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| Titel |
Multi-molecular tracers of terrestrial carbon transfer across the pan-Arctic: comparison of hydrolyzable components with plant wax lipids and lignin phenols |
| VerfasserIn |
X. Feng, Ö. Gustafsson, R. M. Holmes, J. E. Vonk, B. E. van Dongen, I. P. Semiletov, O. V. Dudarev, M. B. Yunker, R. W. Macdonald, D. B. Montluçon, T. I. Eglinton |
| 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. 15 ; Nr. 12, no. 15 (2015-08-14), S.4841-4860 |
| Datensatznummer |
250118062
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| Publikation (Nr.) |
 copernicus.org/bg-12-4841-2015.pdf |
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| Zusammenfassung |
| Hydrolyzable organic carbon (OC) comprises a significant component of
sedimentary particulate matter transferred from land into oceans via rivers.
Its abundance and nature are however not well studied in Arctic river
systems, and yet may represent an important pool of carbon whose fate
remains unclear in the context of mobilization and related processes
associated with a changing climate. Here, we examine the molecular composition
and source of hydrolyzable compounds isolated from sedimentary particles
derived from nine rivers across the pan-Arctic. Bound fatty acids (b-FAs),
hydroxy FAs, n-alkane-α,ω-dioic acids (DAs) and phenols were
the major components released upon hydrolysis of these sediments. Among
them, b-FAs received considerable inputs from bacterial and/or algal
sources, whereas ω-hydroxy FAs, mid-chain substituted acids, DAs,
and hydrolyzable phenols were mainly derived from cutin and suberin of
higher plants. We further compared the distribution and fate of suberin- and
cutin-derived compounds with those of other terrestrial biomarkers (plant
wax lipids and lignin phenols) from the same Arctic river sedimentary
particles and conducted a benchmark assessment of several biomarker-based
indicators of OC source and extent of degradation. While suberin-specific
biomarkers were positively correlated with plant-derived
high-molecular-weight (HMW) FAs, lignin phenols were correlated with
cutin-derived compounds. These correlations suggest that, similar to
leaf-derived cutin, lignin was mainly derived from litter and surface soil
horizons, whereas suberin and HMW FAs incorporated significant inputs from
belowground sources (roots and deeper soil). This conclusion is supported by
the negative correlation between lignin phenols and the ratio of
suberin-to-cutin biomarkers. Furthermore, the molecular composition of
investigated biomarkers differed between Eurasian and North American Arctic
rivers: while lignin dominated in the terrestrial OC of Eurasian river
sediments, hydrolyzable OC represented a much larger fraction in the
sedimentary particles from Colville River. Hence, studies exclusively
focusing on either plant wax lipids or lignin phenols will not be able to
fully unravel the mobilization and fate of bound OC in Arctic rivers.
More comprehensive, multi-molecular investigations are needed to better
constrain the land–ocean transfer of carbon in the changing Arctic,
including further research on the degradation and transfer of both free and
bound components in Arctic river sediments. |
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