We investigated age estimation of persons using 45 Japanese human teeth that consisted of mainly the third molar. We measured the radiocarbon content in tooth enamel hydroxyapatite from the crown as well as those in collagen and bioapatite in the root of the same tooth. Age estimations from tooth enamel apatite yielded an absolute age shift of 1.7±1.4 yr from the true age. This value suggests that estimating the age of Japanese people from tooth enamel is as accurate as the previous studies conducted in Europe and the USA. The 14C analysis of roots suggested that bioapatite is formed slightly later than collagen in the same tooth roots. The appropriate formation age ranges suggested by the tooth enamel analysis can be optimized and confirmed by using the additional F14C values of the root samples. We also noticed a characteristic trend of enamel δ13C values in comparison with the formation ages of the crowns of the teeth. The δ13C value tends to increase gradually from –13.0‰ to –11.5‰ from the 1960s to the 1970s, probably being caused by changes in the Japanese diet. This trend may support the selection of proper tooth formation age as supplemental data in addition to 14C content analyses.

The measurements reported in this list were made in theLouvain C14 dating laboratory in 1966.Sample preparation, counting procedure andcalculation method are described in the previouslists. Ages are calculated on the basis of aC14 half life of 5570 yr (Godwin,1962). Errors, including the experimental standarddeviation of the counting rate of the background, ofthe modern standard and of the unknown sample, areexpressed by 1σ (Crèvecoeur and others, 1959).

A simple procedure for the conversion of 14C NBS oxalic acid standard to benzene without direct combustion or wet oxidation is reported. Fractionation in the synthesized benzene was not detected.

We have studied the isotopic composition of recently precipitated travertines to determine the initial 14C activity of ancient travertine deposits. We found that the 14C activity of recent travertines of northeastern Spain was a function of the distance from the spring, resulting in variations in the initial 14C activity of the ancient travertine formations. We calculated the ancient travertine radiocarbon ages by using the ratio between the 14C activity of recent travertines and that of present atmospheric CO2 as the initial 14C activity.

This date list reports samples completed before 1979. Methods, equipment, and techniques were reported previously (R, 1968, v 10, p 246; R, 1970, v 12, p 87). Age calculations are based on the conventional 14C half-life of 5568 years. The working laboratory standard is 95% of the NBS oxalic acid standard (SRM 4990). Results are reported in years before 1950 and the standard deviation is based on counting statistics of sample, background, and modern standard. Corrections for δ13C are not included.

The following list includes a selected number of measurements made during 1967-1968 in the Natural Radiocarbon Laboratory of the Centre de Recherches Radiogéologiques de Nancy. This list is a continuation of Nancy Natural Radiocarbon Measurements I (Radiocarbon, 1968, v. 10, p. 119-123). The dating method, counting technique, and equipment are described in that list. All measurements were made in a proportional counter with a capacity of 1.16 L, normally filled with CO2 under a pressure of 736 mm Hg. Ages are calculated using a C14 half-life of 5568 yrs with 1950 as reference yr. Modern standard used following samples Ny-118 is 95% of NBS oxalic acid activity. The SC14 mentioned later in the date list are calculated according to Broecker and Olson (1959).

A series of recent papers has called for multiple radiocarbon dates on planktic foraminifera to assess stratigraphic continuity in deep-sea sediment cores. This recommendation comes from observations of anomalous 14C dates in planktic foraminifera from the same stratigraphic level. Potential reasons include bioturbation, downslope transport, secondary calcification, carbonate dissolution, and differential preservation. In this study, paired 14C dates on dissolution-susceptible Globigerinoides ruber and dissolution-resistant Neogloboquadrina dutertrei are used to evaluate a Gulf of Mexico sediment core. Fourteen of 15 pairs (between 8815 and 12,995 uncorrected 14C yr BP) yield concordant uncorrected 14C ages (mean difference −2 ± 75 yr), attesting to continuous deposition at high accumulation rates (>35 cm/kyr). For 1 pair, N. dutertrei is nearly 1000 yr younger, which is difficult to explain by any combination of dissolution and bioturbation or downslope transport, given the excellent carbonate preservation and persistent laminations. The concordant ages underscore the utility of paired 14C dates in planktic foraminifera as a means of assessing stratigraphic continuity in deep-sea sediment sequences.

