Aucun titre de diapositive

1
OBEX 2 Role of grazing on Fe chemistry
Obj. 3.2.3 Feedback of biological activity on Fe
speciation
KEOPS meeting, 2-3 March 2005, Marseille
2
SOIREE In-situ artificial Fe fertilisation
How bioavailable iron was retained in surface
waters and/or within the biota?
3
Diatom - Copepod
Temora longicornis, 1 mm
Thalassiosira weissflogii, 10 µm
55Fe
24h
Calanus helgolandicus, 2.5 mm
4
Experimental method - Principle
55Fediss
55Fe
Gross Ingestion
Excretion / Dissolution
After Vincent (2002)
5
Analytical development for Fe speciation
various types of resins (8-HQ, C18) various
pH various Fe ligands
55DFe
6
Evolution of Fe in different compartments
7
Relative impact of regeneration processes
Temora longicornis
19
21
22
39
55Feeggs
55Fecop
55Fe
Gross Ingestion
Fecal pellet production
55FeFP
Net Production
Assimilation
51
7
17
25
Calanus helgolandicus
Sloppy feeding
Excretion / Dissolution
FP Dissolution
Excretion
Eggs production
After Vincent (2002)
8
What do we plan to do during KEOPS?
I- To apply grazing experiments to natural
phyto- and mesozoo-plankton communities
III- Without addition of 55Fe, same experiments
to study the effect on porphyrine concentrations
and DMS/DMSP and other biogenic gases
9
What do we need during KEOPS?
1- Clean seawater (Go-Flo) 40 L / experiment
various size-fractionations 0.02-0.2-0.8-2-20-2
00-500 µm
2- Mesozooplankton grazing experiments net
towing (200 µm-500 µm)
3- Clean radioactive container (laminar flow
hood)
4- Access to the trace-metal clean container
(cleaning and preparation)
5- A place with binocular for zooplankton sorting
(in situ temperature)
6- Liquid scintillation counter
7- Deck-Incubators