Alpine Glaciers Important For Carbon Cycle 091812
September 18, 2012

Research Suggests Alpine Glaciers Play Critical Role In Carbon Cycle

Alan McStravick for - Your Universe Online

On the surface, the term “carbon cycle” can seem cold and almost prosaic. It´s a term that many of us learned and came to understand in a third-grade science class, with the help of rudimentary illustrations of the sun shining down on the grass that the cow was about to devour for lunch and oversized arrows tracing the flow of energy for us.

Like many things we learned in those early classes, it was diluted down to its most simple elements, and while it entered into our consciousness it was somehow able to carry on no further in our educational development. And also like many things we learned in those early classes, the concept itself, though brought to a level of understanding that made it easier to digest than the grass the cow was about to eat, is far more complex.

The carbon cycle is a fairly complex series of processes through which all of the carbon atoms in existence rotate. As an example, the same carbon atoms that reside in our bodies today have been used in countless other molecules dating back to the origins of our planet. Wood burned in a forest produces carbon dioxide that, through the process of photosynthesis, again becomes part of a new plant. As an omnivore or herbivore ingests the plant for its nutrients, and the same carbon atom from the burnt tree then becomes part of the creature that ate the plant.

Carbon cycling, though richly complex in reality, is actually a very simple idea. And an important one. Without a properly functioning carbon cycle, each and every aspect of life, both grand and small, would be changed dramatically.

Recently, an international collaboration headed by Tom Battin from the Department of Limnology at the University of Vienna looked at a little-studied example of a carbon cycle. His team´s task was to explore and determine the role of Alpine glaciers in the carbon-cycling process.  Glaciers are, in effect, nature´s freezers. Items that were deposited into the glaciers over several millennia became locked in a frozen tomb. And it is only on account of unprecedentedly rapid glacial melt that these carbon atoms are today beginning to be able to be studied at all.

In a study funded by the START program of the Austrian Science Foundation (FWF), researchers uncovered the unexpected biogeochemical complexity of dissolved organic matter that had been, until recently, locked inside the glacial systems. They followed the cycle hoping to witness the fate of these molecules as they carbon cycled into glacier-fed streams.

In an article published in Nature Geoscience titled “Biogeochemically diverse organic matter in Alpine glaciers and its downstream fate,” the research team details how their findings have expanded our current knowledge on the importance of the vanishing cryosphere for the planet´s biogeochemistry.

With the recession of glaciers worldwide effecting measurable changes on the hydrological cycle —  most notably in the form of rising sea-levels — it is apparent that our general understanding of the role of the glacier in the carbon cycle has been woefully lacking.

The study, led by an international team of researchers, was undertaken as collaboration between the Faculty of Life Sciences and the Faculty of Physics at the University of Vienna, the Max Plank Institute of Marine Microbiology at Bremen, the University of Oldenburg and the Wasser Cluster Lunz GmbH.

This skilled group of scientists and researchers examined the biogeochemical complexity of dissolved organic matter in 26 glaciers in the Austrian Alps. Using ultra-high resolution mass spectrometry, they have already identified thousands of organic compounds locked into the glacial ice. Two of the researchers, Christina Fasching and Peter Steier, both faculty at the Vienna Environmental Research Accelerator, have been able to accurately estimate the radiocarbon age of the trapped organic carbons at several thousand years.

The team also wanted to determine the bioavailability of ice-locked organic carbon for microbial heterotrophs in glacier-fed streams. Through both of these studies, for the first time, the researchers were able to relate, at a compound-specific level, the radiocarbon age and carbon bioavailability of distinct molecular groups.

The discovery that the biogeochemistry of the glacial organic matter was unexpectedly diverse was a pleasant surprise for the researchers.  Phenolic compounds derived predominately from vascular plants or soil, together with peptides and lipids, are believed to have had their genesis in microorganisms that dwell in the glacial ice. On the other hand, the by-products of burning fossil fuels seem to make up only a small part of the organic matter in the glacier.

Organic matter, once released from the glacier, may actually act to stimulate the heterotrophic metabolism in glacier-fed streams which otherwise typically lack energy sources. The ever-present carbon cycle carries on as microorganisms in glacier-fed streams may process the ancient organic carbon that will then leave the stream as carbon dioxide. The carbon dioxide then cycles back into the atmosphere.

The research conducted by this team has not only reminded us of a lesson learned long ago, behind our collective third-grade desks, but they have also furthered our collective understanding of the important role that mountain glaciers play in our carbon cycle.