The issue of contamination in radiocarbon dating is well known and can affect not only archaeological findings but also artworks. In the latter case, a possible source of contamination is represented by the products used during the restoration, e.g. resins of synthetic origin like the well-known Paraloid, applied to wood artifacts as a strengthening and preserving agent. In the case of incomplete removal prior to dating, the resins produce an apparent aging of the samples. Mechanical cleaning using traditional tools and the standard pretreatment acid-base-acid (ABA) protocol are not sufficient to remove such contaminants, while the use of organic solvents, in particular petroleum solvents and chlorine-based products, can be effective. However, the most widely used protocol, based on the Soxhlet extraction system, is very time consuming. Here, in the presence of chloroform-soluble applied products, like the widespread Paraloid B-72, this study proposes the use of a new easily operated pretreatment procedure, developed at INFN-LABEC in Florence, based on the use of chloroform (CHCl3) as solvent and on a simple extraction. First, the effectiveness of this procedure was checked by applying it to remove the resin from wood samples of known age, which had been previously intentionally contaminated by applying large quantities of Paraloid. 14C AMS measurements performed on the test samples before and after contamination and application of the proposed procedure proved its effectiveness for removal, while this was not the case when applying standard ABA protocols. Fourier transform infrared (FTIR) spectroscopy analyses also were used to check the removal of contaminants. The new procedure was applied in two case studies: the wood frame of an altar piece from the Renaissance and a painting on canvas from the early 20th century. For both artworks, the use of synthetic resins was documented in restorations performed a relatively long time ago: the wood frame was restored using just Paraloid, the canvas using a thermoplastic polymer soluble in chloroform. Enough time elapsed for the resins to create cross-linking bonds with the original material. Despite this, the results obtained by 14C AMS dating confirm the reliability of the new chloroform-based pretreatment in removing the contaminations. Also in these cases, spectroscopic techniques were used to compare the effectiveness of the ABA and the new treatments in removing the contaminants.

The determination of the age of tropical trees and palms is of significant importance for ecological studies and designing sustainable forest management plans. Radiocarbon is a powerful tool that can potentially help the determination of ages and growth rates of these plants. However, the application of 14C analyses has one important problem for trees without annual rings and palms: the calibration of 14C measurements with common programs such as CALIBomb or OxCal gives erroneous determinations for wood formed between AD 1954 and 1964. This problem is illustrated here using samples from a tropical tree (Otoba gracilipes) and a tropical palm (Oenocarpus bataua). This study shows how the use of two adjacent samples can help to unambiguously determine the real age of the samples and their mean growth rates. For comparison, long-term growth measurements for both species were used and it was determined that 14C analyses provide accurate determination of growth rates for tropical trees and palms. Furthermore, the application of 14C analyses in palms allows the determination of the rosette stage, rarely quantified in forest inventories and life-history studies.

Dendrochronological research in North-Central Europe and the East Mediterranean has produced networks of long regional oak (Quercus sp.) reference chronologies that have been instrumental in dating, provenancing, and paleoclimate research applications. However, until now these two important tree-ring networks have not been successfully linked. Oak forests and historical/archaeological sites in southeastern Europe provide the key for linking the North-Central European and East Mediterranean tree-ring networks, but previous dendrochronological research in this region has been largely absent. This article presents the initial results of a project, in which we have built oak tree-ring chronologies from forest sites and historical/archaeological sites along a north-south transect between Poland and northwestern Turkey, with the aim of linking the North-Central European and East Mediterranean tree-ring networks and creating a new pan-European oak data set for dendrochronological dating and paleoclimatic reconstruction. Correlation among tree-ring chronologies and the spatial distribution of their teleconnections are evaluated. The southeastern European chronologies provide a solid bridge between both major European dendrochronological networks. The results indicate that a dense network of chronologies is the key for bridging spatial and temporal gaps in tree-ring records. Dendrochronological sampling should be intensively continued in southeastern Europe because resources for building long oak chronologies in the region are rapidly disappearing.

Lime burials are a characteristic phenomenon of the protohistoric funerary tradition on the Balearic Islands. At Cova de Na Dent, a lime burial has been sampled for analysis. The lime burial was made up of lime and fragmented bones. Six layers were sampled and described in the laboratory according to their color, the consistency of the deposition, and the aspect and quantity of the bone fragments. Bone samples and lime were dated. The lime was analyzed by using petrographic analysis, X-ray diffraction, FTIR spectroscopy, and simultaneous thermal analysis. The results show that the bones were cremated in the presence of crushed rock carbonate. The 14C dates on the lime suggest an earlier chronology for this ritual, starting in the Bronze Age, as generally is accepted.

