Stable Isotope Studies Research Articles

Redox-controlled antimony isotope fractionation in the epithermal system: New insights from a multiple metal stable isotopic combination study of the Zhaxikang Sb–Pb–Zn–Ag deposit in Southern Tibet

Redox reactions, biological processes, evaporation and precipitation processes, adsorption, and Rayleigh distillation mechanisms have been proposed to account for the fractionation of antimony (Sb) isotopes in natural materials. However, only one paper was published to support and characterize the Rayleigh distillation induced Sb isotopic fractionation in a hydrothermal system. Therefore, the Sb isotopic fractionation mechanism research in the epithermal system is still negligible, which severely restricts future application. The Zhaxikang Sb–Pb–Zn–Ag deposit is the only super-large deposit within the North Himalayan Metallogenic Belt (NHMB), which comprises two episodes of mineralization (First episode: Pb–Zn mineralization, Stages 1 and 2; Second episode: Sb mineralization, Stages 3 to 6). Herein, we measured the δ123SbNIST 3102A values of stage 4 sulfosalt minerals and stage 5 stibnite from the Zhaxikang Sb–Pb–Zn–Ag deposit, to resolve the fractionation direction and relative magnitude of Sb isotopes caused by these aforesaid geologically prominent mechanisms in the epithermal systems with an auxiliary investigation of Fe–Cu isotopes. The second episode of Sb-containing hydrothermal fluid has leached metals (e.g., Pb, Ag, Fe, Cu) from pre-existing Pb–Zn orebodies, to initiate the formation of stage 4 sulfosalt minerals. According to XPS (X-ray Photoelectron Spectroscopy) analyses, the Cu isotopic variation of stage 4 bournonite (0.08‰ – 0.89‰) must be controlled primarily by the reduction reaction (Cu2+ + e− → Cu+) during leaching and precipitation. Keeping in mind a good linear correlation between δ123Sb and δ65Cu values (R2 = 0.99) for bournonite, the same mechanism was used to decipher the variation in δ123Sb values (0.10‰ – 0.48‰) of bournonite (Sb5+ + 2e− → Sb3+). Abundant native sulfur within the orefield allowed for the overall reaction equation of CuFeS2 + FeS2 + PbS + Sb5+(aq) = CuPbSbS3 + Fe2+(aq) + 2S to describe the bournonite formation. Accordingly, the Sb isotopic variations (−0.27‰ to 0.48‰) of Sb-bearing minerals (boulangerite, bournonite and stibnite) were empirically attributed to redox reactions. The Rayleigh distillation model indicated that the observed fractionation was most likely induced by redox reactions, while the related theoretical calculations revealed a great antimony exploration potential in deeper parts of the orefield. Overall, the Sb isotopes could be used to identify redox changes in the epithermal system, and exhibit great potential in tracing metal sources, monitoring fluid evolution and ore formation, and providing insights into mineral exploration.

Stable isotopes in the snow of the coastal areas of Antarctica

The first results of study of stable isotopes of oxygen (δ18O) and hydrogen (δD) in the snow samples taken on the islands of Marguerite Bay (Antarctic Peninsula), in the Vecherny Oasis (Enderby Land), and Larsemann Hills (Princess Elizabeth Land) by the participants of the 12th Belarusian Antarctic Expedition (January–March 2020) are presented. The concentration of water isotopes: deuterium (D) and oxygen-18 (18O) in the samples was determined using a laser isotope composition analyzer Picarro L2130. A total of 32 snow samples were analyzed. The statistical parameters of the isotopic composition of snow were estimated, and the main differences in the content of δ18O and δD between the study areas were shown. A decrease in the content of heavy oxygen and hydrogen isotopes in the newly fallen snow to the old snow of the surface horizons is shown. The maximum values of δ18O and δD are typical for the Maritime Antarctica, decreasing towards the coastal zone and further – towards its continental part. The possible factors affecting the isotope content are described. It is shown that the monitoring of the isotope composition can be an integral part of the monitoring of climatic changes within the area of operation of the Belarusian Antarctic Expedition. The study of the isotopic composition of surface snow is important for the reconstruction of the paleoclimate of the marginal zone of the Antarctic ice sheet based on the ice cores study.

