The strontium isotope ratio ⁸⁷Sr/⁸⁶Sr in archaeological organic matter conserved in acidic anaerobic environments is hard to interpret

The strontium isotope ratio ⁸⁷Sr/⁸⁶Sr is used to determine the provenance of archaeological organic matter. However, for organic matter in an acidic environment such as peat bogs and Bronze Age burial mounds, the interpretation of the ratio is not straightforward. The acidic environment in peat bogs and Bronze Age burial mounds dissolves parts of the organic matter so that the chemically bounded strontium in hair, nails, bones and teeth is released into the aqueous environment. This dissipation of strontium can change the local strontium isotope ratio and affect the possibility of a precise determination of the provenance of the organic matter. The article provides a chemical and physicochemical analysis of the acidic effect on the isotope ratio in organic matter, and shows how to detect whether the diagenesis might have changed the original strontium isotope ratio.