In much of the global ocean the (Redfield) ratio of nitrogen (N) to P is remarkably constant, both in the concentrations of these nutrients in seawater and in the plankton species that it supports. A number of studies of sub-Antarctic mode water, a convectively formed descending water type identifiably by its exceptionally uniform properties, suggest that high latitude P cycling is altered from the Redfield balance resulting in unusually enriched P compared to low latitude waters .
Synchrotron based x-ray spectromicroscopy will be used to chemically characterize and spatially map, at sub micron dimensions, the abundance of several P forms (e.g. polyphosphates, organo-P compounds) in organisms and marine particulates. These samples will be taken along the cruise track of the I/B Oden as it transits from Punta Arenas to McMurdo Station, through the Bellingshausen, Amundsen and Ross Sea regions,and which will provide a unique data set from a remote and understudied ice shelf and under-ice ecosystem. Characterization of Antarctic ocean P status is expected to shed further light upon aspects of Southern Ocean P biogeochemistry.
As well as using novel characterization techniques, which may lead to a transformative restatement of aspects of Southern Ocean P chemistry, this project meets an additional SGER criteria of representing a quick response to an international field campaign opportunity afforded by the transect of the Swedish ice breaker I/B Oden from Punta Arenas to McMurdo through the Bellingshausen, Amundsen and Ross Seas.
