Light Stable Isotope Ratios Research Articles

A synergistic solution for fighting fraudulent practices in squid using light stable isotope ratios and lanthanide tracers

To identify a novel optimized strategy for preventing fraudulent substitutions of squid species and origins, forty European squids (Loligo vulgaris) and forty flying squids (Todarodes sagittatus) from the Mediterranean Sea and Atlantic Ocean were analyzed for δ13C, δ15N, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu using isotope ratio mass spectrometry and inductively coupled plasma-mass spectrometry. While δ13C and δ15N variations were mainly species-related, they alone could not reliably distinguish samples. To address this issue, decision rules were developed using Classification and Regression Tree analysis. Threshold values for δ13C (−19.91‰), δ15N (14.87‰), and Pr (0.49 μg kg−1) enabled successful discrimination among Mediterranean European squids, Atlantic European squids, Mediterranean flying squids, and Atlantic flying squids, achieving over 90% accuracy, 81% precision, 80% sensitivity, and 93% specificity. This method holds promise for enhancing traceability and safety in the seafood industry, ensuring product integrity and consumer trust.

Isotopic Characterization of Italian Industrial Hemp (Cannabis sativa L.) Intended for Food Use: A First Exploratory Study

In this study, Italian industrial hemp (Cannabis sativa L.) intended for food use was isotopically characterized for the first time. The stable isotope ratios of five bioelements were analyzed in different parts of the plant (i.e., roots, stems, inflorescences, and seeds) sampled in eight different regions of Italy, and in five hemp seed oils. The values of δ2H, δ13C, δ18O, and δ34S differed according to the latitude and, therefore, to the geographical origin of the samples and the climate conditions of plant growth, while the δ15N values allowed us to distinguish between crops grown under conventional and organic fertilization. The findings from this preliminary study corroborate the reliability of using light stable isotope ratios to characterize hemp and its derived food products and contribute to the creation of a first isotopic database for this plant, paving the way for future studies on authentication, traceability, and verification of organic labeling.

Isotope applications to soil science at the University of Alberta — an historical perspective

For the past 70 yr, researchers in the Soil Science/Renewable Resources Department at the University of Alberta have used isotopes to study topics of ecological importance. This review highlights the soil isotope research conducted within our department over this time, including an historical overview of studies of interest. Analytical techniques and advances in instrumentation are discussed, focusing on the measurement of light stable isotope ratios (i.e., for C, H, N, S, and O) using isotope ratio mass spectrometry (IRMS). Early soil isotope work (1950–2000s) focused on agricultural soils and soil fertility issues. These studies included the use of radioactive isotopes such as 14C and 35S, and (or) artificially enriched stable isotopes including 15N-labelled fertilizers. More recently (2000–present), the scope of research widened to include natural-abundance stable isotope ratio studies as higher-sensitivity IRMS systems became more prevalent. Current isotope research topics include N biogeochemistry in natural and managed ecosystems, land management effects on greenhouse gas emissions, carbon cycling in northern landscapes, paleo-reconstruction in peatlands, carbon sequestration in boreal forests, and biodegradation of petroleum hydrocarbons. Further technological progress also enabled new techniques such as compound-specific IRMS analysis, including δ13C and δ2H measurements of soil n-alkanes and phospholipid fatty acids. In conclusion, current IRMS instrumentation presents unparalleled opportunities for multidisciplinary research to track carbon, plant nutrients, and pollutants as they move through soils.

