Particulate organic matter in the Lena River and its delta: from the permafrost catchment to the Arctic Ocean

Olga Ogneva; Gesine Mollenhauer; Bennet Juhls; Tina Sanders; Juri Palmtag; Matthias Fuchs; Hendrik Grotheer; Paul J. Mann; Jens Strauss

doi:10.5194/bg-20-1423-2023

Particulate organic matter in the Lena River and its delta: from the permafrost catchment to the Arctic Ocean

Olga Ogneva^*, Gesine Mollenhauer^*, Bennet Juhls, Tina Sanders, Juri Palmtag, Matthias Fuchs, Hendrik Grotheer, Paul J. Mann, Jens Strauss^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) into rivers and, ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers despite the likely impact of highly dynamic estuarine and deltaic environments on the transformation, storage, and age of OM delivered to coastal waters. Here, we studied particulate organic carbon (POC) dynamics in the Lena River delta and compared them with POC dynamics in the Lena River main stem along a ∼ 1600 km long transect from Yakutsk, downstream to the delta. We measured POC, total suspended matter (TSM), and carbon isotopes (δ13C and Δ14C) in POC to compare riverine and deltaic OM composition and changes in OM source and fate during transport offshore. We found that TSM and POC concentrations decreased by 70 % during transit from the main stem to the delta and Arctic Ocean. We found deltaic POC to be strongly depleted in 13C relative to fluvial POC. Dual-carbon (Δ14C and δ13C) isotope mixing model analyses indicated a significant phytoplankton contribution to deltaic POC (∼ 68 ± 6 %) and suggested an additional input of permafrost-derived OM into deltaic waters (∼ 18 ± 4 % of deltaic POC originates from Pleistocene deposits vs. ∼ 5 ± 4 % in the river main stem). Despite the lower concentration of POC in the delta than in the main stem (0.41 ± 0.10 vs. 0.79 ± 0.30 mg L−1, respectively), the amount of POC derived from Yedoma deposits in deltaic waters was almost twice as large as the amount of POC of Yedoma origin in the main stem (0.07 ± 0.02 and 0.04 ± 0.02 mg L−1, respectively). We assert that estuarine and deltaic processes require consideration in order to correctly understand OM dynamics throughout Arctic nearshore coastal zones and how these processes may evolve under future climate-driven change.

Original language	English
Pages (from-to)	1423-1441
Number of pages	19
Journal	Biogeosciences (BG)
Volume	20
Issue number	7
DOIs	https://doi.org/10.5194/bg-20-1423-2023
Publication status	Published - 12 Apr 2023

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@article{7c963f7cec244352ac123862683951db,

title = "Particulate organic matter in the Lena River and its delta: from the permafrost catchment to the Arctic Ocean",

abstract = "Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) into rivers and, ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers despite the likely impact of highly dynamic estuarine and deltaic environments on the transformation, storage, and age of OM delivered to coastal waters. Here, we studied particulate organic carbon (POC) dynamics in the Lena River delta and compared them with POC dynamics in the Lena River main stem along a ∼ 1600 km long transect from Yakutsk, downstream to the delta. We measured POC, total suspended matter (TSM), and carbon isotopes (δ13C and Δ14C) in POC to compare riverine and deltaic OM composition and changes in OM source and fate during transport offshore. We found that TSM and POC concentrations decreased by 70 \% during transit from the main stem to the delta and Arctic Ocean. We found deltaic POC to be strongly depleted in 13C relative to fluvial POC. Dual-carbon (Δ14C and δ13C) isotope mixing model analyses indicated a significant phytoplankton contribution to deltaic POC (∼ 68 ± 6 \%) and suggested an additional input of permafrost-derived OM into deltaic waters (∼ 18 ± 4 \% of deltaic POC originates from Pleistocene deposits vs. ∼ 5 ± 4 \% in the river main stem). Despite the lower concentration of POC in the delta than in the main stem (0.41 ± 0.10 vs. 0.79 ± 0.30 mg L−1, respectively), the amount of POC derived from Yedoma deposits in deltaic waters was almost twice as large as the amount of POC of Yedoma origin in the main stem (0.07 ± 0.02 and 0.04 ± 0.02 mg L−1, respectively). We assert that estuarine and deltaic processes require consideration in order to correctly understand OM dynamics throughout Arctic nearshore coastal zones and how these processes may evolve under future climate-driven change.",

author = "Olga Ogneva and Gesine Mollenhauer and Bennet Juhls and Tina Sanders and Juri Palmtag and Matthias Fuchs and Hendrik Grotheer and Mann, \{Paul J.\} and Jens Strauss",

note = "Funding information: This research is part of the “Changing Arctic Carbon cycle in the COastal Ocean Near-shore (CACOON)” project and has been supported by the Bundesministerium f{\"u}r Bildung und Forschung (grant no. 03F0806A) and the Natural Environment Research Council (grant no. NE/R012806/1). Bennet Juhls was funded by the European Space Agency (ESA) as part of the Climate Change Initiative (CCI) fellowship (ESA ESRIN/Contract no. 4000l3376l/2l/I-NB).",

year = "2023",

month = apr,

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doi = "10.5194/bg-20-1423-2023",

language = "English",

volume = "20",

pages = "1423--1441",

journal = "Biogeosciences (BG)",

issn = "1726-4170",

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number = "7",

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TY - JOUR

T1 - Particulate organic matter in the Lena River and its delta

T2 - from the permafrost catchment to the Arctic Ocean

AU - Ogneva, Olga

AU - Mollenhauer, Gesine

AU - Juhls, Bennet

AU - Sanders, Tina

AU - Palmtag, Juri

AU - Fuchs, Matthias

AU - Grotheer, Hendrik

AU - Mann, Paul J.

