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Methane and nitrous oxide in tidal estuaries
Middelburg, J.J.; de Bie, M.J.M.; Nieuwenhuize, J. (2002). Methane and nitrous oxide in tidal estuaries, in: ECSA Local Meeting: ecological structures and functions in the Scheldt Estuary: from past to future, Antwerp, Belgium October 7-10, 2002: abstract book. pp. 22
In: (2002). ECSA Local Meeting: Ecological structures and functions in the Scheldt Estuary: from past to future, Antwerp, Belgium October 7-10, 2002: abstract book. University of Antwerp: Antwerp. 73 + 1 cd-rom pp.
Available in  Authors 
    Vlaams Instituut voor de Zee: Open access 126916 [ download pdf ]
Document type: Conference paper
Keywords
    ANE, British Isles, England, Thames Estuary
    Belgium, Schelde R.
    Chemical compounds > Organic compounds > Hydrocarbons > Saturated hydrocarbons > Acyclic hydrocarbons > Methane
    Chemical compounds > Oxygen compounds > Oxides > Nitrogen compounds > Nitrous oxide
    Layers > Water column
    Pollution > Air pollution
    Topographic features > Landforms > Coastal landforms > Tidal flats
    Water bodies > Coastal waters > Coastal landforms > Coastal inlets > Estuaries
    Schelde [Marine Regions]; Thames Estuary [Marine Regions]
Authors  Top 
  • Middelburg, J.J.
  • de Bie, M.J.M.
  • Nieuwenhuize, J.
Abstract
    Estuaries contribute significantly (5-10 %) to the marine emission budget of methane and nitrous oxide. During the BIOGEST project we have measured the distribution of these two gases in the water column of nine tidal estuaries. In well-mixed estuaries, methane concentrations were high in the river end-member and initially decreased with increasing salinity, then increased at intermediate or high salinities before decreasing again going offshore. Tidal flats and creeks were identified as a methane sources to estuarine waters. Methane concentrations in river-dominated stratified estuaries were rather erratic. Nitrous oxide concentrations were always above atmospheric saturation levels and showed consistent and systematic relationships with distribution patterns of oxygen, ammonium, nitrite and nitrification activities. Nitrous oxide concentrations were very high in ammonium-rich and oxygen-depleted systems such as the Scheldt and Thames estuaries. Nitrous oxide concentrations were also high in the suboxic zone of fluidised mud systems of the Gironde estuary. If time permits, we will show laboratory results for nitrous oxide production in Scheldt water and we will speculate on the role of sediment versus water-column processes.
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