Efeito da disponibilidade de nitrogênio no consumo de oxigênio durante a mineralização de &lt;em&gt;Scirpus cubensis&lt;/em&gt; da Lagoa do Infernão (São Paulo, Brasil)

Lemos, Romilda Maria Alves de; Bianchini, Irineu

doi:10.4025/actascibiolsci.v29i2.524

Cited by 2 publications

(1 citation statement)

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“…According to the deoxygenation rate (k d ) it was estimated that the half-time of oxygen consumption ranged between 9 and 26 days (mineralisations of R. natans and Eleocharis sp1 e Ludwigia sp, respectively). The mean values of k d and OC MAX obtained from other mineralisation experiments of aquatic plants (Cunha and Bianchini Jr., 1998;Lemos and Bianchini Jr., 1998;Brum et al, 1999;Farjalla et al, 1999;Bitar and Bianchini Jr., 2002) were respectively 0.18 day -1 and 229 mg g -1 (DW). The k d mean value corresponds to a half-time of 4 days.…”

Section: Discussionmentioning

confidence: 89%

Oxygen uptake from aquatic macrophyte decomposition from Piraju Reservoir (Piraju, SP, Brazil)

Bianchini

Panhota

2011

Braz. J. Biol.

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The kinetics of oxygen consumption related to mineralisation of 18 taxa of aquatic macrophytes (Cyperus sp, Azolla caroliniana, Echinodorus macrophyllus, Eichhornia azurea, Eichhornia crassipes, Eleocharis sp1, Eleocharis sp2, Hetereanthera multiflora, Hydrocotyle raniculoides, Ludwigia sp, Myriophyllum aquaticum, Nymphaea elegans, Oxycaryum cubense, Ricciocarpus natans, Rynchospora corymbosa, Salvinia auriculata, Typha domingensis and Utricularia foliosa) from the reservoir of Piraju Hydroelectric Power Plant (São Paulo state, Brazil) were described. For each species, two incubations were prepared with ca. 300.0 mg of plant (DW) and 1.0 L of reservoir water sample. The incubations were maintained in the dark and at 20 ºC. Periodically the dissolved oxygen (DO) concentrations were measured; the accumulated DO values were fitted to 1st order kinetic model and the results showed that: i) high oxygen consumption was observed for Ludwigia sp (533 mg g-1 DW), while the lowest was registered for Eleocharis sp1 (205 mg g-1 DW) mineralisation; ii) the higher deoxygenation rate constants were verified in the mineralisation of A. caroliniana (0.052 day-1), H. raniculoides (0.050 day-1) and U. foliosa (0.049 day-1). The oxygen consumption rate constants of Ludwigia sp and Eleocharis sp2 mineralisation (0.027 day-1) were the lowest. The half-time of oxygen consumption varied from 9 to 26 days. In the short term, the detritus of E. macrophyllus, H. raniculoides, Ludwigia sp, N. elegans and U. foliosa were the critical resources to the reservoir oxygen demand; while in the long term, A. caroliniana, H. multiflora and T. domingensis were the resources that can potentially contribute to the benthic oxygen demand of this reservoir.

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Section: Discussionmentioning

confidence: 89%

Oxygen uptake from aquatic macrophyte decomposition from Piraju Reservoir (Piraju, SP, Brazil)

Bianchini

Panhota

2011

Braz. J. Biol.

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Effects of nitrate enrichment on leaf litter decomposition

Tonin¹,

Hepp²

2011

Acta

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Aim: This study aimed to determine the effects of nitrate enrichment on leaf decomposition process and the kinetic parameters of decomposition model; Methods: Samples of water from a first-order stream and senescent leaves of the native tree species Campomanesia xanthocarpa O. Berg (Myrtaceae) were collected in South of Brazil. The leaves were oven-dried, grounded and for each experimental condition (control and enriched) 20 decomposition chambers were prepared with leaf fragments and unfiltered stream water (with and without nitrate addition), maintained under low and high oxygen conditions. In sampling days the particulate and dissolved organic carbon and total inorganic carbon concentrations were evaluated; Results: The decomposition of particulate and dissolved organic carbon (POC and DOC) was faster in nitrate enriched treatment under high dissolved oxygen condition. The DOC mineralization coefficients (k 3 ) were in average 283-fold higher than the rate constants for refractory POC (RPOC) mineralization, being the enriched k 3 2.3-fold higher than the control k 3 ; Conclusions: The leaf litter decomposition was affected by dissolved nitrate concentration in the water and RPOC and DOC decomposition was faster with nitrate enrichment than in reference natural conditions (without nitrate enrichment). Thus, dissolved nitrate seems to be an important factor in controlling litter decomposition and its increase affects the leaf carbon processing in stream ecosystems.Keywords: nutrients, kinetic model, organic carbon, eutrophication.Resumo: Objetivo: Esse estudo tem por objetivo determinar os efeitos do enriquecimento por nitrato sobre o processo de decomposição foliar e os parâmetros cinéticos do modelo de decomposição; Métodos: Foram coletadas amostras de água de um riacho de primeira-ordem e folhas senescentes da espécie arbórea nativa Campomanesia xanthocarpa O. Berg (Myrtaceae) no sul do Brasil. As folhas foram secas em estufa, moídas e para cada condição experimental (controle e enriquecido), 20 câmaras de decomposição foram preparadas com fragmentos foliares e água não filtrada do riacho (com e sem adição de nitrato), mantidas sobre condições de baixa e alta oxigenação. Nos dias amostrais, as concentrações de carbono orgânico particulado e dissolvido e, carbono inorgânico total foram avaliadas; Resultados: A decomposição do carbono orgânico particulado e dissolvido (COP e COD) foi mais acelerada no tratamento enriquecido com nitrato e sob a condição de alta oxigenação. O coeficiente de mineralização do COD (k 3 ) foi em média 283 vezes maior que as taxas de mineralização das frações de carbono orgânico particulado refratário (COPR), sendo o k 3 do meio enriquecido 2,3 vezes maior que o k 3 do controle; Conclusões: A decomposição dos detritos foliares foi afetada pela concentração de nitrato dissolvido na água e as decomposições do COPR e COD foram mais aceleradas com o enriquecimento por nitrato que em condições naturais de referência (sem enriquecimento por nitrato). Assim, o nitrato dissolvido m...

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Efeito da disponibilidade de nitrogênio no consumo de oxigênio durante a mineralização de <em>Scirpus cubensis</em> da Lagoa do Infernão (São Paulo, Brasil)

Cited by 2 publications

References 4 publications

Oxygen uptake from aquatic macrophyte decomposition from Piraju Reservoir (Piraju, SP, Brazil)

Oxygen uptake from aquatic macrophyte decomposition from Piraju Reservoir (Piraju, SP, Brazil)

Effects of nitrate enrichment on leaf litter decomposition

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