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Abstract:
An Amazon floodplain lake (várzea lake) was studied for its carbon content during
1981 at monthly intervals. For comparison carbon concentrations in the Amazon were
monitored during the same time. The concentrations of DOC, CO2-C and HCO3-C were
always higher in the lake than in the river. During low water the lake showed highest
concentrations for all carbon species in contrast to the river where only DOC varies seasonally.
In the river DOC reaches highest values, just before the peak flood, indicating massive transfer of DOC from the várzea into the river.
Experiments with decomposing plants showed that rotting biomass releases large
quantities of inorganic carbon (CO2-C, HCO3-C). Most of this seems to be lost to the atmosphere as evading CO2 and the amount of DOC reaching the river from the várzea
remains obscure at present.
