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Isotopic disequilibrium during uptake of atmospheric CO2 into mine process waters: implications for CO2 sequestration

journal contribution
posted on 2023-05-19, 23:00 authored by Wilson, SA, Shaun BarkerShaun Barker, Dipple, GM, Atudorei, V
Dypingite, a hydrated Mg-carbonate mineral, was precipitated from high-pH, high salinity solutions to investigate controls on carbon fixation and to identify the isotopic characteristics of mineral sequestration in mine tailings. δ13C values of dissolved inorganic carbon content and synthetic dypingite are significantly more negative than those predicted for equilibrium exchange of CO2 gas between the atmosphere and solution. The measured δ13C of aqueous carbonate species is consistent with a kinetic fractionation that results from a slow diffusion of atmospheric CO2 into solution. During dypingite precipitation, dissolved inorganic carbon concentrations decrease and δ13C values become more negative, indicating that the rate of CO2 uptake into solution was outpaced by the rate of carbon fixation within the precipitate. This implies that CO2 gas uptake is rate-limiting to CO2 fixation. δ13C of carbonate mineral precipitates in mine tailings and of DIC in mine process waters display similar 13C-depletions that are inconsistent with equilibrium fractionation. Thus, the rate of carbon fixation in mine tailings may also be limited by supply of CO2. Carbon sequestration could be accelerated by increasing the partial pressure of CO2 in tailings ponds or by using chemicals that enhance the uptake of gaseous CO2 into aqueous solution.


Publication title

Environmental Science and Technology










School of Natural Sciences


Amer Chemical Soc

Place of publication

1155 16Th St, Nw, Washington, USA, Dc, 20036

Rights statement

Copyright 2010 American Chemical Society

Repository Status

  • Restricted

Socio-economic Objectives

Climate change mitigation strategies; Expanding knowledge in the earth sciences

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