Aquatic Geochemistry

, Volume 19, Issue 5–6, pp 399–442

Carbonate Chemistry and Air–Sea CO2 Flux in a NW Mediterranean Bay Over a Four-Year Period: 2007–2011

  • Eric Heinen De Carlo
  • Laure Mousseau
  • Ornella Passafiume
  • Patrick S. Drupp
  • Jean-Pierre Gattuso
Original Paper

DOI: 10.1007/s10498-013-9217-4

Cite this article as:
De Carlo, E.H., Mousseau, L., Passafiume, O. et al. Aquat Geochem (2013) 19: 399. doi:10.1007/s10498-013-9217-4

Abstract

The Service d’Observation de la Rade de Villefranche-sur-Mer is designed to study the temporal variability of hydrological conditions as well as the abundance and composition of holo- and meroplankton at a fixed station in this bay of the northwest Mediterranean. The weekly data collected at this site, designated as “Point B” since 1957, represent a long-term time series of hydrological conditions in a coastal environment. Since 2007, the historical measurements of hydrological and biological conditions have been complemented by measurements of the CO2–carbonic acid system parameters. In this contribution, CO2–carbonic acid system parameters and ancillary data are presented for the period 2007–2011. The data are evaluated in the context of the physical and biogeochemical processes that contribute to variations in CO2 in the water column and exchange of this gas between the ocean and atmosphere. Seasonal cycles of the partial pressure of CO2 in seawater (pCO2) are controlled principally by variations in temperature, showing maxima in the summer and minima during the winter. Normalization of pCO2 to the mean seawater temperature (18.5 °C), however, reveals an apparent reversal of the seasonal cycle with maxima observed in the winter and minima in the summer, consistent with a biogeochemical control of pCO2 by primary production. Calculations of fluxes of CO2 show this area to be a weak source of CO2 to the atmosphere during the summer and a weak sink during the winter but near neutral overall (range −0.3 to +0.3 mmol CO2 m−2 h−1, average 0.02 mmol CO2 m−2 h−1). We also provide an assessment of errors incurred from the estimation of annual fluxes of CO2 as a function of sampling frequency (3-hourly, daily, weekly), using data obtained at the Hawaii Kilo Nalu coastal time-series station, which shows similar behavior to the Point B location despite significant differences in climate and hydrological conditions and the proximity of a coral reef ecosystem.

Keywords

CO2 Carbonic acid Coastal Mediterranean Gas exchange Primary productivity 

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Eric Heinen De Carlo
    • 1
  • Laure Mousseau
    • 2
    • 3
  • Ornella Passafiume
    • 2
    • 3
  • Patrick S. Drupp
    • 1
  • Jean-Pierre Gattuso
    • 2
    • 3
  1. 1.Department of OceanographyUniversity of Hawaii at ManoaHonoluluUSA
  2. 2.Laboratoire d’Océanographie de Villefranche-sur-MerCNRS-INSUVillefranche-sur-Mer CedexFrance
  3. 3.Observatoire Océanologique de VillefrancheUniversité Pierre et Marie Curie-Paris 6Villefranche-sur-MerFrance

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