CaCO3 precipitation kinetics in waters from the Great Bahama Bank

Implications for the relationship between Bank hydrochemistry and whitings

John W. Morse, Dwight K. Gledhill, Frank J Millero

Research output: Contribution to journalArticle

87 Citations (Scopus)

Abstract

The source of whitings on the Great Bahama Bank and their relationship to major changes in the chemistry of Bank waters have been among the longest and most hotly debated topics in carbonate geochemistry. In this paper, we demonstrate that the reaction kinetics of calcite with Bank waters for a given saturation state are similar to, but somewhat slower (2 to 3 times) than with Gulf Stream water. The interpretation of the reaction kinetics of suspended Bank sediment with Bank water requires that the precipitating phase be about twice as soluble as aragonite. Good agreement at equivalent saturation states was found between experimental precipitation rates and those calculated for the rate of change of Bank water chemistry in the region of whitings. These results indicate that the dominant mode of carbonate removal is via precipitation on resuspended sediments rather than the rapid pseudo-homogeneous precipitation of calcium carbonate in the water column resulting in the formation of a whiting. Estimates indicate that single aragonite needles may be resuspended many times over a period of decades during which they experience repeated overgrowth. A major portion (>98%) of suspended calcium carbonate is outside the visually dramatic whitings. Thus, as visually spectacular as they are, whitings do not represent a short-term locally massive precipitation of carbonate on the Great Bahama Bank, nor are they even likely to be the dominant sites of carbonate removal in this region. Although future refinements are needed that include seafloor processes, we have at this point arrived at a mechanistic kinetic model that provides a reasonably quantitative explanation for the hydrochemistry of the carbonate system on the northern Great Bahama Bank.

Original languageEnglish (US)
Pages (from-to)2819-2826
Number of pages8
JournalGeochimica et Cosmochimica Acta
Volume67
Issue number15
DOIs
StatePublished - Aug 1 2003

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Hydrochemistry
hydrochemistry
Calcium Carbonate
Carbonates
carbonate
kinetics
Kinetics
Water
reaction kinetics
aragonite
calcium carbonate
saturation
Reaction kinetics
carbonate system
water
Sediments
water chemistry
sediment
Geochemistry
calcite

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

CaCO3 precipitation kinetics in waters from the Great Bahama Bank : Implications for the relationship between Bank hydrochemistry and whitings. / Morse, John W.; Gledhill, Dwight K.; Millero, Frank J.

In: Geochimica et Cosmochimica Acta, Vol. 67, No. 15, 01.08.2003, p. 2819-2826.

Research output: Contribution to journalArticle

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