In forensic sciences, radiocarbon found in modern human nails and hair is evaluated to determine the year of death. However, 14C analyses presented herein of fingernails and hair from the same infant demonstrated 14C values of hair that were lower than would be expected (e.g. depleted relative to the fingernails by at least 10‰). These results prompted a series of 14C measurements on infant hair strands, fingernails, and infant shampoo, which suggested the presence of C contamination due to cosmetic products. To further evaluate these discrepancies, several hair strands and fingernail samples from multiple donors were collected, pretreated by several approaches, and measured using isotopic analysis (δ13C, δ15N, and C/N as well as 14C accelerator mass spectrometry). SEM images of the surface of chemically pretreated hair strands were also taken to inspect the performance of the chemical pretreatments applied. Our 14C and stable isotope results show that modern human hair is likely contaminated with fossil-fuel-derived carbon, which is found in most hair care products. Currently, the various chemical pretreatments available in the literature and presented herein show that it is not possible to completely remove foreign carbon contaminates. Thus, the human 14C and δ13C values between keratinous tissues (fingernails and hair) arc not in agreement. From these observations, it becomes apparent that isotopic interpretations using human hair should be used with extreme caution and additional work is needed for its use in forensic and dietary research.

Radiocarbon dates, obtained from different human bones found in several tombs of the site of Son Peretó, are presented and discussed together with the stratigraphical evidence and the study of the material culture. The calibrated dates show that the tombs were built earlier than the main phase of occupation of the West Sector, therefore belonging to a necropolis linked to the Christian building prior to the transformation of the area into a habitation nucleus. The necropolis is 14C dated mainly to the 6th century AD. This is in good agreement with the chronology provided by ceramic materials.

The freshwater reservoir effect (FRE) hypothesis suggests that ancient carbon from aquatic organisms incorporated into AMS-dated charred, encrusted cooking residues on interior pottery walls produces old apparent radiocarbon ages. This hypothesis has been used primarily in northern European final Mesolithic contexts to explain 14C ages on cooking residues that are thought to be too old relative to 14C ages obtained on terrestrial samples, resulting in so-called freshwater reservoir offsets (FROs). More recently, the hypothesis has been cited in interpretations of 14C ages from residues in the North American Plains and elsewhere. This article presents a model using an Excel spreadsheet that allows calculation of FROs with varying inputs of dead carbon and aquatic and terrestrial resources.

A total of 272 oak (Quercus sp.) samples have been collected from large subfossil trees dredged from sediment deposited by the Sava and various tributary rivers in the Zagreb region of northwestern Croatia, and in northern Bosnia and Herzegovina. Measurement series of tree-ring widths from these samples produced 12 groups, totaling 3456 years of floating tree-ring chronologies spread through the last ca. 8000 years. This work represents the first step in creating a new, high-resolution resource for dating and paleoenvironmental reconstruction in the Balkan region and potentially a means to bridge between the floating tree-ring chronologies of the wider Mediterranean region and the continuous long chronologies from central Europe.

The prehistoric site of Cornia Nou (Menorca) features a number of well-preserved architectural structures belonging to the Talayotic culture. Over the last 6 yr, a team linked to the Museum of Menorca has conducted an archaeological excavation project of a large rectangular building attached to the south side of a substantial and massive talayot, which is considered the western talayot. The main objective of this paper is to present the chronological framework of this building, specifying the period of use and the time of abandonment of the building, as well as the dating of the different phases of its construction. A total of 27 14C analyses were obtained from samples of the stratigraphic layers and architectonic structures inside the South Building (SB). This research has provided new insights concerning the early stages of the Talayotic culture. The 14C dates allow us to place the first recorded occupation phase of the SB in an interval dated within 1100–900 BC (phase 4). A second phase in the occupation of the SB dates to ∼900–800 BC (phase 5). A final occupation phase could be situated between 800–600 BC (phase 6). However, this record provides evidence to suggest that the construction of the west talayot may pertain to a time before the beginning of the 1st millennium cal BC.

Dendroclimatology in the Eastern Mediterranean (EM) region has made important contributions to the understanding of climate variability on timescales of decades to centuries. These contributions, beginning in the mid-20th century, have value for resource management, archaeology, and climatology. A gradually expanding tree-ring network developed by the first author over the past 15 years has been the framework for some of the most important recent advances in EM dendroclimatology. The network, now consisting of 79 sites, has been widely applied in large-scale climatic reconstruction and in helping to identify drivers of climatic variation on regional to global spatial scales. This article reviews EM dendroclimatology and highlights contributions on the national and international scale.

