The freshwater reservoir effect is a potential problem when radiocarbon dating fish bones, shells, human bones, or food crusts on pottery from sites near rivers or lakes. The reservoir age in hardwater rivers can be up to several thousand years and may be highly variable. Accurate 14C dating of freshwater-based samples requires knowing the order of magnitude of the reservoir effect and its degree of variability. Measurements on modern riverine materials may not give a single reservoir age correction that can be applied to archaeological samples, but they show the order of magnitude and variability that can also be expected for the past. This knowledge will be applied to the dating of food crusts on pottery from the Mesolithic sites Kayhude at the Alster River and Schlamersdorf at the Trave River, both in Schleswig-Holstein, northern Germany.

Recently, several case studies have demonstrated the presence of human radiocarbon dietary reservoir effects in inland contexts. Freshwater reservoir effects present a high degree of variability, making it difficult to define local reservoir effect reference values necessary for correcting chronologies based on 14C dating of human bone material. Here, we investigate the hypothesis that 14C ages of edible freshwater species are delimited by the 14C ages of the main water carbon pools (DIC, POC, and DOC).

Water, plant, algae, bivalve, and fish samples were collected from lakes Schwerin and Ostorf (Germany). 14C and isotopic measurements were performed on the floral and faunal species and on water DIC, POC, and DOC. The results demonstrate the potential of the study area for large and variable freshwater reservoir effects. In the case of Lake Schwerin, the working hypothesis was verified as the 14C ages of faunal and floral species were delimited by the 14C ages of water DIC and POC, probably associated with 2 extreme categories of food chains (grazing and detritus). While the results obtained confirm the working hypothesis and suggest a relatively straightforward interpretation, further research is necessary to investigate possible spatial and seasonal variations.

The Ansanto Valley (southern Italy) is characterized by vents and boiling mud lakes that emit typical volcanic exhalations (mostly fossil CO2). This fossil dilution spreads over the Ansanto Valley and its impact on local trees is investigated in this study. Six trees at increasing distance from the emitting sources and 2 aliquots of gas were sampled. Dendrochronological analysis was performed on tree cores in order to check the accuracy of the tree-ring sequences; the results indicate no anomalies in the curves of the analyzed trees. δ13C and radiocarbon (14C) analyses were performed on the α-cellulose extracted from some selected tree rings. The main aim of δ13C analysis was to gain information about the origin of CO2 arising from the source; the results support the hypothesis of a carbonatic origin, with respect to a volcanic origin. 14C analysis was performed to evaluate the influence and to quantify the percentage of fossil dilution characterizing the local atmosphere and affecting the trees at different distances from the source during the years. The results show the presence of a strong fossil dilution affecting the trees, increasing toward the sources (from ∼6% at 80 m distance to ∼30% at 20 m from the nearest vent) with quite stable values over the examined period.

Research concerning the variability of the marine radiocarbon reservoir effect (ΔR) in the southern Iberian Atlantic coast confirms the existence of different ΔR values for regions that correspond to different oceanographic conditions. Due to these oceanographic conditions, the southern Iberian Atlantic coast can be divided into 3 zones: the Barlavento (windward), where the coastal waters are influenced by an intense upwelling of the northeastern Atlantic circulation (positive ΔR values); the Sotavento (leeward), where an upwelling area of minor intensity occurs; and the Andalusian coast, where because of its configuration does not present any wind-driven coastal upwelling (negative ΔR values). For the first time, ΔR values were determined for the Sotavento coastal region and, at the same time, new ΔR values were calculated for the Barlavento and the Andalusian coast for the last 3000 yr taking into account the data already obtained but now using a new methodology for calculation. In this way, ΔR weighted mean values were determined for the 3 regions of the southern Iberian Atlantic coast: ΔR = +69 ± 17 14C yr (Barlavento), ΔR = −26 ± 14 14C yr (Sotavento), and ΔR = −108 ± 31 14C yr (Andalusian coast). These values are in accordance with the different oceanographic conditions prevailing in these coastal regions. The data also allow identification of a Bond event at 0.8 ka cal BP and a drastic change in the oceanographic conditions in the Barlavento and Andalusian coastal areas during the 5th millennium cal BP.

