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Main Title Effect of Oxalate on the Dissolution Rates of Oligoclase and Tremolite (Journal Version).
Author Mast, M. A. ; Drever, J. I. ;
CORP Author Wyoming Univ., Laramie. Dept. of Geology and Geophysics.;Corvallis Environmental Research Lab., OR.;National Science Foundation, Washington, DC.
Publisher c1987
Year Published 1987
Report Number EPA-R-813634 ;NSF-EAR83-06567; EPA/600/J-87/462;
Stock Number PB89-134787
Additional Subjects Acid rain ; Air pollution ; Weathering ; Orthoclase ; Silicate minerals ; Amphiboles ; Oxalates ; pH ; Dissolving ; Reprints ; Tremolite
Library Call Number Additional Info Location Last
NTIS  PB89-134787 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 12p
The effect of oxalate, a strong chelator for Al and other cations, on the dissolution rates of oligoclase feldspar and tremolite amphibole was investigated in a flow-through reactor at 22 deg C. Oxalate at concentrations of 0.5 and 1 mM has essentially no effect on the dissolution rate of tremolite, nor on the steady-state rate of release of Si from oligoclase. The fact that oxalate has no effect on dissolution rate suggests that detachment of Si rather than Al or Mg is the rate-limiting step. At pH 4 and 9, oxalate has no effect on the steady-state rate of release of Al, and dissolution is congruent. At pH 5 and 7, oligoclase dissolution is congruent in the presence of oxalate, but in the absence of oxalate Al is preferentially retained in the solid relative to Si. The rate of dissolution of tremolite is independent of pH over the pH range 2-5, and decreases at higher pH. The rate of dissolution of oligoclase was independent of pH over the pH range 4-9. Since the dissolution rate of these minerals is independent of pH and organic ligand concentration, the effect of acid deposition from the atmosphere on the rate of supply of cations from weathering of granitic rocks should be minor. (Copyright (c) Pergamon Journals Ltd., 1987.)