New depth of understanding in the Pacific
ACE CRC scientists have recently undertaken a GEOTRACES section in the southwest Pacific Ocean. For the first time, full ocean water column samples - from surface to sea floor – were taken east of Australia for the analysis of trace elements and their isotopes. This was done using state-of-the-art collection systems deployed from the Australian Research Vessel the RV Southern Surveyor.
ACE CRC scientist Andrew Bowie led 11 scientists from seven nations on the voyage in May-June 2011, including Pier van der Merwe, Delphine Lannuzel and Fabien Queroue from the ACE Carbon program. The voyage was part of the Australasian contribution to a 10-year international program called GEOTRACES, which is looking at trace elements and isotopes in the ocean and establishing their sensitivity to changing environmental conditions.
The aim of the voyage was to sample waters for vital micronutrients, in particular iron, which help stimulate marine biological activity that enables the ocean to absorb CO2 (during the past 50 years oceans have absorbed about 30 per cent of CO2 released by human activities). The scientists on the voyage were also looking at the origins of trace elements, which come from dust, coastal sediments and in some cases have travelled thousands of kilometres from underwater volcanoes.
The voyage, which was carried out as a two-ship joint Australia – New Zealand expedition, took samples at 57 stations along a transect that began east of Australia, continued out into the South Pacific and terminated south of Tahiti. Smaller stations sampled ocean waters down to 1500 metres using a trace metal rosette. The full water column was also sampled at so-called ‘super’ or ‘mega’ stations, where large in situ pumps were also deployed.
In 23 days of ship time on the RV Southern Surveyor between Brisbane and Auckland, at times with the company of dolphins and albatrosses, more than 5000 samples were collected, with over 6000 litres of sea water filtered at sea. Some samples were analysed on board and a large number were brought back to be analysed in onshore laboratories in Australia and overseas.
A blog of the GP13 cruise can be found on the GEOTRACES website at www.geotraces.org.