title: Calcined bone provides a reliable substrate for strontium isotope ratios as shown by an enrichment experiment.
abstract: BACKGROUND
  Strontium isotopes ((87) Sr/(86) Sr) are used in archaeological and forensic science as markers of residence or mobility because they reflect the local geological substrate. Currently, tooth enamel is considered to be the most reliable tissue, but it rarely survives heating so that in cremations only calcined bone fragments survive. We set out to test the proposition that calcined bone might prove resistant to diagenesis, given its relatively high crystallinity, as the ability to measure in vivo (87) Sr/(86) Sr from calcined bone would greatly extend application to places and periods in which cremation was the dominant mortuary practice, or where unburned bone and enamel do not survive.
  
  
  METHODS
  Tooth enamel and calcined bone samples were exposed to a (87) Sr-spiked solution for up to 1 year. Samples were removed after various intervals, and attempts were made to remove the contamination using acetic acid washes and ultrasonication. (87) Sr/(86) Sr was measured before and after pre-treatment on a Nu Plasma multi-collector induced coupled plasma mass spectrometer using NBS987 as a standard.
  
  
  RESULTS
  The strontium isotopic ratios of all samples immersed in the spiked solution were strongly modified showing that significant amounts of strontium had been adsorbed or incorporated. After pre-treatment the enamel samples still contained significant amounts of (87) Sr-enriched contamination while the calcined bone fragments did not.
  
  
  CONCLUSIONS
  The results of the artificial enrichment experiment demonstrate that calcined bone is more resistant to post-mortem exchange than tooth enamel, and that in vivo strontium isotopic ratios are retained in calcined bone.
authors.affiliation: Research Laboratory for Archaeology and the History of Art, University of Oxford, Dyson Perrins Building, South Parks Rd, Oxford, OX1 3QY, UK.
authors.forename: Christophe
authors.initials: C
authors.lastname: Snoeck
authors.forename: Julia
authors.initials: J
authors.lastname: Lee-Thorp
authors.forename: Rick
authors.initials: R
authors.lastname: Schulting
authors.forename: Jeroen
authors.initials: J
authors.lastname: de Jong
authors.forename: Wendy
authors.initials: W
authors.lastname: Debouge
authors.forename: Nadine
authors.initials: N
authors.lastname: Mattielli
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000737:chemistry*; D002417:Cattle; D055700:Cremation; D003743:Dental Enamel / Q000737:chemistry; D006736:Horses; D013058:Mass Spectrometry; D013325:Strontium Isotopes / Q000032:analysis* / Q000737:chemistry
chemical_list: D013325:Strontium Isotopes