Carbon and oxygen isotopic composition of fluid inclusion CO2 and CH4 within the Archean Junction gold deposit, Kambalda, Western Australia

ABSTRACT The Junction orogenic gold deposit in the St Ives district of Western Australia is characterized by a syn-gold mineral assemblage dominated by quartz-calcite-albite-biotite-chlorite-pyrrhotite. The deposit had a light hydrocarbon,CO2, and O2 soil-gas signature above known mineralization prior to mining and it has been proposed that the source of the light hydrocarbon gases in the soil was gas-rich fluid inclusions trapped in gold-related alteration minerals, particularly calcite, albite, quartz, and pyrrhotite. Linking the soil gases with those in the deposit is extremely difficult. However, establishing that the gases in the soil are indeed present within the deposit and that those gases are related to the syn-Au alteration minerals is achievable through stable-isotope studies. Carbon and O stable-isotope compositions of pre-gold, syn-gold, and post-gold quartz veins; syn-gold and post-gold calcite; and CO2 and CH4 in the fluid inclusions that each of these minerals host were investigated to establish if the various mineral and fluid-gas species in the deposit are in isotopic equilibrium with each other, an important first step to relate syn-ore minerals with the relevant gases. Pre-ore Mo-type quartz veins contain CO2 (δ13Cgas = –1‰) and CH4 (δ13Cgas = ca. –33‰) in fluid inclusions at a ratio of ca. 93:7. The paucity of Mo-type quartz veins in the deposit suggests that these veins were not the main source of the soil-gas signature. Syn-gold alteration post-dates the Mo-type quartz veins. Quartz and co-existing calcite in the Au-bearing Junction shear zone have δ18Omineral values around 12.0 and 10.5‰, respectively. Multiple co-existing quartz-calcite pairs indicate that gold deposition occurred at ∼400 °C. This temperature agrees with mineral equilibria temperature estimates, the entrapment temperatures of fluid inclusions, and temperature modelling of solid-solution mineral phases. The temperature dictates that the quartz and calcite are in isotopic equilibrium with each other. The calcite in the Junction shear zone has δ13Cmineral values from –7.4 to –2.5‰, indicating that the CO2-rich ore fluid had a δ13Cfluid value of –3.7 ± 0.9‰. CO2 and CH4 released from quartz-hosted fluid inclusions have δ13Cgas values from –4.3 to +3.5‰ (mean = –1.5 ± 1.9‰) and –50.5 to –35.2‰, respectively. The isotopic composition of the fluid inclusion CO2 is in disequilibrium with co-existing CH4 that was co-released from the same quartz vein and the calculated δ13Cfluid value from co-existing calcite. Isotopic mass balance calculations using the two co-released gases show that the CO2 was initially in equilibrium with the syn-ore calcite but has since re-equilibrated with CH4 at temperatures below 200 °C. The abundance of CH4 in some quartz veins suggests that the syn-gold vein assemblage could be the source for the soil-gas anomaly. Post-gold veins contain quartz and calcite that have δ18Omineral values of ca. 11.0 and 10.0‰, respectively. Individual mineral pairs indicate precipitation at ∼320 °C from a fluid with a δ18Ofluid value of 4.7 ± 0.9‰, distinct from that which formed the syn-gold quartz veins. The post-gold calcite has δ13Ccalcite values from –7.5 to –5.4‰, indicative of formation from a CO2-bearing fluid having a δ13Cfluid value of –4.6 ± 0.9‰. The δ13Cfluid values are indistinguishable from fluid inclusion CO2 values of –3.6 ± 0.9‰, indicating no post entrapment re-equilibration, which suggests that CH4 was at trace volumes or absent in the post-gold quartz veins. These data lead to the conclusion that post-entrapment reequilibration between fluid inclusion CO2 and CH4 has occurred, but that the two gases were likely in equilibrium at the time of entrapment. This has implications for the interpretation of C isotope studies that focus on fluid inclusion CO2 measured from other gold and base-metal deposits, especially when the isotopic value of that CO2 is assumed to represent a specific source for the ore-forming fluids. The data also lead to a model that proposes that the syn-gold alteration assemblage could have produced the soil-gas anomalies observed above the mineralization.

