Isotope Analysis Research Articles

Degradation study of δ-hexachlorocyclohexane by iron sulfide nanoparticles: elucidation of reaction pathway using compound specific isotope analysis and pH variation

pH influences the reactivity of iron (II) minerals towards halogenated pollutants like hexachlorocyclohexanes (HCHs). To explore these incompletely understood interactions, we investigated the carbon isotope fractionation of the δ-HCH isomer during dehalogenation by iron sulfide at pHs spanning a pH range across slightly acidic to alkaline domains (5.8 to 9.6). The δ-1,3,4,5,6-pentachlorocyclohex-1-ene (δ-PCCH) was the intermediate degradation product, while benzene, monochlorobenzene (MCB), but especially 1,2-dichlorobenzene (1,2-DCB), and 1,2,4-trichlorobenzene (1,2,4-TCB), were the main degradation products of δ-HCH. These degradation products suggested dehydrochlorination as the main degradation pathway of δ-HCH by iron sulfide. Different kinetic experiments indicate that the rate constants (ka) during dechlorination of δ-HCH by iron sulfide rose with pH: 0.003 d-1 (pH 5.8) < 0.034 d-1 (pH 8) < 0.085 (pH 9.3) < 0.286 d-1 (pH 9.6). Upon Rayleigh model calculations, an enrichment factor (εC) of -7.8 ± 1.0 ‰ was calculated for δ-HCH dehalogenation by FeS at pH 8.0. This suggests an apparent kinetic isotope effect (AKIEC) value of 1.049 ± 0.006 for dehydrohalogenation. The magnitude of the isotope effect from this paper furthermore supports dehydrohalogenation and opens the possibility to study the degradation of HCHs by iron (II) minerals containing FeS as mackinawite in oxygen-deprived environments.

Magmatic differentiation of peralkaline granites: Constraints from iron isotope fractionation between Fe-bearing minerals

Iron isotopes have been found useful in tracing magmatic processes of calc-alkaline granitic magmas, but its application in peralkaline granitic systems is hampered by the lack of information regarding the Fe isotope fractionation factors between alkali-rich ferromagnesian silicate minerals and FeTi oxides. To better understand the behavior of Fe isotopes during peralkaline magma differentiation, we carried out high-precision Fe isotope analyses on peralkaline and associated metaluminous high-silica granite rocks and Fe-bearing minerals separated from the rocks in Zhoushan archipelago, southeast China. The Fe-bearing mineral show a large dispersion in Fe isotope compositions, with δ56Fe ranging from 0.03 ‰ to 0.70 ‰, following the sequence of K-feldspar ≥ magnetite > aegirine > arfvedsonite > ilmenite. The δ56Fe differences between the mineral pairs are relatively consistent. Based on the magmatic temperatures defined by quartz-zircon oxygen isotopic geothermometer, the temperature-dependent equilibrium Fe isotope fractionation functions between following mineral pairs are obtained: Δ56Feaegirine-arfvedsonite = 0.20 (± 0.07) × 106/T2, Δ56Femagnetite-arfvedsonite = 0.38 (± 0.06) × 106/T2, and Δ56Femagnetite-aegirine = 0.16 (± 0.04) × 106/T2. The bulk peralkaline granites have variable but generally high δ56Fe values ranging from 0.28 ± 0.03 ‰ to 0.62 ± 0.04 ‰, with a mean of 0.42 ± 0.09 ‰ (1SD), which are higher than those of the associated metaluminous granitic samples (δ56Fe = 0.22 ± 0.05 ‰, 1SD). Furthermore, δ56Fe values of the peralkaline granites are negatively correlated with Sm/Yb and MnO, consistent with removal of isotopically light Fe-enriched arfvedsonite, implying that peralkaline granites experienced extensive magma differentiation regardless whether they were derived from differentiation of mantle-derived basaltic melts or partial melting of curst sources. Our results highlight a large Fe isotope fractionation between alkali ferromagnesian silicates and oxides, confirming Fe isotopes as a potential tool in tracking the differentiation processes of peralkaline magmas.

