sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: II. In vitro simulation of kinetic isotope effects

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90283-4· OSTI ID:7000662

McConnaughey, T ^[1]

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1. Univ. of Washington, Seattle (USA)

Biological carbonates are built largely from CO{sub 2}, which diffuses across the skeletogenic membrane and reacts to form HCO{sub 3}{sup {minus}}. Kinetic discrimination against the heavy isotopes {sup 18}O and {sup 13}C during CO{sub 2} hydration and hydroxylation apparently causes most of the isotopic disequilibrium observed in biological carbonates. These kinetic isotope effects are expressed when the extracytosolic calcifying solution is thin and alkaline, and HCO{sub 3}{sup {minus}} precipitates fairly rapidly as CaCO{sub 3}. In vitro simulation of the calcifying environment produced heavy isotope depletions qualitatively similar to, but somewhat more extreme than, those seen in biological carbonates. Isotopic equilibration during biological calcification occurs through CO{sub 2} exchange across the calcifying membrane and by admixture ambient waters (containing HCO{sub 3}{sup {minus}}) into the calcifying fluids. Both mechanisms tend to produce linear correlations between skeletal {delta}{sup 13}C and {delta}{sup 18}O.

• OSTI ID: 7000662
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 53:1; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
59 BASIC BIOLOGICAL SCIENCES
ARAGONITE
BIOCHEMICAL REACTION KINETICS
PRECIPITATION
CORALS
EXOSKELETON
MINERAL CYCLING
BIOGEOCHEMISTRY
CARBON 13
CARBON DIOXIDE
CHEMICAL COMPOSITION
ECUADOR
EQUILIBRIUM
HYDRATION
HYDROXYLATION
ISOTOPE RATIO
OXYGEN 18
PARTITION
REEFS
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BODY
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
CHEMISTRY
CNIDARIA
COELENTERATA
DEVELOPING COUNTRIES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOCHEMISTRY
GEOLOGIC STRUCTURES
INVERTEBRATES
ISOTOPES
KINETICS
LATIN AMERICA
LIGHT NUCLEI
MINERALS
NUCLEI
ORGANS
OXIDES
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
REACTION KINETICS
SEPARATION PROCESSES
SKELETON
SOLVATION
SOUTH AMERICA
STABLE ISOTOPES
580000* - Geosciences
550500 - Metabolism