Patterns of suspended particle distribution and transport in a large fjordlike estuary

Seasonal and spatial patterns of the distribution and transport of suspended particles in Puget Sound, a large fjordlike estuary, are a product of the interaction of the subtidal circulation with surface and bottom particle sources. The particle distribution differs from the distribution of hydrographic properties and is characterized by four persistant features: (1) a thin (<10 m), high‐turbidity surface layer, (2) a thick (∼50 m), low‐turbidity zone centered around the level of no net motion between net seaward and landward flow, (3) horizontal particle fronts at the sill entrances, and (4) a bottom nepheloid layer maintained by local resuspension. Removal of particles from the surface waters by advective downwelling at the seaward sill and gravitational settling throughout the basin make Puget Sound an efficient particle trap. Particles sedimented on the basin floor are transported preferentially landward by the action of erosion/deposition cycles enhanced by fortnightly intrusions of new marine water.