image: Pictured is a glacial meltwater river that has drained from the Greenland Ice Sheet. These rivers contain high amounts of suspended glacial flour as the ice sheet acts like a natural bulldozer, giving the rivers a grey milky color view more
Credit: Image credit: Kathy Kasic (photographer).
Analysis of ice sheet weathering reveals that the concentrations of key trace elements in meltwaters are higher than concentrations found in typical rivers, according to a study. Ice sheets cover 10% of Earth's surface and are sensitive to climate warming, but little is known about the biogeochemical conditions beneath ice sheets. Jon Hawkings and colleagues report elevated concentrations of key trace elements in meltwaters from the Greenland and Antarctic Ice Sheets, with concentrations of most trace elements higher than or comparable to that of rivers. The authors examined the biogeochemical conditions of meltwater beneath the Antarctic Ice Sheet as well as meltwater emerging from the Greenland Ice Sheet, sampling for trace elements such as iron, which is crucial in elemental cycling. Trace element concentrations were higher in a hydrologically active subglacial lake more than 1,000 m beneath the Antarctic Ice Sheet surface, compared with glacial meltwater runoff from the Greenland Ice Sheet. However, both meltwater samples had trace element concentrations higher than that found in typical river systems. The high concentrations, despite the near-freezing water temperatures, indicate long water residence times, increased weathering of silicate and sulfide minerals in the rock underlying the ice sheet, or both. As the climate continues to warm, changes in trace element mobilization may have implications for nutrient cycling in local marine environments, with a potential impact on global carbon cycling, according to the authors.
Article #20-14378: "Enhanced trace element mobilization by Earth's ice sheets," by Jon R. Hawkings et al.
MEDIA CONTACT: Jon Hawkings, Florida State University, Tallahassee, FL; e-mail: jhawkings@fsu.edu
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Journal
Proceedings of the National Academy of Sciences