Uranium speciation in a San Joaquin Valley (SJV), CA evaporation pond sediment

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:560060

Duff, M C; Tait, C D; Morris, D E ^[1]; Amrhein, C ^[2]

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1. Los Alamos National Lab., NM (United States)
2. Univ. of California, Riverside, CA (United States); and others

Evaporation ponds in the SJV, CA used for the containment of irrigation drainage waters, contain elevated levels of U. The ponds support algae which upon evaporation, become incorporated in sediments as layers of organic matter (OM). The OM facilitates reducing conditions in the sediment. However, our past studies show sediment U exists as primarily the oxidized form, U(VI)--regardless of redox status. Our research was conducted with this pond sediment to further characterize U speciation and the influence of pond algae on sediment U redox chemistry. The research involved techniques such as X-ray absorption spectroscopy, basic and time-resolved luminescence spectrometry in addition to wet chemistry methods. Uranium(VI) reduction in the sediment was observed in the presence of alfalfa (as a microbial energy source) under anaerobic conditions and reduction was not promoted by native pond algae under oxidizing conditions. Sediment U(VI) most likely exists as two groups of luminescent species: U(VI)-oxides/U(VI)-hydroxides and U(VI)-organics.

• OSTI ID: 560060
• Report Number(s): CONF-970443--
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
ABSORPTION SPECTROSCOPY
ALFALFA
ALGAE
CONTAINMENT
EVAPORATION
LUMINESCENCE
RADIOACTIVE WASTE DISPOSAL
REDUCTION
SEDIMENTS
URANIUM