The cobalt and nickel enrichment in base metal sulfides from the Xiarihamu Cu-Ni-Co deposit, China: Constrained by in-situ mineral geochemistry of sulfides

Rapidly growing demand for cobalt and nickel in rechargeable battery industry promotes research on metallogenic theory of magmatic Cu-Ni-Co sulfide deposits. Xiarihamu Cu-Ni-Co deposit, one of the lately discovered Co-rich magmatic sulfide deposits in China, is typical of distribution in orogenic belts, rather than in divergent tectonic settings as many deposits of the same type. In-situ elemental and sulfur isotopic analyses of base metal sulfides (BMS; pyrrhotite, pentlandite, and chalcopyrite) from Xiarihamu were conducted in this study. The strongly negative correlation between Fe and Co + Ni reveals the major occurrence of Co and Ni as isomorphism states in pentlandite and pyrrhotite. The δ34S values of pentlandite and pyrrhotite generally increase with Co contents and Co/Ni ratios, indicating that the Co enrichment within BMS accompanied with enhanced contamination of crustal sulfur. Zinc, Cd, Sb, and Te are significantly and preferentially fractionated into intermediate sulfide solution (ISS) from which chalcopyrite exsolved. The Se contents and Se/S ratios of pentlandite and pyrrhotite in lherzolite/harzburgite are much higher than those of BMS from gabbro, which has systematically higher δ34S values. Combined with the partially overlapped Sb/Se and As/Se ratios of BMS from lherzolite and gabbro, as well as similar calculated R factors of ore-hosting peridotite and gabbro, it is proposed that the studied Xiarihamu gabbro was crystallized from a separate pulse of Co-Ni-enriched, Se-depleted and intensively contaminated mafic parent magma, rather than evolved from ultramafic magma through crystallization fractionation. The lack of olivine and spinel in gabbro also promoted more Co and Ni into sulfide liquid. Based on Se/Te ratios, the pentlandite and pyrrhotite from drill core XH1E01S was originated from sulfide liquid, which suffered higher degree of crystallization fractionation of monosulfide solution (MSS). While pentlandite and pyrrhotite that crystallized from less evolved parent sulfide liquid bear less cobalt, such as those collected from drill core XH1109. This study strengthens the potential importance of crustal contamination and crystallization fractionation of MSS from sulfide liquid during Co enrichment within BMS (pentlandite and pyrrhotite).

Petroleum evolution and its genetic relationship with the associated Jinding Pb[sbnd]Zn deposit in Lanping Basin, Southwest China

The spatial association of hydrocarbons with metalliferous ore deposits is found worldwide and is particularly common to MVT PbZn deposits. Heavy oil and bitumen are found in the Jinding PbZn deposit within the Lanping Basin, South China. However, the temporal and genetic associations between hydrocarbons and the deposit are still controversial. To this end, integrating Raman analysis, ReOs geochronology and transmission electron microscopy analysis of the bitumen and in situ S isotope analyses of the sulfide, the petroleum evolution of the Jinding reservoir and its genetic relationship with the PbZn deposits were discussed. Bitumen ReOs data from this study and published works indicate that the late Triassic shales underwent two distinct oil-generation events before mineralisation (~25 Ma), with initial oil generation occurring during the early Cretaceous (~116 Ma) and the second during the early Paleogene (ca. 68–59 Ma). These two ages agree with the modelled thermal history of the Jinding reservoir. Combining the oil-before-ore timing sequence, high metal abundance of the bitumen, two negative sulfur isotope peaks of the sulfide and high S/C atomic ratio of the bitumen from the Jinding deposit, the oil-containing aqueous solutions were considered as one metal carrier during the hydrocarbon migration and accumulation; further, bacterial sulfate reduction and thermo-chemically induced sulfate reduction processes could have participated in the supply of reduced sulfur for the PbZn deposit precipitation.

Enhancing biodiversity: historical ecology and biogeography of the Santa Catalina Island ground squirrel, Otospermophilus beecheyi nesioticus.

