THE RELEASE PATHWAYS OF CARBON FROM DETRITUS OF AQUATIC MACROPHYTES

Abstract

Herein, processes linked to the release of the carbon (e.g. CO2, CH4, DOC) from decomposition of aquatic macrophytes are discussed. A brief compilation of other studies was made to verify the variation of carbon contents in the plant tissues, and carbon mineralization processes were discussed in face of the conditioning factors that usually operate at continental aquatic systems (e.g. temperature, availability of dissolved oxygen). A kinetic model was proposed to describe and compare the rate of mineralization of released detritus. The mineralization generally follows three different pathways, each one involving different amounts of carbon. The predominant pathway -- oxidation of particulate refractory organic compounds, like fibers -- is the slowest pathway, with a mean half-time of 88 days. The mineralization of soluble and labile organic compounds seem to involve less carbon (ca. 29.7%), and takes place faster.