25 March 2004

Thursday, 25 March 2004

Tracer and iron release day

This is the day we have all been waiting for, release day. The day dawned fine with only a moderate swell making it an ideal day to carryout the iron and tracer gas release. But before the release, two buoys were deployed. One of the buoys deployed is to mark the centre of the patch and the other is a Carioca buoy. This buoy makes numerous measurements that include seawater fCO2, sea surface temperature, and salinity. The data and buoys' position are then uplifted to satellite every few hours, thereby providing near 'real time' feedback on sea surface conditions. Two pre-release CTD casts were conducted before the infusion of iron to determine biological, chemical and physical parameters prior to iron and tracer gas infusion. By morning’s end, all the pre-release work had finished and the tracer and iron release began. The infusion involved pumping the tracer gas and iron solutions over a twelve-hour period into an area covering ~50km2 – the patch. If all goes well we should see an increase in the health status of the phytoplankton community within the patch over coming week.

The iron mapping team

The iron mapping team consists of one, Michael Ellwood (NIWA, NZ). The aim of the mapping team is to determine iron levels inside the patch during the course of the experiment. In addition, samples will be collected from inside and outside the patch to determine whether an increase in community health following iron addition influences the distribution and speciation of other trace elements.

Acknowledgements

Carioca buoy: Université Paris VI, Laboratoire d'Oceanographie, LODYC, France

Michael Ellwood, NIWA

Release of the Carioca buoy

The scramble for water from the CTD

The tanks that contain the dissolved iron and the tracer gases that were released.

Research subject: Oceans