{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/124565"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/124565","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Isotopes of selenium as redox tracers of geochemical processes influencing the export and behavior of selenium contamination in coal mine watersheds","abstract":"Selenium is a redox-active element that is necessary for life in small quantities but causes toxic effects for wildlife above 5 μg/L in water and for humans above 50 μg/L in drinking water. Se contamination is released by oxidative weathering of Se-bearing shales, and this contamination is often associated with mining activity. Selenium is most mobile and toxic in its oxidized Se(VI) form, less mobile as Se(IV), and immobile in the Se(0) or Se(-II) forms. Se isotope ratios have been developed to measure the presence and extent of geochemical processes affecting the mobility and environmental impact of Se. Se isotope systematics are well defined through laboratory experiments but have seldom been applied to real environments. The leftover material from coal mines within the Appalachian region is constructed into valley fills along mountain slopes, which produce Se-laden effluents exceeding EPA regulations. The redox conditions within these watersheds are relatively unknown, and the behavior of Se is not well studied. Water samples collected from 3 valley fills and their respective watersheds were analyzed for Se concentration, Se speciation, and 82Se/76Se isotope ratios. A leaching experiment on shale to determine the Se(VI) isotopic composition before the Se(VI) undergoes redox reactions yielded a δ82/76Se = -0.46‰ for Se(VI). The δ82/76Se values of surface water samples observed at each site for Se(VI) were; Mary’s Fork (2.56 – 4.54‰), 4-Mile Site (3.38 – 3.86‰), and the T&M Site (3.53 – 4.35‰). The isotopically heavy values of Se(VI) suggest that reduction of Se(VI) occurs within the fills. A trend of increasingly heavy Se(VI) values further downstream is hypothesized to occur due to Se(VI) reduction in the hyporheic zone. The groundwater and isotope data suggest that the effluents leaving the toe are a mix of runoff from oxic and suboxic/anoxic portions of the fill, highlighting the heterogeneous structure and varying redox conditions within valley fills.","abstract_html":"Selenium is a redox-active element that is necessary for life in small quantities but causes toxic effects for wildlife above 5 μg/L in water and for humans above 50 μg/L in drinking water. Se contamination is released by oxidative weathering of Se-bearing shales, and this contamination is often associated with mining activity. Selenium is most mobile and toxic in its oxidized Se(VI) form, less mobile as Se(IV), and immobile in the Se(0) or Se(-II) forms. Se isotope ratios have been developed to measure the presence and extent of geochemical processes affecting the mobility and environmental impact of Se. Se isotope systematics are well defined through laboratory experiments but have seldom been applied to real environments. The leftover material from coal mines within the Appalachian region is constructed into valley fills along mountain slopes, which produce Se-laden effluents exceeding EPA regulations. The redox conditions within these watersheds are relatively unknown, and the behavior of Se is not well studied. Water samples collected from 3 valley fills and their respective watersheds were analyzed for Se concentration, Se speciation, and 82Se/76Se isotope ratios. A leaching experiment on shale to determine the Se(VI) isotopic composition before the Se(VI) undergoes redox reactions yielded a δ82/76Se = -0.46‰ for Se(VI). The δ82/76Se values of surface water samples observed at each site for Se(VI) were; Mary’s Fork (2.56 – 4.54‰), 4-Mile Site (3.38 – 3.86‰), and the T&M Site (3.53 – 4.35‰). The isotopically heavy values of Se(VI) suggest that reduction of Se(VI) occurs within the fills. A trend of increasingly heavy Se(VI) values further downstream is hypothesized to occur due to Se(VI) reduction in the hyporheic zone. The groundwater and isotope data suggest that the effluents leaving the toe are a mix of runoff from oxic and suboxic/anoxic portions of the fill, highlighting the heterogeneous structure and varying redox conditions within valley fills.","abstract_has_math":false,"creators":["Stiegman, Matthew S"],"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"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-05","date_published":"2024-05","updated_at":"2026-07-22T22:25:02Z","subjects":["Isotope Geochemistry","Selenium"],"languages":["eng","en"],"rights":["Copyright 2024 Matthew Stiegman"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/124565","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Johnson, Thomas M"]},{"key":"dc:creator","label":"Author","values":["Stiegman, Matthew S"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2024-05","2024-04-30"]},{"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":["Isotope Geochemistry","Selenium"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng","en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2024 Matthew Stiegman"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/124565"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Selenium is a redox-active element that is necessary for life in small quantities but causes toxic effects for wildlife above 5 μg/L