AU - Strauss, Jens

N1 - Funding information: This research is part of the “Changing Arctic Carbon cycle in the COastal Ocean Near-shore (CACOON)” project and has been supported by the Bundesministerium für Bildung und Forschung (grant no. 03F0806A) and the Natural Environment Research Council (grant no. NE/R012806/1). Bennet Juhls was funded by the European Space Agency (ESA) as part of the Climate Change Initiative (CCI) fellowship (ESA ESRIN/Contract no. 4000l3376l/2l/I-NB).

PY - 2023/4/12

Y1 - 2023/4/12

N2 - Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) into rivers and, ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers despite the likely impact of highly dynamic estuarine and deltaic environments on the transformation, storage, and age of OM delivered to coastal waters. Here, we studied particulate organic carbon (POC) dynamics in the Lena River delta and compared them with POC dynamics in the Lena River main stem along a ∼ 1600 km long transect from Yakutsk, downstream to the delta. We measured POC, total suspended matter (TSM), and carbon isotopes (δ13C and Δ14C) in POC to compare riverine and deltaic OM composition and changes in OM source and fate during transport offshore. We found that TSM and POC concentrations decreased by 70 % during transit from the main stem to the delta and Arctic Ocean. We found deltaic POC to be strongly depleted in 13C relative to fluvial POC. Dual-carbon (Δ14C and δ13C) isotope mixing model analyses indicated a significant phytoplankton contribution to deltaic POC (∼ 68 ± 6 %) and suggested an additional input of permafrost-derived OM into deltaic waters (∼ 18 ± 4 % of deltaic POC originates from Pleistocene deposits vs. ∼ 5 ± 4 % in the river main stem). Despite the lower concentration of POC in the delta than in the main stem (0.41 ± 0.10 vs. 0.79 ± 0.30 mg L−1, respectively), the amount of POC derived from Yedoma deposits in deltaic waters was almost twice as large as the amount of POC of Yedoma origin in the main stem (0.07 ± 0.02 and 0.04 ± 0.02 mg L−1, respectively). We assert that estuarine and deltaic processes require consideration in order to correctly understand OM dynamics throughout Arctic nearshore coastal zones and how these processes may evolve under future climate-driven change.

AB - Rapid Arctic warming accelerates permafrost thaw, causing an additional release of terrestrial organic matter (OM) into rivers and, ultimately, after transport via deltas and estuaries, to the Arctic Ocean nearshore. The majority of our understanding of nearshore OM dynamics and fate has been developed from freshwater rivers despite the likely impact of highly dynamic estuarine and deltaic environments on the transformation, storage, and age of OM delivered to coastal waters. Here, we studied particulate organic carbon (POC) dynamics in the Lena River delta and compared them with POC dynamics in the Lena River main stem along a ∼ 1600 km long transect from Yakutsk, downstream to the delta. We measured POC, total suspended matter (TSM), and carbon isotopes (δ13C and Δ14C) in POC to compare riverine and deltaic OM composition and changes in OM source and fate during transport offshore. We found that TSM and POC concentrations decreased by 70 % during transit from the main stem to the delta and Arctic Ocean. We found deltaic POC to be strongly depleted in 13C relative to fluvial POC. Dual-carbon (Δ14C and δ13C) isotope mixing model analyses indicated a significant phytoplankton contribution to deltaic POC (∼ 68 ± 6 %) and suggested an additional input of permafrost-derived OM into deltaic waters (∼ 18 ± 4 % of deltaic POC originates from Pleistocene deposits vs. ∼ 5 ± 4 % in the river main stem). Despite the lower concentration of POC in the delta than in the main stem (0.41 ± 0.10 vs. 0.79 ± 0.30 mg L−1, respectively), the amount of POC derived from Yedoma deposits in deltaic waters was almost twice as large as the amount of POC of Yedoma origin in the main stem (0.07 ± 0.02 and 0.04 ± 0.02 mg L−1, respectively). We assert that estuarine and deltaic processes require consideration in order to correctly understand OM dynamics throughout Arctic nearshore coastal zones and how these processes may evolve under future climate-driven change.

UR - https://www.scopus.com/pages/publications/85153956876

U2 - 10.5194/bg-20-1423-2023

DO - 10.5194/bg-20-1423-2023

M3 - Article

SN - 1726-4170

VL - 20

SP - 1423

EP - 1441

JO - Biogeosciences (BG)

JF - Biogeosciences (BG)

IS - 7

ER -

Particulate organic matter in the Lena River and its delta: from the permafrost catchment to the Arctic Ocean

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