Radiocarbon Analysis Research Articles

Palaeopathological Study of the Mompaderno Cranium (Croatian Istria) Reveals Interpersonal Violence during Early Bronze Age

AbstractThe Mompaderno cranium was found in 1883 at Baderna/Mompaderno in Croatian Istria. It was suspected to date from the Mesolithic or Neolithic period, but radiocarbon analyses, performed by accelerator mass spectrometry (AMS) on collagen extracted from two teeth, have provided an age range of 2,202–1928 cal. BC, which corresponds to the Early Bronze Age in the investigated region. Macroscopic observations and X‐ray micro‐tomography (micro‐CT) of the cranium have shown antemortem sharp force trauma on the frontal bones, probably caused by a bronze axe, and a related osteomyelitis likely caused by an infection of the wound. The study has also revealed a previous depressed fracture and an osteolytic area interpreted as intradiploic meningioma. Results provide rare and earliest evidence of interpersonal violence in the northern Adriatic region.

Gothic-Arch Calcite from Speleothems of the Bohemian Karst (Czech Republic): Its Occurrence, Microscopic Ultrastructure and Possible Mechanism of Growth

Gothic arch calcite, a specific crystallographic variety of calcite known from some hot springs and tufa streams, has been newly recognized in the Koněprusy Caves. The gothic-arch calcite occurs on the exteriors of exotic coralloid speleothems where it coexists with scalenohedral (dogtooth) spar crystals. The crystals exhibit microscopic ultrastructural features including deeply eroded topography, etch pits, and spiky and ribbon calcite crystallites, pointing to its extensive natural etching. Many gothic-arch calcites originated as late-stage, secondary overgrowths on older, etched dogtooth calcite crystals. Its characteristic outward curvature resulted from the recrystallization of etching-liberated fine carbonate grains and newly formed needle-fiber calcite laths, which were accumulated and bound on the faces and at the bases of corroded crystals. These intimately coexisting destructive and constructive processes of carbonate crystal corrosion and growth were probably mediated by bacteria, fungi, or other microorganisms. Fluid inclusions embedded in calcite crystals point to a vadose setting and temperatures below ~50 °C. This, combined with the wider geological context, indicates that the gothic arch calcite crystals originated only during the late Pleistocene to Holocene epochs, when the cave, initially eroded by hypogene fluids in the deeper subsurface, was uplifted to the subaerial setting and exposed to the meteoric waters seeping from the topographic surface. The radiocarbon analysis shows that gothic-arch calcite crystals are generally older than ~55,000 years, but the surface layers of some crystals still reveal a weak 14C activity, suggesting that microbiologically mediated alterations of the speleothems may have been occurring locally until now.

The Multiscale Monitoring of Peatland Ecosystem Carbon Cycling in the Middle Taiga Zone of Western Siberia: The Mukhrino Bog Case Study

The peatlands of the West Siberian Lowlands, comprising the largest pristine peatland area of the world, have not previously been covered by continuous measurement and monitoring programs. The response of peatlands to climate change occurs over several decades. This paper summarizes the results of peatland carbon balance studies collected over ten years at the Mukhrino field station (Mukhrino FS, MFS) operating in the Middle Taiga Zone of Western Siberia. A multiscale approach was applied for the investigations of peatland carbon cycling. Carbon dioxide fluxes at the local scale studied using the chamber method showed net accumulation with rates from 110, to 57.8 gC m−2 at the Sphagnum hollow site. Net CO2 fluxes at the pine-dwarf shrubs-Sphagnum ridge varied from negative (−32.1 gC m−2 in 2019) to positive (13.4 gC m−2 in 2017). The cumulative May-August net ecosystem exchange (NEE) from eddy-covariance (EC) measurements at the ecosystem scale was −202 gC m−2 in 2015, due to the impact of photosynthesis of pine trees which was not registered by the chamber method. The net annual accumulation of carbon in the live part of mosses was estimated at 24–190 gC m−2 depending on the Sphagnum moss species. Long-term carbon accumulation rates obtained by radiocarbon analysis ranged from 28.5 to 57.2 gC m−2 yr−1, with local extremes of up to 176.2 gC m−2 yr−1. The obtained estimates of various carbon fluxes using EC and chamber methods, the accounting for Sphagnum growth and decomposition, and long-term peat accumulation provided information about the functioning of the peatland ecosystems at different spatial and temporal scales. Multiscale carbon flux monitoring reveals useful new information for forecasting the response of northern peatland carbon cycles to climatic changes.