People have influenced Earth's biodiversity for millennia, including numerous introductions of domestic and wild species to islands. Here, we explore the origins and ecology of the Santa Catalina Island ground squirrel (SCIGS; Otospermophilus beecheyi nesioticus), one of only five endemic terrestrial mammals found on California's Santa Catalina Island. We synthesized all records of archaeological/palaeontological SCIGS, conducted radiocarbon dating and stable isotope analysis of the potentially earliest SCIGS remains and performed genetic analysis of modern SCIGS. Squirrels were not identified in island palaeontological deposits, but at least 12 island archaeological sites contain SCIGS bones, including some that are butchered or burned. All directly dated SCIGS bones are Late Holocene in age and younger than approximately 1290 cal BP. The first mitochondrial genome for modern Otospermophilus beecheyi and 15 modern SCIGS mitogenomes document at least one introduction of squirrels. Stable isotope data indicate variable SCIGS diets and potential subsidies from marine environments to terrestrial plants consumed by some individuals. We cannot rule out a natural overwater dispersal, but the earliest SCIGS remains post-date the earliest evidence for people by several millennia and, along with other lines of evidence, support a human-assisted translocation of squirrels during the Late Holocene. These data illustrate the important role of Indigenous people in shaping and enhancing island biodiversity and ecology around the world.

Sources of Silver in North-Eastern Rus in the 10th–13th centuries ad according to lead isotope analysis

The article discusses the results of lead isotope analysis of 54 silver objects from the 9th–13th centuries AD from rural sites of Suzdal Opolye and villages around Murom. As a result of comparing the obtained data with the available databases for Pb-Pb isotopic values of archaeological objects from various collections and ore samples, it was established that in the second half of the 10th – early 11th century AD, Samanid dirhams were used in Opolye as a raw material for jewellery making. In the 11th century, silver from European sources began to flow into the region via the Baltic, becoming dominant by the end of the century. In Opolye and Murom of the 12th century, adornments were made from European raw materials.

Giant plagioclase in the Steens Basalt, southeast Oregon, USA: Tracking the balance of differentiation processes in continental flood basalt evolution

Giant plagioclase basalts (GPBs), flows that contain abundant and conspicuous plagioclase crystals ≥1 cm in length, exist at many continental flood basalt provinces, and their presence can provide a window into the crustal differentiation processes and storage conditions that produced the magmas prior to eruption. GPB flows occur in the Steens Basalt of southeast Oregon, USA, one of the earliest members of the Columbia River Flood Basalt Group, but their origin in this province has not been studied in detail. We conducted quantitative textural analysis utilizing crystal size distributions (CSDs) at the outcrop and thin section scale, as well as in situ plagioclase trace element and isotopic compositional analysis, in order to elucidate the processes responsible for generating two end-member textural types of GPB found in the Steens Basalt: daisy stone glomerocryst clusters composed of radiating plagioclase laths and single isolated plagioclase. CSD patterns suggest a changing balance of multiple differentiation processes affected the magmas that created each GPB textural type. In the daisy stone plagioclase, crystals rarely exhibit resorption textures, trace element abundances are comparatively low with minimal variability, and Sr isotopes are commonly in equilibrium with groundmass. In the single isolated plagioclase, resorption textures are common, trace element abundances are generally higher and display within crystal variation, and Sr isotopes are typically not in equilibrium with groundmass. These distinctive characteristics require separate mechanisms to generate each end-member GPB texture. Daisy stone GPBs form by growth of large crystals following mafic recharge events that completely resorb entrained cumulate plagioclase. A large amount of plagioclase may then grow with minimal cooling following recharge due to saturation in plagioclase components. In contrast, single isolated GPBs are the result of partial resorption of both entrained and resident plagioclase following less voluminous and less primitive recharge events; regrowth then occurs on the partially resorbed cores when cooling resumes. Both GPB types are formed by thermal cycling, but each texture reflects the differentiation processes that were prevalent during different eruptive stages of the Steens Basalt, as the balance between recharge, crystal fractionation, and assimilation varied in time.

Stable isotope analysis of faunal remains from Bronze Age Kaymakçı, Western Anatolia

This paper presents the results of stable carbon ( δ13C) and nitrogen ( δ15N) isotopic analysis of bulk bone collagen from faunal remains from the Bronze Age site of Kaymakçı in western Anatolia. We use the isotopic values in conjunction with zooarchaeological data and contextual archaeological information to examine human-environment interactions; in particular, animal management and husbandry. Middle and Late Bronze Age agricultural systems in western and central Anatolia remain poorly understood, and this research aims to contribute to rectifying this research gap. We obtained stable isotopic values from both wild and domestic species, including deer, hare, birds, catfish, dogs, pigs, caprids and cattle. The δ13C values range from −22.0‰ to −16.9‰ and the δ15N values range from 2.3‰ to 10.3‰. For cattle, the δ13C values suggest that some specimens were subject to different management strategies, likely related to feeding or herding patterns or even the movement of animals in and around the region through some exchange mechanism. There appears to be no fixed location or strategy for the management of caprids and, furthermore, there is evidence to suggest that the herding/management areas of some caprids overlapped with those of wild animals such as deer and hare. Variation in δ15N values for pigs may indicate that whilst some animals in the sampled assemblage were free-roaming, others were penned. For the pigs and some other herbivorous domesticated species variation in δ15N values may also point to the exploitation of the wetland areas around Lake Marmara.

