TY - JOUR
T1 - Herbivore tooth oxygen isotope compositions
T2 - Effects of diet and physiology
AU - Kohn, Matthew J.
AU - Schoeninger, Margaret J.
AU - Valley, John W.
PY - 1996/10
Y1 - 1996/10
N2 - The applicability of rapid and precise laser probe analysis of tooth enamel for δ18O has been verified, and the method has been applied to different modern herbivores in East Africa. Sampling and pretreatment procedures involve initial bleaching and grinding of enamel to <75 μm, and elimination of adsorbed water and organic compounds with BrF5. Typical analytical reproducibilities for 0.5-2 mg samples are ±0.08‰ (±1σ). Chemical and spectroscopic characterization of pretreated but unanalyzed samples show no alteration compared to fresh enamel. Solid reaction products are nearly pure CaF2 with little evidence for residual O2. Because laser probe fluorination extracts oxygen from all sites in the apatite structure (phosphate, structural carbonate, and hydroxyl), only unaltered tooth enamel (>95% apatite) can be analyzed reliably. Different East African herbivores exhibit previously unsuspected compositional differences. Average enamel δ18O values (V-SMOW) are approximately: 25‰ (goat), 27‰ (oryx), 28‰ (dikdik and zebra), 29‰ (topi), 30‰ (gerenuk), and 32‰ (gazelle). These compositions differ from generalized theoretical models, but are broadly consistent with expected isotope effects associated with differences in how much each animal (a) drinks, (b) eats C3 vs. C4 plants, and (c) pants vs. sweats. Consideration of diet, water turnover, and animal physiology will allow the most accurate interpretation of ancient teeth and targeting of environmentally-sensitive animals in paleoclimate studies.
AB - The applicability of rapid and precise laser probe analysis of tooth enamel for δ18O has been verified, and the method has been applied to different modern herbivores in East Africa. Sampling and pretreatment procedures involve initial bleaching and grinding of enamel to <75 μm, and elimination of adsorbed water and organic compounds with BrF5. Typical analytical reproducibilities for 0.5-2 mg samples are ±0.08‰ (±1σ). Chemical and spectroscopic characterization of pretreated but unanalyzed samples show no alteration compared to fresh enamel. Solid reaction products are nearly pure CaF2 with little evidence for residual O2. Because laser probe fluorination extracts oxygen from all sites in the apatite structure (phosphate, structural carbonate, and hydroxyl), only unaltered tooth enamel (>95% apatite) can be analyzed reliably. Different East African herbivores exhibit previously unsuspected compositional differences. Average enamel δ18O values (V-SMOW) are approximately: 25‰ (goat), 27‰ (oryx), 28‰ (dikdik and zebra), 29‰ (topi), 30‰ (gerenuk), and 32‰ (gazelle). These compositions differ from generalized theoretical models, but are broadly consistent with expected isotope effects associated with differences in how much each animal (a) drinks, (b) eats C3 vs. C4 plants, and (c) pants vs. sweats. Consideration of diet, water turnover, and animal physiology will allow the most accurate interpretation of ancient teeth and targeting of environmentally-sensitive animals in paleoclimate studies.
UR - http://www.scopus.com/inward/record.url?scp=0030434929&partnerID=8YFLogxK
U2 - 10.1016/0016-7037(96)00248-7
DO - 10.1016/0016-7037(96)00248-7
M3 - Article
AN - SCOPUS:0030434929
SN - 0016-7037
VL - 60
SP - 3889
EP - 3896
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 20
ER -