Seaside Recreation Ground: A Multi-Proxy Palaeoenvironmental Investigation on the Coastal Edge of the Willingdon Levels, Eastbourne, East Sussex, UK

ABSTRACT The Willingdon Levels hold some of the best-preserved prehistoric archaeological and palaeoenvironmental remains in south-east England. This study aims to characterise the previously unexplored coastal limits of the Willingdon Peat and compare the chronology with known sites. The degree of anthropogenic influence on vegetation cover in prehistory is of significant interest to archaeologists, and this paper aims to strengthen the case for human-induced landscape alteration surrounding the Willingdon Levels in the Bronze Age. Lithological, palynological, entomological, ostracod, foraminifera, diatom and radiocarbon analyses were applied to a sequence of deposits at Seaside Recreation Ground. This paper palaeoenvironmentally reconstructs the coastal edge of the Willingdon wetland and proposes a timing for the main period of peat initiation that occurred across the Levels. A decline in woodland taxa and the presence of cereal pollen allude to human presence in the landscape. The results have contributed to the Willingdon Levels modelling project.

New evidence for supplementary crop production, foddering and fuel use by Bronze Age transhumant pastoralists in the Tianshan Mountains

The nature of economies and the movement of agricultural crops across Eurasia in the Bronze Age have been the subject of significant research interest in recent years. This study presents and discusses new results of flotation, radiocarbon and carbon stable isotope analyses from the seed assemblage at the Adunqiaolu site (northwestern Xinjiang), in combination with archaeological evidence. Archaeobotanical evidence, including carbonized foxtail millet, broomcorn millet, and naked barley, documents the diversity of local cereal consumption during the mid-second millennium BC. Our results suggest that crops were not grown locally, however, but in the lower Boertala Valley, supporting the argument that Adunqiaolu was a winter camp. These new sets of data constitute an important contribution to the discussion on cereal dispersal across the Tianshan Mountains in the Bronze Age.

The Reservoir Age Effect Varies With the Mobilization of Pre-Aged Organic Carbon in a High-Altitude Central Asian Catchment

Lake sediments provide excellent archives to study past environmental and hydrological changes at high temporal resolution. However, their utility is often restricted by chronological uncertainties due to the “reservoir age effect” (RAE), a phenomenon that results in anomalously old radiocarbon ages of total organic carbon (TOC) samples that is mainly attributed to the contribution of pre-aged carbon from aquatic organisms. Although the RAE is a well-known problem especially in high altitude lakes, detailed studies analyzing the temporal variations in the contribution of terrestrial and aquatic organic carbon (OC) on the RAE are scarce. This is partially due to the complexity of isolating individual compounds for subsequent compound-specific radiocarbon analysis (CSRA). We developed a rapid method for isolating individual short-chain (C16and C18) and long-chain (>C24) saturated fatty acid methyl esters (FAMEs) by using high-pressure liquid chromatography (HPLC). Our method introduces only minor contaminations (0.50 ± 0.22 µg dead carbon on average) and requires only few injections (≤10), therefore offering clear advantages over traditional preparative gas chromatography (prep-GC). Here we show that radiocarbon values (Δ14C) of long-chain FAs, which originate from terrestrial higher plant waxes, reflect carbon from a substantially pre-aged OC reservoir, whereas the Δ14C of short-chain FAs that originate from aquatic sources were generally less pre-aged.14C ages obtained from the long-chain FAs are in closer agreement with14C ages of the corresponding bulk TOC fraction, indicating a high control of pre-aged terrestrial OC input from the catchment on TOC-derived14C ages. Variations in the age offset between terrestrial and aquatic biomarkers are related to changes in bulk sediment log(Ti/K) that reflect variations in detrital input from the catchment. Our results indicate that the chronological offset between terrestrial and aquatic OC in this high-altitude catchment is mainly driven by temporal variations in the mobilization of pre-aged OC from the catchment. In conclusion, to obtain accurate and process-specific lake sediment chronologies, attention must be given to the temporal dynamics of the RAE. Variations in the apparent ages of aquatic and terrestrial contributions to the sediment and their mass balance can substantially alter the reservoir age effect.

