Since the early 1950s, the Sellafield nuclear fuel reprocessing plant in Northwest England has released radiocarbon into the Irish Sea in a mainly inorganic form as part of its authorized liquid effluent discharge. In contrast to the trend in which the activities of most radionuclides in the Sellafield liquid effluent have decreased substantially, 14C discharges have increased since 1994–95. This has largely been due to a policy change favoring marine discharges over atmospheric discharges. 14C is radiologically important due to its long half life, mobility in the environment, and propensity for entering the food chain. Current models for radionuclide dispersal in the Irish Sea are based on a reversible equilibrium distribution coefficient (kd), an approach which has been shown to be inadequate for 14C. Development of predictive models for the fate of Sellafield-derived 14C requires a thorough understanding of the biogeochemical fluxes between different carbon reservoirs and the processes controlling the net flux of 14C out of the Irish Sea, through the North Channel. In this study, both an empirical and a halving time approach indicate that close to 100% of the 14C that is discharged from Sellafield is dispersed beyond the Irish Sea on a time-scale of months in the form of DIC, with little transfer to the PIC, POC, and DOC fractions, indicating that the “dilute and disperse” mechanism is operating satisfactorily. This is consistent with previous research that indicated little transfer of 14C to Irish Sea sediments. While significant 14C enhancements have been observed in the biota of the Irish Sea, this observation is not necessarily in conflict with either of the above as the total biomass has to be taken into account in any calculations of 14C retention within the Irish Sea.

Some examples are given to show that the depth distribution curves of natural 14C and 13C of thin-layer sampled soil profiles can be used for inferring changes in soil organic matter and climate changes. By using a simple exchange model, we can determine whether decomposition products are fixed by clay or transported downward toward the groundwater table. We can also estimate the amount of the Greenhouse gases, CO2 and CH4, produced by the decomposition of the organic matter in terrestrial and paddy soils and emitted from the soil. A change from C3 to C4 plants, which might occur during a predicted temperature rise in some areas, thereby influencing the carbon balance, can be clearly detected by the δ13C depth profiles. A change in organic matter input can also be calculated under certain circumstances.

The radiocarbon dates reported in this list are almost all based on collagen measurements from human archaeologic bone material. This collagen was isolated according to the methods developed by Berger, Horney and Libby (1964), Ho, Marcus and Berger (1969), Longin (1971) and Protsch (1973). All samples were counted as CO2 gas at close to 1 atm in a 7.5L proportional counter with three energy channels. The 14C dates reported are calculated with the Libby half-life of 5568 ± 30 years as required by convention. 13C measurements were used to normalize to −25‰ in the standard manner. The biospheric standard is 95% the count rate of NBS oxalic acid for radiocarbon laboratories. Background is based on CO2 obtained from marble. The accuracy of counter operation is checked against historically dated wood from the funerary boat of Sesostris III, 1872−8 +4 bc (Hayes, 1962). The 14C ages are not tree-ring calibrated.

Direct dating of prehistoric paintings is playing a major role in Paleolithic art studies. Very few figures can be directly dated since the necessary condition is that they contain organic carbon-based material. Thus, it is very important to check the presence of organic carbon-based material in situ before sampling in order to protect the visual integrity of the paintings or drawings. We have tested and compared 3 different portable analytical systems that can be used in cave environments for detecting carbon in prehistoric paintings: (1) a very compact X-ray fluorescence (XRF) system in Villars Cave (Dordogne, France); (2) a portable micro-Raman spectrometer in Rouffignac Cave (Dordogne, France); and (3) an infrared reflectography camera in both caves. These techniques have been chosen for their non-destructiveness: no sample has to be taken from the rock surface and no contact is made between the probes and the paintings or drawings. The analyses have shown that all the animal figures have been drawn with manganese oxides and cannot be directly dated by radiocarbon. However, carbon has been detected in several spots such as black dots and lines and torch marks. 14C results were obtained from 5 torch marks selected in Villars Cave, with ages between 17.1–18.0 ka cal BP. Three methods were used to identify carbon in black pigments or to confirm the presence of torch marks by carbon detection. Thanks to these new analytical developments, it will be now possible to select more accurately the samples to be taken for 14C dating prehistoric paintings and drawings.

