Rapid acidification of mode and intermediate waters in the southwestern Atlantic Ocean
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)....
Published in: | Biogeosciences |
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Main Authors: | , , , , |
Other Authors: | , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2015
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Subjects: | |
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 |
Summary: | 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. |
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