S.G. Wakeham, C. Lee, Robert A. Armstrong, M.L. Peterson, J.C. Miquel, Z. Liu, J. Xue and I.F. Putnam.
MEDFLUX: Organic biomarkers in time-series and sinking velocity traps.

Abstract: In recent experiments at the French JGOFS DYFAMED site in the western Mediterranean, we collected
sinking particles using time-series traps and a trap modified to fractionate particles in-situ by their sinking
velocity between <1.6 !> 1000 m/d. Our goal was to characterize the in-situ sinking nature of particles,
followed by analysis of their chemical composition to evaluate relationships between organic matter,
mineral ballast, sinking, and decomposition. Analyses of lipids and amino acids in these trap samples and
application of multivariate analysis separates trap samples dominated by fresh diatom-derived organic
matter from those that contain substantial amounts of OM that has been reworked by zooplankton and
bacteria. The majority of particles (~40% of total mass) were observed to sink at 200-500 m/d and were
dominated by large diatom-derived aggregates that were delivered primarily during the spring bloom
period. The more slowly sinking particles carry with them a greater zooplankton and bacterial signature.
The combination of time-series and sinking-velocity traps provides a unique capability to determine the
behavior of sinking particulate matter with minimal handling.