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Tidal wetland fluxes of dissolved organic carbon and sediment at Browns Island, California: initial evaluation

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Abstract

Carbon and sediment fluxes from tidal wetlands are of increasing concern in the Sacramento-San Joaquin River Delta (Delta), because of drinking water issues and habitat restoration efforts. Certain forms of dissolved organic carbon (DOC) react with disinfecting chemicals used to treat drinking water, to form disinfection byproducts (DBPs), some of which are potential carcinogens. The contribution of DBP precursors by tidal wetlands is unknown. Sediment transport to and from tidal wetlands determines the potential for marsh accretion, thereby affecting habitat formation.
Water, carbon, and sediment flux were measured in the main channel of Browns Island, a tidal wetland located at the confluence of Suisun Bay and the Delta. In-situ instrumentation were deployed between May 3 and May 21, 2002. Water flux was measured using acoustic Doppler current profilers and the index-velocity method. DOC concentrations were measured using calibrated ultraviolet absorbance and fluorescence instruments. Suspended-sediment concentrations were measured using a calibrated nephelometric turbidity sensor. 
Tidally averaged water flux through the channel was dependent on water surface elevations in Suisun Bay. Strong westerly winds resulted in higher water surface elevations in the area east of Browns Island, causing seaward flow, while subsiding winds reversed this effect. Peak ebb flow transported 36% more water than peak flood flow, indicating an ebb-dominant system. DOC concentrations were affected strongly by porewater drainage from the banks of the channel. Peak DOC concentrations were observed during slack after ebb, when the most porewater drained into the channel. Suspended-sediment concentrations were controlled by tidal currents that mobilized sediment from the channel bed, and stronger tides mobilized more sediment than the weaker tides. Sediment was transported mainly to the island during the 2-week monitoring period, though short periods of export occurred during the spring tide. Future deployments will characterize the seasonal variability of these fluxes.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Tidal wetland fluxes of dissolved organic carbon and sediment at Browns Island, California: initial evaluation
Year Published 2003
Language English
Contributing office(s) Pacific Regional Director's Office, San Francisco Bay-Delta
Description 1 p.
Larger Work Type Conference Paper
Larger Work Title Proceedings of the 2003 CALFED science conference
First page 208
Last page 208
Conference Title 2003 CALFED science conference
Conference Location Sacramento, California
Conference Date January 14-16, 2003
Country United States
State California
Other Geospatial Browns Island
Online Only (Y/N) N
Additional Online Files (Y/N) N