Combination of stable isotopes and multi-elements analysis with chemometric for determining the geographical origins of Rhizoma Coptidis

Rhizoma Coptidis is a valuable medicine food homology plant, whose geographic origin is a topic of interest to both consumers and producers since the geographic origin determines its prices and efficacy. A novel method for discriminating the geographic origins of Rhizoma Coptidis was established based on stable isotopes and multi-elements analysis combined with chemometric. Then, 4 light stable isotope ratios and 32 inorganic elements of 103 samples from six regions were determined. The results showed that the isotopes ratios and multi-elements contents were significantly different among Rhizoma Coptidis from six regions. Al, Sn, Mg, δ15N and δ13C (VIP > 1.5) were considered as the most powerful differentiation markers for discriminating the geographical origins. In addition, by linear discriminant analysis (LDA) and orthogonal partial least squares discriminant analysis (OPLS-DA), all samples were successfully classified with 100% accuracy. Based on the built predictive model, the origin of unknown samples were successfully predicted with 100% accuracy. The parameters of the models R2X, R2Y and Q2 were 0.999, 0.900 and 0.854, respectively. Therefore, the stable isotopes and multi-elements analysis combined with chemometric tools can be successfully used to discriminate the geographic origins of Rhizoma Coptidis.

Characterisation and geographical traceability of Italian goji berries

This work characterises and distinguishes Italian and Asian goji berries, combining three analytical approaches to determine 5 light stable isotope ratios, 57 mineral elements and 14 carotenoids.The study analyses stable isotope ratios and provides full HPLC-DAD-MS characterisation of the carotenoid fraction in goji berries for the first time. The isotopic composition of Italian berries was characterised by δ13C values ranging between −28.2‰ and −25.7‰, δ15N between 2.3 and 7.3‰, δ34S between 2.6 and 7.9‰, and D/H between −112 and −49‰.Italian goji berries were shown to have a particular composition and interesting nutritional characteristics, specifically a higher total carotenoid content (355 mg/100 g dw mean content vs 198 mg/100 g dw) and higher content of some micronutrients: K, B, Cu, Mo, Se, and Zn.On the basis of δ34S, Y, U, Cu, Rb, zeaxanthin palmitate and total carotenoid content, discriminant analysis correctly classified all samples according to their geographical origin.

Interindividual differences in embodied marginalization: Osteological and stable isotope analyses of antebellum enslaved individuals.

Through pathological and stable isotope analyses, this study probes the stressors, disease ecology, and diets of enslaved individuals from an antebellum plantation cemetery. The study aims to highlight how interindividual isotopic differences reveal that marginalization is not uniformly experienced or embodied. The cemetery population consists of 16 individuals; dental and skeletal pathological indicators were collected for all individuals, and light stable isotope ratios (δ15 N, δ13 C) were generated from the collagen and hydroxyapatite of nine individuals. The analyzed individuals have high frequencies of enamel defects-similar to contemporaneous enslaved cemetery individuals-and particularly high frequencies of carious lesions. Skeletal analysis shows evidence of chronic conditions among several individuals, two of whom likely have tuberculosis. Although the sample size is small, stable isotope values display interesting trends: there is interindividual heterogeneity in δ13 C values, and most subadults from the cemetery have lower δ15 N and higher δ13 C values than the sampled adults. These relationships can be tested with larger datasets and have the potential to reveal important information about slave foodways and the broader experience of enslavement. The results of this study suggest that racial discrimination, enslavement, and age do not fully account for the heterogeneity in degree of embodied stressors. There are likely other factors at play, intersecting with the aforementioned, that influenced the lived experience of slavery and the degree of marginalization.

Equilibrium Fractionation of Non-traditional Stable Isotopes: an Experimental Perspective

In 1986, O’Neil wrote a Reviews in Mineralogy chapter on experimental aspects of isotopic fractionation. He noted that in order to fully understand and interpret the natural variations of light stable isotope ratios in nature, it was essential to know the magnitude and temperature dependence of the isotopic fractionation factor amongst minerals and fluids. At that time it was difficult to imagine that this would become true for the heavier, so called non-traditional stable isotopes, as well. Since the advent of the multiple collector inductively coupled plasma-source mass spectrometer (MC–ICP–MS), natural variations of stable isotope ratios have been found for almost any polyisotopic element measured. Although it has been known that as temperature and mass increase, isotope fractionation decreases very quickly, the MC–ICP–MS has revolutionized the ability of a geochemist to measure very small differences in isotope ratios. It was then that the field of experimental non-traditional stable isotope geochemistry was born. As O’Neil (1986) pointed out there are three ways to obtain isotopic fractionation factors: theoretical calculations, measurements of natural samples with well-known formation conditions, and laboratory calibration studies. This chapter is devoted to explaining the techniques involved with laboratory experiments designed to measure equilibrium isotope fractionation factors as well as the best practices that have been learned. Although experimental petrology has been around for a long time and basic experimental methods have been well-refined, there are additional considerations that must be taken into account when the goal is to measure isotopic compositions at the end of the experiment. It has been only about ten years since these initial studies were published, but much has been learned in that time about how best to conduct experiments aimed at determining equilibrium fractionation factors. We will not focus on the scientific results that have been determined by such experiments, as each …