We report results of duplicate measurements of dissolved organic carbon concentrations ([DOC] as μM) and Δ14C in seawater in order to assess the total uncertainty of reported [DOC] and Δ14C measurements via the UV oxidation method. In addition, pure International Atomic Energy Agency standards analyzed over a 4-yr period are evaluated. We find the total uncertainty of Δ14C measurements to be ±4.0. However, in samples that were thawed, subsampled, and refrozen prior to UV oxidation, the total uncertainty of Δ14C measurements is on the order of ±10. The [DOC] measurements of these samples were also higher by 1.8 ± 0.3 μM. The reason(s) for these documented increases in total [DOC] and Δ14C uncertainty are unclear. In order to minimize any effects on sample measurements, we recommend the following: 1) regular monitoring of duplicate samples, DOC standards, and diluent (Milli-Q™) water for Δ14C and [DOC] measurements; 2) thawing a sample immediately and only once prior to UV oxidation; 3) avoid the use of DOC-leachable plumbing (such as PVC pipe) in both water systems feeding and within Milli-Q systems; and 4) consider the use of DOC-free diluents (i.e. pre-UV oxidized Milli-Q or sample water).

Pollen extracted from ocean and wetland sediments cored from the eastern Canadian Margin, James Bay region, and Atlantic provinces of Canada have been radiocarbon dated and results are reported here. Pollen dates from ocean sediments were compared with marine carbonate (mollusk shells or foraminifera) dates from the same core levels, dates for which validity was assessed via correlations with other cores, and for which reworking has been excluded. Pollen samples from 3 tidal wetlands were taken from levels dated with 137Cs and 210Pb profiles. Pollen dates from 2 additional wetlands were compared with 14C dates of botanical macrofossils. Most pollen dates disagree with 14C dates based on macrofossils or carbonates, with age differences typically exceeding 250 yr and reaching 4000 yr in one instance. In some cores, pollen dates show age reversals. Significant proportions of reworked pollen grains in ocean and wetland samples are associated with pollen dates that are too old. Prolonged core storage could result in pollen 14C ages that are too young, possibly because of growth of fungi or other microbes, but more work is needed to verify this hypothesis. Despite the problems we encountered, some pollen dates are consistent with other 14C dates from the same core levels, suggesting this dating method can work, but at present, more work is needed to understand the conflicting results obtained.

Lacustrine stromatolites are layered accretionary structures formed in shallow water by cyanobacteria. They are a precise indicator of high lake limits and their morphology and structure provide an insight into paleoenvironments of the time. Previous research on lacustrine stromatolites from Etosha Pan in Namibia based on radiocarbon ages of carbonates were close to the limit of the method and did not account for any possible 14C reservoir effect. The ages were used to suggest that the basin was not extensively flooded during the last 40,000 yr. To assess the reservoir effect, the age characteristics of a stromatolite from Poacher's Point were investigated by 14C dating both carbonate and organic residue from samples at different depths in the deposit. The ∼15-cm-diameter stromatolite was separated into 12 zones from the center to the edge and block samples were cut from each zone; the carbonate and residual organic residue were dated separately. The carbonate ages ranged from 34,700 to 24,700 14C yr BP and the organic ages from 15,700 to 2500 14C yr BP. Ages generally increased with increasing distance from the surface of the deposit. We believe that the organic ages are an accurate estimate of the stromatolite's age, while the much older carbonate ages reflect incorporation of old carbon from limestone bedrock and ancient calcrete introduced by stream and spring flow. Excluding the 2 oldest organic ages (15,700 and 13,600 14C yr BP), which may reflect contamination by older organic material washed into the lake during flooding, a linear regression relationship between carbonate and organic ages indicates that the reservoir effect on carbonate ranges up to ∼24,000 14C yr BP but decreases slightly as the true age of the deposit increases. This regression relationship was used to correct 2 finite carbonate ages for stromatolites from Pelican Island obtained in the early 1980s, which together with our new organic age for a stromatolite from Andoni Bay, document a >8-m-deep lake in Etosha Pan during the Late Pleistocene, at and prior to ∼34,000–26,000 cal yr BP. The organic carbon ages from the Poacher's Point stromatolite suggest prolonged lacustrine conditions during the early to middle Holocene (8000–6600 cal yr BP) but not to the extent seen during the Late Pleistocene.