Solomon, Scripture, and Science: The Rise of the Judahite State in the 10th Century BCE

This paper compares evidence from stratified sites that are well dated by radiocarbon analyses, ceramic typology, and a critical reading of the pertinent texts of the Hebrew Bible. The results show that by the 10th century BCE in Judah we have a polity that represents a centralized state or kingdom. It was likely ruled by Solomon, even if the “larger-than-life” portrait of the Bible is exaggerated.

TIME-INTEGRATED COLLECTION OF CO2FOR14C ANALYSIS FROM SOILS

ABSTRACTWe developed a passive sampler for time-integrated collection and radiocarbon (14C) analysis of soil respiration, a major flux in the global C cycle. It consists of a permanent access well that controls the CO2uptake rate and an exchangeable molecular sieve CO2trap. We tested how access well dimensions and environmental conditions affect collected CO2, and optimized cleaning procedures to minimize14CO2memory. We also deployed two generations of the sampler in Arctic tundra for up to two years, collecting CO2over periods of 3 days–2 months, while monitoring soil temperature, volumetric water content, and CO2concentration. The sampler collects CO2at a rate proportional to the length of a silicone tubing inlet (7–26 µg CO2-C day-1·m Si-1). With constant sampler dimensions in the field, CO2recovery is best explained by soil temperature. We retrieved 0.1–5.3 mg C from the 1st and 0.6–13 mg C from the 2nd generation samplers, equivalent to uptake rates of 2–215 (n=17) and 10–247 µg CO2-C day-1(n=20), respectively. The method blank is 8 ± 6 µg C (mean ± sd,n=8), with a radiocarbon content (fraction modern) ranging from 0.5875–0.6013 (n=2). The sampler enables more continuous investigations of soil C emission sources and is suitable for Arctic environments.

Late Glacial and postglacial seismicity in the Northeastern Fennoscandian Shield: tectonic position and age of paleo-earthquakes near Murmansk

Earthquake-induced deformations located near Murmansk City were investigated for information on the age, tectonic position and spatial occurrence of paleo-earthquakes. The main earthquake-generating zone is identified to be the system of strike slip faults and reverse-oblique faults trending NNW along the Kola River valley. We used radiocarbon analysis and paleogeographic reconstructions and revealed three episodes of increased seismic activity: from 9500 to 10500 cal BP, from 892 to 1182 cal BP, and from 200 to 300 cal BP. Based on the peak ground velocity estimation method we suggest that an earthquakes with a maximum moment magnitude up to Mw ≈ 6.0–6.5 may have taken place in the studied area. The recorded location of seismogenic deformation near faults indicates area of strong Late Glacial and Holocene earthquakes occurring in the northern Kola Peninsula; this is also consistent with observations concerning the historical events of 1772 and 1873, which took place near the area.Combined with previous data on palaeoseismicity in Kola region, our studies indicate a longer lasting and more complex spatial and temporal history of postglacial seismicity in the Northeastern Fennoscandian Shield area. In contrast to the generally accepted opinion, strong seismic events occurred not only during the deglaciation period or immediately after it, but continued until the late Holocene and the last centuries. Glacial isostasy as a factor giving rise to stresses has become minimal by the present time, while the tectonic factor continues to be felt.

Veitstu hvé blóta skal? The Old Norse blót in the Light of Osteological Remains from Frösö Church, Jämtland, Sweden

The osteological remains from Frösö Church, Jämtland, have been re-analysed in order to understand the Viking Age rituals at the site and to study the blót, the Old Norse sacrifice and feast. Radiocarbon analyses of ani- mal and human bones date the rituals to the late Viking Age. A taphonomic study shows that especially brown bear and pig were of importance in the rituals. Butcher- ing marks reveal the processing of the carcasses as well as feasting. Further, bones and not whole carcasses seem to have been deposited on the ground. Human remains have been treated differently from the animal bones and may represent disturbed burials rather than sacrifices. Seasonal analysis indicates that the rituals took place in late autumn, early spring, and possibly around the summer solstice. The results of the osteological analy- ses are also discussed in relation to the written sources about the Old Norse blót.