A distinct section of the early bronze age society? Stable isotope investigations of burials in settlement pits and multiple inhumations of the Únětice culture in central germany

Inhumations in so-called settlement pits and multiple interments are subordinate burial practices of the Early Bronze Age Únětice culture in central Germany (2200-1700/1650 BC). The majority of the Únětice population was entombed as single inhumations in rectangular grave pits with a normative position of the body. The goal of the study was to test archaeological hypotheses that the deviant burials may represent socially distinct or nonlocal individuals. The study comprised up to two teeth and one bone each of 74 human individuals from eight sites and faunal comparative samples. The inhumations included regular, deviant burials in so-called settlement or storage pits, and multiple burials. We investigated radiogenic strontium isotope compositions of tooth enamel ((87) Sr/(86) Sr) and light stable isotope ratios of carbon and nitrogen of bone collagen (δ(13) C, δ(15) N) aiming at the disclosure of residential changes and dietary patterns. Site-specific strontium isotope data ranges mirror different geological properties including calcareous bedrock, loess, and glacial till. Independent from burial types, they disclose low portions of nonlocal individuals of up to some 20% at the individual sites. The light stable isotope ratios of burials in settlement pits and rectangular graves overlap widely and indicate highly similar dietary habits. The analytical results let to conclude that inhumations in settlement pits and multiple burials were two of the manifold burial practices of the Early Bronze Age. The selection criteria of the individuals for the different forms of inhumation remained undisclosed.

Isotopic ecology of fossil fauna from Olduvai Gorge at ca 1.8 Ma, compared with modern fauna

Light stable isotope ratios (δ13C and δ18O) of tooth enamel have been widely used to determine the diets and water sources of fossil fauna. The carbon isotope ratios indicate whether the plants at the base of the food web used C3 or C4 photosynthetic pathways, while the oxygen isotope ratios indicate the composition of the local rainfall and whether the animals drank water or obtained it from plants. The contrasting diets of two early hominin species – Homo habilis and Paranthropus boisei – of ca 1.8 Ma (million years ago) in Tanzania were determined by means of stable carbon isotope analysis of their tooth enamel in a previous study. The diets of two specimens of P. boisei, from Olduvai and Peninj, proved to be particularly unusual, because 80% of their carbon was derived from C4 plants. It was suggested that their diet consisted primarily of plants, with particular emphasis on papyrus, a C4sedge. The dominance of C4 plants in the diet of P. boisei is a finding supported in another study of 22 specimens from Kenya. The isotopic ecology and diets of fossil fauna that were present at the same time as the two fossil hominin species are described here, in order to provide a fuller understanding of their contrasting diets and of the moisture sources of their water intake. This information was then compared with the isotopic composition of modern fauna from the same region of Tanzania. The carbon isotope ratios for both fossil and modern specimens show that the habitats in which these faunal populations lived were quite similar – grassland or wooded grassland. They had enough bushes and trees to support a few species of browsers, but most of the animals were grazers or mixed feeders. The oxygen isotope ratios of the fossil and modern fauna were, however, very different, suggesting strongly that the source of moisture for the rain in the Olduvai region has changed during the past 1.8 million years.

