Researchers from the University of Wyoming, the U.S. Geological Survey, and the University of Montana have directly sampled water from underneath the Greenland Ice Sheet.
The waters were collected from boreholes drilled through as much as half a mile of ice to reach the ice sheet's bed. By examining the chemistry of the water, the researchers found that the rock underneath the ice is actively reacting with the Earth's atmosphere.
These reactions, known as chemical weathering, are occurring at rates comparable to landscapes not covered by ice. The samples were collected in a region of the ice sheet known as the ablation zone, where surface meltwater is able to reach the ice sheet's bed.
The interaction of the surface meltwater with rock ground to fresh, fine sediments by the ice's weight promotes the chemical weathering of the landscape. Similar rates of weathering had been previously found in small mountain glaciers.
But the mechanisms proposed for weathering in the mountain environment had depended on rare but highly reactive minerals to do most of the chemical work. The research on Greenland shows that the most common rock forming minerals can weather at substantial rates in the ice sheet environment.
Chemical weathering under the Greenland Ice Sheet Joseph A. Graly et al., http://dx.doi.org/10.1130/G35370.1.