Uranium and Vanadium Concentrations as a Trace Element Method for Identifying Diagenetically Altered Bone in the Inorganic Phase

Archaeologists have generally avoided analyzing inorganic isotopes in bone because of its high porosity, large crystalline lattice spacing, and small crystallite size, making it particularly susceptible to diagenetic alteration. Because the inorganic isotopes are left unstudied, we lose a significant portion of information pertaining to an individual’s life history, such as migration, health, and ranging behavior. Tooth enamel, which does not have the same susceptibility to diagenesis as bone, can be used to extract this information but this means that taxa lacking teeth, such as birds, some species of fish, and some reptiles, are excluded. Here, we present a method that can be used to identify diagenetic alternation in bone. This is done by focusing on abnormal concentrations of vanadium and uranium. Neither element is readily bio-precipitated into hydroxyapatite due to ionic radius, vibrational frequency, atomic mass, and ionic charge. This makes them an ideal marker for diagenetically altered bone. Vanadium occurs in very low concentrations in modern bone, while archaeological bone shows clear evidence of normal, non-diagenetically altered values alongside high concentrations of vanadium in diagenetically altered bone. Uranium also is a measure of diagenetic alteration, as modern bone has concentrations below detectable limits (0.017 ppb), while some archaeological bone contains uranium above detectable limits. The biogeochemistry of these elements in soil and bone are discussed with implications for enamel studies.