Isotope-abundance ratios of light (bio) and heavy (geo) elements in biogenic tissues: methods and applications

Intra- and inter-individual variability of stable strontium isotope ratios in hard and soft body tissues of pigs

RATIONALE

Stable isotope analysis has become an indispensable tool for the identification of the flow of matter in ecological sciences. Stable strontium isotope ratios are used in several different scientific fields as markers for provenance, mobility, and migration. A crucial prerequisite for such studies is a reliable definition of local ranges and an estimation of expected isotopic variability.

METHODS

To study the local variability of stable strontium isotope ratios at a specific place, a farrow of ecologically and locally grown pigs was investigated and strontium was extracted from their hard tissues (tooth enamel, bones and bristles) as well as soft tissues (meat, organs and blood) via dry- and wet-ashing procedures and subsequent column separation. The ⁸⁷ Sr/⁸⁶ Sr ratio was then measured via TIMS (thermal ionization mass spectrometry).

RESULTS

Reliable ⁸⁷ Sr/⁸⁶ Sr data was generated from all tissue types. Both intra- and inter-individual variability was high and tissue-specific patterns could be identified. High ranges occurred in sample types which were analyzed for animals of different age (pigs as well as piglets): teeth, parietal, mandible, femur, and leg muscle as well as in jaw muscle samples, which were only analyzed in adult pigs. Tooth enamel data showed a tooth-type-dependent pattern.

CONCLUSIONS

We conclude that a time factor played a role for the observed variability, e.g. a shift in food supply. Furthermore, we presume that local range estimates from the literature only work for tissues which integrate all consumed components over a sufficient amount of time and average fluctuations which can be found in tissues with higher turnover rates.

Tracing the 87Sr/86Sr from rocks and soils to vine and wine: An experimental study on geologic and pedologic characterisation of vineyards using radiogenic isotope of heavy elements

In this paper we report an experimental study to assess the process of Sr-isotope uptake from the soil and its transfer to the grapevine and then to the wine made through micro-vinification. The experimental work has been carried out with a deep control of the boundary conditions (i.e., type of soil, geologic substratum, ground water supply, etc.) on 11 selected vine-plant sites over a period of four harvest years. Sr-isotopes have been determined on grape-bunches, grapevine sap, on the bioavailable fraction of the soil, on bulk soil, and on the rocks of the substratum. No significant Sr-isotope variability has been observed among micro-vinifications from different harvest years. A slight but significant Sr-isotope variability occurred among wines from rows embedded on different soil type. The Sr-isotope data on micro-vinifications well match those of grapevine sap and bioavailable fraction of soils, all of them falling well within the whole geological range of the bedrock, despite an evident decoupling between bioavailable fraction, whole soils and bedrocks does exist. This decoupling has been ascribed to differential geochemical behaviour of minerals in response to pedogenetic processes. The findings of our experiments indicate that the biological activity of the vine is not able to change the original ⁸⁷Sr/⁸⁶Sr composition up-taken from the bio-available fraction of the soil. Thus, the ⁸⁷Sr/⁸⁶Sr of the wine is an unadulterated feature of the terroir.

High-Precision In Situ 87Sr/86Sr Analyses through Microsampling on Solid Samples: Applications to Earth and Life Sciences

An analytical protocol for high-precision, in situ microscale isotopic investigations is presented here, which combines the use of a high-performing mechanical microsampling device and high-precision TIMS measurements on micro-Sr samples, allowing for excellent results both in accuracy and precision. The present paper is a detailed methodological description of the whole analytical procedure from sampling to elemental purification and Sr-isotope measurements. The method offers the potential to attain isotope data at the microscale on a wide range of solid materials with the use of minimally invasive sampling. In addition, we present three significant case studies for geological and life sciences, as examples of the various applications of microscale ⁸⁷Sr/⁸⁶Sr isotope ratios, concerning (i) the pre-eruptive mechanisms triggering recent eruptions at Nisyros volcano (Greece), (ii) the dynamics involved with the initial magma ascent during Eyjafjallajökull volcano's (Iceland) 2010 eruption, which are usually related to the precursory signals of the eruption, and (iii) the environmental context of a MIS 3 cave bear, Ursus spelaeus. The studied cases show the robustness of the methods, which can be also be applied in other areas, such as cultural heritage, archaeology, petrology, and forensic sciences.

Stable Isotope Ratio Analysis for Assessing the Authenticity of Food of Animal Origin

The main elemental constituents (H, C, N, O, and S) of bio-organic material have different stable isotopes (² H, ¹ H; ¹³ C,¹² C; ¹⁵ N,¹⁴ N; ¹⁸ O,¹⁷ O,¹⁶ O; ³⁶ S, ³⁴ S, ³³ S, and ³² S). Isotopic ratios can be measured precisely and accurately using dedicated analytical techniques such as isotope ratio mass spectrometry (IRMS). Analysis of these ratios shows potential for assessing the authenticity of food of animal origin. In this review, IRMS analysis of food of animal origin and variability factors related to stable isotope ratios in animals are described. The study also lists examples of application of stable isotope ratio analysis to meat, dairy products, fish, and shellfish and emphasizes the strengths and weaknesses of the technique. Geographical, climatic, pedological, geological, botanical, and agricultural factors affect the stable isotope ratios (SIR) of bio-elements, and SIR variations are ultimately incorporated into animal tissue through eating, drinking, breathing, and exchange with the environment, being recorded in the resulting foods. SIR analysis was capable of determining geographical origin, animal diet, and the production system (such as organic/conventional or wild/farmed) for pork, beef, lamb, poultry, milk, butter, cheese, fish, and shellfish. In the case of the hard PDO (protected designations of origin) cheeses Grana Padano and Parmigiano Reggiano it is also used in real-life situations to assess the authenticity of grated and shredded cheese on the market.

Gas collision for improving the precision and accuracy of11B/10B ratios determination in ICP-QMS and its application to determining wine provenance

Gas collision for improving the precision and accuracy of¹¹B/¹⁰B ratios determination in ICP-QMS.

The utilization of stable isotope analysis for the estimation of the geographic origins of unidentified cadavers

The number of unidentified cadavers is increasing worldwide and the effective methods which reveal their geographic origin are not well known. This study reports on the utilization of δ(18)O, δ(13)C, δ(2)H and δ(15)N ratios gained through stable isotope analysis of urine samples collected from eight locations: Chiba, Japan; Fuzhou, China; and Denpasar, Indonesia in our pilot study with data from healthy volunteers from five further locations from healthy volunteers: Melbourne and Perth, Australia; Qingdao, China; Turku, Finland and Oklahoma, USA. This study posits that the utilization of δ(18)O and δ(2)H is more feasible than δ(13)C and δ(15)N stable isotope ratios in differentiating or estimating the origin of human samples. Secondly, this study demonstrated that the δ(18)O and δ(2)H stable isotope ratios of urine samples from eight locations differed significantly.

Geographic determination of coffee beans using multi-element analysis and isotope ratios of boron and strontium

This study aims to evaluate the feasibility of using chemical and isotopic compositions of coffee beans to identify their geographic origins. Twenty-one Coffea arabica beans collected from 14 countries in 3 major coffee-producing regions, Africa, America and Asia, were analysed for multi-element of B, Rb, Sr, Ba, Fe, Mn and Zn, as well as isotopic compositions of B and Sr. Our results demonstrate that the geographic origin of coffee beans could be classified based on concentrations of Rb, Sr and Ba. However, the isotope ratios of B and Sr provide more sensitive information for the growth localities. Combined with literature data, this study indicates that B and Sr isotopes are excellent indicators of the origin of coffee beans.

High-precision 87Sr/86Sr analyses in wines and their use as a geological fingerprint for tracing geographic provenance

The radiogenic isotopic compositions of inorganic heavy elements such as Sr, Nd, and Pb of the food chain may constitute a reliable geographic fingerprint, their isotopic ratios being inherited by the geological substratum of the territory of production. The Sr isotope composition of geomaterials (i.e., rocks and soils) is largely variable, and it depends upon the age of the rocks and their nature (e.g., genesis, composition). In this study we developed a high-precision analytical procedure for determining Sr isotopes in wines at comparable uncertainty levels of geological data. With the aim of verifying the possibility of using Sr isotope in wine as a reliable tracer for geographic provenance, we performed Sr isotope analyses of 45 bottled wines from four different geographical localities of the Italian peninsula. Their Sr isotope composition has been compared with that of rocks from the substrata (i.e., rocks) of their vineyards. In addition wines from the same winemaker but different vintage years have been analyzed to verify the constancy with time of the (87)Sr/(86)Sr. Sr isotope compositions have been determined by solid source thermal ionization mass spectrometry following purification of Sr in a clean laboratory. (87)Sr/(86)Sr of the analyzed wines is correlated with the isotopic values of the geological substratum of the vineyards, showing little or no variation within the same vineyard and among different vintages. Large (87)Sr/(86)Sr variation is observed among wines from the different geographical areas, reinforcing the link with the geological substratum of the production territory. This makes Sr isotopes a robust geochemical tool for tracing the geographic authenticity and provenance of wine.

Origin assignment of unidentified corpses by use of stable isotope ratios of light (bio-) and heavy (geo-) elements—A case report

An unknown male body was found near an expressway in Germany. As different criminalistic and forensic methods (e.g. tooth status, fingerprint or DNA-analysis) could not help to identify the person, multielement stable isotope investigations were applied. The combined analysis of stable isotope ratios of light (H, C, N) and heavy elements (Pb, Sr) on the man's body tissues supported to assign him to Romania. The case report demonstrates an application of multielement-isotope analysis in the forensic fields and its potential.

Using hooves for high-resolution isotopic reconstruction of bovine dietary history

The objective of this study was to ascertain whether sequential sampling and isotopic analysis of bovine hooves could be used to reconstruct the dietary history of cattle. A controlled, on-farm experiment was conducted in which cattle were switched from a barley-based diet to an isotopically different diet incorporating maize, urea and seaweed (the isotopic spacing between diets was 13.6 per thousand for delta(13)C and 8.0 per thousand for delta(15)N) and maintained on that diet for 168 days. Postmortem sampling of the cleaned anterior wall of the lateral, left front claw was carried out on five individuals using a micro-drilling technique. From the first 60 mm of each claw, up to 41 samples with a spacing between them of less than 1 mm were collected. Bands were less than 1 mm deep and had a mean width of 1.2 mm. The hoof keratin showed a rapid increase followed by a slower increase in its delta(13)C and delta(15)N values following the diet switch, suggesting that C and N in hoof keratin originate from more than one pool. However, the response of the N isotope composition of the hoof was somewhat delayed compared with that of C. Estimated mean hoof growth rates for these cattle were 10.5 +/- 2.3 mm per month and 6.7 +/- 1.0 mm per month (+/-SD, n = 5) when receiving the barley-based transition diet and the maize-based experimental diet, respectively. These values are considerably higher than previous estimates obtained by visual methods and they suggest that diet may have a greater influence on hoof growth rates than seasonality. These results demonstrate that hooves are a suitable incremental tissue for high-resolution isotopic reconstruction of the dietary history of bovine animals.