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

Advective transport of artificial and natural particles into permeable sedi ments was demonstrated in situ by field experiments in an intertidal Wadden Sea sandflat. Using dyed sediment, advective interfacial solute exchange w as shown to reach down at least 1.5 cm below surface. Particle depth distri butions depended on sediment permeability and particle size. Sandy sediment s were found to efficiently trap particulate material. At the beginning of the local phytoplankton spring bloom, an average m(2) of coarse-grained sed iment received 850-mg organic carbon per day by filtration of 14 liters of overlying water per hour. We discuss the relative importance of different t ransport mechanisms, and data from parallel studies on natural sediments at the same site are interpreted in close correlation to the results of the i n situ experiment.