Isotope Ratios Research Articles

Chapter 8. Isotopic evidence for protohistoric field locations in northeastern Illinois

AbstractIn the western Great Lakes region of the United States, late prehistoric and early historic Indigenous fields are often difficult to investigate because their archaeological signatures are faint and easily destroyed. They have been identified largely via rare remnants of raised fields and historical records. With the majority of Indigenous fields destroyed, important aspects of cultivation remain ambiguous, especially the ecology of cultivated areas. In addition to archaeological indicators of field location, the choice of specific environmental settings (prairie, wetland, upland forest, etc.) can be encoded in the stable isotope ratios of cultigens. Stable carbon‐ and nitrogen‐isotope ratios of maize kernels and wood charcoal from the Middle Grant Creek site (11WI2739), an early 17th century village in northeastern Illinois, are used to better understand agricultural practices during one of the coldest periods of the Little Ice Age.

A bulk extraction method to determine the stable isotope ratios of iron, nickel, copper, zinc, and cadmium in seawater using multi-collector inductively coupled plasma mass spectrometry

A bulk extraction method to determine the stable isotope ratios of iron, nickel, copper, zinc, and cadmium in seawater using multi-collector inductively coupled plasma mass spectrometry

Geochronology, geochemistry, and isotope signatures of porphyries from the dabate Mo—Cu deposit, Western Tianshan, China: Implications for petrogenesis and geodynamic setting

The Dabate deposit in the West Tianshan Orogenic Belt is a large porphyry Mo-Cu deposit with obvious zoning feature. The Dabate pluton is closely related to mineralization associated with the rhyolite and granite porphyries. Copper (Cu) mineralization occurs on the margin of the rhyolite porphyry, and molybdenum (Mo) mineralization occurs in the interior of the rhyolite porphyry. Petrology, zircon U-Pb isotopic data, whole-rock geochemistry, and Sr-Nb-Hf-Pb isotopic data of the rhyolite and granite porphyries in the Dabate Mo-Cu mining zone and to discuss the properties, sources, evolution, and tectonic environment of the magma. Zircon U-Pb age dating shows that the rhyolite porphyry and granite porphyry were formed in 300.1 ± 1.3 Ma and 290.4 ± 5.2 Ma, respectively, and they are geochemically similar. Both are characterized by negative Eu anomalies (δEu = 0.09–0.15 and 0.10–0.11, respectively) and are slightly rich in light rare earth elements (LREE) but depleted in high-field-strength elements (HFSE), which indicates that they are both A2 type granites that underwent high differentiation. The Sr isotope (ISr) values for the rhyolite and granite porphyries range from 0.70564 to 0.70658 and 0.70833–0.70954, respectively. The Nd isotopic composition [εNd(t)] values for both are negative but close to zero (−0.25 to −0.46 and −0.65 to −1.10, respectively), and the two-stage depleted mantle Nd model ages (TDM2(Nd)) are 1.07–1.10 Ga and 1.11–1.14 Ga, respectively. Zircon εHf(t) values are 7.29–11.97 and 6.26–11.08 for rhyolite porphyry and granite porphyry, respectively, and the two-stage Hf model ages (TDM2(Hf)) are 550–848 Ma and 605–916 Ma, respectively. The initial Pb isotope ratios for the rhyolite and granite porphyry are close at (206Pb/204Pb)i = 18.26–18.65, (207Pb/204Pb)i = 15.54–15.64, and (208Pb/204Pb)i = 38.19–38.57. These results indicate that the two porphyries have a mixed source, likely originating from the partial melting of mantle blended with some recently formed lower crust material. The geochronology, geochemistry, and Sr-Nd-Hf-Pb isotope data of existing intrusions in the West Tianshan imply that the Late Carboniferous to Early Permian Dabate area was underplated in a post-collisional extensional setting, and A2-type granite intrusions with related Mo-Cu mineralization were formed.