Tea Consumption Reduces Iron Bioavailability from NaFeEDTA in Nonanemic Women and Women with Iron Deficiency Anemia: Stable Iron Isotope Studies in Morocco

BackgroundAvailable data suggest that polyphenols from tea can inhibit iron absorption from ferric sodium EDTA (NaFeEDTA), but previous studies were done in small groups of mostly nonanemic adults. Morocco recently introduced national wheat flour fortification with NaFeEDTA, but tea is the national beverage and is consumed with most meals. ObjectivesOur objective was to quantify bioavailability of iron from NaFeEDTA when added to a wheat flour–based meal in both nonanemic women and women with iron deficiency anemia (IDA), when consumed with and without traditional Moroccan green tea. MethodsWe recruited 2 groups of healthy Moroccan women (n = 46): women with IDA (n = 25; hemoglobin <12 g/dL, serum ferritin <15 μg/L) and nonanemic women (n = 21). Each group received in random order 2 standardized test meals containing 6 mg Fe as isotopically labeled NaFeEDTA and either 300 mL of tea or water. Fractional iron absorption (FIA) was measured by the erythrocyte incorporation of stable iron isotopes after 14 d. We performed linear mixed-model analysis and post hoc sample t tests to assess the effects of group and tea on FIA. ResultsThe polyphenol content of the tea serving was 492 mg. Tea consumption reduced iron absorption from NaFeEDTA by >85% in both IDA and nonanemic women. There were group (P < 0.001) and tea (P < 0.001) effects on FIA, but no group by tea interaction (P = 0.312). Median (IQR) FIA (%) in women with IDA from test meals consumed without and with tea was 36.7 (24.2–39.8) and 4.1 (2.8–6.1), respectively (P < 0.001). Median (IQR) FIA (%) in nonanemic women from test meals consumed without and with tea was 16.7 (9.2–24.2) and 1.4 (0.8–2.9), respectively (P < 0.001). ConclusionsFIA from wheat flour–based meals without and with tea was ∼2-fold higher in women with IDA than in nonanemic women. Providing fortificant iron as NaFeEDTA cannot overcome the inhibition of tea polyphenols on iron absorption, even in IDA, where iron absorption is strongly upregulated. This trial was registered at www.clinicaltrials.gov as NCT02175888.

Nitric Oxide Deficiency in Mitochondrial Disorders: The Utility of Arginine and Citrulline.

Mitochondrial diseases represent a growing list of clinically heterogeneous disorders that are associated with dysfunctional mitochondria and multisystemic manifestations. In spite of a better understanding of the underlying pathophysiological basis of mitochondrial disorders, treatment options remain limited. Over the past two decades, there is growing evidence that patients with mitochondrial disorders have nitric oxide (NO) deficiency due to the limited availability of NO substrates, arginine and citrulline; decreased activity of nitric oxide synthase (NOS); and NO sequestration. Studies evaluating the use of arginine in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) presenting with stroke-like episodes showed symptomatic improvement after acute administration as well as a reduction in the frequency and severity of stroke-like episodes following chronic use. Citrulline, another NO precursor, was shown through stable isotope studies to result in a greater increase in NO synthesis. Recent studies showed a positive response of arginine and citrulline in other mitochondrial disorders besides MELAS. Randomized-controlled studies with a larger number of patients are warranted to better understand the role of NO deficiency in mitochondrial disorders and the efficacy of NO precursors as treatment modalities in these disorders.

Threshold ferritin and hepcidin concentrations indicating early iron deficiency in young women based on upregulation of iron absorption.

BackgroundPlasma ferritin is a widely used indicator to detect iron deficiency, but the threshold ferritin that defines iron deficiency remains uncertain. Our aim was to define the ferritin concentration at which the body begins to upregulate iron absorption from the diet; this could provide a functionally-defined threshold of incipient iron deficiency. We hypothesized this threshold ferritin concentration would correspond to the threshold hepcidin concentration at which iron absorption begins to increase.MethodsWe performed a pooled analysis of our stable iron isotope studies (n = 1058) conducted from 2006 to 2019 in healthy women (age 18–50 years; mean±SD ferritin 33.7 ± 27.1 μg/L) that measured iron absorption from labeled test meals providing physiological amounts of iron. To fit relationships between iron absorption, ferritin and hepcidin, we used generalized additive modeling, and to identify thresholds, we estimated the first derivatives of the fitted trend to assess inflection points in these relationships.FindingsHepcidin increased linearly with increasing ferritin over the entire range of ferritin values. Iron absorption began to increase below a threshold hepcidin value of 3.09 (95%CI: 2.80, 3.38) nmol/l, above which iron absorption remained stable. Iron absorption began to increase below a threshold ferritin value of 51.1 (95%CI: 49.1, 53.1) µg/l, above which iron absorption remained stable. The latter two findings were internally consistent in that, in the relationship between hepcidin and ferritin, a hepcidin of ~3 nmol/l corresponded to a ferritin of ~51 µg/l.InterpretationBased on physiological upregulation of iron absorption, a threshold ferritin of <50 µg/L, corresponding to a threshold hepcidin of <3 nmol/l, indicates incipient iron deficiency in young women.

