Under International Geosphere Biosphere Programme (IGBP), Joint Global Ocean Flux Studies(JGOFS) is a multi-disciplinary programme of the International Council of Scientific Unions (ICSU), which aims to study the flux of Carbon and other associated greenhouse gases in the oceans and to predict their role in governing the global climate. The Arabian Sea is believed to be a major source of many biogenic gases like Co2 and N2. The Indian JGOFS aims to study the flux of these gases in the Arabian Sea and to develop regional models that can predict short/long- term climatic changes.

Under the JGOFS programme, it has been decided to organise 5 dedicated JGOFS cruises of ORV Sagar Kanya in order to collect reliable data on (i) Primary production, phytoplankton pigments, new production, distribution and abundance of mesozooplankton/Microplankton and on bacterial abundance. (ii) Temperature, salinity and depth using CTD probes. (iii) Dissolved Oxygen, Nutrients, Total Carbondioxide and Ammonia. Nutrients from deeper waters to be analysed using autoanalyser. (iv) Mass flux, carbonate, and organic fluxes using multitrap float assembly. (v) Methane and Carbondioxide of surface air samples. (vi) Nitrous Oxide measurements of water column. In addition sediment traps will be deployed to estimate the export flux.

Major achievements of the programme are;

* Two pre-JGOFS cruises of ORV Sagar Kanya were conducted in April - 94 and January 95.

* Multi sediment traps and single cylindrical traps were deployed at 3 stations. Station-1 at 15øN; 65øE, Station-2 at 11øN; 65øE and Station-3 at 12øN; 70øE. The average flux in the shallow trap was 660 mg/day and the average flux in the deep trap (300 m) was less than 100 mg/day. This shows that a major portion of the organic matter is being remineralised in the upper water column just below the photic zone contributing to almost anoxic conditions.

* Samples collected in the previous JGOFS cruises were analysed. The results indicate;

- Maximum primary production at depths from 20-40 m.

- Column production increases from south to north.

- Major pathway of organic carbon during the premonsoon oligotrophic conditions in the JGOFS area is through bacteria.

- CTD measurements show the occurrence of 3 water masses - the Arabian sea high saline water mass, the Persian gulf water mass and the red sea water mass. The Arabian sea water mass occur in the upper 100 meter with core salinity ranging from 36.01 to 37.01. The Persian Gulf water mass occur between 200 to 300m with salinity varying from 35.31 to 35.89. The Red sea water mass is found at depth of about 550-700m with a salinity range of 35.35 to 35.58.

* Partial pressure of carbondioxide (PCO2) increases with depth due to the increased regeneration of organic material and the simultaneous decrease in pH. PCO2 reaches peak in the oxygen minimum zone. This indicates that the central and the Eastern Arabian sea could be a source for atmospheric CO2.