In this study, we aim to characterize the main processes controlling 14CDIC concentrations in porewater at the shallow shelf (water depth less than 120 m) off the Mediterranean coast of Israel. At these water depths, we expected to find evidence for seawater penetration toward the coast, since this area was flooded by seawater only some 18,000 yr ago (the end of the Last Glacial period).

Measurements of the chemical composition (14CDIC) and stable carbon isotopic composition (δ13CDIC) were performed in several sediment cores (40–250 cm long) at water depths between 6 and 115 m. At water depths of 60 m, represented by a 2.5-m-long sediment core, the porewater 14CDIC levels (85–87 pMC) were lower than the corresponding sediment values in each layer (92–95 pMC), mainly due to the oxidation of relatively old organic matter (about 70 pMC) with no evidence to advection. In contrast, sediment cores from water depths shallower than 50 m showed only slight anaerobic oxidation and high 14CDIC values of approximately 100 pMC, indicating possible downward advection. These geochemical observations support the perception that the penetration of seawater into the coastal aquifer occurs at the shallow water zone (<50 m), while further verification by deeper cores is required.

This list includes ages measured from August 1974 to May 1976 using the benzene scintillation method. All archaeologic and geologic samples except Sahara Libico series, come from Italian territory. These datings were carried out partly with the liquid scintillation counter previously described (Alessio et al, 1973) and partly with a new liquid scintillation counter (Alessio et al, 1976b). Vials, 4.5ml in volume, described in Alessio et al, 1973. Mixture consists of 3.5ml of benzene from sample and 1ml of commercial liquid scintillator NE 216. The characteristics of new counter are: background 2.90 cpm and figure of merit

A study of water and carbon isotopes was conducted in a bare plot in the unsaturated zone of the Yatir Forest in the northern Negev of Israel. Sediment cores were collected in three different seasons. Measurements include profiles of mineralogy, moisture and its δ18O and tritium content, dissolved inorganic carbon (DIC) and its δ13C (‰) and Δ14C (‰) content, and δ13C (‰) and Δ14C (‰) in the solid sediment. The profiles of moisture and δ18O in the cores show clearly the effect of evaporation. The tritium profile indicates infiltration of water (0.11 m yr−1). The source of carbon in the DIC is CO2 released by biotic activity through roots of trees and of seasonal plants, which show seasonal variations, and by decay of organic debris. The δ13C (‰) profiles show clearly the chemical transition from dissolved CO2 (δ13C = −22‰) to bicarbonate (δ13C = −14‰). At greater depth (–11.3‰), the δ13C becomes similar to the δ13C in the aquifer below (–12.5‰). The effect of secondary processes is evident in the profile of Δ14C in the DIC. It shows a clear decrease with depth due to exchange with the sediment at a rate of 10‰ yr−1. Precipitation of carbon from the DIC on the sediment is 1.1 mg C Lsed−1 yr−1, negligible compared to the 28 g C in 1 Lsed. In the solid sediment, there is a gradient in Δ14Ccarb at the top meter. The net precipitation of 14C from the DIC on the sediment (0.25 to 1.1‰ yr−1), corrected for decay, cannot be observed in the deeper sediment. The presence of 14C in the top 1 m of the sediment is explained by two possible processes: accumulation of 14C-tagged dust (∼0.05 mm yr−1) and/or long-term cumulative precipitation from the DIC.

There are hundreds of preserved medieval buildings in the mountainous part of Ingushetia, including Christian churches, crypts, temples, sanctuaries, battle towers, and living buildings. The chronology of their construction period is still questioned, as there are no radiocarbon (14C) dates published for these buildings and their dating is mainly based on architectural features, a few historical sources, and sometimes on accompanying archaeological material. The aim of this study is to assess more precisely the period of their construction. To do this, we selected the 10 most prominent medieval buildings that contain wooden construction elements and sampled these wooden elements in order to apply 14C accelerator mass-spectrometry dating (AMS) followed by wiggle-matching. From two of these buildings, plaster and mortar were also sampled for 14C AMS dating. This is the first time that these kinds of analyses have been performed for medieval buildings from the mountainous part of Ingushetia. For 6 out of 10 buildings, we acquired sufficiently precise dates that helped us to clarify their construction period. For the other 4 buildings, the acquired dates are still informative but could be refined further with additional 14C analyses. The calibrated dates obtained cover the period from AD 662 until recent time with the majority of them concentrated in 15th–17th centuries.

