Data Acquisition: Sampling was performed on seawater collected from CTDs and minicosm experiments. Sampling involved the collection of 250 mL of seawater from each Niskin bottle and minicosm sampled. 100 mL of this was fixed with 1 mL of concentrated hydrochloric acid (HCl). A second 100 mL sample was filtered through a 0.45 micron filter and then fixed with HCl. The remaining water was filtered and purged, with the volatile gases eluted being trapped on gold wool enclosed in glass tubes. Data Analysis: Analysis of the gold wool tubes involved heating the tubes to separate the dimethylsulphide (DMS) and then purge and trap followed by gas chromatography (GC) to give the DMS concentration of the seawater sample. The fixed water samples and filtered fixed water samples were basified and then the DMS formed during this process was purged, trapped and analysed by GC to determine the dissolved and particulate dimethylsulphoniopropionate (DMSP) concentrations. Analysis is expected to take approximately one year to complete. Dataset Format: The data for the CTD sampling is in the following format - CTD Number; Niskin Bottle; DMS Concentration (nM); DMSP particulate concentration (nM); DMSP dissolved concentration (nM) The data for the minicosm sampling is in the following format: Minicosm Number; Minicosm Day; Hour; Tank Number; DMS Concentration (nM); DMSP particulate concentration (nM); DMSP dissolved concentration (nM) Acronyms Used: CTD - conductivity, temperature, pressure DMS - dimethylsulphide DMSP - dimethylsulphoniopropionate DMSO - dimethylsulphoxide GC - gas chromatography This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).

From 1991 to 2000 14 voyages have been completed in the Southern Ocean. Measurements of DMS (Dimethylsulfide) and DMSP (Dimethylsulfoniopropionate) have been carried out on surface and subsurface waters together with physical and biological measurements, with a view to understanding the main processes that affect DMS in the Southern Ocean. The first flux measurements have been carried out for DMS (see Curran and Jones 2000) in the last 3 years a concerted study has been carried out in the seasonal ice zone this study aims to identify the major phytoplankton assemblages responsible for DMS and DMSP production in the sea ice zone. It is thought that the sea ice zone also contributes to DMS in the atmosphere. This is being quantified. The fields in this dataset are: Site Date Time (local) Latitude Longitude Snow Cover (metres) Core Length (metres) DMSPt (nano Mols) Chlorophyl a (micrograms per litre) Sea Ice depth (metres) Pigments Fucoxanthin (micrograms per litre) Peridinin (micrograms per litre) 19' hexanoyloxyfucoxanthin (micrograms per litre) Salinity (ppt) Nitrate (micro Mols) Nitrite (micro Mols) Silicate (micro Mols) Phosphate (micro Mols)