{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/90833"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/90833","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Investigating uranium mobility using groundwater 238U/235U data and a reactive transport model","abstract":"\"In order to better understand chemical reactions affecting the subsurface transport of the widespread contaminant uranium (U), we present a numerical reactive transport model which explicitly incorporates variations in the 238U/235U isotope ratio. Bioremediation, the microbial reductive immobilization of aqueous U(VI) to solid U(IV), has been proposed as a U remediation technique. Both laboratory and field experiments have demonstrated that microbial reduction of U(VI) alters 238U/235U, producing a 238U-enriched solid U(IV) product. Other major U reactive transport processes do not fractionate isotopes significantly. This suggests the potential to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U as a compliment to the information gained through U concentration measurements. A recent study of a U bioremediation experiment at a contaminated DOE site in Rifle, Colorado, applied Rayleigh distillation models to quantify U stable isotope fractionation observed during biostimulation via acetate amendment. These simplified models have known inaccuracies and do not incorporate the complex hydrologic and geochemical aspects of the site. To more accurately interpret these measured U isotope ratios, we present a multi-component reactive transport model capable of reproducing observed trends in geochemistry and 238U/235U ratios from the field experiment. Model results suggest that the rate-limited transport properties of U in the Rifle aquifer are governed by the presence of low-permeability regions in the modeling domain and that these zones are responsible for the suggested \"\"memory\"\" effect observed in previous U isotope studies at this site. Accurate modeling of observed U isotope ratios is crucial to their use as a method of tracking bioremediation, and this study serves to advance the quantitative application of isotope systems in reactive transport.\"","abstract_html":""In order to better understand chemical reactions affecting the subsurface transport of the widespread contaminant uranium (U), we present a numerical reactive transport model which explicitly incorporates variations in the 238U/235U isotope ratio. Bioremediation, the microbial reductive immobilization of aqueous U(VI) to solid U(IV), has been proposed as a U remediation technique. Both laboratory and field experiments have demonstrated that microbial reduction of U(VI) alters 238U/235U, producing a 238U-enriched solid U(IV) product. Other major U reactive transport processes do not fractionate isotopes significantly. This suggests the potential to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U as a compliment to the information gained through U concentration measurements. A recent study of a U bioremediation experiment at a contaminated DOE site in Rifle, Colorado, applied Rayleigh distillation models to quantify U stable isotope fractionation observed during biostimulation via acetate amendment. These simplified models have known inaccuracies and do not incorporate the complex hydrologic and geochemical aspects of the site. To more accurately interpret these measured U isotope ratios, we present a multi-component reactive transport model capable of reproducing observed trends in geochemistry and 238U/235U ratios from the field experiment. Model results suggest that the rate-limited transport properties of U in the Rifle aquifer are governed by the presence of low-permeability regions in the modeling domain and that these zones are responsible for the suggested ""memory"" effect observed in previous U isotope studies at this site. Accurate modeling of observed U isotope ratios is crucial to their use as a method of tracking bioremediation, and this study serves to advance the quantitative application of isotope systems in reactive transport."","abstract_has_math":false,"creators":["Bizjack, Matthew Thomas"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["Johnson, Thomas M.","Druhan, Jennifer L"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-07-07T20:35:17Z","date_published":"2016-07-07T20:35:17Z","updated_at":"2026-07-22T22:26:34Z","subjects":["uranium","bioremediation","reactive transport","stable isotopes","CrunchTope","rate-limited desorption"],"languages":["en"],"rights":["Copyright 2016 Matthew Bizjack"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/90833","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Johnson, Thomas M.","Druhan, Jennifer L"]},{"key":"dc:creator","label":"Author","values":["Bizjack, Matthew Thomas"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016-07-07T20:35:17Z","2018-07-08T09:15:33Z","2016-04-26","2016-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["uranium","bioremediation","reactive transport","stable isotopes","CrunchTope","rate-limited desorption"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2016 Matthew Bizjack"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/90833"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["\"In order to better understand chemical reactions affecting