Victoria University of Wellington, MSc

How Effective is the Ross Sea CO₂ Sink?

The Southern Ocean, an important sink for atmospheric CO₂, is expected to become less efficient with warming ocean temperatures, decreasing alkalinity, and changing atmospheric conditions. The Ross Sea is a particularly important region of CO₂ sequestration. Here, regionally sourced fine-grained aeolian dust (<10 mm) is believed to be a significant source of iron (Fe), which is the bio-limiting nutrient required for phytoplankton growth in the McMurdo Sound, Ross Sea, 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, which sequester CO₂ into their organic tissue during photosynthesis, generate large volumes of biogenic sediment, and have the potential to alter the food web. 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 resulting plankton growth are poorly understood.

This project aims to quantify important 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. This work directly contributes to the Antarctica New Zealand science strategy 2010 through Outcome 1 and indirectly contributes to Outcome 3.