On the Incorrect Derivation and Use of In-situ Retardation Factors from Natural Isotope Profiles

The characterization of the retardation of radionuclides during their transport by deep groundwaters is complex, time-consum-ing and, in many cases, inherently limited by technical problems. The stated goal of many natural analogue studies is thus the direct quantification of solute retardation in-situ in relevant geological environments. This paper reviews the claims for a methodology for determining in-situ retardation factors from a mathematical deconvolution of multiple radioisotope measure-ments of natural decay series elements. It is concluded that the assumptions involved in development of the mathematical ap-proach are geochemically inconsistent and inapplicable to most geological systems of interest. Misapplications of this model are identified and the dangers of accepting its nonsensical output are discussed.