Toward a reliable assessment of potential ecological impacts of deep‐sea polymetallic nodule mining on abyssal infauna

AbstractThe increasing demand for metals is pushing forward the progress of deep‐sea mining industry. The abyss between the Clarion and Clipperton Fracture Zones (CCFZ), a region holding a higher concentration of minerals than land deposits, is the most targeted area for the exploration of polymetallic nodules worldwide, which may likely disturb the seafloor across large areas and over many years. Effects from nodule extraction cause acute biodiversity loss of organisms inhabiting sediments and polymetallic nodules. Attention to deep‐sea ecosystems and their services has to be considered before mining starts but the lack of basic scientific knowledge on the methodologies for the ecological surveys of fauna in the context of deep‐sea mining impacts is still scarce. We review the methodology to sample, process and investigate metazoan infauna both inhabiting sediments and nodules dwelling on these polymetallic‐nodule areas. We suggest effective procedures for sampling designs, devices and methods involving gear types, sediment processing, morphological and genetic identification including metabarcoding and proteomic fingerprinting, the assessment of biomass, functional traits, fatty acids, and stable isotope studies within the CCFZ based on both first‐hand experiences and literature. We recommend multi‐ and boxcorers for the quantitative assessments of meio‐ and macrofauna, respectively. The assessment of biodiversity at species level should be focused and/or the combination of morphological with metabarcoding or proteomic fingerprinting techniques. We highlight that biomass, functional traits, and trophic markers may provide critical insights for biodiversity assessments and how statistical modeling facilitates predicting patterns spatially across point‐source data and is essential for conservation management.

Complexity of agricultural economies in the Yiluo region in the late Neolithic and bronze age (3500–221 BC): An integrated stable isotope and archeobotanical study from the Tumen site, North China

AbstractThe region of Yiluo in North China witnessed the development of social complexity in the Neolithic period and the emergence of the first Chinese state society in the early Bronze Age. However, the agricultural economies in the Neolithic–Bronze Age periods of this region and its influence on the social complexity in this area have not been adequately understood, owing to the relative lack of evidence from archeobotany, chronology, and stable isotope analysis in this region. Archeobotanical and isotopic evidence, together with chronological data from the Tumen site, reveals that the complexity of the agricultural economy composed of millet and rice appeared during the late Yangshao period in the Yiluo region and became more intensified in the following Longshan and Bronze Age periods. During the Yangshao and Longshan periods, environmental factors such as landform and hydrology were likely important factors for the diverse agricultural patterns. The complexity of the agricultural economy has an influence on settlement hierarchy and population growth, suggesting that the rise and intensification of the complex agricultural economy was an important driving force in societal development in the Yiluo region.

Dietary carbohydrates and fats in nonalcoholic fatty liver disease.

The global prevalence of nonalcoholic fatty liver disease (NAFLD) has dramatically increased in parallel with the epidemic of obesity. Controversy has emerged around dietary guidelines recommending low-fat-high-carbohydrate diets and the roles of dietary macronutrients in the pathogenesis of metabolic disease. In this Review, the topical questions of whether and how dietary fats and carbohydrates, including free sugars, differentially influence the accumulation of liver fat (specifically, intrahepatic triglyceride (IHTG) content) are addressed. Focusing on evidence from humans, we examine data from stable isotope studies elucidating how macronutrients regulate IHTG synthesis and disposal, alter pools of bioactive lipids and influence insulin sensitivity. In addition, we review cross-sectional studies on dietary habits of patients with NAFLD and randomized controlled trials on the effects of altering dietary macronutrients on IHTG. Perhaps surprisingly, evidence to date shows no differential effects between free sugars, with both glucose and fructose increasing IHTG in the context of excess energy. Moreover, saturated fat raises IHTG more than polyunsaturated or monounsaturated fats, with adverse effects on insulin sensitivity, which are probably mediated in part by increased ceramide synthesis. Taken together, the data support the use of diets that have a reduced content of free sugars, refined carbohydrates and saturated fat in the treatment of NAFLD.

Human mobility at Tell Atchana (Alalakh), Hatay, Turkey during the 2nd millennium BC: Integration of isotopic and genomic evidence.

