Effect of oxalate on the dissolution rates of oligoclase and tremolite (journal version)

Technical Report · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6501538

Mast, M A; Drever, J I

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.

• Research Organization: Wyoming Univ., Laramie (USA). Dept. of Geology and Geophysics
• OSTI ID: 6501538
• Report Number(s): PB-89-134787/XAB
• Resource Relation: Other Information: Pub. in Geochimica et Cosmochimica Acta, Vol. 51, 2559-2568(1987)
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ACID RAIN
CHEMICAL REACTIONS
AIR POLLUTION
OXALATES
CHELATING AGENTS
SILICATE MINERALS
WEATHERING
NAPAP
ORTHOCLASE
ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
ATMOSPHERIC PRECIPITATIONS
CARBOXYLIC ACID SALTS
FELDSPARS
MINERALS
OXYGEN COMPOUNDS
POLLUTION
POTASSIUM COMPOUNDS
POTASSIUM SILICATES
RAIN
SILICATES
SILICON COMPOUNDS
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)