Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes
Thermokarst lakes play an important role in permafrost environments by warming and insulating the underlying permafrost. As a result, thaw bulbs of unfrozen ground (taliks) are formed. Since these taliks remain perennially thawed, they are zones of increased degradation where microbial activity and...
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Copernicus Publications
2021
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ftdoajarticles:oai:doaj.org/article:b2f8c077f8e64baa8fcde4f457b4701f 2023-05-15T15:16:31+02:00 Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes O. H. Meisel J. F. Dean J. E. Vonk L. Wacker G.-J. Reichart H. Dolman 2021-04-01T00:00:00Z https://doi.org/10.5194/bg-18-2241-2021 https://doaj.org/article/b2f8c077f8e64baa8fcde4f457b4701f EN eng Copernicus Publications https://bg.copernicus.org/articles/18/2241/2021/bg-18-2241-2021.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-18-2241-2021 1726-4170 1726-4189 https://doaj.org/article/b2f8c077f8e64baa8fcde4f457b4701f Biogeosciences, Vol 18, Pp 2241-2258 (2021) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/bg-18-2241-2021 2022-12-31T12:21:38Z Thermokarst lakes play an important role in permafrost environments by warming and insulating the underlying permafrost. As a result, thaw bulbs of unfrozen ground (taliks) are formed. Since these taliks remain perennially thawed, they are zones of increased degradation where microbial activity and geochemical processes can lead to increased greenhouse gas emissions from thermokarst lakes. It is not well understood though to what extent the organic carbon (OC) in different talik layers below thermokarst lakes is affected by degradation. Here, we present two transects of short sediment cores from two thermokarst lakes on the Arctic Coastal Plain of Alaska. Based on their physiochemical properties, two main talik layers were identified. A “lake sediment” is identified at the top with low density, sand, and silicon content but high porosity. Underneath, a “taberite” (former permafrost soil) of high sediment density and rich in sand but with lower porosity is identified. Loss on ignition (LOI) measurements show that the organic matter (OM) content in the lake sediment of 28±3 wt % ( 1 σ , n =23 ) is considerably higher than in the underlying taberite soil with 8±6 wt % ( 1 σ , n =35 ), but dissolved organic carbon (DOC) leaches from both layers in high concentrations: 40±14 mg L −1 ( 1 σ , n =22 ) and 60±14 mg L −1 ( 1 σ , n =20 ). Stable carbon isotope analysis of the porewater DOC ( δ 13 C DOC ) showed a relatively wide range of values from −30.74 ‰ to −27.11 ‰ with a mean of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">28.57</mn><mo>±</mo><mn mathvariant="normal">0.92</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="70pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="cc170526505501bc8c89012fee9729bb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" ... Article in Journal/Newspaper Arctic permafrost Thermokarst Alaska Directory of Open Access Journals: DOAJ Articles Arctic Talik ENVELOPE(146.601,146.601,59.667,59.667) Biogeosciences 18 7 2241 2258 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
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Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 O. H. Meisel J. F. Dean J. E. Vonk L. Wacker G.-J. Reichart H. Dolman Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Thermokarst lakes play an important role in permafrost environments by warming and insulating the underlying permafrost. As a result, thaw bulbs of unfrozen ground (taliks) are formed. Since these taliks remain perennially thawed, they are zones of increased degradation where microbial activity and geochemical processes can lead to increased greenhouse gas emissions from thermokarst lakes. It is not well understood though to what extent the organic carbon (OC) in different talik layers below thermokarst lakes is affected by degradation. Here, we present two transects of short sediment cores from two thermokarst lakes on the Arctic Coastal Plain of Alaska. Based on their physiochemical properties, two main talik layers were identified. A “lake sediment” is identified at the top with low density, sand, and silicon content but high porosity. Underneath, a “taberite” (former permafrost soil) of high sediment density and rich in sand but with lower porosity is identified. Loss on ignition (LOI) measurements show that the organic matter (OM) content in the lake sediment of 28±3 wt % ( 1 σ , n =23 ) is considerably higher than in the underlying taberite soil with 8±6 wt % ( 1 σ , n =35 ), but dissolved organic carbon (DOC) leaches from both layers in high concentrations: 40±14 mg L −1 ( 1 σ , n =22 ) and 60±14 mg L −1 ( 1 σ , n =20 ). Stable carbon isotope analysis of the porewater DOC ( δ 13 C DOC ) showed a relatively wide range of values from −30.74 ‰ to −27.11 ‰ with a mean of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">28.57</mn><mo>±</mo><mn mathvariant="normal">0.92</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="70pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="cc170526505501bc8c89012fee9729bb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" ... |
format |
Article in Journal/Newspaper |
author |
O. H. Meisel J. F. Dean J. E. Vonk L. Wacker G.-J. Reichart H. Dolman |
author_facet |
O. H. Meisel J. F. Dean J. E. Vonk L. Wacker G.-J. Reichart H. Dolman |
author_sort |
O. H. Meisel |
title |
Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes |
title_short |
Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes |
title_full |
Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes |
title_fullStr |
Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes |
title_full_unstemmed |
Porewater δ 13 C DOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes |
title_sort |
porewater δ 13 c doc indicates variable extent of degradation in different talik layers of coastal alaskan thermokarst lakes |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/bg-18-2241-2021 https://doaj.org/article/b2f8c077f8e64baa8fcde4f457b4701f |
long_lat |
ENVELOPE(146.601,146.601,59.667,59.667) |
geographic |
Arctic Talik |
geographic_facet |
Arctic Talik |
genre |
Arctic permafrost Thermokarst Alaska |
genre_facet |
Arctic permafrost Thermokarst Alaska |
op_source |
Biogeosciences, Vol 18, Pp 2241-2258 (2021) |
op_relation |
https://bg.copernicus.org/articles/18/2241/2021/bg-18-2241-2021.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-18-2241-2021 1726-4170 1726-4189 https://doaj.org/article/b2f8c077f8e64baa8fcde4f457b4701f |
op_doi |
https://doi.org/10.5194/bg-18-2241-2021 |
container_title |
Biogeosciences |
container_volume |
18 |
container_issue |
7 |
container_start_page |
2241 |
op_container_end_page |
2258 |
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1766346807957258240 |