The Indonesian Arc represents the subduction of the Indian-Australian plate beneath Asia. It has been the scene of catastrophic tectonic activity, including the recent 2004 M=9.1 Aceh earthquake and resulting Indian Ocean tsunami. We have dated planktonic forams associated with historic tephras (Tambora, 1815 and Krakatau, 1883) in marine sediment cores to determine radiocarbon reservoir ages for 2 locations along the arc. Our best estimates for 19th century regional reservoir corrections (ΔR) are +90 ± 40 yr for surface-dwelling species and +220 ± 40 yr for mixed planktic assemblages containing some upper thermocline species, but scatter in the data suggests that past surface reservoir ages may have varied by about ±100 yr. We used the results of this study to investigate a proposed very large AD 535 eruption at or near Krakatau. We find no evidence for ash from such an eruption, and although this is negative evidence, we consider it sufficiently strong to rule out any possibility that one took place.

We used the radiocarbon wiggle-match dating technique to date the varved sediments of Lake Gyltigesjön in southern Sweden with the main aim to construct an accurate chronology covering the period between about 3000 and 2000 cal BP. Wiggle-match dating was applied to bulk sediments to evaluate the possibility of constructing accurate chronologies in the absence of terrestrial plant macrofossils and when the amount of old carbon in the sediments is unknown. Facilitated by a floating varve chronology and relatively stable 14C reservoir ages, the results show the possibility to assess the contribution of old carbon solely based on the 14C wiggle-matching of bulk sediments. We confirm the wiggle-matched chronology and the 14C reservoir age of approximately 260 yr by cross-checking the results with 14C dating of macrofossils. The obtained calibrated ages based on bulk sediments have an uncertainty range of about 60–65 yr (95.4% confidence interval). This study confirms that 14C wiggle-match dating of bulk sediments is a viable tool when constructing high-resolution chronologies. The method is especially useful in Sun-climate studies since the timing between solar activity variations (expressed as 14C variations) and climate changes can be accurately determined.

Luzia woman is considered one of the oldest Paleoindian skeletons found in the Americas. Luzia was found at the Lapa Vermelha IV site (Lagoa Santa, Minas Gerais, Brazil) in 1975 by the archaeologist Annette Laming-Emperaire (1917–1977) who sent to the Gif laboratory charcoals collected in the vicinity of the skeleton for radiocarbon dating. Twenty-nine charcoal samples were dated from different levels of the stratigraphy of the cave (Délibrias et al. 1986). Recently, new charcoal samples were discovered within Laming-Emperaire's correspondence and were subsequently dated by the Saclay AMS laboratory. The new results confirm the age of Luzia; however, the ages correspond to the younger part of the interval: charcoals found near Luzia's skull give an age of 10,030 ± 60 14C yr BP (11,243–11,710 cal BP).

The question of when the first humans arrived in the New World has been a bone of contention for several decades. Similarly, the age of rock paintings has been heatedly debated. Settlements in the Serra da Capivara National Park have been dated to between 5 kyr and >50 kyr, which is far older than the Clovis barrier. Moreover, calcite formation on a rock-wall painting in a rockshelter yielded thermoluminescence (TL) and electron paramagnetic resonance (EPR) ages older than 35 kyr BP (Watanabe et al. 2003). In an attempt to contribute to this ongoing debate, we have studied calcite deposits covering prehistoric paintings from several rockshelters (Toca da Bastiana, Toca do Serrote de Moendas, and Toca da Gameleirinha [Pedra pintada]). Coupled AMS (accelerator mass spectrometry) 14C and MC-ICPMS (multi-collector inductively coupled plasma mass spectrometry) 230Th/U dating was performed in Toca da Gameleirinha. The ages obtained for these cal-cites are younger than 12 kyr and suggest that the paintings could be more recent than proposed by previous studies.

