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| Titel |
Role of floodplains on particulate organic matter transported by the Amazon River: nature, flux and composition |
| VerfasserIn |
P. Moreira-Turcq, M. Amorim, M. Bernardes, M. P. Bonnet, M. A. P. Perez, P Seyler, J. L. Guyot |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026145
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| Zusammenfassung |
| Amazon River and its large tributaries are accompanied along their middle and lower courses
by large floodplain lakes which cover an area of about 300Â 000-500Â 000 km2. Water and
matter are constantly exchanged between river channels and floodplain lakes. The flux at
which organic matter is transferred to and from lakes such as the nature and composition
of organic matter exchanged between the two systems, and the residence time of
floodplain storage, are few known and have a special importance for the carbon cycle
in Amazon basin. The nature, composition, sources and exchange of particulate
organic matter have been studied in an Amazonian river-floodplain system during
different water periods along five years. The floodplain selected for this study was the
“Varzea do Lago Grande de Curuai” a typical floodplain of the lower Amazon River
region.
The results show that the organic matter exchanged between systems is particularly
influenced by the temporal hydrology patterns. The Amazon River organic matter was
relatively homogenous at different water periods; contrarily, the floodplain organic
matter presents a spatial and temporal variation, attesting the high complexity of this
system.
The nature of the organic matter imported by the floodplain from the River shows a very
refractory and detritical feature. On the other hand, the organic matter produced by the
floodplain and, in great portion, exported to the River is characterized by being very labile
and fresh. This organic fresh matter is mainly composed of phytoplankton and macrophytes
detritus. The organic matter produced in the floodplain can be degraded on the water column
or on the superficial sediments or exported to the Amazon River, mainly during the falling
water period, while an fraction can be buried in the floodplain mixed with the organic
refractory matter transported by the Amazon River. During the rising-high water
period, Amazonian organic matter sources are dominant in the floodplain, whereas
during the falling-low water period, autotrophic organic matter dominates in the
floodplain. Our results show that the Amazon floodplains are important sources
of young and labile particulate organic matter to the Amazon River and seem to
be a sink to the most refractory organic carbon transported by the Amazon River. |
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