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Rationale: Laser‐based analyzers are widely used in ecohydrology to analyze plant water isotopic compositions (δ18O and δ2H). The suitability of three different water extraction and isotope equilibration techniques was compared. We examined whether co‐extracted volatile organic compounds (VOCs) affect laser‐based isotope measurements and used the instrument's spectral parameters to post‐correct for interfering VOCs. Methods: Cryogenic vacuum extraction, vapor headspace equilibration in bags, and vapor equilibration in situ probes were used to extract liquid water or water vapor for laser‐based isotope analysis (cavity ring‐down spectrometry, CRDS). Isotope data were calibrated by standards for each method separately. Spectral parameters of the instrument, appropriate to identify spectral interferences with MeOH and CH4, were identified and used for post‐correction. Differences between the three methods and between the origins of the vegetables were identified by statistical tests. Results: VOCs were found in various amounts for the three different methods. They were co‐extracted or co‐equilibrated during the different extraction or equilibration methods. Correlation coefficients of isotope data and "CH4" (spectral parameter) were 0.99 or better; however, slopes for δ18O were similar on different instrument types but different for δ2H. Our correction approach improved results and inter‐comparability of the methods considerably without knowing the chemical composition of the plant sap. Conclusions: All three methods were sensitive enough to distinguish and resolve differences in natural abundance. Data quality was improved by the "CH4 correction" approach but could probably be optimized by a plant species–specific correction. Standardized tools for contaminant removal or post‐correction applications from manufacturers, in particular for vapor‐mode analysis, are still needed. [ABSTRACT FROM AUTHOR]

Rationale: The analysis of the three sulfur stable isotope ratios (33S/32S, 34S/32S, 36S/32S) is routinely performed by gas‐source isotope ratio mass spectrometry (IRMS) on the SF6 gaseous molecule, collecting SF5+ ions at m/z ~ 127, 128, 129 and 131. High precision and accuracy are commonly achieved owing to a lack of correction because fluorine has only one isotope and the inert nature of the SF6 molecule. The analysis of the 36S/32S ratio is, however, complicated by the low abundance of 36S (~0.015%) and the possible occurrence of trace amounts of fluorocarbon compounds leading to 12C3F5+ ions at m/z ~ 131, i.e. where 36SF5+ ions are collected. Methods: We used gas‐source high‐resolution IRMS to better characterize the nature of possible interferences, and we tested novel types of filaments in order to investigate their influence on possible interferences. Results: We confirm that the 12C3F5+ ion represents the main isobaric interference at m/z ~ 131. We also demonstrate that tungsten fluoride adducts are formed from the reaction of fluorine ions derived during fragmentation of the SF6 molecule with the hot tungsten filament. These reactions lead to the formation of e.g. WF5+, WF4+, WF3+ ions, including doubly charged ions. WF4++, in particular, leads to isobaric interference on m/z ~ 128, 129 and 131 from 180WF4++, 182WF4++ and 186 WF4++ ions, respectively. Because 180W (0.12%) is at low abundance, its influence on δ33S measurements would remain negligible, but 182W (26.5%) and 186W (28.4%) lead to scale contraction for both δ34S and δ36S. Conclusions: Rather than correcting for these interferences, or working at high mass resolution, we suggest avoiding W isobaric interferences by using other types of filaments, with initial reports on both pure Re filaments and Y2O3‐coated W filaments. [ABSTRACT FROM AUTHOR]

The zircon provenances of the late Paleoproterozoic metasedimentary rocks are important for assembling Proto-Yangtze and its reconstruction in the Nuna supercontinent. We present a dataset involving 363 detrital zircon U-Pb dating and 165 Hf isotope analyses from the Laochanghe Formation of the Dahongshan Group in the southwestern Yangtze Block. New detrital zircon U-Pb ages, combined with the heterogeneity of sedimentary strata and available magmatic age data, suggest that the maximum depositional age of the Laochanghe Formation cloud be younger than 1.81 Ga and older than 1.74 Ga. The zircon U-Pb-Hf isotope compositions of the volcanic and metamorphic rocks overlap with those of the late Paleoproterozoic metasedimentary rock, suggesting the southwestern Yangtze Block provided provenance at 1.9, 2.3, and 2.7 Ga. This characteristic is significantly different from the northern Yangtze Block only provided partial provenance at 1.9 and 2.7 Ga. The northern and southwestern of the Yangtze Block jointly provide material for the late Paleoproterozoic metasedimentary rocks, combining synchronous late Paleoproterozoic magmatism and metamorphism, indicative of the formation of the proto-Yangtze Block in response to the accumulation of the Nuna supercontinent. Additionally, the potential provenance areas of the late Paleoproterozoic metasedimentary rock in the southwestern Yangtze include the northwestern Laurentia and southern Siberia, excluding the northern Australian, and Cathaysia. These findings indicate that the southwestern Yangtze may have been located between northwestern Laurentia and southern Siberia during the partial fragmentation of the Nuna supercontinent, enhancing our understanding of changes in the Nuna supercontinent over time. [ABSTRACT FROM AUTHOR]

Fragments of marble revetment and floor slabs as well as some broken statuary and vessels were recovered from the excavation of a Roman temple in the harbor town of Berenike on the Red Sea coast of Egypt. Petrographic analyses, including optical, cathodoluminescence, and scanning electron microscopy as well as isotopic analyses (δ13C, δ18O, 87Sr/86Sr), were conducted to determine the provenance of the marble. The aim was to reconstruct the commercial ties that led to this prized building stone being brought to Berenike. Most, if not all, of the slabs are of banded gray to white marble showing properties indicative of a Prokonnesian origin. This marble, exploited on Marmara Island (Sea of Marmara, Turkey) and extensively utilized throughout the Mediterranean, including Egypt from at least the second century A.D., might have been procured from the marble depots in Alexandria. This could have involved engaging a team of Bithynian master craftsmen for the project, presumably to embellish the main temple of the city during the reign of the Roman emperor Hadrian. The statuary and vessel finds are composed of white marble representing several sources. Some coarse‐grained specimens were surely extracted in Prokonnesos. For others, the source is uncertain and the likely candidates are Prokonnesos, Paros (Cyclades, Aegean Sea), and Ephesos (Aegean coast of Asia Minor). The fine‐grained varieties represented high‐quality Dokimian (Afyon region, Asia Minor) and most likely expensive Parian (lychnites type) marble. Marble from the ancient Gebel Rokham quarries in Egypt was also examined for comparison, but its properties have excluded this source in the case of the marble artifacts from Berenike analyzed in this work. [ABSTRACT FROM AUTHOR]

• Omnivory is a key consumer parameter that should be quantified in soil food webs. • Soil food web connections to aboveground and aquatic networks need more attention. • Cross-ecosystem fluxes via soil-borne insects and to vertebrates are understudied. • New methods facilitate understanding of soil food webs as an open ecosystem pool. Soil food webs were long considered an ecosystem sink for primary production and a black box of reticulated interactions. Quantification of multiple and changing interactions among consumers and resources within and beyond soil food webs stands up as a major challenge. In this mini-review/opinion paper, I present development of ideas on soil food-web structure focusing on resource omnivory – a central characteristic that is linked to food-web structure and stability. There is plenty of empirical evidence for trophic differentiation among soil invertebrates along different food-web dimensions (food resources, trophic levels, microhabitats, time). This comes along with the pervasive idea of widespread omnivory in soil food webs. I argue that we need to quantitatively assess multiple-resource feeding by soil consumers and related drivers across various taxa and different ecosystem types to come closer to predictions of soil food-web structure and dynamics. At the meta-ecosystem level, cross-ecosystem omnivory (i.e. feeding across energy fluxes from different ecosystems) plays an important role in connecting soil with aboveground and aquatic food webs. Aboveground-belowground studies have been focusing on the interfaces such as the rhizosphere and litter surface. Broader cascading impacts of the energy and organismic fluxes across these interfaces within the recipient ecosystem are, however, less understood. Of particular interest here are connections of vertebrate communities to soil food webs and the central role of soil-borne insects in cross-ecosystem energy exchange. Interactions between soil and aquatic food webs span for dozens to hundreds of meters from the terrestrial-aquatic interface, transferring significant amount of energy and matter between these ecosystems. Consequent changes of the structure and functioning in the recipient ecosystem requires more attention, especially how biodiversity-ecosystem functioning relationships manifest across ecosystems. Continuously developing methods, such as compound-specific isotopic analyses, can facilitate quantification of cross-ecosystem omnivory, helping to understand effects of food-web changes across the ecosystem borders. Overall, I present soil food webs as an open and dynamic pool with multiple cross-ecosystem connections and call for quantitative studies in this direction. [ABSTRACT FROM AUTHOR]

Lead (Pb) poisoning is a significant threat to Aotearoa New Zealand's endangered kea (Nestor notabilis), an avian species important to Māori. Historically, exposure was thought to be from lead‐containing building materials; however, recent field observations suggest lead‐based ammunition as an additional source. We used stable lead isotopes to investigate the sources of lead to kea. Comparing 207 Pb/206 Pb ratios in kea blood (n = 91) to both ammunition and building materials, we found approximately one‐third of exposed kea (blood lead > 10 µg/dL) had lead isotope ratios consistent with exposure to lead‐based ammunition. As lead ammunition is still used, including in government‐sponsored culling programs, our data indicate an urgent need to shift toward non‐lead ammunition use to prevent further poisoning and aid conservation efforts. Collaborating with tangata whenua/Māori guardians, we advocate for immediate policy changes to eliminate lead‐based ammunition in kea habitat to safeguard this endangered culturally treasured species from extinction. [ABSTRACT FROM AUTHOR]

