Iodine and 129I were extracted from three sediment cores collected in Western Lake Ontario which has received atmospheric deposition and watershed discharge from a defunct nuclear fuel reprocessing facility. Since carbon tetrachloride which is traditionally used to extract iodine into an aqueous phase has significant environmental, health, and regulatory problems associated with its use, we performed a series of experiments on 14 solvents and solvent mixtures to find an alternative solvent extraction system for iodine. Chlorobenzene and a 50:50 mixture of carbon tetrachloride and dichloromethane were as efficient in extracting iodine as pure CCl4 and form suitable alternatives for this solvent which is being phased out. 129I concentrations in the sediments range from (95-951,338) x 103 atoms/g, while 129I /127I ratios range from (1.23) x 10-12 to (3.58) x 10-9. 129I and iodine are immobilized in the surficial layers of sediment with pronounced decreases in concentration with increasing depth. The mobility of iodine and 129I in the sediment column was found to be highly redox sensitive, with high fluxes from sediment to porewater under anoxic conditions at depth and retention under oxic conditions in surface layers. The retention at the surface is probably driven by the association of iodine species with organic matter and/or Fe and Al oxides. An inventory of 129I in the top 13 cm of the sediment column, the water column, and surface soil from the watershed indicates that the water and sediments of Lake Ontario retain significantly less 129I than the drainage basin soil, and thus do not form the primary long-term sink for 129I released from regional reprocessing. Wide-scale atmospheric dispersion of reprocessing releases is thus implied.
See more of Poster Session II
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)