In order to test the accuracy of accelerator mass spectrometry (AMS) radiocarbon dating of pollen, 8 samples of pollen concentrates and 4 bulk organic samples were collected and analyzed from trench T1041 at the Tianluoshan site, Yuyao city, Zhejiang Province. This site was chosen because a reliable chronology had been previously established there based on radiocarbon dates of plant materials. The pollen concentrate samples were measured using AMS 14C and the 4 bulk organic samples were measured by liquid scintillation counting (LSC). The pollen concentrates and bulk organic samples yield ages that are a few hundred years to thousands of years older than those from plant materials, respectively. Contributions from reworked sediments can explain the older ages for the pollen concentrates and sediment organic dates. This study suggests that caution must be exercised when discussing millennial- or centennial-scale climate events based on chronologies that are controlled by age determinations of pollen concentrates.

There have been a number of studies that have attempted to estimate the past radiocarbon reservoir effects in Qinghai Lake, China. This article reports on measurements on modern samples collected at the lake in October 2003 and October 2009, which allow us to better understand the systematics of the lake and shed new insights on the processes occurring in the lake. The results indicate that atmospheric exchange of 14C is the main process affecting surface dissolved inorganic carbon (DIC) in the lake, but dissolved organic carbon (DOC) can be explained as a combination of sources. We also conclude that sediment carbon can be explained by a model where input from the surrounding rivers and groundwater are important, in agreement with the model of Yu et al. (2007).

The rapid outward and upward growth of the world's large fluvial sedimentary systems during the second half of the Holocene is a remarkable geologic process that may have buried considerable areas of pre-existing riparian wetlands, which in turn would sequester massive carbon. However, the role of floodplain lakes in the global carbon budget has long been neglected. This article demonstrates the potential of organic carbon burial due to floodplain aggradation during the late Holocene by analyzing a sediment core from a buried floodplain lake in the lower Yellow River area. Based on detailed radiocarbon dating, this study inferred that landscape development in the study area has experienced three disparate stages closely related to the displacement of the lower Yellow River channel. The first stage (∼2250–1700 cal yr BP) represents a widespread pedogenic process while the Yellow River discharged to the northern Bohai Sea through a course much farther north from the present-day position. The subsequent stage (∼1700–1000 cal yr BP) broadly corresponds to the calm period of the Yellow River while it discharged to the southern Bohai Sea through a course slightly north from the present-day position. A lacustrine environment prevailed during this period, sequestering organic carbon at a rate of ∼0.58 kg m 2 yr 1. The final stage (∼1000 cal yr BP to present) is marked by the rapid growth of the floodplain due to the frequent rerouting of the lower Yellow River. This analysis suggests that fluvial sedimentary systems should be integrated into the terrestrial carbon budget when accounting for the aberrant rise of the atmospheric CO2 in the face of global cooling during the second half of the Holocene.

This article compares radiocarbon dates and the stratigraphic matrix obtained from excavations at the Piedras Blancas archaeological site, Ambato Valley, NW Argentina. Analysis revealed inconsistencies between 14C dates and certain events that can be clearly identified in the stratigraphy of the site. This fact led first to recognize the importance of a detailed stratigraphic record to allow a point of control and comparison. Secondly, this article discusses for the present case, (a) the consistency shown by the dating performed on bone materials in relation to the stratigraphic matrix and (b) the inconsistencies identified in relation to the dating performed on charred plant material, although this type of material was chosen for collection and dating using all appropriate caution to prevent dating bias. Finally, the possibility is considered that the dated plant materials could be affected by the high microcharcoal concentrations observed in the valley's sediments as the result of fire regimes with a high frequency, which seem to have existed since at least about 4000 BP.