Based on archaeological and radiometric constraints, previous studies have divided pre-Columbian times of Ecuador into a succession of cultural periods. The Paleoindian and Preceramic periods encompass the time from the first Amerindian occupation to about 4000 BC. The Formative period extends from ∼4000 to ∼300 BC, while the Regional Development (∼300 BC to ∼AD 700) and Integration periods predate the Columbian period, which starts in AD 1533 in Ecuador. The Formative cultural period is poorly known from earlier studies. Here, we bring the first documentation of Formative age occupation around Tungurahua Volcano, 120 km SW of Quito, and show that local settlements were devastated by a violent eruption around 1100 cal BC. Recent volcanological works combining lithostratigraphic, petrologic, and geochronologic analyses reveal that the steep-sloped Tungurahua edifice suffered a major Late Holocene flank failure. We show that the failure event resulted from a major explosive eruption triggered by massive magma intrusion inside the volcano. Decompression of the magma due to a flank collapse resulted in a violent, high-velocity directed blast explosion, which deposited charcoaland sherd-rich ash layers upon and near the volcano. Our 14C results range from 2225 ± 30 to 5195 ± 45 BP, but most cluster between 2640 ± 45 and 3195 ± 45 BP. A calibration analysis indicates that the event took place at ∼1100 cal BC, in the Formative period. We gathered 38 pottery sherds from 3 localities. The sherds show a diversity of size, shape, color, and ornamentation. Examination of pastes, surface finish, and firing indicates that our material shares many common features from site to site. The material from Tungurahua shares affinities with the Cotocollao tradition, which developed in the Quito region between 1500 and 500 BC, and with the Machalilla tradition (coastal region of Ecuador), with the occurrence of carinated bowls with punctuate decorations at 1500–1000 BC. Our study reveals that the ∼1100 cal BC Plinian eruption of Tungurahua Volcano is among the oldest known volcanic disasters in the Andes.

Sambaquis, famous Brazilian coastal shellmounds, represent a successful and long archaeological cultural tradition, with hundreds of sites spread over 2000 km of the Brazilian south-southeast coastline. These sites have many burials within a sequence of layers comprising a mix of faunal remains, charcoal, ashes, and sand, thus resulting in very complex stratigraphic structures. Several radiocarbon samples exhibit ages between 8000 and 1000 cal yr BP. In the Brazilian southeastern coastal hinterland, at the Ribeira de Iguape basin, 36 small mounds similar to the sambaquis were found, composed mostly of landsnail shells, bone remains of terrestrial fauna, lithic and osteodontological artifacts, and quite a few burials. Through the last decade an archaeological research project has accomplished extensive surveys and systematic 14C sampling, together with excavations in selected sites. A sequence of ages has been obtained from different samples (16 on shell, 10 on human bone, and 6 on charcoal) representing 19 sites. These dates range from 10,000 to 1000 cal yr BP, highlighting around 9000 yr of cultural continuity, contemporary to both the Paleoindian record over the hinterland plateau, and older than their coastal counterparts, the sambaquis. By presenting the 14C distribution and an overview of the archaeological features of these sites, we discuss briefly the dispersion and settlement processes of early peopling in this area of Brazil.

The archaeological site of Zaballa is a Medieval rural site located in the province of álava (Basque Country, northern Iberia). The site has been excavated during a rescue archaeology project, over an area of about 4.5 ha, where human occupation has been documented ranging from the 6th to 15th century. The archaeological operations have shown the transformation of the village, in diachronic terms, by unearthing the structure of production areas (agricultural lands, storage areas, and craft activities), the shape of domestic spaces, and the Saint Tirso monastery, with its adjacent cemetery. Much of the evidence and features related to a peasant community are small and disturbed by recent agricultural activities, and are therefore difficult to be interpreted in social terms. Studying dietary patterns has helped to fill this gap by providing a protein-rich diet of the elitist population and by highlighting the existence of hierarchies separating the inhabitants of Zaballa. In this paper, we discuss the reconstruction of the chronological sequence of the site inhabitation, with a multidisciplinary approach. The archaeological evidences and the critical use of radiocarbon dating have been integrated with stable isotope analysis on human remains found in the cemetery of the church of San Tirso, resulting in a first attempt to find evidence of the social structure of the rural community of Zaballa.