The Middle and Late Bronze Age, a period roughly spanning the 2nd millennium BC (ca. 2000–1200 BC) in the Near East, is frequently referred to as the first ‘international age’, characterized by intense and far-reaching contacts between different entities from the eastern Mediterranean to the Near East and beyond. In a large-scale tandem study of stable isotopes and ancient DNA of individuals excavated at Tell Atchana (Alalakh, located in Hatay, Turkey), we explored the role of mobility at the capital of a regional kingdom, named Mukish during the Late Bronze Age, which spanned the Amuq Valley and some areas beyond. We generated strontium and oxygen isotope data from dental enamel for 53 individuals and 77 individuals, respectively, and added ancient DNA data of 10 newly sequenced individuals to a dataset of 27 individuals published in 2020. Additionally, we improved the DNA coverage of one individual from this 2020 dataset. The DNA data revealed a very homogeneous gene pool. This picture of an overwhelmingly local ancestry was consistent with the evidence of local upbringing in most of the individuals indicated by the isotopic data, where only five were found to be non-local. High levels of contact, trade, and exchange of ideas and goods in the Middle and Late Bronze Ages, therefore, seem not to have translated into high levels of individual mobility detectable at Tell Atchana.

Measuring Dietary Iron Absorption From Edible Tenebrio molitor and Assessing the Effect of Chitin on Iron Bioavailability: A Stable Iron Isotope Study in Young Women

Abstract Objectives Iron deficiency is estimated to affect up to 1.5–2 billion people worldwide. Edible insects can be a rich source of iron and may have a smaller environmental food print than other animal source foods. Mealworm (Tenebrio molitor) larvae are recognized as an edible insect, but iron bioavailability in humans has not been investigated. Chitin, a major component of insect biomass, is a known iron binder. Our primary objective was to measure fractional iron absorption (FIA) from T.molitor with and without chitin in young women. Secondly, we aimed to assess the effect of the presence of mealworm biomass on iron absorption from iron present in low-phytate maize porridge. Methods Non-anemic females (18–45 years, body weight &amp;lt; 65 kg) were recruited and FIA was measured as erythrocyte incorporation of stable isotopes tracers in red blood cells 14 days after test meal administration. Using a randomized cross over design, three different meals were administered to each subject, consisting of A) a low phytate refined maize porridge with 54FeSO4; B) intrinsically labelled (57Fe) T.molitor with native chitin and extrinsic 58FeSO4; C) intrinsically labelled (57Fe) T.molitor with reduced chitin and extrinsic 58FeSO4. Results Median serum ferritin concentration in the participating subjects (n = 21) was 22.7 µg/L. Iron content in T.molitor larvae was FIA from meals B (58Fe, 5.28%) and C (58Fe, 4.55%) in which mealworm biomass was given in combination with maize porridge did not significantly differ to FIA from maize porridge fed alone (5.84%). In case of intrinsic labelling, FIA from meals B (57Fe, 4.11%) and C (57Fe, 4.03%) were significantly lower compared to maize meal A (P &amp;lt; 0.001). Conclusions FIA from T.molitor was similar to low-phytate containing maize. Presence of mealworm biomass did not enhance or inhibit the FIA of iron present in the maize meal. Furthermore, a chitin reduction process did not show any discernible effect on FIA. T.molitor larvae could be a viable source of iron in the human diet, but iron absorption may be similar to plant-based foods. The study was registered at clinicaltrials.gov as NCT04510831. Funding Sources Coop Research Program, World Food System Center, ETH Zurich, Switzerland.

Modern analogue to past coseismic ground uplift in North Andaman, India

Dynamics of surface geological processes, triggered by coseismic ground uplift following the 2004 Sumatra-Andaman earthquake (Mw > 9.2), provide a modern analogue for assessing the paleoseismic significance of an enigmatic subsurface peat occurrence within beach sands in the western coast of North Andaman Island. The megathrust earthquake uplifted vast stretches of coastal intertidal zones to supratidal levels. As a result, intertidal flora, including mangroves, desiccated and perished. Mass mortality of the flora continued even three years after the earthquake and generated a large volume of forest debris. Coastal waves pushed the debris to the high tide line where the accumulated debris would be gradually buried, and would subsequently transform into linear peat bodies keeping a record of the seismic event in 2004. Accordingly, we have interpreted a linear strand-parallel peat occurrence in beach sand as a record of earlier mass mortality of plants likely associated with a coseismic ground uplift. Stable isotope studies indicate that local intertidal flora is the source of the peat organic matter. Moreover, the 1817 CE calibrated mean AMS radiocarbon age of the peat suggests recurrence of a megathrust earthquake in the Andaman subduction zone about 200 years ago.

Metabolic Study of Stable Isotope Labeled Indolinone Derivative in Hepatocyte Cell by UPLC/Q TOF MS

The aggregation process of α-synuclein (α-syn) is substantial in the pathogenesis of Parkinson's disease. Indolinone derivatives are inhibitors of α-syn aggregates and can be used as PET-based radiotracers for imaging α-syn fibrils. However, no investigations on the metabolism of indolinone derivatives have been reported until now. In the present research, a 13C and 15N isotope labeling strategy was developed to synthesize compound [13C2,15N]-(Z)-1-(4-aminobenzyl)-3-((E)-(3-phenyl)allylidene)indolin-2-one (M0'), which was then used in a study of metabolism in hepatocytes. The metabolites were characterized using accurate mass and characteristic ion measurements. In the metabolic system, compound M0' was the main component (accounting for 97.5% of compound-related components) after incubation in hepatocytes for 3 h, which indicated that compound M0' possessed great metabolic stability. Seven metabolites have been successfully verified by UPLC/Q TOF MS in metabolic studies, including hydroxyl M0' (M1'), hydroxyl and methylated M0' (M2'), N-acetylated M0' (M3'), sulfate of hydroxyl M0' (M4'), the glucose conjugate of M0' (M5'), glucuronide conjugate of M0' (M6'), and glucuronide conjugate of hydroxyl M0' (M7'). The study on metabolism provides the important information to develop effective α-syn aggregate inhibitors and new PET-tracer-related indolinone derivatives.

SuessR: Regional corrections for the effects of anthropogenic CO2 on δ13C data from marine organisms

Abstract Anthropogenic CO2 emissions associated with fossil fuel combustion have caused declines in baseline oceanic δ13C values. This phenomenon, called the Suess effect, can confound comparisons of marine δ13C data from different years. The Suess effect can be corrected for mathematically; however, a variety of disparate techniques are currently used, often resulting in corrections that differ substantially. SuessR is a free, user‐friendly tool that allows researchers to calculate and apply regional Suess corrections to δ13C data from marine systems using a unified approach. SuessR updates existing methods for calculating region‐specific Suess corrections for samples collected from 1850 to 2020. It also estimates changes in phytoplankton 13C fractionation associated with increasing water temperature and aqueous CO2 concentrations, referred to here as the Laws effect. SuessR version 0.1.3 contains four built‐in regions, including three in the subpolar North Pacific (Bering Sea, Aleutian Islands and Gulf of Alaska) and one North Atlantic region (Subpolar North Atlantic). Users can also supply environmental data for regions not currently built into SuessR to generate their own custom corrections. In 2020, net corrections (Suess + Laws corrections) were as follows—Bering Sea: 1.29‰; Aleutian Islands: 1.30‰, Gulf of Alaska: 1.30‰; and Subpolar North Atlantic: 1.31‰ (compared to a global atmospheric CO2 change of ~2.43‰ across the same period). For samples collected in 2020, the net correction exceeds instrumental error (±0.2‰) when making comparisons across only eight years (i.e. 2013–2020). The magnitude of the Suess effect calculated by SuessR aligns with published estimates, whereas the Laws effect is smaller than previously calculated, resulting from updated estimates of average community cell sizes, growth rates and permeability of phytoplankton plasmalemmas (the plasma membrane which bounds the cell) to CO2. The increasing magnitude of the Suess effect means this phenomenon is no longer only of concern to historical ecologists, but now affects contemporary ecological studies using δ13C data. This highlights the importance of a unified approach for generating Suess corrections. The SuessR package provides a customizable tool that is simple to use and will improve the interpretability and comparability of future stable isotopic studies of marine ecology. ​

Patterns of dietary diversity in Holocene north-west South America: new insights from Bayesian stable isotope mixing models

For two decades, stable isotope studies have documented palaeodietary transitions in the Sabana de Bogotá region of north-west South America. Using traditional and Bayesian stable isotope mixing models, this article investigates the contribution of different resources to Holocene human diets. Temporal patterns include dietary emphases on plants during the Early and Middle Holocene, on maize horticulture through the initial Late Holocene and on maize/tuber agriculture during the final Late Holocene; animal protein apparently contributed little across all periods. These results suggest that the management and selection of diverse plants occurred early, and the later emphasis on maize raises universal questions about the role of agriculture in cultural change and social differentiation.

