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MINERAL DISSOLUTION RATES IN PLOT-SCALE FIELD AND LABORATORY EXPERIMENTS
Citation:
Swoboda-Colberg, N. AND J. Drever. MINERAL DISSOLUTION RATES IN PLOT-SCALE FIELD AND LABORATORY EXPERIMENTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/458 (NTIS PB94112976), 1993.
Description:
Mineral dissolution rates were measured in 6 small (2 m2) plots on a spodosal in eastern Maine. he plots were irrigated with HCI at pH 2, 2.5, and 3: soil solutions were collected by tension lysimeters at 25 and 50 cm depths. he composition of the soil solutions, together with the grain-size distribution mineralogy of the soil, were used to calculate mineral dissolution rates. he dissolution rate of the 75-150 gm size fraction of soil from the site was measured in flow-through reactors at the same pH as the soil solutions. he use of small plots and "untreated" minerals from the same plots eliminates many of the uncertainties in previous field-laboratory comparisons. issolution rates observed in the field, normalized on the basis of geometrical mineral surface area, were smaller than laboratory rates by a factor of about 200. he discrepancy can be explained by a number of factors. he major reason is probably imperfect contact between soil minerals and percolating solution. acropore flow or limited exchange between water in micropores and the bulk soil solution could reduce the mineral surface area participating in the dissolution process. art of the discrepancy might be explained by the dissolution rate not scaling with geometrical surface area.
