POMME 1 - 2 - 3

Composés soufrés DMS et DMSP - Rosette

RESPONSABLE

METHODE ANALYSE & PRELEVEMENT

Type d'observations et mesures effectuées:
Composés soufrés du type DMS et DMSP(particulaire (p) et en solution (d)). Plus précisément: DMSPp<10um, DMSPp>10um, DMSPd et DMS

Stratégie d'échantillonnage suivie:
Réseau de stations CTD du leg 1, échantillonnage des 3 ou 5 premiers niveaux depuis la surface

DMS:dimethylsulfide

DMSP: dimethylsulfoniopropionate

DATA FROM LEG 1 of POMME 1, POMME 2 and POMME 3

Method of size fractionation of DMSP

We used 25 mm diameter 10 µm pore-size Nuclepore PC membranes and 25 mm Whatmann GF/F glass-fiber filters mounted on teflon cylinders that were allowed to sink slowly through seawater contained in a clean 0.3 l Teflon beaker, thus producing < 10 µm and < GF/F filtrates by reverse filtration.

The DMSP-content of particles over two size ranges (DMSPp > 10 µm and DMSPp < 10 µm) was indirectly measured by subtracting the total DMSP + DMS content of the filtrates (either <10 µm or <GF/F filtrates) from the total DMSP + DMS content of parent samples (either unfractionated whole water or <10 µm filtrate). Total DMSPp is obtained by subtracting the total DMSP + DMS content of the GF/F filtrate from the total DMSP + DMS content of unfractionated whole water.

Analytical methods

An 8 ml aliquot of the filtrates was transferred to glass tubes, treated with cold alkali, sealed with a teflon faced septa and allowed to sit at room temperature for at least 12 h. The content of a sample tube was drawn into a plastic syringe and immediately injected into the sparging device through a teflon faced septa. Sparged samples (Helium gas flow, 60 ml/min for 10 min) were cryotrapped on liquid nitrogen in a 0.16 mm diameter FEP-Teflon loop. Water vapor was removed using a Permapure device MD050-72F.

DMSP analyses were carried out at sea. Seawater DMS was also analysed on board immediately after filtration through Whatmann GF/F filters using the reverse flow technique described above.

DMS was calibrated from DMSP standards (Research Plus) prepared in the laboratory.

Samples were analyzed using either a Varian 3400CX or Varian 3800 gas chromatograph equipped with a Pulsed Flame Photometric Detector (PFPD).

Reference.

Belviso, S., Claustre, H., and Marty, J.-C., "Evaluation of the utility of chemo-taxonomic pigments as a surrogate for particulate DMSP," Limnol. Oceanogr. 46 : 989-995 (2001

 

DESCRIPTIF des FICHIERS

Fichiers en date du 21-01- 2002

Files: P1DMSDMSP, P2DMSDMSP, P3DMSDMSP

State: preliminary

units: nM

C1:station

C2:bottle

C3:depth

C4:DMS

C5:DMSPp

C6:DMSPp<10um

C7:DMSPp>10um

C8:DMSPd