Environmental sampling to capture bioavailable strontium isotope distributions on Corsica

Strontium isotopes (⁸⁷Sr/⁸⁶Sr) are a powerful geochemical tracer to reconstruct mobility and provenance of bioarcheological and palaeoecological materials. This study presents the first bioavailable Sr isoscape for Corsica based on environmental samples and compares these new results to a global predictive model. The environmental samples consist of plant (n = 245) and ammonium nitrate leached soil (n = 81) samples from 125 sampling sites across the island, creating a comprehensive bioavailable strontium baseline for Corsica. Observed spatial trends in ⁸⁷Sr/⁸⁶Sr are related to the geological age and lithology, with an overall range of 0.7075–0.7169. Soil leachate samples exhibit significantly lower ⁸⁷Sr/⁸⁶Sr values than their paired plant counterparts. The influence of sea spray on terrestrial samples is observed up to 700 m inland around the island. An isoscape was created using Ordinary Kriging within geological units to capture both the influence of geological and environmental conditions on the biologically available ⁸⁷Sr/⁸⁶Sr of Corsica. Compared to a global bioavailable strontium isoscape, the baseline created here shows large differences, especially for samples collected on older lithologies of Variscan Corsica (Carboniferous granite and monzogranite, and Permian rhyolitoid). While the global isoscape predicts the overall spatial patterning of ⁸⁷Sr/⁸⁶Sr values, there is a continued need for extensive environmental sampling to capture the finer scale ⁸⁷Sr/⁸⁶Sr values variability, especially in geologically complex areas. This bioavailable Sr isotope baseline for Corsica allows for the interpretation of mobility from archaeological and palaeoecological samples on the island.