Uncovering secrets at the bottom of the sea

Researchers at Southern Cross University are currently investigating whether the 'bottom of the sea' might hold undiscovered secrets about its ability to sequestrate carbon dioxide.

The project is being led by Professor Bradley Eyre, director of Southern Cross University's Centre for Coastal Biogeochemistry Research, who said the findings could change global understanding of the likely impact of human-produced CO2 emissions.

"If it turns out as we think, the research will reveal that permeable carbonate sands absorb CO2 from the ocean in greater quantities than previously thought," Professor Eyre said.

"The project will make a leading contribution to our global understanding of ocean acidification which is the decrease in the pH of the oceans caused by their uptake of anthropogenic carbon dioxide from the atmosphere."

Dr Isaac Santos, senior research scientist with the Centre for Coastal Biogeochemistry Research and co- investigator on the project said the role of ocean sediments in controlling CO2 levels might be significantly underestimated.

"Current global models examining global warming factor the ocean as a large swimming pool, or mass of water that does not really interact with the bottom sediments. Carbonate sands are formed by coral reef breakdown and algae deposition. These sands cover much of the ocean's floor and function as the coastal ocean's kidneys, filtrating huge volumes of seawater," Dr Santos said.

"When CO2-enriched, acidified seawater infiltrates porous sands, it stimulates the dissolution of calcium carbonate. The dissolving sands release calcium and consume CO2. We will set out to quantify the importance of this process."

The research project received $310,000 in Discovery Projects funding from the Australian Research Council in October last year. In addition, Dr Santos was awarded one of only 100 Australian Postdoctoral Fellowships as part of the funding for the project.

"The funding means we will be able to: access cutting edge technology and develop new approaches to test our hypotheses; and it will also cover field trips to the Great Barrier Reef where we will perform most of our experiments," Dr Santos said.

"Our Centre is the first to ask these questions worldwide. Previous work has treated those sands as a static material. We will be the first to explore the concept that these sands act as a filter and that high filtration rates enhance the ocean's CO2 buffering capacity. This may help solve one of the largest mysteries in the global carbon cycle – the missing carbon sink. Nobody knows what happens to about 40 per cent of our CO2 emissions to the atmosphere. Is part of that missing CO2 reacting with carbonate sands?"

"It is an exciting project to be a part of and we are delighted the Australian Research Council has further funded our work. I was also really pleased to receive the Fellowship because it puts me in a good position to compete for additional research funding in Australia and overseas and so we can continue with the high standard of research we are undertaking. I am proud to be part of a Centre that fosters excellence and is performing cutting edge research in a number of areas."

Southern Cross University received the highest classification of a 'well above world standard' rating in the field of geochemistry in the Excellence in Research for Australia (ERA) 2010 National report released in January this year.

Professor Eyre said the work being done by the Centre was an excellent example of the cutting-edge biogeochemical research being undertaken at SCU which contributed to those results.

Southern Cross GeoScience and researchers within the School of Environmental Science and Management are also key contributors to this field of research.

For more information about the Centre for Coastal Biogeochemistry visit www.scu.edu.au/coastal-biogeochemistry.

Photo: Dr Isaac Santos testing carbon dioxide concentrations in beach pore water.