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

摘要

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 (C-ANT) 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 (C-T) data showed a C-T increase of 30.0 +/- 1.0 mu mol kg(-1) per decade. This decadal increase is mainly due to the C-ANT penetration (43.2 mu mol kg(-1) per decade) in surface waters, which is mitigated for by relatively small opposing changes in C-T due to physical and biological processes. (C) 2016 Elsevier Ltd. All rights reserved.