Emissions of methane and carbon dioxide during anaerobic decomposition of aquatic macrophytes from a tropical lagoon (São Paulo, Brazil)

Abstract

Emissões de metano e dióxido de carbono da decomposição de macrófitas aquáticas de uma lagoa tropical (São Paulo, Brasil) Irineu Bianchini Jr. 4 and CO 2 emissions in floodplain lakes. To examine this connection, this study measured CO 2 and CH 4 formation during anaerobic decomposition of aquatic macrophytes from a floodplain lake; Methods: Methane formation was determined to the intrinsic characteristics of the debris, and the experimental (physical and chemical) conditions. Production of CH 4 and CO 2 were measured during anaerobic degradation of seven aquatic macrophytes: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Ludwigia inclinata, Oxycaryum cubense, and Utricularia breviscapa, all of which inhabit the littoral zone of the lagoon studied; Results: Overall, methanogenesis was more sensitive to temperature variation than gross anaerobic mineralization. Although the metabolic routes that generate CO 2 were always predominant, as a competing process methanogenesis was favored by increasing temperature to the detriment of CO 2 formation. Although several factors (such as pH, redox potential, salinity and nutrients availability) influenced yields of the final degradation products, temperature and detritus chemical composition were, in a first approach, the key factors in CH 4 formation. In the oxbow lakes of the Mogi-Guaçu River Floodplain, especially Óleo Lagoon, on average, 10% of the total carbon can be regarded as the yield of CH 4 formation derived from aquatic macrophyte decay, while the remaining carbon (90%) became CO 2 .Keywords: methane, anaerobic decomposition, aquatic macrophytes, wetland, floodplain lakes, Mogi-Guaçu River, Óleo Lagoon.Resumo: Objetivo: Acúmulos intensos de plantas nos sedimentos são importantes fontes de emissões de CH 4 e CO 2 em lagoas de várzea de inundação. Nesse estudo foram determinadas as formações de CH 4 e CO 2 da decomposição anaeróbia de macrófitas aquáticas de uma lagoa marginal; Métodos: A formação do metano foi determinada com base nas características intrínsecas dos detritos e das condições experimentais. As produções de CH 4 e CO 2 foram determinadas durante a degradação de sete espécies de macrófitas aquáticas: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Ludwigia inclinata, Oxycaryum cubense, and Utricularia breviscapa, todas provenientes da zona litorânea da lagoa marginal selecionada; Resultados: De modo geral, a mentanogênese foi mais sensível à variação da temperatura que os demais processos de mineralização. Embora as rotas metabólicas que geraram o CO 2 sempre predominaram, a formação do metano foi favorecida com o incremento da temperatura em detrimento da geração de CO 2 . Enquanto vários fatores (e.g. pH, potencial redox, salinidade, disponibilidade de nutrientes) influenciaram os rendimentos dos produtos finais da degradação, a temperatura e a composição química dos detritos foram, de modo geral, os fatores mais importantes para a formação do CH 4 . Nas lagoas marginais da várzea de inundação do rio ...

Seasonal Variability of Tropical Wetland CH<sub>4</sub> emissions: the role of the methanogen-available carbon pool

“…These observations showed a rapid decrease in decomposition rates over the incubation period. Bianchini Jr. et al (2010) found similar results for anaerobic decomposition from dried and ground Oxycaryum cubense at 20 • C: following a 20-day lag (where no emissions were observed) CH 4 produced from organic carbon decomposition peaked after a 50-day period, and then rapidly decreased. On a tropical river-basin scale, flooded areas expand at the onset of the wet season and engulf newly available plant litter; as a result, CH 4 emissions from plant litter may peak before the height of the water table.…”

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).…”

“…Several authors have evaluated the growth of aquatic macrophytes under different nutrient concentrations and demonstrated that higher concentrations provide faster growth and higher final biomass (Bini et al, 1999;Camargo et al, 2003;Thomaz et al, 2007;Bianchini Junior et al, 2010). However, few studies have sought to assess the nutrient concentrations in which an aquatic macrophyte reaches maximum growth.…”

Molecular changes of aquatic humic substances formed from four aquatic macrophytes decomposed under different oxygen conditions

“…The HA from E. najas were also related to more aliphatic content, but under aerobic conditions a decrease in the aliphatic content was observed ( Figure 5). This might be related to lower cell wall fraction and lignin content than the other plants [41][42][43][44][45].…”