کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1877638 1042221 2014 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Assessment of a sequential phase extraction procedure for uranium-series isotope analysis of soils and sediments
ترجمه فارسی عنوان
بررسی یک روش استخراج فاز متوالی برای تجزیه ایزوتوپ سری اورانیم خاک و رسوبات
موضوعات مرتبط
مهندسی و علوم پایه فیزیک و نجوم تشعشع
چکیده انگلیسی


• We tested a sequential extraction procedure for U-series isotope analysis on powdered rock standards (TML-3 and BCR-2) and a soil sample.
• The leaching procedure does not impart any artifactual isotope fractionation to the sample.
• Considerable U and Th are removed from the samples.
• Mineralogy of the sample is unaffected by the procedure.
• Redistribution of isotopes occurred during leaching.

The study of uranium-series (U-series) isotopes in soil and sediment materials has been proposed to quantify rates and timescales of soil production and sediment transport. Previous works have studied bulk soil or sediment material, which is a complex assemblage of primary and secondary minerals and organic compounds. However, the approach relies on the fractionation between U-series isotopes in primary minerals since they were liberated from the parent rock via weathering. In addition, secondary minerals and organic compounds have their own isotopic compositions such that the composition of the bulk material may not reflect that of primary minerals. Hence, there is a need for a sample preparation procedure that allows the isolation of primary minerals in soil or fluvial sediment samples. In this study, a sequential extraction procedure to separate primary minerals from soils and sediments was assessed. The procedure was applied to standard rock sample powders (TML-3 and BCR-2) to test whether it introduced any artefactual radioactive disequilibrium. A new step was introduced to remove the clay-sized fraction (<2 µm). Significant amounts (5–14%) of U and Th were removed from the rock standards during the procedure. No significant alteration in (234U/238U) and (230Th/238U) activity ratios of the rock standards occurred during the procedure. Aliquots of soil sample were subjected to the sequential extraction process to test how each step modifies the uranium-series activity ratios and mineralogy. Although no secondary minerals were detected in the unleached soil aliquots, the sequential leaching process removed up to 17% of U and Th and modified their activity ratios by up to 3%. The modification of the activity ratios poses a demand for careful means to avoid redistribution of isotopes back to the residual phase during phase extraction.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Radiation and Isotopes - Volume 83, Part A, January 2014, Pages 47–55
نویسندگان
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