Distribution, speciation, and transformation of chromium in contaminated soils and aquifer sediments

Technical Report · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5245838

Puls, R W; Paul, C J; Clark, D A

Knowledge of the chemical speciation and distribution of chromium at hazardous waste sites is essential for adequate site characterization and risk assessment. Contaminant speciation, whether dissolved or in association with solid surfaces, will affect the toxicity and mobility of most contaminants in subsurface systems. This is particularly true of chromium, which exists as Cr(VI) and Cr(III) species in subsurface systems. The chemical speciation and distribution of chromium on unsaturated contaminated soils, and saturated aquifer sediments was analyzed in the vicinity of a chrome plating operation. Sequential extractions and selective ion exchange experiments were performed to infer mineral fractions responsible for retention of the chromium on the solid phase, and the chemical form (speciation) of the retained chromium. Reduction of Cr(VI) to Cr(III) and subsequent precipitation as (Fe,Cr) (OH)3 is proposed as the primary attenuation mechanism in the unsaturated soils immediately beneath the shop. Chromium reduction in the saturated aquifer sediments is significantly less effective in attenuation of the delineated Cr(VI) ground-water plume. Scanning electron microscopy with energy dispersive X-ray analyses, and cursory modelling efforts with CHROMAT were also used to complement wet chemical methods in assessments of chromium transport and transformation.

• Research Organization: Environmental Protection Agency, Ada, OK (United States). Robert S. Kerr Environmental Research Lab.
• OSTI ID: 5245838
• Report Number(s): PB-92-179092/XAB; EPA--600/A-92/084
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
AQUIFERS
CHEMICAL ANALYSIS
CHEMISTRY
CHROMIUM
CONTAMINATION
DEPOSITION
ELECTRODEPOSITION
ELECTROLYSIS
ELECTRON MICROSCOPY
ELECTROPLATING
ELEMENTS
ENVIRONMENTAL TRANSPORT
EXTRACTION
INTERFACES
ION EXCHANGE
LAND POLLUTION
LYSIS
MANAGEMENT
MASS TRANSFER
MATHEMATICAL MODELS
METALS
MICROSCOPY
NONDESTRUCTIVE ANALYSIS
PLATING
POLLUTION
SCANNING ELECTRON MICROSCOPY
SEDIMENT-WATER INTERFACES
SEDIMENTS
SEPARATION PROCESSES
SOIL CHEMISTRY
SOILS
SURFACE COATING
TRANSITION ELEMENTS
WASTE DISPOSAL
WASTE MANAGEMENT
WATER POLLUTION
X-RAY EMISSION ANALYSIS