University of Tasmania, Australia

Oceanic primary production from dissolved gas measurements

This research is on applying a relatively new geochemical technique to measure net community production in the upper ocean. The method uses a mass spectrometer to determine dissolved oxygen/argon ratios in surface waters. The oxygen signal is influenced by primary production and non-biological processes like bubble dissolution and heating/cooling. Argon is only influenced by the non-biological processes, but chemically it is very similar to oxygen. By using the measured ratio, the non-biological effects on the oxygen signal can be removed and the net production in surface waters estimated. This new method has been used with great success in the Southern Ocean to make continuous underway measurements. There are opportunities to develop the work further, including collecting data in Antarctic waters, using similar data on Ar/N2 ratios measured by moored autonomous sensors, and comparing the measurements to more traditional techniques undertaken during multidisciplinary oceanographic studies. The project will be co-supervised by Tom Trull from the Institute of Marine and Antarctic Studies at UTAS and Bronte Tilbrook from CSIRO Marine and Atmospheric Research, under the aegis of the ‘Ocean Control of CO²’ research program of the Antarctic Climate and Ecosystems Cooperative Research Centre.