Why does anyone care about minute amounts of trace elements in our oceans - elements found at concentrations of less than 100 parts per trillion? The International Polar Year or ’IPY’, an international collaborative effort researching polar regions, took place between 2007 and 2009 and effectively harnessed the human, technological and logistical resources of the international community to deliver an unprecedented view of the status of the polar regions. During IPY, a circumpolar, multidisciplinary snapshot of the Southern Ocean was obtained for the first time, with observations made of many properties, processes and regions that had not been measured before. Such scientific advances have led to growing recognition that the Southern Ocean influences climate and biogeochemical cycles on global scales. The IPY also saw the beginning of activity under a new program, GEOTRACES, a decade-long international study of the global marine biogeochemical cycles of trace elements and their isotopes. Fourteen bi-polar research expeditions were undertaken along key ocean sections between 2007 and 2009 under the aegis of GEOTRACES, both in the oceans around Antarctica and the Arctic. The Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) is a major participant in GEOTRACES in the Australasian region. A team of scientists within the ACE CRC’s ’Carbon’ Program is focussed on improving our understanding of trace elements in the Southern Ocean, and in particular identifying what affects their distributions, and the sensitivity of these distributions to changing environmental conditions. The Southern Ocean is of particular interest to GEOTRACES because iron limits primary productivity in much of this vast ocean basin, and change in the delivery and availability of iron will arguably be the single largest forcing of Southern Ocean ecosystem productivity and health in the next century and have flow on implications for our climate. Moreover, every living cell and organism on our planet needs other trace elements (such as zinc, copper, manganese and cobalt) for many functions, including as co-factors in enzymes, and thus co-limitation by such elements in the Southern Ocean is likely under certain environmental conditions. Therefore although these trace elements may be found in minute concentrations in the ocean, they are critically important, and their biogeochemical cycling has direct implications for the carbon cycle, climate change, ocean ecosystems and environmental contamination. The results of the IPY-GEOTRACES research has yielded the first full ocean section circumpolar measurements of micronutrient trace elements and isotopes in the Southern Ocean. These and related biogeochemical observations promise to reveal important information concerning primary production in this region, phytoplankton community structure, and ultimately, a better understanding of the importance of trace elements as regulators of climate change.

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