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Leaching characteristics of a high-calcium fly ash as a function of pH: A potential source of selenium toxicity

January 1, 1988

Using a modified extraction procedure, the effect of pH on the leaching of selected elements from Ca-rich (Type C) power plant fly ash was studied. Continuous additions of acetic acid were used to maintain pH values of fly ash slurries at 4.0, 6.0 and 8.0 for 24 h and an additional set was leached at its natural pH (average 11.8) value. Analyses for Se, As, Ca, Cd, Cr, Fe, Na and Pb showed that the highest concentrations occur in the leachate at pH 4.0 and decline with increasing pH. Concentrations of Cr and Fe increased slightly between neutral and high pH. Arsenic, Cd, Cr, Pb and Se concentrations exceeded the Environmental Protection Agency's toxicity criteria at pH 4.0. Selenium was above its toxicity level at pH values near 7 but the other elements were below their respective toxicity levels near neutral pH. Because recent studies show adverse effects of Se on aquatic life at far lower concentrations than the current Environmental Protection Agency's standard, high-Ca, power plant fly ashes represent a potentially hazardous pollutant to surface and subsurface waters.

Publication Year 1988
Title Leaching characteristics of a high-calcium fly ash as a function of pH: A potential source of selenium toxicity
DOI 10.1016/0883-2927(88)90092-3
Authors D. A. Grisafe, E.E. Angino, S. M. Smith
Publication Type Article
Publication Subtype Journal Article
Series Title Applied Geochemistry
Index ID 70013749
Record Source USGS Publications Warehouse