Keynote talk for the
2nd Xiamen Symposium on Marine Environmental Sciences
Jan 7-9, 2015, Xiamen China
Flocculation — Transformation of terrestrial particles in the marine environment
J.P.M. Syvitski
CSDMS/INSTAAR, U Colorado, Boulder CO, 80309-0545, USA, Email
James.syvitski@colorado.edu;
The largest input of sediment into the coastal ocean is by rivers, of which most enters as
suspended sediment. The sediment-laden river waters often enter riding within the turbulence of
a surface plume wherein sediment rains out of the plume into the marine waters below and where
flocs form quickly and settle through the water column subject to other sedimentation processes
(e.g. differential settling, shear, zooplankton ingestion, bacterial growth, plankton interaction).
Underwater “in situ” cameras especially designed for studying flocsoffer up quantitative
information on how sediment particles grow and shrink in the coastal marine environment.
Together with other marine instruments, the following attributes of suspended particles can be
determined: in situ size distribution, particle sphericity, particle Reynolds number, particle drag
coefficient, equivalent spherical sedimentation diameter, excess floc density, floc mass
concentration, floc porosity, and floc mass flux. Over 7000 in situ images of suspended sediment
in coastal water were collected and analyzed from67 locations andareas in and around:
Greenland, Baffin Island, Labrador Sea, Gulf of St Lawrence, Alaska, Antarctica, and in water
depths up to 1000 m. The environments include those dominated by icebergs, river discharge,
and tidal mixing. The presentation will provide historical development of the study of marine
particles, background theory and highlights from these data to demonstrate the range in
flocculation dynamics and the impact on seafloor sedimentation rates.