Given the nature of medieval artifacts and resulting research requirements, a precise temporal classification is essential. It is especially important for the purposes of medieval archaeology in interpreting archaeological finds/finding situations and identifying them with a historical events or figures, for example, to identify skeletal remains of a known historical figure or to establish a chronological sequence of various cultural and architectural changes within an area. Due to the fact that the uncertainties of radiocarbon (14C) analyses have been decreasing in recent years, the applicability of 14C dating for such purposes is now growing. In this work, we aim to demonstrate the current possibilities of the use of AMS 14C analyses on specific cases and confront the results with other available data. 14C data from skeletal remains of members of the oldest Czech ruling dynasty of the Přemyslids (about 880–1306 AD) were obtained in recent years. Archaeological research conducted in the three oldest churches in the Prague Castle discovered skeletal remains of three members of the second, two members of the fourth and two members of the fifth generation. This case study of the application of 14C data has three parts: i) identification of excavated individuals; ii) demonstration of the application using current AMS-based analysis of 14C on medieval osteological material and tests of our preparation method; iii) contributing to discussion and consulting with other problematical 14C age alteration influenced by diet, age of bone collagen or seasonal variation of 14C activity. The obtained results and the issues arising from them clearly highlight the necessity of a multidisciplinary cooperation in this type of study.

During the period from 1995 to 2011, radiocarbon measurements from the coast around Hartlepool in NE England have revealed anomalous enrichments in seawater, sediment, and marine biota. These cannot be explained on the basis of atomic weapons testing or authorized nuclear industry discharges, including those from the nearby advanced gas-cooled reactor. Enhanced 14C-specific activities have also been observed since 2005 in biota during routine monitoring at Hartlepool by the Food Standards Agency, but are reported as “likely” originating from a “nearby non-nuclear source.” Studies undertaken in Hartlepool and Teesmouth during 2005 and 2011 suggest that the 14C discharges are in the vicinity of Greatham Creek, with activity levels in biota analogous to those measured at Sellafield, which discharges TBq activities of 14C per annum. However, if the discharges are into Greatham Creek or even the River Tees, it is proposed that they would be much smaller than those at Sellafield and the high specific activities would be due to much smaller dilution factors. The discharge form of the 14C remains unclear. The activity patterns in biota are similar to those at Sellafield, suggesting that initial inputs are dissolved inorganic carbon (DI14C). However, the mussel/seaweed ratios are more akin to those found around Amersham International, Cardiff, which is known to discharge 14C in an organic form. 14C analysis of a sediment core from Seal Sands demonstrated excess 14C to the base of the core (43–44 cm). 210Pb dating of the core (0–32 cm) produced an accumulation rate of 0.7 g cm−2 yr−1, implying that 14C discharges have occurred from the 1960s until the present day.

The question of whether the rise in CO2 levels observed during the industrial era has influenced the rates of tree biomass growth represents one of the main unsolved questions in the field of climate change science. In this framework, the African tropical forest represents one of the most important carbon (C) sinks, but detailed knowledge of its response to elevated CO2 is still lacking, especially regarding tree growth rate estimations. A major limitation to determining growth rates in the African tropical region is that many trees lack seasonality in cambial activity determining annual growth rings. In this study, several species of trees characterizing the African tropical forest have been investigated to estimate their biomass growth rate by means of a procedure based on 14C and growth models. A total of 71 subsamples were analyzed for a Entandrophragma cylindricum (sapele) tree, and 38 and 25 wood subsamples for Erythrophleum suaveolens (tali) and Triplochiton scleroxylon (ayous) trees, respectively, using radiocarbon measurements at the Centre for Isotopic Research on Cultural and Environmental Heritage (CIRCE). All measured modern samples were in agreement with the Southern Hemisphere (SH) 14C bomb-spike curve. Observed preliminary results indicate a decrease in the growth rate of the sapele tree (∼350 yr old) in the industrial period compared to the pre-industrial era. Growth rates for trees of the other 2 species were higher than sapele, with ayous being the fastest-growing species.

