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Groundwater-derived Nitrogen and Phosphorus Inputs to the Satilla River Estuary: Impact of coastal ecosystem health

PIs: Samantha B. Joye (Dept. of Marine Sciences, Univ. of Georgia), Carolyn D. Ruppel (Dept. of Earth and Atmospheric Sciences, Georgia Inst. of Tech.), and Williard S. Moore (Dept. of Geological Sciences, Univ. of South Carolina)

Support: Sea Grant College Program

Timeframe: 2002 - 2005

Project Objectives:

1) To compare and contrast groundwater-surface water interactions at two sites, Dover Bluff and White Oak Creek, which represent developed and relatively undeveloped endmembers;

2) To characterize the geochemical signature of groundwater, sediment pore water and surface waters within each site;

3) To estimate groundwater-derived nutrient inputs to the Satilla River estuary;

4) To evaluate the capacity for sediment denitrification to remove groundwater-derived nitrogen at the marsh-estuary interface;

5) To document the impact of groundwater-derived nutrients on primary production in tidal creek waters;

6) To complete regional (Southeastern U.S.) and international (Netherlands) comparisons to constrain the magnitude and importance of groundwater-derived nutrient inputs to coastal waters.

Progress and Findings:
We have conducted two field expeditions to the Satilla River field sites at Dover Bluff (DB) and White Oak Creek (WOC) (Jan and Aug, 2003). We conducted two 6-8 week pore water equilibration chamber incubations to obtain steady state profiles of dissolved pore water constituents (hereafter, these data are referred to as "peeper" profiles). At each site, duplicate peepers were obtained (4 peepers analyzed per trip). We conducted flow-through chamber incubations under light and dark conditions using cores from the DB site (in Jan-04). Data obtained from flow through experiments were to calculate rates of exchange (benthic fluxes) of carbon, oxygen, nutrients and dissolved gases (O2, N2 and Ar). 15N tracer experiments were also conducted during the flow through experiments to determine the fate of water column dissolved inorganic nitrogen. Wells and piezometers were sampled at the DB site in Nov and Dec of 2003 and in March and April 2004. Sample analyses are underway. Plugflow bioreactor experiments are being used to evaluate the reactivity of groundwater-derived materials and to determine the controls on sediment metabolism.

Publications in preparation:

Joye, S. B., R. Y. Lee, R. J. Wisniewski, W. P. Porubsky, N. B. Weston, I. Valiela and P. Van Cappellen (in prep). Environmental controls on denitrification and nitrous oxide production in coastal sediments.

Porubsky, W. P., N. B. Weston and S. B. Joye (in prep) Dissimilatory nitrate reduction to ammonium in near shore sediments.

Joye, S. B., W. P. Porubsky, N. B. Weston, W. S. Moore, C. Meile and C. D. Ruppel (in prep) Groundwater as a source of labile nutrients and organic materials to coastal ecosystems.

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This page was updated October 13, 2006