Lee, C., Armstrong, R.A., Engel, A., Xue, J., Beck, A., Liu, Z. Cochran, J.K., Peterson, M.L., Wakeham, S.G., and Miquel, J.C. PERSPECTIVES ON MECHANISMS DRIVING PARTCULATE ORGANIC CARBON (POC) FLUX: INSIGHTS FROM MEDFLUX

Abstract: An introduction to processes influencing marine particulate organic carbon fluxes will be presented. We and others have recently shown that the flux of mineral matter (opal, carbonates, and dust) is an excellent predictor of POC flux. We hypothesized that this strong statistical association may be driven by physical protection of organic matter by ballast minerals and/or the need for a minimum fraction of organic matter to maintain particle integrity during sinking. To investigate the mechanistic basis of this association, we collected sinking particles using time-series and sinking-velocity sediment traps at the JGOFS DYFAMED site in the western Mediterranean. We measured organic and inorganic carbon, Si, Ca, Al and Ti, to characterize the organic and inorganic material in these particles. We also conducted laboratory experiments on aggregation and decomposition of mineral-forming and non-mineral-forming algae. Field and laboratory observations suggest that the association of POC and ballast material may be initiated by mineral-enhanced aggregation.