Evaluation of neodymium isotope analysis of human dental enamel as a provenance indicator using 1013â€¯Ω amplifiers (TIMS).

Human provenance studies employing isotopic analysis have become an essential tool in forensic and archaeological sciences, with multi-isotope approaches providing more specific location estimates compared to single isotope studies. This study reports on the human provenancing capability of neodymium isotopes (143Nd/144Nd), a relatively conservative tracer in the environment. Neodymium isotope ratios have only recently been determined on human remains due to low concentrations in human dental enamel (ppb range), requiring thermal ionisation mass spectrometry (TIMS) using 1013â€¯Ω resistors. Dental elements (third molars) from 20 individuals born and raised in the Netherlands were analysed for Nd concentration (n = 12) and Nd isotope ratios (n = 15). The geological control on Nd isotope composition was examined using coupled Nd-Sr isotope analysis of the same third molar. Teeth from different geological environments were also analysed (Caribbean, Columbian, and Icelandic, n = 5). Neodymium elemental concentrations in dental elements ranged between 0.1 and 7.9 ppb (median 0.5 ppb). The Dutch 143Nd/144Nd ratios of the provinces of Limburg and Friesland were between 0.5118 and 0.5121, with Dutch 87Sr/86Sr ratios in agreement with the previously established local range (0.708-0.710). The current findings were compared to previously published results on Nd concentration and composition from Dutch individuals. The concentration of Nd and 143Nd/144Nd ratios were weakly correlated (R2 = 0.47, n = 17) in Dutch human dental enamel. The majority (n = 25, 83.3%) of individuals had Nd and Sr isotope values isotopically indistinguishable from the geological environment in which their third molars formed and mineralised. However, the Nd isotope ratios of the Icelandic individual and several Dutch individuals (n = 4) suggested that Nd in enamel is not solely influenced by geological environment. In order for neodymium isotopes to be quantitatively applied in forensic and archaeological settings further analyses of individuals from various geographical regions with well-defined dietary Nd isotope data are required.

Wet degradation of keratin proteins: linking amino acid, elemental and isotopic composition.

RATIONALE: Archaeological keratin samples are increasingly the subject of palaeodietary, provenancing and dating studies. Keratin samples from wet archaeological contexts are microbiologically and chemically degraded, causing differential diagenesis of protein structures in hair fibres. The effects of these processes on the analytical parameters of interest are currently unknown. METHODS: This study examined the impact of degradation of wool fibres on isotopic (δ(13)C, δ(15)N, un-exchangeable δ(2)H and δ(18)O values) composition. It compared two models of archaeological protein degradation in wet burial environments: (1) short term (up to 8 years) experimental burial in three contrasting soil environments; and (2) laboratory wet conditions, in which elevated temperature (80 °C, 110 °C, and 140 °C) and pressure simulated longer exposure. Elemental and amino acid (AA) composition were also measured. RESULTS: In experimentally soil-buried samples, AA, elemental and isotopic composition changes were small, despite extensive macroscopic alteration. Isothermally heated samples showed preferential loss of hydrophilic AAs (Asx, Glx, Ser, Gly) from wool residues, with depletion in (2)H and (18)O at higher temperatures (up to -73‰ change in δ(2)H and -2.6‰ in δ(18)O values). The δ(13)C and δ(15)N values showed little change except in densely pigmented samples at low temperatures only. Samples dyed with madder/alum were better preserved than undyed samples. CONCLUSIONS: Diagenesis in experimentally soil-buried wool textiles was consistent with microbiological, non-protein-selective activity, in contrast to highly AA-selective hydrolytic behaviour under laboratory wet conditions. Changes in δ(2)H and δ(18)O values were correlated with degree of AA change, but the δ(13)C and δ(15)N values were not. The results contribute to a baseline for interpreting analytical data from archaeological hair samples preserved by burial in wet environments.

Comparison of isotopic variability in proteinaceous tissues of a domesticated herbivore: a baseline for zooarchaeological investigation.

RATIONALE: A variety of metabolic, dietary and climatic influences on isotopic variation have been established in mammalian hair. The relevance of these factors to collagen isotopic composition is unknown, but would be of great interest to zooarchaeological analyses of faunal skeletal tissue. METHODS: The relationships between carbon (δ(13)C), nitrogen (δ(15)N), non-exchangeable hydrogen (δ(2)H) and oxygen (δ(18)O) values of defatted, demineralised and gelatinised bone collagen and defatted wool keratin from two sheep flocks (n = 20, 5) in the UK were investigated, including testing for the effects of nutritional plane, sex, pregnancy and season of sample collection. The sulfur composition (δ(34)S values) was also investigated for tissues from the smaller flock. RESULTS: Bulk collagen was enriched in (13)C over bulk keratin by 2.0 - 2.7‰ and in (2)H by 29 - 40‰ but depleted in (18)O relative to keratin by 1.8‰. Differences in δ(15)N values were within experimental error. The collagen samples were generally more enriched in (34)S than keratin, but this was very variable. Pregnancy, sex and season, but not nutritional plane, significantly affected isotope values but did not change overall keratin-collagen relationships. CONCLUSIONS: This dataset provides a baseline measure of variability and comparability for isotopic investigations into origin and husbandry conditions in archaeological sheep tissues, both collagen and keratin.