Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean: Implications for carbon flux

Kendra L. Daly, Walker O. Smith, Gregory C. Johnson, Giacomo R. DiTullio, David R. Jones, Calvin W. Mordy, Richard A. Feely, Dennis A Hansell, Jia Zhong Zhang

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

We investigated the hydrography, nutrients, and dissolved and participate carbon pools in the western Pacific sector of the Antarctic Circumpolar Current (ACC) during austral summer 1996 to assess the region's role in the carbon cycle. Low fCO2 values along two transects indicated that much of the study area was a sink for atmospheric CO2. The fCO2 values were lowest near the Polar Front (PF) and the Subtropical Front (STF), concomitant with maxima of chlorophyll a and particulate and dissolved organic carbon. The largest biomass accumulations did not occur at fronts, which had high surface geostrophic velocities (20-51 cm s-1), but in relatively low velocity regions near fronts or in an eddy. Thus vertical motion and horizontal advection associated with fronts may have replenished nutrients in surface waters but also dispersed phytoplankton. Although surface waters north of the PF have been characterized as a "high nutrient-low chlorophyll" region, low silicic acid (Si) concentrations (2-4 μM) may limit production of large diatoms and therefore the potential carbon flux. Low concentrations (4-10 μM Si) at depths of winter mixing constrain the level of Si replenishment to surface waters. It has been suggested that an increase in aeolian iron north of the PF may increase primary productivity and carbon export. Our results, however, indicate that while diatom growth and carbon export may be enhanced, the extent ultimately would be limited by the vertical supply of Si. South of the PF, the primary mechanism by which carbon is exported to deep water appears to be through diatom flux. We suggest that north of the PF, particulate and dissolved carbon may be exported primarily to intermediate depths through subduction and diapycnal mixing associated with Subantarctic Mode Water and Antarctic Intermediate Water formation. These physical-biological interactions and Si dynamics should be included in future biogeochemical models to provide a more accurate prediction of carbon flux.

Original languageEnglish (US)
Article number1999JC000090
Pages (from-to)7107-7124
Number of pages18
JournalJournal of Geophysical Research C: Oceans
Volume106
Issue numberC4
StatePublished - Apr 15 2001

Fingerprint

hydrography
silicic acid
polar front
nutrients
carbon flux
Nutrients
Silicic Acid
oceans
sectors
Carbon
Fluxes
nutrient
carbon
ocean
diatom
surface water
Surface waters
algae
acids
Antarctic Intermediate Water

ASJC Scopus subject areas

  • Oceanography
  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics

Cite this

Daly, K. L., Smith, W. O., Johnson, G. C., DiTullio, G. R., Jones, D. R., Mordy, C. W., ... Zhang, J. Z. (2001). Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean: Implications for carbon flux. Journal of Geophysical Research C: Oceans, 106(C4), 7107-7124. [1999JC000090].

Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean : Implications for carbon flux. / Daly, Kendra L.; Smith, Walker O.; Johnson, Gregory C.; DiTullio, Giacomo R.; Jones, David R.; Mordy, Calvin W.; Feely, Richard A.; Hansell, Dennis A; Zhang, Jia Zhong.

In: Journal of Geophysical Research C: Oceans, Vol. 106, No. C4, 1999JC000090, 15.04.2001, p. 7107-7124.

Research output: Contribution to journalArticle

Daly, KL, Smith, WO, Johnson, GC, DiTullio, GR, Jones, DR, Mordy, CW, Feely, RA, Hansell, DA & Zhang, JZ 2001, 'Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean: Implications for carbon flux', Journal of Geophysical Research C: Oceans, vol. 106, no. C4, 1999JC000090, pp. 7107-7124.
Daly KL, Smith WO, Johnson GC, DiTullio GR, Jones DR, Mordy CW et al. Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean: Implications for carbon flux. Journal of Geophysical Research C: Oceans. 2001 Apr 15;106(C4):7107-7124. 1999JC000090.
Daly, Kendra L. ; Smith, Walker O. ; Johnson, Gregory C. ; DiTullio, Giacomo R. ; Jones, David R. ; Mordy, Calvin W. ; Feely, Richard A. ; Hansell, Dennis A ; Zhang, Jia Zhong. / Hydrography, nutrients, and carbon pools in the Pacific sector of the Southern Ocean : Implications for carbon flux. In: Journal of Geophysical Research C: Oceans. 2001 ; Vol. 106, No. C4. pp. 7107-7124.
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abstract = "We investigated the hydrography, nutrients, and dissolved and participate carbon pools in the western Pacific sector of the Antarctic Circumpolar Current (ACC) during austral summer 1996 to assess the region's role in the carbon cycle. Low fCO2 values along two transects indicated that much of the study area was a sink for atmospheric CO2. The fCO2 values were lowest near the Polar Front (PF) and the Subtropical Front (STF), concomitant with maxima of chlorophyll a and particulate and dissolved organic carbon. The largest biomass accumulations did not occur at fronts, which had high surface geostrophic velocities (20-51 cm s-1), but in relatively low velocity regions near fronts or in an eddy. Thus vertical motion and horizontal advection associated with fronts may have replenished nutrients in surface waters but also dispersed phytoplankton. Although surface waters north of the PF have been characterized as a {"}high nutrient-low chlorophyll{"} region, low silicic acid (Si) concentrations (2-4 μM) may limit production of large diatoms and therefore the potential carbon flux. Low concentrations (4-10 μM Si) at depths of winter mixing constrain the level of Si replenishment to surface waters. It has been suggested that an increase in aeolian iron north of the PF may increase primary productivity and carbon export. Our results, however, indicate that while diatom growth and carbon export may be enhanced, the extent ultimately would be limited by the vertical supply of Si. South of the PF, the primary mechanism by which carbon is exported to deep water appears to be through diatom flux. We suggest that north of the PF, particulate and dissolved carbon may be exported primarily to intermediate depths through subduction and diapycnal mixing associated with Subantarctic Mode Water and Antarctic Intermediate Water formation. These physical-biological interactions and Si dynamics should be included in future biogeochemical models to provide a more accurate prediction of carbon flux.",
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AU - DiTullio, Giacomo R.

AU - Jones, David R.

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AU - Feely, Richard A.

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