Hot Fire In Cold Ice: Searching For Volcanic Eruptions In Antarctic Snow

Budner, a graduate student pursuing a doctorate in chemistry at South Dakota State University, is working with Jihong Cole-Dai, assistant professor of chemistry and biochemistry, on a research project examining the chemical composition of ice core samples from Antarctica.

The project started two years ago and involves investigating major volcanic eruptions over the last 1,500 years. The research goal is to determine if and how they are related to changes in the earth’s climate, according to Cole-Dai.

"When a volcano goes off, it puts a lot of gases into the atmosphere and they stay in the atmosphere and circle the globe for a lon g time," he says. "The gases eventually turn into tiny sulfuric acid droplets that can block and prevent sunlight from reaching the earth’s surface. This helps cool the climate as a whole. In Antarctica, the volcanic sulfuric acid becomes part of the snow that falls and accumulates year after year."

The snow and ice samples that Budner and Cole-Dai are examining are from ice cores drilled at the South Pole. The cores, which are kept in long cylinder tubes, are stored at the National Ice Core Laboratory in Denver. Upon request, cores are shipped to SDSU to be analyzed for chemical composition in the Ice Core Environmental Chemistry Laboratory (ICECL).

New freezer aids research

Built in fall 2002, the SDSU lab is a 200-square-foot freezer on the second f loor of Shepard Hall to store, prepare, and analyze snow and ice samples. The new freezer, kept at minus twenty degrees centigrade at all times, eliminates the need for Cole-Dai and his team to drive to Denver to work on the ice cores.

"Before, we had to prepare our samples there and bring them here for analysis," he says. "That took a lot of time and effort. Now we can make the samples in our own freezer."

The team, including Budner, graduate student Dave Ferris, and a number of undergraduate students, has conducted chemical analysis on more than 4,000 individual ice core samples, representing snow accumulated for more than a thousand years.

"Ice cores can give you very detailed information about the atmosphere," explains Cole-Dai. "By knowing how ol d the snow is at any depth you get a snapshot going back in time of the chemical composition of the air. This is very important if you want to look at how the climate of the earth has changed and the role of volcanoes in this process."

Studied by scientists worldwide

Budner is studying the results of the chemical analysis to build a year-by-year history of major volcanic eruptions over the last millenium.

Last June, Budner traveled to Santorini, Greece, to share his findings with other scientists, who came from all over the world to study information about volcanism in the earth’s atmosphere. His findings confirmed earlier evidence that five major eruptions took place during the thirteenth century, which was a period of significant change in the earth’s climate.

"We see a major climatic transition between what’s called the medieval warm period and the little ice age," he says. "There’s a strong possibility that these big eruptions had something to do with the climatic change from warm to cold during that time period."

Budner, a native of Alamosa, Colorado, calls the research "a good fit." He came to SDSU after spending a summer in Alaska on an ice field doing similar research.

"I’ve always enjoyed working with snow and ice," he says. "When I came here and met Dr. Cole-Dai, it was natural and exciting to become involved with his research. It’s real interesting to see events in ice that occurred thousands of years ago. It’s also cool in the summer when it’s ninety degrees outside."

New project underway

The ice core research has spawned another project that figures to greatly enhance Budner’s work. Using an electric band saw in the freezer, Budner cuts the ice cores into ice-cube shaped sizes. Before, he had to peel away the outer layers of the cylindrical ice tubes to get to the clean inner core, which is a slow, laborious process, according to Cole-Dai.

"We can’t use the cylinder ice cores for analysis directly because when they come out of the ground, the outside is contaminated by the machines us ed in the drilling," he explains. "We have to use the clean inner part of the ice core to find the original chemical composition."

He indicates the amount of sulfuric acid in snow from volcanic eruptions is so small that it is easily masked by even slight contamination.

"It requires a lot of time, patience, and skills in handling the cores to obtain clean samples, especially when you are talking about thousands of samples. That’s why this project is taking two years and longer. And, since ice core researchers want to look at deeper ice cores and longer histories, the slow chemical analysis can be a bottleneck in obtaining scientific information, such as volcanic impact on climate from polar ice cores."

To speed up the process, Cole-Dai and his team are collaborating with scientists at the Desert Research Institute of the University of Nevada to develop a chemical analysis machine.

The machine would melt the clean inner core of an ice cylinder, and pump the water into a chemical analyzer for chemical measurements. Such a combination of a melter and an analyzer will automate the ice core chemistry analysis process and shorten the analysis time, Cole-Dai points out.

"The University of Nevada has a form of this melter that we want to look at and make im provements for our research. We will then try to integrate it with our chemical analyzers. Having an automated system is going to make this research faster and also reduce the possibility of contamination."

The ice core research project, including constr uction of the freezer, is funded by the National Science Foundation and SDSU.