U.S. flag

An official website of the United States government, Department of Justice.

Reconstruction of Travel History Using Coupled delta18O and 87Sr/86Sr Measurements of Hair

NCJ Number
Date Published
March 2017
7 pages
Thuan H. Chau, Brett J. Tipple, Lihai Hu, Diego P. Fernandez, Thure E. Cerling, James R. Ehleringer, Lesley A. Chesson
This study tested the hypothesis that oxygen isotope ratios (delta18O values) of hair largely reflect features of regional hydrology, and strontium isotope ratios (87Sr/86Sr) are thought to reflect bedrock geology; and a combination of both isotope signatures may provide greater capacity for determining provenance and reconstructing travel history of an organism.
This study compared the O-Sr isotope profiles of hair from domestic horses with known residency histories. Tail hairs were collected from a pair of horses pastured together for a period of 16 months, one of which lived in a different location for the 8 months prior. Hair samples were washed with solvents to remove external contaminants prior to sequential sampling for delta18O and 87Sr/86Sr analysis via TC/EA-IRMS and MC-ICP-MS, respectively. Hair digests were concentrated and analyzed employing low-flow natural aspiration to measure 87Sr/86Sr. The study found that tail hair from the control and transported horses had mean δ18O values of 11.25 ± 1.62 ‰ and 10.96 ± 1.53 ‰, and mean 87Sr/86Sr of 0.7101 ± 0.0006 and 0.7109 ± 0.0020, respectively. The delta18O and 87Sr/86Sr profiles for the control and transported horses were indistinguishable when they were pastured together. The 87Sr/86Sr profiles were significantly different during the period that the horses were living apart, and the delta18O values were indistinguishable during that period. By comparing the O-Sr isotope profiles of a control and transported horse, researchers investigated isotopic signal(s) potentially useful for reconstructing travel histories via high-resolution sequential sampling along single strands of tail hair. Improved analytical capabilities allowed for extremely low Sr abundance samples to be analyzed for 87Sr/86Sr and proved capable of resolving a horse's movement between distinct regions. (Publisher abstract modified)
Date Created: November 5, 2018