The stable isotopic values of charred crops are now frequently analysed in archaeology. While previous research has highlighted how grain morphology and stable carbon and nitrogen isotope values ...change with grain charring temperature, such research has been limited to temperature ranges under 260 °C and using predominately Mediterranean cereals and pulses. For the first time, this study provides experimental data on the impact of charring on two northern European cereals, rye and oat, both morphologically and isotopically. New experimental charring of rye, oat, bread wheat and hulled barley extends the charring window to 300 °C, providing an insight into the morphological changes to the grains as well as the difference between charred and uncharred isotopic values. This range of cereals and conditions opens up potential for stable isotopic investigation of medieval agricultural growing conditions and practices in Britain. The results indicate that isotopically, a 0.16‰ and a 0.32‰ offset should be applied to δ13C and δ15N values, respectively, of grains charred between 230 and 300 °C. Morphological and internal structural changes, as well as external distortion, are key attributes which vary with charring temperature and duration. Guidelines are provided to enable assessment of whether archaeological grains of bread wheat, hulled barley, rye and oat fall within the acceptable charring window for isotopic analysis.
•Charring of four cereals to understand morphological and isotopic impact.•Internal and external morphological changes occurred to the charred grains.•Differences between grains' charred and uncharred isotopic values were found.•Offsets recommended for δ13C and δ15N values of grains charred between 230 and 300 °C.•Guidelines provided regarding acceptability of charred grains for isotopic analysis.
Many chlorinated hydrocarbons have gained notoriety as persistent organic pollutants in the environment. Engineered and natural remediation efforts require a monitoring tool to track the progress of ...degradation processes. Compound-specific isotope analysis (CSIA) is a robust method to evaluate the origin and fate of contaminants in the environment and does not rely on concentration measurements. While carbon CSIA has established itself in the routine assessment of contaminated sites, studies incorporating chlorine isotopes have only recently become more common. Although some aspects of chlorine isotope analysis are more challenging than carbon isotope analysis, having additional isotopic data yields valuable information for contaminated site management. This review provides an overview of chlorine isotope fractionation of chlorinated contaminants in the subsurface by different processes and presents analytical techniques and unresolved challenges in chlorine isotope analysis. A summary of successful field applications illustrates the potential of using chlorine isotope data. Finally, approaches in modelling chlorine isotope fractionation due to degradation, diffusion, and sorption processes are discussed.
•Chlorine CSIA enables process and source differentiation.•Successful field applications illustrate the potential of chlorine CSIA.•Isotope fractionation models enable further applications for chlorine CSIA data.•Physical and chemical Cl isotope fractionation processes are detailed.•Methods for measuring Cl isotopic enrichment in contaminants are summarized.
We present a refined approach for acquiring sulfur (S) isotope compositions (33S/32S, 34S/32S) in apatite by secondary ion mass spectrometry (SIMS), including the characterisation of new reference ...materials. In order to test the method, we analyzed potential apatite reference samples for their S isotope ratios via three different bulk methods. The investigated apatite samples contain S concentrations between ~160 μg/g and 3100 μg/g and their 34S/32S (δ34S) ratios deviate by more than 25‰ from the Vienna-Canyon Diablo Troilite (VCDT) standard. We identified four candidates as new primary reference materials for routine SIMS S isotope measurements of apatite. Based on ICP-MS, EA-IRMS, and fluorination analyses, recommended S isotope values are +12.27± 0.22 (2σ) ‰ δ34S for SAP1, +14.02 ± 0.22 (2σ) ‰ δ34S for Big1, −1.06 ± 0.80 (2σ) ‰ δ34S for Durango-A, and −1.39 ± 0.48 (2σ) ‰ for Durango-B. By selecting one of those four primary standards for SIMS analysis, the S isotope values of the other reference materials and additional tested apatite specimens can be reproduced to within 1‰. Under optimized SIMS conditions, single spot uncertainty for δ34S that combines the within-spot precision and the repeatability of measurements of the primary apatite reference material during an analytical session is ±0.4‰ (95% CI). We also show that in apatite with S > 1000 μg/g, SIMS analysis permits the detection of mass-independent S isotope signatures (i.e., Δ33S) that are larger than ~1.0‰ if an average of multiple grains is used, and larger than ~1.5‰ for a single analytical point. Furthermore, our study shows that apatite can record S isotope signatures from extremely diverse environments, making this near-ubiquitous mineral a key candidate for tracing S source reservoirs and to track the pathway of magmatic-hydrothermal fluids in a wide range of geological settings.
The 18O/16O of lignin at bulk, molecular and positional levels can be used to extract valuable information about climate, plant growth environment, plant physiology, and plant metabolism. Access to ...the individual oxygen isotope compositions (δ18O) in the lignin monomeric units is, however, challenging as depolymerization of lignin to release the monomeric units may cause isotope fractionation. We have developed a novel method to measure the δ18O of the three oxygens (O-3, O-4 and O-5) attached to the aromatic ring of the monomeric units (bearing no oxygen in their side chains) releasable by highly selective W2C/AC (tungsten carbide supported by activated carbon)-catalyzed hydrogenolysis of lignin. O-4 is obtained by measuring the δ18O of H-type monomeric unit, while O-3 and O-5 can be calculated following isotope mass balance between H, G and S-type monomeric units measurable simultaneously with GC/Py/IRMS (gas chromatography-pyrolysis-isotope ratio mass spectrometry). The measurement precisions are better than 1.15 mUr and 4.15 mUr at molecular and positional levels, respectively. It was shown that there were a δ18OH > δ18OG > δ18OS isotopic order in the herbaceous plant lignin and an (inclusive) opposite order in woody plant lignin. Such differences in isotopic order is likely to be caused by the fact that both L-tyrosine, which carries an 18O-enriched leaf water signal, and L-phenylalanine, which carries mainly a molecular O2 isotopic signal, serve as the precursors for lignin biosynthesis in herbaceous plants while only the latter serves as precursor for lignin biosynthesis in woody plants. We have highlighted the potential application of such molecular and positional levels isotopic signals in plant physiological, metabolic, lignin biosynthetic and climate studies.
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•Innovative hydrogenolysis of plant lignin was developed to release the H-, G- and S-type monomers, bearing no oxygen in their side chains.•18O/16O ratios were obtained with GC/Py/IRMS for the lignin monomers.•18O/16O ratios for O-3, O-4 and O-5 were obtained by mass balance calculations among three monomers.•Herbaceous plants show an isotope order of δ18OH > δ18OG > δ18OS.•The order is attributable to decreasing contribution of L-tyrosine to H-, G- and S-type lignol biosynthesis.
Bioarchaeological studies provide a valuable contribution to the understanding of the economy and activities of prehistoric populations in mountain regions. The Late Bronze Age in the Caucasus is an ...epoch of fundamental transformations that is accompanied by the development of a semi-stationary pastoral economy and ultimately by the emergence of combined mountain agriculture. So far, only a few archaeozoological assemblages from this period have been published. The site of Ransyrt-1 in the North Caucasus offers a substantial collection of bone material from the remains of a mountain sanctuary. Analysis of the animal remains as well as preliminary isotopic analyses of strontium, oxygen, and carbon shed light on animal exploitation at this site. Comparisons with slightly later settlements in the North and South Caucasus illustrate the development of intensive livestock management strategies in the Late Bronze Age in this region at the interface between Southwest Asia and the Eurasian steppe.
This pilot study addresses the analytical characterisation of 26 well‐known bronze objects of the Early and Middle Bronze Age of Central and Northern Europe. Besides swords and axes of the hoards ...from Apa, Téglás and Hajdúsámson, the investigation includes the famous Sky Disc and its accompanying finds from the Nebra hoard and several full‐hilted swords from Period I in Denmark. In contrast to former publications, the isotopic systematics of lead, tin and copper are the focus of the present investigation. With a combined approach, we try to relate the typologically closely linked or otherwise related artefacts with chemical and isotopic proxies by identifying mixing scenarios. The results demonstrate that artefacts from different locations are most likely not directly linked, but mixing lines across isotope systems suggest a production of the items from common sources by mixing of bronze batches (e.g., bronze ingots), which were probably disseminated between 1600 and 1500 bce. This helps to correlate objects of different locations with each other and to draw conclusions upon typological and cultural connections. Isotopic and chemical correlations of objects within the individual hoards, on the other hand, allow reconstructions of metallurgical practices in single workshops, which, for example, implies recycling of metal scrap.
During the early medieval period in Ireland, Dublin was established as the largest Viking settlement on the island in the ninth century AD. A previous biodistance study has suggested that the ...population of the town consisted of a polyethnic amalgam of immigrant and indigenous. In this study, we use biogeochemistry to investigate paleomobility and paleodiet in archeological human remains from the ninth to eleventh century levels at the sites at Fishamble Street II (National Museum of Ireland excavation number E172), Fishamble Street III (E190) and John’s Lane (E173), as well as twelfth-century remains from Wood Quay (E132). Through radiogenic strontium isotope, stable oxygen, carbon, and nitrogen isotope, and elemental concentration analyses, we investigate the origins of the individuals who lived and died in early and late Viking Dublin. Mean archaeological human enamel and bone isotope values from Dublin are
87Sr/
86Sr = 0.70975 ± 0.00139 (2σ,
n = 22), δ
13C
carbonate(V-PDB) = −14.8‰ ± 0.8‰ (1
σ,
n = 12), and δ
18O
carbonate(V-PDB) = −7.2‰ ± 1.0‰ (1
σ,
n = 12). Archaeological human bone samples exhibit mean δ
13C
collagen(V-PDB) = −20.8‰ ± 0.5‰ (1
σ,
n = 12) and mean δ
15N
collagen(AIR) = +10.0‰ ± 1.7‰ (1
σ,
n = 12). Comparing these data with archaeological faunal data from Dublin and published data from northern Europe, we argue that there are no clear immigrants from other parts of the North Atlantic, although there is one clear outlier in both origins and diet. Overall, the relative homogeneity in both paleomobility and paleodiet may support models of acculturation in Viking Dublin, rather than a high number of first-generation immigrants or continued migration from Scandinavia.
► We use biogeochemistry to investigate paleodiet and paleomobility in Viking Dublin. ► There are no Scandinavian immigrants in ninth through twelfth-century contexts. ► These data support acculturation rather than many first-generation immigrants.
The present study assessed for the first time the magnitude and dietary ecological source of total mercury (THg) exposure in a southern population of white-tailed eagles (Haliaeetus albicilla), an ...apex predator species shown valuable for environmental biomonitoring. This population depends on the Kopački rit Nature Park – the most important breeding site. We assessed THg exposure, using nestling body feathers collected between 2014–2019 (n = 72), and potential dietary ecological sources, proxied by prey remains and stable isotope analysis. Results show THg concentrations vary significantly over the years, though not showing any time trend. Prey remains analysis shows nests with aquatic prey remains to exhibit higher THg concentrations (median: 7.57 μg g−1 dw; min – max: 6.00–13.16 μg g−1 dw) compared to those with terrestrial remains (median: 3.94 μg g−1 dw; min – max: 0.28–12.04 μg g−1 dw) or evidencing a mixed diet (median: 7.43 μg g−1 dw; min – max: 3.38–12.04 μg g−1 dw). Nests with a predominant aquatic diet show elevated lower δ13C and higher δ15N values, indicating agreement between both dietary approaches. The model selection reveals a combination of year and δ15N best explain the variability in feather THg concentrations. Complementing these predictors with a dietary descriptor based on prey remains results in a poorer model fit and lowered explanatory power, similar to sexing the nestlings. The observed body feather THg concentrations (median: 6.99 μg g−1 dw; min − max: 0.27 − 17.16 μg g−1 dw) exceeded putative biogeochemical background levels (5.00 μg g−1 dw) in 71% of the nestlings, though, did not seem to exceed a threshold at which detrimental physiological effects are expected (40 μg g−1 dw). Continued monitoring is warranted as the studied population is likely exposed to a larger cocktail of contaminants while resident-protected bird areas.
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•First-time THg assessment in a southern population of White-tailed eagles.•THg, δ13C, and δ15N were investigated in nestling feathers from Nature Park Kopački rit.•Trophic position, proxied by δ15N, and sampling year best explain THg variation.•An aquatic diet is associated with elevated THg exposure.•>70% of nestlings exhibit THg concentration above the geochemical background.
The O2 content of the global ocean has been declining progressively over the past decades, mainly because of human activities and global warming. Despite this situation, the responses of macrobenthos ...under hypoxic conditions remain poorly understood. In this study, we conducted a long-term observation (2015–2022) to investigate the intricate impact of summer hypoxia on macrobenthic communities in a semi-enclosed bay of the North Yellow Sea. Comparative analyses revealed higher macrobenthos abundance (1956.8 ± 1507.5 ind./m2 vs. 871.8 ± 636.9 ind./m2) and biomass (8.2 ± 4.1 g/m2 vs. 5.6 ± 3.2 g/m2) at hypoxic sites compared to normoxic sites during hypoxic years. Notably, polychaete species demonstrated remarkable adaptability, dominating hypoxic sites, and shaping community structure. The decline in biodiversity underscored the vulnerability and diminished resilience of macrobenthic communities to hypoxic stressors. Stable isotope analysis provided valuable insights into food web structures. The average trophic level of macrobenthos measured 2.84 ± 0.70 at hypoxic sites, contrasting with the higher value of 3.14 ± 0.74 observed at normoxic sites, indicating the absence of predators at high trophic levels under hypoxic conditions. Moreover, trophic interactions were significantly altered, resulting in a simplified and more vulnerable macrobenthic trophic structure. The findings underscored the importance of comprehensive research to understand the complex responses of macrobenthic communities to hypoxia, thereby informing future conservation efforts in impacted ecosystems.
•The impact of summer hypoxia on macrobenthos was observed over the long term.•Hypoxic sites exhibited higher abundance and biomass but lower biodiversity.•Polychaetes dominated hypoxic sites and shaped the community structure.•Summer hypoxia shifts to a simplified and vulnerable benthic trophic structure.
The boreal forest is the single largest terrestrial store of carbon on Earth, and approximately 25% of these carbon stocks are in the forest floor. Climate change is expected to alter boreal ...vegetation, and aspen-dominated stands will replace conifers in Western Canada. We investigated how these vegetation shifts could affect the composition and function of soil microbial communities, using forest floor samples from the Ecosystem Management Emulating Natural Disturbance (EMEND) project in northwestern Alberta, Canada. Soil microbial communities were surveyed in rhizosphere and bulk forest floor of 17-year-old spruce clear-cuts where aspen was naturally regenerating, mature stands of aspen and spruce, and 17-year-old clear-cuts of aspen. Phospholipid fatty acid (PLFA) analysis was used to characterize microbial community composition and multiple substrate induced respiration (MSIR) to quantify microbial community functional capacity. Carbon source utilization by microorganisms was investigated through natural abundance isotope analysis of individual PLFAs. Rhizosphere samples had a significantly higher proportion of fungi and a higher gram-negative to gram-positive bacteria ratio compared to bulk soil. Fungi and gram-negative bacteria biomarkers in the rhizosphere showed 13C depletion compared to bulk forest floor, indicating that they had assimilated more newly-photosynthesized carbon than bulk forest floor microbes. Aspen trees exerted a greater influence over their rhizospheres than spruce trees in terms of microbial community composition and functional capacity, and aspen rhizospheres showed the highest basal respiration. In less than two decades, aspen regeneration in former spruce stands shifted the composition of microbial communities towards that of native aspen stands, with the rhizosphere microbiome responding more quickly than bulk forest floor. This study suggests that predicted vegetation shifts in the boreal have the potential to cause more immediate and profound changes in the rhizosphere, and emphasizes the need to include the rhizosphere in future studies.
•Clear differences existed between rhizosphere and bulk soil microbial communities.•Natural abundance 13C PLFA patterns differed between rhizosphere and bulk soil.•Vegetation shift caused changes in microbial communities in less than two decades.•Rhizosphere microbes responded more readily to the vegetation shift.
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