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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ftdoajarticles:oai:doaj.org/article:66ee964883a74b61b1f2cbc049edab7c 2023-05-15T13:24:18+02:00 Ocean acidification state in western Antarctic surface waters: controls and interannual variability M. Mattsdotter Björk A. Fransson A. Torstensson M. Chierici 2014-01-01T00:00:00Z https://doi.org/10.5194/bg-11-57-2014 https://doaj.org/article/66ee964883a74b61b1f2cbc049edab7c EN eng Copernicus Publications http://www.biogeosciences.net/11/57/2014/bg-11-57-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-57-2014 https://doaj.org/article/66ee964883a74b61b1f2cbc049edab7c Biogeosciences, Vol 11, Iss 1, Pp 57-73 (2014) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/bg-11-57-2014 2022-12-31T00:02:04Z 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. Article in Journal/Newspaper Amundsen Sea Antarc* Antarctic Antarctic Ocean Ocean acidification Ross Sea Sea ice Directory of Open Access Journals: DOAJ Articles Antarctic Austral Ross Sea Amundsen Sea Antarctic Ocean Biogeosciences 11 1 57 73 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 M. Mattsdotter Björk A. Fransson A. Torstensson M. Chierici Ocean acidification state in western Antarctic surface waters: controls and interannual variability |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
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 |
Article in Journal/Newspaper |
author |
M. Mattsdotter Björk A. Fransson A. Torstensson M. Chierici |
author_facet |
M. Mattsdotter Björk A. Fransson A. Torstensson M. Chierici |
author_sort |
M. Mattsdotter Björk |
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 |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/bg-11-57-2014 https://doaj.org/article/66ee964883a74b61b1f2cbc049edab7c |
geographic |
Antarctic Austral Ross Sea Amundsen Sea Antarctic Ocean |
geographic_facet |
Antarctic Austral Ross Sea Amundsen Sea Antarctic Ocean |
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 |
Biogeosciences, Vol 11, Iss 1, Pp 57-73 (2014) |
op_relation |
http://www.biogeosciences.net/11/57/2014/bg-11-57-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-57-2014 https://doaj.org/article/66ee964883a74b61b1f2cbc049edab7c |
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 |
_version_ |
1766378667498274816 |