1. PERSPECTIVES ON MECHANISMS DRIVING PARTCULATE ORGANIC CARBON (POC) FLUX: INSIGHTS FROM MEDFLUX Cindy Lee, Rob Armstrong, Anja Engel, Jianhong Xue, Aaron Beck, Zhanfei Liu, Kirk Cochran, Michael Peterson, Stuart Wakeham, and Juan-Carlos Miquel ASLO 2005 Summer Meeting

2. Flux units: 10 15 gC/y Pool units: 10 15 gC Intermediate and deep ocean 38,100 Ocean Carbon Cycle 2/26 (from Doney, S.C. and D. Schimel 2002. Global change - The future and the greenhouse effect. Encyc. Life Sci., Macmillan Publ. Ltd., www.els.net)

3. (from USJGOFS Image Gallery) Bermuda Atlantic Time-Series Station Why care about sinking particulate matter? It is one of the few processes that removes C from the ocean for long enough to ameliorate the increasing CO 2 concentration over time. 3/26

4. Sargasso Sea Fluxes Carbonate Flux Organic C Flux CZCS pigments (mg C/m 2 d) (mg C/m 2 d) (mg/m 3 ) Phytoplankton Biomass (monthly average) Organic Carbon Flux (bimonthly average) Inorganic Carbon Flux (bimonthly average) (Deuser, W.G., F. E. Müller-Karger, R. H. Evans, O. B. Brown, W.E. Esaias and G. C. Feldman. 1990. Surface-ocean color and deep-ocean carbon flux: How close a connection? Deep-Sea Res. II 37: 1331-1343) 4/26

5. Sargasso Sea Elemental Fluxes Ca Mg Al Sr Mn Ti Ba Vx10 I (Deuser, W. G., E. H. Ross and R. F. Anderson. 1981. Seasonality in the supply of sediment to the deep Sargasso Sea and implications for the rapid transfer of matter to the deep ocean. Deep-Sea Res. 28: 495–505) 5/26

6. Martin Open Ocean Composite Curve 6/26 (Martin, J.H., G.A. Knauer, D.M. Karl, W.W. Broenkow. 1987. VERTEX: carbon cycling in the northeast Pacific. Deep-Sea Res. 34: 267-285) F=1.53(z/100) -0.858

7. Biological Carbon Pump active vertical migration fixation of C, N by phytoplankton grazing egestion passive sinking of POC, PIC aggregate formation respiration excretion respiration physical mixing of DOC consumption, repackaging CO 2 N2N2 Seabed Base of euphotic zone decomposition break up (bacteria) (zooplankton) Lateral advection 7/26(from OCTET Report, 2000)

8. Percent of Organic Carbon 105 m Trap 1000 m Trap >3500 m Trap Sediment 0 204060 Plankton Lipid Carbohydrate Uncharacterized POC Flux, mg/m d 1.0 0.01 80 100 Amino Acid 100 2 POC flux and major biochemical abundances in the Equatorial Pacific (Wakeham, S. G. and C. Lee. 1993. Production, transport, and alteration of particulate organic matter in the marine water column. In: M.H. Engel and S. A. Macko (eds) Organic Geochemistry, pp. 145-169. Plenum Press) Pigment 9/26

9. Organic carbon fluxes decrease with depth to varying degrees at different locations. The percent of total mass made up by organic carbon reaches a constant value at depth, ~5%. Carbon fluxes and concentrations behave differently. (Armstrong R. A., C. Lee, J.I. Hedges, S. Honjo and S.G.Wakeham. 2002. A new, mechanistic model for organic carbon fluxes in the ocean based on the quantitative association of POC with ballast minerals. Deep-Sea Res. II, 49: 219-236) 8/26

10. We hypothesized that ballast minerals on sinking particles physically protect a fraction of their associated organic matter, and that the ratio of organic carbon to ballast is key to predicting variability in export fluxes and sinking velocities of organic carbon. (Armstrong et al. 2002) Total Flux Ballast associated Labile 10/26

11. What should we know about sinking particles? Are ballast minerals a key to predicting carbon export? What role does aggregation play in sinking? Are ballast and aggregation equally important throughout the water column? Do minerals physically protect a fraction of their associated total organic matter? 11/26

