Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2
The carbon isotopic composition of organic matter ( 13Corg) was measured for particles suspended in surface waters (from six north-south transects across the subantarctic (SAZ) and polar frontal zones (PFZ) of the Southern Ocean south of Australia between September 1997 and March 1998), and obtained...
Published in: | Deep Sea Research Part I: Oceanographic Research Papers |
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Online Access: | https://doi.org/10.1016/j.dsr.2003.10.002 http://ecite.utas.edu.au/32062 |
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ftunivtasecite:oai:ecite.utas.edu.au:32062 2023-05-15T18:19:01+02:00 Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 Lourey, MJ Trull, T Tilbrook, B 2004 https://doi.org/10.1016/j.dsr.2003.10.002 http://ecite.utas.edu.au/32062 en eng Elsevier Ltd http://dx.doi.org/10.1016/j.dsr.2003.10.002 Lourey, MJ and Trull, T and Tilbrook, B, Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 , Deep-Sea Research Part 1, 51, (2) pp. 281-305. ISSN 0967-0637 (2004) [Refereed Article] http://ecite.utas.edu.au/32062 Earth Sciences Oceanography Chemical Oceanography Refereed Article PeerReviewed 2004 ftunivtasecite https://doi.org/10.1016/j.dsr.2003.10.002 2019-12-13T21:11:31Z The carbon isotopic composition of organic matter ( 13Corg) was measured for particles suspended in surface waters (from six north-south transects across the subantarctic (SAZ) and polar frontal zones (PFZ) of the Southern Ocean south of Australia between September 1997 and March 1998), and obtained from sediment traps deployed during the same period at 1060, 2050 and 3850m depth in the SAZ (47S), 3080m under the Subantarctic Front (51S) and 830 and 1580m in the PFZ (54S). We examined whether spatial and temporal patterns of particulate 13Corg at the surface were preserved at depth, and also investigated the connection between the dissolved molecular CO2 concentration ([CO2(aq)]) and 13Corg in the SAZ and PFZ, including the relative importance of temperature and biological activity in controlling this relationship. 13C org of surface-water organic matter was up to 4.5 higher in the SAZ than the PFZ and underwent a seasonal increase of 2.5 (from -25.5 to -23) in the SAZ and 1.5 (from -26.5 to -25) in the PFZ. These spatial and temporal variations in 13Corg are well correlated with variations in the [CO2(aq)]. 13C org of material collected in deep-water sediment traps was also higher in the SAZ (-22) than PFZ (-24.5), with some variability but no clear seasonal change in either region. The 13Corg of organic matter reaching deep-water sediment traps (>830m) in the spring was higher than at the surface by 4 in the SAZ and 2 in the PFZ, suggesting that preferential export of some components of surface organic matter may occur or that the extent of remineralisation of sinking materials varies seasonally. However, the seasonally averaged offset between 13Corg at the surface and 13Corg in the sediment traps was similar in the two regions (1.5 and 1.8 in the SAZ and PFZ, respectively). The largest differences in 13Corg encountered here (i.e. between the SAZ and the PFZ) appear to result from temperature driven differences in CO2 solubility rather than differences in biological production. We applied these results to quantify the relative contributions of temperature, nutrient utilization, and atmospheric equilibration to glacial-interglacial 13Corg changes recorded in sediments. Cooler glacial temperatures are insufficient to maintain the high [CO2(aq)] necessary to explain observed low glacial 13Corg. Upwelling of deep-waters can sufficiently further increase [CO2(aq)], provided extensive sea-ice cover restricts air-sea equilibration, and provided nutrient utilisation is not much larger than current values. Lowered phytoplankton growth rates could also partially contribute. Reconciling these results with high glacial 15N observations suggest that some process must have affected 13Corg and 15N differentially, possibly the influence of increased glacial iron availability on nitrogen metabolism. 2003 Elsevier Ltd. All rights reserved. Article in Journal/Newspaper Sea ice Southern Ocean eCite UTAS (University of Tasmania) Southern Ocean Deep Sea Research Part I: Oceanographic Research Papers 51 2 281 305 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Oceanography Chemical Oceanography |
spellingShingle |
Earth Sciences Oceanography Chemical Oceanography Lourey, MJ Trull, T Tilbrook, B Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 |
