Eastern Tropical Pacific (recently completed project):

    The lab was funded to test a relatively new sediment trap design in the waters off of Costa Rica and Panama.  This trap collects particles in the water column and separates them by settling velocity groups rather than collecting discrete time intervals.  Some recent studies have suggested much greater particle settling velocities than traditional values, and this has significant implications for elemental cycling in the oceans.  We tested the trap by mounting cameras above and below a valve within the trap to see if the trap design biases measured settling velocities.

Trap test area

    Marine snow falls into the top of trap and collects on an indented rotating sphere (IRS) - it looks like a big golf ball.  After 24 hours of collection, the sphere rotates 180°, dropping the collected particles into a funnel below, and eventually into rotating sample cups at the base of the trap.  Larger particles settle faster and are caught in the early sample cups, while smaller particles settle much slower and collect in the later sample cups.  The question of whether or not particles might "glue" themselves together while collecting on the rotating sphere has been raised.  If this is true, it would create artificially-large particles, and would bias particle settling rates towards higher velocities.  Our cameras measured the velocity of settling particles above the sphere and below the sphere after it rotated to see if the trap induces biases in apparent settling rates.

    Our initial results suggest there is no statistically significant difference in settling rates as measured by the camera above the rotating sphere and those determined by measuring the fluxes in the trap carousel tubes.

Cariaco Basin

Santa Barbara Basin

Eastern Tropical Pacific

Caribbean Precipitation

Bermuda Rise