Radiocarbon Analysis Research Articles

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.

Impact of fossil and non-fossil fuel sources on the molecular compositions of water-soluble humic-like substances in PM2.5 at a suburban site of Yangtze River Delta, China

Abstract. Atmospheric humic-like substances (HULIS) affect the global radiation balance due to their strong light absorption at the ultraviolet wavelength. The potential sources and molecular compositions of water-soluble HULIS at a suburban site in the Yangtze River Delta from 2017 to 2018 were discussed, based on the results of the radiocarbon (14C) analysis and combining the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) technique in this study. The 14C results showed that the averaged non-fossil-fuel source contributions to HULIS were 39 ± 8 % and 36 ± 6 % in summer and winter, respectively, indicating significant contributions from fossil fuel sources to HULIS. The Van Krevelen diagrams obtained from the FT-ICR-MS results showed that the proportions of tannin-like and carbohydrate-like groups were higher in summer, suggesting significant contribution of HULIS from biogenic secondary organic aerosols (SOAs). The higher proportions of condensed aromatic structures in winter suggested increasing anthropogenic emissions. Molecular composition analysis on the CHO, CHON, CHOS, and CHONS subgroups showed relatively higher intensities of high O-containing macromolecular oligomers in the CHO compounds in summer, further indicating stronger biogenic SOA formation in summer. High-intensity phenolic substances and flavonoids, which were related to biomass burning and polycyclic aromatic hydrocarbon (PAH) derivatives indicating fossil fuel combustion emissions, were found in winter CHO compounds. Besides, two high-intensity CHO compounds containing condensed aromatic ring structures (C9H6O7 and C10H5O8) identified in the summer and winter samples were similar to those from off-road engine samples, indicating that traffic emissions were one of the important fossil fuel sources of HULIS at the study site. The CHON compounds were mainly composed of nitro compounds or organonitrates with significantly higher intensities in winter, which were associated with biomass burning emissions, in addition to the enhanced formation of organonitrates due to high NOx in winter. However, the high-intensity CHON molecular formulas in summer were referring to N-heterocyclic aromatic compounds, which were produced from the atmospheric secondary processes involving reduced N species (e.g., ammonium). The S-containing compounds were mainly composed of organosulfates (OSs) derived from biogenic precursors, namely long-chain alkane and aromatic hydrocarbon, which illustrate the mixed sources of HULIS. Generally, different policies need to be considered for each season due to the different seasonal sources (i.e., biogenic emissions in summer and biomass burning in winter for non-fossil-fuel sources, traffic emissions and anthropogenic SOA formation in both seasons, and additional coal combustion in winter). Measures to control emissions from motor vehicles and industrial processes need to be considered in summer. Additional control measures on coal power plants and biomass burning should be applied in winter. These findings add to our understanding of the interaction between the sources and the molecular compositions of atmospheric HULIS.

Validating blueline tilefish Caulolatilus microps ages in the U.S. South Atlantic using bomb radiocarbon (F14 C).

Age validation is a critical component of an age-based stock assessment and subsequent species management. Our study used bomb radiocarbon analysis to validate age estimates of Blueline Tilefish Caulolatilus microps, a species for which regional stock assessment scientists have identified age validation as a high priority. We compared a C. microps F14 C chronology to F14 C chronologies for finfish of the U.S. South Atlantic Bight (SAB) and the north-west Atlantic. The high degree of correspondence in the chronologies exhibited for C. microps and other species of the SAB suggests a differential 14 C uptake pattern in the SAB slope waters that is likely the result of local hydrological processes that delay 14 C reaching the environments inhabited by these species. Our study was able to validate C. microps ages up to 25 years in the SAB, with strong evidence suggesting they are living to at least 50 years old.