Chemical inventory of the envelope of the Class I protostar L1551 IRS 5

Episodic accretion in protostars leads to luminosity outbursts that end up heating their surroundings. This rise in temperature pushes the snow lines back, enabling the desorption of chemical species from dust grain surfaces, which may significantly alter the chemical history of the accreting envelope. However, a limited number of extensive chemical surveys of eruptive young stars have been performed thus far. In the present study, we carry out a large spectral survey of the binary Class I protostar L1551 IRS 5, known to be a FUor-like object, in the 3 mm and 2mm bands with the IRAM-30m telescope. As a result, we detected more than 400 molecular lines. The source displays a great chemical richness with the detection of 75 species, including isotopologues. Among these species, there are 13 hydrocarbons, 25 N-bearing species, 30 O-bearing species, 15 S-bearing species, 12 deuterated molecules, and a total of 10 complex organic molecules (l-C4H2, CH3CCH, CH2DCCH, CH3CHO, CH3CN, CH3OCH3, CH3OCHO, CH3OH, CH2DOH, and HC5N). With the help of local thermodynamic equilibrium (LTE) and non-LTE models, we determined the column densities of most molecules as well as excitation and kinetic temperatures. While most of those molecules trace the cold envelope (≲20 K), the OCS and CH3OH emission arise from the warm (>100 K) innermost (<2″) regions. We compared the chemical inventory of L1551 IRS 5 and its column density ratios, including isotopic ratios, with other protostellar sources. A broad chemical diversity is seen among Class I objects. More observations with both single-dish telescopes and interferometers are needed to characterize the diversity in a larger sample of protostars, while more astrochemical models would help explain this diversity, in addition to the impact of luminosity outbursts on the chemistry of protostellar envelopes.

Carbon Isotope Fractionation of Complex Organic Molecules in Star-forming Cores

Recent high-resolution and sensitivity Atacama Large Millimeter/submillimeter Array observations have unveiled the carbon isotope ratios (12C/13C) of complex organic molecules (COMs) in a low-mass protostellar source. To understand the 12C/13C ratios of COMs, we investigated the carbon isotope fractionation of COMs from prestellar cores to protostellar cores with a gas-grain chemical network model. We confirmed that the 12C/13C ratios of small molecules are bimodal in the prestellar phase: CO and species formed from CO (e.g., CH3OH) are slightly enriched in 13C compared to the local interstellar medium (by ∼10%), while those from C and C+ are depleted in 13C owing to isotope exchange reactions. COMs are mainly formed on the grain surface and in the hot gas (> 100 K) in the protostellar phase. The 12C/13C ratios of COMs depend on which molecules the COMs are formed from. In our base model, some COMs in the hot gas are depleted in 13C compared to the observations. Thus, we additionally incorporate reactions between gaseous atomic C and H2O ice or CO ice on the grain surface to form H2CO ice or C2O ice, as suggested by recent laboratory studies. The direct C-atom addition reactions open pathways to form 13C-enriched COMs from atomic C and CO ice. We find that these direct C-atom addition reactions mitigate 13C-depletion of COMs, and the model with the direct C-atom addition reactions better reproduces the observations than our base model. We also discuss the impact of the cosmic-ray ionization rate on the 12C/13C ratio of COMs.

Longitudinal Associations of Sugar-Sweetened Beverage Intake With Serum Carbon Isotope Ratio (CIR) in Youth: Findings From Two Independent Pediatric Cohort Studies

Longitudinal Associations of Sugar-Sweetened Beverage Intake With Serum Carbon Isotope Ratio (CIR) in Youth: Findings From Two Independent Pediatric Cohort Studies

Revealing the ongoing speleogenetic processes in an underwater cave through the application of natural radionuclides and stable isotopes: case study from the hypogene Buda Thermal Karst

