If the mixture contains multiple fractions of young water, the resulting age is regarded as a mean age of the young fraction(s) in the mixture.
Additionally, location of the mid-1960s bomb peak provides information on recharge rate (Schlosser and others, 1988, 1989; Solomon and Sudicky, 1991; Solomon and others, 1992, 1993; Ekwurzel and others, 1994). Mixing, if it occurs, may not be readily apparent if the concentration of a particular constituent (such as dissolved Cl He, there will almost always be compositional gradients, especially when ground water is sampled from relatively large intervals in aquifers. In any mixture containing a fraction of post-bomb water and a fraction of pre-bomb water, the detectable He age will be intermediate to the ages of the post-bomb fractions. There is usually insufficient data for resolving mixtures of more than one post-bomb water in ground-water mixtures, and consequently, the reported ages (both He- and CFC-based ages) should be regarded as mixed ages for the young fraction(s) in each sample. See for example Plummer and others (1998a, 1998b, 2000). B., and Krause, D., Jr., 1980, Isotopic fractionation of helium during solution: A probe for the liquid state: J.