Advances in increment coring system for large tropical trees with high wood densities

Incremental coring of trees is the key method used in non-destructive dendrochronological sampling. Despite the advances in developing such methods, the sampling of large, high-density trees still poses a challenge in remote tropical forests. Manually operated incremental drills, while easy to transport across difficult terrain, limit sample size and can often get damaged in the sampling process, especially when trees have wood densities above 0.8 g/cm³. Here, we discuss the existing available alternatives and present an up-to-date incremental coring system composed of a borer coupled to a hand-held drilling machine and a support attached to the tree which can collect incremental cores of 1.5 mm in diameter and over 1.0 m in length. The support ensures stability for the drill throughout the sampling process. This system is relatively lightweight and portable, offering field flexibility and suitability for sampling in remote locations. It provides a core sample of an appropriate diameter and amount for carrying out ring-width measurements, stable isotope and radiocarbon analyses on some of the large, older trees which are now being found in the tropics. We expect that this methodology will broaden the possibilities in the now-blossoming sub-field of tropical dendrochronology.

FOSSIL FUEL ENVIRONMENTAL CONTAMINATION: A STRATEGY USING RADIOCARBON, N-ALKANES, AND ALGAE

ABSTRACTFossil fuels are of utmost importance to the world we live in today. However, their use can cause major impacts on the environment, especially on water resources. In this regard, algae have been intensively used as a strategy for remediation and monitoring of environmental pollution due to its efficient absorption of contaminants. In this work, samples of seaweed collected in Niterói/RJ—contaminated with kerosene and diesel—were analyzed by radiocarbon (14C) accelerator mass spectrometry (AMS) and by n-alkane quantification with gas chromatography to evaluate bioaccumulation in function of the dosage of contaminants. The biogenic content measured by radiocarbon analysis resulted in 95.6% for algae contaminated with 10 mL of kerosene and 67.6% for algae contaminated with 10 mL of diesel. The maximum intensity of n-C17 n-alkane in algae with 5 mL, 10 mL, and 15 mL of diesel was 768.2, 1878.1, and 5699.2 ng.g-1, respectively. While the maximum concentration of n-C27 in algae with 5 mL, 10 mL and 15 mL of kerosene was 3.3, 35.9, and 150.3 ng.g-1. We concluded that, for both contaminants, their incorporation into algae increases as the contamination dosage increases, making this methodology an effective technique for monitoring and remediation of urban aquatic ecosystems.

Evidence of the 1950 Great Assam Earthquake Surface Break Along the Mishmi Thrust at Namche Barwa Himalayan Syntaxis

AbstractPaleoseismological trenching at Kamlang Nagar along the Mishmi Thrust in the Eastern Himalayan Syntaxis, aided by radiocarbon analyses of charcoals yielding ages of 1111–914 B.C. to A.D. 1761–1968 infer primary evidences of co‐seismic surface faulting. Correlation with results of an earlier paleoseismological study indicates two successive surface rupturing earthquakes at ∼1800‐years interval, the most recent event very likely corresponding to the 1950 Assam earthquake (Mw 8.6). A dip‐slip displacement of 24.6 ± 4.6 m was estimated along a 25 ± 5°E dipping fault during the 1950 earthquake. Our study suggests dual surface faulting by the 1950 event along two orthogonal fault systems, that is, the Himalayan Frontal Thrust and the Mishmi Thrust. It thus emphasizes that, the seismicity pattern in the Mishmi Range where the locked zone of the Main Himalayan Thrust extends beyond the suture zone, is unlike that of the western and central Himalaya.

Efficient Sampling of Atmospheric Methane for Radiocarbon Analysis and Quantification of Fossil Methane.

Radiocarbon (14C) measurements offer a unique investigative tool to study methane emissions by identifying fossil-fuel methane in air. Fossil-fuel methane is devoid of 14C and, when emitted to the atmosphere, causes a strong decrease in the ratio of radiocarbon to total carbon in methane (Δ14CH4). By observing the changes in Δ14CH4, the fossil fraction of methane emissions can be quantified. Presently, there are very few published Δ14CH4 measurements, mainly because it is challenging to collect and process the large volumes of air needed for radiocarbon measurements. We present a new sampling system that collects enough methane carbon for high precision Δ14CH4 measurements without having to transport large volumes of air. The system catalytically combusts CH4 into CO2 and adsorbs the combustion-derived CO2 onto a molecular sieve trap, after first removing CO2, CO, and H2O. Tests using reference air show a Δ14CH4 measurement repeatability of 5.4‰, similar or better than the precision in the most recent reported measurements. We use the system to produce the first Δ14CH4 measurements in central London and show that day-to-day differences in Δ14CH4 in these samples can be attributed to fossil methane input. The new system could be deployed in a range of settings to investigate CH4 sources.