Fluid inclusions are a window into deep geological fluids, providing unique access to their nature and composition. The isotopic composition of CO2 and CH4 hosted in fluid inclusions is a powerful proxy to assess the origin and transformation of deep geological fluids, giving insights into carbon sources, fluxes, and degassing in a wide variety of geodynamic settings. Over the last 5 decades, techniques have been developed to extract fluid inclusions from their host minerals and measure their bulk composition. These techniques are often challenged by analytical artifacts including high blank levels of CO2 and CH4, fluid re-speciation, gas adsorption, and diffusion. Since these processes may alter the pristine composition of gases liberated from fluid inclusions, rigorous protocols are needed in order to evaluate the isotopic integrity of the extracted volatile species. In this study, we introduce new protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a Cavity Ring-Down Spectroscopy (CRDS) analyser (Picarro G2201-i). Two mechanical fluid extraction techniques are compared: ball milling in ZrO2 jars and sample crushing in a stainless steel sealed tube under a hydraulic press. Blanks and isotopically labelled tests with the ball milling technique suggest that rotation speed, grinding stock filling degree and filling type alter the CH4 and CO2 concentrations and isotopic compositions measured by the CRDS analyser. In contrast, the crushing technique does not generate measurable quantities of blank CH4 and CO2. The protocols presented in this study allow to extract, detect, and analyse δ13C of CH4 and CO2 for concentrations above 10 and 1,000 ppm respectively. Interlaboratory experiments allowed to replicate previously measured δ13C-CH4 values in natural fluid inclusions within 1‰ with both extraction techniques. This study highlights the potential of combining simple bulk off-line fluid inclusion extraction techniques with a CRDS analyser for δ13C analysis of CO2 and CH4 without gas separation being required. [ABSTRACT FROM AUTHOR]

Ferruginous conditions, defined by anoxia and abundant dissolved ferrous iron (Fe2+ aq), dominated the Precambrian oceans but are essentially non-existent in a modern, oxygenated world. Ferruginous meromictic lakes represent natural laboratories to ground truth our understanding of the stable Fe isotope proxy, which has been used extensively in interpreting the origins of Fe-rich sedimentary rocks like iron formations (IFs) and the interactions of early life with high-Fe2+ aq conditions. Here we report comprehensive geochemical and Fe isotopic analyses of samples collected in May and August 2022, and March 2023, from Deming Lake, Minnesota, a ferruginous meromictic lake that undergoes surface freezing in winter and never becomes euxinic. Through chemical and Fe isotopic analyses of different putative Fe sources to Deming Lake; including eolian input trapped in winter ice cover, nearby bogs, and regional groundwaters sampled at surface springs; we find that a groundwater source provides the best chemical and Fe isotopic match for Deming Lake and can support Fe2+ aq -rich waters at depth that maintain a permanent chemocline at ∼12 m. The ice-free Deming Lake water column can be split into three layers dominated by distinct Fe cycling regimes. Layer (I) extends from the lake surface to the base of the oxycline at ∼6 m, and its Fe cycling is dominated by isotopically light Fe uptake into biomass, likely from stabilized dissolved Fe3+, with variable eolian lithogenic influences. Layer (II) extends between the oxycline and the chemocline at ∼12 m and is dominated by partial Fe2+ aq oxidation on approach to the oxycline, with the formation of variably isotopically heavy Fe3+-bearing particles. Layer (III) underlies the chemocline and is defined by Fe2+ phosphate (vivianite) and carbonate saturation and precipitation under anoxic, Fe2+ aq -rich conditions with little Fe isotopic fractionation. The ice-covered winter water column features more homogenous Fe chemistry above the chemocline, which we attribute to seasonal homogenization of Layers (I) and (II), with suppressed ferric particle formation. Authigenic Fe minerals with non-crustal (light) Fe isotopic compositions only appreciably accumulate in sediments in Deming Lake underlying the chemocline. All sediments deposited above 12 m appear crustal in their Fe isotopic, Mn/Fe, and Fe/Al ratios, likely revealing efficient reductive dissolution of Fe3+-bearing lake precipitates and remineralization of Fe-bearing biomass. We find limited fractionation of Fe isotopes in the ice-covered water column and suggest this provides evidence that substantial delivery of oxidants is required to generate highly fractionated Fe isotopic compositions in Sturtian Snowball era IFs. By comparing Fe isotopic and Mn/Fe fractionation trends in the different Deming Lake layers, we also suggest that correlations between these two parameters in giant early Paleoproterozoic IFs requires the simultaneous deposition of multiple authigenic phases on the ancient seafloor. Finally, high-precision triple Fe isotopic analyses of dissolved Fe impacted by extensive oxidation near the Deming Lake oxycline reveal that the slope of the mass fractionation law for natural, O 2 -mediated Fe2+ aq oxidation is identical to those previously defined for both UV photo-oxidation, and for an array of highly fractionated Paleoproterozoic IFs. [ABSTRACT FROM AUTHOR]

Rationale: Helium (He) and energy shortages have caused price increases and reduced their availability. Using three combustion reactions per acquisition of carbon and nitrogen isotope ratios saves 50% He and energy during the elemental analysis/isotope ratio mass spectrometry (EA/IRMS). This approach needs to be tested for sulfur isotope (δ34S) analyses. Methods: A new method to measure δ34S in three sequential combustion reactions within one EA/IRMS acquisition was developed. The same material or blank samples could be used in the three reactions. After SO2 was used, a N2 purging method was employed to prolong the lifetime of the valves in the EA/IRMS interface. The 3×EA/IRMS was applied to measure δ34S in precious samples, such as Ag2S from acid‐volatile and chromium‐reducible sulfur extracted with a multiple‐port setup. Results: The 3×EA/IRMS‐δ34S method was validated with replicate analyses of international reference materials and laboratory standards with a wide range of mineralogical compositions and δ34S values. The method provided a strategic advantage for the δ34S measurements of small precious samples (measured between blanks). The accuracy and precision of the 3×EA/IRMS values effectively matched those obtained using conventional EA/IRMS, with good agreement between the mean ± SD values and the recommended values with their uncertainties. Conclusions: Compared with the conventional EA/IRMS, the proposed method provides accurate and precise δ34S measurements of the sulfate and sulfide samples while saving approximately 50% of He, energy, SO2 reference gas, O2, analysis time, and cost. Notably, 3×EA/IRMS can provide up to three δ34S values unaffected by memory effects. [ABSTRACT FROM AUTHOR]

The sediment delivery from Hainan island into the NW South China Sea during the Quaternary is less well-defined. An investigation into the uplift, exhumation and fluvial geomorphology of the Hainan island is crucial for improving our understanding on the source-to-sink system in this region. In this study, we employed the digital elevation analysis, the stream power incision model and the cosmogenic nuclide isotope analysis to unravel how and why the Hainan island provide sediment to the NW South China Sea. The results show that the average HI values of the main catchments on the Hainan island are below 0.35, which indicates that the rivers on the Hainan island tend to be stable. Aftermapping the channel steepness index of the Hainan island, a high channel steepness index is constrained in the central and western Hainan island. The c analysis shows minor variations in c values across the Hainan island, except of the watershed between the Wanquanhe and Nandujiang rivers, as well as that between the Changhuajiang and Nandujiang rivers, which indicates the potential migration of the river watersheds here. In addition, we carried out the cosmogenic nuclide 10Be analysis on the river sand from the Hainan island. The spatial distribution of 10Be concentrations is identified to be high in the west and lowin the east. The catchment-averaged erosion rates are quantified to be 35m/Myr, 42.5 m/Myr and 69.9 m/Myr for the Changhuajiang, Wanquanhe and Lingshuihe catchments, respectively. We also estimated the sediment deliveries from the Changhuajiang, Wanquanhe and Lingshuihe catchments to the Qiongdongnan and Yinggehai Basins to be 0.46 Mt/yr, 0.45 Mt/yr and 0.21 Mt/yr, respectively. We compared our results of the fluvial geomorphology analysis and erosion rate estimates of the Hainan island with those of the Taiwan island. We concluded that the difference of the erosion pattern and river evolution of the Hainan and Taiwan islandsmay be associated with the variation of the tectonics. Our investigation on the evolution of the Hainan island will improve our understanding on the source-to-sink systems in the NW South China Sea. [ABSTRACT FROM AUTHOR]

Explicit identification of hydrochemical processes and their controlling factors within groundwater systems is critical for the sustainable utilization of water resources in coastal urban areas. This study was undertaken in the North Coastal Region of Jiaozhou Bay (NCRJB), located in the eastern part of Shandong Province, China, an area grappling with significant issues of groundwater quality degradation and water scarcity. A total of 105 groundwater samples and 34 surface water samples, collected from 2020 to 2024, were analyzed and studied using various hydrogeological tools, multivariate statistical analyses, and water quality assessment methods. These include the Piper diagram, hydrochemical facies evolution diagram (HFE-D), Principal Components Analysis (PCA), correlation analysis, stable isotope analysis, Water Quality Index (WQI), and USSL diagrams. The results indicated that all surface water and pore groundwater samples were categorized as Na-Cl type, exhibiting high Total Dissolved Solids (TDS) and Electrical Conductivity (EC) values, characteristics that render them poor to unsuitable for drinking and irrigation purposes. The fracture groundwater is predominantly of the Ca-Na-Cl mixed type, with average suitability for irrigation and a limited proportion (22.5%) deemed suitable for drinking. Seawater intrusion, primarily through the surface water system, and the impact of human activities were identified as the predominant controlling factors con-tributing to the degradation of the local groundwater environment. Field empirical investigations further validated the results derived from hydrogeological assessments, multivariate statistical analyses, and isotopic approaches. The long-term shifts in hydrochemical properties, along with the latent threat of seawater intrusion, exhibit an upward trend during the dry season and show a certain degree of mitigation during the wet season. This study highlights that field investigations, in conjunction with hydrochemical tools, multivariate statistical analyses, and stable isotope analysis, can successfully furnish reliable insights into the predominant mechanisms governing regional groundwater evolution within the context of long-term and intricate envi-ronmental settings. [ABSTRACT FROM AUTHOR]