The underwater Molnár János Cave in the hypogene Buda Thermal Karst system (Budapest, Hungary) provides a unique site to study the effects of flowing groundwater and the interplay of fluids of different origin. The aim of the present study is to characterize the groundwater in different parts of the cave with temporal resolution, hence describe the recent speleogenetic processes within the cave. This study uses natural radioisotopes (uranium, radium, and radon) besides stable isotope ratios of oxygen and hydrogen to identify the different fluid components. The results show that the majority of the cave is situated in the flow path of the intermediate flow system, discharging in the Boltív Spring. Thus, the dominant recent speleogenetic processes are connected to this lukewarm groundwater. In contrast to previous views, typical hypogene processes, such as mixing corrosion involving thermal waters, are restricted to a narrower area in the cave, to the contact zone of lukewarm waters and the warmer upper water layer around the largest partially air-filled chamber (Kessler Hall). The warmer water layer is the result of free convection. In the air-filled chambers condensation-corrosion might be active. However, its effect is limited to the largest room (Kessler Hall), as it is open to surface conditions. More active mixing corrosion probably occurs deeper, in the area of the Northeastern Margin Fault, which is indicated by the radon content in the Boltív Spring. Regarding the temporal processes, the main driving force can be linked to the water level fluctuations of the Danube, which regulates the discharge of the regional flow-related thermal water upwelling, thus affecting the mixing ratio of the lukewarm waters transported by the intermediate flow systems and the thermal waters, representing the regional flow path, including basinal components.

Carbon Isotope Ratio (CIR) Measured in 24-H Urine Is Associated With Multiple Dietary Exposures in a 15-d Controlled Feeding Study

Carbon Isotope Ratio (CIR) Measured in 24-H Urine Is Associated With Multiple Dietary Exposures in a 15-d Controlled Feeding Study

Compost amendment in urban gardens: elemental and isotopic analysis of soils and vegetable tissues

Urban horticulture poses a sustainable form of food production, fosters community engagement and mitigates the impacts of climate change on cities. Yet, it can also be tied to health challenges related to soil contamination. This work builds on a previous study conducted on eleven urban gardens in the city of Vienna, Austria. Following the findings of elevated Pb levels in some soil and plant samples within that project, the present study investigates the elemental composition of soil and plants from two affected gardens 1 year after compost amendment. Inductively coupled plasma mass spectrometry (ICP-MS) analysis of skin, pulp and seeds of tomato fruits revealed minor variations in elemental composition which are unlikely to have an impact on food safety. In turn, a tendency of contaminant accumulation in root tips and leaves of radishes was found. Washing of lettuce led to a significant reduction in the contents of potentially toxic elements such as Be, Al, V, Ni, Ga and Tl, underscoring the significance of washing garden products before consumption. Furthermore, compost amendments led to promising results, with reduced Zn, Cd and Pb levels in radish bulbs. Pb isotope ratios in soil and spinach leaf samples taken in the previous study were assessed by multi-collector (MC-) ICP-MS to trace Pb uptake from soils into food. A direct linkage between the Pb isotopic signatures in soil and those in spinach leaves was observed, underscoring their effectiveness as tracers of Pb sources in the environment.Graphical

Water Geochemistry and Stable Isotope Changes Record Groundwater Mixing After a Regional Earthquake in Northeast India

AbstractRecorded earthquake‐induced changes in hydrogeological systems date back over 2,000 years. As a part of our ongoing hydrogeochemical monitoring effort to study such changes, we collected 406 groundwater samples twice a week between February 2021 and July 2023 from two bore wells in the Kopili fault zone of Northeast India. We analyzed stable isotope ratios (δ2H, δ18O) and dissolved element concentrations to obtain a 2.5‐year hydrogeochemical time series and responses to multiple regional earthquakes (Mw ≥ 3) within the monitored period. We find significant but transient anomalies in both the chemical and isotopic composition of groundwater at one of the observation wells (OW1) after the 2021 Assam Mw 6.4 earthquake, followed by prolonged alterations in the hydrochemistry at both wells. We do not identify any precursory changes. Using multivariate statistical techniques and analyzing compositional changes before and after the mainshock, we infer that the hydrochemical anomalies at OW1, representing an immediate response to the mainshock, can be attributed to the potential breach of a hydrological barrier. This, in turn, allowed the infiltration of new water into the OW1 aquifer, potentially sourced from the nearby Brahmaputra River. Subsequently, during the post‐anomaly period, the earthquake‐induced fracturing and the associated changes in permeability sustained a prolonged period of mixing between surface water and groundwater, resulting in newly formed hydrochemistry at both wells. Our findings highlight the dynamic nature of aquifer properties during earthquakes. Long‐term continuous evaluation of such changes may provide new insights into feedback between tectonics and fluid flow in the crust.

