Anthropogenic CO2 changes in the Equatorial Atlantic Ocean

Methods based on CO2 and chlorofluorocarbon (CFC) data are used to describe and evaluate the anthropogenic CO2 (C-ant) concentrations, C-ant specific inventories, and C-ant storage rates in the Equatorial Atlantic Ocean. The C-ant variability in the water masses is evaluated from the comparison of two hydrographic sections along 7.5 degrees N carried out in 1993 and 2010. During both cruises, high C-ant concentrations are detected in the upper layers, with values decreasing progressively towards the deep layers. Overall, the C-ant concentrations increase from 1993 to 2010, with a large increment in the upper North Atlantic Deep Water layer of about 0.18 +/- 0.03 mu mol kg(-1) y(-1). In 2010, the C-ant inventory along the whole section amounts to 58.9 +/- 2.2 and 45.1 +/- 2.0 mol m(-2) using CO2 and CFC based methods, respectively, with most C-ant accumulating in the western basin. Considering the time elapsed between the two cruises, C-ant storage rates of 1.01 +/- 0.18 and 0.75 +/- 0.17 mol m(-2) y(-1) (CO2 and CFC based methods, respectively) are obtained. Below similar to 1000 m, these rates follow the pace expected from a progressive increase of C-ant at steady state; above similar to 1000 m, C-ant increases faster, mainly due to the retreat of the Antarctic Intermediate Waters. (C) 2015 Elsevier Ltd. All rights reserved.