Substantial in situ Ti isotope variations in rutile record source and fluid evolution of porphyry copper mineralization systems

Titanium (Ti) and its stable isotopes have been widely used as tracers for magmatic processes. However, our understanding of Ti isotope behavior in magmatic-hydrothermal systems remains limited. Hence, the in situ Ti isotope composition (δ49Ti) of magmatic titanite and hydrothermal rutile associated with magnetite and chalcopyrite mineralization was determined for the first time in four well-characterized porphyry copper deposits in southern Tibet. The rutile formed through the alteration of primary Ti-rich minerals during fluid-rock interaction in the early high-temperature magnetite and later moderate-temperature chalcopyrite stages of mineralization. Hydrothermal rutile, altered from magmatic titanite, exhibits δ49Ti values similar to those of residual magmatic titanite. This suggests that hydrothermal rutile inherited the Ti isotope composition of magmatic titanite. The average δ49Ti values of rutile are negatively correlated with whole-rock εNd(t) and zircon εHf(t) data, and positively correlated with whole-rock (87Sr/86Sr)i values, which suggests that the initial Ti isotope compositions of hydrothermal rutile in porphyry copper deposits primarily reflect their source. Rutile from the Qulong deposit sometimes exhibits fractionation of δ49Ti at levels exceeding 0.5‰, displaying a negative correlation with Zr and FeO, which may be attributed to the formation of magnetite and rutile at an early potassic alteration stage. Isotopically light Ti is preferentially incorporated into magnetite and rutile. Thus, the rutile associated with sulfide mineralization that formed from the remaining fluids during a later stage of phyllic alteration is enriched in heavy δ49Ti. These findings contribute to the understanding of how rutile fractionates Ti isotopes in hydrothermal systems related to porphyry copper deposits. In local contexts, the substantial crystallization of magnetite, along with the preferential incorporation of isotopically light Ti during the early stages, leads to a decrease in oxygen fugacity within the ore-bearing fluid. This, in turn, facilitates the formation of sulfides during later stages. The results of this study demonstrate the efficacy of in situ Ti isotope analysis as a powerful tool for tracking fluid and metal sources, and can be used to help interpret ore precipitation throughout different stages of magmatic-to-hydrothermal ore-forming processes.

The interplay of resource availability and parent foraging strategies on juvenile sparrow individual specialization

Temporal variation in resource availability, amplified by global change, may have strong impacts on species breeding at temperate and high latitudes that cue their reproduction to exploit seasonal resource pulses. This study examines how resource availability and parental care influence niche partitioning between and within age classes in the rufous‐collared sparrow, which provides extensive parental care. We hypothesized juveniles would exhibit narrower niches focused on high‐quality resources compared to adults, regardless of resource availability. We used stable isotope analysis to quantify individual and population niches in juveniles and adults across the breeding season in two cohorts experiencing contrasting resource landscapes. Contrary to our initial hypothesis, juveniles exhibited greater among‐individual diet variation and smaller total niche widths (i.e. higher levels of individual specialization, IS) during periods of high food availability in comparison to periods of food scarcity. Interestingly, total niche width and IS of adults remained stable across seasons despite a shift in trophic level, highlighting their potential role in providing a consistent diet for their young. These findings reveal a dynamic interplay between resource availability, parental care, and IS, with important implications for understanding population resilience under variable resource scenarios. The study also suggests that adult sparrows modify their provisioning strategies based on resources, potentially buffering offspring from environmental fluctuations. Understanding age‐specific responses to resource variation is crucial for predicting species responses to ecological conditions, particularly in regions like central Chile where seasonal resource limitation is expected to become more variable in response to climate change.

Recommendations for stable isotope analysis of charred archaeological crop remains

Stable isotope analysis of plant remains recovered from archaeological sites is becoming more routine. There remains a lack of consensus, however, on how to appropriately select archaeological plant remains for isotopic analysis, how to account for differences in preservation and the effect of potential contamination, and how to interpret the measured isotope values in terms of the conditions in which the plants grew. In this paper, we outline the main issues to be considered when planning and conducting an isotopic study of archaeobotanical remains. These include: (1) setting out the research question(s) that will be answerable using available analytical approaches, (2) considering the archaeological context from which plant remains derive, (3) determining appropriate sample size through consideration of estimate precision, (4) establishing the conditions in which plant remains have been preserved and potential effects on their isotope values, and (5) accounting for possible contamination during deposition. With these issues in mind, we propose some recommendations for researchers to consider when planning and conducting an isotopic study of archaeobotanical remains.

Specifying groundwater recharge zones through hydrogeochemical and isotopic analyses in a multilayer volcanic aquifer: a case study in the Yogyakarta-Sleman Groundwater Basin, Indonesia

Specifying groundwater recharge zones through hydrogeochemical and isotopic analyses in a multilayer volcanic aquifer: a case study in the Yogyakarta-Sleman Groundwater Basin, Indonesia

Stable isotope of Mesolithic remains of Pila wernei of the Nile area, Sudan: A tool for palaeoenvironment reconstruction

The article deals with stable isotopes of oxygen and carbon on current and archaeological semi-aquatic gastropod shell of the Pila wernei from Sudan and reports some new 14C analyses on archaeological Pila specimens. This, with the aim of obtaining new information on climatic and environmental changes in the al-Khiday area during the first phase of Holocene. The Pila shells come from a well-preserved shell midden present at al-Khiday and dated 8700-7000 cal yr BP. The area of al-Khiday was inhabited since at least 10 ka. Pila wernei species has never been studied in detail; this study demonstrates that the O and C isotope composition of aragonite shell is able to record the environmental and diet changes during the gastropod life. The comparison between the isotope data obtained on present-day and archaeological shells show a prevalence of C4 plants and higher rainfall during the Mesolithic. Two climatic fluctuations have been recognised: the first one indicating wetter conditions from 8650-8400 to 8500-8050 cal yr BP (decrease of the δ18O values), the second one pointing less wetter conditions from 8500-8050 to 7850-7600 cal yr BP (increase of δ18O values). Despite the difficulties in studying semi-aquatic gastropods due to their lifestyle habit, the identification of climatic fluctuations in the Early Holocene confirms the reliability of this proxy for climatic reconstructions. Despite the high number of isotopic analyses (1556) used in this work, they were not sufficient to mirror the fast climate changes characterising the studied period and finally obtain a detailed reconstruction for nearly the two millennia considered. Nonetheless, future projects may benefit greatly from unveiling the shell-environment relationship of the species.

Iron isotopes of Chang'e-5 soil and mineral components: Implications for post-eruption processes on lunar surface

Due to rapid magma cooling and extensive space weathering, significant disequilibrium crystallization and secondary modification widely occur in lunar mare basalt after its eruption on the lunar surface. In this study, we conducted bulk and in-situ Fe isotope analyses to investigate the post-eruption processes on Chang'e-5 (CE-5) samples. The CE-5 soil shows a minor elevation of δ56Fe value (∼0.05 ‰) relative to the CE-5 basalt clasts. Correlations between Ni and Cu contents with δ56Fe values suggest that the minor increase in the δ56Fe from the CE-5 basalt to soil primarily occurred during evaporation caused by meteorite impacts. Such isotopic variation between CE-5 basalt and soils is notably lower than what is observed for Apollo samples and reflects the low maturity of CE-5 soils. This is consistent with the low Is/FeO value constrained by magnetic approaches. Therefore, measuring the δ56Fe values of lunar soil is suitable to evaluate the degrees of maturity for lunar soils due to space weathering. In-situ analyses of δ56Fe reveal significant variations in different grains of olivine (δ56Fe: −0.57 to −0.17 ‰) and ilmenite (−0.06 to +0.42 ‰) and also in their interior (mainly for olivine). These δ56Fe variations in minerals can be ascribed to the disequilibrium crystallization of lava flow and fast cooling, which is consistent with conclusions based on petrologic observations such as its extensive differentiation and silicate liquid immiscibility. Therefore, the post-eruption processes on the lunar surface could lead to significant variations in isotopic compositions at different scales of basalts, which in turn record the history of late-stage magma evolution and space weathering on the lunar surface.