Irrigation Systems of the Altai: Results and Prospects of Archaeological Studies

We present the fi ndings of studies concerning the irrigation systems of the Altai and outline the directions of their further exploration. Irrigation canals, widely distributed in alpine valleys and intermontane depressions, are streams of the drift type. Most are found in central Altai and in the Chulyshman River valley of eastern Altai. Complex irrigation systems were recorded in the Bilgebash and Sarduma river mouths in the Chuya valley, in the Chulcha River mouth in the Chulyshman valley, and in Tötö, the Kurai basin. Pilot excavations of the main canals showed that wooden troughs had been placed on their bottoms. Radiocarbon analysis of wood from those troughs (Cheba and Oroktoi) suggests that they date to the Late Middle Ages, and a soil sample from the bottom of the canal of the Tenga irrigation system indicates early medieval age. In the 1800s and early 1900s, canals were used by the natives mainly for watering small plots of barley, but also of wheat and rye. Agriculture has been practiced in the Altai at least since the Early Iron Age, having fl ourished, apparently, during the Early Middle Ages. The fi rst irrigation systems must have appeared together with the fi rst farmers; however, taking into account the prolonged use and modifi cations of the main canals, assessing the time of their initial construction is diffi cult.

Technical note: Intercomparison study of the elemental carbon radiocarbon analysis methods using synthetic known samples

Abstract. The accurate identification of elemental carbon (EC) sources in aerosol based on radiocarbon (14C) depends on the method of EC isolation. The lack of aerosol EC reference materials with “true” 14C values makes it impossible to evaluate the accuracy of various methods for the analysis of 14C-EC in aerosols. In this study, EC isolation methods were evaluated by using samples of mixed biomass burning, vehicle exhaust, and coal combustion. The results show that 14C-EC was not only related to the isolation method but also to the types and proportions of biomass sources in the sample. The hydropyrolysis (Hypy) method, which can be used to isolate a highly stable portion of ECHypy and avoid charring, is a more effective and stable approach for the matrix-independent 14C quantification of EC in aerosols. The 13C-ECHypy and non-fossil ECHypy values of Standard Reference Material (SRM) 1649b were −24.9 ‰ and 11 %, respectively.

The Marstrand Cannon: The earliest evidence of shipboard artillery in Europe?

Current knowledge concerning the introduction of shipboard artillery in Europe is limited. A small, muzzle-loading cast copper-alloy gun recovered off Marstrand on the west coast of Sweden may, however, provide some important leads regarding this development. Radiocarbon analysis of a piece of cloth from the powder chamber, possibly the remains of a cartouche, suggests a date for the cannon in the fourteenth century, making it probably the earliest example of European shipboard artillery found so far. In this paper we give an account of our recent investigations of this important find, which also include a geochemical analysis of the metal used for the casting of the gun.

Are crucible steel ingots isotopically homogenous? AMS radiocarbon measurements on ingots from Telangana, India

Radiocarbon analysis is increasingly used to directly date archaeological and historical metal objects, ranging from low-carbon bloomery iron to steel and cast iron. However, little is known about the isotopic homogeneity of iron-carbon alloys, particularly relating to the formation of primary cementite during crystallisation. Here, we present 14C measurements for five crucible steel ingots and one crucible steel object from Telangana in south-central India. Two of the ingots were analysed twice. The results show a very wide scatter of 14C dates, far exceeding the expected age range for this assemblage. The repeat analysis of one of the ingots gave also widely different results, indicating a fundamental problem with the 14C analysis of crucible steel. We discuss the various factors that could have influenced the measured isotopic values, including variability in raw material, sampling contamination, and fractionation during the cleaning of the metal in hot acid leading to excessive sample mass losses prior to the extraction of carbon from the metal. We argue that mass-dependant fractionation of the different carbon isotopes between austenite and cementite during solidification of the ingot, and subsequent selective dissolution of one metal phase over the other, led to a distortion of the 14C signature to seemingly older ages. We recommend further research to explore the compound-specific isotopic signature of high-carbon iron alloys and the effect of selective corrosion on such material, to reduce potential errors in 14C dating of steel and cast iron.

Subfossil oaks from riverine sediments of the Seda River in Latvia: The first results of dendrochronological and radiocarbon analysis

The article presents a dendrochronological investigation of subfossil oaks from the riverine sediments of the Seda River in the Lake Burtnieki Undulating Plain, northern Latvia. Thirty-nine oak trunks were investigated for our study. Cross-dating of samples resulted in six floating chronologies spanning 141–636 years. The longest chronology was absolutely dated to AD 652–1287 against regional oak chronologies from Lithuania, Latvia, Belarus and central European Russia. 14C dating revealed that oaks grew on the site from the last century of the third millennium cal BC to the first half of the second millennium cal AD. We assessed the depositional anomalies from two best-replicated chronologies. The germination of oaks occurred during climate warming, and dying-off phases were triggered by climate cooling and increased precipitation throughout Europe. Our results give new insights into the forest history in northern Latvia and provide a potential to construct absolute-dated millennial oak chronologies in the Baltic countries.

