Iron dynamics during injection of dissolved organic carbon into a sandy aquifer

Conference · Tue Jan 01 04:00:00 EST 1991

OSTI ID:6254866

Liang, Liyuan; McCarthy, J F ^[1]; Williams, T M ^[2]

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1. Oak Ridge National Lab., TN (USA)
2. Clemson Univ., Georgetown, SC (USA). Belle W. Baruch Forest Science Inst.

The dynamics of dissolved, colloidal, and solid-phase iron were examined during a forced-gradient field experiment in Georgetown, South Carolina, in the summer of 1990. The experiment involved injection of 80,000 L of oxygenated water containing high levels of dissolved organic carbon (66 mg/L DOC) into a sandy aquifer. Iron dynamics were followed for 2 weeks in three saturated horizons at sampling wells located 1.5 (A wells) and 3 m (B wells) from the injection well. The initial oxidation/reduction potential of the aquifer favored Fe(II) in the iron-rich groundwater. As oxygen-rich water was introduced into the groundwater, the redox potential was expected to increase. The impacts of the changing redox potential on iron dynamics were hypothesized to be as follows: (1) Fe(II) may decrease and Fe(III) may increase due to oxidation, but otherwise Fe(II) may be mobile and conservative. (2) Fe(III) is mostly in the ferric oxide/hydroxide colloidal fraction, that is, the ferric fraction may be found predominantly in sizes >{sup {approximately}}1 nm(or >3000 mol wt), and the transport of colloidal iron oxide may be limited. (3) Ferric oxide/hydroxide colloids may have positive or near-zero surface charge in the pH range of the groundwater (6.0-7.2). (4) The turbidity of groundwater may increase as a result of the formation of iron colloids. During the course of injection, dissolved oxygen (DO), pH, iron concentration, DOC concentration, and turbidity were measured. Samples were also collected for microelectrophoretic mobility measurement (Coulter model: Delsa 440), particle-size analysis (Coulter model: N4MD, based on photon correlation spectrometry (PCS)) and scanning electron microscopic examination (ISI-40). The results from the two sampling wells are summarized briefly. 4 refs., 3 figs., 1 tab.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6254866
• Report Number(s): CONF-910473-2; ON: DE91007183
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
AQUIFERS
CHALCOGENIDES
CHEMICAL EFFLUENTS
CHEMISTRY
COLLOIDS
COMPLEXES
DATA
DIFFUSION
DISPERSIONS
DISSOLVED GASES
ECOLOGICAL CONCENTRATION
ELECTRON MICROSCOPY
ELEMENTS
EXPERIMENTAL DATA
FEDERAL REGION IV
FLUIDS
GASES
GROUND WATER
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
INJECTION WELLS
IRON
IRON COMPLEXES
IRON COMPOUNDS
IRON HYDROXIDES
IRON OXIDES
METALS
MICROSCOPY
NORTH AMERICA
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PHASE STUDIES
REDOX POTENTIAL
SCANNING ELECTRON MICROSCOPY
SOLUTES
SOUTH CAROLINA
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TURBIDITY
USA
WATER
WATER CHEMISTRY
WELLS