Strontium isotopes in human mobility research: BASr proxies in an anthropologically modified landscape

Abstract

Establishing a local ⁸⁷Sr/⁸⁶Sr range is a vital requirement for identifying non-locals in bioarchaeological mobility studies using strontium isotopes. In regions heavily influenced by modern human activities, however, the sampling of suitable materials that can be used to decipher the bioavailable ⁸⁷Sr/⁸⁶Sr range might be challenging. Here, we collected a wide range of samples representing different reference types of materials from the Nové Mlýny reservoirs area of South Moravia, Czech Republic, and discuss their suitability in human mobility research studies. This included 15 surface water samples, 15 homogenised plant samples, 12 tooth enamel and 1 dentine sample, 1 bone sample from archaeofauna, 6 snail shells and 6 human bones. The measured ⁸⁷Sr/⁸⁶Sr ratios revealed the major influence of strontium of non-local origin, carried by the Jihlava river, on the local waterscape. This influence is further enhanced by the changes to the waterscape during the 20th century and carried over to other sample libraries. The presented results demonstrate that special care is needed when selecting reference samples, to allow for a proper understanding of the prevailing conditions in the biologically available strontium (BASr) and to ensure a reliable BASr range estimation.