Snow Sampling for Aeolian Material

As our drilling programme had been postponed for a year, Dr. Tim Haskell (PI of K131) kindly allowed Holly Winton to join his group to conduct her research project. Her project focuses on iron fertilisation of the Ross Sea region. Fine-grained aeolian dust (<10 0m) is believed to be a significant source of iron (Fe), which is the bio-limiting nutrient required for phytoplankton growth in the McMurdo Sound, Antarctica. The dust accumulates on sea ice and is added to the ocean each year when the ice breaks up. This 'fertilisation' of the ocean results in vast phytoplankton blooms that alter the food web and generate large volumes of biogenic sediment. In spite of the apparent importance of aeolian dust in 'biogeochemical cycling' in the McMurdo Sound, the details of the interdependence of the geological processes that supply the Fe and the page 3 resulting plankton growth are poorly understood. This project aims to quantify aspects of this biogeochemical cycle for the first time by analysing the physical (size distribution, abundance and variability) and chemical (total and "bio-available" Fe content) properties of the aeolian dust blown off the Antarctic continent, deposited and trapped in coastal snow and ice in the McMurdo Sound region. Snow samples from McMurdo sea ice were collected this season for these measurements with the intention of publishing the results in an internationally peer-reviewed journal and presenting them at the Antarctica New Zealand conference.

Figure 3: Satellite image of McMurdo Sound showing snow sampling sites in November 2009. Red dotes: Sampling sites. Blue dote: Base camp. North of the yellow line dark areas denote first year sea ice, while lighter areas denote multi-year ice. Yellow outline marks the continental and sea ice edge.