Sediment Denitrification in Two Contrasting Tropical Shallow Lagoons.

Published in Estuaries and Coasts, v. 39(3):657-663 
Authors

Enrich-Prast, A., Santoro, A.L., Coutinho, R.S., Nielsen, L.P. and Esteves, F.A.
Publication year 2016
DOI https://doi.org/10.1007/s12237-015-0017-5 
Affiliations
  • Laboratório de Biogeoquímica, Departamento de Ecologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, (RJ) 21941-971, Brazil
  • Department of Environmental Change, Linköping University, 581, 83 Linköping, Sweden
  • Laboratório de Limnologia, Departamento de Ecologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, (RJ) 21941-971, Brazil
  • Department of Biology, University of Aarhus, Ny Munkegade 114, DK8000 Aarhus C, Denmark
  • Núcleo de Pesquisas em Ecologia e Desenvolvimento Sócio-ambiental de Macaé - NUPEM, Universidade Federal do Rio de Janeiro - UFRJ, Av. Rotary Club, s/n, Macaé, RJ CEP 28970-000, São José do Barreto, Brazil
IAI Program

CRN3
IAI Project CRN3038
Keywords
Nitrogen
Denitrification
Oxygen consumption
Sediment
Tropical
Coastal lagoons

Abstract

Sediment denitrification was monthly evaluated in two tropical coastal lagoons with different trophic states using the 15N isotope pairing technique. Denitrification rates were very low in both environments, always <5.0 &mumol N2 m&minus2 h&minus1 and were not significantly different between them. Oxygen consumption varied from 426 to 4248 &mumol O2 m&minus2 h&minus1 and was generally three times higher in the meso-eutrophic than the oligotrophic lagoon. The low denitrification activity was ascribed to both low water NO3- concentrations (<2.0 &muM) and little nitrate supply from nitrification. There was no correlation of denitrification with nitrate or ammonium fluxes. Sediments in temperate environments with similar oxygen consumption rates usually presented a higher proportion of nitrification&ndashdenitrification rates. Sediment oxygen consumption was a good predictor of sediment denitrification in both studied lagoons.