Microarchaeological approach to underwater stratigraphy of submerged settlements: A case study of Atlit‐Yam Pre‐Pottery Neolithic site, off the Carmel Coast, Israel

AbstractThe investigation of submerged archaeological sites faces numerous logistical challenges in the recovery of stratigraphic sequences and, as a result, is often restricted to surface deposits limiting the application of geoarchaeology. This paper outlines a new integrated field and microanalytical methodological protocol to investigate deep stratigraphic sequences (up to 2 m) within the submerged Pre‐Pottery Neolithic (PPN) site of Atlit‐Yam (9267–7970 cal. B.P. [calibrated years before the present]). A new coring method for the extraction of deep underwater stratigraphy was developed to extract three cores: two between architectural remains within the site and one outside the site. The cores were analysed using Fourier‐transform infrared spectroscopy, phytolith and pollen analysis and archaeological micromorphology to detect anthropogenic signals and undertake paleoenvironmental reconstruction. Our results indicate anthropogenic evidence at 95 cm depth based on the presence of heat‐altered sediments, high phytolith concentrations and micromorphological observations of archaeological remains. Radiocarbon analysis indicates the oldest anthropogenic layers date to the Mid Pre‐Pottery Neolithic B (PPNB) and Late PPNB (9859–9323 cal. B.P.), bearing implications for reassessing the emergence of the first coastal Neolithic villages in the Mediterranean. Our integrated field and multiproxy micro‐geoarchaeological protocol offers a new approach to detecting and studying submerged archaeological sites worldwide.

Reconstructing the oaks’ growth patterns in Greece with the use of historical timber: Case studies from Western Peloponnese

Southern Greece is a region where available oak reference chronologies are still missing, making dendroarchaeology and dating of historical buildings rather challenging, if not impossible. In the current study we performed wood identification and dendroarchaeological analysis on timber from three historical buildings: the castles of Androusa and Koroni and the Church of Agios Dimitrios, in Western Peloponnese. The three monuments represent buildings of different uses covering different periods, but also sharing a common characteristic: oak was the only timber used in their construction, while the number of preserved timber elements is very limited. A dendroarchaeological examination of these three historical buildings, together with radiocarbon and wiggle-matching analysis, provided valuable chronological information for the local archaeologists, historians, and other scientists. Application of dendrochronological techniques has helped place the three buildings under study into the Ottoman period. Our results also show that timber was acquired most probably from local non-managed forests, which suggests that oak forests were present in the broader area at least from the late 15th to the first half of the 18th centuries. The discordance between dendrochronological and radiocarbon dates in one of the three cases highlights the need for further exploration of the study area through a combined implementation of both dendrochronological and radiocarbon dating analyses in order to develop well-replicated local oak chronologies. Our study also shows that dendroarchaeology can contribute significantly to the cultural and landscape history of Western Peloponnese even with an examination of limited number of preserved timber elements from historical buildings.

Interdisciplinary analyses of the remains from three gallery graves at Kinnekulle: tracing Late Neolithic and Early Bronze Age societies in inland Southwestern Sweden

In this paper, we investigate the Scandinavian Late Neolithic and Early Bronze Age of Kinnekulle in southwestern Sweden. The above-mentioned periods in the study area are poorly understood and the archaeological record consists of a few stray finds and a concentration of 20 gallery graves. This study focuses on three of the gallery graves where commingled skeletons from successive burials were recovered. The human remains and the artefacts from the graves were used for discussing individual life stories as well as living societies with the aim of gaining new knowledge of the last part of the Neolithic and the beginning of the Early Bronze Age in southwestern Sweden. We focused on questions concerning health and trauma, mobility and exchange networks, and diet and subsistence of the people using the graves. Chronological, bioarchaeological, and biomolecular aspects of the burials were approached through the application of archaeological and osteological studies, as well as stable isotope, strontium isotope, radiocarbon, and mtDNA analyses. The study provides evidence for high mobility and diverse diets, as well as inhumations primarily dated to the transition between the Late Neolithic and Early Bronze Age. We suggest that the mountain plateau of Kinnekulle was mainly reserved for the dead, while the people lived in agriculture-based groups in the surrounding lower lying regions.

