Changes in the composition and bioavailability of dissolved organic matter during sea ice formation

The Arctic Ocean receives a large amount of terrestrial dissolved organic matter (DOM) from rivers and more than half of this is removed during its passage through the Arctic Ocean. Terrestrial DOM is generally believed to have a low bioavailability and recent studies point to physicochemical proces...

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Published in:Limnology and Oceanography
Main Authors: Jørgensen, Linda, Stedmon, Colin A., Kaartokallio, Hermanni, Middelboe, Mathias, Thomas, David N.
Format: Article in Journal/Newspaper
Language:English
Published: 2015
Subjects:
Online Access:https://curis.ku.dk/portal/da/publications/changes-in-the-composition-and-bioavailability-of-dissolved-organic-matter-during-sea-ice-formation(a1cef03b-b2f4-41f4-9f29-d332641e89d2).html
https://doi.org/10.1002/lno.10058
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spelling ftcopenhagenunip:oai:pure.atira.dk:publications/a1cef03b-b2f4-41f4-9f29-d332641e89d2 2023-05-15T13:37:30+02:00 Changes in the composition and bioavailability of dissolved organic matter during sea ice formation Jørgensen, Linda Stedmon, Colin A. Kaartokallio, Hermanni Middelboe, Mathias Thomas, David N. 2015 https://curis.ku.dk/portal/da/publications/changes-in-the-composition-and-bioavailability-of-dissolved-organic-matter-during-sea-ice-formation(a1cef03b-b2f4-41f4-9f29-d332641e89d2).html https://doi.org/10.1002/lno.10058 eng eng info:eu-repo/semantics/restrictedAccess Jørgensen , L , Stedmon , C A , Kaartokallio , H , Middelboe , M & Thomas , D N 2015 , ' Changes in the composition and bioavailability of dissolved organic matter during sea ice formation ' , Limnology and Oceanography , vol. 60 , no. 3 , pp. 817-830 . https://doi.org/10.1002/lno.10058 article 2015 ftcopenhagenunip https://doi.org/10.1002/lno.10058 2022-05-25T22:50:33Z The Arctic Ocean receives a large amount of terrestrial dissolved organic matter (DOM) from rivers and more than half of this is removed during its passage through the Arctic Ocean. Terrestrial DOM is generally believed to have a low bioavailability and recent studies point to physicochemical processes such as sea ice formation as the source of the significant DOM removal in the Arctic Ocean. We present the results of a mesocosm experiment designed to investigate how sea ice formation affects DOM composition and bioavailability. We measured the change in different fluorescent dissolved organic matter (FDOM) fractions in sea ice, brines (contained in small pores between the ice crystals), and the underlying seawater during a 14 d experiment. Two series of mesocosms were used: one with seawater alone and one with seawater enriched with humic-rich river water. Abiotic processes increased the humic-like FDOM signal in the seawater below the ice during the initial ice formation. Humic-like FDOM fractions with a marine signal were preferentially retained in sea ice (relative to salinity), whereas humic-like FDOM with a terrestrial signal behaved more conservatively with respect to salinity. Amino acid-like FDOM and an unknown FDOM component, only previously found in Antarctic brines, were associated with biological activity and possibly extracellular polymeric substances in sea ice. An additional long-term (226–228 d) bioassay experiment with seawater collected from the mesocosm experiment revealed that 11% ± 2% of the bulk dissolved organic carbon (DOC) was bioavailable. However, 16% ± 12% of DOC expelled from the ice into the seawater below was bioavailable and the bioavailability of DOC in brine was even higher at 45%. DOM is highly susceptible to physicochemical changes during sea ice formation, leading to modifications in composition and increased bioavailability, which can in part explain terrestrial DOC removal in the Arctic Ocean. Article in Journal/Newspaper Antarc* Antarctic Arctic Arctic Ocean Sea ice University of Copenhagen: Research Antarctic Arctic Arctic Ocean Limnology and Oceanography 60 3 817 830
institution Open Polar
collection University of Copenhagen: Research
