Anthropogenic CO2 and ocean acidification in Argentine Basin Water Masses over almost five decades of observations

• Published in: Science of The Total Environment
• Main Authors: Fontela, Marcos, Velo, A., Gilcoto, Miguel, Pérez, Fiz F.
• Other Authors: European Commission
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: Ocean acidification; Anthropogenic carbon; Carbonate; Deoxygenation; Argentine basin; Western South Atlantic; Antarctic; Argentine; Antarc*; South Atlantic Ocean
• Online Access: http://hdl.handle.net/10261/236658; https://doi.org/10.1016/j.scitotenv.2021.146570; https://doi.org/10.13039/501100000780

9 pages, 5 figures, 2 tables.-- Under a Creative Commons license The chemical conditions of the Argentine Basin (western South Atlantic Ocean) water masses are evaluated with measurements from eleven hydrographic cruises to detect and quantify anthropogenic and natural stressors in the ocean carbon system. The database covers almost half-century (1972–2019), a time-span where the mean annual atmospheric carbon dioxide concentration (CO2atm) increased from 325 to 408 ppm of volume (ppm). This increase of atmospheric CO2 (83 ppm, the 64% of the total anthropogenic signal in the atmosphere) leads to an increase in anthropogenic carbon (Cant) across all the water column and the consequent ocean acidification: a decrease in excess carbonate that is unequivocal in the upper (South Atlantic Central Water, SACW) and intermediate water masses (Sub Antarctic Mode Water, SAMW and Antarctic Intermediate Water, AAIW). For each additional ppm in CO2atm the water masses SACW, SAMW and AAIW lose excess carbonate at a rate of 0.39 ± 0.04, 0.47 ± 0.05 and 0.23 ± 0.03 μmol·kg−1·ppm−1 respectively. Modal and intermediate water masses in the Argentine Basin are very sensitive to carbon increases due low buffering capacity. The large rate of AAIW acidification is the synergic effect of carbon uptake combined with deoxygenation and increased remineralization of organic matter. If CO2 emissions follows the path of business-as-usual emissions (SSP 5.85), SACW would become undersaturated with respect to aragonite at the end of the century. The undersaturation in AAIW is virtually unavoidable For this work M. Fontela was funded by Portuguese national funds from FCT - Foundation for Science and Technology through project UIDB/Multi/04326/2020 and CEECINST/00114/2018. A. Velo and F. F. Pérez were supported by the BOCATS2 Project (PID2019-104279GB-C21) co-funded by the Spanish Government and the Fondo Europeo de Desarrollo Regional (FEDER). A. Velo, M.Gilcoto and F. F. Pérez were supported by the European Union‘s Horizon 2020 research ...