Fossil organic carbon utilization in marine Arctic fjord sediments by subsurface micro-organisms

Rock-derived or petrogenic organic carbon has traditionally been regarded as being non-bioavailable and bypassing the active carbon cycle when eroded. However, it has become apparent that this organic carbon might not be so inert, especially in fjord systems where petrogenic organic carbon influxes can be high, making its degradation another potential source of greenhouse gas emissions. The extent to which subsurface micro-organisms use this organic carbon is not well constrained, despite its potential impacts on global carbon cycling. Here, we performed compound-specific radiocarbon analyses on intact polar lipid–fatty acids of live micro-organisms from marine sediments in Hornsund Fjord, Svalbard. By this means, we estimate that local bacterial communities utilize between 5 ± 2% and 55 ± 6% (average of 25 ± 16%) of petrogenic organic carbon for their biosynthesis, providing evidence for the important role of petrogenic organic carbon as a substrate after sediment redeposition. We hypothesize that the lack of sufficient recently synthesized organic carbon from primary production forces micro-organisms into utilization of petrogenic organic carbon as an alternative energy source. The input of petrogenic organic carbon to marine sediments and subsequent utilization by subsurface micro-organisms represents a natural source of fossil greenhouse gas emissions over geological timescales.

Temporal clustering of fissural eruption across multiple segments within the Ethiopian Rift

Magmatic continental rifts show evidence that discrete rift segments experience episodic intrusive and eruptive events, more commonly termed rifting episodes. However, whether multiple rifting episodes across adjacent rift segments are clustered in time is not well understood. To address this issue, we conduct new radiocarbon dating that constrains the timing of the most recent rifting episode at the Boset magmatic segment of the northern Ethiopian rift, and combine this with historical dating of similar rifting events in the adjacent magmatic segments. New radiocarbon dates of multiple charcoal samples from the base of the most recent fissural lava at the Boset Volcanic Complex indicate that it likely occurred between 1812 and 1919 CE. These dates are similar to those from historical accounts of fissural eruption from the neighbouring Kone (∼1810 CE), and Fantale (∼1770 to 1808 CE) magmatic segments. We conduct new analysis of major and trace element compositions from these historical fissural lavas, as well as from a fresh-looking lava flow from Beru cone near to Kone volcano. The results of the geochemistry from these flows of all three magmatic segments show compositions that vary in the basalt and trachybasalt fields, with sufficient variation to rule out them having erupted from a single dike intrusion episode. This, combined with the scatter in dates from the radiocarbon analysis and historical accounts, along with the location of each eruption in a discrete and spatially offset magmatic segment, favours an interpretation of each magmatic segment experiencing separate rifting episodes but with these being clustered in time. Mechanisms to explain the clustering of rifting episodes are more speculative but could include stress transfer from dike intrusion and deep crustal hydraulic connection in the plumbing system of multiple segments.

Geological Insights on the Calcareous Tufas (Pietra Spugna) Used as Building and Ornamental Stones in the UNESCO Historical Centre of Urbino (Marche Region, Italy)

This study is addressed at the cultural heritage of the UNESCO historical centre of Urbino (Italy) through the focus on a very peculiar building and ornamental carbonate porous (spongy) stone also found in the opus quadratum Roman dry walls. For these rocks, the mathematician and historian Bernardino Baldi (16th century AD) and the mineralogist Francesco Rodolico (middle of the 20th century AD) introduced, respectively, the popular terms of Tufo spugnoso or Pietra Spugna. Physical observations and stable isotope data (δ13C and δ18O) of these rocks allowed, for the first time, their classification as calcareous tufas, thus contributing to the valorization of the stone heritage of the city. This carbonate lithotype was formed by the chemical precipitation of CaCO3, driven by the CO2 degassing of supersaturated calcium-bicarbonate-rich waters, coupled with the passive encrustations of organic material in continental environments. Radiocarbon analyses dated these stones mostly between 9100 and 4700 yr. BP when a maximum growth of these carbonate continental deposits occurred in Mediterranean regions and northern Europe, i.e., during the Holocene Atlantic climatic optimum. Work is still in progress on a perched springline of calcareous tufas found along the Metauro Valley (a few km from Urbino), being good candidates for provenance, at least for those blocks exploited by the Romans and successively reused in the architectural framework of Urbino.

