Novel technique drills more detail into ice core records

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Novel technique drills more detail into ice core records

Ancient Antarctic dust highlights evolving global conditions, researchers say

Glaciers can reveal vast archives of information about Earth's environmental past, but deciphering the origins of the matter within them can be a challenge.

Now, using a novel technique that enables researchers to directly analyze millions of individual particles at once, a new study has revealed that specks of dust trapped in Antarctic ice likely originated from a common source during the last Ice Age, between about 120,000 and 11,500 years ago.

To determine this, a team led by Stanislav Kutuzov, lead author of the study and a researcher in earth sciences at The Ohio State University, examined more than 2 million particles from ice core samples taken from Taylor Glacier in coastal East Antarctica. The researchers found that major shifts in the number and concentration of dust grains that settled during this time period were likely linked to large-scale environmental shifts in Earth's southern hemisphere.

"This result implies that atmospheric circulation changed when we transitioned to a warmer period, and sources like Australia and New Zealand began to contribute to local dust deposition," said Kutuzov.

Gaining a better understanding of these sources can offer clues into ancient climate systems, as well as improve predictions about how those systems may behave in the future.

Overall, the breadth of compositional data gathered in this work is consistent with results from past ice core investigations. However, this team's more precise measurement method - identifying and analyzing thousands of distinct particles with a specific type of mass spectrometry - offers substantially more insight about the mineralogy of the dust particles, confirming that this new technique can act as a powerful tool for environmental nanoscience.

"Normally, we are limited with analysis due to our sample volume," said Kutuzov. "But the way this new technique works, it only requires a tiny amount of water to detect a huge amount of information about each particle."

The study was recently published in the journal Scientific Reports.

Ice cores, precious scientific tools for studying Earth's past environmental memories, are increasingly endangered as global temperatures rise. Before they are lost to glacier melt, scientists are racing to survey and preserve them from as many global areas as they can.

Tropical glaciers such as the Quelccaya Ice Cap or Nevado Huascarán, for instance, have dust records that reflect regional signals, whereas dust found in more environmentally pristine areas such as Greenland and Antarctica tends to capture global changes to Earth's atmosphere.

What's more, unlike traditional ice cores that are drilled vertically from the glacier's surface down to bedrock, the Taylor Glacier ice core samples were collected horizontally, a method that can give researchers a more detailed look into a single specific time period.

This ability allowed the team to observe that the type and amount of dust in the atmosphere changed during this period, as well as note an uptick of iron in the air, a critical nutrient associated with ocean bioactivity.

"We went from a much colder, drier, dustier world to transitioning toward a more humid world leading up to the Holocene," said Kutuzov. "We see a relative enrichment in iron oxide at this time and with so much soluble iron available, theories suggest these conditions could have supported a lot more life."

Their analysis also identified the presence of thousands of volcanic particles in the ice core, likely as a result of occasional Victoria Land volcano eruptions nearly 14,800 years ago. Kutuzov said scientists could use these findings to develop a much-needed reference database for various minerals such as volcanic glass and dust from well-known source regions, especially as next-generation technologies inspire new ways to study ice cores.

"Using this new method to confirm what was known before with more certainty shows that it could be applied to different places and events where we don't know what happened," he said. Other such places could even include other planets, as researchers prepare for future glacial explorations on those that also have water-ice, like Mars or Europa, one of Jupiter's moons.

"There's so much excitement for these instruments that more and more researchers are applying them to look at their data from a completely different angle," said Kutuzov. "There are still unknowns, but discoveries like this are what push science."

Co-authors include John Olesik, Madeleine Lomax-Vogt and Lucas Carter from Ohio State; Gregory Lowry, Garret Bland, Jonas Wielinski and Ryan Sullivan from Carnegie Mellon University; and Paolo Gabrielli from the University of Turin in Italy. This study was supported by the U.S. Ice Drilling Program.

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