op_collection_id ftcopenhagenunip
language English
description The Arctic Ocean receives a large amount of terrestrial dissolved organic matter (DOM) from rivers and more than half of this is removed during its passage through the Arctic Ocean. Terrestrial DOM is generally believed to have a low bioavailability and recent studies point to physicochemical processes such as sea ice formation as the source of the significant DOM removal in the Arctic Ocean. We present the results of a mesocosm experiment designed to investigate how sea ice formation affects DOM composition and bioavailability. We measured the change in different fluorescent dissolved organic matter (FDOM) fractions in sea ice, brines (contained in small pores between the ice crystals), and the underlying seawater during a 14 d experiment. Two series of mesocosms were used: one with seawater alone and one with seawater enriched with humic-rich river water. Abiotic processes increased the humic-like FDOM signal in the seawater below the ice during the initial ice formation. Humic-like FDOM fractions with a marine signal were preferentially retained in sea ice (relative to salinity), whereas humic-like FDOM with a terrestrial signal behaved more conservatively with respect to salinity. Amino acid-like FDOM and an unknown FDOM component, only previously found in Antarctic brines, were associated with biological activity and possibly extracellular polymeric substances in sea ice. An additional long-term (226–228 d) bioassay experiment with seawater collected from the mesocosm experiment revealed that 11% ± 2% of the bulk dissolved organic carbon (DOC) was bioavailable. However, 16% ± 12% of DOC expelled from the ice into the seawater below was bioavailable and the bioavailability of DOC in brine was even higher at 45%. DOM is highly susceptible to physicochemical changes during sea ice formation, leading to modifications in composition and increased bioavailability, which can in part explain terrestrial DOC removal in the Arctic Ocean.
format Article in Journal/Newspaper
author Jørgensen, Linda
Stedmon, Colin A.
Kaartokallio, Hermanni
Middelboe, Mathias
Thomas, David N.
spellingShingle Jørgensen, Linda
Stedmon, Colin A.
Kaartokallio, Hermanni
Middelboe, Mathias
Thomas, David N.
Changes in the composition and bioavailability of dissolved organic matter during sea ice formation
author_facet Jørgensen, Linda
Stedmon, Colin A.
Kaartokallio, Hermanni
Middelboe, Mathias
Thomas, David N.
author_sort Jørgensen, Linda
title Changes in the composition and bioavailability of dissolved organic matter during sea ice formation
title_short Changes in the composition and bioavailability of dissolved organic matter during sea ice formation
title_full Changes in the composition and bioavailability of dissolved organic matter during sea ice formation
title_fullStr Changes in the composition and bioavailability of dissolved organic matter during sea ice formation
title_full_unstemmed Changes in the composition and bioavailability of dissolved organic matter during sea ice formation
title_sort changes in the composition and bioavailability of dissolved organic matter during sea ice formation
publishDate 2015
url https://curis.ku.dk/portal/da/publications/changes-in-the-composition-and-bioavailability-of-dissolved-organic-matter-during-sea-ice-formation(a1cef03b-b2f4-41f4-9f29-d332641e89d2).html
https://doi.org/10.1002/lno.10058
geographic Antarctic
Arctic
Arctic Ocean
geographic_facet Antarctic
Arctic
Arctic Ocean
genre Antarc*
Antarctic
Arctic
Arctic Ocean
Sea ice
genre_facet Antarc*
Antarctic
Arctic
Arctic Ocean
Sea ice
op_source Jørgensen , L , Stedmon , C A , Kaartokallio , H , Middelboe , M & Thomas , D N 2015 , ' Changes in the composition and bioavailability of dissolved organic matter during sea ice formation ' , Limnology and Oceanography , vol. 60 , no. 3 , pp. 817-830 . https://doi.org/10.1002/lno.10058
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op_doi https://doi.org/10.1002/lno.10058
container_title Limnology and Oceanography
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