Peter E. Jackson, Ph.D., Director, Support Group Dionex Asia Pacific Region, Dionex Corporation, Sunnyvale, CA, USA

Dionex ICS 3000 instruments are being used by Australian scientists studying Antarctic ice cores to look at the effects of climate change. This research begins with the planning and logistics to extract cores from the ice, which is often done in sections over years or decades. The cores can be as long as 1200 meters with a climate history stretching back 90,000 years and can take as long as six Antarctic summers to recover.

Cores are usually extracted in two meter lengths, and then cut in half for ease of storage and handling. They are shipped or flown back to a minus 20 °C freezer in the Australian Antarctic Division's glaciology department and each length of core is then cut into smaller pieces and analyzed for its chemical constituents.

The external surfaces of the cores are contaminated by dirty ice which has been exposed to the drill equipment, the modern day atmosphere and gloved human hands. But these sections can be used to measure hydrogen peroxide and isotopes of oxygen and hydrogen. The isotopes provide information about temperature at the time the snow was deposited, while hydrogen peroxide provides a measure of sunlight intensity. “The level of hydrogen peroxide is greater in summer than in winter, so it helps us identify the annual layers in the ice,” says Antarctic Division Ice Core Chemist, Dr Mark Curran.

The clean inner surface of the chemistry stick will be melted and analyzed using a dual channel Dionex ICS 3000 system. The IC system is used to measure quantities of ions, such as methyl sulphonic acid (MSA), chloride, sulphate, nitrate, sodium, calcium, potassium and magnesium.

According to Dr Curran, MSA is produced from the oxidation in the atmosphere of dimethylsulphide, which is itself produced by certain species of phytoplankton in the Southern Ocean. The amount of MSA in an ice core is related to the maximum extent of sea ice in the region. This is because in years where there is more sea ice, there is more phytoplankton activity following sea ice decay, and therefore more MSA production.

Sea salt, sodium chloride, is produced over the ocean when it's windy. More wind means more breaking waves and thus more seawater droplets entering the atmosphere. “This allows us to identify storms in the climate record,” Dr Curran says. “Because there tend to be more storms in winter than in summer, we can use this annual cycle for dating as well.” Sulphates give an indication of volcanic activity, while nitrates are thought to be produced by lightning in the tropics.

“So we can get a lot of information out of one small sample,” says Dr Curran, who has been a Dionex customer for over 10 years. To see the full text of this article, click here: http://www.aad.gov.au/default.asp?casid=37638.

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