Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf
Fluvial discharge and coastal erosion of the permafrost-dominated East Siberian Arctic delivers large quantities of terrigenous organic carbon (Terr-OC) to marine waters. The composition and fate of the remobilized Terr-OC needs to be better constrained as it impacts the potential for a climate–carb...
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ftcopernicus:oai:publications.copernicus.org:bg52885 2023-05-15T15:09:12+02:00 Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf Salvadó, Joan A. Tesi, Tommaso Sundbom, Marcus Karlsson, Emma Kruså, Martin Semiletov, Igor P. Panova, Elena Gustafsson, Örjan 2018-09-27 application/pdf https://doi.org/10.5194/bg-13-6121-2016 https://www.biogeosciences.net/13/6121/2016/ eng eng doi:10.5194/bg-13-6121-2016 https://www.biogeosciences.net/13/6121/2016/ eISSN: 1726-4189 Text 2018 ftcopernicus https://doi.org/10.5194/bg-13-6121-2016 2019-12-24T09:51:51Z Fluvial discharge and coastal erosion of the permafrost-dominated East Siberian Arctic delivers large quantities of terrigenous organic carbon (Terr-OC) to marine waters. The composition and fate of the remobilized Terr-OC needs to be better constrained as it impacts the potential for a climate–carbon feedback. In the present study, the bulk isotope ( δ 13 C and Δ 14 C) and macromolecular (lignin-derived phenols) composition of the cross-shelf exported organic carbon (OC) in different marine pools is evaluated. For this purpose, as part of the SWERUS-C3 expedition (July–September 2014), sediment organic carbon (SOC) as well as water column (from surface and near-bottom seawater) dissolved organic carbon (DOC) and particulate organic carbon (POC) samples were collected along the outer shelves of the Kara Sea, Laptev Sea and East Siberian Sea. The results show that the Lena River and the DOC may have a preferential role in the transport of Terr-OC to the outer shelf. DOC concentrations (740–3600 µg L −1 ) were 1 order of magnitude higher than POC (20–360 µg L −1 ), with higher concentrations towards the Lena River plume. The δ 13 C signatures in the three carbon pools varied from −23.9 ± 1.9 ‰ in the SOC, −26.1 ± 1.2 ‰ in the DOC and −27.1 ± 1.9 ‰ in the POC. The Δ 14 C values ranged between −395 ± 83 (SOC), −226 ± 92 (DOC) and −113 ± 122 ‰ (POC). These stable and radiocarbon isotopes were also different between the Laptev Sea and the East Siberian Sea. Both DOC and POC showed a depleted and younger trend off the Lena River plume. Further, the Pacific inflow and the sea-ice coverage, which works as a barrier preventing the input of “young” DOC and POC, seem to have a strong influence in these carbon pools, presenting older and more enriched δ 13 C signatures under the sea-ice extent. Lignin phenols exhibited higher OC-normalized concentrations in the SOC (0.10–2.34 mg g −1 OC) and DOC (0.08–2.40 mg g −1 OC) than in the POC (0.03–1.14 mg g −1 OC). The good relationship between lignin and Δ 14 C signatures in the DOC suggests that a significant fraction of the outer-shelf DOC comes from “young” Terr-OC. By contrast, the slightly negative correlation between lignin phenols and Δ 14 C signatures in POC, with higher lignin concentrations in older POC from near-bottom waters, may reflect the off-shelf transport of OC from remobilized permafrost in the nepheloid layer. Syringyl ∕ vanillyl and cinnamyl ∕ vannillyl phenol ratios presented distinct clustering between DOC, POC and SOC, implying that those pools may be carrying different Terr-OC of partially different origin. Moreover, 3,5-dihydroxybenzoic acid to vanillyl phenol ratios and p -coumaric acid to ferulic acid ratios, used as a diagenetic indicators, enhanced in POC and SOC, suggesting more degradation within these pools. Overall, the key contrast between enhanced lignin yields both in the youngest DOC and the oldest POC samples reflects a significant decoupling of terrestrial OC sources and pathways. Text Arctic East Siberian Sea Ice Kara Sea laptev Laptev Sea lena river permafrost Sea ice SWERUS-C3 Copernicus Publications: E-Journals Arctic East Siberian Sea ENVELOPE(166.000,166.000,74.000,74.000) Kara Sea Laptev Sea Pacific Biogeosciences 13 22 6121 6138 |
institution |
Open Polar |