A conceptual and numerical model of fluid flow and heat transport in the Topusko hydrothermal system

Comprehensive understanding of hydrothermal systems is often obtained through the integration of conceptual and numerical modelling. This integrated approach provides a structured framework for the reconstruction and quantification of fluid dynamics in the reservoir, thereby facilitating informed decision-making for sustainable utilisation and environmental protection of the hydrothermal system. In this study, an updated conceptual model of the Topusko hydrothermal system (THS; central Croatia) is proposed based on structural, geochemical, and hydrogeological analyses. The stratigraphic sequence and the structural framework of the THS were defined based on geological maps and field investigations. As depicted by hydrochemical and isotope analyses, thermal waters in Topusko (temperatures of up to 65 °C) are of meteoric origin and circulate in a carbonate aquifer. The THS receives diffuse recharge approximately 13 km S from Topusko, where Triassic carbonates crop out. Gravity-driven regional groundwater circulation is favoured by regional thrusts that tectonically uplifted Palaeozoic low permeable rocks. These structures confine the fluid flow in the permeable, fractured and karstified, Triassic carbonates favouring the northward circulation of the water. A regional anticline lifts the aquifer closer to the surface in Topusko. Open fractures in the anticline hinge zone increase the fracturing and permeability field of the aquifer promoting the quick upwelling of the thermal water resulting in the Topusko thermal springs. Numerical simulations of fluid flow and heat transport corroborate the proposed conceptual model. In particular, a thermal anomaly was modelled in the Topusko subsurface with temperature values of 31.3 °C and 59.5 °C at the surface and at the base of the thermal aquifer, respectively, approaching the field observations. These findings showed that the circulation of Topusko thermal water is influenced by regional and local geological structures suggesting that the enhanced permeability field in the discharge area enables the formation of the natural thermal springs.

Trophic Position Stability of Benthic Organisms in a Changing Food Web of an Arctic Fjord Under the Pressure of an Invasive Predatory Snow Crab, Chionoecetes opilio

The introduction of a large predatory snow crab, Chionoecetes opilio, into the Kara Sea is a unique situation where the impact of an invasive species affecting an otherwise undisturbed ecosystem can be observed unhindered by other ecosystem stressors. Trophic interactions are one of the principal relationships between animals and can help assess an ecosystem’s stability. The trophic positions and sources of organic material for the most common benthic species of Blagopoluchiya Bay sampled at different stages of the invasion were calculated using stable isotope analysis. The most pronounced changes in the trophic web occurred amongst the megabenthic species, where previously most abundant deposit-feeding ophiuroids have disappeared. However, the benthic species’ trophic position and primary production source preference did not change. A sea star, Urasterias lincki, remained the highest carnivore in the bay, and the invasive crab remained at a lower trophic level, showing higher omnivory in its diet. Any changes in the consumers’ prey items were within the same trophic level. Overall, active predators became one of the most abundant feeding mode groups. The average weighted trophic position of all megabenthic species increased to the third trophic level, where mostly secondary consumers remained.

A life course study of the Beixin culture residents from the Neolithic site of Xiaheqiadong, Shandong Province, China

AbstractThe Xiaheqiadong site located in Zhangqiu district, Jinan city, Shandong province, China, was excavated in 2016 by the Jinan Institute of Archaeology, which revealed six single burials dating to the Beixin culture period (ca. 5,300–4,500 BC to ca. 4,100–3,600 BC). This paper used bioarchaeological methods to study the human skeletal remains to reconstruct the life course of the residents of the Beixin culture at the Xiaheqiadong site, focusing on stable isotope analysis, evaluation of stress, tooth ablation, and intentional skull modification. Based on stable isotope analysis of carbon, it is evident that the dietary structure of the ancient residents of Xiaheqiadong was mainly dependent on C4 plants or animals that ate mainly C4 plants. The stable isotope analysis of nitrogen indicated that the ancient residents of the Xiaheqiadong site exhibited a relatively sufficient consumption of animal protein. Furthermore, this result also reveals that a subsistence economic model was established consisting of farming, gathering, and hunting. Observations of the stress indicators (including cribra orbitalia, porotic hyperostosis, and linear enamel hypoplasia) revealed that they experienced poor health conditions and were under high levels of stress during infancy and early childhood. However, this situation improved with increasing age, suggesting that residents from the Xiaheqiadong site had the capacity to withstand severe living conditions and adapt after experiencing stress events. The tooth ablation and occipital modification cases from the Xiaheqiadong site are the earliest cases among the individuals with accurate dating results found in China.

