Mobilization of natural colloids from an iron oxide-coated sand aquifer: Effect of pH and ionic strength

Environmental Science & Technology
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Abstract

Field and laboratory column experiments were performed to assess the effect of elevated pH and reduced ionic strength on the mobilization of natural colloids in a ferric oxyhydroxide-coated aquifer sediment. The field experiments were conducted as natural gradient injections of groundwater amended by sodium hydroxide additions. The laboratory experiments were conducted in columns of undisturbed, oriented sediments and disturbed, disoriented sediments. In the field, the breakthrough of released colloids coincided with the pH pulse breakthrough and lagged the bromide tracer breakthrough. The breakthrough behavior suggested that the progress of the elevated pH front controlled the transport of the mobilized colloids. In the laboratory, about twice as much colloid release occurred in the disturbed sediments as in the undisturbed sediments. The field and laboratory experiments both showed that the total mass of colloid release increased with increasing pH until the concurrent increase in ionic strength limited release. A decrease in ionic strength did not mobilize significant amounts of colloids in the field. The amount of colloids released normalized to the mass of the sediments was similar for the field and the undisturbed laboratory experiments.

Publication type Article
Publication Subtype Journal Article
Title Mobilization of natural colloids from an iron oxide-coated sand aquifer: Effect of pH and ionic strength
Series title Environmental Science & Technology
DOI 10.1021/es0109141
Volume 36
Issue 3
Year Published 2002
Language English
Publisher American Chemical Society
Contributing office(s) Toxic Substances Hydrology Program
Description 9 p.
First page 314
Last page 322
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