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Utilization of ancient permafrost carbon in headwaters of Arctic fluvial networks.

Mann PJ, Eglinton TI, McIntyre CP, Zimov N, Davydova A, Vonk JE, Holmes RM, Spencer RG - Nat Commun (2015)

Bottom Line: Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean.Microbial demand was supported by progressively younger ((14)C-enriched) carbon downstream through the network, with predominantly modern carbon pools subsidizing microorganisms in large rivers and main-stem waters.Permafrost acts as a significant and preferentially degradable source of bioavailable carbon in Arctic freshwaters, which is likely to increase as permafrost thaw intensifies causing positive climate feedbacks in response to on-going climate change.

View Article: PubMed Central - PubMed

Affiliation: Department of Geography, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK.

ABSTRACT
Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean. Arctic warming is promoting terrestrial permafrost thaw and shifting hydrologic flowpaths, leading to fluvial mobilization of ancient carbon stores. Here we describe (14)C and (13)C characteristics of dissolved organic carbon from fluvial networks across the Kolyma River Basin (Siberia), and isotopic changes during bioincubation experiments. Microbial communities utilized ancient carbon (11,300 to >50,000 (14)C years) in permafrost thaw waters and millennial-aged carbon (up to 10,000 (14)C years) across headwater streams. Microbial demand was supported by progressively younger ((14)C-enriched) carbon downstream through the network, with predominantly modern carbon pools subsidizing microorganisms in large rivers and main-stem waters. Permafrost acts as a significant and preferentially degradable source of bioavailable carbon in Arctic freshwaters, which is likely to increase as permafrost thaw intensifies causing positive climate feedbacks in response to on-going climate change.

No MeSH data available.


Distribution of 14C and 13C isotopes and end-member contributions across the fluvial network.(a) Initial (open squares) and utilized (black circles) Δ14C and δ13C values of DOC. Isotopic ranges of three contributing carbon sources are shown in red boxes (see Methods). (b) Mean percent (±s.e.m.) contribution of each carbon source to the DOC utilized over bioincubations (DOCloss) in waters from differing site types.
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f3: Distribution of 14C and 13C isotopes and end-member contributions across the fluvial network.(a) Initial (open squares) and utilized (black circles) Δ14C and δ13C values of DOC. Isotopic ranges of three contributing carbon sources are shown in red boxes (see Methods). (b) Mean percent (±s.e.m.) contribution of each carbon source to the DOC utilized over bioincubations (DOCloss) in waters from differing site types.

Mentions: We used a dual-isotope approach26 to examine the source and age of OC subsidizing DOCloss throughout the stream network. We partitioned source contributions that most likely explained utilized Δ14C and δ13C values of DOCloss, assuming three dominant sources of DOC (contemporary terrestrial OC, permafrost-derived terrestrial OC and internally produced in situ OC) (Fig. 3a).


Utilization of ancient permafrost carbon in headwaters of Arctic fluvial networks.

Mann PJ, Eglinton TI, McIntyre CP, Zimov N, Davydova A, Vonk JE, Holmes RM, Spencer RG - Nat Commun (2015)

Distribution of 14C and 13C isotopes and end-member contributions across the fluvial network.(a) Initial (open squares) and utilized (black circles) Δ14C and δ13C values of DOC. Isotopic ranges of three contributing carbon sources are shown in red boxes (see Methods). (b) Mean percent (±s.e.m.) contribution of each carbon source to the DOC utilized over bioincubations (DOCloss) in waters from differing site types.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525200&req=5

f3: Distribution of 14C and 13C isotopes and end-member contributions across the fluvial network.(a) Initial (open squares) and utilized (black circles) Δ14C and δ13C values of DOC. Isotopic ranges of three contributing carbon sources are shown in red boxes (see Methods). (b) Mean percent (±s.e.m.) contribution of each carbon source to the DOC utilized over bioincubations (DOCloss) in waters from differing site types.
Mentions: We used a dual-isotope approach26 to examine the source and age of OC subsidizing DOCloss throughout the stream network. We partitioned source contributions that most likely explained utilized Δ14C and δ13C values of DOCloss, assuming three dominant sources of DOC (contemporary terrestrial OC, permafrost-derived terrestrial OC and internally produced in situ OC) (Fig. 3a).

Bottom Line: Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean.Microbial demand was supported by progressively younger ((14)C-enriched) carbon downstream through the network, with predominantly modern carbon pools subsidizing microorganisms in large rivers and main-stem waters.Permafrost acts as a significant and preferentially degradable source of bioavailable carbon in Arctic freshwaters, which is likely to increase as permafrost thaw intensifies causing positive climate feedbacks in response to on-going climate change.

View Article: PubMed Central - PubMed

Affiliation: Department of Geography, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK.

ABSTRACT
Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean. Arctic warming is promoting terrestrial permafrost thaw and shifting hydrologic flowpaths, leading to fluvial mobilization of ancient carbon stores. Here we describe (14)C and (13)C characteristics of dissolved organic carbon from fluvial networks across the Kolyma River Basin (Siberia), and isotopic changes during bioincubation experiments. Microbial communities utilized ancient carbon (11,300 to >50,000 (14)C years) in permafrost thaw waters and millennial-aged carbon (up to 10,000 (14)C years) across headwater streams. Microbial demand was supported by progressively younger ((14)C-enriched) carbon downstream through the network, with predominantly modern carbon pools subsidizing microorganisms in large rivers and main-stem waters. Permafrost acts as a significant and preferentially degradable source of bioavailable carbon in Arctic freshwaters, which is likely to increase as permafrost thaw intensifies causing positive climate feedbacks in response to on-going climate change.

No MeSH data available.