A Brandgrubengrab entails a specific way of depositing human remains whereby the cremated remains of the deceased and other remnants of the funeral pyre, such as charcoal and burnt objects, are jointly deposited onto the bottom of a pit. This type of burial became increasingly popular during the Late Iron Age and the Roman period, when it was the main basic funerary structure used in western Flanders. In recent years, more attention has been paid to establishing a more precise chronology for these funerary structures by applying radiocarbon dating. A set of 40 14C dates obtained from samples originating from small cemeteries and isolated cremations now offers new insights in the development of this specific cremation burial ritual.

Grotta della Monaca is a karstic cave in Calabria (southern Italy) that plays an important role in reconstructing the oldest strategies for the acquisition of mineral resources in the Mediterranean. In fact, systematic archaeological excavations carried out by the University of Bari allowed the identification of intense prehistoric mining activities aimed at the exploitation of iron and copper ores. Archaeological evidence suggests different phases of frequentation of the cave spanning from the Upper Paleolithic, Neolithic, Copper and Bronze ages up to the Middle Ages. In order to establish an absolute timeframe for the different phases, a radiocarbon dating campaign was carried out and the results presented in this paper.

The Bronze Age site of ķivutkalns with its massive amount of archaeological artifacts and human remains is considered the largest bronze-working center in Latvia. The site is a unique combination of cemetery and hillfort believed to be built on top of each other. This work presents new radiocarbon dates on human and animal bone collagen that somewhat challenge this interpretation. Based on analyses using a Bayesian modeling framework, the present data suggest overlapping calendar year distributions for the contexts within the 1st millennium BC. The carbon and nitrogen isotopic ratios indicate mainly terrestrial dietary habits of studied individuals and nuclear family remains buried in one of the graves. The older charcoal data may be subject to the old-wood effect and the results are partly limited by the limited amount of data and the 14C calibration curve plateau of the 1st millennium BC. Therefore, the ultimate conclusions on contemporaneity of the cemetery and hillfort need to wait for further analyses on the massive amounts of bone material.

The era of early urbanization in Finland coincides with large variations in the atmospheric radiocarbon concentration around the 13th–14th centuries AD. Therefore, the uncertainties of an individual 14C date are too large to support studies of this time period effectively. In this work, we have employ tree-ring wiggle-matching methodology and used Bayesian modeling of dates to account for stratigraphical a priori information within Aboa Vetus Museum, Turku, Finland. The wiggle-match method helps significantly to overcome the calibration-curve-induced challenges within 14C dating. The results of the dating model agree with the typological dates of the archaeological finds and illustrate a gradual evolution of urbanization in one of the oldest cities in Finland.

A suite of accelerator mass spectrometry (AMS) radiocarbon dates for the Ufa-II archaeological site in Bashkortostan, Russia, is obtained for the first time. Dating was done on charcoal samples from a sequence of cultural deposits collected during the 2011 digging season. An age-depth chronology is established using the Bayesian deposition General Outlier P_Sequence model. The oldest age for the site at the horizon immediately over the sterile ground was cal AD 137–237 (68% probability), corresponding to the beginning of site occupation. The youngest 14C date found was late 6th to early 7th century cal AD for the extensive planked boardwalks unearthed at the site. The 14C dates are in good agreement with archaeological determinations based on discovered artifacts.

We studied the chronology and periodization of the Pit-Grave (Yamnaya) culture at the Volga and Ural interfluve. Establishing the chronology of the Pit-Grave culture by archaeological methods is difficult due to the lack of artifacts in the burials. Therefore, we excavated 3 kurgan groups in the Orenburg region of Russia during the last decade. Eighteen kurgans of the Pit-Grave culture were studied using archaeological and paleopedological methods and radiocarbon dating. The funeral complexes studied were divided into 3 stages. A variety of carbon-containing materials from the same complexes were dated by different laboratories to increase the accuracy of the obtained dates. In addition, from the excavations of the last years some monuments of the Repino stage, the earliest period of the Pit-Grave culture, were dated using ceramics. Together with archaeological and paleopedological data, 14C dating helped to clarify and, in general, to confirm the 3-stage periodization of the Pit-Grave culture in the Volga-Ural interfluve: the early (Repino) stage, 4000–3300 BC; the advanced (classical) stage, 3300–2600 BC, which is divided into substages A and B at 3300–2900 and 2900–2600 BC, respectively; and the late (Poltavkinsky) stage, 2600–2300 BC.