Geochemical and U-Th isotopic insights on uranium enrichment in reservoir sediments
Journal
Journal of Hazardous Materials
Journal Volume
414
Date Issued
2021
Author(s)
Abstract
Uranium (U) geochemistry and its isotopic compositions of reservoir sediments in U mine area were poorly understood. Herein, U and Th isotopic compositions were employed to investigate source apportionment and geochemical behavior of U in 41 reservoir sediments from a U mining area, Guangdong, China. The remarkably high contents of both total U (207.3–1117.7 mg/kg) and acid-leachable U (90.3–638.5 mg/kg) in the sediments exhibit a severe U contamination and mobilization-release risk. The U/Th activity ratios (ARs) indicate that all sediments have been contaminated apparently by U as a result of discharge of U containing wastewater, especially uranium mill tailings (UMT) leachate, while the variations of U/Th ARs are dominated by U geochemical behaviors (mainly redox process and adsorption). The U isotopic compositions (δ238U) showed a large variance through the sediment profile, varying from ? 0.62 to ? 0.04?. The relation between δ238U and acid-leachable U fraction demonstrates that the U isotopic fractionation in sediments can be controlled by bedrock weathering (natural activity), UMT leachate (anthropogenic activity) and subsequent biogeochemical processes. The findings suggest that U-Th isotopes are a powerful tool to better understand U geochemical processes and enrichment mechanism in sediments that were affected by combined sources and driving forces. ? 2021 Elsevier B.V.
Subjects
Binary alloys; Geochemistry; Isotopes; Sediments; Uranium; Anthropogenic activity; Biogeochemical process; Geochemical behaviors; Geochemical process; Isotopic composition; Isotopic fractionations; Source apportionment; Uranium mill tailings; Thorium alloys; ferric oxide; uranium; uranium 234; uranium 238; bedrock; biogeochemistry; discharge; geochemical method; isotopic fractionation; leachate; source apportionment; wastewater treatment; adsorption; Article; China; extended X ray absorption fine structure spectroscopy; geochemical analysis; leaching; mine tailings; mining; oxidation; oxidation reduction reaction; sediment; wastewater; X ray photoemission spectroscopy; China; Guangdong
Type
journal article