Variation in Isotopic Abundances of Uranium Isotopes in Soi

[Craig D Brown <CBROWN@envc.sandia.gov>]

Can anyone provide a reference regarding studies of natural
abundaces of uranium isotopes in soil.  It's easy enough to
find what they are expected to be (99.2739% for U-238,
0.7204% for U-235, and 0.0057% for U-234), what I would
like to know is how far "natural" distributions may deviate
from these percentages.  I am specifically concerned with
near-surface soils (I have reviewed studies regarding
variations in deep aquifers).  Please respond to the e-mail
address below.

Craig D. Brown
cbrown@envc.sandia.gov