Radiocarbon dating of historical and archaeological wood can be complicated, sometimes involving issues of “inbuilt” age in slow-growing woods, and/or the possibility of reuse or long delays between felling and use of the wood. Terminus dates can be provided by dating the sapwood, or the outermost edge of heartwood, while a date from the pith can give an indication of the first years of growth. A sequence of samples from specific points within the bole can be used to determine the growth rate of the tree. Such a combined dating strategy is particularly useful in cross-referencing dates from a single piece, better placing it in its chronological context. This paper reports paired or multiple dates from 11 wooden sculptures dated as part of the Pre-Hispanic Caribbean Sculptural Arts in Wood project, which studied 66 wooden artifacts attributed to the pre-colonial Taíno, the indigenous peoples of the Caribbean's Greater Antilles. The calibrated ages of the pieces published here range from ∼AD 700–1500, indicating that the Taíno were producing elaborate sculptures much earlier than previously thought. The paired or multiple dates from these carvings confirmed the accuracy of the results, and were also used to construct a growth rate model of what was expected to be a slow-growing species (Guaiacum sp.). This model demonstrates that the boles used to create the sculptures grew on average 1 cm every 6–13 yr.

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.

Recently a cremation cemetery was excavated at the site of Wijnegem where 29 cremation graves and 9 funerary monuments were uncovered. Thirty radiocarbon (14C) dates were carried out, mostly on cremated bone but also 10 charcoal samples were dated. Twenty-four cremations were studied. Four ring ditches were dated by charcoal samples from the infill of the ditch. The 14C dates showed an interesting long-term occupation of the cemetery. Different phases were ascertained. The history of the cemetery starts in the northern part of the site around a circular funerary monument. Two cremations were dated at the transition of the Early to Middle Bronze Ages. Two other graves represent the transition from the Middle to the Late Bronze Ages. The main occupation period dates between the end of the Late Bronze Age and the Early Iron Age. Finally, an isolated cremation grave marks the definite abandonment of the site during the Late Iron Age.

Recent advancements in accelerator mass spectroscopic (AMS) radiocarbon (14C) analytical methods and instrumentation offer us reliable conventional 14C ages with highly reduced analytical uncertainty for archeological bone collagen. However, after calibration this may be still too high for archeologists in periods where archeochronology is capable of attaining a resolution of 25–30 yr. Furthermore, there are cases when wiggles in the calibration curve yield wider age ranges than initially expected. For the Avar Age in the Carpathian Basin (568 to early 9th century AD) reliable archeotypochronology is available for the 7th century AD alone. The date of Avar invasion (568 AD) is precisely known. Precise archeological dating for the late 6th and the 9th centuries is lacking, calling for other methods to be introduced. This paper reports the first 14C dates for an Early Avar Age cemetery, Makó-Mikócsa. According to archeotypochronology, the cemetery was in use for three generations until the mid-7th century AD. The imprecision in 14C chronology arising from wiggles in the IntCal13 curve was significantly reduced by relative stratigraphy-controlled Bayesian modeling. Introduction of further age constraints from archeotypochronology into the model reduces broad absolute age ranges providing more constraint ages.

Decommissioning of nuclear reactors requires determination of all remnant long-lived isotopes that were produced during their long functioning time of the respective facilities. Radiocarbon (14C) is such an isotope (T1/2 = 5730 yr), widely produced by neutron reactions in a thermal column of a nuclear reactor. Accelerator mass spectrometry (AMS) uses 14C for precise dating of up to 50,000 years old archaeological artifacts. This study presents a premier AMS measurement of high concentrated 14C samples that are strictly forbidden in laboratories dedicated to perform 14C dating. The determined 14C activities range from the natural level (isotopic ratio 14C/12C = 1.2 × 10–12) up to values of 10,000 times higher. 14C bulk and depth profile concentrations were measured in the thermal column disks of a decommissioned nuclear reactor. Results have shown that the 14C concentration in the thermal column, close the reactor core is about 75 kBq/g and decreases to 0.7 Bq/g and the end of the column. Such AMS measurements are applicable for decommissioning and waste management of nuclear reactors.

Our ability to reliably use radiocarbon (14C) dates of mollusk shells to estimate calendar ages may depend on the feeding preference and habitat of a particular species and the geology of the region. Gastropods that feed by scraping are prone to incorporation of carbon from the substrate into their shells as evidenced by studies comparing the radiocarbon dates of shells and flesh from different species on different substrates (Dye 1994; Hogg et al. 1998). Limpet shells (Patella sp.) are commonly found in prehistoric midden deposits in the British Isles and elsewhere, however these shells have largely been avoided for radiocarbon dating in regions of limestone outcrops. Results from limpets (Patella vulgata) collected alive on limestone and volcanic substrates on the coasts of Ireland indicate that the shells were formed in equilibrium with the seawater, with no significant 14C offsets. Limpets collected from the east coast of Northern Ireland have elevated 14C due to the output of Sellafield nuclear fuel reprocessing plant. In all locations, the flesh was depleted in 14C compared to the shells. The results will have an important consequence for radiocarbon dating of midden deposits as well as the bone of humans and animals who fed on the limpets.

Fossil fuels are of utmost importance to the world we live in today. However, their use can cause major impacts on the environment, especially on water resources. In this regard, algae have been intensively used as a strategy for remediation and monitoring of environmental pollution due to its efficient absorption of contaminants. In this work, samples of seaweed collected in Niterói/RJ—contaminated with kerosene and diesel—were analyzed by radiocarbon (14C) accelerator mass spectrometry (AMS) and by n-alkane quantification with gas chromatography to evaluate bioaccumulation in function of the dosage of contaminants. The biogenic content measured by radiocarbon analysis resulted in 95.6% for algae contaminated with 10 mL of kerosene and 67.6% for algae contaminated with 10 mL of diesel. The maximum intensity of n-C17 n-alkane in algae with 5 mL, 10 mL, and 15 mL of diesel was 768.2, 1878.1, and 5699.2 ng.g-1, respectively. While the maximum concentration of n-C27 in algae with 5 mL, 10 mL and 15 mL of kerosene was 3.3, 35.9, and 150.3 ng.g-1. We concluded that, for both contaminants, their incorporation into algae increases as the contamination dosage increases, making this methodology an effective technique for monitoring and remediation of urban aquatic ecosystems.

The total 14C content and its speciation (inorganic/organic) were measured in spent ion exchange resins (SIERs) received from Cernavoda Nuclear Power Plant (NPP). Also, 14C release from SIERs was investigated by desorption tests carried out in alkaline solution relevant for cementitious environment disposal. The method used for total 14C measurement consists of combustion in oxygen-rich atmosphere, while for speciation measurements, both in SIERs and in desorption solutions, an analytical method based on acid stripping and wet oxidation was applied. Around 97% from the total 14C inventory measured on the Cernavoda SIERs (33.7 kBq/g) was found to be in inorganic form and only 7% as organic 14C. Under alkaline conditions, 14C could be released both as gaseous and as soluble species: from the total 14C present in the SIERs samples around 7% was released as inorganic 14C in the gas phase and 79% as dissolved species (mainly as inorganic 14C). These percentages were obtained for unconditioned SIERs in NaOH solution. The SIERs will be immobilized in a suitable matrix for disposal, and the presence of Ca ions dissolved in cement pore water favor precipitation of 14C and consequently the amount of 14C released from disposal area should be lower.

Peat, at depth 3.5 m, from upper of 2 layers, at village of Timoshkovichi [53° 35′ N Lat, 26° 05° E Long], Korelichi Raion, Grodno Oblast, Belorussian SSR. Timoshkovichi is located on Novogrudok upland, beyond limits of region of Valday [Wurm] Glaciation. Cross section synchronous with ancient ravine of Neman R. basin where 2 horizons of peat can be detected: the lower, according to pollen data, accumulated at time of Mikulino [Eem] Interglacial; the upper believed accumulated at time of 2nd climatic optimum of Mikulino Interglacial, or at time of early Interstadial of Valday [Wurm] Glaciation (Tsapenko and Makhnach, 1959). Coll. 1962 by N. S. Chebotareva, Geog. Inst., Acad. of Sci., USSR.

We report radiocarbon ages on cellulose isolated from the gut contents of a Diprotodon found at Lake Callabonna, South Australia. The maximum age obtained corresponds to a minimum age of >53,400 BP for this extinct giant marsupial. This is older than, and hence consistent with, the generally accepted Australian megafauna extinction window. We argue that dichromate and other strong oxidants are less selective than chlorite for lignin destruction in wood, and our results suggest that ages approaching laboratory background can be obtained using a repeated pretreatment sequence of chlorite-alkali-acid and measurement of the sometimes discarded 330°C combustion fraction.

A program of accelerator mass spectrometry has been started at the Rehovot 14UD Pelletron Accelerator Laboratory. Part of the initial emphasis has been directed to the detection of the 36Cl radioisotope. We report here on the present status of our work and describe our experimental system. Preliminary results are presented, showing that 36Cl/Cl concentrations ranging down to 1×10−14 could be measured with our system.

The palynological sequence of the Hula L07 core was previously correlated with the global oxygen isotope stages 3–5, based on a radiocarbon age determination and comparison with other Levantine paleoclimatological curves. An attempt was made to validate this correlation with Th/U dating. Unlike typical European peat, which is acidic, the soil pH of the Hula peat is mildly basic. Not only does this contribute to the oxidation of palynomorphs, but it also helps to preserve the carbonate material that can be a variable mixture of allogenic, endogenic, and authigenic components. Each component may represent a different degree of uranium series disequilibrium. The thorium (232Th) concentrations of the carbonate are low. Total digestion or acid leach of the sample may not always enable the proper correction for initial thorium. The dating derived from a NaOH-extraction of the organic material, while giving apparently better ages, also suffers from the presence of the carbonate admixture. It appears that, while 14C dating can be considered suitable for the younger portions of the core, techniques based upon the U-series may not be as efficacious in dating this important record of climatic change.

