Hydrobiologia

, Volume 588, Issue 1, pp 245–259

Particulate organic carbon in the estuarine turbidity maxima of the Gironde, Loire and Seine estuaries: origin and lability

  • Henri Etcheber
  • Aurélien Taillez
  • Gwenaël Abril
  • Josette Garnier
  • Pierre Servais
  • Florentina Moatar
  • Marc-Vincent Commarieu
ECSA38

Abstract

A study of the particulate organic carbon (POC) in the estuarine turbidity maxima (ETMs) of the three major French macrotidal estuaries shows that the average contents are 1.5, 3.3 and 3.1% (expressed in % of dry suspended sediment) in the Gironde, Loire and Seine Estuaries, respectively. There is no seasonal variation of POC contents in the Gironde Estuary, whereas, they often increase in the Loire and the Seine Estuaries in spring and summer. The lability of the estuarine particulate organic matter was estimated by two analyses: 1/labile organic matter was measured as the organic carbon loss during incubation tests over one month; 2/ the hydrolysable organic fraction was determined after 6N HCl digestion. The organic fractions of the ETMs are mainly refractory. Any increase in the amount of POC as compared to the background levels (cited above) is always correlated to an increase of organic matter lability. The yearly average fluvial contributions by various particulate organic pools (soil and litter organic matter; organic matter of phytoplanktonic and human origin) that enter the three estuaries were quantified. In the Garonne River, soil and litter are the major (90%) POC sources. In the Loire system, due to the eutrophication of the river water, phytoplankton contributes up to 50% of the total POC load. In the Seine river, soil and litter contribute 70% of the total POC input; POC of human origin is also significant (10%), due to the impact of the City of Paris (10 million inhabitants). The lability of the different types of organic matter ranks as follows: phytoplankton ∼litter > human-origin organic matter >> soil. By combining the POC budgets and the lability of each type of organic fraction, it was possible to explain why the POC of the three ETMs is different and characterizes its refractory vs. labile nature.

Keywords

Estuaries Particulate organic matter Source Lability 

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Henri Etcheber
    • 1
  • Aurélien Taillez
    • 1
  • Gwenaël Abril
    • 1
  • Josette Garnier
    • 2
  • Pierre Servais
    • 3
  • Florentina Moatar
    • 4
  • Marc-Vincent Commarieu
    • 1
  1. 1.Département de Géologie et OcéanographieUMR CNRS 5805 EPOC, Université Bordeaux 1Talence CedexFrance
  2. 2.Laboratoire Sisyphe, UMR 7619, Boite 123Université Pierre et Marie Curie Paris VIParis Cedex 05France
  3. 3.Ecologie des Systèmes AquatiquesUniversité Libre de BruxellesBruxellesBelgium
  4. 4.Laboratoire de Géologie des Environnements Aquatiques ContinentauxUniversité de ToursToursFrance

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