Ocean acidification state in western Antarctic surface waters: controls and interannual variability
During four austral summers (December to January) from 2006 to 2010, we investigated the surface-water carbonate system and its controls in the western Antarctic Ocean. Measurements of total alkalinity ( A T ), pH and total inorganic carbon ( C T ) were investigated in combination with high-frequenc...
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ftcopernicus:oai:publications.copernicus.org:bg19753 2023-05-15T13:24:18+02:00 Ocean acidification state in western Antarctic surface waters: controls and interannual variability Mattsdotter Björk, M. Fransson, A. Torstensson, A. Chierici, M. 2018-09-27 application/pdf https://doi.org/10.5194/bg-11-57-2014 https://www.biogeosciences.net/11/57/2014/ eng eng doi:10.5194/bg-11-57-2014 https://www.biogeosciences.net/11/57/2014/ eISSN: 1726-4189 Text 2018 ftcopernicus https://doi.org/10.5194/bg-11-57-2014 2019-12-24T09:54:46Z During four austral summers (December to January) from 2006 to 2010, we investigated the surface-water carbonate system and its controls in the western Antarctic Ocean. Measurements of total alkalinity ( A T ), pH and total inorganic carbon ( C T ) were investigated in combination with high-frequency measurements on sea-surface temperature (SST), salinity and Chl a . In all parameters we found large interannual variability due to differences in sea-ice concentration, physical processes and primary production. The main result from our observations suggests that primary production was the major control on the calcium carbonate saturation state (Ω) in austral summer for all years. This was mainly reflected in the covariance of pH and Chl a . In the sea-ice-covered parts of the study area, pH and Ω were generally low, coinciding with low Chl a concentrations. The lowest pH in situ and lowest aragonite saturation (Ω Ar ~ 1.0) were observed in December 2007 in the coastal Amundsen and Ross seas near marine outflowing glaciers. These low Ω and high pH values were likely influenced by freshwater dilution. Comparing 2007 and 2010, the largest Ω Ar difference was found in the eastern Ross Sea, where Ω Ar was about 1.2 units lower in 2007 than in 2010. This was mainly explained by differences in Chl a (i.e primary production). In 2010 the surface water along the Ross Sea shelf was the warmest and most saline, indicating upwelling of nutrient and CO 2 -rich sub-surface water, likely promoting primary production leading to high Ω and pH. Results from multivariate analysis agree with our observations showing that changes in Chl a had the largest influence on the Ω Ar variability. The future changes of Ω Ar were estimated using reported rates of the oceanic uptake of anthropogenic CO 2 , combined with our data on total alkalinity, SST and salinity (summer situation). Our study suggests that the Amundsen Sea will become undersaturated with regard to aragonite about 40 yr sooner than predicted by models. Text Amundsen Sea Antarc* Antarctic Antarctic Ocean Ocean acidification Ross Sea Sea ice Copernicus Publications: E-Journals Amundsen Sea Antarctic Antarctic Ocean Austral Ross Sea Biogeosciences 11 1 57 73 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
During four austral summers (December to January) from 2006 to 2010, we investigated the surface-water carbonate system and its controls in the western Antarctic Ocean. Measurements of total alkalinity ( A T ), pH and total inorganic carbon ( C T ) were investigated in combination with high-frequency measurements on sea-surface temperature (SST), salinity and Chl a . In all parameters we found large interannual variability due to differences in sea-ice concentration, physical processes and primary production. The main result from our observations suggests that primary production was the major control on the calcium carbonate saturation state (Ω) in austral summer for all years. This was mainly reflected in the covariance of pH and Chl a . In the sea-ice-covered parts of the study area, pH and Ω were generally low, coinciding with low Chl a concentrations. The lowest pH in situ and lowest aragonite saturation (Ω Ar ~ 1.0) were observed in December 2007 in the coastal Amundsen and Ross seas near marine outflowing glaciers. These low Ω and high pH values were likely influenced by freshwater dilution. Comparing 2007 and 2010, the largest Ω Ar difference was found in the eastern Ross Sea, where Ω Ar was about 1.2 units lower in 2007 than in 2010. This was mainly explained by differences in Chl a (i.e primary production). In 2010 the surface water along the Ross Sea shelf was the warmest and most saline, indicating upwelling of nutrient and CO 2 -rich sub-surface water, likely promoting primary production leading to high Ω and pH. Results from multivariate analysis agree with our observations showing that changes in Chl a had the largest influence on the Ω Ar variability. The future changes of Ω Ar were estimated using reported rates of the oceanic uptake of anthropogenic CO 2 , combined with our data on total alkalinity, SST and salinity (summer situation). Our study suggests that the Amundsen Sea will become undersaturated with regard to aragonite about 40 yr sooner than predicted by models. |
format |
Text |
author |
Mattsdotter Björk, M. Fransson, A. Torstensson, A. Chierici, M. |
spellingShingle |
Mattsdotter Björk, M. Fransson, A. Torstensson, A. Chierici, M. Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
author_facet |
Mattsdotter Björk, M. Fransson, A. Torstensson, A. Chierici, M. |
author_sort |
Mattsdotter Björk, M. |
title |
Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
title_short |
Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
title_full |
Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
title_fullStr |
Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
title_full_unstemmed |
Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
title_sort |
ocean acidification state in western antarctic surface waters: controls and interannual variability |
publishDate |
2018 |
url |
https://doi.org/10.5194/bg-11-57-2014 https://www.biogeosciences.net/11/57/2014/ |
geographic |
Amundsen Sea Antarctic Antarctic Ocean Austral Ross Sea |
geographic_facet |
Amundsen Sea Antarctic Antarctic Ocean Austral Ross Sea |
genre |
Amundsen Sea Antarc* Antarctic Antarctic Ocean Ocean acidification Ross Sea Sea ice |
genre_facet |
Amundsen Sea Antarc* Antarctic Antarctic Ocean Ocean acidification Ross Sea Sea ice |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-11-57-2014 https://www.biogeosciences.net/11/57/2014/ |
op_doi |
https://doi.org/10.5194/bg-11-57-2014 |
container_title |
Biogeosciences |
container_volume |
11 |
container_issue |
1 |
container_start_page |
57 |
op_container_end_page |
73 |
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1766378603959812096 |