For at least 100,000 yr, marine shell beads have been important ornamental and symbolic artifacts intimately associated with the behavior of anatomically modern humans. In California, giant rock scallop (Hinnites multirugosus) beads were once thought to have been used only for the last 1000 yr, where they were considered to be markers of high social status among the Chumash Indians of the Santa Barbara Channel region. Direct accelerator mass spectrometry (AMS) radiocarbon dating of 1 giant rock scallop ornament and 2 beads from San Miguel Island extends the use of this shell for personal adornment to at least 8000 cal BP. Our study emphasizes the importance of direct AMS 14C dating of artifacts to enhance cultural chronologies and clarify the antiquity of various technologies and associated behaviors. Our results also caution archaeologists when equating artifact rarity with sociopolitical complexity.

Karst environments preserve some of the best archives of past climate, vegetation, hydrology, anthropogenic impact, and landscape evolution providing that a reliable chronology can be established. Here we present an example of the system of the Plitvice Lakes (Dinaric karst, Croatia), which is characterized by intensive tufa and lake sediment formations. The radiocarbon dating method, combined with some other dating methods and various geochemical and isotope analyses, showed that the Plitvice Lakes system in the present form has existed for about 8000 years. Older tufa deposits were dated to warm interglacial periods. A long-term comprehensive multi-proxy study showed that all environmental compartments (atmosphere, various water bodies, soil, bedrock, DIC, terrestrial and aquatic biota, and of course various secondary carbonates) must be included in order to obtain trustworthy results.

We present results that demonstrate the potential of the Packard Tri-Carb® Model 2770TR/SL for radiocarbon dating. For 2 g of sample benzene, a stable background count rate of 0.307 cpm and a stable counting efficiency of 64.78% were determined using a 13–75 keV counting window. Changes to the mathematical routines for t-SIE (quench indicating parameter) calculation and a reduction in the activity of the external standard have enabled stability of the t-SIE to be achieved, and combined with the use of a suitable balance point counting window; all of these factors give the stability of performance required for 14C dating. Calculations based on the above parameters indicate that the limit of detection for 2 g samples, counted for 5000 min, is >48,900 yr bp. The great advantage of this system is that these data were acquired using inexpensive standard 7-mL low potassium borosilicate glass vials. Vial holders manufactured from BGO reduced the background to 0.15 cpm with a minimum effect on efficiency (64.46% for 13–75 keV). A similar calculation of the limit of detection gave >51,700 bp. The use of the BGO vial holders in other instruments employing time-resolved liquid scintillation counting (TR-LSC) (Models 2250CA and 2260XL) also brought about significant improvements in detection limits.

Radiocarbon (14C) ages were determined for 10 iron samples from the war booty offering site in the Nydam peat bog (SE Denmark), and compared to archaeologically inferred periods of deposition. Additional 14C measurements were carried out for modern iron standards made with charcoal of known isotopic composition to evaluate possible effects of handling. Modern iron standards give depleted 14C concentrations, compared to the initial charcoal 14C composition, and may indicate carbon fractionation effects during carbon dissolution in the iron lattice. Further studies are needed to verify if this is a common effect during iron production. 14C dating of two swords and one ax head are in comparatively good agreement with expected deposition times and indicate only small old-wood effects. In contrast, 14C dating of iron rivets from the Nydam (B) oak boat proved difficult due to corrosion with siderite (FeCO3) and conservation with wax. A step-combustion procedure was applied, using a low (∼570–600°C) temperature prior to the high (∼970–1000°C) combustion temperature for carbon extraction, aiming to remove siderite and wax before collecting the original carbon dissolved in the iron lattice. Nevertheless, measured 14C ages of the iron rivets differ by about 200–300 years from the dendro-date of the Nydam (B) oak boat they belong to, indicating persisting aging effects (e.g. old-wood, contamination with fossil carbon added during iron making and/or handling prior 14C dating). Also, a possible recycling of older iron cannot be excluded.

We have worked in collaboration with the Westinghouse Savannah River Company and Packard Instrument Company to develop a prototype instrument for remote, near real-time, in situ analysis of environmental levels of tritium in surface and ground water samples. The unit consists of a Packard Radiomatic™ 525TR liquid scintillation counter that has been modified to achieve lower detection levels through background reduction using Packard's After-Pulse Burst Discrimination electronics and an auxiliary Bi4Ge3O12 scintillation detector guard. The system is fully programmable to enable remote calibration, sample collection, sample analysis, reconfiguration of operational mode and interrogation for analytical results.