THE GATE OF THE MEDIEVAL SITE OF KOSKUDUK

The article considers the topographic location, chronology, economy and excavations of the medieval site of Koskuduk, located in the Shui Valley. Although the first information about this site entered scientific circulation in the late 1980-th, accurate and scale excavations were not carried out. The Shui archaeological detachment (head Y.Sh. Akymbek) of the Institute of Archaeology named after A.Kh. Margulan in 2018 in the eastern corner of the medieval site of Koskuduk was organized the test pit, shurf and in 2019 on the site of the North-Eastern gate excavates and receives valuable information about the periodization, fortification, the economy of medieval city. The authors of the article draw the special attention to the etymology of the names of the gates in general, medieval gate structures in the Shui Valley, based on researched of other city gates. The radiocarbon analysis of charcoal from pit was carried out in 2018, and it was established that the site dates back to the XI-XII centuries (1043-1104 (41.1%) calAD; 1117-1211(54.3%) calAD). The ceramics complex, discovered at the gate site, is dominated by tableware. The X-ray diffractometric analysis of one instance of kitchen and dining utensils was carried out in order to determine which minerals are contained in the clay of the detected ceramic products. As the result, although the minerals and other impurities in the clay composition of the dishes are generally the same, there are significant differences in percentages. There are number of whole buried skeletons of dogs and partially entire preserved skeletons of horses were found at the gate zone. In addition, archaeozoological analysis of other osteological materials identified in the excavations was carried out, as well as comparative studies of the external forms of pets (cattle and dogs).

PALEOPARASITOLOGICAL ANALYSES OF CAVE BEAR (URSUS KANIVETZ VERESHCHAGIN, 1973) COPROLITES FROM THE IGNATIEVSKAYA CAVE (SOUTHERN URAL)

The first paleoparasitological analysis of coprolites of a cave bear (Ursus kanivetz Vereshchagin, 1973) was performed. Material for research was obtained from different deeps at the excavation of Ignatievskaya Cave (Chelyabinsk Region, Southern Urals, Russia, 54°53’N 57°46’E). Fossil coprolites were find from the excavations N 1-2, situated et the 120 meters from the entry of cave. The depth of excavations was 1.9 m. Radiocarbon analysis show that the age of cave bear bones was more than 27500 years. Coprolites were analyzed by combine method and sedimentation. Slides were viewed under the Meiji microscope with Х100 and Х400 magnification and made a pictures by the Vision camera. Eggs were defined using scientific descriptions available in the national and foreign literature. As a result from the paleoparasitological analysis, the presence Nematodes eggs was detected. Eggs are belonged to Baylisascaris transfuga Rudolphi, 1819 – specific parasite of Ursidae. Obviously, that helminth infected different species of bears already at the Late Pleistocene period and had a wide spreading. This is the first finding of the nematode B. transfuga of Pleistocene age and the first finding of parasites in the cave bear coprolites.

Radiocarbon analysis of tree ring for a catastrophic collapse in the northern Yatsugatake volcanoes: Its implication for seismotectonics in southwest Japan

In the late ninth century, the northern Yatsugatake volcanoes in central Japan experienced a catastrophic collapse, simultaneously causing a debris-avalanche. Such failures have been related to the AD 887 Nin'na earthquake, which occurred along the Nankai Trough. However, supportive evidence of the hypothesis remains unavailable. The present study reports wiggle match radiocarbon (14C) dating of a buried tree excavated from a deep part of the debris deposit. The death year of the buried tree was dated as AD 838 ± 17. The date exactly matches an inference of the AD 887 earthquake obtained from historical documents and field records of archaeological ruins, considering that 14C ages of Japanese trees have a regional offset of ≈30 years greater than the IntCal dataset. Our result suggests that the AD 887 earthquake occurred along about 700 km extending from the western margin of the Nankai Trough to the central segment of the Itoigawa-Shizuoka Tectonic Line.