New home, new diet? Reconstruction of diet at the 10th century CE Hungarian Conquest period site of Kenézlő-Fazekaszug from stable carbon and nitrogen isotope analyses

The first Hungarians settled the Carpathian Basin in the 9th and 10th centuries CE, during the Hungarian Conquest. The 10th century CE Kenézlő-Fazekaszug is one of several cemeteries from this period that exist across present-day Hungary. Although stable isotope studies have investigated the diet of medieval Europeans, this paper details the first dietary research performed on a Hungarian Conquest period population. Stable carbon and nitrogen isotope analyses were undertaken on dental enamel (n = 18) and dentin (n = 17) to determine childhood diet. Enamel apatite δ13C values average at −9.5‰ and dentin collagen δ13C values at −16.0‰. Dentin collagen δ15N values have a mean of 11.9‰. Additionally, stable carbon and nitrogen isotope analyses were performed on bone apatite (n = 21) and collagen (n = 22) to determine adulthood diet. Bone apatite δ13C values average at −11.1‰. Bone collagen δ13C and δ15N values have an average of −17.0‰ and 11.5‰, respectively. These results suggest that C3 plants were the primary plant type utilized by the population but also that C4 plants were consumed in varying quantities. This data supports the archaeological evidence that C3 plants dominated C4 plants in early medieval Europe. The δ15N values show that this population consumed moderate amounts of animal protein, as well as that adult males had preferential access to animal protein. This study reveals new information about diet during a formative time in Hungarian history.

Surface texture, mineralogy and stable isotope studies of nodular calcretes preserved in the YTT ash of Padang Terap river basin and lenggong valley, peninsular Malaysia: Implications in its origin and paleoclimatic reconstruction

Rounded to sub-rounded calcrete nodules, preserved in Youngest Toba Tuff (YTT, ~75 ka) ash, exposed at the Padang Terap river basin and Lenggong valley of Malaysia, have been investigated for their micromorphology, mineralogy and stable isotope compositions (δ18O and δ13C) with the aim to interpret their origin, climatic conditions and vegetational scenario in the studied areas. These nodules are associated with cylindrical, pipe-like, root calcretes and highly calcretized ant traces. The FESEM study shows dominance of sparry calcite and microsparite as groundmasses and presence of bacteria microfossils and microbial features. The microfossils are represented mainly by microcodium, calcified pedostructures and organic filaments, whereas, the microbial features as extracellular polymers substances (EPS) and bacillus type bacteria. Mineralogical compositions as reflected by X-ray diffractograms show dominant peaks of calcite followed by quartz, chlorite, illite and palygorskite. The δ18O and δ13C values suggest that the precipitation of calcium carbonate might have happened in in-situ manner that leached under the influence of meteoric water in presence of C4 dominated vegetation during the formations of the nodules. Presence of C4 vegetation in the area suggests that the same had revived after the YTT event. The study suggests that the CaCO3 would have been supplied to the host sediments by dust, rainwater and local geological set-ups during arid, semi-arid and humid climatic conditions.

The Kuh Toto volcanic-hosted copper deposit, Semnan Province, Iran: geochemical, fluid inclusion, and C and O isotopic studies

Supergene copper mineralization occurs at the Kuh Toto deposit, located 25 km to the west of Torud village in the Semnan Province, Iran. Mineralogical, fluid inclusion and stable isotopic (C and O) studies, as well as rare earth element (REE) geochemistry of whole rock and minerals are used to unravel the conditions under which the Cu ores formed. Malachite is the only copper ore mineral, and it is present as veinlets, coatings and small patches in Eocene volcanic rocks. Malachite is accompanied by minor calcite, manganese and iron oxides and oxyhydroxides, clay minerals, epidote, quartz and chrysocolla. Argillic and, to a lesser extent, propylitic hydrothermal alteration partially affected the basic volcanic host rocks. The chondrite-normalized REE patterns of malachite and calcite are similar to those of the volcanic host rocks. They are enriched in LREEs. The volcanic host rocks are enriched in Cu (187 ppm on average). Fluid inclusions hosted in calcite reveal that calcite precipitated from hydrothermal fluids at low temperatures (69–150°C) and low to moderate salinities (7.17–11.10 wt% NaCl equivalent). The oxygen isotopic geothermometry yielded an average temperature of 41°C for malachite formation. Geochemical and fluid inclusion evidence strongly support that mineral-forming elements, including Cu, originated from the associated volcanic rocks. Available data support the view that Cu was likely leached as mobile aqueous Cu 2+ from the volcanic rocks by oxidizing surface waters. When Cu-enriched fluids entered the underlying groundwater environment, Cu was precipitated as malachite in fractures, via recombination with carbonate ions dissolved as CO 2 in meteoric fluids.

