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

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.

Resetting of soil compositions by irrigation in urban watersheds: Evidence from Sr isotope variations in Austin, TX

Human activities in urban areas disturb the natural landscape upon which they develop, disrupting pedogenic processes and ultimately limiting the ecosystem services urban soils provide. To better understand the impacts on and resiliency of soils in response to urban development, it is essential to understand the processes by which and degree to which soil physical and chemical properties are altered in urban systems. Here, we apply the source-tracing capabilities of Sr isotopes (87Sr/86Sr) to understand the impacts of urban processes on the composition of soils in eight watersheds in Austin, Texas. We evaluate natural and anthropogenic Sr sources in watersheds spanning a wide range of urbanization, comparing soils by variations in their natural (including mineralogy, thickness, soil type, and watershed) and anthropogenic (including irrigation, soil amendments, and fertilization) characteristics. A strong positive correlation between soil thickness and 87Sr/86Sr is observed among unirrigated soils (R2 = 0.83). In contrast, this relationship is not observed among irrigated soils (R2 = 0.004). 95 % of 42 irrigated soil samples have 87Sr/86Sr values approaching or within the range for municipal supply water. These results indicate soil interaction with municipal water through irrigation and/or water infrastructure leakage. Soils irrigated with municipal water have elevated 87Sr/86Sr values relative to unirrigated soils in seven of eight watersheds. We propose that original soil 87Sr/86Sr values are partially to completely reset by irrigation with municipal water via ion exchange processes. Our results demonstrate that in urban systems, Sr isotopes can serve as an environmental tracer to assess the overprint of urbanization on natural soil characteristics. In the Austin region, resetting of natural soil compositions via urban development is extensive, and the continued expansion of urban areas and irrigation systems may affect the ability of soils to retain nutrients, filter contaminants, and provide other ecosystem services that support environmental resilience.

BITACORA: An isotopic database of modern human tissues (keratin, teeth) for Argentina

As a consequence of the recent history of Argentina related to crimes against humanity, the country has positioned itself as a leader on Forensic Anthropology in human rights contexts. To some extent it can even be argued that Forensic Genetics for human identification had its origins in human rights work in the early 1980s in Argentina. However, there are still hundreds of unidentified human remains recovered from the dictatorial regimes' crimes. Additionally, every year there are dozens of unidentified deceased buried in public cemeteries. Thus, there is an urgent need to adopt new techniques that could increase the biological profile of a person, and therefore increase the chances of positive identifications. One of such initiatives is the development of isotopic databases and models that can provide information on the population and region of origin of unidentified victims. We present the development of an isotopic database of modern human tissues named BITACORA (from its name in Spanish: Base de Información Isotópica de Tejidos Actuales Como Referencia Argentina). BITACORA holds isotopic data (δ18O, δ2H, δ13C, δ15N and δ34S values) from teeth (enamel and dentine) and keratin tissues (scalp hair, beard and fingernails) obtained from volunteers of known origin, as well as individual information of the donors (age, gender, biometrics, dietary preferences, and relocation history). BITACORA is associated with a tap water isotope database. Currently, we have 345 keratin, 273 teeth and 287 tap water samples gathered from across the country. We present preliminary analyses on the geographic distribution of these isotopic markers, and provide an overall discussion of the current status and future development of the databases.

National-scale investigation of dual nitrate isotopes and chloride ion in South Korea: Nitrate source apportionment for stream water

Nitrate sources in surface water have been identified using dual-isotope compositions of nitrate with various tools to efficiently manage the water quality at the local scale. Correlation between Cl and NO₃ has also been used to identify NO₃. In this study, we assess the reliability of the dual-isotope approach and Cl in terms of nitrate source apportionment. To this end, we collected stream water samples throughout South Korea to estimate nitrate sources in streams and determine whether the land-use pattern was closely related to nitrate sources. The δ¹⁵N-NO₃ ranging from -1.3 to 14.8‰ showed a spatial distribution that was lower in mountain ranges (<7‰) than plain areas (>8‰). The Cl concentration in this national-scale distribution was also assessed. The relationship between the proportion of Cl and δ¹⁵N-NO₃ classifies nitrate sources into areas characterized by three land-use patterns: (1) agricultural and business areas, (2) forests in highlands, and (3) lowland forests, of which (1) had proportions of Cl >50%, while (2) and (3) were <50%. The samples in (3) showed δ¹⁵N-NO₃ values > 6‰, similar to those of (1). Deuterium excess of samples was negatively correlated (R² = 0.53) with δ¹⁵N-NO₃, accounting for the fact that δ¹⁵N-NO₃ reflected land-use patterns. Samples were dominantly affected by agriculture-derived sources and domestic sewage showed NO₃/Cl of <0.4 and δ¹⁵N-NO₃ of >6‰. These results suggest that nitrate source apportionment should be comprehensively evaluated considering the dual-isotope approach, land-use patterns, and Cl proportions.

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.

Tracing the geographical origin of bottled water collected in South Korea via isotopic and elemental analyses

RATIONALE

The production of bottled water requires a forensic discriminant technique that enables the identification of the brands or accidents caused by intended contaminants. The bottled water poisoning crimes have drawn much attention, and such crimes may recur in the future. The water is colorless and odorless, and thus it is difficult to detect contaminated water through visual observation. Thus, bottled water can be easily exploited for poisoning, and a method for tracing their origin is currently required.

METHODS

In this study, a total of 27 brands of bottled water samples were analyzed to determine stable oxygen isotopes, strontium isotopes, major and trace elements. The geographical origin of the water was traced based on the climatic and geographical characteristics of the location from where water was sourced, which was assumed to be reflected in the bottled water. Furthermore, we investigated whether this method can be applied to identify bottled water products.

RESULTS

The results demonstrated that the characteristics of the bottled water, including the oxygen stable isotope ratios, reflect the latitude and altitude of bottled water source in South Korea, from the high-latitude region to the coastal regions. In addition, the results indicated that excellent discrimination was achieved using strontium isotopes to identify source areas with different types of bedrock, complex underlying lithologies, and ocean areas in South Korea. A statistical method based on discriminant analysis was applied to measure trace elements, and the results effectively reflected the characteristics of water-rock interactions (cross-validated classification probability: ≥92%).

CONCLUSIONS

These data suggest that the geographical characteristics of the source area are well reflected in commercial bottled water in South Korea. The proposed analytical methods can be utilized to trace the geographical origin of different bottled water samples and identify bottled water products used in poisoning crimes.

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.

Elemental Analysis of Laryngeal Cancer Patients in Comparison with Controls Using Scalp Hair as an Analytical Tool

Laryngeal cancer, a rare form of head and neck cancer, is more common in men, and various factors play important roles in its etiology. In the current study, trace elemental contents in the scalp hair of laryngeal cancer patients and healthy subjects were evaluated. Selected essential and toxic elements were measured using flame atomic absorption spectrophotometry after the hair samples were digested with HNO₃-HClO₄. The mean/median levels of Pb in the scalp hair of patients were significantly higher than the healthy donors, but Sr, Zn, and Co exhibited comparatively lower levels in the laryngeal cancer patients. In comparison to healthy donors, the correlation pattern among the elements in the hair of the patients exhibited diverse mutual relationships. The multivariate apportionment of the elemental levels in the scalp hair of both donor groups was significantly divergent. The average elemental levels varied significantly among the cancer types (glottic, supraglottic, transglottic, and subglottic) as well as the cancer stages (I, II, III, IV). The average levels of the elements also exhibited considerable variations depending on the donors' habitat, gender, food, and smoking habits. Overall, the study revealed significantly divergent disparities among the elemental contents in the scalp hair of the laryngeal cancer patients in comparison with counterpart controls.

Use of strontium isotope ratios in geolocation of Guatemalan population: Potential role in identification of remains

Within post‐conflict communities, attempts to identify and repatriate unidentified and missing individuals poses a difficult task. As current forensic strategies commonly lack the capacity to provide region of origin assessments, forensic anthropologists/investigators are often unable to identify sources of DNA for kinship analysis. Using Thermal Ionization Mass Spectrometry (TIMS), hair samples from 10 volunteers were used to assess the variation in strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) between extant people in Guatemala City and Coban; with a leach (external) and digest (dietary) signal analyzed for each sample. A two‐way anova demonstrated that the difference between ⁸⁷Sr/⁸⁶Sr of Guatemala City and Coban was statistically significant (F [1, 16] = 259.839, p < 0.05), with no statistically significant differences observed between leach and digest ⁸⁷Sr/⁸⁶Sr (F [1,16] = 4.319, p = 0.054). Overall, individuals from Coban demonstrate ⁸⁷Sr/⁸⁶Sr comparable to previously recorded baseline values, demonstrating a minimal change in diet which is reflected in associated surveys. Volunteers from Guatemala City, however, show a marked shift in ⁸⁷Sr/⁸⁶Sr away from predicted values highlighting the potential influence of imported goods. The results here highlight the applicability of ⁸⁷Sr/⁸⁶Sr in hair to serve as a potential tool to support the identification of unknown individuals in Guatemala in a forensic context.