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Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Fluvial discharge and coastal erosion of the permafrost-dominated East Siberian Arctic delivers large quantities of terrigenous organic carbon (Terr-OC) to marine waters. The composition and fate of the remobilized Terr-OC needs to be better constrained as it impacts the potential for a climate–carbon feedback. In the present study, the bulk isotope ( δ 13 C and Δ 14 C) and macromolecular (lignin-derived phenols) composition of the cross-shelf exported organic carbon (OC) in different marine pools is evaluated. For this purpose, as part of the SWERUS-C3 expedition (July–September 2014), sediment organic carbon (SOC) as well as water column (from surface and near-bottom seawater) dissolved organic carbon (DOC) and particulate organic carbon (POC) samples were collected along the outer shelves of the Kara Sea, Laptev Sea and East Siberian Sea. The results show that the Lena River and the DOC may have a preferential role in the transport of Terr-OC to the outer shelf. DOC concentrations (740–3600 µg L −1 ) were 1 order of magnitude higher than POC (20–360 µg L −1 ), with higher concentrations towards the Lena River plume. The δ 13 C signatures in the three carbon pools varied from −23.9 ± 1.9 ‰ in the SOC, −26.1 ± 1.2 ‰ in the DOC and −27.1 ± 1.9 ‰ in the POC. The Δ 14 C values ranged between −395 ± 83 (SOC), −226 ± 92 (DOC) and −113 ± 122 ‰ (POC). These stable and radiocarbon isotopes were also different between the Laptev Sea and the East Siberian Sea. Both DOC and POC showed a depleted and younger trend off the Lena River plume. Further, the Pacific inflow and the sea-ice coverage, which works as a barrier preventing the input of “young” DOC and POC, seem to have a strong influence in these carbon pools, presenting older and more enriched δ 13 C signatures under the sea-ice extent. Lignin phenols exhibited higher OC-normalized concentrations in the SOC (0.10–2.34 mg g −1 OC) and DOC (0.08–2.40 mg g −1 OC) than in the POC (0.03–1.14 mg g −1 OC). The good relationship between lignin and Δ 14 C signatures in the DOC suggests that a significant fraction of the outer-shelf DOC comes from “young” Terr-OC. By contrast, the slightly negative correlation between lignin phenols and Δ 14 C signatures in POC, with higher lignin concentrations in older POC from near-bottom waters, may reflect the off-shelf transport of OC from remobilized permafrost in the nepheloid layer. Syringyl ∕ vanillyl and cinnamyl ∕ vannillyl phenol ratios presented distinct clustering between DOC, POC and SOC, implying that those pools may be carrying different Terr-OC of partially different origin. Moreover, 3,5-dihydroxybenzoic acid to vanillyl phenol ratios and p -coumaric acid to ferulic acid ratios, used as a diagenetic indicators, enhanced in POC and SOC, suggesting more degradation within these pools. Overall, the key contrast between enhanced lignin yields both in the youngest DOC and the oldest POC samples reflects a significant decoupling of terrestrial OC sources and pathways. |
format |
Text |
author |
Salvadó, Joan A. Tesi, Tommaso Sundbom, Marcus Karlsson, Emma Kruså, Martin Semiletov, Igor P. Panova, Elena Gustafsson, Örjan |
spellingShingle |
Salvadó, Joan A. Tesi, Tommaso Sundbom, Marcus Karlsson, Emma Kruså, Martin Semiletov, Igor P. Panova, Elena Gustafsson, Örjan Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf |
author_facet |
Salvadó, Joan A. Tesi, Tommaso Sundbom, Marcus Karlsson, Emma Kruså, Martin Semiletov, Igor P. Panova, Elena Gustafsson, Örjan |
author_sort |
Salvadó, Joan A. |
title |
Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf |
title_short |
Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf |
title_full |
Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf |
title_fullStr |
Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf |
title_full_unstemmed |
Contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer East Siberian Arctic Shelf |
title_sort |
contrasting composition of terrigenous organic matter in the dissolved, particulate and sedimentary organic carbon pools on the outer east siberian arctic shelf |
publishDate |
2018 |
url |
https://doi.org/10.5194/bg-13-6121-2016 https://www.biogeosciences.net/13/6121/2016/ |
long_lat |
ENVELOPE(166.000,166.000,74.000,74.000) |
geographic |
Arctic East Siberian Sea Kara Sea Laptev Sea Pacific |
geographic_facet |
Arctic East Siberian Sea Kara Sea Laptev Sea Pacific |
genre |
Arctic East Siberian Sea Ice Kara Sea laptev Laptev Sea lena river permafrost Sea ice SWERUS-C3 |
genre_facet |
Arctic East Siberian Sea Ice Kara Sea laptev Laptev Sea lena river permafrost Sea ice SWERUS-C3 |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-13-6121-2016 https://www.biogeosciences.net/13/6121/2016/ |
op_doi |
https://doi.org/10.5194/bg-13-6121-2016 |
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Biogeosciences |
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13 |
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22 |
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6121 |
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6138 |
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1766340427025219584 |