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| Titel |
The composition and flux of particulate and dissolved carbohydrates from the Rhone River into the Mediterranean Sea |
| VerfasserIn |
C. Panagiotopoulos, R. Sempéré, J. Para, P. Raimbault, C. Rabouille, B. Charrière |
| 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 ; 9, no. 5 ; Nr. 9, no. 5 (2012-05-24), S.1827-1844 |
| Datensatznummer |
250007032
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| Publikation (Nr.) |
 copernicus.org/bg-9-1827-2012.pdf |
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| Zusammenfassung |
Carbohydrates are important components of the carbon cycle and may be used
as indicators of the origin and the diagenetic status of marine and
terrestrial organic matter. Nevertheless, comprehensive studies of both
particulate (PCHO) and dissolved (DCHO) carbohydrates in rivers are scarce,
and the seasonal and interannual variability of these compounds in
relationship to the bulk particulate (POM) and dissolved organic matter
(DOM) is largely unknown. For the period 2007–2009, we sampled once per
month POM and DOM and measured the total suspended matter (TSM), POM, DOM,
PCHO, and DCHO for the Rhône River, which flows into the Mediterranean
Sea. Using these measurements, we estimated for the above parameters annual
fluxes for the period 2007–2009. The estimated carbohydrate fluxes averaged
0.064 ± 0.026 × 1010 moles C yr−1 for PCHO and
0.042 ± 0.008 × 1010 moles C yr−1 DCHO, representing 6 %
and 7 % of the annual flux of POC and DOC, respectively. During flood and
low-water periods, POM variations were reflected into the PCHO pool, whereas
this was not observed for DOC and DCHO, indicating a decoupling between
particulate and dissolved organic matter. Our results also showed that flood
and low-water periods may be differentiated using the ratios PCHO/DCHO and
POC/DOC, which had a significant relationship.
Based on the carbohydrate abundances in both the PCHO and DCHO pools, we
conclude that this material mainly derives from allochthonous sources
(vascular plants, bacteria and soils). Moreover, during flood events, an
enrichment in mannose in POM was observed, probably reflecting an angiosperm
source (leaves or grasses). By expanding our results to the northwestern
Mediterranean Sea (Gulf of Lions), we found that the total organic carbon
(TOC) fluxes of the Rhône River accounted for ~1 % of the
standing stock of seawater TOC. Considering that glucose is the most
abundant carbohydrate in both particulate and dissolved organic matter pools
(~33 %), its annual flux in the northwestern Mediterranean Sea was
estimated to 3.8 × 108 moles glucose. |
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