Old finds, new data: Early Bronze Age human remains from Vučedol, eastern Croatia

Vučedol is a site of major importance in the Carpathian Basin that provides valuable insight into daily life from the Early Neolithic to the Late Bronze Age. During the first archaeological excavations at the Vučedol–Streim Vineyard site in 1897, a total of 15 graves were excavated. Today eight skulls from this field campaign are curated at the Archaeological Museum in Zagreb. Combining modern methods with the study of archival materials, we present new results from archaeological, osteological, radiocarbon, and isotopic analyses of these individuals that demonstrate the dynamic cultural connections that existed during the Early Bronze Age in this region.

Application of the ECT9 protocol for radiocarbon-based source apportionment of carbonaceous aerosols

Abstract. Carbonaceous aerosol is mainly composed of organic carbon (OC) and elemental carbon (EC). Both OC and EC originate from a variety of emission sources. Radiocarbon (14C) analysis can be used to apportion bulk aerosol, OC, and EC into their sources. However, such analyses require the physical separation of OC and EC. Here, we apply of ECT9 protocol to physically isolate OC and EC for 14C analysis and evaluate its effectiveness. Several reference materials are selected, including two pure OC (fossil “adipic acid” and contemporary “sucrose”), two pure EC (fossil “regal black” and “C1150”), and three complex materials containing contemporary and/or fossil OC and EC (“rice char”, NIST urban dust standards “SRM1649a” and “SRM8785”, i.e., fine fraction of resuspended SRM1649a on filters). The pure materials were measured for their OC, EC, and total carbon (TC) mass fractions and corresponding carbon isotopes to evaluate the uncertainty of the procedure. The average accuracy of TC mass, determined via volumetric injection of a sucrose solution, was approximately 5 %. Ratios of EC/TC and OC/TC were highly reproducible, with analytical precisions better than 2 % for all reference materials, ranging in size from 20 to 100 µg C. Consensus values were reached for all pure reference materials for both δ13C and fraction modern (F14C), with an uncertainty of < 0.3 ‰ and approximately 5 %, respectively. The procedure introduced 1.3 ± 0.6 µg of extraneous carbon, an amount compatible to that of the Swiss_4S protocol. In addition, OC and EC were isolated from mixtures of pure contemporary OC (sucrose) with pure fossil EC (regal black) and fossil OC (adipic acid) with contemporary EC (rice char EC) to evaluate the effectiveness of OC and EC separation. Consensus F14C values were reached for all OC (∼ 5–30 µg) and EC (∼ 10–60 µg) fractions with an uncertainty of ∼ 5 % on average. We found that the ECT9 protocol efficiently isolates OC or EC from complex mixtures. Based on δ13C measurements, the average contribution of charred OC to EC is likely less than 3 % when the OC loading amount is less than 30 µg C. Charring was further assessed by evaluating thermograms of various materials, including aerosol samples collected in the Arctic and from tailpipes of gasoline or diesel engines. These data demonstrate that the ECT9 method effectively removes pyrolyzed OC. Thus, the ECT9 protocol, initially developed for concentration and stable isotope measurements of OC and EC, is suitable for 14C-based apportionment studies, including µg C-sized samples from arctic environments.

GENERATION OF TWO NEW RADIOCARBON STANDARDS FOR COMPOUND-SPECIFIC RADIOCARBON ANALYSES OF FATTY ACIDS FROM BOG BUTTER FINDS

ABSTRACTThe analysis of processing standards alongside samples for quality assurance in radiocarbon (14C) analyses is critical. Ideally, these standards should be similar both in nature and age to unknown samples. A new compound-specific approach was developed at the University of Bristol for dating pottery vessels using palmitic and stearic fatty acids extracted from within the clay matrix and isolated by preparative capillary gas chromatography. Obtaining suitable potsherds for use as processing standards in such analyses is not feasible, so we suggest that bog butter represents an ideal material for such purposes. We sampled ca. 450 g from two bog butter specimens and homogenized them by melting. We verified the homogeneity of both specimens by characterization of their lipid composition, δ13C values of individual lipids, and both bulk- and compound-specific radiocarbon analyses on 10 sub-samples of each bog butter specimen. The weighted means of all 14C measurements on the bog butter standards are 3777 ± 4 BP (IB33) and 338 ± 3 BP (IB38), thereby providing age-relevant standards for archaeological and historical fatty acids and ensuring the accuracy of radiocarbon determinations of lipids using a compound-specific approach. These new secondary standards will be subjected to an intercomparison exercise to provide robust consensus values.