Effect of redox potential and pH on arsenic speciation and solubility in a contaminated soil

Journal Article · Thu Aug 01 00:00:00 EDT 1991 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00020a008· OSTI ID:5316682

Masscheleyn, P H; Delaune, R D; Patrick, Jr, W H ^[1]

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1. 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), Vol. 25:8; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ARSENIC
SOLUBILITY
VALENCE
SOILS
PH VALUE
REDOX POTENTIAL
CONTAMINATION
COPRECIPITATION
DISSOLUTION
ENVIRONMENTAL TRANSPORT
EXPERIMENTAL DATA
IRON HYDROXIDES
OXIDATION
X-RAY DIFFRACTION
CHEMICAL REACTIONS
COHERENT SCATTERING
DATA
DIFFRACTION
ELEMENTS
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
IRON COMPOUNDS
MASS TRANSFER
NUMERICAL DATA
OXYGEN COMPOUNDS
PRECIPITATION
SCATTERING
SEMIMETALS
SEPARATION PROCESSES
TRANSITION ELEMENT COMPOUNDS
540220* - Environment
Terrestrial- Chemicals Monitoring & Transport- (1990-)