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Climate, Oceans and Phytoplankton: That Sinking Feeling*

Exploring the intricate relationship between oceans, climate change, and phytoplankton to understand the impact on global carbon cycles. Discussing carbon sequestration methods, biological pumps, and the critical role of iron in phytoplankton productivity.

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Climate, Oceans and Phytoplankton: That Sinking Feeling*

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  1. Climate, Oceans and Phytoplankton: That Sinking Feeling* Conservation Biology Oct 22, 2004 *With apologies to Bill Forsyth and Jorge Sarmiento (Nature 2000)

  2. Our plan for today: • Conservation and the ocean. • Why? Global carbon budget. • How? Carbon sequestration: injection • How? Carbon sequestration: “biological pump”

  3. Our plan for today: • Conservation and the ocean. • Kyoto • Carbon credits.

  4. How the oceans influence climate • Oceans and atmosphere are tightly linked. • Oceans are critical for storing heat (and carbon) • Powerful currents are moving waters - transporting heat • Deep-water currents influence extremes in climate • Minor changes in ocean current mean major (large scale) climate variations

  5. Global Carbon Cycle

  6. CARBON CYCLE ISSUES Roger Revelle 360 CO2 (ppm) “the grandfather of the greenhouse effect...” 310 • 40% of the atmospheric carbon remains in the atmosphere. • 2/3 from fossil fuel; 1/3 from clear of forests. • Sent warning of sea level changes due to greenhouse effect...

  7. DEEP WATERS are Undersaturated with CO2

  8. Absorption of CO2 in the Ocean: “new” and “void” CO2 (aq) CO2 + Ca+2 CaCO3 (ppt) (reactive, catalytic) pCO2 -22 +39 -20 +10

  9. P Inorganic CO2 CARBON SEQUESTERING - a PANACEA? Depth Case 1 Case 2 PSN 100 1000 Organic carbon

  10. Depth Option 1 Carbon Sequestering: injection 100 P 1000 Inorganic CO2

  11. Option 1 Carbon Sequestering: injection • Peter Brewer (MBARI) • Collection of CO2 gases from industry • Pump to below 1000 m. • CO2 gases will be denser than seawater and will remain as a liquid or as ice. • Movement depends on mid- or deep-water circulation. Plume formation and water circulation

  12. Movement • Uncertain effects on • benthic communities • Transportation and • processing costs

  13. Depth Option 2 Carbon Sequestering: Biological pump PSN 100 1000 Organic carbon

  14. IRON LIMITATION IN MARINE SYSTEMS

  15. John Martin Linked PHYTOPLANKTON PRODUCTIVITY With the CARBON CYCLE “Johnny Ironseed” • Looked at the oceans with an analytical eye.... • Developed an analytical approach that opened up a field of ocean chemistry • “Give me half a tanker, and I’ll create the next ice age.”

  16. Nitrate Cell Biomass + growth = ∑ needs (C, N, P, ?) Phosphate Silicate

  17. Nitrate Cell Biomass + growth = ∑ needs (C, N, P, Fe) Redfield ratio: 106:16:1: 0.008 C:N:P:Fe (cellular) So … for every gram of iron added, draw down 2.9 tonnes of carbon.

  18. So what is limiting the growth of the phytoplankton? FeSO4 Fe+2 + SO4-2 Fe+3 Fe(OH)x (ppt) Concentration mol L-1 Residence Time in Upper Waters (years)

  19. How does iron get to the Pacific? April 2001 http://science.nasa.gov/headlines/y2001/ast17may_1.htm

  20. “CLEAN” sampling and handling techniques Martin’s Small Bottle-experiments (small scale)

  21. Meso-scale studies to “test” the iron hypothesis: Does adding iron stimulate the growth of phytoplankton? IronExII SOFeX

  22. SOFeX - 64 km2 with 1 nM FeSO4 ... So, some ecosystems have major Nutrients ($$$) but limiting levels of Iron (cheap!)

  23. Quantifiable reduction in atmospheric CO2 in "patches" of iron fertilization. SOFEX. Watson, A.J., and others. 2000. Effect of iron supply on Southern Ocean CO2 uptake and implications for glacial atmospheric CO2. Nature 407: 730 - 733.

  24. Started with a mixed flagellate and diatom community

  25. Ended with a DIATOM-only community.

  26. Remove CO2 via Productivity SINK! Biological Pump! IronExII

  27. Meso-scale studies to “test” the iron hypothesis: Does adding iron stimulate the growth of phytoplankton? IronExII SOFeX

  28. To get the Biological Pump ... Pumping, need to grow diatoms and other heavy cells. Does the addition of iron always result in these heavy cells? Good (sp. density 1.1)... Better (sp. density 1.5)... Terrible! (sp. density 1.1)

  29. SERIES: fertilization of Ocean Station PAPA (2002) Funded through SOLAS (NSERC, CCAF etc.) Iron fertilization to measure: Growth, gas production, sinking 64 sq. km FeSO4 addition ~ 1-2 nM Fe in the surface water

  30. SERIES: fertilization of Ocean Station PAPA (2002) Funded through SOLAS (NSERC, CCAF etc.)

  31. SERIES: fertilization of Ocean Station PAPA (2002) Funded through SOLAS (NSERC, CCAF etc.)

  32. FeSO4 and SF6 (gas)

  33. SERIES: fertilization of Ocean Station PAPA (2002)

  34. In warm waters ... FeSO4 SO4-2 + Fe+2 Fe+3 Fe(OH)x (ppt)

  35. In warm waters ... But the cold waters of the North may be a different story

  36. CO2 CO2 CH4 DMS N2O Different story FeSO4 SO4-2 + Fe+2 Fe+3 Fe(OH)x (ppt)

  37. Consequences of fertilizing OS PAPA ... • Few Diatoms, lots of flagellates. • Flagellates were stimulated to grow • Respire at > 90% of carbon • Produce GHG that are more destructive than CO2 • The resulting phytoplankton are a bit suspect ....

  38. .... HARMFUL ALGAL BLOOMS The definition of a HAB is not clear-cut, since it is a societal term, not a scientific term, that describes a diverse array of blooms (both macroscopic and macroscopic) that can cause detrimental effects to national economies.

  39. One flagellate that dominated is .... Responsible for Paralytic Shellfish Poisoning (PSP)

  40. One of the diatoms that dominated was ... Chaetoceros sp. (a non-specific fish kill species)

  41. Another was Pseudo-nitzschia … a toxigenic diatom which produces domoic acid - responsible for Amnesiac Shellfish poisoning (ASP) in local waters

  42. Conclusions … so far. • There’s no great degree of success. • chemistry of iron limits use at different zones • The measurement of success is uncertain. • The consequences of fertilization may be detrimental at the regional scale • HABs • toxins • May show no net benefit to GHG emissions. • CO2 respired quickly • O2 stress in surface waters • CH4, DMS and N2O produced.

  43. Public ponderings…on scientific responsibility. “There are many of us who consider the oceans to be sacred…. We’ve let the cat out of the bag. We have to keep looking at it now whether we like it or not.” - Ken Coale “The biggest danger, in my view, is that large-scale iron fertilization will occur without the necessary understanding of just what will happen on scales ranging from single cells to ecosystems.” - John Martin

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