HR: 0800h
AN: OS51C-1317    [Abstracts]
TI: Water Quality Gradients across Albemarle-Pamlico Estuarine System: Seasonal Variations and Model Applications
AU: * Lin, J
EM: jing_lin@ncsu.edu
AF: Dept. Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 United States
AU: Xie, L
EM: lian_xie@ncsu.edu
AF: Dept. Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 United States
AU: Pietrafesa, L
EM: ljpietra@ncsu.edu
AF: Dept. Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 United States
AB: The seasonal variations of water quality parameters as nitrite plus nitrate (NO23), total phosphate (PO4), Chlorophyll a and dissolved oxygen (DO) are analyzed across the Croatan-Roanoke-Albemarle-Pamlico-Core Sounds Estuarine System (CAPES). Overall, several patterns are observed: The Chowan-Roanoke-Albemarle system is generally phosphorous limiting for phytoplankton growth, while both the Tar-Pamlico and the Neuse Rivers are generally nitrogen limiting. The largest PO4 gradients exist in the upper estuary of the Albemarle Sound and the largest NO23 gradients exist in the upper estuary of the Neuse and the Tar-Pamlico Rivers. Dissolved oxygen appears to have the strongest seasonal signal among the water quality variables with highest DO values observed during winter (within the CAPES and in the nearshore area) or spring (in the continental shelf and deeper ocean) and lowest during summer. Chlorophyll a concentrations are highest during spring (within the CAPES) or winter (offshore). In contrast, the NO23 and PO4 concentrations in both the Tar-Pamlico and Neuse River Estuaries are usually higher during the second half of the year. The time differences of the peak nutrient and chlorophyll a concentrations suggest that highest algal growth rate (and hence nutrient uptake rate) occur during spring while the consumed nutrients are released to the water column through a nutrient recycling method later in the year. A coupled three-dimensional hydrodynamic water quality model is then applied to the entire system. The general model set-up and parameter derivation of the model is presented in the paper. The basic observed water quality characteristics such as the nutrient limiting pattern and the spatial gradients across the system are reproduced in the model. The model results also suggest that nutrient fluxes, generated from the diagenesis of deposited organic matters and released from the sediment bed may be an important mechanism for nutrient recycling in the region.
DE: 4834 Hypoxic environments
DE: 4842 Modeling
DE: 4845 Nutrients and nutrient cycling
DE: 4235 Estuarine processes
DE: 4255 Numerical modeling
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting