Potential and Limitations of Strontium Isotopic Fingerprinting in Wood

Abstract

While the isotopic composition of strontium (⁸⁷Sr/⁸⁶Sr) is frequently used in archeological and environmental provenience studies, it remains unclear how bioavailable Sr in organic matter and the food chain reflects bedrock sources. Here, we present Sr isotopic measurements of 24 soil and 120 wood samples from four central European forests with variable basement geology. While ⁸⁷Sr/⁸⁶Sr values in bedrock (0.7035–0.7441) and soil (0.7043–0.7552) have a considerable span, wood ⁸⁷Sr/⁸⁶Sr values across sites have a much smaller range (0.7041–0.7245), which is closer to the large-scale atmospheric Sr signature in precipitation (0.7118). Comparable ⁸⁷Sr/⁸⁶Sr ratios for different tree species, cambial ages and root systems suggest that bioavailable Sr in wood is little affected by biotic factors. Given the strength of the atmospheric Sr signal we identify, archeological, environmental and forensic fingerprinting should consider high-resolution spatial isoscape modeling, for which this study provides a baseline for central Europe.