A switch from Si(OH)4 to NO-3 depletion in the glacial Southern Ocean

Mark A. Brzezinski; Carol J. Pride; Valerie M. Franck; Daniel M. Sigman; Jorge L. Sarmiento; Katsumi Matsumoto; Nicolas Gruber; Greg H. Rau; Kenneth H. Coale

doi:10.1029/2001gl014349

A switch from Si(OH)₄ to NO^-₃ depletion in the glacial Southern Ocean

Mark A. Brzezinski, Carol J. Pride, Valerie M. Franck, Daniel M. Sigman, Jorge L. Sarmiento, Katsumi Matsumoto, Nicolas Gruber, Greg H. Rau, Kenneth H. Coale

Research output: Contribution to journal › Article › peer-review

279 Scopus citations

Abstract

Phytoplankton in the Antarctic deplete silicic acid (Si(OH)₄) to a far greater extent than they do nitrate (NO₃^-). This pattern can be reversed by the addition of iron which dramatically lowers diatom Si(OH)₄:NO₃^- uptake ratios. Higher iron supply during glacial times would thus drive the Antarctic towards NO₃^- depletion with excess Si(OH)₄ remaining in surface waters. New δ³⁰Si and δ¹⁵N records from Antarctic sediments confirm diminished Si(OH)₄ use and enhanced NO₃^- depletion during the last three glaciations. The present low-Si(OH)₄ water is transported northward to at least the subtropics. We postulate that the glacial high-Si(OH)₄ water similarly may have been transported to the subtropics and beyond. This input of Si(OH)₄ may have caused diatoms to displace coccolithophores at low latitudes, weakening the carbonate pump and increasing the depth of organic matter remineralization. These effects may have lowered glacial atmospheric pCO₂ by as much as 60 ppm.

Original language	English (US)
Pages (from-to)	5-1 - 5-4
Journal	Geophysical Research Letters
Volume	29
Issue number	12
DOIs	https://doi.org/10.1029/2001gl014349
State	Published - Jun 15 2002
Externally published	Yes

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title = "A switch from Si(OH)4 to NO-3 depletion in the glacial Southern Ocean",

abstract = "Phytoplankton in the Antarctic deplete silicic acid (Si(OH)4) to a far greater extent than they do nitrate (NO3-). This pattern can be reversed by the addition of iron which dramatically lowers diatom Si(OH)4:NO3- uptake ratios. Higher iron supply during glacial times would thus drive the Antarctic towards NO3- depletion with excess Si(OH)4 remaining in surface waters. New δ30Si and δ15N records from Antarctic sediments confirm diminished Si(OH)4 use and enhanced NO3- depletion during the last three glaciations. The present low-Si(OH)4 water is transported northward to at least the subtropics. We postulate that the glacial high-Si(OH)4 water similarly may have been transported to the subtropics and beyond. This input of Si(OH)4 may have caused diatoms to displace coccolithophores at low latitudes, weakening the carbonate pump and increasing the depth of organic matter remineralization. These effects may have lowered glacial atmospheric pCO2 by as much as 60 ppm.",

author = "Brzezinski, {Mark A.} and Pride, {Carol J.} and Franck, {Valerie M.} and Sigman, {Daniel M.} and Sarmiento, {Jorge L.} and Katsumi Matsumoto and Nicolas Gruber and Rau, {Greg H.} and Coale, {Kenneth H.}",

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T1 - A switch from Si(OH)4 to NO-3 depletion in the glacial Southern Ocean

AU - Brzezinski, Mark A.

AU - Pride, Carol J.

AU - Franck, Valerie M.

AU - Sigman, Daniel M.

AU - Sarmiento, Jorge L.

AU - Matsumoto, Katsumi

AU - Gruber, Nicolas

AU - Rau, Greg H.

AU - Coale, Kenneth H.

PY - 2002/6/15

Y1 - 2002/6/15

N2 - Phytoplankton in the Antarctic deplete silicic acid (Si(OH)4) to a far greater extent than they do nitrate (NO3-). This pattern can be reversed by the addition of iron which dramatically lowers diatom Si(OH)4:NO3- uptake ratios. Higher iron supply during glacial times would thus drive the Antarctic towards NO3- depletion with excess Si(OH)4 remaining in surface waters. New δ30Si and δ15N records from Antarctic sediments confirm diminished Si(OH)4 use and enhanced NO3- depletion during the last three glaciations. The present low-Si(OH)4 water is transported northward to at least the subtropics. We postulate that the glacial high-Si(OH)4 water similarly may have been transported to the subtropics and beyond. This input of Si(OH)4 may have caused diatoms to displace coccolithophores at low latitudes, weakening the carbonate pump and increasing the depth of organic matter remineralization. These effects may have lowered glacial atmospheric pCO2 by as much as 60 ppm.

AB - Phytoplankton in the Antarctic deplete silicic acid (Si(OH)4) to a far greater extent than they do nitrate (NO3-). This pattern can be reversed by the addition of iron which dramatically lowers diatom Si(OH)4:NO3- uptake ratios. Higher iron supply during glacial times would thus drive the Antarctic towards NO3- depletion with excess Si(OH)4 remaining in surface waters. New δ30Si and δ15N records from Antarctic sediments confirm diminished Si(OH)4 use and enhanced NO3- depletion during the last three glaciations. The present low-Si(OH)4 water is transported northward to at least the subtropics. We postulate that the glacial high-Si(OH)4 water similarly may have been transported to the subtropics and beyond. This input of Si(OH)4 may have caused diatoms to displace coccolithophores at low latitudes, weakening the carbonate pump and increasing the depth of organic matter remineralization. These effects may have lowered glacial atmospheric pCO2 by as much as 60 ppm.

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A switch from Si(OH)₄ to NO^-₃ depletion in the glacial Southern Ocean

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