CONTRIBUTION TO DISSOLVED ORGANIC MATTER BY DECOMPOSITION OF AQUATIC MACROPHYTES, EICHHORNIA AZUREA.

Abstract

Organic matter plays a fundamental role in many ecological processes and decomposition is among the main cycling routes of organic matter. The decomposition of aquatic macrophytes generates much debris, since the carbon of these algae is not easily assimilated by other organisms. Spectroscopic analyses are important in organic matter studies, because it enables satisfactory distinction between labile and refractory materials can be obtained. Through comparing the fluorescence spectrum of the organic debris generated by a decomposing macrophyte with those of water, sediment, and soil samples from the Upper Parana River fl oodplain water bodies, we were able to estimate the contribution of decomposition to local carbon cycles. The results revealed a higher contribution of decomposition to the oligotrophic environments connected with the Parana River, while some water bodies connected with the rivers Ivinheima and Baia showed a greater participation of allochthonous organic matter, mainly derived from humus.