Dispilio is the only excavated Neolithic lakeside settlement in Greece. Archaeological research provided evidence that the site was continuously used from the Early Neolithic (∼6000 BC) to the Late Chalcolithic period (∼1200 BC, Mycenaean period). During several archaeological campaigns, a portion of the settlement has been excavated that enabled a sufficient understanding of the architectural layout of homes, the building materials, and the organization of space, while the finds (fragments of pottery, stone and bone tools, anthropomorphic and zoomorphic clay figurines, miniature representations of objects also on clay, animal and fish bones, charred cereal grains, and other fruits) provided information on the everyday lives of the Neolithic inhabitants. A series of charcoal and wood samples, originating mostly from the Middle and Late Neolithic layers of the site, were radiocarbon dated and their dates range from ∼5470 to 4850 BC. The most unexpected of the finds, a wooden tablet from the lake bearing engraved symbols, was 14C dated to 5260 ± 40 BC. In addition, clay tablets and pottery vessels engraved with similar symbols were also unearthed from layers dated to the same period. If this proves to be a primary source of written communication, the history of writing should be reconsidered and Neolithic societies should not be considered “societies without writing.”

Absolute dates for the end of the Early Bronze Age ancient Near East are of crucial importance for assessing the nature and extent of mid- to late 3rd millennium BC transitions in the Near East and their alleged link to the 4.2ka BP climatic event. This article presents a radiocarbon sequence for the Early Bronze Age site of Tell Fadous-Kfarabida (Lebanon) and argues that the end of the Early Bronze III period has to be dated considerably higher than previously estimated. There is no reason to assume that the 4.2ka BP event might have contributed to or even triggered the collapse of the first urban cities in the southern and central Levant.

In the last decade, the myth of the pristine tropical forest has been seriously challenged. In central Africa, there is a growing body of evidence for past human settlements along the Atlantic forests, but very little information is available about human activities further inland. Therefore, this study aimed at determining the temporal and spatial patterns of human activities in an archaeologically unexplored area of 110,000 km2 located in the northern Congo Basin and currently covered by dense forest. Fieldwork involving archaeology as well as archaeobotany was undertaken in 36 sites located in southeastern Cameroon and in the northern Republic of Congo. Evidence of past human activities through either artifacts or charred botanical remains was observed in all excavated test pits across the study area. The set of 43 radiocarbon dates extending from 15,000 BP to the present time showed a bimodal distribution in the Late Holocene, which was interpreted as two phases of human expansion with an intermediate phase of depopulation. The 2300–1300 BP phase is correlated with the migrations of supposed farming populations from northwestern Cameroon. Between 1300 and 670 BP, less material could be dated. This is in agreement with the population collapse already reported for central Africa. Following this, the 670–20 BP phase corresponds to a new period of human expansion known as the Late Iron Age. These results bring new and extensive evidence of human activities in the northern Congo Basin and support the established chronology for human history in central Africa.

The paleoclimatic signal of Lake Hovsgol in Mongolia was investigated using authigenic beryllium isotopes from 20 sediment samples. The beryllium isotopic records from this study indicate that there were three dry and cold periods at the lake around 9400, 12,700, and 17,100 cal yr BP. The significant 10Be signal during the Younger Dryas (YD) period is found to be lower. This indicates that the Lake Hovsgol area was subject to a period of cold and dry conditions with minimal dust input, which manifests itself as a low 9Be profile in this study. In warmer and wetter climatic conditions, the 10Be concentration was found to be higher, and this agrees with the sedimentation record of this study. The climatic signals from Lake Hovsgol appear to be similar to a decreased beryllium record during the deglacial period. The results of this study confirm that the Lake Hovsgol area also experienced the global paleoclimatic change associated with the YD event around 12,700 cal yr BP. Further investigation using worldwide lake records by the analytical technique of authigenic beryllium will be useful for understanding the global paleoclimatic change pattern in conjunction with lake-level change.

Megiddo (Israel) is a key site for the study of the stratigraphy, chronology, and history of the Bronze and Iron ages in the Levant. The article presents a Bayesian chronological model for seven ceramic typology phases and 10 stratigraphic horizons at this site, covering the Late Bronze and much of the Iron Age. The model is based on 78 samples, which provided 190 determinations—the most thorough set of radiocarbon determinations known so far in a single site in the Levant. This set of data provides a reliable skeleton for the discussion of cultural processes and historical events in the region and beyond, including the periods of the Egyptian Empire in Canaan and the Northern Kingdom of Israel.

