Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska
Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three pe...
Published in: | Frontiers in Earth Science |
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2021
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ftdoajarticles:oai:doaj.org/article:53427dbbd4a649179e5f215647fd33ee 2023-05-15T15:18:30+02:00 Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska Emily M. Bristol Craig T. Connolly Thomas D. Lorenson Bruce M. Richmond Anastasia G. Ilgen R. Charles Choens Diana L. Bull Mikhail Kanevskiy Go Iwahana Benjamin M. Jones James W. McClelland 2021-01-01T00:00:00Z https://doi.org/10.3389/feart.2020.598933 https://doaj.org/article/53427dbbd4a649179e5f215647fd33ee EN eng Frontiers Media S.A. https://www.frontiersin.org/articles/10.3389/feart.2020.598933/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2020.598933 https://doaj.org/article/53427dbbd4a649179e5f215647fd33ee Frontiers in Earth Science, Vol 8 (2021) coastal erosion carbon flux nitrogen flux porewater chemistry permafost biogeochemistry Science Q article 2021 ftdoajarticles https://doi.org/10.3389/feart.2020.598933 2022-12-31T05:22:00Z Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year−1. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ13C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m−2 year−1 during the Holocene and 0.5 ± 0.1 g TOC m−2 year−1 during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m−1 year−1 during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year−1 from this 9 km coastline (12,318 metric tons C year−1) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km2 area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and ... Article in Journal/Newspaper Arctic Arctic Ocean Beaufort Sea north slope permafrost Alaska Directory of Open Access Journals: DOAJ Articles Arctic Arctic Ocean Frontiers in Earth Science 8 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
coastal erosion carbon flux nitrogen flux porewater chemistry permafost biogeochemistry Science Q |
spellingShingle |
coastal erosion carbon flux nitrogen flux porewater chemistry permafost biogeochemistry Science Q Emily M. Bristol Craig T. Connolly Thomas D. Lorenson Bruce M. Richmond Anastasia G. Ilgen R. Charles Choens Diana L. Bull Mikhail Kanevskiy Go Iwahana Benjamin M. Jones James W. McClelland Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska |
topic_facet |
coastal erosion carbon flux nitrogen flux porewater chemistry permafost biogeochemistry Science Q |
description |
Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year−1. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ13C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m−2 year−1 during the Holocene and 0.5 ± 0.1 g TOC m−2 year−1 during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m−1 year−1 during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year−1 from this 9 km coastline (12,318 metric tons C year−1) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km2 area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and ... |
format |
Article in Journal/Newspaper |
author |
Emily M. Bristol Craig T. Connolly Thomas D. Lorenson Bruce M. Richmond Anastasia G. Ilgen R. Charles Choens Diana L. Bull Mikhail Kanevskiy Go Iwahana Benjamin M. Jones James W. McClelland |
author_facet |
Emily M. Bristol Craig T. Connolly Thomas D. Lorenson Bruce M. Richmond Anastasia G. Ilgen R. Charles Choens Diana L. Bull Mikhail Kanevskiy Go Iwahana Benjamin M. Jones James W. McClelland |
author_sort |
Emily M. Bristol |
title |
Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska |
title_short |
Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska |
title_full |
Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska |
title_fullStr |
Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska |
title_full_unstemmed |
Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska |
title_sort |
geochemistry of coastal permafrost and erosion-driven organic matter fluxes to the beaufort sea near drew point, alaska |
publisher |
Frontiers Media S.A. |
publishDate |
2021 |
url |
https://doi.org/10.3389/feart.2020.598933 https://doaj.org/article/53427dbbd4a649179e5f215647fd33ee |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Beaufort Sea north slope permafrost Alaska |
genre_facet |
Arctic Arctic Ocean Beaufort Sea north slope permafrost Alaska |
op_source |
Frontiers in Earth Science, Vol 8 (2021) |
op_relation |
https://www.frontiersin.org/articles/10.3389/feart.2020.598933/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2020.598933 https://doaj.org/article/53427dbbd4a649179e5f215647fd33ee |
op_doi |
https://doi.org/10.3389/feart.2020.598933 |
container_title |
Frontiers in Earth Science |
container_volume |
8 |
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1766348690714263552 |