Selective preservation of old organic carbon fluvially released from sub-Arctic soils

Jorien E. Vonk, Bart E. Van Dongen, Örjan Gustafsson

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Amplified climate warming in the Arctic may cause thaw-remobilization of its large soil organic carbon (SOC) pool. Here we assess the remobilization and preservation of old SOC by the watershed-integrated radiocarbon signature of molecular SOC markers released from northernmost Scandinavia. The radiocarbon analyses revealed a remarkable fractionation for identical vascular plant markers (∼420‰ or ∼6000 14C years) upon settling from surface water to the underlying sediments. From this, we infer fluvial export of two SOC pools; a young surface peat component, and an old deep mineral soil component. The young pool exists as an easily degradable humic suspension, while the old pool is matrix protected from degradation and ballasted for preferential settling. The two soil types with highest OC in Arctic permafrost evidently exhibit different susceptibilities to degradation. Hence, a significant part of the thaw-released OC may simply be fluvially relocated to sediments instead of being emitted to the atmosphere.

Original languageEnglish
Article numberL11605
JournalGeophysical Research Letters
Volume37
Issue number11
DOIs
Publication statusPublished - Jun 2010

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soils
organic carbon
carbon
remobilization
soil
settling
markers
sediments
degradation
Scandinavia
peat
permafrost
vascular plant
sediment
soil type
surface water
fractionation
warming
climate
watershed

Cite this

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abstract = "Amplified climate warming in the Arctic may cause thaw-remobilization of its large soil organic carbon (SOC) pool. Here we assess the remobilization and preservation of old SOC by the watershed-integrated radiocarbon signature of molecular SOC markers released from northernmost Scandinavia. The radiocarbon analyses revealed a remarkable fractionation for identical vascular plant markers (∼420‰ or ∼6000 14C years) upon settling from surface water to the underlying sediments. From this, we infer fluvial export of two SOC pools; a young surface peat component, and an old deep mineral soil component. The young pool exists as an easily degradable humic suspension, while the old pool is matrix protected from degradation and ballasted for preferential settling. The two soil types with highest OC in Arctic permafrost evidently exhibit different susceptibilities to degradation. Hence, a significant part of the thaw-released OC may simply be fluvially relocated to sediments instead of being emitted to the atmosphere.",
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Selective preservation of old organic carbon fluvially released from sub-Arctic soils. / Vonk, Jorien E.; Van Dongen, Bart E.; Gustafsson, Örjan.

In: Geophysical Research Letters, Vol. 37, No. 11, L11605, 06.2010.

Research output: Contribution to JournalArticleAcademicpeer-review

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AU - Vonk, Jorien E.

AU - Van Dongen, Bart E.

AU - Gustafsson, Örjan

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AB - Amplified climate warming in the Arctic may cause thaw-remobilization of its large soil organic carbon (SOC) pool. Here we assess the remobilization and preservation of old SOC by the watershed-integrated radiocarbon signature of molecular SOC markers released from northernmost Scandinavia. The radiocarbon analyses revealed a remarkable fractionation for identical vascular plant markers (∼420‰ or ∼6000 14C years) upon settling from surface water to the underlying sediments. From this, we infer fluvial export of two SOC pools; a young surface peat component, and an old deep mineral soil component. The young pool exists as an easily degradable humic suspension, while the old pool is matrix protected from degradation and ballasted for preferential settling. The two soil types with highest OC in Arctic permafrost evidently exhibit different susceptibilities to degradation. Hence, a significant part of the thaw-released OC may simply be fluvially relocated to sediments instead of being emitted to the atmosphere.

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