Material Circularity: A Novel Method for Biobased Carbon Quantification of Leather, Artificial Leather, and Trendy Alternatives

In the past, climate change led the United Nations to define the Sustainable Development Goals Statement “blueprint to achieve a better and more sustainable future” and the European Commission to promote the “bioeconomy” concept and to launch the Green Deal Policy. Accordingly, the COP26 conference proposed a drastic reduction of fossil-based fuels and materials, in favor of biobased materials which should ensure intrinsic carbon neutrality. Contextually, many startups and established materials suppliers proposed new, trendy materials claiming sustainability advantages but, in many cases, without robust scientific backing. The need for transparency in terms of circularity led us to exploit a fast, reliable and easily deployable analytical method for assessing the biogenic carbon fraction in a variety of industrial materials. Our research team identified a radiocarbon analysis based on Saturated-absorption CAvity Ring-down (SCAR) spectroscopy as a quick and effective method for such a scope. Here we demonstrate its use for the determination of biogenic/fossil carbon proportions of polymeric and coated materials such as leather, coated textiles and trendy alternatives used in the fashion industry, with the scope of defining their intrinsic renewable content. The reliability of the SCAR method is validated through a comparison with the results obtained by the benchmark technique.

Compound-specific radiocarbon analysis of benzene polycarboxylic acids for source apportionment of polyaromatic organic matter in ambient aerosols

Polyaromatic organic matter (POM) is an important group of pollutants and light absorbers in ambient aerosols, which consists of a wide range of chemicals with fused benzene rings. POM in ambient aerosols is mainly derived from the incomplete combustion of fossil fuel and biomass. Source apportionment of POM is crucial for advising efficient mitigation of anthropogenic emissions, but that is a challenge due to the complicated composition of POM and ambient aerosols. Benzene polycarboxylic acids (BPCAs) have recently been introduced as molecular markers of atmospheric POM. Compound-specific radiocarbon analysis of BPCAs is expected to be a powerful tool for apportioning fossil sources and contemporary (i.e., biomass burning) sources of POM in ambient aerosols, yet this application is still lacking. We developed a method for radiocarbon analysis of BPCAs substituted with 3–6 carboxylic groups (B6CA, B5CA, B4CAs and B3CAs). BPCAs were isolated with preparative liquid chromatography with high recoveries (≥85%). The method is validated with reference materials with fossil and contemporary radiocarbon signatures. Successful radiocarbon analysis of BPCAs was achieved for these reference materials after correcting for the presence of average blanks (B6CA: 1.2 ± 0.2 μg, B5CA: 2.3 ± 0.6 μg, individual B4CAs: 2.7 ± 0.2 μg and individual B3CAs: 6.9 ± 0.7 μg). Source apportionment of POM based on radiocarbon analysis of BPCAs was performed for an urban dust reference material, as well as bulk aerosols and water-soluble, methanol-soluble fractions of ambient aerosols from a megacity of southern China. The results show varied contributions of fossil and contemporary sources among different POM fractions.

Radiocarbon dating of bones from archeological site Târgșoru Vechi

The early medieval settlement identified in 2019 on the west side of Târgșoru Vechi is one of the largest settlements so far investigated in Wallachia, dating from the end of the first millennium AD. Sampling for radiocarbon analysis was done from inside the houses (especially in the area of the fireplace), from the graves, as well as from one of the possible wells. Supplementary samples were also taken from a group of tombs (west-east oriented) previously studied. In this study, several pretreatment methods were applied to historical bones and teeth from the Târgșoru Vechi site, in order to remove different contaminants to ensure accurate AMS analysis. The C/N atomic weight ratio of the untreated and pretreated bones was observed to be a useful indicator for the most suitable processing method. After collagen was extracted, in the RoAMS laboratory from IFIN-HH, it was graphitized using the Automated Graphitization Equipment (AGE3) and the isotopic ratios 14C/12C, 13C/12C were measured with the 1MV Tandetron Accelerator. The radiocarbon age was in the estimated archaeological range between 1114 and 1256BP. After calendar ages were obtained, using the IntCal20 calibration curve the placement of the studied archeological site in time was confirmed, which paves the way for an extensive Târgșoru Vechi site investigation.

