rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Roles of naturally occurring bacteria in controlling iodine-129 mobility in subsurface soils
  name:
    name part: Li, Xiuping.
    role:
      role term: creator
  name:
    name part: Brinkmeyer, Robin
    role:
      role term: thesis advisor.
  name:
    name part: Santschi, Peter H.
    role:
      role term: thesis advisor.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2012
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: remote
    extent: 1 online resource.
  abstract: 129I is of major concern because of its biophilic nature, excessive inventory, long half-life (~16 million yrs), and high mobility in the natural environment that depends on its chemical speciation. Iodide (I-) has the highest mobility than iodate (IO3-) and is the predominant species in the terrestrial environment due to prevailing pH and Eh conditions. In order to transform I- to less mobile organo-iodine (OI), strong oxidants are necessary to activate the first electron transfer step from I- to reactive intermediates. The aim of this study was to determine the influence of naturally occurring aerobic bacteria isolated from an 129I contaminated aquifer (F-area of the Savannah River Site, SC) on I- oxidation and OI formation. It was demonstrated that 3 of 136 strains accumulated I- (0.2~2%) in the presence of H2O2, when incubated in the presence of an environmentally relevant concentration of I- (0.1 microM). The accumulation was likely through electrophilic substitution resulting in the iodination of cellular constituents. The results indicated that culturable I--accumulating bacteria are not directly responsible for the high fraction of oxidized iodine species (IO3- and OI, >50% of total I) present in the SRS F-area. Several bacterial strains were found to be capable of stimulating I- oxidation through excretion of oxidants and enzymes. Organic acids in spent liquid medium from 27 of 84 aerobic bacterial cultures enhanced H2O2-dependent I- oxidation 2-10 fold. Organic acids enhanced I- oxidation by (1) lowering the pH of the spent medium and (2) reacting with H2O2 to form peroxy carboxylic acids, which are strong oxidizing agents. In the absence of H2O2, spent medium from 44 of 84 bacteria cultures showed I- oxidizing capacities. One I- oxidizing bacterium was studied to characterize its extracellular I- oxidizing component(s). The I- oxidizing capability from the spent medium was inactive by treatments with heat and H2O2 and absent under anaerobic conditions. Co…
  note: by Hsiu-Ping Li.
  note: "Major Subject: Marine Biology"
  note: Electronic resource.
  note: Doctor of Philosophy Texas A&M University 2012 http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11637
  note: Includes bibliographical references.
  note: Text (Dissertation)
  subject:
    topic: Major Marine Biology
  subject:
    topic: Iodine mobility
  subject:
    topic: bacteria
  subject:
    topic: Savannah River Site
  subject:
    topic: iodide oxidation
  subject:
    topic: iodide accumulation
  subject:
    topic: Iodine-129
  identifier: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11637
  record info:
    record content source: TXA
    record creation date: 121126
    record change date: 20150922145743.0
    record identifier: in00002785517