Measurement of light stable isotope ratios by SIMS:: Matrix effects for oxygen, carbon, and sulfur isotopes in minerals

Mass bias occurring during analysis of the light stable isotopes of oxygen, carbon, and sulfur in geological materials by secondary ionization mass spectrometry has been investigated. The effects of instrumental parameters (primary ion beam, secondary ion energy, and polarity) were evaluated by measuring sulfur isotope ratios in conductive sulfide minerals. The role of analyte chemical composition (matrix effect) on mass bias was investigated in sulfides (sulfur), silicates and oxides (oxygen), and carbonates (oxygen and carbon). For oxygen and carbon, various correlations between mass bias and matrix parameters have been identified. The application of several empirical models for prediction of oxygen isotopic mass bias indicates that for silicates, depending on mineral composition, bias can be predicted with an accuracy that is typically within two times that of the precision. However, extension of these models to other matrices has proved problematic, indicating that additional factors are important.

Role of organic matter and sulphate-reducing bacteria for metal sulphide precipitation in the Bahloul Formation at the Bou Grine Zn/Pb deposit (Tunisia)

The origin of the Bou Grine Zn/Pb deposit of Tunisia was investigated during a geochemical study of the Cretaceous Bahloul Formation. The inorganic and organic chemical compositions of the bituminous marls and limestones, as well as the light stable isotope ratios of organic carbon and carbonates were measured. Closely spaced samples were collected along two profiles, at different distances from the enrichments in Zn and Pb, which are best developed near the Bou Grine diapir. The organic geochemical data suggest sulphide precipitation at the Bou Grine deposit by sulphate-reducing bacteria (SRB). SRB utilized hydrocarbons derived both from the Bahloul sediments and from external source rocks. Production of S(-II) by the bacteria was most probably limited by the availability of sulphate, although, sulphate was available to the bacteria in high concentrations in close proximity to the Triassic salt dome. Ground waters evolved to hypersaline basinal brines by dissolution of salt and anhydrite at the contact of the diapir. These brines would have been capable of leaching metals from the sedimentary sequences adjacent to the salt dome. The Triassic series has often been advocated as the source of the metals, and the Cretaceous sediments themselves are carriers of metallic elements. Ore deposition apparently resulted when metal-bearing solutions that migrated upward into the roof zone of the diapir, mixed with S(-II)-bearing solutions. Those formed when SRB oxidized the high amounts of hydrocarbons within the Bahloul sediments and in the brines, using SO 4 2− from sulphate-rich waters in the anhydrite caprock as an oxidant.

Palaeoceanography of the early Zechstein Sea during Kupferschiefer deposition in the Lower Rhine Basin (Germany): A reappraisal from stable isotope and organic geochemical investigations

Abstract In the study area of the Lower Rhine Basin the Permian Kupferschiefer was deposited in a shallow water environment. Water exchange from this marginal basin with the Zechstein Sea was restricted by palaeohighs. The burial depth of the shale did not exceed 1000 m during the depositional history of most parts of the basin. Maturation of the organic matter was governed only by the geothermal gradient not exceeding 68°C/km during the Late Carboniferous. Due to minor thermal alteration of organic matter, diagenetic effects on the biomarker composition and the light stable isotope ratios (C, H, O, N) of organic matter and carbonates are of minor importance. In the present study, isotopic and organic geochemical data are interpreted with respect to palaeoceanographic aspects. The data provide information about salinity variations, the nature of organisms living in the water column and the importance of bacterial activity in the sediment during deposition. From the degree of methylation of 2-methyl-2-trimethyl-tridecylchromans (MTTC) an euhaline to mesohaline (30–40‰) sea water salinity during Kupferschiefer sedimentation can be inferred. The high abundance of biomarkers derived from green/purple sulphur bacteria suggests H2S saturation of the bottom waters and maximum water depths below 100 m in the basin because these organisms live near the boundary between the photic zone and the anoxic (euxinic) bottom water at a depth of 10–30 m. Primary production in the upper water column was dominated by photosynthetic cyanobacteria or green algae. In the sediment, sulphate reduction occurred due to the availability of abundant sulphate and organic detritus from the overlying water column. Furthermore, methanogenesis was active mostly during early Kupferschiefer deposition. This is reflected by the light carbon isotopic composition of organic matter originating from recycling of CO2 generated by methane-oxidizing bacteria in the water column. Saccate pollen are the only morphologically preserved organic matter in the sediment.

