کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4546745 1627064 2012 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Diffusive release of uranium from contaminated sediments into capillary fringe pore water
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Diffusive release of uranium from contaminated sediments into capillary fringe pore water
چکیده انگلیسی

Despite remediation efforts at the former nuclear weapons facility, leaching of uranium (U) from contaminated sediments to the ground water persists at the Hanford site 300 Area. Flooding of contaminated capillary fringe sediments due to seasonal changes in the Columbia River stage has been identified as a source for U supply to ground water. We investigated U release from Hanford capillary fringe sediments by packing sediments into reservoirs of centrifugal filter devices and saturating them with Columbia River water for 3 to 84 days at varying solution-to-solid ratios. After specified times, samples were centrifuged. Within the first three days, there was an initial rapid release of 6–9% of total U, independent of the solution-to-solid ratio. After 14 days of reaction, however, the experiments with the narrowest solution-to-solid ratios showed a decline in dissolved U concentrations. The removal of U from the solution phase was accompanied by removal of Ca and HCO3−. Geochemical modeling indicated that calcite could precipitate in the narrowest solution-to-solid ratio experiment. After the rapid initial release in the first three days for the wide solution-to-solid ratio experiments, there was sustained release of U into the pore water. This sustained release of U from the sediments had diffusion-limited kinetics.


► Sediments have reacted with river water up to 84 days at varying solution-to-solid ratio.
► Initial release of 6–9% of total U, independent of the solution-to-solid ratio
► Narrowest ratios showed a decline in dissolved U concentrations.
► The removal of U from the solution phase was accompanied by removal of Ca and HCO3.
► Wide ratio tests displayed diffusion-limited kinetics of U release from sediment.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Contaminant Hydrology - Volumes 140–141, October 2012, Pages 164–172
نویسندگان
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