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Título: Seasonal denitrification in flooded and exposed sediments from the Amazon floodplain at Lago Camaleão
Autor(es): J. KERN
FURCH, Karin
W J Junk
Assad José Darwich
ISSN: 0095-3628
Revista: Microbial Ecology
Volume: 32
Resumo: Denitrification processes were measured by the acetylene-block- age technique under changing flood conditions along the aquatic/terrestrial transition zone on the Amazon floodplain at Lago Camale~o, near Manaus, Brazil. In flooded sediments, denitrification was recorded after the amendment with NO3- (100 txmol liter <) throughout the whole study period from August 1992 to February 1993. It ranged from 192,3 to 640.7 fxmol N m -2 h -1 in the 0- to 5-cm sediment layer. Without substrate amendment, denitrification was detected only during low water in November and December 1992, when it occurred at a rate of up to 12.2 ~xmol N m -2 h -~. Higher rates of denitrification at an average rate of 73.3 Ixmol N m -2 h -~ were measured in sediments from the shallow lake basin that were exposed to air at low water. N20 evolution was never detected in flooded sediments, but in exposed sediments, it was detected at an average rate of 28.3 Ixmol N m -2 h -~ during the low-water period. The results indicate that under natural conditions there is denitrification and hence a loss in nitrogen from the Amazon floodplain to the atmosphere. Rates of denitrification in flooded sediments were one to two orders of magni- tude smaller than in temperate regions. However, the nitrogen removal of exposed sediments exceeded that of undisturbed wetland soils of temperate regions, indicating a considerable impact of the flood pulse on the gaseous turnover of nitrogen in the Amazon floodplain.
ISSN: 0095-3628
Aparece nas coleções:Coordenação de Biodiversidade (CBIO)

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