Animal Protein and Related Intakes Associated With Plasma Carbon and Nitrogen Isotope Ratio Biomarkers in a Controlled Feeding Study of Postmenopausal Women

Animal Protein and Related Intakes Associated With Plasma Carbon and Nitrogen Isotope Ratio Biomarkers in a Controlled Feeding Study of Postmenopausal Women

Reliability Evaluation for Mercury Stable Isotope Ratio Measurement by MC-ICP/MS

This study assessed the reliability of Mercury (Hg) stable isotope ratio measurements using MC-ICP/MS hyphenated with three different systems: wet plasma, dry plasma, and a cold vapor generator (CVG). Precision measurements using wet plasma improved with concentration, showing a range of 0.4 - 10.0% at 100 µg/L, with corresponding accuracy from 0.0 – 0.4%. By contrast, dry plasma demonstrated precision between 0.02 - 2.2% at 10 µg/L for 202/198Hg, with accuracy ranging from 1.2 - 1.4%. The CVG system, however, displayed significantly enhanced accuracy, from 0.2% for 199/198Hg to 0.9% for 204/198Hg at 0.1 µg/L. The study also incorporated a mass bias correction using a thallium (NIST 997 standard) internal spike, emphasizing the importance of maintaining a total Hg beam above 0.5 V to ensure measurement precision and accuracy. The findings suggest that the CVG method is most suitable for environmental samples with trace Hg concentrations, while both dry and wet plasma systems can serve effectively at higher concentrations (≥ 100 µg/L), given their analytical convenience and performance.

Regional foraging areas of green turtles (Chelonia mydas) nesting at Aldabra Atoll: insights from stable isotopes and satellite telemetry

Sea turtles spend the majority of their lives at foraging grounds. These areas are important for population persistence but generally occur in coastal habitats, which are under increasing human pressure. Identifying key foraging areas is therefore an important step to understanding critical sea turtle habitats, and therefore their threats. Isotope ratios (δ15N, δ13C) from skin tissues of 90 green turtles (Chelonia mydas) nesting at the regionally important rookery of Aldabra Atoll, Seychelles, were analyzed with samples collected during two periods: 51 samples from March to September 2021, and 39 samples from January to April 2022. These analyses were complemented by nine satellite tracks to identify key foraging areas. Hierarchical clustering and discriminant function analysis identified two main foraging areas: the East African coast (Tanzania and Somalia) and northern Madagascar. Isotopic values indicated that the majority of green turtles nesting at Aldabra forage at one of these two areas, with slightly more green turtles visiting the East African coast. Geographical isotopic patterns were not found latitudinally, suggesting a potential limit to this approach for coastal areas in the Western Indian Ocean. However, we found longitudinal variation of δ13C and δ15N that few studies have reported. This is the first study in this region to combine satellite telemetry and stable isotope analysis to assign likely foraging areas of green turtles and advances understanding of the complex migration patterns and foraging ecology of this species. We demonstrate the potential and the limitations of stable isotope analysis for identifying/characterizing green turtle foraging areas in this region.

Testing the Sample Preparation Method and Oxygen Isotopic Analysis of Tooth Enamel for the Reconstruction of the Birth Seasonality of Ovicaprines (the Case of Teeth from Istykskaya Cave, Eastern Pamir)

Cyclic variations of δ18O along the growth line of M2 and M3 molars provide information about the seasonality of enamel formation and thereby about reproductive seasonality in animals, taking into account the time of tooth eruption and full enamel maturation. Determination of birth seasonality of small ruminants is relevant to the reconstruction of pastoralist strategies. Two peaks of reproductive activity per year are one of the most reliable indicators of human control of the small ruminants. As part of this work, for the first time in Russia, a method of sample preparation and analysis of oxygen isotope ratios in the tooth enamel of small ruminants is proposed. Traditionally, breeding seasonality was evaluated by the isotopic analysis of carbonates, the content of which in dental enamel is only 4 %. According to a new approach, oxygen from a sample is converted to gaseous CO by the interaction of enamel with carbon in a helium flow under 1300 °С, enabling one to measure δ18O in all components of the dental enamel, including phosphates, which make up 90 % of enamel mass and are resistant to diagenesis. In this study, four sample preparation protocols depending on the degree of preservation of teeth and their age were tested: (A) cleaning and sampling of enamel, (B) treatment by H2O2, (C) treatment by NaOCl and CH3COOH, and (D) extraction of Ag3PO4. Results show that for assessing seasonality breeding, it suffices to evaluate the lowest and the highest δ18O along the tooth growth line. If the preservation of sample is good, minimal chemical treatment is enough to observe these extremes.

