The dates given have been obtained during the year 1959. They have been made with carbon dioxide at 2 atmospheres pressure in a proportional gas-counter, as for the series given in Radiocarbon Supplement, volume 1.

We have reconstructed the initial activity of calcareous sediments by 1) measuring the 14C activity of recent pre-bomb-test calcareous deposits, 2) calculating the ratio of the 14C activity of the calcareous sediment to that of the adjacent coeval wood, and 3) extrapolating 14C activity of the deep lacustrine sediment layers to the surface, assuming a constant sedimentation rate. We show here that the uppermost sediment is affected by the global increase of atmospheric 14C activity due to thermonuclear bomb tests in the early 1960s. 14C activity of submerged aquatic plants showed values similar to 14C activity of DIC. Thus, organic residue of the sediment cannot be used for reliable 14C dating because of the unknown fraction of aquatic plant detritus. The initial activity, A0, obtained in a case study of the geochronology of carbonates in the Plitvice Lakes area, ranged from 70.5 to 72.2 pMC for Lake Prošće sediment, and from 75.9 to 76.7 pMC for Lake Kozjak sediment. These values also agree with calculated values based on the downstream increase of 14C activity of DIC in freshwater open to the atmosphere.

Measurement of 14C in samples of wood of precisely known age have shown that the cosmogenic 14C content of the CO2 in the atmosphere has not remained constant during the period of time covered by radiocarbon dating. As the terrestrial atmosphere mixes with a time constant of less than 3 years, these variations must be essentially independent of geographic location. The 14C in atmospheric CO2 must be a quantity that, at a given time, pertains to the terrestrial atmosphere as a whole. Not only is its knowledge necessary for deriving accurate radiocarbon dates, but it is also valuable in connection with many geophysical and astrophysical problems. Unfortunately, progress in our knowledge of 14C variations in the terrestrial atmosphere has been delayed by hidden experimental errors in results obtained by many laboratories. By rigorous statistical analysis of the La Jolla results, it is now possible to show that the 14C variations are not simple random fluctuations but show distinct regularities. Similar patterns of variations have been found in the growth rate of trees during the last 5000 years. Measurements of radiogenic 10Be currently being done by European workers promise to conclusively elucidate the 14C findings.

Bomb 14C has been used as a tracer for CO2 in ocean surface water to study CO2 exchange between atmosphere and ocean. Using ordinary cargo ships for sampling, we have been able to cover some parts of the Atlantic, Pacific, and Indian Oceans for certain periods. A total number of 520 samples from 89 locations were measured during the last 15 years. The data are presented both in tables and graphs. A maximum 14C concentration (Δ14C) of ca 20% was observed in temperate northern latitudes, and a few per cent lower at southern latitudes. A seasonal trend in the 14C variation, with summer maximum and winter minimum, was observed both in downwelling and upwelling areas.

Most of the 14C measurements reported here were made between October 1975 and October 1976. Equipment, measurement, and treatment of samples are the same as reported previously (R, 1968, v 10, p 36-37; 1976, v 18, p 290).

The use of accelerator mass spectrometry (AMS) for age determinations of paintings is growing due to decreasing sample size requirements. However, as only the support material is usually dated, the validity of the results may be questioned. This work describes a novel sampling and preparation technique for dating the natural organic binder using radiocarbon (14C) AMS. In the particular case of oil paintings, the natural oil used has a high probability of being representative of the time of creation, hereby circumventing the problem of the originality of the support material. A multi-technique approach was developed for a detailed characterization of all paint components to identify the binder type as well as pigments and additives present in the sample. The technique was showcased on a painting of the 20th century. The results by 14C AMS dating show that both the canvas and binding medium predate the signed date by 4–5 yr. This could be the time span for keeping painting material in the atelier. The method developed provides, especially given the low amounts of material needed for analysis, a superior precision and accuracy in dating and has potential to become a standard method for oil painting dating.

Carbon isotopes are widely used as indicators in the study of atmospheric CO2 variability in space and time. Preliminary results are part of a project investigating 13C and 14C concentration changes during the last 150 yr in Poland, both in industrial and ecologically clean regions, using annual tree rings (Pinus sylvestris, Populus nigra). The results describe the local Suess effect recorded in the industrial Kraków and Upper Silesia regions compared to changes of background radiocarbon concentration caused by global human activity in a “clean region,” Augustów Wilderness. The δ13C record also shows the influence of the local Suess effect.

