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Biogeochemistry

, Volume 59, Issue 1–2, pp 207–237 | Cite as

Application of a transport-reaction model to the estimation of biogas fluxes in the Scheldt estuary

  • J.P. Vanderborght
  • R. Wollast
  • M. Loijens
  • P. Regnier
Article

Abstract

In the frame of the BIOGEST project, the fulltransient, one-dimensional, reactive-transportmodel CONTRASTE has been extended for thecomputation of biogases in the Scheldt estuary. The CONTRASTE model (Coupled, Networked, Transport-Reaction Algorithm for Strong T> idal Estuaries) provides a satisfactorydescription of the estuarine residualcirculation (including daily freshwaterdischarge and a complete description of thetide) and a flexible implementation of thevarious physico-chemical and biologicaltransformations, including bothkinetically-controlled and equilibriumreactions. The model allows resolution of thecomplex, nonlinear collective behaviour of thistype of system and investigation of thenon-steady-state phenomena which governestuarine dynamics. Variables currentlyimplemented in the model include salinity,suspended matter, oxygen, inorganic carbonspecies, degradable organic carbon andnitrogen, inorganic nitrogen species,freshwater and marine phytoplankton. Biologicalprocesses described are heterotrophicrespiration, primary production, nitrificationand denitrification. Equilibrium formulationsallow for DIC and NH4+/NH3speciation. Physical processes include gastransfer at the water/air interface, dependingon both wind speed and current velocity. pHprofiles are explicitly computed and constitutea very sensitive check of the overall modelconsistency. Results of the CONTRASTE model arein very good agreement with the measuredlongitudinal distribution of the variablesconsidered, in particular O2, pH,pCO2 and N2O concentrations. However,discrepancies are observed between thecalculated fluxes of CO2 and thoseestimated using an in situ floatingchamber. It is shown that the evaluation of gastransfer can be affected by serious errors ifthe variations due to changes in currentvelocity and water depth during one tidal cycleare not taken into consideration. The modelalso shows that the fluxes of biogases inestuaries are greatly influenced by thequasi-exponential increase of the exchangesurface area with decreasing distance to thesea. Our estimation of the total daily flux ofO2, CO2 and N2O is equal to+28500, −19000 and −17 kmoles.day−1respectively for the Scheldt estuary in July 1996.

