Rapid acidification of mode and intermediate waters in the southwestern Atlantic Ocean

• Published in: Biogeosciences
• Main Authors: Salt, Lesley A., Heuven, S. M. A. C., Van, Claus, M. E., Jones, E. M., Baar, H. J. W., De
• Other Authors: CHImie Marine (CHIM), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre for Isotope Research Groningen (CIO), University of Groningen Groningen, Department of Ocean Ecosystems, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI), Helmholtz-Gemeinschaft = Helmholtz Association, Royal Netherlands Institute for Sea Research (NIOZ), Earth and Life Sciences division (ALW) of the Netherlands Organisation for Scientific Research (NWO) 817.01.004, EU - European Commission 264879
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDV]Life Sciences [q-bio]; [SDE]Environmental Sciences; Antarctic; Antarc*
• Online Access: https://hal.science/hal-01251672; https://hal.science/hal-01251672/document; https://hal.science/hal-01251672/file/bg-12-1387-2015.pdf; https://doi.org/10.5194/bg-12-1387-2015

International audience Observations along the southwestern Atlantic WOCE A17 line made during the Dutch GEOTRACESNL programme (2010-2011) were compared with historical data from 1994 to quantify the changes in the anthropogenic component of the total pool of dissolved inorganic carbon (Delta C-ant). Application of the extended multilinear regression (eMLR) method shows that the Delta C-ant from 1994 to 2011 has largely remained confined to the upper 1000 dbar. The greatest changes occur in the upper 200 dbar in the Subantarctic Zone (SAZ), where a maximum increase of 37 mu mol kg(-1) is found. South Atlantic Central Water (SACW) experienced the highest rate of increase in C-ant, at 0.99 +/- 0.14 mu mol kg(-1) yr(-1), resulting in a maximum rate of decrease in pH of 0.0016 yr(-1). The highest rates of acidification relative to Delta C-ant, however, were found in Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW). The low buffering capacity of SAMW and AAIW combined with their relatively high rates of C-ant increase of 0.53 +/- 0.11 and 0.36 +/- 0.06 mu mol kg(-1) yr(-1), respectively, has lead to rapid acidification in the SAZ, and will continue to do so whilst simultaneously reducing the chemical buffering capacity of this significant CO2 sink.