This article presents a set of Late Pleistocene marine mollusk radiocarbon (AMS) age estimates of 30–50 14C kyr BP, whereas a MIS5 age (>75 ka) is indicated by quartz and feldspar OSL dating, biostratigraphy, U-Th dating, and age-depth relationships with sea level. These results indicate that the 14C dates represent minimum ages. The age discrepancy suggests that the shells are contaminated by younger carbon following shell death. The enigmatic 14C dates cannot be “solved” by removing part of the shell by stepwise dissolution. SEM analysis of the Late Pleistocene shells within a context of geologically younger (recent/modern, Holocene) and older (Pliocene) shells shows the presence of considerable amounts of an intracrystalline secondary carbonate precipitate. The presence of this precipitate is not visible using XRD since it is of the same (aragonitic) polymorph as the original shell carbonate. The combination of nanospherulitic-shaped carbonate crystals, typical cavities, and the presence of fatty acids leads to the conclusion that the secondary carbonate, and hence the addition of younger carbon, has a bacterial origin. As shell material was studied, this study recommends an assessment of possible bacterial imprints in other materials like bone collagen as well.

Late Neolithic graves excavated at Tell Sabi Abyad, Syria, have been dated by radiocarbon. This series of 46 human bone dates represents a sequence of cemeteries that is analyzed by Bayesian methodology. The dates show continuous use of the northeastern slope of the mound as a burial ground throughout the Initial Pottery Neolithic to the Halaf period.

This article presents accelerator mass spectrometry (AMS) radiocarbon dates of organic inclusions of cement materials from the House XVII-XVIII Complex located in the Umm el-Jimal archaeological site, east Jordan, aiming at refining the unclear chronology of the house. Fine straws and small fragments of charcoal uncovered from preserved architectural lime mortars and plasters were dated without carrying out extensive excavations. The results indicate that the house most probably was initially plastered or built during the middle of the Byzantine period. The results agree with the historical and archaeological data indicating that Umm el-Jimal flourished during this period; therefore, it is probable that the house was established during this time to meet the housing demand for the increased number of its population.

Current conventions for reporting radiocarbon determinations do not cover the reporting of calibrated dates. This article proposes revised conventions that have been endorsed by many 14C scientists. For every determination included in a scientific paper, the following should apply: (1) the laboratory measurement should be reported as a conventional radiocarbon age in 14C yr BP or a fractionation-corrected fraction modern (F14C) value; (2) the laboratory code for the determination should be included; and (3) the sample material dated, the pretreatment method applied, and quality control measurements should be reported. In addition, for every calibrated determination or modeled date, the following should be reported: (4) the calibration curve and any reservoir offset used; (5) the software used for calibration, including version number, the options and/or models used, and wherever possible a citation of a published description of the software; and (6) the calibrated date given as a range (or ranges) with an associated probability on a clearly identifiable calendar timescale.

In situ radiocarbon inorganic production and retention pathways are distinct from those of the more commonly used traditional organic/atmospheric 14C. In addition, a growing number of laboratories are extracting in situ cosmogenic 14C from quartz, using a variety of analytical techniques. As such, a flexible yet internally consistent set of procedures for data reduction that recognizes the unique nature of the in situ14C system is essential for reliable comparison of results among laboratories. This article thus presents a brief data reduction framework that can accommodate differences in both AMS and laboratory analytical techniques.

For over 2 decades, there have been calls for Polynesian archaeologists to identify radiocarbon samples to taxon and material type, and preferentially date short-lived materials. This stems from recognition that even modest amounts of inbuilt age are problematic in this oceanic region where human settlement dates to the last 3 millennia or less. Despite programmatic statements to this effect, and empirical demonstrations of value, uptake of these practices has been slow. This article suggests that short-lived materials be defined as those with lifespans of 10 yr or less, recognizing that reducing the distance between target event and the dated material is an ongoing aim for archaeology. We identify both short-lived materials that are suitable for dating and long-lived species (>75 yr) that should be avoided given their potential for inbuilt age. Additionally, we suggest that given the destructive nature of 14C dating there is value to (1) obtain high-resolution photographs of samples prior to analysis, (2) split samples and archive residuals when possible, and (3) routinely report the tools and expertise used in identification. Past and recent dating analyses at a Polynesian site in the southern Cook Islands are used to illustrate how the suggested protocols might enhance current and future studies. We also establish that mature Calophyllum inophyllum, a common coastal tree and valued timber species, has been in the southern Cook Islands for at least the last 700 yr and is likely to be indigenous and long-lived.

