caa a22 4500 386380406 CHVBK 20180307112039.0 cr unu---uuuuu 161130e198908 xx s 000 0 eng 10.1017/S0266467400003710 doi S0266467400003710 pii (NATIONALLICENCE)cambridge-10.1017/S0266467400003710 Short term nitrogen dynamics in a small Brazilian wetland (Lago Infernão, São Paulo) [Elektronische Daten] We have studied a number of related processes of the nitrogen cycle in a Brazilian floodplain lake to identify the major pools and pathways over a short time period. The study was centred on the littoral zone dominated by the floating plant Eichhornia azurea, which has a large epiphyte algal community of which heterocystous cyanobacteria were the major components. The water column was continuously undersaturated with oxygen although some elevated values (to 60% saturation) were recorded in the macrophyte beds in the afternoon. Marked diel temperature changes were documented. NH4-N dominated the dissolved N component in the water with maximal values (60 mg m−3) at lowest O2, concentrations early in the morning. Nitrogen fixation (acetylene reduction) of the epiphyte community showed marked diel changes with daily values of 5 mg N fixed m−2 day−1 (based on 3:1 C2H4:N2 ratio). Macrophyte NH4-N uptake rates (in situ incubations) were 93 mg N m−2 day−1. The activities of nitrifying bacteria could not be detected with the nitrapyrin block on dark CO2 fixation but denitrification (acetylene block technique) was recorded in the sediments when enhanced with NO- 3. The major pathways of aquatic nitrogen involved macrophyte uptake and sediment release of NH4-N. Copyright © Cambridge University Press 1989 aquatic macrophyte nationallicence Brazil nationallicence denitrification nationallicence littoral zone nationallicence nitrification nationallicence nitrogen fixation nationallicence wetland nationallicence Howard-Williams Clive Taupo Research Laboratory, DSIR, PO Box 415, Taupo, New Zealand de Esteves F. Federal University of São Carlos, São Carlos, SP. Brasil Santos J. E. Federal University of São Carlos, São Carlos, SP. Brasil Downes M. T. Taupo Research Laboratory, DSIR, PO Box 415, Taupo, New Zealand Journal of Tropical Ecology Cambridge University Press 5/3(1989-08), 323-335 0266-4674 5:3<323 1989 5 TRO https://doi.org/10.1017/S0266467400003710 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0266467400003710 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Howard-Williams Clive Taupo Research Laboratory, DSIR, PO Box 415, Taupo, New Zealand NATIONALLICENCE 700 1- de Esteves F. Federal University of São Carlos, São Carlos, SP. Brasil NATIONALLICENCE 700 1- Santos J. E. Federal University of São Carlos, São Carlos, SP. Brasil NATIONALLICENCE 700 1- Downes M. T. Taupo Research Laboratory, DSIR, PO Box 415, Taupo, New Zealand NATIONALLICENCE 773 0- Journal of Tropical Ecology Cambridge University Press 5/3(1989-08), 323-335 0266-4674 5:3<323 1989 5 TRO CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge