Spatial patterns in 87Sr/86Sr ratios in modern human dental enamel and tap water from the Netherlands: Implications for forensic provenancing

Enhancing the contemporary human and water isotope reference database for the Netherlands: New insights from Sr-O-C-N-H isotope data

The determination of an individual's geographic origin is an essential aspect of forensic investigations. When primary identifiers cannot be used to make a positive identification, isotope analysis can be utilized to provide new leads. Modern reference data are essential for accurate interpretation of human isotopic data in terms of diet and origin. This article presents Sr-O-C-N-H isotope data of modern individuals (hair, dental enamel, and dentine collagen) and drinking water from the Netherlands. The δ15N values of human hair fall within the range of values observed worldwide and cannot be utilized to differentiate from other countries. Distinct disparities in the hair δ13C are evident between European countries and other regions, making it possible to exclude the Netherlands as a region of origin. Comparing Dutch dental isotope data to those of other nations has proven difficult due to the limited availability of reference data. The same limitation applies to tap water δ2H data.

Isotopic analysis of formula milk reveals potential challenges in geolocating bottle-fed babies

In forensic investigations involving the identification of unknown deceased individuals, isotope analysis can provide valuable provenance information. This is especially pertinent when primary identifiers (i.e., DNA, dactyloscopy, etc.) fail to yield matches. The isotopic composition of human tissues is linked to that of the food consumed, potentially allowing the identification of regions of origin. However, the isotopic composition of deceased newborns and infants fed with milk formula may be influenced by that of the prepared milk. The findings contribute towards the possibility to isotopically identify bottle-fed infants. More importantly, the data convincingly show that the Sr isotope composition of the prepared milk is determined by that of the formula and not the (local) tap water, thereby limiting the potential of Sr isotope analysis for determining the geological or geographical origin in formula-fed babies in medico-legal cases.

National-scale distribution of strontium isotope ratios in environmental samples from South Korea and its implications for provenance studies

Successful application and accurate interpretation of strontium (Sr) isotope ratios (⁸⁷Sr/⁸⁶Sr) requires underlying information about the large-scale variabilities in their signatures from a variety of environmental samples, which can be correlated with the Sr isotopic signatures of underlying local geology. In this national-scale study, we analyzed ⁸⁷Sr/⁸⁶Sr in soil, plants, stream water, and Chinese mystery snail (Cipangopaludina chinensis) shells collected from South Korea to evaluate large-scale spatial variabilities, interpret relationships among isotopic signatures of various sample types, and generate spatial distribution isoscapes reflecting the heterogeneity of isotopic signatures across South Korea. Non-parametric comparisons among environmental samples showed non-significant differences in their isotopic ratios. The ⁸⁷Sr/⁸⁶Sr of plant and soil samples were strongly correlated (R²_adj = 0.93), suggesting that both reflect national-scale lithological properties. Similarly, the ⁸⁷Sr/⁸⁶Sr of shells showed strong correlations with the ⁸⁷Sr/⁸⁶Sr of both plant and soil samples (R²_adj = 0.90). The ⁸⁷Sr/⁸⁶Sr signatures of environmental samples in this study aligned with expected Sr isotopic values and generally reflected local geology. Spatial distribution maps of samples showed similar ⁸⁷Sr/⁸⁶Sr spatial patterns, with high radiogenic values from granitic and granitic gneiss rocks systems and low radiogenic values from volcanic and sedimentary rock systems. Stream water samples showed significant correlations with soil and plant isotopic ratios, but with a low coefficient of determination (R²_adj = 0.68). The deviations were much larger for samples with ⁸⁷Sr/⁸⁶Sr > 0.720. Further study is needed to improve the accuracy of baseline determination and interpretation of stream water isotopic variations.

Pilot study on provenance tracing of cocoons via strontium isotopes

Isotopic analysis has seen significant use in archaeological sciences to date objects, determine their origin, and depict ancient human dietary habits. However, the potential of this technique for provenance studies of ancient silks remains underdeveloped. In this study, we applied Sr isotopic ratios to the provenance tracing of silkworm cocoons. We investigated the ⁸⁷Sr/⁸⁶Sr ratios of cocoons from seven Chinese provinces to determine their regional differences. The ⁸⁷Sr/⁸⁶Sr ratios of mulberry leaves and cocoons in Shandong and Sichuan were analyzed and silkworms were cultured at four sampling locations in Hangzhou, Zhejiang, to determine isotopic signature relationships between mulberry leaves and cocoons. Those results showed that the ⁸⁷Sr/⁸⁶Sr signature of cocoons not only reflected regional differences, but also was related to the type of soil in each sampling location from which the samples were collected. It is suggested that the Sr isotope ratios was able to be an effective tool for the provenance tracing of cocoons. The Mann-Whitney test result indicated no significant differences in isotopic ratios between mulberry leaves and cocoons. In other words, mulberry leaves may predict mean isotopic values in the cocoons. No clear evidence of Sr isotopic fractionation was found in our control experiments. However, mulberry leaves and cocoons from Sichuan did not show significant correlation between them, overall reducing the predictive power of the ⁸⁷Sr/⁸⁶Sr ratios of mulberry leaf for provenance studies of cocoons. Finally, in order to improve the accuracy of Sr isotope ratios for the provenance tracing of cocoons, more ⁸⁷Sr/⁸⁶Sr data should be complemented and the relationship needs to be established between Sr isotope information in more kinds of proxies and cocoons.

Spatial distributions of strontium isotope ratios in human hair and tap water from South Korea

Natural variations of ⁸⁷Sr/⁸⁶Sr ratios in biological samples, such as human hair, provide a biological record of provenance. Spatial distribution maps reflecting heterogeneity in isotopic signatures across large geographical regions are helpful for discerning the provenance and mobility of organisms. In this national-scale study conducted across South Korea, we investigated the spatial distribution patterns of ⁸⁷Sr/⁸⁶Sr ratios in human hair and tap water samples to determine their spatial variabilities and the relationships of isotopic signatures between hair and tap water. The strontium isoscapes of tap water and hair showed similar spatial distribution patterns. Non-parametric comparison indicated no significant differences in isotopic ratios between the two sample types. The ⁸⁷Sr/⁸⁶Sr ratios in human hair showed a significant and strong correlation with the ratios in tap water in eastern Korea, suggesting potential use of ⁸⁷Sr/⁸⁶Sr ratios in provenance studies. However, tap water and hair samples from western Korea did not show significant correlation between them, overall reducing the predictive power of the hair ⁸⁷Sr/⁸⁶Sr ratios for provenance studies. The deviation between ⁸⁷Sr/⁸⁶Sr_{tap water} and ⁸⁷Sr/⁸⁶Sr_hair was much larger in western coastal areas than in eastern Korea. Relatively high utilization of groundwater or exogenous materials, such as Asian dust, may have been responsible for this pattern. To fully utilize the potential of the strontium isotope signature as a biorecorder in provenance studies, it is essential to evaluate the effects of groundwater and other exogenous materials on the isotope signatures of hair and other biological samples. In this study, only hair samples from males were used to develop ⁸⁷Sr/⁸⁶Sr isoscapes. Therefore, further studies are required to examine the applicability of ⁸⁷Sr/⁸⁶Sr hair isoscapes based solely on human hair samples from males to forensic and provenance studies of human hair samples from females.

Neodymium isotopes in modern human dental enamel: An exploratory dataset for human provenancing

