Mapping bone microstructure trace element composition: Sr, Ba, Cu, and Pb in an early modern Danish skeleton

Objectives: A Geographical Information System (GIS) approach enhances the acquisition, management, and analysis of trace element data from cortical bone. A high-resolution spatial dimension expands the research potential of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) data from cortical bone cross-sections. The chemical characterization of hundreds of osteons, notably sequences of superimposed osteons, permits more exacting studies of individual life histories than is possible with analyses of bulk bone samples. Methods: A GIS procedure was used to estimate Sr, Ba, Pb, and Cu concentrations, originally generated through LA-ICP-MS, for bone microstructural features, notably fragmentary and intact osteons, in a human femoral cross-section. The skeleton is from Ribe, Denmark, and dates to the early modern period. Results: Postmortem chemical alteration was limited to the bone's outer and inner margins. Two dietary indicators, Sr and Ba, and two socioeconomic indicators, Pb and Cu, measured for individual osteons were correlated with one another. Osteon sequences indicate concentrations of all four elements increased late in life for this individual. Conclusions: The application of GIS procedures expedites fine-grained analyses of variation in the distribution of trace elements in bone microstructure identifiable in cortical bone cross-sections. It provides an efficient means of extracting the most information possible from LA-ICP-MS data about the lives of people in the past. Combining the two procedures makes it easier to track exposure to elements such as Pb across the part of an individual's life represented by osteon sequences.