Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera
To understand bottom water variability in the subtropical northwestern Pacific, bottom water temperatures (BWTs), carbon isotopes (δ 13 C), and oxygen isotopes of seawater (δ 18 O w ) at a water depth of 1166 m were reconstructed from 26 kyr BP to present. A new regional Mg / Ca calibration for the...
Published in: | Climate of the Past |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2015
|
Subjects: | |
Online Access: | https://doi.org/10.5194/cp-11-803-2015 https://doaj.org/article/082754c9de2c47869a4020d6bfa76042 |
id |
ftdoajarticles:oai:doaj.org/article:082754c9de2c47869a4020d6bfa76042 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:082754c9de2c47869a4020d6bfa76042 2023-05-15T17:52:43+02:00 Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera Y. Kubota K. Kimoto T. Itaki Y. Yokoyama Y. Miyairi H. Matsuzaki 2015-06-01T00:00:00Z https://doi.org/10.5194/cp-11-803-2015 https://doaj.org/article/082754c9de2c47869a4020d6bfa76042 EN eng Copernicus Publications http://www.clim-past.net/11/803/2015/cp-11-803-2015.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-11-803-2015 https://doaj.org/article/082754c9de2c47869a4020d6bfa76042 Climate of the Past, Vol 11, Iss 6, Pp 803-824 (2015) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2015 ftdoajarticles https://doi.org/10.5194/cp-11-803-2015 2022-12-31T05:50:21Z To understand bottom water variability in the subtropical northwestern Pacific, bottom water temperatures (BWTs), carbon isotopes (δ 13 C), and oxygen isotopes of seawater (δ 18 O w ) at a water depth of 1166 m were reconstructed from 26 kyr BP to present. A new regional Mg / Ca calibration for the benthic foraminifera Cibicidoides wuellerstorfi (type B) was established to convert the benthic Mg / Ca value to BWT, based on 26 surface sediment samples and two core-top samples retrieved around Okinawa Island. During the Last Glacial Maximum (LGM), the δ 18 O w in the intermediate water in the northwestern South Pacific was ~0.4‰ lower than in the deep South Pacific, indicating a greater vertical salinity gradient than at present. This salinity (and probably density) structure would have led to stratification in the intermediate and deep Pacific, which would, in turn, have greatly influenced carbon storage during the glacial time. The benthic Mg / Ca and δ 18 O w records suggest changes that seem to follow Heinrich event 1 (H1) and the Bølling–Alleød (B/A) and Younger Dryas (YD) intervals, with BWT higher during H1 (~17 kyr BP) and YD (~12 kyr BP) and lower during B/A (~14 kyr BP). The warming in the bottom water during H1 suggests increased contribution of North Pacific Intermediate Water (NPIW) to the subtropical northwestern Pacific and decreased upwelling of cooler waters from the abyssal North Pacific. During the interval from 17 to 14.5 kyr BP, the BWT tended to decrease successively in association with a decrease in δ 13 C values, presumably as a result of increased upwelling of the abyssal waters to the intermediate depths of the North Pacific caused by shoaling and enhancement of the southward return flow of Pacific Deep Water (PDW). During the Holocene, the millennial- to sub-millennial-scale variations in the BWT generally correlate with the sea surface temperatures in the Okhotsk Sea, the source region of the NPIW, suggesting that changes in the BWT are linked to changes in the NPIW production rate. Article in Journal/Newspaper okhotsk sea Directory of Open Access Journals: DOAJ Articles Okhotsk Pacific Climate of the Past 11 6 803 824 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
spellingShingle |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 Y. Kubota K. Kimoto T. Itaki Y. Yokoyama Y. Miyairi H. Matsuzaki Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
To understand bottom water variability in the subtropical northwestern Pacific, bottom water temperatures (BWTs), carbon isotopes (δ 13 C), and oxygen isotopes of seawater (δ 18 O w ) at a water depth of 1166 m were reconstructed from 26 kyr BP to present. A new regional Mg / Ca calibration for the benthic foraminifera Cibicidoides wuellerstorfi (type B) was established to convert the benthic Mg / Ca value to BWT, based on 26 surface sediment samples and two core-top samples retrieved around Okinawa Island. During the Last Glacial Maximum (LGM), the δ 18 O w in the intermediate water in the northwestern South Pacific was ~0.4‰ lower than in the deep South Pacific, indicating a greater vertical salinity gradient than at present. This salinity (and probably density) structure would have led to stratification in the intermediate and deep Pacific, which would, in turn, have greatly influenced carbon storage during the glacial time. The benthic Mg / Ca and δ 18 O w records suggest changes that seem to follow Heinrich event 1 (H1) and the Bølling–Alleød (B/A) and Younger Dryas (YD) intervals, with BWT higher during H1 (~17 kyr BP) and YD (~12 kyr BP) and lower during B/A (~14 kyr BP). The warming in the bottom water during H1 suggests increased contribution of North Pacific Intermediate Water (NPIW) to the subtropical northwestern Pacific and decreased upwelling of cooler waters from the abyssal North Pacific. During the interval from 17 to 14.5 kyr BP, the BWT tended to decrease successively in association with a decrease in δ 13 C values, presumably as a result of increased upwelling of the abyssal waters to the intermediate depths of the North Pacific caused by shoaling and enhancement of the southward return flow of Pacific Deep Water (PDW). During the Holocene, the millennial- to sub-millennial-scale variations in the BWT generally correlate with the sea surface temperatures in the Okhotsk Sea, the source region of the NPIW, suggesting that changes in the BWT are linked to changes in the NPIW production rate. |
format |
Article in Journal/Newspaper |
author |
Y. Kubota K. Kimoto T. Itaki Y. Yokoyama Y. Miyairi H. Matsuzaki |
author_facet |
Y. Kubota K. Kimoto T. Itaki Y. Yokoyama Y. Miyairi H. Matsuzaki |
author_sort |
Y. Kubota |
title |
Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera |
title_short |
Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera |
title_full |
Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera |
title_fullStr |
Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera |
title_full_unstemmed |
Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera |
title_sort |
bottom water variability in the subtropical northwestern pacific from 26 kyr bp to present based on mg / ca and stable carbon and oxygen isotopes of benthic foraminifera |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/cp-11-803-2015 https://doaj.org/article/082754c9de2c47869a4020d6bfa76042 |
geographic |
Okhotsk Pacific |
geographic_facet |
Okhotsk Pacific |
genre |
okhotsk sea |
genre_facet |
okhotsk sea |
op_source |
Climate of the Past, Vol 11, Iss 6, Pp 803-824 (2015) |
op_relation |
http://www.clim-past.net/11/803/2015/cp-11-803-2015.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-11-803-2015 https://doaj.org/article/082754c9de2c47869a4020d6bfa76042 |
op_doi |
https://doi.org/10.5194/cp-11-803-2015 |
container_title |
Climate of the Past |
container_volume |
11 |
container_issue |
6 |
container_start_page |
803 |
op_container_end_page |
824 |
_version_ |
1766160411308064768 |