Sediment from Lake Boeckella, Antarctic Peninsula, is richer in Ca, Cd, Cu, P, Sr and Zn than that of six other lakes in the area. The elements originate from Adélie penguin (Pygoscelis adeliae) guano on the lake shores. Changing Cu and P concentrations in the lake sediment are used as a proxy for penguin influence on the lake sediment from ca. 5850 bp to present. A 14C dating model suggests that the 14C correction factor in the lake sediments depends on the penguin proxy, the apparent age of the penguin guano and the amount of particulate carbon originating from the carbon-bearing shales in the watershed. Glacial meltwater and dissolved carbonates do not contain enough “old” carbon to contribute significantly to the correction factor. Ages corrected with the 14C dating model agree with the depth vs. age curve based on independently 14C-dated tephra horizons. The reservoir effect has been constant since at least 5800 bp, implying long-term stability of the currents and water masses in the area. The existing chronology for Lake Boeckella has been recalculated. The period of glacial advance, previously thought to have culminated at 5000 bp, is now thought to have culminated at 4700 bp; deglaciation of the area is thought to have occurred at 6300 bp instead of 8680 bp.

The Saquarema archaeological site, on the Atlantic coast of the Rio de Janeiro State, is one of many shellmounds built on the Brazilian coast by hunter-gatherer populations during the Holocene. We used archaeological material from this site with the aim of evaluating the marine reservoir effect (MRE) in the region. Radiocarbon ages of 45 marine and 6 terrestrial samples from this shellmound provided data for assessing the MRE and the influences of freshwater and seasonal coastal marine upwelling in this specific locality. Samples of charcoal, fish otoliths, and mollusk shells were analyzed and the 14C dates were modeled in the OxCal platform to determine the marine reservoir correction. The result obtained is R = 265 ± 70 14C yr and the offset ΔR was found to be –140 ± 66 14C yr. To support the accuracy of this value for correcting conventional 14C marine ages, taxonomic analyses of the samples were performed.

Specific activities of radiocarbon in annual tree rings corresponding to 1980-2009 are reported for a pine tree located 2 km from the Qinshan Nuclear Power Plant (Qinshan NPP), China. While a negligible enhanced 14C activity due to operation of the Qinshan NPP Plant I is evident, a relative increase (1.8–62.6 Bq/kg C) was observed in the specific activity after operation of the Qinshan NPP Plant II in 2002 and Plant III in 2003. The enhanced values were primarily affected by the 14C discharged from Plant III (CANDU-type reactor), and a good correlation was found between the 14C discharged from Plant III in the growing season and the 14C excess value. The excess 14C activities peaked in 2005 (at 302.0 Bq/kg C, which is 62.6 Bq/kg C above the “clean air” 14C level), and then declined due to the improvement in 14C discharge management of Plant III. In 2009, the 14C-specific activity was near the background level.

The list of age measurements given below was obtainedfrom December 1965 to October 1966, Nearly allarchaeologic samples dated come from Italianterritory, a few from Europe, Asia, and Africa. Someof the series continue or complete measurementspublished in previous lists (Rome II, III and IV)and refer to important deposits whose material, theresult of several excavation campaigns, has beensubmitted at different times to our laboratory. Allgeologic samples come from Italian territory.

Laminated sediments of Gościaż Lake can be used as an independent source of material for calibrating the radiocarbon time scale. The varve chronology is based on three long cores from the deepest part of the lake, with one additional core from the second deepest part. From pollen and Cladocera spectra and stable isotope and chemical content sequences, we have determined the Allerød(AL)/Younger Dryas(YD) and Younger Dryas/Preboreal(PB) boundaries in the three long cores with relatively good accuracy, and have tentatively defined the AL/YD boundary in the fourth core. The Younger Dryas period contains at least 1520 varves, with 980 varves in fragments well replicated in all four cores. The duration of the Younger Dryas as recorded in sediments of Gościaż Lake corresponds well to the duration derived from 230Th/234U and 14C dates on Barbados corals, but disagrees with estimates from Soppensee, Lake Holzmaar and Swedish varves. Two AMS dates of terrestrial macrofossils from the PB and YD periods seem to fit both the data obtained for Swiss lake sediments and Barbados corals.

