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T, light/UV, mixing, Fe, Si, ….

General objective : To contibute to improve our understanding and prediction of the response of the Southern Ocean to the global climate change. Climate change. aérosols. T, light/UV, mixing, Fe, Si, …. CO 2 ,. CH 4 ,. COV. N 2 O. CHX. CH 3 I. DMS. DMSe. Structure of the

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T, light/UV, mixing, Fe, Si, ….

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  1. General objective: To contibute to improve our understanding and prediction of the response of the Southern Ocean to the global climate change Climate change aérosols T, light/UV, mixing, Fe, Si, …. CO2, CH4, COV N2O CHX CH3I DMS DMSe Structure of the phytolankton community bacteria virus zooplankton bacteria virus zooplankton C export

  2.  Identification of the mecanisms of natural iron fertilisation of the Kerguelen Plateau.  Flux studies in contrasting environments:  Process studies: To improve the knowledge of the biogeochemical processes involved in the C02 biological pump and biogas production, focusing on their responses to change in forcing parameters: iron supply, statrification, light (visible and UV), General objective of KEOPS: To contibute to improve our understanding and prediction of the response of the Southern Ocean to climate change. specific objectives

  3.  specific objective : Identification of the mecanisms of natural iron fertilisation of the Kerguelen Plateau. • Which mechanisms are responsible for the enrichment of deep water with iron? • Contact with the margin when deep waters circulates around the plateau • Remineralisation of sinking biogenic material after a massive bloom • Release from the shelf sediment • Dissolution of lithogenic particles issued from island • What is the major mechanism of the upward transfer of iron from deep waters • to the surface layer? • Strong interaction between tidal currents and the bottom topography generates • internal tides activity tranfering deep waterto the surface.

  4. 0 m Transect A Transect B A11 Transect C B11 150 M C11 A5 B5 100 m A1 C5 2 1 B1 C1 Temperature measured using sensors attached to  pengins (Chassarin et al. 2001) Strategy for objective 1

  5.  specific objective: Flux studies in contrasting environments: • Quantification of the flux of gases and aerosols at the ocean atmophere interface. • We will focuse on gases important in atmospheric chemistry and climate and on aerosol • as a source of iron to the ocean. • Quantification of the flux of carbon exported below the depth ofthe winter mixed layer.

  6. Two contrasting environments Strategy for objective 2 Parameters • Gases: CO2, DMS, DMSe, CH4, CO, N2O, CHNM, CHX, CHNO3. • Aerosols: • Carbon export: POC, PON, BSi, CaCO3, Ba, 234Th, 230Th, 232Th, delta ( 13C, 15N, 30Si ).

  7.  Process studies: To improve the knowledge of the biogeochemical processes involved in the C02 biological pump and biogas production, focusing on their responses to change in forcing parameters: iron supply, statrification, light (visible and UV), • Characterization of phytoplankton community: What physical and chemical • factors regulate phytoplankton growth and species composition. • Shifts in the structure of the phytoplankton communities in response to changes in the forcing parameters : iron light (visible and UV), stratification. • Do biological activity compete with photochemical process for the production of biogenic gases and iron speciation?

  8. Strategy for objective 3 • In situ observations in the two contrasting environments and along the gradients . • On Board Experiments (OBEX) • OBEX 1: Factors controling the growth of microbial community. • OBEX 2: The impact of grazing on the iron speciation and the production of gases. • OBEX 3: The impact of bacterial degradation and solar radiation on iron speciation and the production of biogenic gases. • OBEX 4: The impact of viral lysis on iron speciation and bioavailability.

  9. Foreign participations • NIOZ (NL) • CSIRO and ACE CRC. • UVB • NIWA (NZ) Cliff Law (biogenic gases)

  10. Increase in [N2O] max at base of mixed layer during SOIREE Development of [N2O]max coincident with integrated chlorophyll during SOIREE Changes in nitrous oxide production stimulated by biological response to Fe addition during SOIREE (Law et al, 2001) And also CH4 and CO.

  11. Foreign participations • NIOZ (NL) • CSIRO and ACE CRC. • UVB • NIWA (NZ) Cliff Law (biogenic gases) • NIWA (NZ) Phil Boyd (iron phytoplankton dynamics) • Univ. Delaware Dave Hutchins ? (phytoplankton, chemostat with change in forcing parameters, Fe, pCO2…)

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