Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff
Dissolved organic matter (DOM) in glacier runoff is aliphatic-rich, yet studies have proposed that DOM originates mainly from allochthonous, aromatic, and often aged material. Allochthonous organic matter (OM) is exposed to ultraviolet radiation both in atmospheric transport and post-deposition on t...
Published in: | Journal of Geophysical Research: Biogeosciences |
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Language: | English |
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American Geophysical Union
2021
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Online Access: | http://hdl.handle.net/11122/12858 |
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ftunivalaska:oai:scholarworks.alaska.edu:11122/12858 2023-05-15T16:20:27+02:00 Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff Holt, Amy D. Kellerman, Anne M. Li, Wenbo Stubbins, Aron Wagner, Sasha McKenna, Amy Fellman, Jason B. Hood, Eran Spencer, Robert G. M. 2021-11-04 http://hdl.handle.net/11122/12858 en_US eng American Geophysical Union Holt, A. D., Kellerman, A. M., Li, W., Stubbins, A., Wagner, S., McKenna, A., et al. (2021). Assessing the role of photochemistry in driving the composition of dissolved organic matter in glacier runoff. Journal of Geophysical Research: Biogeosciences, 126, e2021JG006516. https://doi. org/10.1029/2021JG006516 http://hdl.handle.net/11122/12858 Journal of Geophysical Research: Biogeosciences Dissolved organic matter (DOM) Glacier runoff Photochemistry Juneau Icefield Greenland Ice Sheet Article 2021 ftunivalaska https://doi.org/10.1029/2021JG006516 2023-02-23T21:38:01Z Dissolved organic matter (DOM) in glacier runoff is aliphatic-rich, yet studies have proposed that DOM originates mainly 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 runoff DOM composition. Six endmember OM sources (including soils and diesel particulate matter) were leached 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 endmember leachates pre- and post-irradiation to DOM in supraglacial and bulk runoff from the Greenland Ice Sheet and Juneau Icefield (Alaska), respectively. Photoirradiation drove molecular level convergence between the initially aromatic-rich leachates and aromatic-poor glacial samples, selectively removing aromatic compounds (−80 ± 19% relative abundance) and producing aliphatics (+75 ± 35% relative abundance). Molecular level glacier runoff DOM composition was statistically indistinguishable to post-irradiation leachates. Bray-Curtis analysis showed substantial similarity in the molecular formulae present between glacier samples and post-irradiation leachates. Post-irradiation leachates contained 84 ± 7.4% of the molecular formulae, including 72 ± 17% of the aliphatic formulae, detected in glacier samples. Our findings suggest that photodegradation, either in transit to or on glacier surfaces, could provide a mechanistic pathway to account for the disconnect between proposed aromatic, aged sources of OM and the aliphatic-rich fingerprint of glacial DOM. Megan I. Behnke is thanked for collecting the Alaskan soil samples, Stephanie McColaugh for collecting the Russell Glacier samples, Casey Luzius for help with leachate preparations, and Sarah Ellen Johnston ... Article in Journal/Newspaper glacier glacier Greenland Ice Sheet Alaska University of Alaska: ScholarWorks@UA Bray ENVELOPE(-114.067,-114.067,-74.833,-74.833) Greenland Juneau Icefield ENVELOPE(-134.254,-134.254,58.916,58.916) Journal of Geophysical Research: Biogeosciences 126 12 |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
Dissolved organic matter (DOM) Glacier runoff Photochemistry Juneau Icefield Greenland Ice Sheet |
spellingShingle |
Dissolved organic matter (DOM) Glacier runoff Photochemistry Juneau Icefield Greenland Ice Sheet Holt, Amy D. Kellerman, Anne M. Li, Wenbo Stubbins, Aron Wagner, Sasha McKenna, Amy Fellman, Jason B. Hood, Eran Spencer, Robert G. M. Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff |
topic_facet |
Dissolved organic matter (DOM) Glacier runoff Photochemistry Juneau Icefield Greenland Ice Sheet |
description |
Dissolved organic matter (DOM) in glacier runoff is aliphatic-rich, yet studies have proposed that DOM originates mainly 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 runoff DOM composition. Six endmember OM sources (including soils and diesel particulate matter) were leached 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 endmember leachates pre- and post-irradiation to DOM in supraglacial and bulk runoff from the Greenland Ice Sheet and Juneau Icefield (Alaska), respectively. Photoirradiation drove molecular level convergence between the initially aromatic-rich leachates and aromatic-poor glacial samples, selectively removing aromatic compounds (−80 ± 19% relative abundance) and producing aliphatics (+75 ± 35% relative abundance). Molecular level glacier runoff DOM composition was statistically indistinguishable to post-irradiation leachates. Bray-Curtis analysis showed substantial similarity in the molecular formulae present between glacier samples and post-irradiation leachates. Post-irradiation leachates contained 84 ± 7.4% of the molecular formulae, including 72 ± 17% of the aliphatic formulae, detected in glacier samples. Our findings suggest that photodegradation, either in transit to or on glacier surfaces, could provide a mechanistic pathway to account for the disconnect between proposed aromatic, aged sources of OM and the aliphatic-rich fingerprint of glacial DOM. Megan I. Behnke is thanked for collecting the Alaskan soil samples, Stephanie McColaugh for collecting the Russell Glacier samples, Casey Luzius for help with leachate preparations, and Sarah Ellen Johnston ... |
format |
Article in Journal/Newspaper |
author |
Holt, Amy D. Kellerman, Anne M. Li, Wenbo Stubbins, Aron Wagner, Sasha McKenna, Amy Fellman, Jason B. Hood, Eran Spencer, Robert G. M. |
author_facet |
Holt, Amy D. Kellerman, Anne M. Li, Wenbo Stubbins, Aron Wagner, Sasha McKenna, Amy Fellman, Jason B. Hood, Eran Spencer, Robert G. M. |
author_sort |
Holt, Amy D. |
title |
Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff |
title_short |
Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff |
title_full |
Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff |
title_fullStr |
Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff |
title_full_unstemmed |
Assessing the Role of Photochemistry in Driving the Composition of Dissolved Organic Matter in Glacier Runoff |
title_sort |
assessing the role of photochemistry in driving the composition of dissolved organic matter in glacier runoff |
publisher |
American Geophysical Union |
publishDate |
2021 |
url |
http://hdl.handle.net/11122/12858 |
long_lat |
ENVELOPE(-114.067,-114.067,-74.833,-74.833) ENVELOPE(-134.254,-134.254,58.916,58.916) |
geographic |
Bray Greenland Juneau Icefield |
geographic_facet |
Bray Greenland Juneau Icefield |
genre |
glacier glacier Greenland Ice Sheet Alaska |
genre_facet |
glacier glacier Greenland Ice Sheet Alaska |
op_relation |
Holt, A. D., Kellerman, A. M., Li, W., Stubbins, A., Wagner, S., McKenna, A., et al. (2021). Assessing the role of photochemistry in driving the composition of dissolved organic matter in glacier runoff. Journal of Geophysical Research: Biogeosciences, 126, e2021JG006516. https://doi. org/10.1029/2021JG006516 http://hdl.handle.net/11122/12858 Journal of Geophysical Research: Biogeosciences |
op_doi |
https://doi.org/10.1029/2021JG006516 |
container_title |
Journal of Geophysical Research: Biogeosciences |
container_volume |
126 |
container_issue |
12 |
_version_ |
1766008367405334528 |