Effect of redox potential and pH on arsenic speciation and solubility in a contaminated soil
- Louisiana State Univ., Baton Rouge (United States)
The influence of redox potential and pH on arsenic speciation and solubility was studied in a contaminated soil. Alterations in the oxidation state of arsenic, and influenced by redox potential and pH, greatly affected its solubility in soil. At higher soil redox levels (500-200 mV), arsenic solubility was low and the major part (65-98%) of the arsenic in solution was present as As(V). An alkaline pH, or the reduction of As(V) to As(III), released substantial proportions of arsenic into solution. Under moderately reduced soil conditions (0-100 mV), arsenic solubility was controlled by the dissolution of iron oxyhydroxides. Arsenic was coprecipitated (as As(V)) with iron oxyhydroxides and released upon their solubilization. Upon reduction to {minus}200 mV, the soluble arsenic content increased 13-fold as compared to 500 mV. The observed slow kinetics of the As(V)-As(III) transformation and the high concentrations of Mn present indicate that, under reduced soil conditions, arsenic solubility could be controlled by a Mn{sub 3}(AsO{sub 4}){sub 2} phase.
- OSTI ID:
- 5316682
- Journal Information:
- Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 25:8; ISSN ESTHA; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ARSENIC
CHEMICAL REACTIONS
COHERENT SCATTERING
CONTAMINATION
COPRECIPITATION
DATA
DIFFRACTION
DISSOLUTION
ELEMENTS
ENVIRONMENTAL TRANSPORT
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
IRON COMPOUNDS
IRON HYDROXIDES
MASS TRANSFER
NUMERICAL DATA
OXIDATION
OXYGEN COMPOUNDS
PH VALUE
PRECIPITATION
REDOX POTENTIAL
SCATTERING
SEMIMETALS
SEPARATION PROCESSES
SOILS
SOLUBILITY
TRANSITION ELEMENT COMPOUNDS
VALENCE
X-RAY DIFFRACTION