This collection presents data on neodymium isotopes from modern dental elements (third molars) of 47 individuals born and raised in the Netherlands, Grenada, Curaçao, Bonaire, Columbia and Iceland. Neodymium isotope composition was successfully analyzed for 40 individuals (ranging between 0.511820 and 0.512773 143Nd/144Nd and -16.0 to 2.6 εNd), with neodymium concentration data available for 23 individuals (ranging between 0.1 and 21.0 ppb). For 37 individuals the dental elements have also been analyzed for strontium isotopes. All analyses were performed on a Thermo Scientific Triton Plus TIMS. Neodymium analyses were performed using 1013 Ω resistors, with samples reanalyzed using 1011 Ω resistors if enough sample was available. Strontium analyses were performed using 1011Ω resistors. A discussion about the applicability of the analysis technique and the results can be found in the article "Evaluation of neodymium isotope analysis of human dental enamel as a provenance indicator using 1013 Ω amplifiers (TIMS)". This dataset is available for verification of the provenance capability of neodymium isotope analysis in archaeological and forensic mobility studies. To ensure the interoperability and reusability of the data, the data is available on the IsoArcH (https://isoarch.eu/) data repository.

Identification of a female murder victim found in Burgenland, Austria in 1993

In 1993, the skeletal remains of a female corpse were found in Burgenland, Austria. Initial identification of the approximately 25–35-year-old female appeared impossible, but the case was reopened 23 years later. By applying biogeochemical isotope methods to her body tissues, the geographical origin of the unknown corpse could be predicted. The results of the C, N, S, H, Sr, and Pb isotope analyses suggested that the female did not originate from Europe and most likely spent her youth in the northern Caribbean. Using these findings, the police were able to identify the woman within 2 weeks. The female came from the Dominican Republic and resided in Austria for only a short period before she was murdered. This case shows that isotope biogeochemistry investigations can provide the police with crucial information that enables unknown persons to be identified.

Keypoints

C-N-S-H and Sr-Pb isotope analyses were applied to human remains associated with a cold case.

It was possible to determine the region of origin of the unknown deceased individual as the northern Caribbean.

After 23 years, the murder victim was successfully identified.

On the premises of mixing models to define local bioavailable 87Sr/86Sr ranges in archaeological contexts

In archaeological mobility studies, non-local humans and animals can be identified by means of stable strontium isotope analysis. However, defining the range of local ⁸⁷Sr/⁸⁶Sr ratios is prerequisite. To achieve this goal, proxy-based mixing models have recently been proposed using ⁸⁷Sr/⁸⁶Sr ratios measured in modern local vegetation, water and soil samples. Our study complements earlier efforts by introducing archaeological animal bones as an additional proxy. We then evaluate the different modelling approaches by contrasting proxy-results generated for the county of Erding (Upper Bavaria, Germany) with a comprehensive set of strontium measurements obtained from tooth enamel of late antique and early medieval human individuals (n = 49) from the same micro-region. We conclude that current mixing models based on environmental proxies clearly underestimate the locally bioavailable ⁸⁷Sr/⁸⁶Sr ratios due to the limited sample size of modern environmental specimens and a suit of imponderables inherent to efforts modelling complex geobiological processes. In sum, currently available mixing models are deemed inadequate and can therefore not be recommended.

Comparison of strontium isotope ratios in Mexican human hair and tap water as provenance indicators

Deceased undocumented border crossers are some of the most difficult individuals to identify due to the inability to narrow down the region of origin and therefore to obtain family reference samples for DNA comparison. The isotopic compositions of various body tissues have been demonstrated to be useful biomarkers for tracking locations and movements to aid in the identification of human remains. This study closes the large spatial gap of available ⁸⁷Sr/⁸⁶Sr ratios from North America in tap water and presents the first ⁸⁷Sr/⁸⁶Sr human tissue-based ratios from Mexico. The 101 hair samples from 32 locations in Mexico range in ⁸⁷Sr/⁸⁶Sr ratios from 0.70424 to 0.71613 (ΔSr_max-min=0.01189). Furthermore, 151 tap water samples from 51 locations range between 0.70404 to 0.71385 (ΔSr_max-min=0.00981). Overall, small variations in the hair and tap water samples collected from individual locations were recorded (ΔSr_max-min=0.00041 and 0.00034 respectively). Despite the fact that Mexico is one of the largest bottled water consumers in the world, the ⁸⁷Sr/⁸⁶Sr ratios of human hair and tap water correlated strongly (R²=0.87 for location averages and R²=0.80 when using individual data points). These data represent a valuable resource for identifying the provenance of human remains.