Determination of Geo-dependent Bioavailable 87Sr/86Sr Isotopic Ratios for Archaeological Sites from the Inn Valley (Austria): A Model Calculation

In this chapter, we show how to assess local bioavailable 87Sr/86Sr isotopic ratios of archaeological strata by analysis of water, leached soil samples and vegetation from selected archaeological sites. We present a detailed description and instruction of how to calculate the data. In this pilot study, calculation of cut-off values between local and non-local stable strontium isotopic ratios was performed for five locations in the Austrian Inn Valley. These cut-off values, determined as 87Sr/86Sr(fauna) ± 0.001, agree within acceptable limits with the measured isotopic signature of excavated animal bone material from the chosen archaeological sites. This way, the vertebrate consumer can clearly be classified as a local or non-local individual. Our model calculation, which leads to a reliable geo-dependent bioavailable 87Sr/86Sr isotopic ratio, reveals a high dependence on the isotopic signal from groundwater rather than from soil.