Effects of gamma-sterilization on the physico-chemical properties of natural sediments

Journal Article · Mon Jun 30 04:00:00 EDT 2008 · Chemical Geology, 251(1-4):1-7

DOI:https://doi.org/10.1016/j.chemgeo.2008.01.003· OSTI ID:935598

Bank, Tracy L; Kukkadapu, Ravi K; Madden, Andrew S; Baldwin, M E; Jardine, Philip M

A series of experiments were completed to determine the effects of soil sterilization on various soil chemical properties including U(VI) sorption, soil pH, natural organic matter (NOM), cation exchange capacity (CEC), and iron oxidation state. Soils under investigation were a saprolitic sequence of interbedded weathered shale and limestone collected from the Oak Ridge Reservation (ORR). Sediments were sterilized by either steam sterilization at 121oC or by γ-irradiation using a cobalt-60 source. Subsamples of sediments were pretreated with dithionate-citrate-bicarbonate (DCB) and/or H2O2 to remove reducible Fe(III) oxides and NOM. Results from aerobic U(VI) sorption experiments indicated that γ-sterilized sediments sorbed more U(VI) compared to non-sterile sediments. Results from sorption experiments completed using DCB and H2O2-treated samples indicated that the iron oxide and NOM fractions of the sediment accounted for the majority of U(VI) sorption and that γ-irradiation of these phases resulted in increased sorption of U(VI). Mössbauer spectra of γ-sterilized sedimentsdisplayed a decrease in the amount of ferric iron associated with goethite and a small increase in the amount of reduced iron in silicate minerals compared to spectra from non-sterile samples. Our results suggest that sterilization by γ-irradiation induced iron reduction that may have increased sorption of U(VI) on these sediments.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 935598
• Report Number(s): PNNL-SA-54410; 16690; KP1504020
• Journal Information: Chemical Geology, 251(1-4):1-7, Journal Name: Chemical Geology, 251(1-4):1-7 Journal Issue: 1-4 Vol. 251; ISSN CHGEAD; ISSN 0009-2541
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CATIONS
CHEMICAL PROPERTIES
COBALT 60
Environmental Molecular Sciences Laboratory
GOETHITE
ION EXCHANGE
IRON
IRON OXIDES
LIMESTONE
ORGANIC MATTER
OXIDES
SEDIMENTS
SHALES
SILICATE MINERALS
SOILS
SORPTION
SPECTRA
STEAM
STERILIZATION
VALENCE