Stone circles of the Wielbark culture, such as those found in Grzybnica, have long fascinated researchers, who debate their function and significance. The aim of the presented study is to determine the origins and subsistence strategies of the population buried near the stone circles in Grzybnica, which may help highlight the role of these sites within Wielbark communities. For analysis, human remains from the cemetery in Grzybnica, West Pomeranian Voivodeship, Poland, were utilized. Radiocarbon dating of five samples, stable isotope analysis of carbon and nitrogen in two samples, and strontium isotope analysis in 20 cremated human remains and 12 plant samples were conducted. Radiocarbon dating confirmed the earlier dating of the site to the period between approximately 80 and 260 CE. Dietary studies indicated that the individuals buried here regularly consumed millet (mean δ13C = –17.8) and animal protein (mean δ15N = 9.5). This diet corresponds with the variability described for the Wielbark culture site in Rogowo. The strontium isotope analysis revealed significant variation between the river valley (0.7157–0.7264) and the adjacent upland (0.7109–0.7138). The isotopic values in humans were homogeneous, ranging from 0.7113 to 0.7130, indicating no outliers that might suggest the presence of migrants. The variability observed in humans corresponds with the values observed on the upland. The results suggest that the group of individuals buried in Grzybnica was a small community that sourced their food from the upland. It is possible that this community was involved in the care of the stone circles, and the circles themselves may have been places of gatherings for local communities. However, it should be noted that only about 20 % of the graves found at the site were analyzed. The lack of migrants may be due to the low mobility of this group or methodological limitations related to the post-glacial nature of the geological substrate. Alternatively, it could also be due to the limitations associated with studying cremated remains, which allow for the reconstruction of events from only about 10 years prior. [ABSTRACT FROM AUTHOR]

The study of fish movement patterns in freshwater ecosystems remains a major focus of contemporary research. Small freshwater fish are known to migrate between tributaries and mainstems at different stages of their life history, helping to avoid local extinctions and maintain genetic diversity. However, fitting small fish species with telemetry equipment is difficult, making it challenging to track their detailed migration history via conventional methods. We evaluated the suitability of otolith isotope analysis for verifying the migration histories of small fish species inhabiting small tributaries. In this study, we compared the 87Sr/86Sr values in stream water and the otoliths of two fish species (Nipponocypris temminckii and Rhinogobius flumineus) inhabiting small streams. The 87Sr/86Sr ratios in the stream waters within the study area displayed considerable variation among tributaries. Our findings indicate that only N. temminckii has high dispersal ability, showing movement between tributaries or between tributaries and the mainstem in some locations. In contrast, such movement was not generally observed for R. flumineus. These results show the potential of 87Sr/86Sr as a tool for estimating the migration patterns of small fishes that inhabit small tributaries. [ABSTRACT FROM AUTHOR]

Developments of detrital zircon geochronology have resulted in an explosion of publications that report or discuss detrital zircon data. Combined detrital zircon U–Pb ages with Hf isotope analyses from modern and Quaternary sediments have been widely carried out with the aim of characterizing continental crustal evolution and tracing sediment provenance. Although several detrital zircon databases have compiled U–Pb and Hf data on global scale, the dataset of detrital zircon with a special focus on modern sediment has rarely been compiled. Here, we publish a new detrital zircon dataset of modern and Quaternary sediments in China with 59,535 U–Pb ages and 4,971 Hf isotope data, with detailed information of isotope ratios, ages, Th/U, etc. Four types of sediments have been classified according to sedimentary environments, including fluvial, marine, aeolian and alluvial sediments. Preliminary analysis is carried out on these compiled data to provide new insights into sedimentary provenance and crustal evolution in China. Eight age populations are identified corresponding to tectonic–thermal or magmatic events, including 2,300–2,700 Ma, 1,800–2,000 Ma, 700–1,000 Ma, 400–500 Ma, 200–300 Ma, 120–200 Ma, 80–120 Ma and < 60 Ma. Accompanying with quantitative comparison between sediments from various sedimentary environments, these U–Pb age distributions reveal the provenance link between "source" and "sink" in both exorheic and endorheic drainages. The compiled εHf(t) data reflect that the crustal history of China is apparently episodic, whose pattern is similar to that of global record. Further work will be implemented for database construction, including the integration of latest literatures, AI‐based data extraction and data aggregation. [ABSTRACT FROM AUTHOR]

The Rochechouart impact structure in the northwestern part of the French Massif Central (FMC) has a great diversity of impactites, including monomict impact breccias, suevite, and impact melt rocks (IMRs). The structure is strongly eroded, which allows the study of impactites of the crater fill and the transition into the crater floor. The FMC has had a multistage geological evolution from the late Neoproterozoic to the Ordovician (600–450 Ma) until the later stages of the Variscan orogeny (~300 Ma). Previous geochronological work on Rochechouart has been focused mainly on the impactites and constraining the impact age, and scarce work has been done on the FMC‐related target rocks. Here, U‐Pb isotope analysis by LA‐MC‐ICP‐MS has been conducted on zircon from two IMRs from the Recoudert and Montoume localities, and from a monzodiorite, a paragneiss, and two amphibolite samples of the basement to the impact structure. Zircon from the target rocks yielded mainly Neoproterozoic to Carboniferous ages (~924 to ~301 Ma) that can mostly be correlated to different stages of the geological evolution of the FMC. The monzodiorite also yielded a Permian age of 272 ± 12 Ma. Zircon from the IMRs, and especially from the Montoume sample, gave a comparatively higher diversity of Neoproterozoic to Jurassic ages (~552 to ~195 Ma). Provenance analysis for the zircon age populations of the impactites compared to those of the basement rocks shows overall poor correlation between the two age groups. This suggests that other target lithologies were involved in the formation of these impact melts as well. Post‐Variscan and preimpact ages (281–226 Ma) obtained for both melt rocks probably reflect a previously unconstrained event in the evolution of the regional geological history. Ages similar to the currently most widely accepted impact age of ~204–206 Ma were obtained from both IMR samples. In addition, the Montoume melt rock yielded several post‐204 Ma ages, which might reflect a to date unconstrained, about 194 Ma postimpact thermal/hydrothermal event. [ABSTRACT FROM AUTHOR]

The study examined the effects of three pretreatments, blanching (5, 10, and 30 min), ultrasound (15, 20, and 30 min), and steam blanching (10, 20, and 30 min) on sugarcane, assessing their impact on sugarcane juice quality parameters and aroma compounds. The control had the highest soluble solid content, while the ultrasound‐15 min (US‐15 min)‐treated sample had the lowest, affecting pH, total acidity, and color values significantly. Color analysis showed lower L* values and less greenish tones in treated samples. The implemented pretreatments effectively reduce the browning index, with the US‐20 min treatment showing the most significant reduction compared to the control sample. All pretreatments deactivated polyphenol oxidase. Carbon isotope analysis yielded significant results. Principal component analysis and hierarchical clustering linked 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) with 2,2′‐azino‐bis 3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) and 5‐hydroxymethyl furfural (HMF) with total phenolic content. The study also highlights significant variations in aroma compound profiles among pretreated sugarcane juice samples, with blanching for 10 min showing notable increases in specific compounds like 2‐heptanone and nonanol. Hierarchical clustering showed similarities between blanching‐30 min and US‐30 min, contrasting with the control. Blanching‐10 min had a positive impact on sugarcane juice quality. In conclusion, the study emphasized how pretreatments affect physicochemical properties and aroma compounds in sugarcane juice. Practical Application: The research findings suggest that blanching and ultrasound pretreatments can be used by the food industry to improve sugarcane juice quality by reducing browning, enhancing color, and altering aroma profiles. These pretreatments could extend the shelf life and appeal of sugarcane juice, making it more attractive to consumers while maintaining its nutritional properties. [ABSTRACT FROM AUTHOR]

This study presents the development, validation and use of an approach for precise and accurate cadmium (Cd) isotopic analysis at low concentration levels using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). The MC-ICP-MS unit used was equipped with a standard sample introduction system, thus using an ICP operated under wet plasma conditions, and Faraday cup amplifiers equipped with a 1013 Ω resistor. One-column anion exchange chromatography allowed isolation of Cd with 80-99% recovery and absence of an effect of potential on-column fractionation on the isotope ratio results was demonstrated. Use of both an internal (using Ag) and an external (measured in a sample-standard bracketing sequence) standard was relied on for correction of the bias introduced by instrumental mass discrimination. A long-term precision of 0.09& (2SD) for δ114/110Cd was achieved at a Cd concentration of 10 ng mL-1. The method developed was validated by analysing NIST SRM 2711a (Montana soil) and NRC TORT-3 (Lobster hepatopancreas) reference materials, yielding results consistent with literature values. Subsequently, the method was applied to two Antarctic marine organisms Adamussium colbecki and Trematomus bernacchii, collected during both the 1990s and 2020s, to investigate its potential for identifying changes in the biogeochemical cycle of Cd over time and reveal natural or anthropogenic sources. A preferential uptake of the lighter Cd isotopes in both species was observed, indicated by negative δ114/110Cd values ranging between -0.24 and -0.09&. This finding is consistent with previous studies that have reported Cd fractionation during its uptake by marine organisms, with a preference for the lighter isotopes. No significant differences in δ114/110Cd values were observed between organs of the same species or between the same species collected in the different decades, suggesting minimal Cd isotope fractionation during internal transfer and consistent Cd sources over time. Comparison with literature data suggests that the Cd source in Antarctic biota may be predominantly of natural origin, with δ114/110Cd values indicating isotopically heavier Cd than that found in Cd-polluted areas. However, further Cd isotope ratio data from various Antarctic sample types are necessary to further evaluate the Cd sources in marine samples. [ABSTRACT FROM AUTHOR]

In situ U-Th-Pb geochronology of monazite is widely used to reveal geological histories. Well characterized matrix-matched reference materials are crucial for achieving accurate results in microbeam U-Th-Pb dating. In this paper, the internal structure, chemical composition and U-Th-Pb dates of M6 monazite are investigated using multiple analytical methods to evaluate its potential as a reference material for in situ monazite U-Th-Pb dating. The results show that M6 monazite has an average ThO2 content of 10.7 ± 1.1% (2SD; SD = standard deviation) and Th/U ratio of 28.4 ± 3.3 (2SD). In situ U-Th-Pb dates from laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and secondary ion mass spectrometry (SIMS) laboratories are reproducible and homogeneous at the spatial level of 30 μm. Seven 207Pb/235U dates from isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) yield a mean date of 485.7 ± 2.3 Ma (2SD), which is our recommended date for M6 monazite. Furthermore, SIMS oxygen isotope determinations show good measurement reproducibility (7.70& ± 0.41&, 2SD) and the LA-MC-ICP-MS analyses yield homogeneous Sm-Nd isotopic composition (143Nd/144Nd = 0.511829 ± 0.000045, 2SD; 147Sm/144Nd = 0.2302 ± 0.0139, 2SD), demonstrating that M6 monazite has the potential to be a reference material for in situ O and Sm-Nd isotopic analyses. [ABSTRACT FROM AUTHOR]

In this work, a highly sensitive Nd isotopic analysis method by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) with ultrasound nebulization-dielectric barrier discharge (UNDBD) vapor generation as sample introduction is developed. The sensitivities of Nd isotopes determined by UNDBD are enhanced about 4.5 fold and 1.5 fold compared to conventional wet plasma and dry plasma, respectively, attributed to the generation of volatile Nd species during the dielectric barrier discharge (DBD) induced vapor generation process. Fractionation of Nd isotopes in UNDBD exhibits a massdependent characteristic, enabling successful correction of the 143Nd/144Nd ratio using the 146Nd/144Nd ratio with an exponential law. The minimum Nd concentration and volume required per analysis by UNDBD-MC-ICP-MS can be as low as 0.5 μg L-1 and 600 mL, thereby minimizing the sampling volume for Nd isotopic analysis in open seawater to 0.7 L. Interferences from residual major ions in seawater, present at mg L-1 level after pretreatment, are found to be negligible for Nd isotopic analysis by UNDBD-MC-ICP-MS. The long-term external precision (2RSD) for 143Nd/144Nd with 1 μg L-1 of Nd using this method is calculated as 64 ppm. The accuracy of 143Nd/144Nd determined by this method has been successfully validated by Nd isotopic standard solutions of GSB 04-3258-2015 and GBW04440. The Nd isotopic ratios determined in several seawater samples by UNDBD are in agreement with results obtained by the dry plasma method. UNDBD demonstrates both higher sensitivity and precision for Nd isotopic analysis compared to wet plasma and dry plasma sample introduction methods, making it more suitable for analyzing open seawater samples with low Nd concentrations and less sampling volume. [ABSTRACT FROM AUTHOR]

Recent developments in spatially-resolved boron isotopic analysis using laser ablation as ameans of sample introduction to MC-ICPMS instruments (LA-MC-ICPMS) increasingly allow researchers to explore the spatial heterogeneity of the boron isotopic composition of a range of geochemical applications, for example in palaeoclimatology and mantle petrology. However, previous work has shown that a diffuse interference centred near 10B, when measuring samples with a calcium-rich matrix, can significantly bias especially the measurement on 10B, affecting the accuracy of boron isotope measurements. Although several correction approaches have yielded sufficiently accurate analyses of d11B in calcium carbonate, the root cause of this interference is still not fully resolved. Here, we explore the various potential sources of inaccuracy in boron isotope measurements made using (LA-)MC-ICPMS by experimenting with dry and wet plasma conditions, in both solution and laser ablation mode (in the former case, our solution (Ca-Mg)/B ratios broadly mimic those found in natural samples). In solution mode, we find that irrespective of wet or dry plasma conditions, the introduction of a Ca-containing matrix yields a baseline up to ~4 and ~14 times higher around m/z z 10 for wet and dry plasma conditions, respectively, compared to both a Mg-only matrix and lack of matrix. In order to explore this further, we performed mass scans around m/z z 10 during laser ablation of different carbonates with varying matrix [Ca]. These show that the m/z z 10 interference scales linearly with a mixture of the calcium content of the analyte matrix and 40Ar4+ ion beam intensity, as previously hypothesised. Moreover, by experimenting with different plasma loading scenarios during the ablation of CaCO3, i.e. varying laser spot sizes, we find that permil-level inaccuracies in d11B may occur when the analyte ablated mass is significantly different than that of the standard used to calibrate instrumental mass bias. This is important given that we also show that different commonly-used reference materials ablate at very different rates, which illustrates the need for a careful standardisation approach irrespective of broader matrix effects when sub-permil level accuracy and precision are desirable when utilising LA-MC-ICPMS. [ABSTRACT FROM AUTHOR]

The Yangtze Craton is one of the crucial cratons constitued the eastern Asia continent. It is characterized by Archaean to Paleoproterozoic basement rocks, making it an excellent area to study the Precambrian geologic and tectonic regime. Recently, abundant Archaean rocks have been reported from the Dabie Orogen, which providing important information to understanding the early evolution of the Northern Yangtze Craton. In this contribution, we present petrological, whole-rock geochemical, and zircon U – Pb – Hf isotopic analyses on newly discovered Neoarchean granite in the Dabie Orogen. We identified 2744 ± 10 Ma and 2715 ± 11 Ma (~2.74 Ga) Na-rich granitic gneisses, 2691 ± 6 Ma and 2696 ± 8 Ma (~2.69 Ga) A2-type granitic gneisses, and 2664 ± 8 Ma, 2664 ± 6 Ma, 2672 ± 7 Ma, 2642 ± 10 Ma (~2.66 Ga) A1-type granitic/syenite gneisses from the Daqishan area of the Dabie Orogen. Geochemical and zircon Hf isotope data indicate that the ~ 2.74 Ga Na-rich granitic gneisses were partial melting products of thickened mafic crust with limited depleted mantle input, while the 2.69 Ga and 2.66 Ga A-type granitic gneisses represent felsic magmatism in a post-collisional to an extensional tectonic setting. Based on our research, we categorized the Northern Yangtze Craton into the Kongling domain and Dabie domain by comparing with the distribution of the zircon U-Pb magmatic ages and metamorphic events. We suggest that the initial unified basement of the northern proto-Yangtze Craton formed during the Nuna supercontinent cycle at ~ 2.0 Ga. [ABSTRACT FROM AUTHOR]

Tellurium (Te)-bearing adularia-sericite epithermal Au-Ag deposits are widely distributed in calc-alkaline magmatic arcs and are an important current and future source of precious and critical metals. The source of ore-forming fluids in these deposits remains unclear due to the lack of in situ isotopic evidence on Au-, Ag-, and Te-bearing minerals. To advance the understanding of the source and evolution of Te and precious metals, herein, we combine in situ Pb isotope analysis with He, Ne, and Ar isotope and microthermometric analysis of fluid inclusions in ore and gangue minerals from two Te-rich and two Te-poor epithermal Au-Ag deposits that occur in an Early Cretaceous magmatic arc in the North Heilongjiang Belt, northeastern China. Ore minerals (hessite, petzite, calaverite, altaite, pyrite, chalcopyrite, and galena) from Te-rich Au-Ag deposits, including Sandaowanzi and Yongxin, have the least radiogenic Pb isotope compositions (206Pb/204Pb from 18.1 to 18.3) and the lowest μ1 values (the 238U/204Pb ratio of the lead source down to 9.14) of the deposits studied. For these Te-rich deposits, noble gas isotope data show that fluid inclusions in ore minerals contain a large proportion of mantle He (up to 25%), whereas barren early-stage minerals do not (<1%). The Pb, noble gas isotope, and fluid inclusion microthermometric results suggest that Te-rich ore-forming fluids were likely discharged from mafic magmas into convecting meteoric flow systems at shallow levels (<2 km). In contrast to the Te-rich deposits, ore minerals from the Te-poor Dong'an Au-Ag deposit have radiogenic Pb isotope compositions (206Pb/204Pb from 18.8 to 18.9) and the highest μ1 values (up to 10.54). Fluid inclusions in ore minerals contain a small proportion of mantle He (1% to 5%). The results suggest that metals and ore-forming fluids in these deposits were discharged from either more crustally contaminated intermediate-felsic magmas or leached from upper crustal rocks by convecting meteoric flow systems. Although the Te-poor Tuanjiegou Au-Ag deposit has a non-radiogenic Pb isotope composition consistent with a mafic magma source, Te is much less abundant (electrum [>95%] is the major gold- and silver-bearing mineral) than Au. The main exploration implication of these results is that unexplored volcano-plutonic centers in the northeast Xing'an Block with less radiogenic Pb isotope compositions (206Pb/204Pb < 18.3) and containing fluids with a high proportion of mantle He are more likely to generate Te-rich epithermal Au-Ag deposits than other volcano-plutonic centers in NE China. [ABSTRACT FROM AUTHOR]

The availability of lithium resources is of great significance for the development of modern technologies, as well as for civil and military industries. The Qinghai-Tibet Plateau is a region known for its abundance of lithium-rich salt lakes. However, the specific origin of lithium in these lakes is still unknown, which hinders the advancement of the lithium resource business in this region. To research this issue, this study involved the collection of 20 samples from Lakkor Co Salt Lake on Qinghai-Tibet Plateau, encompassing samples of surface brine, cold springs, fresh lakes, and recharge rivers. The composition of anions and cations in these samples was determined. Furthermore, the analysis extensively utilized the Piper three-line diagram, Gibbs model, and ion proportion coefficient. The findings of this study indicate that as the moves from the recharge water system to salt lake, there is a transition in water type from strong carbonate to moderate carbonate and weak carbonate, as well as Na sulfate. This research based on a similar source of both lithium and boron, utilized ion correlation analysis and boron isotope study in the Lakkor Co area, and analyzed the source and transporting process of lithium. The main origin of lithium in Lakkor Co is the dissolution of lithium-rich rocks, recharge water systems, and deep hydrothermal fluids. These findings are highly significant in enhancing the foundational data of lithium-rich brine resources in the Qinghai-Tibet Plateau and are beneficial for assessing the future development of such deposits. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the potential of compound‐specific isotope analysis of amino acids (CSIA‐AA) for investigating infant feeding practices, we conducted a long‐term study that compared infant and maternal amino acid (AA) nitrogen isotope ratios. Materials and Methods: Fingernail samples were collected from a single mother–infant dyad over 19 months postpartum. Carbon and nitrogen stable isotope ratios were measured in the bulk keratin of the fingernail samples. Selected samples were then hydrolyzed and derivatized for compound‐specific nitrogen isotope analysis of keratin AAs. Results: As in previous studies, infant bulk keratin nitrogen isotope values increased during exclusive breastfeeding and fell with the introduction of complementary foods and eventual cessation of breastfeeding. Infant trophic AAs had elevated nitrogen isotope values relative to the mother, while the source AAs were similar between the mother and infant. Proline and threonine appeared to track the presence of human milk in the infant's diet as the isotopic composition of these AAs remained offset from maternal isotope values until the cessation of breastfeeding. Discussion: Although CSIA‐AA is costly and labor intensive, it appears to hold potential for estimating the duration of breastfeeding, even after the introduction of complementary foods. Through the analysis of a full suite of AAs, it may also yield insights into infant physiology and AA synthesis. [ABSTRACT FROM AUTHOR]

Buziwannan granodiorite and monzogranite associated with gold–polymetallic mineralization are located in the West Kunlun Orogen Belt in northwest China. Granodiorite was emplaced earlier than monzogranite. To determine the genesis of plagioclase from two intrusions and their relation with mineralization, the major, trace elemental, and Sr isotopic compositions of plagioclase were determined through LA-ICP-MS and LA-MC-ICP-MS respectively. The results indicated that the plagioclase from granodiorite had a high-An (around 40%) core and low-An (around 33%) rim, while the plagioclase from monzogranite was uniform with an An value around 18%. The (87Sr/86Sr)i ratios of plagioclase decreased with decreasing An value, which may be caused by small-scale crustal contamination and/or magma mixing. The crystallization process of plagioclase is mainly accompanied by the exsolution of magmatic H2O, and the pressure changes caused by the loss of magma H2O. These magmatic fluids are rich in ore-forming elements, such as Au–Ag–Cu–Zn, and form skarn mineralization near the wall rocks. Because of the co-crystallization of plagioclase, hornblende, and biotite, as well as the addition of minor felsic magma with lower Sr isotopic composition, the plagioclase from monzogranite exhibits low and uniform An values. In addition, a large amount of magmatic H2O carrying ore-forming elements was released during the emplacement of granodiorite, which caused the monzogranite to lose its metallogenic potential. [ABSTRACT FROM AUTHOR]

Summary: Even though they share many thematical overlaps, plant metabolomics and stable isotope ecology have been rather separate fields mainly due to different mass spectrometry demands. New high‐resolution bioanalytical mass spectrometers are now not only offering high‐throughput metabolite identification but are also suitable for compound‐ and intramolecular position‐specific isotope analysis in the natural isotope abundance range. In plant metabolomics, label‐free metabolic pathway and metabolic flux analysis might become possible when applying this new technology. This is because changes in the commitment of substrates to particular metabolic pathways and the activation or deactivation of others alter enzyme‐specific isotope effects. This leads to differences in intramolecular and compound‐specific isotope compositions. In plant isotope ecology, position‐specific isotope analysis in plant archives informed by metabolic pathway analysis could be used to reconstruct and separate environmental impacts on complex metabolic processes. A technology‐driven linkage between the two disciplines could allow us to extract information on environment–metabolism interaction from plant archives such as tree rings but also within ecosystems. This would contribute to a holistic understanding of how plants react to environmental drivers, thus also providing helpful information on the trajectories of the vegetation under the conditions to come. [ABSTRACT FROM AUTHOR]

Many coastal and island communities depend on groundwater as the only source of freshwater, making it an invaluable resource. In the Mediterranean region, groundwater resources are highly vulnerable to natural and anthropogenic pressures, such as overexploitation, climate change, seasonal variations in precipitation, and seawater intrusion. Hence, an understanding of hydrogeological processes and groundwater chemistry is a basis for the sustainable management of coastal and island groundwater resources. Vis, a small and remote karst island in the Adriatic Sea, exhibits peculiar geological and hydrogeological settings, resulting in the island's autonomous water supply. The current pumping capacity (maximum of 42 l/s) meets most of the demand, but intensive summer tourism and climate change exert high stress on groundwater resources during the dry season. Consequently, in the last decade, occasional reductions for consumers occurred. Monitoring of in situ physicochemical parameters and groundwater sampling for chemical and isotopic analyses were conducted from 2020 to 2023 at deep borewells, shallow dug wells, and springs. Hydrochemical interpretation indicated that groundwater chemistry was affected primarily by carbonate and sulfate rock dissolution, mixing with seawater, reverse ion exchange, and dedolomitization. The majority of groundwater samples exhibit Ca–HCO3 hydrochemical facies, followed by Na–Cl and mixed facies. The low percentage of seawater in the mixture indicated that seawater intrusion is not too extensive even during prolonged dry periods, implying a favorable hydrostatic regime with relatively small but sufficient groundwater reserves of the island's aquifers, although the investigated period was characterized by significantly lower precipitation with respect to the 30-year average. [ABSTRACT FROM AUTHOR]

Deep subsurface microorganisms constitute over 80 % of Earth's prokaryotic biomass and play an important role in global biogeochemical cycles. Geochemical processes driven by geothermal heating are key factors influencing their biomass and activities, yet their full breadth remains uncaptured. Here, we investigated the microbial community composition and metabolism in microbial-natural-gas-bearing aquifers at temperatures ranging from 38 to 81 °C , situated above nonmicrobial-gas- and oil-bearing sediments at temperatures exceeding 90 °C. Cultivation-based and molecular gene analyses, including radiotracer measurements, of formation water indicated variations in predominant methanogenic pathways across different temperature regimes of upper aquifers: high potential for hydrogenotrophic–methylotrophic, hydrogenotrophic, and acetoclastic methanogenesis at temperatures of 38, 51–65, and 73–81 °C , respectively. The potential for acetoclastic methanogenesis correlated with elevated acetate concentrations with increasing depth, possibly due to the decomposition of sedimentary organic matter. In addition to acetoclastic methanogenesis, in aquifers at temperatures as high as or higher than 65 °C , acetate is potentially utilized by microorganisms responsible for the dissimilatory reduction of sulfur compounds other than sulfate because of their high relative abundance at greater depths. The stable sulfur isotopic analysis of sulfur compounds in water and oil samples suggested that hydrogen sulfide, generated through the thermal decomposition of sulfur compounds in oil, migrates upward and is subsequently oxidized with iron oxides present in sediments, yielding elemental sulfur and thiosulfate. These compounds are consumed by sulfur-reducing microorganisms, possibly reflecting elevated microbial populations in aquifers at temperatures as high as or higher than 73 °C. These findings reveal previously overlooked geothermal-heat-driven geochemical and microbiological processes involved in carbon and sulfur cycling in the deep sedimentary biosphere. [ABSTRACT FROM AUTHOR]

The purpose of the study is to compare the results of the stable isotope analysis (δ18O, δ2H, and deuterium excess values) of parallel and synchronous ice wedges exposed in one outcrop in the upper part of the Batagay Yedoma (67.58° N, 134.77° E) and to estimate their precision, that is, a measure of similarity of independent isotope results of two ice wedges. Detailed sampling of two syngenetic ice wedges (IW‐17 and IW‐20) for isotope analysis was carried out in the exposure of the thermo‐erosional ravine in the southeastern part of the Batagay megaslump. In total, results of 105 measurements for IW‐17 and 59 measurements for IW‐20 were obtained. According to 14C AMS ages of organic microinclusions in the ice‐wedge ice, the studied ice wedges began to form no later than 42 cal ka BP. The termination of their growth was dated to about 11.7 cal ka BP. For both ice wedges, generally low isotope values were obtained. For the IW‐17, the mean values are −34.38‰ for δ18O, −264.82‰ for δ2H, and 10.2‰ for dexc. For IW‐20, the mean isotope values are −34.09‰ for δ18O, −262.91‰ for δ2H, and 9.84‰ for dexc. Statistical tests showed significant correlations between the isotope data in the upper parts of ice wedges that may be explained by similar conditions during their growth at this stage. Our results allow us to refine the solutions to the two main issues studied of the Late Pleistocene Yedoma: the age of the ice wedges, the accuracy of the isotope profiles, and the paleotemperature interpretation of the isotope records. [ABSTRACT FROM AUTHOR]

Migratory waterfowl are a harvested resource shared among multiple European countries, exposing them to potential overexploitation. Management of take is challenging since the life cycle of migratory waterfowl consists of several stages distributed among several locations, with possible spatio-temporal overlap among populations with differing population trends. Successful harvest management in such situations requires knowledge about the connections between breeding and non-breeding locations, and where birds are harvested. Breeding populations of Eurasian wigeon (Mareca penelope) are declining in Finland, underlining the need for more effective harvest management. Relative proportions and temporal distribution of local breeding birds and migrants from a larger Russian breeding population within the Finnish hunting bag has been unknown to date. We studied spatio-temporal origins of Finnish harvested wigeon by measuring stable-hydrogen (δ2H) isotope values from legally harvested birds. We modelled the changes in δ2H values of the feather samples within the hunting season using Gaussian processes and found that the origin of harvested wigeon in Finland changed during the hunting season and differed by age and sex. In juveniles and adult females but not in adult males, origin of harvested birds shifted from local and possibly western Russian birds to more long-distance migratory birds during the harvest season. These patterns likely reflected sex- and age-specific differences in migratory behaviour of Eurasian wigeon in the East Atlantic flyway, which can be used to guide future management and conservation of this species through the implementation of spatio-temporal harvest regulation. [ABSTRACT FROM AUTHOR]

Summary Understanding isotope fractionation mechanisms is fundamental for analyses of plant ecophysiology and paleoclimate based on tree‐ring isotope data. To gain new insights into isotope fractionation, we analysed intramolecular 13C discrimination in tree‐ring glucose (Δi′, i = C‐1 to C‐6) and metabolic deuterium fractionation at H1 and H2 (εmet) combinedly. This dual‐isotope approach was used for isotope‐signal deconvolution. We found evidence for metabolic processes affecting Δ1′ and Δ3′, which respond to air vapour pressure deficit (VPD), and processes affecting Δ1′, Δ2′, and εmet, which respond to precipitation but not VPD. These relationships exhibit change points dividing a period of homeostasis (1961–1980) from a period of metabolic adjustment (1983–1995). Homeostasis may result from sufficient groundwater availability. Additionally, we found Δ5′ and Δ6′ relationships with radiation and temperature, which are temporally stable and consistent with previously proposed isotope fractionation mechanisms. Based on the multitude of climate covariables, intramolecular carbon isotope analysis has a remarkable potential for climate reconstruction. While isotope fractionation beyond leaves is currently considered to be constant, we propose significant parts of the carbon and hydrogen isotope variation in tree‐ring glucose originate in stems (precipitation‐dependent signals). As basis for follow‐up studies, we propose mechanisms introducing Δ1′, Δ2′, Δ3′, and εmet variability. [ABSTRACT FROM AUTHOR]

Simple Summary: In this contribution, we show that, at a natural abundance, the nitrogen, carbon, and sulfur isotopic compositions of uterus cancerous and healthy tissues are different due to various metabolic pathways. These differences indicate that the isotopic composition might be a potential diagnostic and prognostic biomarker. We have tried to correlate the isotopic composition of tissues with that of serum, which would give us access to noninvasive biomarkers. In this respect, the obtained bulk isotopic compositions do not show any systematic correlation between the cancerous tissue and serum. Their application as biomarkers would probably require a position-specific isotopic analysis. Objectives: The metabolic pathway of cancerous tissue differs from healthy tissue, leading to the unique isotopic composition of stable isotopes at their natural abundance. We have studied if these changes can be developed into diagnostic or prognostic tools in the case of endometrial cancer. Methods: Measurements of stable isotope ratios were performed using isotope ratio mass spectrometry for nitrogen, carbon, and sulfur isotopic assessment. Uterine tissue and serum samples were collected from patients and the control group. Results: At a natural abundance, the isotopic compositions of all three of the studied elements of uterus cancerous and healthy tissues are different. However, no correlation of the isotopic composition of the tissues with that of serum was found. Conclusions: Differences in the isotopic composition of the tissues might be a potential prognostic tool. However, the lack of a correlation between the differences in the isotopic composition of the tissues and serum seems to exclude their application as diagnostic biomarkers, which, however, might be possible if a position-specific isotopic analysis is performed. [ABSTRACT FROM AUTHOR]

The Eastern Zhou period of China, characterised by complex interactions among vassal states, witnessed significant advancements in bronze production technology. However, the investigation of interactions based on technological comparison among dominant and dependent states remains limited. Focusing on two newly excavated foundry sites, Baidian in Houma, Shanxi, and Xincun in Hebi, Henan, this study provides crucial insights into the bronze production technologies and material sources used by Jin, a major vassal state in Central China, and Wei, a dependent state of Jin, during the Eastern Zhou period. Elemental analysis and microstructural examinations of slags, fragments of crucible wall and furnace wall, show the diversity of bronze production techniques between these two sites: in the Baidian site, bronzes were predominantly produced by co-melting of metallic copper and tin, and remelting of recycled bronzes, whereas in the Xincun site, bronze were probably made by co-melting of copper and tin ore. Furthermore, lead isotope analysis results suggest that the lead materials used for the bronze production at both the sites were likely from the Xiaoqinling region. Integrated with the historical background of complex interactions among vassal states, these findings not only shed light on the technological advancements and resource networks of the Jin and Wei states but also explain the relationships between technology, resources and social dynamics from various perspective. Hopefully this research would promote archeometallurgical study among regions and be applied to other Bronze Age cultures in the world. [ABSTRACT FROM AUTHOR]

The southeast edge of the Loess Plateau (SELP) is a crucial area for studying subsistence strategies and social complexity in prehistoric China. Currently, no systematic isotopic study has been conducted to reveal shifts in subsistence strategies and their link to the trajectory of social complexity. This paper compiles previously published isotopic data from human and fauna bones at 24 sites dating from 8000 to 5000 BP, aiming to uncover diachronic changes in subsistence strategies and their relationship with social complexity. The results indicate a gradual increase in millet consumption by humans and an increasing utilization of millet‐based byproducts as feed for domestic animals (pigs and dogs) over time. The isotopic data of humans and animals demonstrate the establishment of millet agriculture during the Early Yangshao period (7000–6000 BP). Millet agriculture creates a crucial material foundation for population growth and cultural prosperity. Two modes of millet cultivation, intensive and extensive, are proposed to explain the continuous development of millet agriculture since the Early Yangshao period. Finally, significant dietary heterogeneity among the human population during the Late Yangshao period strongly suggests the emergence of social differentiation and complexity, supported by other archaeological evidence such as settlement hierarchies and the presence of exquisite objects in burials. [ABSTRACT FROM AUTHOR]

The highly evolved granites are closely associated with rare-metal mineralization. It is still debated whether the enrichment of rare metals is mainly controlled by magmatic or hydrothermal processes. Lithium is a fluid-mobile element that preferentially partitions to the fluid phase when the melt reaches H2O saturation, making the Li isotope system a powerful geochemical tool to record the potential melt-fluid interaction during magma evolution. This study addresses the issue of Li isotope fractionation in highly evolved fine syenogranites (FSGs) from the Xintianling pluton in the Nanling Range, South China. The Xintianling pluton consists of the coarse biotite monzogranites (CBMGs) and evolved FSGs. The identical Nd isotope data of the CBMGs (εNd(t) = -8.2–-8.8) and FSGs (εNd(t) = -7.9–-8.9) suggest that they were derived from the same crustal magma. The FSGs were derived from the highly evolved melts extracted from CBMGs through the fractionation of major rock-forming minerals. This is supported by the compositional shifts and validated by Rb, Sr, and Ba trace element modelling. Li isotopic analysis shows that highly evolved FSGs have heavier Li isotope compositions (δ7Li = 2.6–7.9 ‰) than the CBMGs (δ7Li = 0.1–1.9 ‰). Isotopic modelling, coupled with variations in Li concentrations in FSGs, suggests that diffusive kinetic fractionation by disequilibrium fluid exsolution during the late stage of the granitic magma evolution controls the Li isotope fractionation of the Xintianling granites. Rapid fluid exsolution not only modified the Li isotope composition of the FSGs but also transported the rare metals (e.g. W) and fluxing components (Li, F, and Cl), which resulted in the formation of the large Xintianling W deposits. [ABSTRACT FROM AUTHOR]

Introduction: The carbon isotope ratios (δ13C) of essential amino acids (EAAs), including valine, leucine, isoleucine, threonine, and phenylalanine, in producers are crucial for explaining food-web structures in marine ecosystems. However, few studies have tested the variability of δ13C-EAA values in marine macrophytes, such as seagrass and macroalgae, under changing environmental conditions. Methods: In this study, we examined the responses of δ13C-EAA values in macrophytes to environmental changes and explored their usefulness in characterizing macrophyte groups and local environments. We tested seagrass and macroalgae collected at different spatial and temporal scales in the field, as well as lab-cultured Ulva algae at various temperature gradients (12°C, 20°C, and 27.5°C) with additional nitrogen sources. Results: We found that δ13C-EAA values in macroalgae were significantly altered by seasonality and the interactive effects of temperature and nitrogen addition in comparison with mean-centered δ13C-EAA values (normalized δ13C-EAA values relative to the mean of the overall EAAs). The δ13C-EAA values detected in macroalgae within a local environment correlated with those of a cooccurring grazer, Caprella. Based on mean-centered δ13C-EAA values, macrophyte groups were distinguishable from other group (i.e., the bacteria group) even under diverse environmental conditions. Moreover, the seagrass group did not overlap with the green and the brown macroalgal group, but overlapped considerably with the red macroalgal group. Discussion: These results suggest that the macrophyte-specific mean-centered δ13C-EAA values may be fairly consistent across broad spatial and temporal scales. Despite significant variation in δ13C-EAA values, the consistency in meancentered δ13C-EAA values among specific macrophyte groups provides valuable insight into the characteristics of local trophic bases in regions under pressure from dramatic environmental changes. [ABSTRACT FROM AUTHOR]

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3‐6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (~Fa21–22). The physical properties like density (3.34 g cm−3) and magnetic susceptibility (logχ <5.0, with χ in 10−9 m3 kg−1) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near‐surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock‐darkened fragments, and (e) clasts of various types of impact melts but no solar wind‐implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had a preatmospheric radius of 25–40 cm, is ~17–20 Myr. [ABSTRACT FROM AUTHOR]

The Mengshan granitoid complex is located in the central part of Jiangnan Orogen and belongs to the western part of Jiangxi Province, where several phases of granitic magmatism record the crustal evolution of the late-Indosinian. However, its petrogenesis remains uncertain, largely due to controversies over its origin, evolutionary process and tectonic setting during intrusion. In this study, the lithological features and contact relationships observed in the systematic field geological investigations indicate that the late magmatic phases of the Mengshan granitoid complex are mainly composed of medium–fine-grained biotite monzogranite and fine-grained monzogranite, both of which developed primary fine-grained muscovite. Petrological, petrographic, geochemical and zircon U-Pb-Hf isotopic studies were further carried out on these rocks. Zircon U-Pb isotopic analyses suggest that the medium–fine-grained biotite monzogranite mainly formed at 220.7 ± 1.0 Ma to 218.0 ± 0.8 Ma, and that the fine-grained monzogranite formed at 211.5 ± 2.9 Ma to 212.9 ± 1.0 Ma. Whole-rock geochemical analysis results suggest that these rocks are rich in Cs, Rb, and U, and deficient in Ba, Sr, and Ti, and that they have properties characteristic of rocks with high silica, low P content and high K calc-alkali. Mineralogical and geochemical analysis results suggest that they are S-type granites. The εHf(t) values of the early-stage medium–fine-grained biotite monzogranite and late-stage fine-grained monzogranite range from –4.7 to 0.3 and from –3.2 to 0.7, respectively. Geochemical and isotopic data suggest that these granitoids were derived from the partial melting of Proterozoic continent basement rocks, and that minor mantle materials were involved during their generation. The presence of the early Mesozoic Mengshan granitoid complex reflects a reduplicated far-field converge effect of the collision of the North China and South China blocks and the subduction of the Palaeo-Pacific plate into the South China block. The thickening of the Earth's crust facilitated crustal delamination, underplating of mantle-derived magma, and crustal heating, triggering intense partial melting of the lithosphere and magma enrichment. [ABSTRACT FROM AUTHOR]

The late Mesozoic subduction of the paleoPacific plate (Izanagi plate) beneath Eurasia involved complex changes in the direction and angle of subduction, which have been controversial in recent decades. This study investigated Early Cretaceous late kinematic plutons of the Wulian metamorphic core complex that formed in the southern Jiaodong Peninsula. Based on geochemical and Sr-Nd isotopic analyses, we conclude that the granites in the Heshan (122 Ma) and Kuaijishan (118 Ma) plutons are I-type granites that formed in a back-arc extensional environment, and tensile fractures played an important role in the process of magma emplacement. Gravity anomaly inversion revealed the significant role of tension fractures in the uplift of the late kinematic plutons. Analysis of magnetic fabrics showed that the dominant plunging direction of magnetic lineation in the late kinematic plutons is NW-SE (127°–307°), while the plunging direction of the mineral stretching lineation in the wall rock is nearly E-W (102°–282°). We posit that the extensional stress field in the Jiaodong Peninsula underwent a significant transformation during the Early Cretaceous period, specifically from 135 Ma to 122 Ma, when it was dominated by a regional E-W or WNW-ESE extensional stress field. Later, from 122 Ma to 118 Ma, the stress field was controlled by a NW-SE extensional stress field. This variation in the regional stress field in the Jiaodong Peninsula indirectly indicates the changing subduction and slab rollback direction of the paleo-Pacific plate. From 135 Ma to 122 Ma, the paleo-Pacific plate subducted beneath Eurasia along a WNW-ESE direction. However, back-arc extension and slab rollback led to extensive extension in the Jiaodong Peninsula. Subsequently, the subduction direction of the paleo-Pacific plate shifted to the NW, with rollback occurring eastward at a high angle under the Jiaodong Peninsula from 122 Ma to 118 Ma. This shift resulted in extensive magmatism and widespread gold mineralization. The findings of this study offer new insights into the complex geodynamic processes that occurred during the Early Cretaceous period in the region. [ABSTRACT FROM AUTHOR]

Maintaining extracellular potassium (K+) within narrow limits, critical for membrane potential and excitability, is accomplished through the internal redistribution of K+ between extracellular fluid (ECF) and intracellular fluid (ICF) in concert with the regulation of renal K+ output to balance K+ intake. Here we present evidence from high-precision analyses of stable K+ isotopes in rats maintained on a control diet that the tissues and organs involved in the internal redistribution of K+ differ in their speed of K+ exchange with ECF and can be grouped into those that exchange K+ with ECF either rapidly or more slowly ("fast" and "slow" pools). After 10 days of K+ restriction, a compartmental analysis indicates that the sizes of the ICF K+ pools decreased but that this decrease in ICF K+ pools was not homogeneous, rather occurring only in the slow pool (15% decrease, p < 0.01), representing skeletal muscles, not in the fast pool. Furthermore, we find that the dietary K+ restriction is associated with a decline in the rate constants for K+ effluxes from both the "fast" and "slow" ICF pools (p < 0.05 for both). These results suggest that changes in unidentified transport pathways responsible for K+ efflux from ICF to ECF play an important role in buffering the internal redistribution of K+ between ICF and ECF during K+ restriction. Thus, the present study introduces novel stable isotope approaches to separately characterize heterogenous ICF K+ pools in vivo and assess K+ uptake by individual tissues, methods that provide key new tools to elucidate K+ homeostatic mechanisms in vivo. [ABSTRACT FROM AUTHOR]

Pacific Islands present unique challenges for water resource management due to their environmental vulnerability, dynamic climates, and heavy reliance on groundwater. Quantifying connections between meteoric, ground, and surface waters is critical for effective water resource management. Analyses of the stable isotopes of oxygen and hydrogen in the hydrosphere can help illuminate such connections. This study investigates the stable isotope composition of rainfall on O'ahu in the Hawaiian Islands, with a particular focus on how altitude impacts stable isotope composition. Rainfall was sampled at 20 locations from March 2018 to August 2021. The new precipitation stable isotope data were integrated with previously published data to create the most spatially and topographically diverse precipitation collector network on O'ahu to date. Results show that δ18O and δ2H values in precipitation displayed distinct isotopic signatures influenced by geographical location, season, and precipitation source. Altitude and isotopic compositions were strongly correlated along certain elevation transects, but these relationships could not be extrapolated to larger regions due to microclimate influences. Altitude and deuterium excess were strongly correlated across the study region, suggesting that deuterium excess may be a reliable proxy for precipitation elevation in local water tracer studies. Analysis of spring, rainfall, and fog stable isotope composition from Mount Ka'ala suggests that fog may contribute up to 45% of total groundwater recharge at the summit. These findings highlight the strong influence of microclimates on the stable isotope composition of rainfall, underscore the need for further investigation into fog's role in the water budget, and demonstrate the importance of stable isotope analysis for comprehending hydrologic dynamics in environmentally sensitive regions. [ABSTRACT FROM AUTHOR]

Singly charged background argide ions ArH+, ArN+, ArO+, and Ar2+ create strong spectral interferences in elemental and isotopic analysis by inductively coupled plasma mass spectrometry (ICP MS). In this study, we experimentally investigated the behavior of these ions depending on variations in high-frequency plasma power and argon carrier gas flow rate. Theoretical analysis was performed using thermodynamic modeling to predict the behavior of these argide ions on changes in plasma temperature and argon flow rate. Common patterns in the intensity of these major background ions and changes in their formation efficiency at different working parameters of the ICP are noted. A good agreement between the observed experimental dependences and those derived from thermodynamic models is noted. [ABSTRACT FROM AUTHOR]

Zirconium (Zr) isotope has significant potential for tracing magmatic processes, particularly late-stage fractionation involving fluids. However, the fractionation of Zr isotopes between magma and fluid is still unclear. In-situ Zr isotope analyses of zircons from three granite-pegmatite suites in the Tibetan plateau show a wide range of δ94/90Zr values (IPGP-Zr) between −0.23 ‰ and +1.38 ‰, with the highest values in hydrothermally altered zircons from pegmatites. A coupled dissolution-reprecipitation process of zircons in a zircon-undersaturated melts is the most plausible mechanism to explain the strong enrichment of heavy Zr isotopes in hydrothermally altered zircons. During the formation of granitic pegmatite, exsolution of F-Na-Si-bearing fluids can enhance zircon solubility and will significantly remove Zr from the melt. Faster diffusion of 90Zr into the fluid channel will result in preferential accumulation of light Zr isotopes in the fluid, and drive the residual melt towards heavier Zr isotopes under disequilibrium conditions. Later, the reprecipitated zircons will inherit the heavy Zr isotope composition of the melt. Rayleigh fractionation models suggest fluid-melt fractionation factors for Zr isotope of about 0.99911–0.99930. This shows the major controls of fluid on Zr isotope fractionation during crystal-magma-fluid differentiation. Thus Zr isotope can be a powerful tracer of the magmatic-hydrothermal transition. [ABSTRACT FROM AUTHOR]

Author affiliations *Corresponding authors Sulfur isotopes serve as critical tracers for understanding the material sources and cycling in earth science. The in situ sulfur isotope ratio analysis by laser ablation multiple-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) has been a proven important technique, yet the precision and accuracy of measurement are limited by matrix-matched reference materials. In this study, we investigated three new potential reference materials (pyrite NWU-Py, gypsum NWU-Gy and arsenopyrite NWU-Apy) for sulfur isotope ratio analysis by LA-MC-ICP-MS. The ultra-fine powders of pyrite, gypsum and arsenopyrite were synthesized into a solid block using the fast-hot-pressing sintering method (FHP). The reliability of these reference materials was evaluated by large quantities of sulfur isotope measurements by LA-MC-ICP-MS, with mean δ34S values of 3.48 ± 0.26‰ (2SD, n = 787) for NWU-Py, 18.19 ± 0.32‰ (2SD, n = 290) for NWU-Gy, and -0.19 ± 0.32‰ (2SD, n = 383) for NWU-Apy, which are highly consistent with those obtained from isotope ratio mass spectrometry (IRMS). Furthermore, the F-testing and H-index indicate that the three materials have excellent homogeneity of sulfur isotope compositions. Therefore, NWU-Py, NWU-Gy, and NWU-Apy can serve as bracketing matrix-matched reference materials for in situ sulfur isotope measurement by LA-MC-ICP-MS. [ABSTRACT FROM AUTHOR]

Reconstruction of stable potassium isotope composition (41K/39K) in ancient seawater has significant implications for our understanding of the fundamental controls on the long-term stability of Earth's climate and ocean chemistry, but the relevant research is hampered by scarce preservation of seawater K in geological records. Marine halite (NaCl) samples are potentially valuable archives of seawater K isotope signatures because they often contain abundant fluid inclusions directly sourced from evaporated ancient seawater. However, the extremely high Na matrix relative to low K concentrations in halite presents a formidable challenge for K isotope analysis. This study reports a novel and efficient K extraction method that can separate K from a high Na matrix by precipitating K as a sparsely soluble salt using sodium tetraphenylborate (TPB). Development of this method was based on an in-depth understanding of the TPB precipitation reaction and solubility equilibrium of relevant TPB salts. Key parameters, including reaction time, precipitate recovery and rinse, and further K purification for isotope analysis, have been optimized through extensive laboratory experiments. It is demonstrated that this new method can extract small quantities of K down to 20 μg from a large quantity of the NaCl matrix up to 1 gram. In addition, preliminary results show that this new extraction method can be also applied to prepare carbonate samples, which represent another important type of sample pertinent to K isotope research, notoriously difficult to analyze due to their low K concentrations and high Ca matrices. For the first time, this study demonstrates the utility of TPB chemistry in preparing challenging K-poor, matrix-rich samples for high-precision stable K isotope analysis. [ABSTRACT FROM AUTHOR]

In situ microanalysis of the sulfur (S) isotope composition and elemental distribution in sphalerite is important in geochemistry. A matrix-matched reference material is still lacking in situ microanalysis. In this study, a hydrothermal synthesis method combined with hot-press sintering processes was used to synthesize a sphalerite material Sph-LD. A large number of in situ microanalyses, including trace element concentrations and S isotope compositions, were performed on Sph-LD by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to assess the homogeneity. The LA-MC-ICP-MS results are highly consistent and yield a mean δ34S value of +17.11 ± 0.20‰ (2 SD, n = 560), which is analogous with that measured by IRMS. Microanalysis of element concentrations generally agrees with the data of ICP-MS within 10% for trace elements (relative standard deviation < 10%). These results indicate that Sph-LD is suitable to be a matrix-matched reference material available for quantitative analysis of element concentrations and S isotope measurement of sphalerite using LA-ICP-MS and LA-MC-ICP-MS. Meanwhile, the synthetic method introduces a novel concept for the development of standard materials. [ABSTRACT FROM AUTHOR]

The most used international reference material for neodymium isotope ratios is the JNdi-1 standard. The literature reference values were determined using Thermal Ionization Mass Spectrometry (TIMS) with a conventional internal normalization. In nuclear studies, such normalization is not possible for samples after irradiation, as there is no known isotope ratio that can be considered as a reference ratio. Nd isotopic analysis is essential for calculating the burnup of a reactor. To offer reference values without normalization, 61 measurements of the JNdi-1 material were obtained in three different laboratories on four thermal ionization mass spectrometers using the total evaporation method. Acquired measurements were compared to the exponential mass fractionation law demonstrating that the dominant bias comes from isotope fractionation which can be minimized using the total evaporation method. The suggested reference values and associated uncertainties with a coverage factor of 2, which indicates approximate 95% confidence, were calculated using the DerSimonian--Laird procedure (n = 3): 142Nd/144Nd = 1.13966(23), 143Nd/144Nd = 0.511613(50), 145Nd/144Nd = 0.348729(33), 146Nd/144Nd = 0.72329(15), 148Nd/144Nd = 0.242505(95) and 150Nd/144Nd = 0.23780(14). All these ratios are significantly different from those obtained after normalization using 146Nd/144Nd = 0.7219. The new values obtained for the JNdi-1 can be used in nuclear laboratories where the Nd isotope ratios differ from the natural isotopic compositions or when the total evaporation method is used without internal normalization. [ABSTRACT FROM AUTHOR]

Isotope data of key pollutants are needed for source apportionment analysis in natural ecosystems. Isotope data for cadmium (Cd), a rare and dispersed but toxic element, are very limited mainly due to its low contents in the natural environment. In this study, for samples with low Cd content but high organic matter content, a dry ashing pre-treatment method was proposed to effectively enrich Cd to meet the requirements of its isotope analysis (Cd content > 20 ng). This method was applied to soils, sediments, biological tissues, and coal, with a maximum digestion weight of 1.67 g or more. With the assistance of quartz microfiber filter membranes during dry ashing, good Cd recovery (91.6--108.0%) and significant removal of organic matter were achieved. Mass bias was corrected by combining the silver external standard (Ag-doping) method with the sample-standard-bracketing (SSB) method, and Cd isotope measurements were performed under wet plasma conditions (with an accuracy of 0.060‰). Cd isotopic compositions obtained by the dry ashing method were compared with those obtained by the high-pressure bomb digestion method, and the differences ranged from -0.056 to 0.076‰, indicating that the dry ashing with wrapped membranes method did not cause any fractionation of Cd during the sample pre-treatment process. Meanwhile, the tolerance of tin (Sn) and zinc (Zn) elements provided a significant advantage under wet plasma conditions over dry plasma conditions without reducing the tolerance of molybdenum (Mo) and zirconium (Zr). The method developed in this study should enhance the application of Cd isotopes in investigating Cd cycling in primary ecosystems and organisms. [ABSTRACT FROM AUTHOR]

Reservoir construction promotes many environmental impacts, including the enhancement of mercury concentrations in fish. The processes that can influence mercury concentrations in fish in Amazonian reservoirs are still little explored in depth, especially when we consider the possible particularities of the ecosystems in question. This study aims to investigate how mercury concentrations in fish could be influenced by the Tucuruí dam, considering possible changes in their feeding and trophic position according to the dam position (up or downstream). Fish were sampled upstream and downstream of the Tucuruí reservoir, and total mercury (THg) and stable isotopes of carbon and nitrogen (δ15N and δ13C) were measured in muscles. We observed three different Hg bioaccumulation patterns influenced by the dam. These differences occurred due to species trophic niche changes corroborated by the isotope analysis. Higher THg concentrations downstream compared to those upstream ones were only observed for Geophagus proximus. On the contrary, Plagioscion squamosissimus, from downstream, presented lower concentrations than upstream ones. The isotopic niche of these two species presented different changes according to the sampled site. THg biomagnification was higher upstream compared to downstream, considering that the regression slope was approximately two times higher upstream versus downstream. THg concentrations in fish were explained by the differences in their feeding habits according to their location in relation to the dam. The difference in THg biomagnification was able to reflect differences in structure of the food web chain in ecosystems under the dam's influence. [ABSTRACT FROM AUTHOR]

Abstract Explicit identification of hydrochemical processes and their controlling factors within groundwater systems is critical for the sustainable utilization of water resources in coastal urban areas. This study was undertaken in the North Coastal Region of Jiaozhou Bay (NCRJB), located in the eastern part of Shandong Province, China, an area grappling with significant issues of groundwater quality degradation and water scarcity. A total of 105 groundwater samples and 34 surface water samples, collected from 2020 to 2024, were analyzed and studied using various hydrogeological tools, multivariate statistical analyses, and water quality assessment methods. These include the Piper diagram, hydrochemical facies evolution diagram (HFE-D), Principal Components Analysis (PCA), correlation analysis, stable isotope analysis, Water Quality Index (WQI), and USSL diagrams. The results indicated that all surface water and pore groundwater samples were categorized as Na-Cl type, exhibiting high Total Dissolved Solids (TDS) and Electrical Conductivity (EC) values, characteristics that render them poor to unsuitable for drinking and irrigation purposes. The fracture groundwater is predominantly of the Ca-Na-Cl mixed type, with average suitability for irrigation and a limited proportion (22.5%) deemed suitable for drinking. Seawater intrusion, primarily through the surface water system, and the impact of human activities were identified as the predominant controlling factors con-tributing to the degradation of the local groundwater environment. Field empirical investigations further validated the results derived from hydrogeological assessments, multivariate statistical analyses, and isotopic approaches. The long-term shifts in hydrochemical properties, along with the latent threat of seawater intrusion, exhibit an upward trend during the dry season and show a certain degree of mitigation during the wet season. This study highlights that field investigations, in conjunction with hydrochemical tools, multivariate statistical analyses, and stable isotope analysis, can successfully furnish reliable insights into the predominant mechanisms governing regional groundwater evolution within the context of long-term and intricate envi-ronmental settings.