Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline
The cycling and transport of dissolved silicon (Si) in the ocean may be traced by its stable isotope composition, δ 30 Si. We present a dataset of δ 30 Si values along 103° W in the eastern South Pacific Ocean, ranging from the Antarctic Zone of the Southern Ocean (62° S) to the equatorial Pacific (...
Published in: | Biogeosciences |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2012
|
Subjects: | |
Online Access: | https://doi.org/10.5194/bg-9-4199-2012 https://doaj.org/article/ba59b91c80204bdf86327bd7538f7977 |
id |
ftdoajarticles:oai:doaj.org/article:ba59b91c80204bdf86327bd7538f7977 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:ba59b91c80204bdf86327bd7538f7977 2023-05-15T13:50:34+02:00 Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline G. F. de Souza B. C. Reynolds G. C. Johnson J. L. Bullister B. Bourdon 2012-11-01T00:00:00Z https://doi.org/10.5194/bg-9-4199-2012 https://doaj.org/article/ba59b91c80204bdf86327bd7538f7977 EN eng Copernicus Publications http://www.biogeosciences.net/9/4199/2012/bg-9-4199-2012.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-9-4199-2012 1726-4170 1726-4189 https://doaj.org/article/ba59b91c80204bdf86327bd7538f7977 Biogeosciences, Vol 9, Iss 11, Pp 4199-4213 (2012) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2012 ftdoajarticles https://doi.org/10.5194/bg-9-4199-2012 2022-12-31T02:47:56Z The cycling and transport of dissolved silicon (Si) in the ocean may be traced by its stable isotope composition, δ 30 Si. We present a dataset of δ 30 Si values along 103° W in the eastern South Pacific Ocean, ranging from the Antarctic Zone of the Southern Ocean (62° S) to the equatorial Pacific (12° S). At high southern latitudes, the uptake and associated isotope fractionation of Si by diatoms results in highly elevated δ 30 Si values (up to +3.2‰) in the summer mixed layer. High δ 30 Si values (+2‰) are also preserved in the high-latitude fossil winter mixed layer, documenting the efficient export of diatom opal beyond the maximum depth of winter convection. This elevated winter mixed layer δ 30 Si signature is introduced into the ocean interior by the subduction of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW), whose northward spreading results in a strong isopycnal control on lower-thermocline and intermediate δ 30 Si values in the well-ventilated eastern South Pacific. Values of δ 30 Si are strongly conserved along SAMW and AAIW density levels as far north as 26° S, documenting the importance of the export of preformed Si from the surface Southern Ocean to lower latitudes. In contrast, in the equatorial Pacific, depressed δ 30 Si values in the mesopelagic ocean are observed, most likely documenting the combined influence of a North Pacific Si source as well as the accumulation of remineralized Si within the eastern equatorial Pacific shadow zone. At depth, δ 30 Si values in the South Pacific remain indistinguishable from deep Southern Ocean values of +1.25‰, even within Si-rich and oxygen-poor deep waters returning from the North Pacific. This homogeneity implies that the dissolution of opal plays a negligible role in altering the δ 30 Si value of deep waters as they traverse the deep Pacific Ocean. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean The Antarctic Pacific Biogeosciences 9 11 4199 4213 |
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 G. F. de Souza B. C. Reynolds G. C. Johnson J. L. Bullister B. Bourdon Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The cycling and transport of dissolved silicon (Si) in the ocean may be traced by its stable isotope composition, δ 30 Si. We present a dataset of δ 30 Si values along 103° W in the eastern South Pacific Ocean, ranging from the Antarctic Zone of the Southern Ocean (62° S) to the equatorial Pacific (12° S). At high southern latitudes, the uptake and associated isotope fractionation of Si by diatoms results in highly elevated δ 30 Si values (up to +3.2‰) in the summer mixed layer. High δ 30 Si values (+2‰) are also preserved in the high-latitude fossil winter mixed layer, documenting the efficient export of diatom opal beyond the maximum depth of winter convection. This elevated winter mixed layer δ 30 Si signature is introduced into the ocean interior by the subduction of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW), whose northward spreading results in a strong isopycnal control on lower-thermocline and intermediate δ 30 Si values in the well-ventilated eastern South Pacific. Values of δ 30 Si are strongly conserved along SAMW and AAIW density levels as far north as 26° S, documenting the importance of the export of preformed Si from the surface Southern Ocean to lower latitudes. In contrast, in the equatorial Pacific, depressed δ 30 Si values in the mesopelagic ocean are observed, most likely documenting the combined influence of a North Pacific Si source as well as the accumulation of remineralized Si within the eastern equatorial Pacific shadow zone. At depth, δ 30 Si values in the South Pacific remain indistinguishable from deep Southern Ocean values of +1.25‰, even within Si-rich and oxygen-poor deep waters returning from the North Pacific. This homogeneity implies that the dissolution of opal plays a negligible role in altering the δ 30 Si value of deep waters as they traverse the deep Pacific Ocean. |
format |
Article in Journal/Newspaper |
author |
G. F. de Souza B. C. Reynolds G. C. Johnson J. L. Bullister B. Bourdon |
author_facet |
G. F. de Souza B. C. Reynolds G. C. Johnson J. L. Bullister B. Bourdon |
author_sort |
G. F. de Souza |
title |
Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline |
title_short |
Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline |
title_full |
Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline |
title_fullStr |
Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline |
title_full_unstemmed |
Silicon stable isotope distribution traces Southern Ocean export of Si to the eastern South Pacific thermocline |
title_sort |
silicon stable isotope distribution traces southern ocean export of si to the eastern south pacific thermocline |
publisher |
Copernicus Publications |
publishDate |
2012 |
url |
https://doi.org/10.5194/bg-9-4199-2012 https://doaj.org/article/ba59b91c80204bdf86327bd7538f7977 |
geographic |
Antarctic Southern Ocean The Antarctic Pacific |
geographic_facet |
Antarctic Southern Ocean The Antarctic Pacific |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Biogeosciences, Vol 9, Iss 11, Pp 4199-4213 (2012) |
op_relation |
http://www.biogeosciences.net/9/4199/2012/bg-9-4199-2012.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-9-4199-2012 1726-4170 1726-4189 https://doaj.org/article/ba59b91c80204bdf86327bd7538f7977 |
op_doi |
https://doi.org/10.5194/bg-9-4199-2012 |
container_title |
Biogeosciences |
container_volume |
9 |
container_issue |
11 |
container_start_page |
4199 |
op_container_end_page |
4213 |
_version_ |
1766253735361642496 |