The following list presents results of dating archaeological samples from excavations in Africa. Most results reported in this list were obtained from 1982 to 1993 for international research projects studying the origin and early development of food-producing cultures in northeastern Africa, including the Nile basin and the Sahara. Detailed information on these projects may be found in the series of conference proceedings edited by Krzyżaniak and Kobusiewicz (1984, 1989, 1993).

We quantified the rate of carbonate dissolution with increasing water depth by taking the difference in the carbonate mass accumulation rate of deep (3393–4375 m) core top sediments from the shallowest one (3208 m), which we assumed was unaffected by dissolution. This method depends on high quality 14C dates that we calibrated to calendar years for calculating sedimentation rates. Our results show low (ranging from 0 to 0.3 g cm−2 ka−1) and high (ranging from 1.5 to 1.7 g cm−2 ka−1) carbonate dissolution rates, above and below 4000 m, respectively. Therefore, we interpret the sudden increase in the carbonate dissolution rate at 4000-m water depth to mark the lysocline.

The Rio Grande Cone is a major fanlike depositional feature in the continental slope of the Pelotas Basin, Southern Brazil. Two representative sediment cores collected in the Cone area were retrieved using a piston core device. In this work, the organic matter (OM) in the sediments was characterized for a continental vs. marine origin using chemical proxies to help constrain the origin of gas in hydrates. The main contribution of OM was from marine organic carbon based on the stable carbon isotope (δ13C-org) and total organic carbon/total nitrogen ratio (TOC:TN) analyses. In addition, the 14C data showed important information about the origin of the OM and we suggest some factors that could modify the original organic matter and therefore mask the “real” 14C ages: (1) biological activity that could modify the carbon isotopic composition of bulk terrestrial organic matter values, (2) the existence of younger sediments from mass wasting deposits unconformably overlying older sediments, and (3) the deep-sediment-sourced methane contribution due to the input of “old” (>50 ka) organic compounds from migrating fluids.

The radiocarbon dating laboratory has been in operation since 1984 at the Radiation Center of Osaka Prefecture (OR), predecessor of the Research Center of Radioisotopes, University of Osaka Prefecture. We use liquid scintillation counting (LSC), following sample conversion to methanol through combustion and LiAlH4 reduction. This method was developed by Yamada et al. (Yamada, Higashimura and Shidei 1966; Yamada and Kobashigawa 1986). In cooperation with Yamada, we somewhat modified their procedure: 1) sample charcoal is burned at 700° in the presence of CuO needles and Sulfix grains to remove sulfur and halogen compounds produced during the combustion; 2) the combustion is carried out by using N2-O2 mixed gas of minimized O2 content and stopped when a small amount of the charcoal still remains unchanged, because precise investigation of methanol preparation revealed that O2 gas stimulates byproduct formation during LiAlH4 reduction (Shibata et al. 1985; Shibata et al. 1993). Usually, methanol is prepared directly from sample charcoal in a reaction apparatus (“direct method”). When the sample quantity is insufficient, generated CO2 is isolated as CaCO3 and diluted with inactive commercial CaCO3 if necessary (< 40 g of CaCO3 yield). Then CaCO3 is hydrolyzed with HCl to CO2 for methanol preparation in the usual way (“separate method”). We use standard oxalic acid SRM 4990C (HOxII) for determination of modern 14C (Stuiver 1983). The acid is oxidized to CO2 using the wet method of Valastro, Land and Valera (1977) followed by methanol preparation in the same manner as for unknown samples.

Radiocarbon measurements on organic carbon from the varved cores of Elk Lake, Minnesota suggest that the varve count may underestimate calendar years by 18% for the most recent 3800 varve years.

This list contains the results of measurements made during 1978 and 1979. Ages were computed on the radiocarbon half-life of 5568 ± 30 years. Statistical errors quoted herein are 1σ counting errors which include sample, background, and standard. The age limit reported is calculated on the basis of 3σ activity. The σ13C values in table 1 were measured by Krueger Enterprises, Inc, Geochron Laboratories Division1 and calculated based on Craig's Peedee Belemnite (PDB) limestone standard (Craig, 1957). The total alkalinity as bicarbonate values reported in table 1 was determined using techniques described by Brown, Skougstad, and Fishman (1970). Unless otherwise stated, all samples were collected and submitted by personnel of the US Geological Survey.

This list contains most of the measurements made during 1980, since our last list (R, 1981, v 23, p 33-37). A second methane synthesis unit became operational (Dauchot-Dehon and Van Strydonck, 1979) at the end of 1979. Basically, this unit is the same as the one built earlier (Klebert and Heylen, 1966).

The following list of dates is compiled from samples prepared since publication of our last date list (R., 1971, v. 13, p. 468-474). The counting equipment and operating procedures are the same. Ages are quoted with a lσ counting error which includes statistical variation of the sample count as well as for the background and standard, using a.d. 1950 as the reference year and 0.95% NBS oxalic acid for C14 dating as the standard. The half-life value used is 5570 years.