biogas fluxes CO2 estuary N2Scheldt transport-reaction model 

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References

  1. Benson BB & Krause D (1984) The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnol. Oceanogr. 23: 620–632Google Scholar
  2. Billen G, Lancelot C, De Becker E. & Servais P (1988) Modelling microbial processes (phytoand bacterioplankton) in the Scheldt estuary. Hydrobiol. Bull. 22: 43–55Google Scholar
  3. Brion N & Billen G (1998) A re-assessment of H14CO3 incorporation method for measuring autotrophic nitrification and its use to estimate nitrifying biomasses. Revue des Sciences de l'Eau 11: 283–302Google Scholar
  4. Cai W & Wang Y (1998) The chemistry, fluxes, and sources of carbon dioxide in the estuarine waters of the Satilla and Altamaha Rivers, Georgia. Limnol. Oceanog. 43: 657–668Google Scholar
  5. Clegg S & Whitfield M (1995) A chemical model of seawater including dissolved ammonia and stoichiometric dissociation constant of ammonia in estuarine water and seawater from-2 to 40 °C. Geochim. Cosmochim. Acta 59: 2403–2421Google Scholar
  6. De Wilde HPJ & de Bie MJM (2000) Nitrous oxide in the Schelde estuary: production by nitrification and emission to the atmosphere. Mar. Chem. 69: 203–216Google Scholar
  7. Dronkers J (1964) Tidal Composition in Rivers and Coastal Waters. North-Holland, New-YorkGoogle Scholar
  8. Edmund JM & Gieskes JM (1970) On the calculation of degree of saturation of seawater with respect to calcium carbonate under in situ conditions. Geochim. Cosmochim. Acta 34: 1261–1291Google Scholar
  9. Frankignoulle M (1988) Field measurements of air-sea CO2 exchange. Limnol. Oceanogr. 33: 313–322Google Scholar
  10. Frankignoulle M, Bourge I & Wollast R (1996) Atmospheric CO2 fluxes in a highly polluted esturay (the Scheldt). Limnol. Oceanoghr. 41: 365–369Google Scholar
  11. Frankignoulle M, Abril G, Borges A, Bourge I, Canon C, Delille B, Libert E & Theate JM (1998) Carbon dioxide emission from European estuaries. Science, 282: 434–436Google Scholar
  12. IRM (1996) Bulletin mensuel de l'Institut Royal Météorologique de Belgique. Observations climatologiques, Partie I et II, Juin-Juillet 1996. In:Malcorps H (Ed) Bruxelles. 39 + 36 ppGoogle Scholar
  13. Mehrbach C, Cuberson CH, Hawley JE & Pytkowicz RM (1973) Measurement of the apparent dissociation constants of carbonic acid in seawater at atmospheric pressure. Limnol. Oceanogr. 18: 897–907Google Scholar
  14. Mook WG & Koene BKS (1975) Chemistry of dissolved inorganic carbon in estuarine and coastal brackish waters. Estuar. Coastal Mar. Sci. 3: 325–336Google Scholar
  15. O'Connor DJ & Dobbins WE (1956) Mechanism of reaeration in natural streams. J. Sanitary Eng. Div. ASCE 82(SA6): 1–30Google Scholar
  16. Platt T, Gallegos CL & Harisson WG (1980) Photoinhibition of photosynthesis in natural assemblages in marine phytoplankton. J. Mar. Res. 38: 687–701Google Scholar
  17. Platt T, Satthyendranath S & Ravindran P (1990) Primary production by phytoplankton: analytic solutions for daily rates per unit area of water surface. Proc. R. Soc. Lond. 241: 101–111Google Scholar
  18. Regnier P, Wollast R & Steefel CI (1997) Long term fluxes of reactive species in macrotidal estuaries: Estimates from a fully transient, multi-component reaction transport model. Mar. Chem. 58: 127–145Google Scholar
  19. Regnier P, Mouchet A, Wollast R & Ronday F (1998) A discussion of methods for estimating residual fluxes in strong tidal estuaries. Cont. Shelf Res. 18: 1543–1571Google Scholar
  20. Regnier P & Steefel CI (1999) A high resolution estimate of the inorganic nitrogen flux from the Scheldt estuary to the coastal North Sea during a nitrogen-limited algal bloom, Spring 1995. Geochim. Cosmochim. Acta 63: 1359–1374Google Scholar
  21. Sander R (1999) Compilation of Henry's law constants for inorganic and organic species of potential importance in environmental chemistry. http://www.mpch-mainz.mpg.de/~sanders/res /henry.htmlGoogle Scholar
  22. SAWES (1991) Waterkwaliteitsmodel Westerschelde. WL-rapport T527.Google Scholar
  23. Soetaert K & Herman PMJ (1993) MOSES-model of the Scheldt estuary: Ecosystem model development under SENECA. Report NIOO. Yerseke, The NetherlandsGoogle Scholar
  24. Somville M (1984) Use of nitrifying activity measurements for describing the effect of salinity on nitrification in the Scheldt estuary. Appl. Environ. Microbiol. 47: 424–426Google Scholar
  25. Van Damme S, Meire P, Maeckelberghe H, Verdievel M, Bourgoing L, Taveniers E, Ysebaert T & Wattel G (1995) De waterkwaliteit van de zeeschelde: evolutie in de voorbije dertig jaar. Water 85: 244–256. In Dutch with a summary in EnglishGoogle Scholar
  26. Wanninkhof R (1992) Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res. 97: 7373–7382Google Scholar
  27. Weiss RF & Price BA (1980). Nitrous oxide solubility in water and seawater. Mar. Chem. 8: 347–359Google Scholar
  28. Wollast R (1988) The Scheldt estuary. In: Salomon W, Bayne B, Duursma EK & Forstner U (Eds) Pollution of the North-Sea: An Assessment (pp 183–193). Springer VerlagGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • J.P. Vanderborght
    • 1
  • R. Wollast
    • 1
  • M. Loijens
    • 1
  • P. Regnier
    • 2
  1. 1.Université Libre de Bruxelles Laboratory of Chemical Oceanography Bd du TriompheBrusselsBelgium
  2. 2.Utrecht University Department of GeochemistryTA UtrechtThe Netherlands

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