The Role of Photochemistry in Driving the Composition of Dissolved Organic Matter Found in Glacier Environments ...

• Main Authors: Holt, Amy, Kellerman, Anne, Stubbins , Aron, Wagner, Sasha, McKenna, Amy, Fellman, Jason, Hood, Eran, Spencer, Robert
• Format: Dataset
• Language: English
• Published: Interdisciplinary Earth Data Alliance (IEDA) 2021
• Subjects: Other; dissolved organic matter, glaciers, water soluble organic carbon, atmospheric deposition, FT-ICR MS; Greenland; Juneau Icefield; glacier; Ice Sheet
• Online Access: https://dx.doi.org/10.26022/ieda/111996; https://ecl.earthchem.org/view.php?id=1996

Dissolved organic matter (DOM) in glacier environments is aliphatic-rich, yet studies have proposed DOM originates from allochthonous, aromatic and often aged material. Allochthonous organic matter (OM) is exposed to ultraviolet radiation both in atmospheric transport and post-deposition on the glacier surface. Thus, we evaluate photochemistry as a mechanism to account for the compositional disconnect between allochthonous OM sources and glacier DOM composition. Six solid endmember OM sources were leached in ultrapure water and photo-irradiated for 28-days in a solar simulator, until > 90 % of initial chromophoric DOM was removed. Ultrahigh-resolution mass spectrometry was used to compare the molecular composition of leachates pre- and post-irradiation to DOM sampled from supraglacial and bulk runoff from the Greenland Ice Sheet and Juneau Icefield, respectively. Photo-irradiation drove molecular level convergence between the initially aromatic-rich leachates and aromatic-poor glacial samples, selectively ...