Advective particle transport into permeable sediments—evidence from experiments in an intertidal sandflat

Abstract

Advective transport of artificial and natural particles into permeable sediments was demonstrated in situ by field experiments in an intertidal Wadden Sea sandflat. Using dyed sediment, advective interfacial solute exchange was shown to reach down at least 1.5 cm below surface. Particle depth distributions depended on sediment permeability and particle size. Sandy sediments were found to efficiently trap particulate material. At the beginning of the local phytoplankton spring bloom, an average m 2 of coarse-grained sediment received 850-mg organic carbon per day by filtration of 14 liters of overlying water per hour. We discuss the relative importance of different transport mechanisms, and data from parallel studies on natural sediments at the same site are interpreted in close correlation to the results of the in situ experiment.Deposition and resuspension are considered a major link between water column and the sediment (van Raaphorst et al. 1998), and on the inner shelf (water depth Ͻ100 m) suspended matter concentrations in the order of 0.

Seasonality of Organic Matter Degradation Regulates Nutrient and Metal Net Fluxes in a High Energy Sandy Beach

“…So far, the impact of pore water advection on biogeochemistry and pore water constituent effluxes from permeable sediments has mostly been studied in microtidal sheltered beaches (Beck et al, ; Gonneea & Charette, ; Liu et al, ; O'Connor et al, ; Santos et al, ), tidal flat areas (Beck et al, ; Billerbeck et al, ; Gao et al, ; Huettel & Rusch, ; Marchant et al, ; Riedel et al, ), or subtidal sediments (Ahmerkamp et al, ; Marchant et al, ; Shum & Sundby, ), which are exposed to a lower wave energy level than high energy beaches. In contrast, only few studies have been conducted at wave exposed mesotidal to macrotidal sites like the French Aquitanian coast (Anschutz et al, ; Charbonnier et al, ; Charbonnier et al, ) or the beaches of Spiekeroog Island, Germany (Beck et al, ; Reckhardt et al, ; Seidel et al, ; Waska et al, ).…”

Benthic Dinitrogen Fixation Traversing the Oxygen Minimum Zone Off Mauritania (NW Africa)

“…Permeable sandy sediments were originally considered to be biogeochemically inert due to their low organic carbon content (Shum and Sundby, 1996;Boudreau et al, 2001). Yet, topography-driven advective solute transport due to pressure gradients and bottom currents has changed this view Rusch and Huettel, 2000;Janssen et al, 2005). Sandy sediments are thus often regarded as potential sites for high metabolic activity (Boudreau and Westrich, 1984;Huettel et al, 2003).…”

Intensive and extensive nitrogen loss from intertidal permeable sediments of the Wadden Sea

“…Recent studies showed that pore-water advection dominates chemical exchange at the sediment-water interface of the sandy seafloor, with advective transport exceeding the rate of molecular diffusion by several orders of magnitude (Precht and Huettel 2004). Pressure gradients driven by waves and currents interact with sediment topography (Precht and Huettel 2003), and pump solutes and particles from the overlying water into the sediment (Rusch and Huettel 2000;Reimers et al 2004). Advective transport leads to an acceleration of organic matter mineralization and a stimulation of biogeochemical cycling proportional to the extent of pore-water exchange (De Beer et al 2005).…”