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Nitrogen processing in a tidal freshwater marsh: a whole-ecosystem 15N labeling study
Gribsholt, B.; Boschker, H.T.S.; Struyf, E.; Andersson, M.; Tramper, A.; De Brabandere, L.; Van Damme, S.; Brion, N.; Meire, P.; Dehairs, F.; Middelburg, J.J.; Heip, C.H.R. (2005). Nitrogen processing in a tidal freshwater marsh: a whole-ecosystem 15N labeling study. Limnol. Oceanogr. 50(6): 1945-1959. dx.doi.org/10.4319/lo.2005.50.6.1945
In: Limnology and Oceanography. American Society of Limnology and Oceanography: Waco, Tex., etc.. ISSN 0024-3590, more
Peer reviewed article  

Available in  Authors | Datasets 
    VLIZ: Open Repository 75814 [ OMA ]

Keywords
    Estuaries; Intertidal environment; Marshes; Nitrogen cycle; Particulate organic nitrogen; Radioactive labelling; Belgium, Durme R. [Marine Regions]; Belgium, Zeeschelde [Marine Regions]; Fresh water

Authors  Top | Datasets 
  • Gribsholt, B., more
  • Boschker, H.T.S., more
  • Struyf, E., more
  • Andersson, M., more
  • Tramper, A., more
  • De Brabandere, L., more

Abstract
    We quantified the fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River in a whole-ecosystem 15N labeling experiment. 15N-NH4+ was added to the floodwater entering a 3,477 m² tidal marsh area, and marsh ammonium processing and retention were traced in six subsequent tide cycles. We present data for the water phase components of the marsh system, in which changes in concentration and isotopic enrichment of NO3-, NO2-, N2O, N2, NH4+, and suspended particulate nitrogen (SPN) were measured in concert with a mass balance study. Simultaneous addition of a conservative tracer (NaBr) confirmed that tracer was evenly distributed, and the Br- budget was almost closed (115% recovery). All analyzed dissolved and suspended N pools were labeled, and 31% of added 15N-NH4+ was retained or transformed. Nitrate was the most important pool for 15N, with nitrification accounting for 30% of 15N -transformation. In situ whole-ecosystem nitrification rates were four to nine times higher than those in the water column alone, implying a crucial role for the large reactive marsh surface area in N-transformation. Under conditions of low oxygen concentrations and high ammonium availability, nitrifiers produced N2O. Our results show that tidal freshwater marshes function not only as nutrient sinks but also as nutrient transformers.

Datasets (2)
  • Nevlas (02MM19): Carbon and nitrogen cycling in the Western Scheldt, The Netherlands, more
  • N-Schor: Whole ecosystem 15N labelling study in the Scheldt, more

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