Koffman Awarded NSF Grant to Develop a New Approach to “Fingerprinting” Atmospheric Dust

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Assistant Professor of Geology Bess Koffman (center) in her lab at Colby. Photo by Yoon S. Byun
By Kardelen Koldas '15
August 5, 2020

A team of scientists led by Assistant Professor of Geology Bess Koffman has been awarded a grant by the National Science Foundation Division of Polar Programs to develop a new approach for “fingerprinting” atmospheric dust in ice cores using geochemical processes.

Geochemical fingerprinting allows scientists to gain insight into the causes and impacts of abrupt climate changes, the stability of ice sheets, and their potential contributions to sea level rise, Koffman said. Her team will focus on the West Antarctic Ice Sheet and seek to understand its behavior during the last interglacial warm period, about 130,000 years ago.

Moreover, the team’s new approach for geochemical fingerprinting might be applied to Moon rocks or the extraterrestrial materials connected to NASA’s Mars Mission.

The new approach by lead investigator Koffman and her colleagues from Columbia University’s Lamont-Doherty Earth Observatory Sidney Hemming, chair of earth and environmental sciences, and Steve Goldstein, associate director of geochemistry, will use two already existing methods of fingerprinting—potassium/argon dating and strontium-neodymium-lead isotopes—that have never been combined in this way to trace the origins of atmospheric dust in ice cores. Every piece of sediment and speck of dust coming from Earth’s soil, blowing around in the atmosphere, carries that compositional signature as they travel, she explained. Geochemical fingerprinting allows scientists like Koffman to trace that material back to its origin.

“What we’ve found is that by combining these different approaches, we can really improve our understanding and our interpretation of that dust and where it comes from,” Koffman said. “That will allow us to answer long-standing questions about sources of dust, the impact of that dust as a source of nutrients into the Southern Ocean, where it’s thought to play a role in the exchange of carbon between the atmosphere and ocean. So that can have a pretty big impact on the global carbon cycle.”

But even though a lot of work’s been done on the provenance of dust in ice cores in Antarctica, results are unclear due to overlapping compositions in potential source areas.

“There are places in the world—especially in the Southern Hemisphere where I do a lot of my work—where you get ambiguous results using the traditional approaches for fingerprinting the sediment or the dust in ice cores,” Koffman said. “We want to merge these two approaches, but actually apply them to dust and ice cores, which is a really, really small amount of stuff. So it’s challenging to then get good data, but I think the power of the tool is worth this effort to make it happen.”

Among the questions: what happened during the last interglacial period? At that time the Earth was a bit warmer than today with higher sea levels. “Scientists are wondering, where exactly did that extra water come from? … And one of the chief regions of concern is West Antarctica,” she said. “We hope to apply this approach to ice core dust that will show us if West Antarctica experienced an ice sheet collapse 130,000 years ago. … So that’s an application that I think will be really powerful.”

The two-year grant of $209,189, including Colby’s award of $126,498, will allow approximately four Colby students and one Columbia student to participate in this research.

“By being involved both at Colby and at Lamont at Columbia, they will be involved in all aspects of the projects, both the sample processing and the analysis, and they’ll really get to learn the cutting-edge techniques in the field of geochemistry,” said Koffman, who has a world-class lab at Colby.

“They can be involved from start to finish of a real research project and get the hands-on experience of developing this method with us, testing it, and figuring out how to make it better, which is really fundamental work in sciences.”

Read about Koffman’s earlier work at Colby Magazine’s Climate Project here.