and microbes. Tritium data indicate that young groundwater discharges near shore, but that the age of groundwater increases with depth and distance offshore. Discharge rates were highly variable and strongly influenced by astronomical and wind-driven tides. Better understanding of the distributions of age and chemical composition in groundwater discharge areas such as this could lead to improved models and mitigation strategies for estuarine nutrient over-enrichment.

http://soundwaves.usgs.gov/200

Poster presentation

Presentation is given by student: No
Session #:089
Date: 03-06-2008
Time: 17:30 - 19:30