Abstract
Decomposition experiments were performed using the closed bottles method and seven aquatic macrophytes: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Salvinia auriculata, Oxycaryum cubense and Utricularia breviscapa. Cultures with lagoon water and macrophytes detritus were incubated at 20 °C under aerobic conditions. Total particulate and dissolved organic carbon and dissolved oxygen concentrations were analyzed. The major findings were: (i) the maximum amount of consumed oxygen (OC MAX) and deoxigenation rates ( k d) differ among macrophyte decays (OC MAX: 165–700 mg g −1 DW; k d: 0.014–0.045 d −1); these differences depends mainly on molecular and elemental composition of detritus; in short period, the cytoplasm fraction of detritus enhanced the catabolic activity; (ii) the kinetic model adopted to describe the oxygen consumption was shown appropriate; the parameter more affected by the chemical differences of detritus was OC MAX; the constant rates of oxygen consumption ( k d) were relatively smaller in relation to obtained to oxidative decarboxylation processes (ca. 6 times) and presented minimum changes if compared with the detritus variations.
Published Version
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