12. U.S. Collaborators: Lynn Abramson, SUNY Robert Armstrong, SUNY Aaron Beck, SUNY Kirk Cochran, SUNY Anja Engel, SUNY->AWI Cindy Lee, SUNY Zhanfei Liu, SUNY Michael Peterson, Seattle Gillian Stewart, SUNY Jennifer Szlosek, SUNY Stuart Wakeham, Savannah Jianhong Xue, SUNY European Collaborators: Scott Fowler, Monaco Joan Fabres, UB->SUNY Beat Gasser, Monaco Madeleine Goutx, Marseille Catherine Guigue, Marseille Pere Masqué, UAB Juan Carlos Miquel, Monaco Brivaela Moriseau, Brest Olivier Rageneau, Brest Alessia Rodriguez y Baena, Monaco Richard Sempéré, Marseille Christian Tamburini, Marseille Elisabet Verdeny, Barcelona 12/26 See http://www.msrc.sunysb.edu/MedFlux/ for more information.http://www.msrc.sunysb.edu/MedFlux/

13. Slide 15 MedFlux Sampling site MONACO To test ballast ideas we collected sinking particles using sediment traps, in-situ pumps and nets at the French JGOFS DYFAMED site in the western Mediterranean. 13/26

14. Slide 4 14/26

15. MedFlux Time-series Mooring: March-May 2003 (Peterson, M.L., S.G. Wakeham, C. Lee, J.C. Miquel and M.A. Askea. 2005. Novel techniques for collection of sinking particles in the ocean and determining their settling rates. Limnol. Oceanogr. Methods, submitted.) In 2003, mass flux peaked after the spring bloom and rapidly decreased with time at both 200 and 800 m. We measured the percent organic carbon in the trap samples. The percent organic carbon is higher when mass fluxes are lower. 15/26

16. MedFlux Settling Velocity Trap: March-May 2003 At 200 m, highest particle flux occurs at rates between 200-500 m/d. Percent organic carbon is higher at lower settling velocities. (Peterson et al. submitted) 16/26 MedFlux 2003

17. Parameters are: %ASP, GLU, HIS, SER, ARG, GLY, BALA, ALA, TYR, GABA, MET, VAL, PHE, LEU, LYS, SER+GLY+THR, TAA, LIPIDS, Neuts/TFA, %MASS, Po, Th234, OC/MASS, IC/MASS, TN/MASS Positive correlation Negative correlation 17/26 MedFlux 2003

18. Elutriator 18/26

19. Mass 234 Th Activity Total Mass in Elutriator Fractions (g) 234 Th Activity (dpm/g) Most material falls at rates greater than 230 m/d. Th activity was higher at lower settling velocities. 19/26 MedFlux 2003

20. (Sheridan C.C., C. Lee, S.G. Wakeham, and J.K.B. Bishop. 2002. Suspended particle organic composition and cycling in surface and midwaters of the equatorial Pacific Ocean. Deep-Sea Res. I 49: 1983-2008) Organic Biomarkers as Diagenetic Indices 20/26

21. Faster sinking particles (NT 1-3) Slower sinking particles (NT 4 & 5) Principal components analysis of amino acids in elutriated NetTrap samples 21/26 MedFlux 2003

22. (Xue et al. In prep) 22/26 MedFlux 2003 May-July March-May Opal CaCO3 + Litho OM

23. (Xue et al. in prep) 23/26 MedFlux 2003 CaCO3 + Litho Opal OM

24. Laboratory experiment comparing naked and calcified coccolithophorids 24/26 (Lee, Engel et al. In prep)

25. 25/26 MedFlux 2005

26. “Unified Ballast-Aggregation Theory of Export” If mineralized plankton aggregate faster, then mineralized plankton would be preferentially exported from the euphotic zone, and aggregation could be considered as the first step in the association between carbon and minerals in sinking particles. Ballast may become more important at depth. This narrows the possible theories for preservation at depth. This makes the current acidification of the ocean even more worrisome as increasing acidification dissolves forams and coccolithophorids so that there might be less flux, less organic C export, and thus less CO 2 permanently removed from the surface ocean. 26/27