New clues shed light on the importance of Earth’s ice caps

Researchers examining the subglacial waters of Antarctica and Greenland have found that these waters have higher concentrations of important and vital elements than previously thought, which answers a great unknown for scientists researching to understand the geochemical processes of the Earth.

“The data from an Antarctic lake is particularly interesting,” said Jon Hawkings, postdoctoral fellow at Florida State University. “Most people tend to think of Antarctica as just ice, but we have known of these lakes under Antarctic glaciers for 40 years and over 400 of them currently have Some scientists call the world’s Antarctic subglacial environment the largest wetland. The challenge for scientists is that it is simply extremely difficult to sample them. “

Hawkings, along with colleagues from Florida State and Montana State University, this week released a new study in the Proceedings of the National Academy of Sciences explore these subglacial waters.

The study specifically examines liquid water under ice caps in Antarctica and Greenland. About 10% of the Earth’s land surface is covered by these ice caps, and these polar environments are undergoing rapid changes due to rising temperatures. Scientists are very interested in understanding these environments and how continued warming will affect critical geochemical processes in the future.

Hawkings analyzed the water samples focusing on so-called trace elements, chemicals that are present in very small amounts but are essential to microscopic organisms and therefore to the global carbon cycle. Scientists have believed for years that the waters under glaciers around the world contain these elements in such tiny amounts that they do not play a significant role in Earth’s geochemical and biological processes.

“What we found out is actually that ice caps are apparently more important to life processes than we originally thought,” said Robert Spencer, FSU associate professor of science. earth, ocean and atmosphere. “As great unknowns in our contemporary understanding of how our planet works are uncovered, it reminds us how much remains to be learned.”

For example, scientists expected to see less than 5 micrograms per liter of dissolved iron (an extremely important trace element) in some of these subglacial waters, but they saw as many as 1000 micrograms per liter. These large variations can make a major difference in the lifespan of extreme subglacial ecosystems and ocean waters that receive meltwater from the ice cap.

“These trace minerals are a lot like the vitamin tablets that people take every day,” Spencer said. “Although we only need small amounts of these materials, they are fundamental for the development of healthy ecosystems.”

Collecting subglacial waters for analysis is no easy task, however, especially in Antarctica. Researchers must work in remote and difficult environments.

Montana State University’s Hawkings and Spencer collaborators Professors John Priscu and Mark Skidmore orchestrated a logistically complex research expedition to Antarctica to drill more than 3,500 feet through the Antarctic ice sheet.

After receiving funding from the National Science Foundation in 2016 for the SALSA (Scientific Access to Subglacial Antarctic Lakes) project, Priscu led a field campaign that consisted of moving nearly one million pounds of gear by plane and tractor crossing the ice cap to the site.

Then, from December 2018 to January 2019, the SALSA project science team drilled approximately three-quarters of a mile of ice in Mercer Subglacial Lake, a lake more than 9 km long and 15 meters deep. They chose this particular lake because it was located at the junction of two streams of ice.

“We were interested in the physical, chemical and biological processes occurring in this specific lake, but there is also this larger context of these lakes being part of the larger hydrologic system below the ice cap,” Skidmore said. “We want to see what is being generated under the ice cap and how it connects to coastal environments.”

Skidmore took samples according to a protocol established by Hawkings, then sent them back to the United States via a temperature-controlled freighter, which took several months, and then shipped them to Tallahassee via overnight delivery in special coolers for keep sample temperatures stable.

Hawkings and his colleagues separately collected samples in Greenland from a large river of meltwater that emerged below the Leverett Glacier. The fieldwork, led by Jemma Wadham of the University of Bristol in the UK, consisted of monitoring the hydrological and geochemical characteristics of the river over a three-month period during the summer melt season.

Hawkings and Spencer then performed geochemical analyzes at specially designed laboratories at the FSU-based National High Magnetic Field Laboratory, which minimize dust or other environmental factors that could contaminate the samples.

The researchers said their collaborative resources and interdisciplinary approach ultimately resulted in a study that will advance their field.

“Discoveries are made at the intersection of disciplines,” said Priscu. “The PNAS The paper cuts across many disciplines and shows the power of international collaboration. The results of this manuscript have transformed our view of the influence of polar ice caps on the Earth system. ”