INVESTIGADORES
VALENZUELA Luciano Oscar
congresos y reuniones científicas
Título:
COMBINING STRONTIUM AND OXYGEN ISOTOPE RATIOS OF HAIR FOR HUMAN PROVENANCING
Autor/es:
TIPPLE, BRETT; VALENZUELA, LUCIANO O; CHESSON, LESLEY A; BOWEN, GABRIEL; EHLERINGER, JAMES R
Reunión:
Encuentro; GSA's 125th Anniversary Annual Meeting & Exposition; 2013
Institución organizadora:
The Geological Society of America
Resumen:
Understanding an individual?s travel-history can be an important piece
of information in a forensic investigation. The analysis of stable
oxygen (O) isotopes of human hair has assisted in the reconstruction of
the geographic-movement histories of individuals in criminal
investigations. While oxygen isotope values (δ18O) of human
hair provide geographic origin information, the estimated regions can be
spatially broad. Strontium (Sr) isotope ratios (87Sr/86Sr) of human hair can provide a complementary isotopic approach to measurement of 18O in hair for human provenancing as 87Sr/86Sr ratios record independent geographic information and thus further constrain the estimated regions predicted by δ18O
values. To understand the linkages between the Sr and O isotope systems
in keratinous tissues and an individual?s environment, human hair and
tap waters were collected throughout the Salt Lake Valley of Utah and
the 87Sr/86Sr ratios and δ18O values were measured on paired samples. We found that different communities were provided municipal water with distinct 87Sr/86Sr ratios. Hairs with higher 87Sr/86Sr ratios were from individuals that resided in neighborhoods that had higher tap water 87Sr/86Sr ratios. Furthermore, we observed the majority of paired tap water and hair 87Sr/86Sr
ratios had a 1:1 relationship, indicating little to no fractionation
between Sr isotope ratios in water and hair. We found the δ18O
values of Salt Lake City water and hair samples had an average value of
-16.2 ? and 9.8 ?, respectively. We used the hair model of Ehleringer
et al. (2008) to predict tap water δ18O values of an individual?s drinking water source and observed that the predicted tap water δ18O values agreed with the measured δ18O
values of tap water available in the community. Our findings indicated
that different municipalities within the Salt Lake Valley used different
combinations of water resources and these combinations of water
resources provided a unique isotopic marker for a municipality. In turn,
these community-specific isotopic signals were reflected in the isotope
ratios of the hair of individuals that resided within that particular
neighborhood. We propose that the paired analyses of both O and Sr
isotope ratios in hair may allow for greater refinement in
reconstructing the travel-movement history of an individual.