Biogeochemistry

, Volume 59, Issue 1, pp 95–119

Methane distribution in European tidal estuaries

  • Jack J. Middelburg
  • Joop Nieuwenhuize
  • Niels Iversen
  • Nana Høgh
  • Hein de Wilde
  • Wim Helder
  • Richard Seifert
  • Oliver Christof
Article

DOI: 10.1023/A:1015515130419

Cite this article as:
Middelburg, J.J., Nieuwenhuize, J., Iversen, N. et al. Biogeochemistry (2002) 59: 95. doi:10.1023/A:1015515130419

Abstract

Methane concentrations have been measured along salinity profilesin nine tidal estuaries in Europe (Elbe, Ems, Thames, Rhine,Scheldt, Loire, Gironde, Douro and Sado). The Rhine, Scheldt andGironde estuaries have been studied seasonally. A number ofdifferent methodologies have been used and they yieldedconsistent results. Surface water concentrations ranged from0.002 to 3.6 μM, corresponding to saturation ratios of 0.7 to1580 with a median of 25. Methane concentrations in thefresh-water end-members varied from 0.01 to 1.4 μM. Methaneconcentrations in the marine end-members were close to saturationoffshore and on the order of 0.1 μM in estuarine plumes. Methaneversus salinity profiles in river-dominated, stratified estuaries(Rhine and Douro) appeared rather erratic whereas those in thewell mixed, long-residence time estuaries (Elbe, Ems, Thames,Scheldt, Loire, Gironde and Sado) revealed consistent trends. Inthese systems dissolved methane initially decreases withincreasing salinity, then increases to a maximum at intermediateto high salinities before decreasing again going offshore. Tidalflats and creeks were identified as a methane source to estuarinewaters. The global estuarine flux of methane to the atmospherehas been calculated by combining the median water-air methanegradient (68.2 nmol dm−3) with a global area weighted transfercoefficient and the global area of estuaries. Estuaries emit 1.1to 3.0 Tg CH4 yr−1, which is less than 9% of the global marinemethane emission.

DouroElbeemissionEmsestuariesGirondeLoiremethaneRhineriversSadoScheldtThames

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Jack J. Middelburg
    • 1
  • Joop Nieuwenhuize
    • 1
  • Niels Iversen
    • 2
  • Nana Høgh
    • 2
  • Hein de Wilde
    • 3
  • Wim Helder
    • 3
  • Richard Seifert
    • 4
  • Oliver Christof
    • 4
  1. 1.Netherlands Institute of EcologyNT YersekeThe Netherlands
  2. 2.Department of Civil Engineering, Environmental Engineering LaboratoryAalborg UniversityAalborgDenmark
  3. 3.Netherlands Institute of Sea ResearchDen BurgThe Netherlands
  4. 4.Institute of Biogeochemistry and Marine ChemistryUniversity of HamburgHamburgGermany
  5. 5.ECNPettenThe Netherlands