Exploring hydrogen isotope fractionation in lipid biomolecules of freshwater algae: implications for ecological and paleoenvironmental studies

ABSTRACT Understanding the stable hydrogen isotope (δ 2H) composition and fractionation in lipid biomolecules of primary producers, such as terrestrial and aquatic plants, is crucial for deciphering past environmental conditions, as well as applying compound-specific stable isotope analysis for the study of metabolic and ecological processes. We conducted a new tracer experiment to explore the δ 2H composition of algal fatty acid biomarkers, focusing on freshwater algae, which form the base of aquatic food webs. We selected a range of algal species widely found in freshwater ecosystems and cultivated them under controlled conditions. First, we added 2H2O to ambient water as a tracer to investigate the net hydrogen isotope fractionation during algal lipid synthesis at isotopic equilibrium, which is particularly informative for paleo-geochemical studies. Then, we conducted kinetic experiments to quantify the time needed for algal fatty acids to achieve isotopic steady-state conditions in response to the change in ambient water δ 2H values. Our findings revealed substantial variability in hydrogen isotope fractionation among different algal taxa and various fatty acids. Based on taxa, different fatty acids exhibited faster integration of water hydrogen than others, but they were not necessarily in the order of the biosynthetic pathway. This experiment underscores the complexity of hydrogen isotope fractionation and the requirement for controlled laboratory studies to properly apply compound-specific stable H isotope analysis techniques in ecological and paleo-environmental studies.

Authenticating the Geographical Origin of Jingbai Pear in Northern China by Multiple Stable Isotope and Elemental Analysis

The Jingbai pear is one of the best pear species in China with high quality and nutrition values which are closely linked to its geographical origin. With the purpose of discriminating the PGI Mentougou Jingbai pear from three other producing regions, the stable isotope ratios and elemental profiles of the pears (n = 52) and the corresponding soils and groundwater were determined using isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results revealed that δ15N, δ18OJ, and Li were significantly different (p &lt; 0.05) in samples from different regions, which indicated their potential to be used in the geographical origin classification of the Jingbai pear. The nitrogen isotopic values of the pear pulp were positively correlated with the δ15N value and nitrogen content of the corresponding soils, whilst the B, Na, K, Cr, and Cd contents of the pear pulps were positively correlated with their corresponding soils. Orthogonal partial least squares discriminant analysis (OPLS-DA) was performed in combination with analysis of the stable isotopes and elemental profiles, making it possible to distinguish the cultivation regions from each other with a high prediction accuracy (a correct classification rate of 92.3%). The results of this study highlight the potential of stable isotope ratios and elemental profiles to trace the geographical origin of pears at a small spatial scale.

A multidisciplinary approach to forensic biological profiling on a single tooth and nail sample.

Analysis of a single tooth and nail can provide valuable forensic information, including year of birth, year of death, age, sex, DNA-profile, geographic residence during childhood and at time of death and drug exposure. The aim is to minimize the amount of used bodily material and to validate the applicability of a multidisciplinary sampling protocol. A nail of the big toe, a tooth and blood of seven deceased individuals were collected postmortem. Collected materials were sampled and segmented in accordance with the multidisciplinary sampling protocol. DNA analysis was conducted on the pulp of the tooth, isotope analysis (Sr, Pb, O and C) on the enamel and 14C-, toxicological and tooth cementum annulation analysis on root segments. DNA-, isotope (Sr, Pb, O and C) -, toxicological-, and 14C -analysis were conducted on toenail segments. The acquired DNA profiles were compared with profiles acquired from blood. Material from seven deceased persons was analysed. 45 out of 56 analyses on dental samples were successful, constituting a success rate of 80%. Additionally, 27 out of 35 analyses were successful on nail samples, yielding a success rate of 77%. DNA-, toxicological and 14C- analyses performed better in nail than in tooth. Isotope analyses performed better in tooth than in nail. A profile with personal characteristics was constructed and matched for 62% of parameters with collected medical information. The performed sampling protocol for simultaneous multidisciplinary forensic analysis on a single tooth and nail sample provided applicable results and valuable information.