The Laschamp excursion is a period of reduced geomagnetic field intensity occurring 40.7 ± 1.0 kyr ago. As a consequence, cosmogenic isotope production increased dramatically and its sensitivity to solar activity was enhanced during this period. The latter occurs because a larger fraction of the lower-energy interstellar galactic cosmic-ray particles, normally excluded by the geomagnetic field, is able to reach Earth's atmosphere. This produces a cosmogenic isotope production signal with a significant structure. As high-resolution 10Be profiles from both Antarctica (EDC) and Greenland (NGRIP-GRIP) during this crucial period are now available, one can use them as input into a box carbon cycle model in order to predict atmospheric 14C variations due to the Laschamp excursion. For this purpose, 10Be data are converted into 14C, using production calculations for the 10Be-14C conversion, after correction for the estimated difference of sensitivity between polar and global 10Be deposition. Several scenarios of carbon cycle state are simulated, from preindustrial to glacial conditions. Applying two recent cosmogenic isotope production calculations for the 10Be to 14C conversion, we found that the resulting atmospheric Δ14C variations are very sensitive to which of these two are employed. For example, Δ14C amplitude under glacial conditions varies from 260‰ (EDC) and 320‰ (Greenland) to 430‰ (EDC) and 510‰ (Greenland) depending on the formulation used for 10Be-14C conversion.

Thirty-three paired accelerator mass spectrometry (AMS) radiocarbon dates on human and terrestrial faunal remains from the same Neolithic and Early Bronze Age graves are used to develop a correction for the freshwater reservoir effect (FRE) at Lake Baikal, Siberia. Excluding two outliers, stable nitrogen isotope (δ15N) values show a positive correlation (r2 = 0.672, p < 0.000) with offsets in 14C yr between paired human and fauna determinations. The highest offset observed in our data set is 622 yr, which is close to the value of ∼700 yr suggested for endemic seals in the lake. For each per mil increase in δ15N, the offset increases by 77 ± 10 yr in the overall data set. However, there are indications that different regression models apply in each of two microregions of Cis-Baikal. In the first, sites on the southwest shore of the lake and along the Angara River show a strong positive correlation between δ15N values and offsets in 14C yr (r2 = 0.814, p < 0.000). In the other, the Little Sea, both δ13C and δ15N values make significant contributions to the model (adjusted r2 = 0.878; δ13C p < 0.001; δ15N p < 0.000). This can be related to the complex 13C ecology of the lake, which displays one of the widest ranges of δ13C values known for any natural ecosystem. The results will be important in terms of refining the culture-history of the region, as well as exploring the dynamic interactions of hunter-gatherer communities both synchronically and diachronically.

Radiocarbon dates on samples susceptible to inbuilt age are common in the chronological record of many archaeological and environmental sites. Indeed, fragments of charcoal and wood are sometimes the only materials sufficiently well preserved for dating. However, where high-precision estimates arc required the extra uncertainty associated with such measurements often renders them unusable. This article tests three Bayesian modeling approaches that are designed to tackle this problem. The findings of our study suggest that successful corrections can be made for the inherent age offsets. The most effective and versatile approach was based on a version of outlier analysis. It is hoped that this method will become more widely employed and enable samples susceptible to inbuilt age to be included in high-precision chronologies.

This article presents a late summer temperature reconstruction (AD 1675–1980) for the northeastern Mediterranean (NEMED) that is based on a compilation of maximum latewood density tree-ring data from 21 high-elevation sites. This study applied a novel approach by combining individual series from all sites into one NEMED master chronology. This approach retains only the series with a strong and temporally robust common signal and it improves reconstruction length. It further improved the regional character of the reconstruction by using as a target averaged gridded instrumental temperature data from a broad NEMED region (38–45°N, 15–25°E). Cold (e.g. 1740) and warm (e.g. 1945) extreme years and decades in the reconstruction correspond to regional instrumental and reconstructed temperature records. Some extreme periods (e.g. cold 1810s) reflect European-wide or global-scale climate conditions and can be explained by volcanic and solar forcing. Other extremes are strictly regional in scope. For example, 1976 was the coldest NEMED summer over the last 350 years, but was anomalously dry and hot in northwestern Europe and is a strong manifestation of the summer North Atlantic Oscillation (sNAO). The regional NEMED summer reconstruction thus contributes to an improved understanding of regional (e.g. sNAO) vs. global-scale (i.e. external) drivers of past climate variability.

This article presents new radiometric data from archaeological layers of the inhabited structures adjacent to the cyclopean monument of Cap de Forma (Mahon, Menorca). The archaeological site is located on a narrow isthmus that links a 30-m-high coastal promontory to the mainland. It is next to an excellent natural harbor on the south coast of the island. The protohistorical complex consists of a cyclopean monument surrounded by a necropolis of rock-cut tombs (cuevas) that are dug into the cliff. The monument is an atypical example of Talayotic architecture. The excavations carried out since 1997 have discovered three living spaces. These lean against the southern wall of the cyclopean structure. The artifacts are almost all pan of a chronological horizon that corresponds to the beginning of the Talayotic period. This study uses radiometric data to help interpret the recent findings from the three living spaces that flank the wall of the central monument.

