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| Titel |
Biodegradability of dissolved organic carbon in permafrost soils and aquatic systems: a meta-analysis |
| VerfasserIn |
J. E. Vonk, S. E. Tank, P. J. Mann, R. G. M. Spencer, C. C. Treat, R. G. Striegl, B. W. Abbott, K. P. Wickland |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 23 ; Nr. 12, no. 23 (2015-12-03), S.6915-6930 |
| Datensatznummer |
250118190
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| Publikation (Nr.) |
 copernicus.org/bg-12-6915-2015.pdf |
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| Zusammenfassung |
As Arctic regions warm and frozen soils thaw, the large organic carbon pool
stored in permafrost becomes increasingly vulnerable to decomposition or
transport. The transfer of newly mobilized carbon to the atmosphere and its
potential influence upon climate change will largely depend on the
degradability of carbon delivered to aquatic ecosystems. Dissolved organic
carbon (DOC) is a key regulator of aquatic metabolism, yet knowledge of the
mechanistic controls on DOC biodegradability is currently poor due to a
scarcity of long-term data sets, limited spatial coverage of available data,
and methodological diversity. Here, we performed parallel biodegradable DOC
(BDOC) experiments at six Arctic sites (16 experiments) using a standardized
incubation protocol to examine the effect of methodological differences
commonly used in the literature. We also synthesized results from 14 aquatic
and soil leachate BDOC studies from across the circum-arctic permafrost
region to examine pan-arctic trends in BDOC.
An increasing extent of permafrost across the landscape resulted in higher
DOC losses in both soil and aquatic systems. We hypothesize that the unique
composition of (yedoma) permafrost-derived DOC combined with limited prior
microbial processing due to low soil temperature and relatively short flow
path lengths and transport times, contributed to a higher overall
terrestrial and freshwater DOC loss. Additionally, we found that the
fraction of BDOC decreased moving down the fluvial network in continuous
permafrost regions, i.e. from streams to large rivers, suggesting that
highly biodegradable DOC is lost in headwater streams. We also observed a
seasonal (January–December) decrease in BDOC in large streams and rivers, but saw
no apparent change in smaller streams or soil leachates. We attribute this
seasonal change to a combination of factors including shifts in carbon
source, changing DOC residence time related to increasing thaw-depth,
increasing water temperatures later in the summer, as well as decreasing
hydrologic connectivity between soils and surface water as the thaw season
progresses. Our results suggest that future climate warming-induced shifts
of continuous permafrost into discontinuous permafrost regions could affect
the degradation potential of thaw-released DOC, the amount of BDOC, as well
as its variability throughout the Arctic summer. We lastly recommend a
standardized BDOC protocol to facilitate the comparison of future work and
improve our knowledge of processing and transport of DOC in a changing
Arctic. |
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