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20150922145743.0 |
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m fo d |
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cr unu|||||||| |
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121126s2012 txu obm 000 0 eng d |
| 035 |
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|a (OCoLC)ocn819341323
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| 035 |
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|a (TxCM)http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11637
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|a TXA
|c TXA
|d UtOrBLW
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| 049 |
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|a TXAM
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| 099 |
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|a 2012
|a Dissertation
|a 1969.1/ETD-TAMU-2012-08-11637
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| 100 |
1 |
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|a Li, Xiuping.
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|a Roles of naturally occurring bacteria in controlling iodine-129 mobility in subsurface soils /
|c by Hsiu-Ping Li.
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| 264 |
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1 |
|a [College Station, Tex.] :
|b [Texas A&M University],
|c [2012]
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| 300 |
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|a 1 online resource.
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| 336 |
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|a text
|b txt
|2 rdacontent
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| 337 |
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|a computer
|b c
|2 rdamedia
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| 338 |
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|a online resource
|b cr
|2 rdacarrier
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| 500 |
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|a "Major Subject: Marine Biology"
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| 588 |
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|a Description from author supplied metadata (automated record created 2012-10-22 13:24:58).
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| 502 |
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|b Doctor of Philosophy
|c Texas A&M University
|d 2012
|o http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11637
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|a Includes bibliographical references.
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|a Text (Dissertation)
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3 |
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|a 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. Conversely, NADH, NADPH and FMN additions stimulated I- oxidation in the spend medium. These results indicate an oxidase(s) catalyzed I- oxidation. Understanding the bacterial activities involved with I- oxidation and OI formation is expected to help reduce 129I mobility in water-soil systems.
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| 500 |
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|a Electronic resource.
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| 650 |
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4 |
|a Major Marine Biology.
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|a Iodine mobility
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| 653 |
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|a bacteria
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| 653 |
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|a Savannah River Site
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| 653 |
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|a iodide oxidation
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| 653 |
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|a iodide accumulation
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| 653 |
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|a Iodine-129
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| 700 |
1 |
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|a Brinkmeyer, Robin,
|e thesis advisor.
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| 700 |
1 |
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|a Santschi, Peter H.,
|e thesis advisor.
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| 856 |
4 |
0 |
|u http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11637
|z Link to OAK Trust copy
|t 0
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| 948 |
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|a cataloged
|b h
|c 2012/11/26
|d c
|e ceaton
|f 1:29:48 pm
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| 994 |
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|a C0
|b TXA
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| 999 |
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|a MARS
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| 999 |
f |
f |
|s 9b713783-efcc-3fbd-b08f-0f244983ae0b
|i 3bdc80f9-b5fb-3585-87f3-8bc9ff225bc2
|t 0
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| 952 |
f |
f |
|a Texas A&M University
|b College Station
|c Electronic Resources
|d Available Online
|t 0
|e 2012 Dissertation 1969.1/ETD-TAMU-2012-08-11637
|h Other scheme
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| 998 |
f |
f |
|a 2012 Dissertation 1969.1/ETD-TAMU-2012-08-11637
|t 0
|l Available Online
|