Recent growth increase in endemic Juglans boliviana from the tropical Andes

The spatial coverage of tree-ring chronologies in tropical South America is low compared to the extratropics, particularly in remote regions. Tree-ring dating from such tropical sites is limited by the generally weak temperature seasonality, complex coloration, and indistinct anatomical morphology in some tree species. As a result, there is a need to complement traditional methods of dendrochronology with innovative and independent approaches. Here, we supplement traditional tree-ring methods via the use of radiocarbon analyses to detect partial missing rings and/or false rings, and wood anatomical techniques to precisely delineate tree-ring boundaries. In so doing we present and confirm the annual periodicity of the first tree-ring width (TRW) chronology spanning from 1814 to 2017 for Juglans boliviana (‘nogal’), a tree species growing in a mid-elevation tropical moist forest in northern Bolivia. We collected 25 core samples and 4 cross-sections from living and recently harvested canopy-dominant trees, respectively. The sampled trees were growing in the Madidi National Park and had a mean age of 115 years old, with certain trees growing for over 200 years. Comparison of (residual and standard) TRW chronologies to monthly climate variables shows significant negative relationships to prior year May-August maximum temperatures (r = −0.54, p < 0.05) and positive relationships to dry season May-October precipitation (r = 0.60, p < 0.05) before the current year growing season. Additionally, the radial growth of Juglans boliviana shows a significant positive trend since 1979. Our findings describe a new and promising tree species for dendrochronology due to its longevity and highlight interdisciplinary techniques that can be used to expand the current tree-ring network in Bolivia and the greater South American tropics.

A Study of Silk Fabric from the Xiongnu Age Under-Headdress Discovered at Yaloman II Mound 51 in the Central Altai

We describe a large fragment of fabric from the under-headdress excavated from mound 51 at Yaloman II—a site on a high terrace near the place where the Bolshoy Yaloman fl ows into the Katun, Central Altai. Various criteria, including radiocarbon analysis, suggest that the burial dates to the Xiongnu Age (200 BC to 100 AD). The structure of the textile was assessed microscopically. On the basis of morphological criteria, the fi bers were identifi ed as silk. The fabric is described according to the accepted international standards. Results attest to the use of a treadle loom for producing polychrome silk fabric, from which the early nomads sewed a headdress in the form of a cap or bonnet. Such a prestigious material was produced in limited quantities in China to decorate details of clothing worn by the elite. Decorative silk items could have been imported from there to the Altai as gifts received by the leader of the nomadic Xiongnu Empire in Inner Asia. The Altai was part of this empire, as demonstrated by the entire assemblage of funerary items from Yaloman II.

The ‘old wood’ effect and problems of dating iron smelting sites

The paper is aimed at the analysis of the ‘old wood’ effect in radiocarbon chronology of iron smelting com-plexes of South Siberia. The production sites are here set outside the settlements, and radiocarbon dating re-mains the only means of their chronological attribution. With the example of Kuyahtanar metallurgical site in the Mountain Altai, we show that the range of a series of radiocarbon dates obtained for the same iron-smelting fur-naces can span a thousand years. It has been established that such a chronological range can be explained by the use of wood from long-lived tree species for charcoal production and the resulting significant apparent age due to the ‘old wood’ effect. The essence of the effect consists in that as a tree grows, its inner annual rings die out and stop exchanging carbon with the environment, while the tree is still alive. Therefore, the pith of a long-lived tree is much older than its outer rings, and radiocarbon analysis determines not the age of the archaeologi-cal object, or time when the tree was cut, but the date of the death of that part of the tree which was sampled for the dating. Methodological recommendations have been drawn up capable of minimizing the impact of the ‘old wood’ effect in the dating of iron metallurgy sites. During the sampling, it is recommended to collect fragments of char-coal from the tree outer rings. In a case, where this is not possible, it is necessary to obtain a series of at least three dates for one site. In such a series, the latest of the three dates will be the closest to the age of the archaeological object. It is also necessary to determine the tree species used for burning the charcoal for smelting. After the tree species is identified, it becomes possible to infer its average and maximum life expectancy in the specific natural and climatic conditions, and, consequently, possible average and maximum impact of the ‘old wood’ effect. Since in the case of dating metallurgical sites the impact of the ‘old wood’ effect is virtually unavoidable, it is suggested that, in the future, the chronology of the complexes radiocarbon dated with a single sample of charcoal is revisited.