Transcript General objective

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
CO2,
T, light/UV, mixing, Fe, Si, ….
CH4,
DMSe
N2O
CH3I
CHX
COV
DMS
bacteria
virus
zooplankton
Structure of the
phytolankton community
bacteria
virus
zooplankton
C export
General objective of KEOPS:
To contibute to improve our understanding and prediction of
the response of the Southern Ocean to climate change.
specific objectives
 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),
 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.
Strategy for objective 1
0m
Transect A
Transect B
A11
Transect C
B11
100 m
C11
A5
B5
A1
C5
2
B1
1
C1
Temperature measured using sensors
attached to pengins (Chassarin et al. 2001)
 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.
Strategy for objective 2
Two contrasting environments
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
).
 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?
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.
Foreign participations
 NIOZ (NL)
CSIRO and ACE CRC.
UVB
NIWA (NZ) Cliff Law (biogenic gases)
0
Depth (m)
20
T1171
Day 12.3
40
60
80
100
120
1.2
140
1
120
100
0.8
80
0.6
60
0.4
40
0.2
20
140
26.9
160
0
27.1
27.3
Density (t)
27.5
Increase in [N2O] max at base of
mixed layer during SOIREE
Maximum N2O* nmol/l)
% N2O saturation
105
115
Integarted chlorophyll mg Chla m-2)
95
0
0 1 2 3 4 5 6 7 8 9 1011121314
Time (days)
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.
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…)