HR: 09:15h
AN: B31A-04    [Abstracts]
TI: Investigating the Biogeochemical Response of The Benthic Boundary Layer to Erosion and Deposition Events Using a 1-D Coupled Sediment Entrainment-Biogeochemistry Model
AU: * Cobb, C M
EM: cobb@nrlssc.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory, Building 1009, Stennis Space Center, MS 39529 United States
AU: Furukawa, Y
EM: yfurukawa@nrlssc.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory, Building 1009, Stennis Space Center, MS 39529 United States
AU: Keen, T R
EM: keen@nrlssc.navy.mil
AF: Naval Research Laboratory, Naval Research Laboratory, Building 1009, Stennis Space Center, MS 39529 United States
AB: The entrainment of cohesive sediments involves coupled sediment-bottom boundary layer processes forced by waves, currents and complex physical, biological, and chemical processes (e.g. consolidation, bioturbation/bioirrigation, geochemistry) that occur within the seafloor sediments. Transition metal contaminants are significantly affected by the redox environment of the surrounding sediments. Therefore, an ability to predict their transport and chemical alteration is necessary for environmental remediation. This study uses a system of coupled models to simulate the 1-D vertical entrainment of heterogeneous coastal sediments and the biogeochemistry of the benthic boundary layer sediments as an initial attempt to create such a predictive tool. An ideal case, forced only by tides and waves, is examined in order to understand the sensitivities of the sediment profiles to the wave-tide forcing and the bottom sediment biogeochemistry to erosion/deposition events generated by the sediment entrainment. In particular, the spatial and temporal changes of the redox species NH4 and SO4 in the pore water of the bottom sediments are analyzed. In addition, the sensitivity of the suspended sediment profile to changes in seafloor properties (% of cohesive sediments, grain size, erosion rate parameters) is investigated. The model is calibrated using suspended sediment concentration data collected at Hunters Point Shipyard (HPS) in San Francisco Bay, California. Realistic sea surface elevation and current velocities, generated using the 3-D baroclinic NCOM hydrodynamic model, are used by the 1-D sediment model to determine the suspended sediment profiles at two locations in the northern and southern regions of HPS. The parameters of the sediment entrainment model are then adjusted to match the measured values of suspended sediment concentration and the response of the biogeochemistry is examined over the entire month of January 2004.
DE: 4255 Numerical modeling
DE: 4804 Benthic processes/benthos
DE: 4805 Biogeochemical cycles (1615)
DE: 4851 Oxidation/reduction reactions
DE: 4863 Sedimentation
SC: Biogeosciences [B]
MN: 2005 Joint Assembly