{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/102885"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/102885","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Uranium isotopes as indicators of uranium immobilization and remobilization in contaminated aquifer settings","abstract":"Tracking U immobilization through U(VI) reduction and mobilization induced by U(IV) oxidation using U concentrations alone is challenging, as groundwater transport, aquifer heterogeneity, and U(VI) adsorption can complicate data interpretation. U isotopes (238U/235U) provide a more direct indicator of these geochemical reactions controlling U mobility. U(VI) reduction induces a strong fractionation of U isotopes, shifting the U isotopes of the remaining U(VI) and producing U(IV) with a distinct isotopic composition. Our published laboratory studies imply that U(VI) adsorption, while impacting U concentrations, has only a minor, consistent effect on U isotopes. Adsorption to various aquifer minerals induces an average isotopic fractionation of -0.15‰ with the adsorbed U(VI) isotopically lighter than coexisting aqueous U(VI). Studies using U isotope data to assess U(VI) reduction and U(IV) oxidation must consider adsorption as a lesser, but significant, isotope fractionation process. Published field studies demonstrate that U(IV) oxidation can be detected via observation of changes in U isotopes. The incorporation of remobilized U(IV) with a high 238U/235U ratio into the aqueous U(VI) pool produces an increase in 238U/235U of aqueous U(VI). However, microbial, geochemical, and hydrologic complexities can complicate the use of 238U/235U in tracking U(IV) oxidation and U(VI) reduction. Through inclusion of 238U/235U into a multicomponent reactive transport modeling framework, we track U removal during both natural and biostimulated U(VI) reduction and U remobilization during U(IV) oxidation to develop 238U/235U as a simple, reliable tool for analyzing U geochemical behavior.","abstract_html":"Tracking U immobilization through U(VI) reduction and mobilization induced by U(IV) oxidation using U concentrations alone is challenging, as groundwater transport, aquifer heterogeneity, and U(VI) adsorption can complicate data interpretation. U isotopes (238U/235U) provide a more direct indicator of these geochemical reactions controlling U mobility. U(VI) reduction induces a strong fractionation of U isotopes, shifting the U isotopes of the remaining U(VI) and producing U(IV) with a distinct isotopic composition. Our published laboratory studies imply that U(VI) adsorption, while impacting U concentrations, has only a minor, consistent effect on U isotopes. Adsorption to various aquifer minerals induces an average isotopic fractionation of -0.15‰ with the adsorbed U(VI) isotopically lighter than coexisting aqueous U(VI). Studies using U isotope data to assess U(VI) reduction and U(IV) oxidation must consider adsorption as a lesser, but significant, isotope fractionation process. Published field studies demonstrate that U(IV) oxidation can be detected via observation of changes in U isotopes. The incorporation of remobilized U(IV) with a high 238U/235U ratio into the aqueous U(VI) pool produces an increase in 238U/235U of aqueous U(VI). However, microbial, geochemical, and hydrologic complexities can complicate the use of 238U/235U in tracking U(IV) oxidation and U(VI) reduction. Through inclusion of 238U/235U into a multicomponent reactive transport modeling framework, we track U removal during both natural and biostimulated U(VI) reduction and U remobilization during U(IV) oxidation to develop 238U/235U as a simple, reliable tool for analyzing U geochemical behavior.","abstract_has_math":false,"creators":["Jemison, Noah"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["Johnson, Thomas M.","Druhan, Jennifer L","Lundstrom, Craig C.","Sanford, Robert A."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-02-08T18:39:38Z","date_published":"2019-02-08T18:39:38Z","updated_at":"2026-07-22T22:24:42Z","subjects":["238U/235U, U(VI) reduction, U(IV) oxidation"],"languages":["en"],"rights":["Copyright 2018 Noah Jemison"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/102885","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","Lundstrom, Craig C.","Sanford, Robert A."]