Dating ice samples from glaciers via radiocarbon is a challenge that requires systematic investigations. This work describes an approach for extraction and accelerator mass spectrometry (AMS) 14C analysis of the particulate organic carbon (POC) fraction in glacier ice samples. Measurements were performed at VERA (Vienna Environmental Research Accelerator) on ice samples obtained mainly from the non-temperated ablation zone of the Grenzgletscher (Grenz Glacier) system (Monte Rosa Massif, Swiss Alps). The samples were obtained from 2 sampling sites situated roughly on a common flow line. The sample masses used were between 0.3 and 1.4 kg of ice, yielding between 18 and 307 μg of carbon as POC. The carbon contamination introduced during sample processing varied between 5.4 and 33 μg C and originated mainly from the quartz filters and the rinsing liquids used in processing. Minimum sample sizes for successful graphitization of CO2 in our laboratory could be reduced to <10 μg carbon, with a background in the graphitization process of ∼0.5 μg of 40-pMC carbon. Evaluation of the whole procedure via 11 Grenzgletscher samples revealed a surprisingly large scatter of pMC values. We obtain a mean calibrated age of 2100 BC to AD 900 (95.4% confidence level), which is not significantly different for the 2 sampling sites. Discussions of these results suggest that single 14C dates of glacial POC are presently of limited significance. Future improvements with respect to analytical precision and sample characterization are proposed in order to fully explore the POC dating potential.

14C ages were determined on samples of foraminifera separated from cores from three areas of the tropical Pacific (East Pacific Rise, Oontong Java Plateau, and South China Sea). Analyses were made on four planktonic species and on mixed benthics. The purpose of the multiple analysis on planktonic species is to assess the importance of artifacts resulting from the bioturbation-abundance change couple, from the bioturbation-partial dissolution couple and from redeposition by bottom currents. The goal is to use the benthic-planktonic age difference as a means of establishing changes in deep sea ventilation rate over the past 25,000 years. Results of a part of this work are presented in this paper.

Dendrochronological studies have begun on two conifer species in the Stanley River area of western Tasmania. The chronology extends to 273 BC for Huon pine (Lagarostrobos franklinii) and to AD 1450 for celery-top pine (Phyllocladus aspleniifolius). Apart from living or recently felled trees, sections have been taken from 58 logs preserved in floodplain sediments. Two of these logs have late Pleistocene ages, centered around 13.0 and 12.7 k 14C yr bp. Four logs are between 8 and 9 ka BP, and one is centered at 7.3 ka bp. The remaining logs have various ages between 6.2 ka BP and the present. 14C measurements have been performed on decadal samples from the two late Pleistocene logs, providing short (260-yr) records of atmospheric 14C variations when plotted against individual ring numbers. Decadal measurements on the 7300-yr-old log have been wiggle-matched with 14C calibration curves from German oak and bristlecone pine. Measurements for the period, AD 1600–1800, show good agreement with northern hemisphere results, and a nearly zero offset between the hemispheres.

The chemical extraction of soil organic carbon (SOC) fractions from soils often does not produce satisfactory results for radiocarbon dating. In this study, a sequential pyrolysis technique was investigated. The soil was pyrolyzed at temperatures of 200, 400, 600, and 800 °C to partition organic carbon into pyrolytic volatile (Py-V) and pyrolytic residue (Py-R) fractions. The preliminary results show that the 14C dates of both fractions become progressively older as the pyrolysis temperature is increased. In addition, the ages of the Py-V fractions are consistently younger than the corresponding Py-R fractions extracted at the same temperature. Experimental results of known-age paleosol samples indicate that the Py-V fractions obtained between 600 and 800 °C yield the most reliable ages. This technique provides a new approach to improve the accuracy of 14C dating of loess-paleosol sequences.

Radiometric dating of glacier ice is an essential tool where stratigraphic dating methods cannot be applied. This study focuses on Alpine glacier ice and presents a new sample preparation system for dating of glacier ice samples via radiocarbon (14C) dating of the microscopic particulate organic carbon (POC) fraction incorporated in the ice matrix. An adaptable, low-cost inline filtration-oxidation-unit (REFILOX) has been developed, which for the first time unifies all sample preparation steps from ice filtration to CO2 quantification in one closed setup. A systematic 14C investigation of modern European aerosol samples revealed that a POC combustion temperature of 340°C provides the best representation of the real sample age. A very low process blank of maximally 0.3±0.1 µgC now enables 14C dating of high Alpine ice samples, where POC concentrations are generally low (typically 10–50 µgC/kg), in an ice sample mass range of 300–500 g. In a first successful application, the method was used to obtain age constraints for an ice core from the cold, high Alpine firn saddle Colle Gnifetti (Switzerland). Analysis of the bottom ice core sections revealed a basal age of 4171–3923 cal yr BP but also a so far enigmatic discontinuity in the age-depth relationship.

