Carbon dioxide retention and carbon exchange on unsaturated Quaternary sediments

Robert G. Striegl; D.E. Armstrong

doi:10.1016/0016-7037(90)90051-l

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Carbon dioxide retention and carbon exchange on unsaturated Quaternary sediments

Robert G. Striegl·D.E. Armstrong

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Abstract

Retention of CO 2 on three air-dried and partly water-saturated glacial and eolian sediments was measured at 20°C for a range in, P CO 2 that commonly occurs in unsaturated zones. Ratios of the relative losses of CO 2 and 14 CO 2 from a surrogate atmosphere overlying the sediments were 1:1 for the dry condition. For the wet condition, those relative losses were generally ⪯ 1:2, indicating bicarbonateion formation and C-isotope exchange. Mass losses of CO 2 per surface area of sediment were similar for dry and wet conditions; however, CO 2 losses for the wet condition were 8 to 17 times greater than losses predicted by calcite equilibria. Occurrence of this comparatively large reservoir of immobile, exchangeable C in unsaturated zones can cause alteration of the C-isotope composition of soil CO 2 and of dissolved inorganic C in interstitial water, and needs to be considered when modeling 14 CO 2 movement in the unsaturated zone or when interpreting radiocarbon ages of infiltrating water.

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Robert G. Striegl, D.E. Armstrong. 1990. Carbon dioxide retention and carbon exchange on unsaturated Quaternary sediments. https://doi.org/10.1016/0016-7037(90)90051-l

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