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The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific : Implications for silicate cycling during the Last Glacial Maximum

Xiong, Zhifang ; Li, Tiegang ; Algeo, Thomas ; Doering, Kristin LU orcid ; Frank, Martin ; Brzezinski, Mark A. ; Chang, Fengming ; Opfergelt, Sophie ; Crosta, Xavier and Jiang, Fuqing , et al. (2015) In Paleoceanography 30(7). p.803-823
Abstract

The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (δ30SiE. rex) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, δ30SiE. rex varies from -1.23‰ to -0.83‰ (average -1.04‰), a range that is atypical of marine diatom δ30Si and that corresponds to the lower limit of reported diatom δ30Si values of any age. A binary... (More)

The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (δ30SiE. rex) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, δ30SiE. rex varies from -1.23‰ to -0.83‰ (average -1.04‰), a range that is atypical of marine diatom δ30Si and that corresponds to the lower limit of reported diatom δ30Si values of any age. A binary mixing model (upwelled silicon versus eolian silicon) accounting for silicon isotopic fractionation during DSi uptake by diatoms was constructed. The binary mixing model demonstrates that E. rex dominantly utilized DSi from eolian sources (i.e., Asian dust) with only minor contributions from upwelled seawater sources (i.e., advected from Subantarctic Mode Water, Antarctic Intermediate Water, or North Pacific Intermediate Water). E. rex utilized only ∼24% of available DSi, indicating that surface waters of the EPS were eutrophic with respect to silicon during the LGM. Our results suggest that giant diatoms did not always use a buoyancy strategy to obtain nutrients from the deep nutrient pool, thus revising previously proposed models for the formation of E. rex LDMs.

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publishing date
type
Contribution to journal
publication status
published
subject
keywords
deep chlorophyll maximum, eolian dust, giant diatoms, marine productivity, seawater silicon, silicon isotopes
in
Paleoceanography
volume
30
issue
7
pages
21 pages
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:84939259333
ISSN
0883-8305
DOI
10.1002/2015PA002793
language
English
LU publication?
no
additional info
Publisher Copyright: ©2015. American Geophysical Union. All Rights Reserved.
id
cfe04235-1c86-4e98-a6b3-ef1fa1147bd7
date added to LUP
2022-09-05 12:42:59
date last changed
2023-04-18 22:24:10
@article{cfe04235-1c86-4e98-a6b3-ef1fa1147bd7,
  abstract     = {{<p>The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (δ<sup>30</sup>Si<sub>E. rex</sub>) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, δ<sup>30</sup>Si<sub>E. rex</sub> varies from -1.23‰ to -0.83‰ (average -1.04‰), a range that is atypical of marine diatom δ<sup>30</sup>Si and that corresponds to the lower limit of reported diatom δ<sup>30</sup>Si values of any age. A binary mixing model (upwelled silicon versus eolian silicon) accounting for silicon isotopic fractionation during DSi uptake by diatoms was constructed. The binary mixing model demonstrates that E. rex dominantly utilized DSi from eolian sources (i.e., Asian dust) with only minor contributions from upwelled seawater sources (i.e., advected from Subantarctic Mode Water, Antarctic Intermediate Water, or North Pacific Intermediate Water). E. rex utilized only ∼24% of available DSi, indicating that surface waters of the EPS were eutrophic with respect to silicon during the LGM. Our results suggest that giant diatoms did not always use a buoyancy strategy to obtain nutrients from the deep nutrient pool, thus revising previously proposed models for the formation of E. rex LDMs.</p>}},
  author       = {{Xiong, Zhifang and Li, Tiegang and Algeo, Thomas and Doering, Kristin and Frank, Martin and Brzezinski, Mark A. and Chang, Fengming and Opfergelt, Sophie and Crosta, Xavier and Jiang, Fuqing and Wan, Shiming and Zhai, Bin}},
  issn         = {{0883-8305}},
  keywords     = {{deep chlorophyll maximum; eolian dust; giant diatoms; marine productivity; seawater silicon; silicon isotopes}},
  language     = {{eng}},
  month        = {{07}},
  number       = {{7}},
  pages        = {{803--823}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Paleoceanography}},
  title        = {{The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific : Implications for silicate cycling during the Last Glacial Maximum}},
  url          = {{http://dx.doi.org/10.1002/2015PA002793}},
  doi          = {{10.1002/2015PA002793}},
  volume       = {{30}},
  year         = {{2015}},
}