topic_facet |
Earth Sciences Oceanography Chemical Oceanography |
description |
The carbon isotopic composition of organic matter ( 13Corg) was measured for particles suspended in surface waters (from six north-south transects across the subantarctic (SAZ) and polar frontal zones (PFZ) of the Southern Ocean south of Australia between September 1997 and March 1998), and obtained from sediment traps deployed during the same period at 1060, 2050 and 3850m depth in the SAZ (47S), 3080m under the Subantarctic Front (51S) and 830 and 1580m in the PFZ (54S). We examined whether spatial and temporal patterns of particulate 13Corg at the surface were preserved at depth, and also investigated the connection between the dissolved molecular CO2 concentration ([CO2(aq)]) and 13Corg in the SAZ and PFZ, including the relative importance of temperature and biological activity in controlling this relationship. 13C org of surface-water organic matter was up to 4.5 higher in the SAZ than the PFZ and underwent a seasonal increase of 2.5 (from -25.5 to -23) in the SAZ and 1.5 (from -26.5 to -25) in the PFZ. These spatial and temporal variations in 13Corg are well correlated with variations in the [CO2(aq)]. 13C org of material collected in deep-water sediment traps was also higher in the SAZ (-22) than PFZ (-24.5), with some variability but no clear seasonal change in either region. The 13Corg of organic matter reaching deep-water sediment traps (>830m) in the spring was higher than at the surface by 4 in the SAZ and 2 in the PFZ, suggesting that preferential export of some components of surface organic matter may occur or that the extent of remineralisation of sinking materials varies seasonally. However, the seasonally averaged offset between 13Corg at the surface and 13Corg in the sediment traps was similar in the two regions (1.5 and 1.8 in the SAZ and PFZ, respectively). The largest differences in 13Corg encountered here (i.e. between the SAZ and the PFZ) appear to result from temperature driven differences in CO2 solubility rather than differences in biological production. We applied these results to quantify the relative contributions of temperature, nutrient utilization, and atmospheric equilibration to glacial-interglacial 13Corg changes recorded in sediments. Cooler glacial temperatures are insufficient to maintain the high [CO2(aq)] necessary to explain observed low glacial 13Corg. Upwelling of deep-waters can sufficiently further increase [CO2(aq)], provided extensive sea-ice cover restricts air-sea equilibration, and provided nutrient utilisation is not much larger than current values. Lowered phytoplankton growth rates could also partially contribute. Reconciling these results with high glacial 15N observations suggest that some process must have affected 13Corg and 15N differentially, possibly the influence of increased glacial iron availability on nitrogen metabolism. 2003 Elsevier Ltd. All rights reserved. |
format |
Article in Journal/Newspaper |
author |
Lourey, MJ Trull, T Tilbrook, B |
author_facet |
Lourey, MJ Trull, T Tilbrook, B |
author_sort |
Lourey, MJ |
title |
Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 |
title_short |
Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 |
title_full |
Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 |
title_fullStr |
Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 |
title_full_unstemmed |
Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 |
title_sort |
sensitivity of δ 13 c of southern ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric co 2 |
publisher |
Elsevier Ltd |
publishDate |
2004 |
url |
https://doi.org/10.1016/j.dsr.2003.10.002 http://ecite.utas.edu.au/32062 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Sea ice Southern Ocean |
genre_facet |
Sea ice Southern Ocean |
op_relation |
http://dx.doi.org/10.1016/j.dsr.2003.10.002 Lourey, MJ and Trull, T and Tilbrook, B, Sensitivity of δ 13 C of Southern Ocean suspended and sinking organic matter to temperature, nutrient utilization, and atmospheric CO 2 , Deep-Sea Research Part 1, 51, (2) pp. 281-305. ISSN 0967-0637 (2004) [Refereed Article] http://ecite.utas.edu.au/32062 |
op_doi |
https://doi.org/10.1016/j.dsr.2003.10.002 |
container_title |
Deep Sea Research Part I: Oceanographic Research Papers |
container_volume |
51 |
container_issue |
2 |
container_start_page |
281 |
op_container_end_page |
305 |
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1766195851025186816 |