Oxygen demand during mineralization of aquatic macrophytes from an oxbow lake

Abstract

This study presents a kinetic model of oxygen consumption during aerobic decomposition of detritus from seven species of aquatic macrophytes: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Salvinia auriculata, Oxycaryum cubense and Utricularia breviscapa. The aquatic macrophytes were collected from Óleo Lagoon situated in the Mogi-Guaçu river floodplain (SP, Brazil). Mineralization experiments were performed using the closed bottles method. Incubations made with lake water and macrophytes detritus (500 mL and 200 mg.L -1 (DM), respectively) were maintained during 45 to 80 days at 20 °C under aerobic conditions and darkness. Carbon content of leachates from aquatic macrophytes detritus and dissolved oxygen concentrations were analyzed. From the results we concluded that: i) the decomposition constants differ among macrophytes; these differences being dependent primarily on molecular and elemental composition of detritus and ii) in the short term, most of the oxygen demand seems to depend upon the demineralization of the dissolved carbon fraction.Keywords: aquatic macrophytes, oxygen uptake, oxbow lake and kinetic. Demanda de oxigênio durante a mineralização de macrófitas aquáticas de uma lagoa marginal ResumoNesse estudo foi utilizado um modelo cinético para a descrição dos consumos de oxigênio durante a mineralização aeróbia de detritos de sete espécies de macrófitas aquáticas: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Salvinia auriculata, Oxycaryum cubense e Utricularia breviscapa. As macrófitas aquáticas foram coletadas na Lagoa do Óleo, situada na planície de inundação do rio Mogi-Guaçu (SP, Brasil). Os experimentos foram realizados empregando-se incubações similares as de DBO. As incubações foram preparadas com água da lagoa e detritos das macrófitas aquáticas (500 mL e 200 mg.L -1 (PS), respectivamente) e foram mantidas durante 45 a 80 dias a 20 °C, sob condições aeróbias e no escuro. Foram determinados os conteúdos de carbono dos lixiviados dos detritos e os consumos de oxigênio dissolvido durante a mineralização. A partir dos resultados obtidos pôde-se concluir que: i) os coeficientes de mineralização das macrófitas aquáticas diferiram entre si, essas diferenças dependeram principalmente das composições moleculares e elementares dos detritos; e ii) a curto prazo, grande parte da demanda de oxigênio parece depender da mineralização das de carbono dissolvido provenientes da lixiviação.Palavras-chave: macrófitas aquáticas, consumo de oxigênio, lagoa marginal e cinética.

Limnology in the Upper Paraná River floodplain: large-scale spatial and temporal patterns, and the influence of reservoirs

“…This process occurs mainly during low-water periods, and is common in lakes of many river-floodplain systems (Esteves et al, 1994;Carvalho et al, 2001). Fertilization during high-water periods may also occur from river contribution and/or plant biomass decomposition, what also decreases oxygen in water column (Camargo and Esteves, 1995;Pagioro and Thomaz, 1999;Taniguchi et al, 2004;Thomaz et al, 2004;Bianchini Jr. et al, 2008). However, in the Paraná floodplain fertilization from rivers during floods is important only habitats connected to the Baía and Ivinheima rivers, which carry more nutrients than the Paraná River (see " Long-term trends", below).…”

Estimating nitrogen and phosphorus saturation point for Eichhornia crassipes (Mart.) Solms and Salvinia molesta Mitchell in mesocosms used to treating aquaculture effluent

“…The aquatic macrophytes affect nutrient cycle through active and passive transfers of chemical elements from sediment to water (Camargo et al, 2003). The relatively slow decomposition of fibrous material of macrophytes (e.g., cellulose, lignin and hemicellulose) also contributes to the return of carbon to sediment (Bianchini Junior et al, 2008;Bianchini Junior et al, 2010;Thomaz and Esteves, 2011).…”

Plankton diversity and limnological characterization in two shallow tropical urban reservoirs of Pernambuco State, Brazil

“…Concerning floating macrophytes, their development can cause problems by disease vectors dispersion (Kengne et al 2003) and reduction in the oxygen levels by decomposition (Bianchini Jr et al 2008).…”

“…ALMEIDA , MARIA DA GRAÇA G. MELÃO and ARIADNE N. MOURA the oxygen demands for the oxidation of carbon and freeing of nutrients (Bianchini Jr et al 2008). High values for suspended solids (SS) in Apipucos reservoir must be related to low water transparency in this water body since, according to Malmaeus and Hakanson (2003), SS have an influence in the Secchi disc depth.…”