Scientists analyze lake

by Victor Paul

People wanting to know the weather report can just consult the muddy, sedimentary record of a lake core. At least, that’s what a group of scientists are doing this week.
Scientists from the Large Lakes Observatory in Duluth are examining tubes of sediment burrowed from an East African lake. The researchers said the cores display the climate history of an area and can predict future patterns. They will conduct their preliminary analysis at the University’s Limnological Research Center.
“It’s interesting because you’re trying to figure out what is going on around the world at certain times and you have very limited ways of doing that,” said Lindsay Schoenbohn who is working with the observatory. “You have to be clever.”
Lakes act as history books, recording the events that impact a region over time. As climactic, geophysical or biological changes occur, the effects of these changes are recorded in the sedimentary layers that shroud the bottoms of lake beds.
“We don’t know the language yet,” said professor Tom Johnson, director of the Duluth center, about “reading” the layers of sediment in the cores. “There’s an element of learning as we go. We try to pull in different lines of evidence to build a story that is consistent with the observations.”
The scientists’ efforts are the beginning of a three-year project to study cores from Lake Milawi in Milawi, East Africa. The group said they hope to work through five of the 16, 30-foot cores they obtained during two expeditions to Lake Milawi in 1997 and 1998.
Using equipment designed and built by geology professor Kerry Kelts, director of the University Limnological Research Center, the researchers intend on performing chemical and physical analyses. With this data, they will be able to determine a strategy for further, in-depth studies of the cores, Kelts said.
Lake coring is one of a number of ways that scientists try to uncover the history of climate and environmental changes over time. Studies of tree rings in North America and ice cores from a glacier in Peru have yielded observations similar to those taken from the preliminary analysis of the Lake Milawi cores, Johnson said.
One regional application of this study is to help determine the economic and agricultural planning of East Africa by predicting future drought conditions based upon historical evidence.
“The story we get from the lake will be integrated in the regional history of environmental change in East Africa,” said Michael Talbot, a professor from the University of Bergen in Norway.
Funding for this project and the Limnological Research Center comes largely from the National Science Foundation, a federal program which funds scientific research in different fields. Participants generate additional grants on their own.
The research center is unique because it facilitates collaboration among scientists in different fields. These researchers study lake cores for their own interests and share the information with each other.
“A place like this has a very large importance for its interaction,” Kelts said, “A rich reward for the University, something that is very tangible for graduate students.”