Compound-specific radiocarbon (14C) dating often requires working with small samples of < 100 µg carbon (µgC). This makes the radiocarbon dates of biomarker compounds very sensitive to biases caused by extraneous carbon of unknown composition, a procedural blank, which is introduced to the samples during the steps necessary to prepare a sample for radiocarbon analysis by accelerator mass spectrometry (i.e., isolating single compounds from a heterogeneous mixture, combustion, gas purification and graphitization). Reporting accurate radiocarbon dates thus requires a correction for the procedural blank. We present our approach to assess the fraction modern carbon (F14C) and the mass of the procedural blanks introduced during the preparation procedures of lipid biomarkers (i.e. n-alkanoic acids) and lignin phenols. We isolated differently sized aliquots (6–151 µgC) of n-alkanoic acids and lignin phenols obtained from standard materials with known F14C values. Each compound class was extracted from two standard materials (one fossil, one modern) and purified using the same procedures as for natural samples of unknown F14C. There is an inverse linear relationship between the measured F14C values of the processed aliquots and their mass, which suggests constant contamination during processing of individual samples. We use Bayesian methods to fit linear regression lines between F14C and 1/mass for the fossil and modern standards. The intersection points of these lines are used to infer F14Cblank and mblank and their associated uncertainties. We estimate 4.88 ± 0.69 μgC of procedural blank with F14C of 0.714 ± 0.077 for n-alkanoic acids, and 0.90 ± 0.23 μgC of procedural blank with F14C of 0.813 ± 0.155 for lignin phenols. These F14Cblank and mblank can be used to correct AMS results of lipid and lignin samples by isotopic mass balance. This method may serve as a standardized procedure for blank assessment in small-scale radiocarbon analysis.

This date list covers most of the datings done during the period January 1960 to December 1961.

In Siberia, the accumulation of radiocarbon dates from archaeological sites since the 1960s makes it possible to compile a general Paleolithic 14C database, which contains about 440 entries as of late 2005. With these data, we can reveal the main chronological patterns of Paleolithic complexes, with a focus on the late Middle Paleolithic (Mousterian) and Upper Paleolithic. The 14C dates for late Middle Paleolithic industries in Siberia are quite “young,” up to about 30,000–28,500 BP and perhaps ∼27,000 BP. The emergence of the Upper Paleolithic in Siberia took place relatively early compared with Eastern Europe. At about 43,000–35,000 BP, blade-dominated industries existed in the Altai Mountains and Lake Baikal region, and numerous adornments are known from several sites of that age. The late Upper Paleolithic complexes with microblade technology from the Altai Mountains are 14C dated to about 35,000–28,000 BP, and represent the earliest unequivocal evidence of microblade manufacture in northern Eurasia. The end of the Paleolithic in Siberia is related to the appearance of pottery, which indicates the beginning of the Neolithic period. In northern Transbaikal, the earliest pottery complexes are dated to about 12,000–11,000 BP and in the Russian Far East even to ∼13,000 BP, while in most of Siberia they date to approximately 8000–6000 BP. The most important features of the Siberian Paleolithic chronology are: a) the long persistence of Middle Paleolithic complexes, until about 30,000–27,000 BP; b) very early Middle to Upper Paleolithic transition, ∼43,000 BP, closely connected with the emergence of art and symbolic behavior in the earliest Upper Paleolithic at this time; c) the very early origin of microblade complexes, at least at about 35,000 BP; and d) a gradual Paleolithic–Neolithic transition, beginning in the Russian Far East at ∼13,000 BP and in Transbaikal about 12,000–11,000 BP, in most of Siberia at about 8000–6000 BP, and even later in some northern regions.

The following list consists of dates for archaeologic and geologic samples mostly measured over the period from January 1980 to June 1981. The dates were obtained by liquid scintillation counting of benzene using the laboratory procedures outlined in previous lists (see, eg, BM VIII, R, 1976, v 18, p 16).

Radiocarbon dating is widely used when studying recent volcanic activity in the Kamchatka Peninsula due to the abundance of organic matter that is associated with the volcanic deposits. Here, we present the results of 14C dating of major volcanic events within the active South Kamchatka volcanic zone. South Kamchatka includes 8 recently active volcanic centers (stratovolcanoes, calderas, and large craters) that have been erupting during the Holocene. Their tephras represent useful markers for both the southern part of the peninsula and the Northern Kurile Islands. Since these marker tephra layers facilitate stratigraphic and tephrochronological studies in this area, it was important to determine their ages. We have obtained 73 new individual 14C dates on paleosol, peat, charcoal, and wood associated with the marker tephra layers, then complemented these data with 37 earlier published dates and analyzed the resulting data set. We selected the reliable dates and then obtained average 14C ages of marker tephra layers. The details of these procedures, as well as brief descriptions of South Kamchatka Holocene eruptions and their tephra beds, are presented in the paper.