Otolith radiocarbon signatures provide distinct migration history of walleye pollock around Hokkaido, Japan in the North-Western Pacific.

Trace elements and stable isotope ratios in otoliths have been used as proxies for the migration history of teleosts; however, their application in oceanic fishes remains limited. This study reports the first use of radiocarbons in otoliths to evaluate the horizontal migration histories of an oceanic fish species, the walleye pollock Gadus chalcogrammus. We conducted radiocarbon analyses of three stocks sourced from Hokkaido, Japan. The radiocarbon concentrations from the outermost portion of the otoliths from the Japanese Pacific, Northern Japan Sea (JS), and Southern Okhotsk Sea (OS) stocks were in general agreement with the seawater radiocarbon concentration of the sampling region, suggesting that pollock of all three stocks generally inhabited the within the sea region where each pollocks were sampled throughout their life cycle. However, the radiocarbon signals also provided some indications that some JS and OS stocks may be migrating between different sea regions. The proposed novel approach of reconstructing the individual migration history of marine fish using radiocarbon in otoliths may help examine fish migration with a higher temporal and spatial resolution that could not be achieved by trace elements and stable isotope ratios.

Study on the Chemical Composition and Lead Isotope Ratios of Lead Glaze Used on Blue Tiles from Gyeoungbokgung Palace

Study on the Chemical Composition and Lead Isotope Ratios of Lead Glaze Used on Blue Tiles from Gyeoungbokgung Palace

Investigating nuisance dust complaints: Combining high frequency dust deposition records and source identification using integrated microanalytical techniques

While ducted dust emissions from industry are usually well regulated and controlled, fugitive dust emissions can be difficult to quantify or differentiate from off-site emissions, particularly where fugitive emissions are transient or intermittent. In this study, sources of nuisance dust were investigated using a novel dust deposition sampling methodology, followed by chemical and mineralogical analysis using optical microscopy, x-ray diffraction (XRD), scanning electron microscopy with energy dispersive x-ray spectrometry (SEM-EDS), and isotope ratio mass spectrometry analysis. Dust deposition over 24 h was collected on horizontally orientated 300 mm square glass panels at 6 sites in the region of interest. This method captured very small (<10 mg) masses of dust and could distinguish very small variations in dust deposition at different sites and on different days. Comparison samples collected from potential dust sources at a nearby lime manufacturing facility, and other potential fugitive dust sources in the region were differentiated using XRD mineralogy, visual appearance by optical microscopy and SEM-EDS analysis of individual particles. Comparison of selected dust samples to reference samples indicated most dust deposition at the study sites consisted of soil or sand. However, dust deposition at two sites was sometimes composed of a material that was similar in composition to lime that had been rehydrated to portlandite, but not yet fully carbonated to calcite. Subsequent analysis of δ13C and δ18O for selected dust samples from these two sites were consistent with rapid and recent carbonation of small particles in an alkaline environment, which could have occurred during the atmospheric release and transport of lime, and ruled out fugitive dust emission from lime stockpiles existing on site. Combining the information obtained from high frequency record of dust deposition with targeted mineralogical, isotopic and morphological examinations provided new insight into the source of fugitive dust emissions in this area.

Hydrogen Isotope Fingerprinting of Lipid Biomarkers in the Chinese Marginal Seas

AbstractThe hydrogen isotope ratio (δ2H) of lipid biomarkers from phytoplankton and terrestrial plants were measured in surface sediments from Chinese marginal seas (CMS), in order to evaluate processes affecting their spatial distribution, and by extension, the controls on organic carbon cycling in these dynamic marginal seas. The dinoflagellate sterol dinosterol and the microalgal sterol brassicasterol had low δ2H values (&lt;−300%) near the mouth of the Yangtze River. Near the mouth of the Yellow River, dinosterol again had low δ2H values but brassicasterol had intermediate (−292 to −281%) δ2H values. This discrepancy in the δ2H values of two phytoplankton sterols may be explained by the timing of dinoflagellate production relative to that of brassicasterol producers (e.g., diatoms). The δ2H values of C16:0 fatty acid, synthesized by all organisms, had intermediate δ2H values (−199 to −178%) near the Yangtze River and lowest δ2H C16:0 values (−216 to −206%) occurred near the old Yellow River delta. The lowest δ2H C28:0 values (&lt;−184%) occurred adjacent to rivers, suggesting that leaf‐wax lipids produced on the loess plateau, which are enriched in 2H, may contribute less to the nearshore environment than the offshore regions. Higher δ2H C28:0 values offshore may be explained by a larger contribution of leaf wax fatty acids from aerosols relative to river‐borne suspended particles. Lipid biomarker δ2H fingerprinting thus provides a new tool for deciphering the controls on organic carbon cycling and accumulation in the dynamic CMS.

Carbon Isotope Chemistry in Protoplanetary Disks: Effects of C/O Ratios

Carbon isotope fractionation of CO has been reported in the disk around TW Hya, where elemental carbon is more abundant than elemental oxygen ([C/O]elem > 1). We investigated the effects of the [C/O]elem ratio on carbon fractionation using astrochemical models that incorporate isotope-selective photodissociation and isotope exchange reactions. The 12CO/13CO ratio could be lower than the elemental carbon isotope ratio due to isotope exchange reactions when the [C/O]elem ratio exceeds unity. The observed 12CO/13CO and H12CN/H13CN ratios around TW Hya could be reproduced when the [C/O]elem ratio is 2–5. In the vicinity of the lower boundary of the warm molecular layer, the formation of ices leads to the gas-phase [C/O]elem ratio approaching unity, irrespective of the total (gas + ice) [C/O]elem ratio. This phenomenon reduces the variation in the 12CO/13CO ratio across different [C/O]elem ratios.

Genesis of the Late Cretaceous mafic–intermediate intrusions in the giant Gejiu Sn–Cu ore field and its metallogenic significance

The giant Gejiu ore field, located in the southeastern Yunnan Province, China, developed a large-scale Sn–Cu mineralization related to the Cretaceous felsic–mafic magmatism. However, the genesis of Cretaceous mafic–intermediate intrusions remains controversial, which limits our understanding of the Cu source, Sn–Cu symbiotic mechanism, and geodynamic setting of the Gejiu region. To elucidate these issues, we conducted geochronological and geochemical evaluations on the Gejiu mafic–intermediate intrusions, including gabbro, syenite, and monzonite. The mafic–intermediate intrusions formed in 82.1–83.8 Ma, which are contemporaneous with ore-forming granites and ore bodies within the error range. Combined with the cumulus texture in gabbro, linear or parallel elemental plots, and similar and enriched Sr–Nd–Hf isotopes ((87Sr/86Sr)I = 0.708870–0.709811; εNd(t) = − 5.24–−7.70; εHf(t) = − 4.8–2.5), the gradually increased Sr isotopes from gabbro through syenite to monzonite indicated that the Gejiu mafic–intermediate intrusions were formed by fractional crystallization and varying degrees of crustal assimilation of partial melts of an enriched lithospheric mantle.Based on the above research, we compiled geochronological and geochemical data of magmatic–metallogenic events in the region. The Sr–Nd isotopic and elemental ratios (i.e., Zr/Hf, Nb/Ta, Rb/Sr and Ba/Rb) of the Gejiu granites are located between the mafic–intermediate intrusions and spatially temporally connected Laojunshan granites, which indicate that the magma mixing between the enriched mantle–derived Cu-rich magma and metasedimentary rock–derived Sn-rich granitic magma generated Sn–Cu-rich granitic magma. This magma then evolved into the giant Gejiu Sn–Cu deposit via crystal fractionation and fluid exsolution. Combined with the regional geological data and spatiotemporal framework of Sn–polymetallic deposits, the magmatic–metallogenic model of the giant Gejiu Sn–Cu ore field further demonstrates that the southwestern slab rollback of the Neo-Tethyan oceanic plate during the Late Cretaceous controlled its formation.