Photochemical degradation of dissolved organic matter in arctic surface waters
A critical component in the global carbon cycle is the fate of dissolved organic matter (DOM) drained from soil into inland waters. However, we currently lack the information needed to predict the conversion of DOM to carbon dioxide (CO₂) versus partially oxidized or degraded compounds that are expo...
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ftumdeepblue:oai:deepblue.lib.umich.edu:2027.42/113534 2023-08-20T04:03:32+02:00 Photochemical degradation of dissolved organic matter in arctic surface waters Ward, Collin Patrick Cory, Rose Kling Ii, George W. Meyers, Philip A. Dick, Gregory James Blum, Joel D. 2015 application/pdf https://hdl.handle.net/2027.42/113534 en_US eng https://hdl.handle.net/2027.42/113534 Aquatic carbon cycling Arctic Aquatic photochemistry Dissolved organic matter Permafrost Surface waters Geology and Earth Sciences Science Thesis 2015 ftumdeepblue 2023-07-31T20:38:39Z A critical component in the global carbon cycle is the fate of dissolved organic matter (DOM) drained from soil into inland waters. However, we currently lack the information needed to predict the conversion of DOM to carbon dioxide (CO₂) versus partially oxidized or degraded compounds that are exported to the ocean. In arctic freshwaters, complete and partial photo-oxidation dominate DOM processing in the water column. However, the relative importance of these sunlight-driven pathways is likely governed by the chemical composition of DOM, which is expected to change with increasing ecological disturbances in the Arctic (e.g., tundra fires and permafrost thaw). Here, the molecular level controls on the photo-degradation of DOM in arctic freshwaters were investigated. The dominant sink of dissolved black carbon, a byproduct of tundra fires incorporated into the DOM pool, was partial photo-oxidation to compounds that are likely exported to the ocean. DOM draining the shallow organic mat of arctic soils contained higher molecular weight, more oxidized, and more unsaturated aromatic species compared to DOM draining the deeper permafrost layer. Despite differences in chemical composition (i.e., degree of saturation and oxidation), organic mat and permafrost DOM exhibited similar susceptibilities to complete photo-oxidation. Photo-decarboxylation of tannin-like compounds was likely an important mineralization pathway of organic mat and permafrost DOM, suggesting that these compounds may control the photo-mineralization of DOM in arctic surface waters. Permafrost DOM was significantly more susceptible to partial photo-oxidation compared to DOM leached from the organic mat, potentially due to the depletion of phenolic moieties with antioxidant properties in permafrost DOM that may quench the oxidation of DOM by sunlight. Thus, increased permafrost thaw and increased inputs of permafrost DOM to arctic surface waters may increase the rates of photochemical DOM processing of DOM and shift the dominant DOM degradation ... Thesis Arctic black carbon permafrost Tundra University of Michigan: Deep Blue Arctic |
institution |
Open Polar |
collection |
University of Michigan: Deep Blue |
op_collection_id |
ftumdeepblue |
language |
English |
topic |
Aquatic carbon cycling Arctic Aquatic photochemistry Dissolved organic matter Permafrost Surface waters Geology and Earth Sciences Science |
spellingShingle |
Aquatic carbon cycling Arctic Aquatic photochemistry Dissolved organic matter Permafrost Surface waters Geology and Earth Sciences Science Ward, Collin Patrick Photochemical degradation of dissolved organic matter in arctic surface waters |
topic_facet |
Aquatic carbon cycling Arctic Aquatic photochemistry Dissolved organic matter Permafrost Surface waters Geology and Earth Sciences Science |
description |
A critical component in the global carbon cycle is the fate of dissolved organic matter (DOM) drained from soil into inland waters. However, we currently lack the information needed to predict the conversion of DOM to carbon dioxide (CO₂) versus partially oxidized or degraded compounds that are exported to the ocean. In arctic freshwaters, complete and partial photo-oxidation dominate DOM processing in the water column. However, the relative importance of these sunlight-driven pathways is likely governed by the chemical composition of DOM, which is expected to change with increasing ecological disturbances in the Arctic (e.g., tundra fires and permafrost thaw). Here, the molecular level controls on the photo-degradation of DOM in arctic freshwaters were investigated. The dominant sink of dissolved black carbon, a byproduct of tundra fires incorporated into the DOM pool, was partial photo-oxidation to compounds that are likely exported to the ocean. DOM draining the shallow organic mat of arctic soils contained higher molecular weight, more oxidized, and more unsaturated aromatic species compared to DOM draining the deeper permafrost layer. Despite differences in chemical composition (i.e., degree of saturation and oxidation), organic mat and permafrost DOM exhibited similar susceptibilities to complete photo-oxidation. Photo-decarboxylation of tannin-like compounds was likely an important mineralization pathway of organic mat and permafrost DOM, suggesting that these compounds may control the photo-mineralization of DOM in arctic surface waters. Permafrost DOM was significantly more susceptible to partial photo-oxidation compared to DOM leached from the organic mat, potentially due to the depletion of phenolic moieties with antioxidant properties in permafrost DOM that may quench the oxidation of DOM by sunlight. Thus, increased permafrost thaw and increased inputs of permafrost DOM to arctic surface waters may increase the rates of photochemical DOM processing of DOM and shift the dominant DOM degradation ... |
author2 |
Cory, Rose Kling Ii, George W. Meyers, Philip A. Dick, Gregory James Blum, Joel D. |
format |
Thesis |
author |
Ward, Collin Patrick |
author_facet |
Ward, Collin Patrick |
author_sort |
Ward, Collin Patrick |
title |
Photochemical degradation of dissolved organic matter in arctic surface waters |
title_short |
Photochemical degradation of dissolved organic matter in arctic surface waters |
title_full |
Photochemical degradation of dissolved organic matter in arctic surface waters |
title_fullStr |
Photochemical degradation of dissolved organic matter in arctic surface waters |
title_full_unstemmed |
Photochemical degradation of dissolved organic matter in arctic surface waters |
title_sort |
photochemical degradation of dissolved organic matter in arctic surface waters |
publishDate |
2015 |
url |
https://hdl.handle.net/2027.42/113534 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic black carbon permafrost Tundra |
genre_facet |
Arctic black carbon permafrost Tundra |
op_relation |
https://hdl.handle.net/2027.42/113534 |
_version_ |
1774713924825907200 |