the subsurface transport of the widespread contaminant uranium (U), we present a numerical reactive transport model which explicitly incorporates variations in the 238U/235U isotope ratio. Bioremediation, the microbial reductive immobilization of aqueous U(VI) to solid U(IV), has been proposed as a U remediation technique. Both laboratory and field experiments have demonstrated that microbial reduction of U(VI) alters 238U/235U, producing a 238U-enriched solid U(IV) product. Other major U reactive transport processes do not fractionate isotopes significantly. This suggests the potential to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U as a compliment to the information gained through U concentration measurements. A recent study of a U bioremediation experiment at a contaminated DOE site in Rifle, Colorado, applied Rayleigh distillation models to quantify U stable isotope fractionation observed during biostimulation via acetate amendment. These simplified models have known inaccuracies and do not incorporate the complex hydrologic and geochemical aspects of the site. To more accurately interpret these measured U isotope ratios, we present a multi-component reactive transport model capable of reproducing observed trends in geochemistry and 238U/235U ratios from the field experiment. Model results suggest that the rate-limited transport properties of U in the Rifle aquifer are governed by the presence of low-permeability regions in the modeling domain and that these zones are responsible for the suggested \"\"memory\"\" effect observed in previous U isotope studies at this site. Accurate modeling of observed U isotope ratios is crucial to their use as a method of tracking bioremediation, and this study serves to advance the quantitative application of isotope systems in reactive transport.\"","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-05-01","The student, Matthew Bizjack, accepted the attached license on 2016-04-26 at 10:43.","The student, Matthew Bizjack, submitted this Thesis for approval on 2016-04-26 at 10:54.","This Thesis was approved for publication on 2016-04-26 at 12:24.","DSpace SAF Submission Ingestion Package generated from Vireo submission #9499 on 2016-07-07 at 13:50:55","Made available in DSpace on 2016-07-07T20:35:17Z (GMT). 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Bioremediation, the microbial reductive immobilization of aqueous U(VI) to solid U(IV), has been proposed as a U remediation technique. Both laboratory and field experiments have demonstrated that microbial reduction of U(VI) alters 238U/235U, producing a 238U-enriched solid U(IV) product. Other major U reactive transport processes do not fractionate isotopes significantly. This suggests the potential to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U as a compliment to the information gained through U concentration measurements. A recent study of a U bioremediation experiment at a contaminated DOE site in Rifle, Colorado, applied Rayleigh distillation models to quantify U stable isotope fractionation observed during biostimulation via acetate amendment. These simplified models have known inaccuracies and do not incorporate the complex hydrologic and geochemical aspects of the site. To more accurately interpret these measured U isotope ratios, we present a multi-component reactive transport model capable of reproducing observed trends in geochemistry and 238U/235U ratios from the field experiment. Model results suggest that the rate-limited transport properties of U in the Rifle aquifer are governed by the presence of low-permeability regions in the modeling domain and that these zones are responsible for the suggested \"\"memory\"\" effect observed in previous U isotope studies at this site. Accurate modeling of observed U isotope ratios is crucial to their use as a method of tracking bioremediation, and this study serves to advance the quantitative application of isotope systems in reactive transport.\"","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-05-01","The student, Matthew Bizjack, accepted the attached license on 2016-04-26 at 10:43.","The student, Matthew Bizjack, submitted this Thesis for approval on 2016-04-26 at 10:54.","This Thesis was approved for publication on 2016-04-26 at 12:24.","DSpace SAF Submission Ingestion Package generated from Vireo submission #9499 on 2016-07-07 at 13:50:55","Made available in DSpace on 2016-07-07T20:35:17Z (GMT). No. of bitstreams: 2 BIZJACK-THESIS-2016.pdf: 2787474 bytes, checksum: 8eb8fc42b9bb014d88571def3d5bdfae (MD5) LICENSE.txt: 4212 bytes, checksum: 985af1c00209bbbfe2eea88cb0791ad3 (MD5) Previous issue date: 2016-04-26","Embargo set by: Seth Robbins for item 93186 Lift date: 2018-07-07T20:35:34Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 93186 on 2018-07-08T09:15:33Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/90833"],"dc:language":["en"],"dc:rights":["Copyright 2016 Matthew Bizjack"],"dc:subject":["uranium","bioremediation","reactive transport","stable isotopes","CrunchTope","rate-limited desorption"],"dc:title":["Investigating uranium mobility using groundwater 238U/235U data and a reactive transport model"],"dc:type":["text"],"thesis:degree_discipline":["Geology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:34Z"}