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A novel determination of calcite dissolution kinetics in seawater

Subhas, Adam V. and Rollins, Nick E. and Berelson, William M. and Dong, Sijia and Erez, Jonathan and Adkins, Jess F. (2015) A novel determination of calcite dissolution kinetics in seawater. Geochimica et Cosmochimica Acta, 170 . pp. 51-68. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20150914-094735715

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Abstract

We present a novel determination of the dissolution kinetics of inorganic calcite in seawater. We dissolved ^(13)C-labeled calcite in unlabeled seawater, and traced the evolving δ^(13)C composition of the fluid over time to establish dissolution rates. This method provides sensitive determinations of dissolution rate, which we couple with tight constraints on both seawater saturation state and surface area of the dissolving minerals. We have determined dissolution rates for two different abiotic calcite materials and three different grain sizes. Near-equilibrium dissolution rates are highly nonlinear, and are well normalized by geometric surface area, giving an empirical dissolution rate dependence on saturation state (Ω) of: Rate (g/cm^2/day) = 7.2 ± 0.6 · 10^(-4) (1-Ω)^(3.9±0.1). This result substantiates the non-linear response of calcite dissolution to undersaturation. The bulk dissolution rate constant calculated here is in excellent agreement with those determined in far from equilibrium and dilute solution experiments. Plots of dissolution versus undersaturation indicates the presence of at least two dissolution mechanisms, implying a criticality in the calcite-seawater system. Finally, our new rate determination has implications for modeling of pelagic and seafloor dissolution. Nonlinear dissolution kinetics in a simple 1-D lysocline model indicate a possible transition from kinetic to diffusive control with increasing water depth, and also confirm the importance of respiration-driven dissolution in setting the shape of the calcite lysocline.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.gca.2015.08.011DOIArticle
http://www.sciencedirect.com/science/article/pii/S0016703715005050PublisherArticle
ORCID:
AuthorORCID
Subhas, Adam V.0000-0002-7688-6624
Dong, Sijia0000-0002-5811-9333
Adkins, Jess F.0000-0002-3174-5190
Additional Information:© 2015 Elsevier Ltd. Received 2 January 2015; accepted in revised form 11 August 2015; Available online 31 August 2015. The authors would like to acknowledge Eric Kleinsasser and Joel Schmidt for help with BET analysis, and Burke Hales for helpful suggestions regarding the solubility of calcites. We also thank the three anonymous reviewers for their comments and criticisms on the original manuscript drafts. This work was supported by an NSF Ocean Acidification grant (numbers OCE1220600 and OCE1220302) and the NSF Graduate Research Fellowship.
Funders:
Funding AgencyGrant Number
NSFOCE-1220600
NSFOCE-1220302
NSF Graduate Research FellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20150914-094735715
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150914-094735715
Official Citation:Adam V. Subhas, Nick E. Rollins, William M. Berelson, Sijia Dong, Jonathan Erez, Jess F. Adkins, A novel determination of calcite dissolution kinetics in seawater, Geochimica et Cosmochimica Acta, Volume 170, 1 December 2015, Pages 51-68, ISSN 0016-7037, http://dx.doi.org/10.1016/j.gca.2015.08.011. (http://www.sciencedirect.com/science/article/pii/S0016703715005050)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60223
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Sep 2015 17:20
Last Modified:24 Oct 2019 17:04

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