This paper reports the results from applying the Cryo2SoniC (Cryobreaking, Sonication, Centrifugation) protocol to some lime mortars sampled from the citadel of Shayzar (Syria). The overall aims of this project are 1) to use the properties offered by high-precision accelerator mass spectrometry (AMS) radiocarbon dating for the evaluation of absolute chronology with its typical robust time constraints (i.e. 25 14C yr), and 2) to apply the dating directly to the citadel structures in order to prevent possible biasing effects potentially affecting indirect 14C dating on organic materials found at the study site. The analyses presented in this paper have been mainly performed as a preliminary check of the Cryo2SoniC methodology in order to assess its applicability to this study site by comparing observed mortar results with archaeological expectations about the citadel development phasing and charcoals found encased in mortars. Petrographic and mineralogical thin-section analyses by optical microscopy (TSOM), X-ray powder diffraction (XRD), and scanning electron microscopy plus energy dispersive spectroscopy (SEM/EDS) investigations were carried out for characterization of the mortar samples to verify the occurrence of some features, related to their production technology, which may introduce dating offsets. The resulting 14C calibrated ages were in agreement with the archaeological expectations based on type and stratigraphic site reconstructions, in situ inscriptions, and written sources. Such results showed also a general (with 1 exception) statistical agreement among the charcoals and the analyzed mortars simultaneously, confirming the archaeological expectations for the Shayzar citadel. Results presented in this paper indicate good accuracy for the applied procedure for chronology reconstruction and highlight the capability of Cryo2SoniC to further characterize the Shayzar site.

With one exception, the radiocarbon dates in this list were reported previously by Rainey and Ralph (1959). For discussions of the reliability of the dates, of the materials dated, and of the correspondence of the dates with estimated arctic chronologies, the reader is urged to refer to the original publication. The radiocarbon determinations were made over a period of several years. Those processed before 1956 were dated by the solid-carbon method and are so labeled; others, by the carbon-dioxide method. The age calculations are based on the average of several samples dated archaeologically and by tree-rings, corrected to zero age (Rainey and Ralph, 1959, p. 365). By this means the errors due to atmospheric depletion (Suess effect) and to past changes in radiocarbon concentration (de Vries, 1958; Willis, Tauber, and Münnich, 1960) have been minimized. The b.p. dates are calculated from A.D. 1957 (solid-carbon) and A.D. 1958 (carbon dioxide).

Continuous 14C data of 1 or 2 weekly samples of atmospheric CO2 are presented, collected near two nuclear power plants (NPP-Biblis and NPP-Philippsburg) located in the rather densely populated upper Rhine valley. Tree-leaf and tree-ring samples from the area of a boiling water reactor in northern Germany (NPP-Würgassen) are also presented and discussed. Additional atmospheric 14CO2 samples from two continental ‘clean-air’ stations in Germany and Austria were used as reference for the polluted areas. For January 1982, these samples yield a ‘clean-air’ 14C concentration in central Europe of Δ14C=255±5‰ (7.7pCi/gC = 1.45pCi/m3 air).

Correcting the 14C age of a sample for fractionation is straightforward if the measured carbon was derived entirely from the atmosphere, either directly or through chemical and/or biological reactions that originated with atmospheric carbon. This correction is complicated in the case of gastropods that incorporate carbon from limestone or secondary carbonate (e.g. soil carbonate) during shell formation. The carbon isotopic composition of such gastropod shells is determined by fractionation, as well as mixing of carbon from sources with different isotopic values. Only the component of shell carbonate derived from atmospheric carbon should be corrected for fractionation. In this paper, the author derives a new expression for correcting the measured 14C activity of gastropod shells for fractionation, and describe an iterative approach that allows the corrected 14C activity and the fraction of shell carbonate derived from atmospheric carbon to be determined simultaneously.

The following list consists of dates of archaeological samples, obtained by gas-proportional counting of ethane, between 1985 and the end of 1991. During this time a close cooperation has been established with the Israel Antiquities Authority, which now has an archaeologist (D.S.) participating in the operation of the lab and serving as a liaison officer with the archaeological community.

Sherds can be dated by four independent methods: 14C beta counting on associated material, accelerator mass spectrometry on carbon traces on and within the sherd, thermoluminescence studies on minerals within the sherd, and stylistic form. Age analyses of materials and sherds from several sites are shown in this work. Each technique has its own frequently encountered non-laboratory sources of error. A combination of at least two independent techniques is indispensable for the highest level of confidence.

Human and animal bone collagen from different Steppe Bronze Age cultures, including the Yamnaya, East Manych Catacomb, and Lola cultures, show large variations in δ13C and δ15N values. More positive values of δ13C and δ15N are caused by change in diet and/or a more arid climate. Human bones show reservoir effects caused by aquatic diet components. These effects can be quantified by paired dating of human bone and associated terrestrial samples. Previous research showed reservoir corrections for several cultures of the Eurasian steppes Bronze Age, leading to a revision of the local chronologies. Additional investigations showed that some paired dates do not reveal reservoir effects. Recently, our database was extended significantly with new 13C, l5N, and 14C analyses of the Lola, Krivaya, and Babino cultures. The size of the reservoir offset for the studied cultures is discussed.

Owing to the large basin area of the Caspian Sea, fluctuations in its level reflect climatic changes in the northern hemisphere. To reconstruct these fluctuations, I collected mollusk shells, plant debris, carbonates and organic matter samples for 14C dating from deposits of ancient salt marshes, depressions and bars formed during significant sea-level decline. I studied the impact of eolian sedimentation via parallel dating of carbonates and other materials. The data demonstrate that sea level rises during periods of cooling and falls during warming periods; this is true for both long-term (2–2.5 ka) and short-term climatic changes.