Stable isotope studies on Bougainville and in Matupi Harbour, New Britain, Papua New Guinea

Summary Two case histories are presented in which light stable isotope ratios (D/H and 18 O/ 16 O) place important constraints on the origins of ore-forming fluids in the Panguna porphyry copper deposit (upper Pliocene) and on the nature of the volcanic exhalative environment at Matupi Harbour, near Rabaul. At Panguna the overlap in δD values between local meteoric water and inferred primary magmatic waters poses problems in the interpretation of secondary biotite and sericite isotope data. The range of hydrogen and oxygen isotope ratios of the secondary biotites associated with the mineralized areas is essentially identical to those from other magmatic hydrothermal deposits, including porphyry copper deposits. The sericites from alteration haloes adjacent to mineralized quartz veins have δ 18 O values of 5.4 to 8.6‰ and δ D values of −61 to −77. A combination of thermodynamic and fluid inclusion techniques indicates that ∼500°C is a realistic average temperature for much of the mineralization-quartz veining-biotitization process. The isotopic composition of the fluids causing this mineralization and alteration was δ D⋍ −20 to −45‰ and δ 18 O ⋍ 6 to 7‰. If a meteoric water component existed at this stage of alteration, meteoric water/rock ratios were extremely small (less than 0.05 at %). Assuming that sericitization took place at temperatures down to 300°C, as suggested by the fluid inclusion data, the fluids responsible for this process had a composition of δ D = −30 to −50‰ and δ 18 O of ⋍ 3.5‰. These fluids probably would be largely of meteoric hydrothermal origin, produced by 18 O shifting of groundwaters during the formation of the propylitic zone and with a water/rock ratio of about 0.01 at % for the entire propylitic zone. Quartz δ 18 O values from veins associated with the different alteration assemblages increase away from intrusive centres, consistent with an outwards temperature decline, a decrease in δ 18 O content of associated water and a progressive increase in the meteoric water component associated with the later and (?) lower-temperature sericitization. There is no isotopic evidence to suggest that sea waters or connate waters formed a recognizable component of the hydrothermal system at any stage. Calculations with possible δ 18 O depletions of 0.5–1.0‰ in whole rocks from the Panguna region indicate that a meteoric leaching model for the genesis of the Panguna copper deposit is theoretically possible, but unlikely because of the small water/rock ratios. The area around Matupi Harbour includes the dormant volcanoes Rabalanakaia and Tavurvur, set in loosely consolidated, Quaternary ash deposits. Tavurvur last erupted in 1941 and 1942 and has since reverted to a quiet solfataric condition. D/H and 18 O/ 16 O ratios were determined on fumarole condensates, hot springs and meteoric waters. The data are grouped into distinct areas close to the meteoric water line and demonstrate that the thermal springs away from the shoreline are of meteoric origin and that sea water only enters the springs at the shoreline. If allowance is made for the vapour-liquid separation at the temperature of collection (100°C), the fumarole results from Tavurvur may be interpreted as steam separating from a water phase at ⋍ 100°C. The calculated water-phase isotopic compositions suggest that evaporation and possibly a small amount of mixing with sea water are involved. These conclusions are in conflict with those drawn from anion ratio and trace metal contents inferred by previous authors to be consistent with an hypothesis of modified sea-water origin. We contend that the chemistry is a reflection of the later history of these acid, mineralized, geothermal waters and does not necessarily give a correct picture of their ultimate origin. The markedly enhanced Fe, Mn and Zn values of the Matupi springs are purely a function of the leaching potential of geothermal fluids at elevated temperatures and of the chemistry of the porous rocks through which they pass.