Nitrogen transforming community in a horizontal subsurface-flow constructed wetland.
Constructed wetlands are important ecosystems with respect to nitrogen cycling. Here we studied the activity and abundance of nitrogen transforming bacteria as well as the spatial distribution of nitrification, anaerobic ammonium oxidation (anammox), and denitrification processes in a horizontal subsurface-flow constructed wetland. The functional genes of the nitrogen cycle were evenly distributed in a linear way along the flow path with prevalence at the superficial points. The same trend was observed for the nitrification and denitrification turnover rates using isotope labeling techniques. It was also shown that only short-term incubations should be used to measure denitrification turnover rates. Significant nitrate consumption under aerobic conditions diminishes nitrification rates and should therefore be taken into account when estimating nitrification turnover rates. This nitrate consumption was due to aerobic denitrification, the rate of which was comparable to that for anaerobic denitrification. Consequently, denitrification should not be considered as an exclusively anaerobic process. Phylogenetic analysis of hydrazine synthase (hzsA) gene clones indicated the presence of Brocadia and Kuenenia anammox species in the constructed wetland. Although anammox bacteria were detected by molecular methods, anammox activity could not be measured and hence this process appears to be of low importance in nitrogen transformations in these freshwater ecosystems.
Department of Catchment Hydrology, UFZ - Helmholtz Centre for Environmental Research, Theodor-Lieser-Str. 4, 06120 Halle/Saale, Germany. Electronic address: oksana.voloshchenko@ufz.de.
Oksana
O
Coban
Department of Environmental Biotechnology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany.
Peter
P
Kuschk
Department of Environmental Biotechnology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany.
Uwe
U
Kappelmeyer
Department of Soil Physics, UFZ - Helmholtz Centre for Environmental Research, Theodor-Lieser-Str. 4, 06120 Halle/Saale, Germany.
Oliver
O
Spott
Department of Biotechnology for Water Treatment, BTU-Cottbus-Senftenberg, Cottbus, Germany.
Marion
M
Martienssen
Department of Microbiology, Institute for Water and Wetland Research, Radboud University of Nijmegen, Nijmegen, The Netherlands.
Mike S M
MS
Jetten
Department of Catchment Hydrology, UFZ - Helmholtz Centre for Environmental Research, Theodor-Lieser-Str. 4, 06120 Halle/Saale, Germany.
Kay
K
Knoeller
D000332:Aerobiosis; D000641:Ammonia / Q000378:metabolism*; D000693:Anaerobiosis; D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D058440:Denitrification; D005798:Genes, Bacterial; D060587:Groundwater / Q000737:chemistry*; D009584:Nitrogen / Q000378:metabolism*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D014865:Waste Disposal, Fluid / Q000379:methods; D014877:Water Pollution, Chemical; D018508:Water Purification / Q000379:methods; D053833:Wetlands
D000641:Ammonia; D009584:Nitrogen
Abundance; Activity; Aerobic denitrification; Anammox; Constructed wetland; Nitrification