},{"key":"dc:creator","label":"Author","values":["Jemison, Noah"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-02-08T18:39:38Z","2021-02-09T10:15:38Z","2018-08-27","2018-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"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":["238U/235U, U(VI) reduction, U(IV) oxidation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2018 Noah Jemison"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/102885"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Tracking U immobilization through U(VI) reduction and mobilization induced by U(IV) oxidation using U concentrations alone is challenging, as groundwater transport, aquifer heterogeneity, and U(VI) adsorption can complicate data interpretation. U isotopes (238U/235U) provide a more direct indicator of these geochemical reactions controlling U mobility. U(VI) reduction induces a strong fractionation of U isotopes, shifting the U isotopes of the remaining U(VI) and producing U(IV) with a distinct isotopic composition. Our published laboratory studies imply that U(VI) adsorption, while impacting U concentrations, has only a minor, consistent effect on U isotopes. Adsorption to various aquifer minerals induces an average isotopic fractionation of -0.15‰ with the adsorbed U(VI) isotopically lighter than coexisting aqueous U(VI). Studies using U isotope data to assess U(VI) reduction and U(IV) oxidation must consider adsorption as a lesser, but significant, isotope fractionation process. Published field studies demonstrate that U(IV) oxidation can be detected via observation of changes in U isotopes. The incorporation of remobilized U(IV) with a high 238U/235U ratio into the aqueous U(VI) pool produces an increase in 238U/235U of aqueous U(VI). However, microbial, geochemical, and hydrologic complexities can complicate the use of 238U/235U in tracking U(IV) oxidation and U(VI) reduction. Through inclusion of 238U/235U into a multicomponent reactive transport modeling framework, we track U removal during both natural and biostimulated U(VI) reduction and U remobilization during U(IV) oxidation to develop 238U/235U as a simple, reliable tool for analyzing U geochemical behavior.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-12-01","The student, Noah Jemison, accepted the attached license on 2018-08-24 at 16:28.","The student, Noah Jemison, submitted this Dissertation for approval on 2018-08-24 at 16:38.","This Dissertation was approved for publication on 2018-08-27 at 14:58.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12982 on 2019-02-08 at 11:37:35","Made available in DSpace on 2019-02-08T18:39:38Z (GMT). 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U isotopes (238U/235U) provide a more direct indicator of these geochemical reactions controlling U mobility. U(VI) reduction induces a strong fractionation of U isotopes, shifting the U isotopes of the remaining U(VI) and producing U(IV) with a distinct isotopic composition. Our published laboratory studies imply that U(VI) adsorption, while impacting U concentrations, has only a minor, consistent effect on U isotopes. Adsorption to various aquifer minerals induces an average isotopic fractionation of -0.15‰ with the adsorbed U(VI) isotopically lighter than coexisting aqueous U(VI). Studies using U isotope data to assess U(VI) reduction and U(IV) oxidation must consider adsorption as a lesser, but significant, isotope fractionation process. Published field studies demonstrate that U(IV) oxidation can be detected via observation of changes in U isotopes. The incorporation of remobilized U(IV) with a high 238U/235U ratio into the aqueous U(VI) pool produces an increase in 238U/235U of aqueous U(VI). However, microbial, geochemical, and hydrologic complexities can complicate the use of 238U/235U in tracking U(IV) oxidation and U(VI) reduction. Through inclusion of 238U/235U into a multicomponent reactive transport modeling framework, we track U removal during both natural and biostimulated U(VI) reduction and U remobilization during U(IV) oxidation to develop 238U/235U as a simple, reliable tool for analyzing U geochemical behavior.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-12-01","The student, Noah Jemison, accepted the attached license on 2018-08-24 at 16:28.","The student, Noah Jemison, submitted this Dissertation for approval on 2018-08-24 at 16:38.","This Dissertation was approved for publication on 2018-08-27 at 14:58.","DSpace SAF Submission Ingestion Package generated from Vireo submission #12982 on 2019-02-08 at 11:37:35","Made available in DSpace on 2019-02-08T18:39:38Z (GMT). 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