Comments on responses to our paper “Assessment of radionuclide retardation: Uses and abuses of natural analogues” (original) (raw)

1993, Journal of Contaminant Hydrology

The tone of our paper may be harsh, but we feel that it is important that a growing trend to over-interpret limited field measurements be nipped in the bud. This is particularly critical when such measurements could be used incorrectly in the analysis of different options for the disposal of radioactive (or any other toxic) waste. An essential point is that there appears to be no disagreement about our definition of sorption or the importance of distinguishing between sorption and precipitation in transport models. The four replies to our paper (McKinley and Alexander, 1993 in this issue) basically either make the case that the ratios measured were, in fact, rigorous "Kd's" of the type we define or, alternatively, that the ratios measured were never intended to be used in transport calculations. Jackson certainly has the strongest case for the former, as the 9°Sr which he studied comes from a well-defined source and hence has no "matrix" component. We still feel that discounting possible precipitation on the basis of calculated saturation indices (Jackson and Inch, 1983) for pure minerals is dangerous due to uncertainties in the data bases used (not very critical for this particular case) and the critical r61e played by coprecipitation in controlling the solubility of trace elements at concentrations well below those expected on the basis of "pure phases". Coprecipitation can be especially important when significant concentrations of Fe-oxyhydroxides are available (e.g., Bruno et al., 1991), which is the case for the aquifer examined in this study. Jackson's own data (Jackson and Inch, 1989), indeed, show that early estimates of "-~ 80% of 9°Sr being exchangeable with SrC12 have been revised to 35% and he quotes Killey and Munch (1987) stating that "over 50% (of 90 Sr) was released by a treatment that partially dissolves the oxide coatings". Given this key r61e of Fe-AI-Mn-oxides, it is strange that Jackson comments that the

Sign up for access to the world's latest research.

checkGet notified about relevant papers

checkSave papers to use in your research

checkJoin the discussion with peers

checkTrack your impact