Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 15, issue 16
Biogeosciences, 15, 5221-5236, 2018
https://doi.org/10.5194/bg-15-5221-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue: Interactions between planktonic organisms and biogeochemical...

Biogeosciences, 15, 5221-5236, 2018
https://doi.org/10.5194/bg-15-5221-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 29 Aug 2018

Research article | 29 Aug 2018

Carbonate system distribution, anthropogenic carbon and acidification in the western tropical South Pacific (OUTPACE 2015 transect)

Thibaut Wagener1, Nicolas Metzl2, Mathieu Caffin1, Jonathan Fin2, Sandra Helias Nunige1, Dominique Lefevre1, Claire Lo Monaco2, Gilles Rougier1, and Thierry Moutin1 Thibaut Wagener et al.
  • 1Aix Marseille Univ, CNRS, IRD, Université de Toulon, MIO UM 110, 13288, Marseille, France
  • 2Sorbonne Université, CNRS, IRD, MNHN, Laboratoire d'océanographie et du climat: expérimentation et approches numériques (LOCEAN), Case 100, 4 place Jussieu, 75252 Paris CEDEX 05, France

Abstract. The western tropical South Pacific was sampled along a longitudinal 4000km transect (OUTPACE cruise, 18 February, 3 April 2015) for the measurement of carbonate parameters (total alkalinity and total inorganic carbon) between the Melanesian Archipelago (MA) and the western part of the South Pacific gyre (WGY). This paper reports this new dataset and derived properties: pH on the total scale (pHT) and the CaCO3 saturation state with respect to aragonite (Ωara). We also estimate anthropogenic carbon (CANT) distribution in the water column using the TrOCA method (Tracer combining Oxygen, inorganic Carbon and total Alkalinity). Along the OUTPACE transect a deeper penetration of CANT in the intermediate waters was observed in the MA, whereas highest CANT concentrations were detected in the subsurface waters of the WGY. By combining our OUTPACE dataset with data available in GLODAPv2 (1974–2009), temporal changes in oceanic inorganic carbon were evaluated. An increase of 1.3 to 1.6µmolkg−1a−1 for total inorganic carbon in the upper thermocline waters is estimated, whereas CANT increases by 1.1 to 1.2µmolkg−1a−1. In the MA intermediate waters (27kgm−3 < σθ < 27.2kgm−3) an increase of 0.4µmolkg−1a−1 CANT is detected. Our results suggest a clear progression of ocean acidification in the western tropical South Pacific with a decrease in the oceanic pHT of up to −0.0027a−1 and a shoaling of the saturation depth for aragonite of up to 200m since the pre-industrial period.

Please read the corrigendum first before accessing the article.
Publications Copernicus
Special issue
Download
Notice on corrigendum

The requested paper has a corresponding corrigendum published. Please read the corrigendum first before downloading the article.

Short summary
The western tropical South Pacific was sampled along a longitudinal 4000 km transect (OUTPACE cruise) for the measurement of carbonate parameters (total alkalinity and total inorganic carbon) between the Melanesian Archipelago and the western part of the South Pacific gyre. This paper reports this new dataset and derived properties. We also estimate anthropogenic carbon distribution in the water column using the TrOCA method.
The western tropical South Pacific was sampled along a longitudinal 4000 km transect (OUTPACE...
Citation
Share