Partitioning of iodine-129 in the environment

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Authors:Alvarado Quiro, Nicolas G.; Clark, Ian D.; Kotzer, T. G.; Milton, G. M.
Author Affiliations:Primary:
University of Ottawa, Department of Earth Sciences, Ottawa, ON, Canada
Atomic Energy of Canada, Canada
Volume Title:Geological Society of America, 1998 annual meeting
Source:Abstracts with Programs - Geological Society of America, 30(7), p.361-362; Geological Society of America, 1998 annual meeting, Toronto, ON, Canada, Oct. 26-29, 1998. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592
Publication Date:1998
Note:In English
Summary:Solid, low-level radioactive wastes from industrial, academic and medical applications have been stored in trenches at the Chalk River Laboratories of Atomic Energy of Canada Ltd. The trenches overlie an unconsolidated groundwater flow system in sandy, glacial tills and permeable very-fine to fine-grained sands overlying bedrock. The sandy aquifer system drains into a swamp comprised of approximately 3 m of sphagnum peat. Hydrogeologically, yearly precipitation available for recharge (approx. 340 mm/a) percolates into the underlying aquifer which has generated a contaminant plume, having chemical characteristics of a dilute, sanitary landfill leachate containing C-14 (DOC, DIC), tritium (HTO) and levels of I-129 which are elevated above present-day precipitation levels of approximately 10E7 atoms I-129/litre water. Measurements consisting of total I, I-129, tritium, C-14 and C-13/C-12 ratios in groundwater and geologic and biogenic materials have been initiated to examine the partitioning of I-127/I-129 amongst the various reservoirs in this system and its controlling factors. To date, groundwaters from several boreholes with multi-level piezometers transecting the flow system have been sampled, as well as cores from sands and peats and some local vegetation to characterize the general hydrochemistry of the system to obtain information on the distribution of I-127 and I-129. The total I concentration [ng/ml] and I-129 [atoms/litre] inside the plume at the recharge site and discharge site were 6.88 ng/ml (16E10 atoms/litre) and 26.00 ng/ml (8E10 atoms/litre), respectively. These values are similar to fissiogenic I-129 concentrations measured in saline groundwaters from uriferous granites and high grade U-ore deposits. Positive correlations between stable iodine (and I-129) and C-14, tritium and DOC are evident. Combustion analyses of soil cores taken near the recharge (sandy soils) and discharge (peats) sites showed a total I concentration inside the plume of 4.8 ng/ml and 350 ng/ml, respectively, suggesting partitioning into these organic-rich peats. Samples of cedar trees, previously exposed and/or planted in the swamp, are being analyzed in an effort to distinguish between atmospheric adsorption and root uptake of I-129. The factors controlling the partitioning of stable- and radio-iodine will be discussed on the basis of the data.
Subjects:Adsorption; Aquifers; Bedrock; C-13/C-12; C-14; Carbon; Clastic sediments; Controls; Cores; Discharge; Ground water; Halogens; Hydrogen; Hydrology; I-129; Iodine; Isotope ratios; Isotopes; Leachate; Low-level waste; Organic carbon; Partitioning; Permeability; Radioactive isotopes; Radioactive waste; Rainfall; Recharge; Sampling; Sediments; Soils; Solutes; Stable isotopes; Till; Tritium; Vegetation; Waste disposal; Canada; Chalk River Ontario; Eastern Canada; Ontario; Renfrew County Ontario; I-129/I-127
Coordinates:N460100 N460100 W0772800 W0772800
Record ID:1999024665
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
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