Transport of Gas and Solutes in Permeable Estuarine Sediments
2008
Huettel, Markus
The long-term goals of this project are to 1) quantify gas bubbles and their composition in shallow nearshore marine sand and 2) to assess the role of gas bubbles in shallow sandy coastal sediment for the transport of solutes through the sand and sediment-water exchange of matter. Due to their compressibility, gas bubbles embedded in shallow water sediments cause interstitial water oscillations under passing surface gravity waves, and these oscillations provide a mechanism for enhanced solute dispersion and flux. 1) To detect gas bubbles and in coastal and estuarine sand deposits and to assess temporal and spatial distribution of sedimentary bubbles in sublittoral beds including sands inhabited by microphytobenthos and seagrass. 2) To quantify the size range and composition of the gas bubbles in the sediment and the overlying water. 3) To determine the volume change and migration velocities of interstitial bubbles and the links to pressure oscillations 4) To assess dispersion and transport of solutes caused by bubble volume change and migration under different pressure conditions. Measurement of gas release volumes from the sediments using benthic chambers and gas analysis. Determination of gas composition. Measurement of gas bubble dimensions and distribution. Mapping of the spatial and temporal distribution of high sedimentary photosynthetic production and oxygen supersaturation and depletion as potential sites for free gas development. Determination of the rate of gas bubble release from the sediment through quantification of noble gas depletion in the pore water. Determination of gas content, distribution and migration in the surface sediment. Measurement of solute transport caused by bubble compression and migration.
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