HR: 16:00h
AN: H24A-01 INVITED     [Abstracts]
TI: Comparing Advective and Diffusive Transport in Marine Sediments
AU: * Huettel, M
EM: mhuettel@ocean.fsu.edu
AF: Florida State University, Department of Oceanography, 900 West Call Street, Tallahassee, FL 32306-4320 United States
AB: In this contribution we contrast diffusive and advective solute transport in marine sediments. The microbial decomposition of organic matter in aquatic deposits is controlled by the transport processes that carry degradable substances and metabolites into and out of the bed. In most marine deposits this transport is caused mainly by molecular diffusion and bioturbation. In sandy sediments that dominate the shallow shelf, the permeability of the bed permits the flow of water through the upper layers of the sediment that is driven by the interaction of sediment topography and boundary layer currents. In-situ measurements show that these advective pore water flows can pump several hundred liters sea water per m2 and day through the upper layer of a permeable sand bed and thus, can cause exchange of solutes that exceeds that driven by diffusion by several orders of magnitude. The fundamentally different transport characteristics of advective pore water flows produce distinct differences between the biogeochemical zonation of permeable and cohesive beds. The role of the filtering shallow shelf sands in the marine cycles of matter still is largely unknown despite the fact that permeable shelf sediments may intercept or remove land-derived nutrients along the land-to-sea continuum, thereby regulating coastal primary production.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1050 Marine geochemistry (4835, 4850)
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting