Radiocarbon Analysis Research Articles

RADIOCARBON STEP-COMBUSTION OXIDATION METHOD AND FTIR ANALYSIS OF TRONDHEIM CaCO3 PRECIPITATES OF ATMOSPHERIC CO2 SAMPLES: FURTHER INVESTIGATIONS AND INSIGHTS

ABSTRACT Eight atmospheric carbon dioxide samples (as calcium carbonate—CaCO3—precipitates) from Lindesnes site (58ºN, 7ºE), belonging to 1963 and 1980 (four samples from each year) and stored at the National Laboratory for Age Determination (NTNU), have been reevaluated through radiocarbon (14C) analysis. Previous 14C results indicated the presence of a contaminant, which was not removed through different chemical cleansing procedures (e.g., hydrochloric acid—HCl and/or hydrogen peroxide—H2O2). Here, we present a follow up investigation using 14C step-combustion and Fourier-transform infrared spectroscopy (FTIR) analysis. Results from 14C data indicate unsuccessful removal of the contaminant, while further FTIR analysis displayed the presence of moisture. This finding alludes to the possibility that the contaminant is of ambient air-CO2 deeply embedded in CaCO3 powders (within clogged CaCO3 pores and/or bonded to the lattice). Samples were found exposed to air-CO2 and humidity. These conditions may have lasted for years, possibly even decades, leading to the 14C offsets detected here.

Was Gordineşti II-Stînca Goala abandoned due to cultural changes or environmental impacts? A case of the late Trypillia settlement in northern Moldova

This study aims to provide information on cultural and environmental factors influencing the development and decline of the Late Trypillia settlement at Gordineşti II–Stînca goală. The discussion is based on the results of archaeological excavations, non-invasive surveys (magnetometric and GPR), as well as radiocarbon, macroremains, palynological, archaeozoological, and isotopic analyses. All data suggests that Gordineşti II–Stînca goală consisted of at least 15 lightweight constructed dwellings. It was a small settlement existing c. 3300-2950 BC. Its inhabitants were oriented to cereal cultivation and livestock husbandry, using available areas with fertile soils. The livestock were well-fed. However, the location of the settlement on a highly exposed outcrop probably did not facilitate the use of the flowing water of the nearby Racovăţ River. The rock underlying the site would have made digging the wells a very tough task. Hence, the water access problem may be one of the factors that made life inconvenient at the Gordineşti II-Stînca goală settlement.

PREPARATION AND HANDLING OF METHANE FOR RADIOCARBON ANALYSIS AT COLOGNEAMS

PREPARATION AND HANDLING OF METHANE FOR RADIOCARBON ANALYSIS AT COLOGNEAMS

Death Year Estimation of Skeletal Remains by Radiocarbon Dating of Femur

The identification for skeletal remains is one of roles of forensic medicine. For this purpose, dating, i.e., estimating the birth year and death year is expected as useful, however has not yet been practically applied. A dating method using radiocarbon analysis was recently introduced and related studies have been reported. In this study, we tried to confirm the applicability of radiocarbon dating for the identification of skeletal remains and to develop formulas to estimate the death year. Thirty-four autopsy cases from the National Forensic Service, from December 2014 to July 2022, with known death year were selected for inclusion. For each case, two samples were taken: the spongy bone of the femur head, and the compact bone of the femur midshaft. For each sample, radiocarbon analysis was carried out and the corresponding femur year were calculated using the bomb peak curve. The differences between the femur year and the death year were determined and analyzed on the influence of variables. A formula for estimating the death year was developed and the applicability of the formula was determined. The results showed that the difference between death year and femur head year was 14.2 years on average. In male, the difference between death year and femur head year increased with age, however, it did not show any difference according to age in female. The estimation formula of death year was as follows: (In male) Death year=0.993×(Femur head year)+0.288×(Age)+15.061, (In female) Death year=0.769×(Femur head year)-0.218×(Age)+489.676. The formula for male had relatively high explanatory power (adjusted R<sup>2</sup>=0.710), however, the formula for female had low explanatory power (adjusted R<sup>2</sup>=0.588). This study is meaningful because it is the largest single study of its kind, to date, and uses specific and identical skeleton (femur head/femur midshaft) to increase the accuracy of the death year estimation. We expect that the results of this study will be supplemented through additional research in the future.

Salt wedges and trapped brines of low-latitude endoreic saline lakes as potential modulators of GHG emission

Large salt lakes are long-term witnesses to climatic conditions and land use in their basins. The majority are experiencing a drastic drop in water levels due to climate change and human impact. Endoreic Lake Urmia (NW Iran), the sixth largest salt lake worldwide, is a striking example of this decline. Quantification of the relative contributions of natural variability and human impact on the lake's water supply is therefore essential. Here we present isotopic and radiocarbon analyses of surface and groundwater from the Shahr Chay River catchment, entering Lake Urmia on its western shore, and radiocarbon dating of a sedimentary core. Lake Urmia behaves like a large saltwater wedge almost entirely fed by the river and shallow groundwater. This leads to trapping of residual brines and formation of CH4 and secondary CO2 greenhouse gases, impacting sediment geochemical records and corresponding time scales for paleoenvironmental reconstructions. We conclude that (1) salt lakes functioning like a saline wedge, allowing organic matter oxidation, could contribute to increasing methane sources or reducing carbon sinks globally, and (2) endoreic basins worldwide need to be monitored before aridification-related salinization leads to the establishment of a saline wedge precluding any possibility of return to an equilibrium state.

Coupling of Dye Analysis and Compound Specific Radiocarbon (14C) Analysis (CSRA) in Heritage Sciences

Natural organic dyes and pigments have been used for millennia to bring colour into our daily lives. Being sourced from a variety of natural sources, they form an extremely varied and large class of compounds, all of which retain the atmospheric 14CO2 of their year of growth. As such these compounds represent ideal candidates for radiocarbon (14C) dating, allowing the identification of or providing information towards the period in which the coloured artefact was created. However, up to now no such analysis has ever been conducted solely on organic colourants within an object. The complex nature of the samples and the sample size limitations with respect to precious and rare art artefacts requires innovative inter- and multidisciplinary approaches. Here we discuss preliminary results in the development of a compound-specific radiocarbon analysis (CSRA) methodology for the analysis of anthraquinone derived red dyes extracted from dyed wool yarns. The aim of this research project is to introduce new routes to date cultural heritage objects, in particular to overcome their intrinsic complexity through the development of CSRA strategies.

The Zacatín rock shelter (Granada, Spain): New data on the Mesolithic-Neolithic transition in the south-eastern Iberian coast

This study presents a holistic analysis of the occupation sequence at the rock shelter of Zacatín (Gualchos-Castell de Ferro, Granada, Spain), a site in the cliffs along Andalusia's Mediterranean coastline. Despite being disturbed by cave-ins and erosion, it offers valuable information on the transition between the Mesolithic hunter-gatherers and the first Neolithic farming communities in southern Iberia. The study adopted an approach combining stratigraphical and radiocarbon analyses with typological, archaeozoological and archaeobotanical classifications. The stratigraphical sequence comprises four main phases. The uppermost level (Phase 4) yielded a combination of modern and displaced prehistoric elements. Intermediate Phases 3 and 2 correspond to Early Neolithic layers ranging between the mid-6th to the beginning of the 5th millennium cal BC. The Neolithic finds consist of incised and impressed potsherds, stone tools, ornaments (perforated shells and discoidal beads) as well as domestic animals (caprines) and plant (cereals) species. Although the older Mesolithic horizon (Phase 1) yielded few characteristic artifacts, radiocarbon datings place it in the 7th millennium cal BC. In any case, an original aspect of the site is the key role played by marine resources throughout both its Mesolithic and Neolithic phases.

Carbon dynamics during long-term starving poplar trees-the importance of older carbohydrates and a shift to lipids during survival.

Carbon (C) assimilation can be severely impaired during periods of environmental stress like drought or defoliation, making trees heavily dependent on the use of C reserve pools for survival; yet, dynamics of reserve use during periods of reduced C supply are still poorly understood. We used stem girdling in mature poplar trees (Populus tremula L. hybrids), a lipid-storing species, to permanently interrupt phloem C transport and induced C shortage in the isolated stem section below the girdle and monitored metabolic activity during three campaigns in the growing seasons of 2018, 2019, and 2021. We measured respiratory fluxes (CO2 and O2), NSC concentration, the respiratory substrate (based on isotopic analysis and CO2/O2 ratio) and the age of the respiratory substrate (based on radiocarbon analysis). Our study shows that poplar trees can survive long periods of reduced C supply from the canopy by switching in metabolism from recent carbohydrates to older storage pools with a potential mixture of respiratory substrates, including lipids. This mechanism of stress resilience can explain why tree decline may take many years until death occurs.

Multi-molecular 14C evidence for mineral control on terrestrial carbon storage andexport.

Compound- and compound class-specific radiocarbon analysis of source-diagnostic 'biomarker' molecules has emerged as a powerful tool to gain insights into terrestrial carbon cycling. While most studies thus far have focused on higher plant biomarkers (i.e. plant leaf-wax n-alkanoic acids and n-alkanes, lignin-derived phenols), tracing paedogenic carbon is crucial given the pivotal role of soils in modulating ecosystem carbon turnover and organic carbon (OC) export. Here, we determine the radiocarbon (14C) ages of glycerol dialkyl glycerol tetraethers (GDGTs) in riverine sediments and compare them to those of higher plant biomarkers as well as markers of pyrogenic (fire-derived) carbon (benzene polycarboxylic acids, BPCAs) to assess their potential as tracers of soil turnover and export. GDGT Δ14C follows similar relationships with basin properties as vegetation-derived lignin phenols and leaf-wax n-alkanoic acids, suggesting that the radiocarbon ages of these compounds are significantly impacted by intermittent soil storage. Systematic radiocarbon age offsets are observable between the studied biomarkers, which are likely caused by different mobilization pathways and/or stabilization by mineral association. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.

On Roth’s “human fossil” from Baradero, Buenos Aires Province, Argentina: morphological and genetic analysis

The “human fossil” from Baradero, Buenos Aires Province, Argentina, is a collection of skeleton parts first recovered by the paleontologist Santiago Roth and further studied by the anthropologist Rudolf Martin. By the end of the nineteenth century and beginning of the twentieth century it was considered one of the oldest human skeletons from South America's southern cone. Here, we present the results of an interdisciplinary approach to study and contextualize the ancient individual remains. We discuss the context of the finding by first compiling the available evidence associated with the historical information and any previous scientific publications on this individual. Then, we conducted an osteobiographical assessment, by which we evaluated the sex, age, and overall preservation of the skeleton based on morphological features. To obtain a 3D virtual reconstruction of the skull, we performed high resolution CT-scans on selected skull fragments and the mandible. This was followed by the extraction of bone tissue and tooth samples for radiocarbon and genetic analyses, which brought only limited results due to poor preservation and possible contamination. We estimate that the individual from Baradero is a middle-aged adult male. We conclude that the revision of foundational collections with current methodological tools brings new insights and clarifies long held assumptions on the significance of samples that were recovered when archaeology was not yet professionalized.

A NEW RAMPED OXIDATION-14C ANALYSIS FACILITY AT THE NEIF RADIOCARBON LABORATORY, EAST KILBRIDE, UK

ABSTRACTSample materials such as sediments and soils contain complex mixtures of different carbon-containing compounds. These bulk samples can be split into individual fractions, based on the temperature of thermal decomposition of their components. When coupled with radiocarbon (14C) measurement of the isolated fractions, this approach offers the advantage of directly investigating the residence time, turnover time, source, or age of the different components within a mixed sample, providing important insights to better understand the cycling of carbon in the environment. Several laboratories have previously reported different approaches to separate radiocarbon samples based on temperature in what is a growing area of interest within the research community. Here, we report the design and operation of a new ramped oxidation facility for separation of sample carbon on the basis of thermal resistance at the NEIF Radiocarbon Laboratory in East Kilbride, UK. Our new instrumentation shares some characteristics with the previously-reported systems applying ramped oxidation and/or ramped pyrolysis for radiocarbon measurement, but also has several differences which we describe and discuss. We also present the results of a thorough program of testing of the new system, which demonstrates both the reproducibility of the thermograms generated during sample combustion, and the reliability of the radiocarbon measurements obtained on individual sample fractions. This is achieved through quantification of the radiocarbon background and analysis of multiple standards of known 14C content during standard operation of the instrumentation.

A New Neolithic Site in the Nothern Caspian Region

Tuskuduk site’s materials from the North Caspian Sea region are published in an article. A goal of this work is characteristics of material culture’s remains, which were found as a result of excavation of 2022 year. The tasks of research include: description of the site, ceramics and stone inventory, their cultural attribution and determination of the place within the Neolithic of this region. During the research of the site, spatial, typological, statistical, archeozoological and radiocarbon methods were used. The nature of the cultural layer distribution was determined on the results of spatial analysis. The typological analysis made it possible to identify the features typical in ceramics and stone artifacts, to establish their characteristics in comparison with other complexes within the area of the interest. The archeozoological method contributed to the determination of the species composition of animals. Radiocarbon analysis specified the absolute age of the site. Based on the analysis of materials from the Taskuduk site, the presence of a preserved cultural layer was established. Ceramic and stone inventory belong to the Tenteksor cultural type of the Late Neolithic period. The specificity of the design of the upper parts of the vessels is revealed. Polished and drilled items were identified among the stone tools. Animal bones belong to wild species. The complex dates to 6700–6500 BP on radiocarbon determinations.

Investigation of the burial mounds of early nomads of the Irtysh river region of Semey

The article introduces materials of monuments studied in the Semeytau and Kokentau mountain ranges. During the period 2014–2018, the research team has unearthed 13 burial mounds, distributed across six burial grounds and groups of burial mounds. The accompanying artifacts comprise iron rods (pins?) and the tail vertebrae of a ram. In three cases (Karatobe burial ground, mounds no. 2 and 3; Karasu-Ushtobe burial ground, mound 1), necklaces crafted from semiprecious stones have been discovered. Armament items are represented by a set of bone and one bronze arrowheads. In general, the ground and inside burial mounds find analogies in the materials of the Kulazhorga type (3rd century BC – 1st century AD) within the Upper Irtysh region, as well as in burial mounds from the early stage (3rd–2nd centuries BC) of the Wusun archaeological culture in the Ile River valley. It is worth noting the proximity of the design features of the burial structures and the subject complex of most of the described mounds with the monuments of Saryarka, first of all, the greatest parallels can be traced among the materials of the monuments of the Karamola type. According to the results of radiocarbon analysis, the objects studied date back to the 5th–3rd centuries BC.

As above, so below: Deposition, modification, and reutilization of human remains at Marmoles cave (Cueva de los Marmoles: Southern Spain, 4000-1000 cal. BCE).

The deposition and manipulation of human remains in natural caves are well known for the Neolithic of Southern Iberia. The cultural meaning of these practices is however still largely unclear. Cueva de los Marmoles (CM, Priego-Córdoba) is one of the most important cave contexts from Southern Spain, which returned a large number of commingled skeletal remains suggesting its funerary use from the Neolithic to the Late Bronze Age. Here we discuss CM from a chronological and cultural perspective based on new radiocarbon, anthropological, and taphonomic analyses. These include the estimation of the minimum number of individuals, the exploration of fragmentation patterns characterizing different skeletal regions, and the macroscopic and microscopic analysis of modifications to the remains of possible anthropic origin. Radiocarbon data point to a funerary use of CM between the 5th -2nd millennium cal. BCE. MNI estimates reveal the presence of at least 12 individuals (seven adults and five nonadults). The low representation of elements from hands and feet suggests that individuals were placed in the cave while partially decomposed. Anthropic traces on the remains (e.g. fresh fractures, marrow canal modifications, and scraping marks) hint at their intentional fragmentation, cleaning from residual soft tissues, and in some cases reutilization. These practices are well-exemplified by the recovery of one "skull cup" and of two long bones used as tools. These data align with those from other cave contexts from the same geographic region, suggesting the presence, especially during the Neolithic period, of shared ideologies centered on the human body.

Large-scale mining and smelting of specularite ores in the Altai mountains during the 1st millennium AD

According to past historical documents and archaeological evidence, the Altai, rich in iron ore deposits, was a major iron production region in Eurasia during the 1st millennium AD. The present article focuses on the investigation of the large specularite (specular hematite) deposit Rudny Log in the Southeastern Altai (Russian part), long time regarded as a potential mine for the 1st millennium AD iron smelters. To test this hypothesis, we use complex approaches combining: 1) spatial analyses and field recording of traces of workings found at the mine; 2) radiocarbon dating; 3) microstructural (by OM and SEM); 4) geochemical (by XRF and ICP-MS) and 5) multivariate statistical investigation of iron ore and slag samples found at the mine and seven major ancient iron smelting sites in the Southeastern Altai.The results of spatial analysis and fieldwork carried out at the mine reveal the presence of c. 350 pit workings from ancient exploitation, which can be estimated as c. 2500 tons of extracted ore. The radiocarbon analyses indicate the 1st-2nd c. AD timeframe to the start of the exploitation of the mine and the earliest iron smelting in the Southeastern Altai, which is likely linked to the Xiongnu expansion. The materials and statistical analyses allow us to preliminary identify Rudny Log, or, alternatively, another major deposit in the region, as the main source for five major iron production sites operated during the 1st millennium AD. Apart from that, the analyses suggest the exploitation of two currently unknown ore sources at three of the smelting sites. The significant scatter and remoteness of metallurgical centers from the mine can be associated with the nomadic subsistence of smelters who integrated seasonal metallurgical production with the search for new pastures and fuel resources.

THE PROGRESS OF 14C-AMS ANALYSIS FOR ULTRA-SMALL SAMPLES AT XI’AN AMS CENTER

ABSTRACT As there exists a growing demand for chronological research and tracer applications using radiocarbon (14C) analyses of samples smaller than 100 μg C, a compact micro-specific hydrogen graphitization method has been developed at the Xi’an Accelerator Mass Spectrometry (AMS) Center. This article describes the performance of the system and the mass of carbon background produced during ultra-small sample preparation. Furthermore, we discuss the results of contamination corrections and perform 14C analyses on small samples with known age or reference values. The results reveal that our 14C analysis of ultra-small samples of 10–100 μg C can obtain accurate and reliable results, and the micro-scale 14C-AMS analysis technique meets our research objectives for dating and tracer applications.

Distinct Modes of Aged Soil Carbon Export in a Large Tropical Lake Basin Identified Using Bulk and Compound‐Specific Radiocarbon Analyses of Fluvial and Lacustrine Sediment

AbstractThe 14C content of sedimentary organic matter (OM) and specific organic molecules provide valuable information on the source and age of OM stored in sediments, but these data are limited for tropical fluvial and lake sediments. We analyzed 14C in bulk OM, palmitic acid (C16), and long‐chain n‐alkanoic acids (C24, C26, and C28), within fluvial and lake sediments in the catchment of Lake Izabal, a large tectonic lake basin in Guatemala. We combined these measurements with bulk and compound‐specific δ13C measurements, as well as sediment organic carbon to nitrogen (OC:N) ratios, to understand the source and age of sedimentary OM in different regions of the lake catchment. Most fatty acid and bulk OM samples were characterized by pre‐modern carbon, indicating important input of aged carbon with residence times of hundreds to thousands of years into sediments. We identified two mechanisms leading to aged carbon export to sediments. In the high‐relief and deforested Polochic catchment, older OM and fatty acids are associated with low % total organic carbon (TOC) and low OC:N, indicating aged OM associated with eroded mineral soil. In the smaller, low‐relief, and largely forested Oscuro catchment, old OM and fatty acids are associated with high %TOC and high OC:N ratios, indicating export of undegraded aged plant biomass from swamp peat. The age of bulk OM and fatty acids in Lake Izabal sediments is similar to the ages observed in fluvial sediments, implying that fluvial input of aged soil carbon makes an important contribution to lake sediment carbon reservoirs in this large tropical lake.

Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years

AbstractThe radiocarbon analysis of uranium‐thorium‐dated cold‐water corals (CWCs) provides an excellent opportunity for qualitative reconstruction of past ocean circulation and water mass aging. While mid‐depth water mass aging has been studied in the Atlantic Ocean, the evolution of the thermocline is still largely unknown. Here we present a combined 14C and 230Th/U age record obtained from thermocline dwelling CWCs at various sites in the eastern Atlantic Ocean, with intermittently centennial resolution over the last 32 ka. Shallow dwelling CWCs off Angola, located in the South Atlantic, infer a link between the mid‐depth equatorial Atlantic and Southern Ocean. They confirm a 14C drawdown during the Last Glacial Maximum (LGM) and advocate for a consistent Southern Hemisphere radiocarbon aging of upper thermocline waters, as well as strong depth gradients and high variability. Direct comparison with 14C simulations carried out with an Ocean General Circulation Model yield good agreement for Angola. In contrast, the North Atlantic thermocline shows well‐ventilated water with strong variations near the position of today's Azores Front (AF), neither of which are captured by the model. During the Bølling‐Allerød, we confirm the important role of the AF in separating North and South Atlantic thermocline waters and provide further evidence of a 500 year long deep convection interruption within the Younger Dryas (YD). We conclude that the North and South Atlantic thermocline waters were separately acting carbon reservoirs during the LGM and subsequent deglaciation until the modern circulation was established during the YD.

Новая неолитическая стоянка Приозерная в Нижнем Поволжье

Introduction. The Lower Volga region attracts the attention of specialists because the ancient cultures of this region had a great influence on neighboring regions. This also applies to the Neolithic era, when the inhabitants of this territory had the oldest ceramic production and cattle breeding. A number of questions remain open, as new sources are required. One of them is the site of Priozernaya in the southern part of the Lower Volga region. Methods and materials. Planographic and stratigraphic methods are used to identify the nature of the monument. According to the results of the technical and technological analysis, the ceramics are made of silt. The results of the typological method reveal flat-bottomed vessels ornamented with receding incisions in a geometric style. Stone tools are represented by scrapers, spikes, and knives. Spears and spearheads are made of bones. According to the results of archeozoological analysis, tur, kulan, saiga, tarpan, etc. are represented. According to the results of radiocarbon analysis, dates are obtained. It is 6700–6600 years BP for animal bones and ceramics. Results. The results of the spatial analysis reveal the presence of remnants of dwelling structures. The manufacturing technology and typology of ceramics and stone tools allow us to attribute the monument to the Tentexor type of the late stage of the Neolithic of the Northern Caspian. The results of the faunal analysis confirm the presence of only wild animal species. The hypothesis about the appearance of a producing economy in this region at the late stage of the Neolithic has not been confirmed. Only the dog belongs to the domesticated animals. According to the results of radiocarbon analysis, the site functioned in the second quarter of the 6th millennium BC. The monument is a short-lived hunting camp. The pattern application techniques and the nature of ornamental compositions allow us to detect similarities with the ceramics of the Caspian culture. This suggests assuming the participation of the local Neolithic population in the genesis of the bearers of the Eneolithic tradition. Authors contribution. T.Yu. Grechkina wrote sections about planographic and stratigraphic methods. A.A. Vybornov described ceramic and stone tools. The results are written together.

Distinct variations and mechanisms for terrestrial OC 14C-ages in the Eastern China marginal sea sediments since the last deglaciation

Marginal seas serve as the depocenter and reactor for terrestrial organic carbon (OC) transported by fluvial systems, however, mechanisms controlling the preservations and radiocarbon ages of down-core sedimentary terrestrial OC still remain poorly understood. Here, we employ radiocarbon analyses of both bulk OC and compound-specific terrestrial biomarker (long chain fatty acids) on sediment cores collected from the Eastern China marginal seas with depositional ages spanning the last 14 kyr. In the southern Yellow Sea (core C04), we find persistent high burial efficiency (94 ± 27% on average) of aged terrestrial OC with apparent initial radiocarbon ages (AIRs, i.e., radiocarbon age corrected for natural decay since deposition) of 1521–6115 yr, which showed an increasing trend from the marine transgression stage to the mid-late Holocene. This trend reflected changes of terrestrial OC age transported by the Huanghe (Yellow River), which in turn was caused by deeper soil erosion of older OC from the Chinese Loess Plateau when rainfall was higher during the mid-late Holocene. In contrast, terrestrial OC AIRs in the East China Sea (core F10B) were significantly older than those in the southern Yellow Sea, with an opposite trend of higher values during marine transgression stage compared with the mid-late Holocene. This spatial difference may arise from significant hydrodynamic process aging in the East China Sea, which further elevated terrestrial OC ages during lateral transports. Our results revealed contrasting scenarios of terrestrial OC ages and preservations in the southern Yellow Sea and the East China Sea, underscoring the important roles of hydroclimate and regional hydrodynamic processes in regulating the burial of terrestrial OC in marginal seas.