in water and for humans above 50 μg/L in drinking water. Se contamination is released by oxidative weathering of Se-bearing shales, and this contamination is often associated with mining activity. Selenium is most mobile and toxic in its oxidized Se(VI) form, less mobile as Se(IV), and immobile in the Se(0) or Se(-II) forms. Se isotope ratios have been developed to measure the presence and extent of geochemical processes affecting the mobility and environmental impact of Se. Se isotope systematics are well defined through laboratory experiments but have seldom been applied to real environments. The leftover material from coal mines within the Appalachian region is constructed into valley fills along mountain slopes, which produce Se-laden effluents exceeding EPA regulations. The redox conditions within these watersheds are relatively unknown, and the behavior of Se is not well studied. Water samples collected from 3 valley fills and their respective watersheds were analyzed for Se concentration, Se speciation, and 82Se/76Se isotope ratios. A leaching experiment on shale to determine the Se(VI) isotopic composition before the Se(VI) undergoes redox reactions yielded a δ82/76Se = -0.46‰ for Se(VI). The δ82/76Se values of surface water samples observed at each site for Se(VI) were; Mary’s Fork (2.56 – 4.54‰), 4-Mile Site (3.38 – 3.86‰), and the T&M Site (3.53 – 4.35‰). The isotopically heavy values of Se(VI) suggest that reduction of Se(VI) occurs within the fills. A trend of increasingly heavy Se(VI) values further downstream is hypothesized to occur due to Se(VI) reduction in the hyporheic zone. The groundwater and isotope data suggest that the effluents leaving the toe are a mix of runoff from oxic and suboxic/anoxic portions of the fill, highlighting the heterogeneous structure and varying redox conditions within valley fills.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","The student, Matthew Stiegman, accepted the attached license on 2024-04-23 at 13:38.","The student, Matthew Stiegman, submitted this Thesis for approval on 2024-04-23 at 13:55.","This Thesis was approved for publication on 2024-04-30 at 16:38.","DSpace SAF Submission Ingestion Package generated from Vireo submission #20581 on 2024-09-16 at 00:44:26"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Isotopes of selenium as redox tracers of geochemical processes influencing the export and behavior of selenium contamination in coal mine watersheds"]}]}],"canonical_facts":{"dc:contributor":["Johnson, Thomas M"],"dc:creator":["Stiegman, Matthew S"],"dc:date":["2024-05","2024-04-30"],"dc:description":["Selenium is a redox-active element that is necessary for life in small quantities but causes toxic effects for wildlife above 5 μg/L in water and for humans above 50 μg/L in drinking water. Se contamination is released by oxidative weathering of Se-bearing shales, and this contamination is often associated with mining activity. Selenium is most mobile and toxic in its oxidized Se(VI) form, less mobile as Se(IV), and immobile in the Se(0) or Se(-II) forms. Se isotope ratios have been developed to measure the presence and extent of geochemical processes affecting the mobility and environmental impact of Se. Se isotope systematics are well defined through laboratory experiments but have seldom been applied to real environments. The leftover material from coal mines within the Appalachian region is constructed into valley fills along mountain slopes, which produce Se-laden effluents exceeding EPA regulations. The redox conditions within these watersheds are relatively unknown, and the behavior of Se is not well studied. Water samples collected from 3 valley fills and their respective watersheds were analyzed for Se concentration, Se speciation, and 82Se/76Se isotope ratios. A leaching experiment on shale to determine the Se(VI) isotopic composition before the Se(VI) undergoes redox reactions yielded a δ82/76Se = -0.46‰ for Se(VI). The δ82/76Se values of surface water samples observed at each site for Se(VI) were; Mary’s Fork (2.56 – 4.54‰), 4-Mile Site (3.38 – 3.86‰), and the T&M Site (3.53 – 4.35‰). The isotopically heavy values of Se(VI) suggest that reduction of Se(VI) occurs within the fills. A trend of increasingly heavy Se(VI) values further downstream is hypothesized to occur due to Se(VI) reduction in the hyporheic zone. The groundwater and isotope data suggest that the effluents leaving the toe are a mix of runoff from oxic and suboxic/anoxic portions of the fill, highlighting the heterogeneous structure and varying redox conditions within valley fills.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","The student, Matthew Stiegman, accepted the attached license on 2024-04-23 at 13:38.","The student, Matthew Stiegman, submitted this Thesis for approval on 2024-04-23 at 13:55.","This Thesis was approved for publication on 2024-04-30 at 16:38.","DSpace SAF Submission Ingestion Package generated from Vireo submission #20581 on 2024-09-16 at 00:44:26"],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/124565"],"dc:language":["eng","en"],"dc:rights":["Copyright 2024 Matthew Stiegman"],"dc:subject":["Isotope Geochemistry","Selenium"],"dc:title":["Isotopes of selenium as redox tracers of geochemical processes influencing the export and behavior of selenium contamination in coal mine watersheds"],"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":"2026-07-22T22:25:02Z"}