This study applied compound-specific radiocarbon analysis (CSRA) to a 186-m-long sediment core (U1357A) taken from Adélie Basin located on the continental shelf off Wilkes Land, East Antarctica. The CSRA targeted C16 fatty acid as well as C16., fatty acid and cyclopheophorbide-a-enol isolated from the sediment. Due to their high degradation rate, these compounds are expected to occur in low abundances in relict organic matter deposited at this site. Twelve compound-specific (CS) 14C ages were obtained that are mostly consistent with their stratigraphic order. The CS 14C results of all samples are Holocene in age (9800 to 440 cal BP). These results suggest that significant sedimentation started ∼10,000 cal BP. Moreover, the data suggest that 14C measurements of C16:1 fatty acid and cyclopheophorbide-a-enol are useful for dating sediments from the Southern Ocean.

This contribution of the absolute chronology for the Beaker culture presents the results of archaeological research that took place at Coval Simó (Mallorca) between 1998 and 2008. Coval Simó is a rockshelter situated at the summit of one of the mountains that forms part of the northern mountain range of the Serra de Tramuntana. The site provided an exceptional undisturbed context, shielding a small space of only 25 m2. Thin sedimentary layers were deposited in a short timespan and later were sealed off by large blocks due to a rockslide falling from the top of the rockshelter. This site has offered significant information related to the occupation of a human group linked to the Bell Beaker culture, and users of other distinctive undecorated pottery vessels. Direct evidence of early island metallurgy was also obtained: smelting slags from local copper minerals. Regarding the methodology used for analysis, short-lived samples were chosen for radiocarbon dating, consisting of bone fragments identified and classified taxonomically. The samples were submitted alternately to two different 14C laboratories and the obtained results point to a clear horizon for the early human occupation of the site, ranging between about 2300 and 1900 cal BC.

The eastern Adriatic is a key area for understanding the mechanisms and effects of the spread of agriculture. This article presents an accelerator mass spectrometry (AMS) radiocarbon chronology for the introduction and subsequent development of farming villages on the eastern shore of the Adriatic (∼6000–1700 cal BC) and evaluates this in comparison with the established pottery chronology based on stylistic data from Pokrovnik (Drniš) on the Dalmatian coast of Croatia. Models for the spread of agriculture rely heavily on changing pottery styles to define cultural groups and trace geographic relationships. Based on AMS 14C dates presented here, Impressed Wares first appear in central Dalmatia by 6000 cal BC and persist until 5300 cal BC, well into what is generally termed the Middle Neolithic. Similarly, a typical Middle Neolithic ware, figulina, appeared earlier than anticipated. These findings stand in contrast to cave and rockshelter assemblages in the eastern Adriatic, but mirror assemblages from farming villages on the Italian Adriatic coast. This study argues that the similarities in ceramic assemblage composition and change through time may have less to do with direct contacts between areas, but more with the nature of ceramic production and consumption at village sites in general. These data shed light on the limitations of regional ceramic chronologies in the eastern Adriatic and highlight the necessity for systematic expansion of 14C chronologies to address the social, economic, and ecological relevance of early farming in the Adriatic for the spread of agriculture in Europe and the Mediterranean.

The Tellervo dendrochronological software builds upon the Tree-Ring Data Standard (TRiDaS) to provide a tool for recording and managing all manner of dendrochronological data. However, Tellervo is especially useful for dendroarchaeological research. The traditional file formats used in dendrochronology—and by association the applications that use them—have very limited and nonstandard methods for recording rich information about dendro samples and their context. Such information is especially important in dendroarchaeological research to ensure accurate conclusions are made. Tellervo is described here in the context of research carried out as part of the excavations of the Theodosian Harbor at Yenikapı, Istanbul.

Four fen peat sequences in northern Finland were dated by the accelerator mass spectrometry (AMS) radiocarbon method in order to study past peatland dynamics and carbon accumulation patterns. Initially, plant macrofossils were used for dating. However, the dates were severely disordered, with marked inversions in all sequences. In one 140-cm peat core, for example, all ages fell within a ∼1000-yr time window. Following these unreliable results, a few bulk peat samples were dated to help assess if any of the plant macrofossil-derived dates were reliable. Bulk dates did not help to solve the problem. This study evaluates the possible sources of error but is unable to single out one clear cause. It is probable that many factors related to the fen environment, such as flooding and root intrusion, may have contributed to the errors. Peat plant macrofossils and bulk peat samples are considered to be reliable dating materials, but the examples given herein highlight the difficulties that can be associated with AMS dating of peat samples.