Oxygen Minimum Zone Contrasts Between the Arabian Sea and the Bay of Bengal Implied by Differences in Remineralization Depth

Muchamad Al Azhar, Zouhair Lachkhar, Marina Lévy, Kendall Shafer-Smith

Research output: Contribution to journalArticle

Abstract

The combination of high primary productivity and weak ventilation in the Arabian Sea (AS) and Bay of Bengal (BoB) generates vast areas of depleted oxygen, known as oxygen minimum zones (OMZs). The AS OMZ is the world's thickest and hosts up to 40% of global denitrification. In contrast, the OMZ in the BoB is weaker and denitrification free. Using a series of model simulations, we show that the deeper remineralization depth (RD) in the BoB, potentially associated with organic matter aggregation with riverine mineral particles, contributes to weaken its OMZ. When the RD is set uniformly across both seas, the model fails to reproduce the observed contrast between the two OMZs, irrespective of the chosen RD. In contrast, when the RD is allowed to vary spatially, the contrasting distributions of oxygen and nitrate are correctly reproduced, and water column denitrification is simulated exclusively in the AS, in agreement with observations.

Original languageEnglish (US)
Pages (from-to)11,106-11,114
JournalGeophysical Research Letters
Volume44
Issue number21
DOIs
StatePublished - Nov 16 2017

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Arabian Sea
remineralization
oxygen
denitrification
ventilation
sea
productivity
nitrates
water column
minerals
nitrate
organic matter
mineral

Keywords

  • biogeochemical cycles
  • denitrification
  • oxygen minimum zones
  • remineralization depth
  • the Arabian Sea
  • the Bay of Bengal

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

Oxygen Minimum Zone Contrasts Between the Arabian Sea and the Bay of Bengal Implied by Differences in Remineralization Depth. / Al Azhar, Muchamad; Lachkhar, Zouhair; Lévy, Marina; Shafer-Smith, Kendall.

In: Geophysical Research Letters, Vol. 44, No. 21, 16.11.2017, p. 11,106-11,114.

Research output: Contribution to journalArticle

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N2 - The combination of high primary productivity and weak ventilation in the Arabian Sea (AS) and Bay of Bengal (BoB) generates vast areas of depleted oxygen, known as oxygen minimum zones (OMZs). The AS OMZ is the world's thickest and hosts up to 40% of global denitrification. In contrast, the OMZ in the BoB is weaker and denitrification free. Using a series of model simulations, we show that the deeper remineralization depth (RD) in the BoB, potentially associated with organic matter aggregation with riverine mineral particles, contributes to weaken its OMZ. When the RD is set uniformly across both seas, the model fails to reproduce the observed contrast between the two OMZs, irrespective of the chosen RD. In contrast, when the RD is allowed to vary spatially, the contrasting distributions of oxygen and nitrate are correctly reproduced, and water column denitrification is simulated exclusively in the AS, in agreement with observations.

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