It is well known that 14C dating of fossil bone with seriously depleted protein levels, or bone that has been consolidated with preservatives, can produce erroneous results. In the tropics, warm and moist soil conditions lead to constant reworking of organic matter and add to the danger of bone contamination. Because of this, 14C dating of preservative-impregnated bone from such areas has rarely been successful. We report here a set of AMS dates on both unconsolidated animal bone and polyvinyl acetate/polyvinyl alcohol (PVA/PV-OH) impregnated human burials from the Maya site of Cuello, Belize. The steps needed to purify the samples are described, together with details on the use of qualitative infra-red (IR) spectra as a means of assessing sample purity.

The following is a list of dates obtained since the compilation of List XII. The method is essentially the same as described in that list. Two CO2-CS2 Geiger counter systems were used. Equipment and counting techniques have been described elsewhere (Crane, 1961). Dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) a.d. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In Michigan date lists up to and including VII, we quoted errors at least twice as great as the statistical errors of counting, to take account of other errors in the over-all process.

To be able to successfully measure radiocarbon with accelerator mass spectrometry (AMS) in atmospheric aerosol samples, graphitization of small sample sizes (<50 μg carbon) must provide reproducible results. At Lund University, a graphitization line optimized for small samples has been constructed. Attention has been given to minimize the reduction reactor volume and each reactor is equipped with a very small pressure transducer that enables constant monitoring of the reaction. Samples as small as 25 μg of carbon have been successfully analyzed, and the mass detection limit of the system has probably not been reached.

This list presents dates on a portion of the samples measured at ISOTOPES since publication of Isotopes V, and for previously analyzed samples for which complete sample data are now available.

Samples were analyzed by gas proportional counting of carbon dioxide at 3 atm pressure in counters of 1 1. volume. Each sample was assayed twice, in different counters and on different days.

Procedures employed in sample preparation and age calculations have been described previously (Isotopes V).

Since the sensational 2003 announcement that pushed the start of the Yayoi period back by 500 yr, archaeologists working on 1st millennium BC material from northeast Asia have had to switch from the older short chronology to a new long chronology. However, this change need not apply to the entire northeast Asian region as China's chronology is tied to written records. The timeline of the Korean peninsula, intermediate between the Chinese and Japanese ones, needs to be reexamined. The chronology of the 1st millennium BC in the Korean peninsula is still in dispute, in part because many of the radiocarbon dates lack clear archaeological contexts. This paper shows that a reliable typological relationship observed in archaeological materials existed at this time linking northeast Asia from China to Japan. This paper includes absolute dates based on the initial AMS 14C measurements of charred crops from South Korean sites.

Previous stable isotope studies of modern and archaeological faunal samples from sites around Lake Mývatn, within the Mývatnssveit region of northeast Iceland, revealed that an overlap existed between the δ15N ranges of terrestrial herbivores and freshwater fish, while freshwater biota displayed δ13C values that were comparable with marine resources. Therefore, within this specific ecosystem, the separation of terrestrial herbivores, freshwater fish, and marine fish as components of human diet is complicated when only δ13C and δ15N are measured. δ34S measurements carried out within a previous study on animal bones from Skútustaoir, an early Viking age settlement on the south side of Lake Mývatn, showed that a clear offset existed between animals deriving their dietary resources from terrestrial, freshwater, and marine reservoirs. The present study focuses on δ13C, δ15N, and δ34S analyses and radiocarbon dating of human bone collagen from remains excavated from a churchyard at Hofstaoir, 5 km west of Lake Mývatn. The results demonstrate that a wide range of δ34S values exist within individuals, a pattern that must be the result of consumption of varying proportions of terrestrial-, freshwater-, and marine-based resources. For that proportion of the population with 14C ages that apparently predate the well-established first human settlement of Iceland (landnám) circa AD 871 ± 2, this has enabled us to explain the reason for these anomalously old ages in terms of marine and/or freshwater 14C reservoir effects.