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| Titel |
Characterization of particulate organic matter in the Lena River delta and adjacent nearshore zone, NE Siberia – Part 2: Lignin-derived phenol compositions |
| VerfasserIn |
M. Winterfeld, M. A. Goñi, J. Just, J. Hefter, G. Mollenhauer |
| 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. 7 ; Nr. 12, no. 7 (2015-04-15), S.2261-2283 |
| Datensatznummer |
250117900
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| Publikation (Nr.) |
 copernicus.org/bg-12-2261-2015.pdf |
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| Zusammenfassung |
| The Lena River in central Siberia is one of the major pathways translocating
terrestrial organic matter (OM) from its vast catchment area to the coastal
zone of the Laptev Sea and the Arctic Ocean. The permafrost soils of its far south-stretching catchment, which store huge amounts of OM, will most likely
respond differently to climate warming and remobilize previously frozen OM
with distinct properties specific for the source vegetation and soil. To
characterize the material discharged by the Lena River, we analyzed the
lignin phenol composition in total suspended matter (TSM) from surface water
collected in spring and summer, surface sediments from Buor Khaya Bay
along with soils from the Lena Delta's first (Holocene) and third terraces
(Pleistocene ice complex), and plant samples. Our results show that
lignin-derived cinnamyl : vanillyl (C / V) and syringyl : vanillyl (S / V) ratios
are > 0.14 and 0.25, respectively, in TSM and surface sediments,
whereas in delta soils they are > 0.16 and > 0.51,
respectively. These lignin compositions are consistent with significant
inputs of organic matter from non-woody angiosperm sources mixed with
organic matter derived from woody gymnosperm sources. We applied a simple
linear mixing model based on the C / V and S / V ratios, and the results indicate
the organic matter in delta TSM samples and Buor Khaya Bay surface sediments
contain comparable contributions from gymnosperm material, which is
primarily derived from the taiga forests south of the delta, and angiosperm
material typical for tundra vegetation. Considering the small catchment area
covered by tundra (~ 12%), the input is substantial and
tundra-derived OM input is likely to increase in a warming Arctic. The
similar and high acid to aldehyde ratios of vanillyl and syringyl
(Ad / AlV, S) in Lena Delta summer TSM (> 0.7 and > 0.5, respectively) and Buor Khaya Bay surface sediments (> 1.0
and > 0.9, respectively) suggest that the OM is highly degraded
and Lena River summer TSM could be a possible source of the surface
sediments. The Ad / AlV, S ratios of the first and third delta terraces
were generally lower (mean ratios > 0.4 and > 0.4,
respectively) than summer TSM and surface sediments. This implies that TSM
contains additional contributions from a more degraded OM source (southern
catchment and/or finer more degraded particle size). Alternatively, OM
degradation on land after permafrost thawing and subaqueously during
transport and sedimentation could be considerable. Despite the high natural
heterogeneity of OM stored in delta soils and exported by the Lena River,
the catchment-characteristic vegetation is reflected by the lignin biomarker
composition. Climate-warming-related changes in the Lena River catchment may
be detectable in changing lignin biomarker composition and diagenetic
alteration. |
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