Consumption of a Single Dose of Prebiotic Galacto-Oligosaccharides Does Not Enhance Iron Absorption from Micronutrient Powders in Kenyan Infants: A Stable Iron Isotope Study

BackgroundLong-term feeding of prebiotic galacto-oligosaccharides (GOS) increases iron absorption in African infants, but the underlying mechanism and how long GOS need to be fed to infants to achieve an increase in absorption is uncertain. ObjectivesIn Kenyan infants, we tested whether the addition of GOS to a single test meal would affect iron absorption from a micronutrient powder (MNP) containing ferrous sulfate (FeSO4) and another MNP containing ferrous fumarate (FeFum) and sodium iron ethylenediaminetetraacetate (NaFeEDTA). MethodsIn a randomized-entry, prospective crossover study, iron deficient (87%) and anemic (70%) Kenyan infants (n = 23; mean ± SD age, 9.9 ± 2.1 months) consumed 4 stable iron isotope–labeled maize porridge meals fortified with MNPs containing 5 mg iron as FeFum + NaFeEDTA, or FeSO4, either without or with 7.5 g GOS. The primary outcome, fractional iron absorption (FIA), was assessed by erythrocyte incorporation of isotopic labels. Data were analyzed using a 2-way repeated-measures ANOVA. ResultsThere was no significant interaction between GOS and the iron compounds on FIA, and the addition of GOS did not have a significant effect on FIA. There was a statistically significant difference in FIA between the meals fortified with FeSO4 and with FeFum + NaFeEDTA (P < 0.001).Given with GOS, FIA from FeSO4 was 40% higher than from FeFum + NaFeEDTA (P < 0.001); given without GOS, it was 51% higher (P < 0.01). ConclusionsThe addition of GOS to a single iron-fortified maize porridge test meal in Kenyan infants did not significantly increase iron absorption, suggesting long-term feeding of GOS may be needed to enhance iron absorption at this age. This study was registered at clinicaltrials.gov as NCT02666417.

Diagenetic Modifications and Reservoir Heterogeneity Associated with Magmatic Intrusions in the Devonian Khyber Limestone, Peshawar Basin, NW Pakistan

In the present study, an attempt has been made to establish the relationship between diagenetic alterations resulting from magmatic intrusions and their impact on the reservoir properties of the Devonian Khyber Limestone (NW Pakistan). Field observations, petrographic studies, mineralogical analyses, porosity-permeability data, and computed tomography were used to better understand the diagenetic history and petrophysical property evolution. Numerous dolerite intrusions are present in the studied carbonate successions, where the host limestone was altered to dolomite and marble, and fractures and faults developed due to the upwelling of the magmatic/hydrothermal fluids along pathways. Petrographic studies show an early phase of coarse crystalline saddle dolomite (Dol. I), which resulted from Mg-rich hydrothermal fluids originated from the dolerite dykes. Coarse crystalline marble formed due to contact metamorphism at the time of dolerite emplacement. The second phase of dolomitisation (Dol. II) postdates the igneous intrusions and was followed by dedolomitisation, dissolution, and cementation by meteoric calcite. Stable isotope studies likewise confirm two distinct dolomite phases. Dol. I exhibits more depleted δ18O (-15.8 to -9.1‰ V-PDB) and nondepleted δ13C (-2.05 to +1.85‰ V-PDB), whereas Dol. II shows a relatively narrow range of depleted δ18O (-13.9 to -13.8‰) signatures and nondepleted δ13C (+1.58 to +1.89‰ V-PDB). Dolomitic marble shows a marked depletion in δ18O and δ13C (-13.7 to -8.5‰ and -2.3 to 1.95‰, respectively). The initial phase of dolomitisation (Dol. I) did not alter porosity (5.4-6.6%) and permeability (0.0-0.1 mD) with respect to the unaltered limestone (5.6-6.9%; 0.1-0.2 mD). Contact metamorphism resulted in a decrease in porosity and permeability (3.3-4.7%; 0.1 mD). In contrast, an increase in porosity and permeability in Dol. II (7.7-10.5%; 0.8-2.5 mD) and dolomitic marble (6.6-14.7%; 8.2-13.3 mD) is linked to intercrystalline porosity and retainment of fracture porosity in dolomitic marble. Late-stage dissolution and dedolomitization also positively affected the reservoir properties of the studied successions. In conclusion, the aforementioned results reveal the impact of various diagenetic processes resulting from magmatic emplacement and their consequent reservoir heterogeneity.