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Particle resuspension in the Columbia River plume near field

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Title Particle resuspension in the Columbia River plume near field
Names Spahn, Emily Y. (creator)
Homer-Devine, Alexander R. (creator)
Nash, Jonathan (creator)
Jay, David A. (creator)
Kilcher, Levi (creator)
Date Issued 2009-11-24 (iso8601)
Note Copyrighted by American Geophysical Union.
Abstract Measurements of suspended sediment concentration, velocity, salinity, and turbulent
microscale shear in the near-field region of the Columbia River plume are used to investigate
the mechanisms of sediment resuspension and entrainment into the plume. An east-west
transect was occupied during spring and neap tide periods in August 2005 and May 2006,
corresponding to low and high river discharge conditions, respectively. During the high-discharge
period the plume is decoupled from the bottom, and fine sediment resuspended
from the bottom does not leave the benthic boundary layer. The primary modes of sediment
transport associated with the plume are advection of sediment from the estuary and
removal of sediment from the plume by gravitational settling and turbulent mixing. In
contrast, the plume is much less stratified during low-discharge conditions, and large
resuspension events are observed that entrained sediment through the water column and into
the plume. Our measurements indicate that two factors control the magnitude and timing of
sediment resuspension and entrainment: the supply of fine sediment on the seabed and
the relative influence of tidal turbulence compared with buoyancy input from the river. The
latter is quantified in terms of the estuary Richardson number RiE. The magnitude of vertical
turbulent sediment flux is correlated with RiE during the low-flow period when there is a
sufficient supply of bottom sediment in the near-field region. Such sediment resuspension
may be an important mechanism for the delivery of bioavailable micronutrients to the plume
during the summer.
Genre Article
Topic sediment
Identifier Spahn, E. Y., A. R. Horner-Devine, J. D. Nash, D. A. Jay, and L. Kilcher (2009), Particle resuspension in the Columbia River plume near field, J. Geophys. Res., 114, C00B14.

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