Time variability of the north-western Mediterranean Sea pH over 1995–2011

Koffi Marcellin Yao (1) , Olivier Marcou (2) , Catherine Goyet (2) , Véronique Guglielmi (2) , Franck Touratier (2) , Jean-Philippe Savy (2)

1 CRO - Centre de Recherches Océanologiques [Abidjan]
2 IMAGES-Espace DEV - Institut de Modélisation et d'Analyses en géo-environnement et santé - Espace Développement

Factors controlling ocean acidification and its temporal variations were studied over the 1995–2011 period at the Dyfamed site at 10 m depth, in the North Mediterranean Sea. The results indicated a mean annual decrease of 0.003 ± 0.001 pH units on the seawater scale. The seasonal variability was characterized by a pH decrease during springtime and a strong pH increase in late fall. Anthropogenic CO2 (CANT) absorption by the ocean was the key driver of seawater acidification in this region, accounting for about 70% of the observed drop in pH, followed by water temperature (about 30%). The total inorganic carbon (CT) data showed a CT increase of 30.0 ± 1.0 μmol kg−1 per decade. This decadal increase is mainly due to the CANT penetration (43.2 μmol kg−1 per decade) in surface waters, which is mitigated for by relatively small opposing changes in CT due to physical and biological processes.

Mots clés: Ocean acidification; Anthropogenic CO2; Mediterranean sea

Domaines: Océanographie

Koffi Marcellin Yao, Olivier Marcou, Catherine Goyet, Véronique Guglielmi, Franck Touratier, et al.. Time variability of the north-western Mediterranean Sea pH over 1995–2011. Marine Environmental Research, 2016, ⟨10.1016/j.marenvres.2016.02.016⟩. ⟨hal-01286093⟩