Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes
Warming air temperatures, shifting hydrological regimes and accelerating permafrost thaw in the catchments of the Arctic rivers is affecting their biogeochemistry. Arctic river monitoring is necessary to observe changes in the mobilization of dissolved organic matter (DOM) from permafrost. The Lena...
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ftdoajarticles:oai:doaj.org/article:60bdc7b17ab145f4b7ce640332cbcb7c 2023-05-15T14:53:01+02:00 Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes Bennet Juhls Colin A. Stedmon Anne Morgenstern Hanno Meyer Jens Hölemann Birgit Heim Vasily Povazhnyi Pier P. Overduin 2020-05-01T00:00:00Z https://doi.org/10.3389/fenvs.2020.00053 https://doaj.org/article/60bdc7b17ab145f4b7ce640332cbcb7c EN eng Frontiers Media S.A. https://www.frontiersin.org/article/10.3389/fenvs.2020.00053/full https://doaj.org/toc/2296-665X 2296-665X doi:10.3389/fenvs.2020.00053 https://doaj.org/article/60bdc7b17ab145f4b7ce640332cbcb7c Frontiers in Environmental Science, Vol 8 (2020) Lena River Arctic DOC CDOM optical indices stable water isotopes Environmental sciences GE1-350 article 2020 ftdoajarticles https://doi.org/10.3389/fenvs.2020.00053 2022-12-31T01:50:46Z Warming air temperatures, shifting hydrological regimes and accelerating permafrost thaw in the catchments of the Arctic rivers is affecting their biogeochemistry. Arctic river monitoring is necessary to observe changes in the mobilization of dissolved organic matter (DOM) from permafrost. The Lena River is the second largest Arctic river and 71% of its catchment is continuous permafrost. Biogeochemical parameters, including temperature, electrical conductivity (EC), stable water isotopes, dissolved organic carbon (DOC) and absorption by colored dissolved organic matter (aCDOM) have been measured as part of a new high-frequency sampling program in the central Lena River Delta. The results show strong seasonal variations of all biogeochemical parameters that generally follow seasonal patterns of the hydrograph. Optical indices of DOM indicate a trend of decreasing aromaticity and molecular weight from spring to winter. High-frequency sampling improved our estimated annual fluvial flux of annual dissolved organic carbon flux (6.79 Tg C). EC and stable isotope data were used to distinguish three different source water types which explain most of the seasonal variation in the biogeochemistry of the Lena River. These water types match signatures of (1) melt water, (2) rain water, and (3) subsurface water. Melt water and rain water accounted for 84% of the discharge flux and 86% of the DOC flux. The optical properties of melt water DOM were characteristic of fresh organic matter. In contrast, the optical properties of DOM in subsurface water revealed lower aromaticity and lower molecular weights, which indicate a shift toward an older organic matter source mobilized from deeper soil horizons or permafrost deposits. The first year of this new sampling program sets a new baseline for flux calculations of dissolved matter and has enabled the identification and characterization of water types that drive the seasonality of the Lena River water properties. Article in Journal/Newspaper Arctic lena river permafrost Directory of Open Access Journals: DOAJ Articles Arctic Frontiers in Environmental Science 8 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Lena River Arctic DOC CDOM optical indices stable water isotopes Environmental sciences GE1-350 |
spellingShingle |
Lena River Arctic DOC CDOM optical indices stable water isotopes Environmental sciences GE1-350 Bennet Juhls Colin A. Stedmon Anne Morgenstern Hanno Meyer Jens Hölemann Birgit Heim Vasily Povazhnyi Pier P. Overduin Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes |
topic_facet |
Lena River Arctic DOC CDOM optical indices stable water isotopes Environmental sciences GE1-350 |
description |
Warming air temperatures, shifting hydrological regimes and accelerating permafrost thaw in the catchments of the Arctic rivers is affecting their biogeochemistry. Arctic river monitoring is necessary to observe changes in the mobilization of dissolved organic matter (DOM) from permafrost. The Lena River is the second largest Arctic river and 71% of its catchment is continuous permafrost. Biogeochemical parameters, including temperature, electrical conductivity (EC), stable water isotopes, dissolved organic carbon (DOC) and absorption by colored dissolved organic matter (aCDOM) have been measured as part of a new high-frequency sampling program in the central Lena River Delta. The results show strong seasonal variations of all biogeochemical parameters that generally follow seasonal patterns of the hydrograph. Optical indices of DOM indicate a trend of decreasing aromaticity and molecular weight from spring to winter. High-frequency sampling improved our estimated annual fluvial flux of annual dissolved organic carbon flux (6.79 Tg C). EC and stable isotope data were used to distinguish three different source water types which explain most of the seasonal variation in the biogeochemistry of the Lena River. These water types match signatures of (1) melt water, (2) rain water, and (3) subsurface water. Melt water and rain water accounted for 84% of the discharge flux and 86% of the DOC flux. The optical properties of melt water DOM were characteristic of fresh organic matter. In contrast, the optical properties of DOM in subsurface water revealed lower aromaticity and lower molecular weights, which indicate a shift toward an older organic matter source mobilized from deeper soil horizons or permafrost deposits. The first year of this new sampling program sets a new baseline for flux calculations of dissolved matter and has enabled the identification and characterization of water types that drive the seasonality of the Lena River water properties. |
format |
Article in Journal/Newspaper |
author |
Bennet Juhls Colin A. Stedmon Anne Morgenstern Hanno Meyer Jens Hölemann Birgit Heim Vasily Povazhnyi Pier P. Overduin |
author_facet |
Bennet Juhls Colin A. Stedmon Anne Morgenstern Hanno Meyer Jens Hölemann Birgit Heim Vasily Povazhnyi Pier P. Overduin |
author_sort |
Bennet Juhls |
title |
Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes |
title_short |
Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes |
title_full |
Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes |
title_fullStr |
Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes |
title_full_unstemmed |
Identifying Drivers of Seasonality in Lena River Biogeochemistry and Dissolved Organic Matter Fluxes |
title_sort |
identifying drivers of seasonality in lena river biogeochemistry and dissolved organic matter fluxes |
publisher |
Frontiers Media S.A. |
publishDate |
2020 |
url |
https://doi.org/10.3389/fenvs.2020.00053 https://doaj.org/article/60bdc7b17ab145f4b7ce640332cbcb7c |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic lena river permafrost |
genre_facet |
Arctic lena river permafrost |
op_source |
Frontiers in Environmental Science, Vol 8 (2020) |
op_relation |
https://www.frontiersin.org/article/10.3389/fenvs.2020.00053/full https://doaj.org/toc/2296-665X 2296-665X doi:10.3389/fenvs.2020.00053 https://doaj.org/article/60bdc7b17ab145f4b7ce640332cbcb7c |
op_doi |
https://doi.org/10.3389/fenvs.2020.00053 |
container_title |
Frontiers in Environmental Science |
container_volume |
8 |
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1766324443897921536 |