Reactive Solute Transport in an Acidic Stream: Experimental pH Increase and Simulation of Controls on pH, Aluminum, and Iron

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• 作者：Robert E. Broshears ; Robert L. Runkel ; Briant A. Kimball ; Diane M. McKnight ; and Kenneth E. Bencala
• 刊名：Environmental Science & Technology
• 出版年：1996
• 出版时间：October 1996
• 年：1996
• 卷：30
• 期：10
• 页码：3016 - 3024
• 全文大小：449K
• 年卷期：v.30,no.10(October 1996)
• ISSN：1520-5851

文摘

Solute transport simulations quantitatively constrainedhydrologic and geochemical hypotheses about fieldobservations of a pH modification in an acid minedrainage stream. Carbonate chemistry, the formationof solid phases, and buffering interactions with thestream bed were important factors in explaining thebehavior of pH, aluminum, and iron. The precipitationof microcrystalline gibbsite accounted for the behaviorof aluminum; precipitation of Fe(OH)₃ explainedthegeneral pattern of iron solubility. The dynamicexperiment revealed limitations on assumptions that reactions were controlled only by equilibrium chemistry.Temporal variation in relative rates ofphotoreductionand oxidation influenced iron behavior. Kineticlimitations on ferrous iron oxidation and hydrous oxideprecipitation and the effects of these limitations onfieldfiltration were evident. Kinetic restraints alsocharacterized interaction between the water columnand the stream bed, including sorption and desorptionof protons from iron oxides at the sediment-waterinterface and post-injection dissolution of theprecipitated aluminum solid phase.