The University of Bern has set up the new Laboratory for the Analysis of Radiocarbon with AMS (LARA) equipped with an accelerator mass spectrometer (AMS) MICADAS (MIni CArbon Dating System) to continue its long history of 14C analysis based on conventional counting. The new laboratory is designated to provide routine 14C dating for archaeology, climate research, and other disciplines at the University of Bern and to develop new analytical systems coupled to the gas ion source for 14C analysis of specific compounds or compound classes with specific physical properties. Measurements of reference standards and wood samples dated by dendrochronology demonstrate the quality of the 14C analyses performed at the new laboratory.

Radiocarbon is an exceptionally useful tool for studying soil-respired CO2, providing information about soil carbon turnover rates, depths of production, and the biological sources of production through partitioning. Unfortunately, little work has been done to thoroughly investigate the possibility of inherent biases present in current measurement techniques, like those present in δ13CO2 methodologies, caused by disturbances to the soil's natural diffusive regime. This study investigates the degree of bias present in four 14C sampling chamber methods using a three-dimensional numerical soil-atmosphere CO2 diffusion model. The four chambers were tested in an idealized, surrogate reality by assessing measurement bias with varying Δ14C and δ13C signatures of production, collar lengths, soil biological productivity rates, and soil diffusivities. The static and Iso-FD chambers showed almost no isotopic measurement bias, significantly outperforming dynamic chambers, which demonstrated biases up to 200‰ in some modeled scenarios. The study also showed that 13C and 14C diffusive fractionation are not a constant multiple of one another, but that the δ13C correction still works in diffusive scenarios because the change in fractionation is not large enough to impact measured Δ14C values during chamber equilibration.

A primary concern with dating skeletal material from oceanic environments is the effect of marine-derived carbon on resulting radiocarbon ages. Due to uncertainties in local marine reservoir effects and the proportion of marine carbon incorporated in bone, dates from archaeological skeletal material exhibiting marine dietary signatures have previously been characterized as problematic and removed from further analysis. While in certain instances this may be appropriate, in others it is not. This article presents 26 new 14C dates obtained from human teeth (dentin collagen) on Rapa Nui. The effect of the local marine reservoir on 14C ages is evaluated assuming a range of incorporated marine-derived carbon. The results indicate that the Rapa Nui 14C ages are not significantly different under varying realistic extreme ranges in estimates of the proportion of marine carbon consumed. The article argues that this is primarily due to the small local marine reservoir effect measured in Rapa Nui and relatively lower reliance on marine resources in the prehistoric and protohistoric population.

A rapid yearly increase in the radiocarbon content has been detected for the period from AD 993 to 994. However, this event is supported by the 14C measurements of only one cedar tree sample, and verification is necessary to confirm this event more reliably. For this purpose, this study measured the 14C content in Japanese Hinoki tree rings corresponding to the period from AD 988 to 997 using the accelerator mass spectrometry system at Yamagata University (YU-AMS). The result shows a significant 14C increase from AD 993 to 994, and is consistent with the previously measured data for the Japanese cedar tree. This marks the second case detecting an increased 14C level corresponding to the AD 994 event.

The SUERC Radiocarbon Dating Laboratory has recently replaced its spreadsheet-based record keeping with a new database program, custom designed to help laboratory staff manage the high throughput of nearly 5000 cathodes in the past year. The system can accept data from a variety of sources in addition to manual entry; experimental results can be uploaded from spreadsheets, while integration with graphitization lines means that graphite yields are automatically recorded. The system is able to pass 14C results directly to OxCal v 4 for calibration, with the resulting plots incorporated into the dating certificates issued to submitters. There are also benefits to submitters, with electronic sample submission both eliminating transcription errors and speeding up the logging-in process, which keeps turnaround times down. For bone samples, data on collagen yields are now stored electronically and are more readily obtainable from the laboratory. The new SUERC Radiocarbon Dating Laboratory database will make a significant contribution to maintaining the high quality of results produced by the laboratory, aiding staff in tracking sample progress, and monitoring quality assurance (QA) samples going through the laboratory, eliminating transcription errors, and making communication easier between laboratory staff and sample submitters.