In a case study to assess the possibilities and limitations of determining the exact age of paper, we measured radiocarbon (14C) concentrations in bulk-paper cellulose and starch extracts from 20 known-age paper samples of the last 65 yr. As expected, 14C concentrations in single-seasonal grown starch extracts are in reasonably good agreement with post-bomb atmospheric 14C. In contrast, 14C concentrations in bulk-paper cellulose indicate apparent admixtures of tree-ring fibers spanning up to >50 yr. In a forensic investigation, combining 14C results from single-seasonal components like starch with those from long-lived fibers, could potentially enhance the precision of paper production-date estimates for samples made after 1955.

Biogeochemical analyses of eastern oysters (Crassostrea virginica) are frequently included in environmental monitoring and paleoecological studies because their shells and soft tissues record environmental and dietary signals. Carbon isotopes in the mineral phase of the shell are derived from ambient bicarbonate and dissolved inorganic carbon (DIC), while organic carbon present in soft tissue is of dietary origin. Mineral-bound organic matter within the carbonate shell matrix (“conchiolin”) is studied less frequently. The purpose of this study was to compare carbon isotope composition (δ13C and Δ14C) of conchiolin to those of shell carbonates and soft tissues in eastern oysters and assess the extent to which conchiolin can provide insight into paleoecological records. Eleven oyster specimens were live-collected from Apalachicola Bay, USA, as well as a set of environmental samples (water, sediment, and terrestrial plants). Overall, the δ13C values in all studied oyster tissue types record environmental signals related to carbon sources, with conchiolin being enriched in 13C by an average of 2.3‰ relative to bulk soft tissues. Δ14C values in oyster shell carbonates generally reflect the marine versus riverine source of DIC, while conchiolin Δ14C values are impacted by variable relative contributions of young and old organic matter. Environmental samples indicate a significantly large difference in Δ14C among sources, from –127‰ in particulate organic matter to approximately +15‰ in DIC. Conchiolin is significantly depleted in 14C relative to other tissue types, by as much as 56.6‰, posing a major obstacle to the use of conchiolin as an alternative material for radiocarbon dating.

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists (Steventon & Kutzbach 1983; 1984). Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH-Na4P2O7 and dilute H3PO4 before conversion to the counting gas methane; when noted, marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCl for 15 minutes, then dilute NaOH-Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCl, NaOH-Na4P2O7, and then dilute HCl again.

We Fourier transformed and filtered calibration curve data to compensate for the averaging effect of radiocarbon-dating sets of adjacent tree rings. A Wiener Filter was also applied to minimize the effects of the counting errors of the dates on the resulting calibration curve and to produce a least-squares curve through the data. The method is illustrated using a short 14C-dated tree-ring sequence from New Zealand to produce a calibration curve at yearly intervals for New Zealand matai (Prumnopitys taxifolia). The resulting curve has a nominal standard error of 10 ± 3 yr, which is ca. half the average standard error of the original raw data.

The following list contains most of the measurements of geologic samples made during 1979 and 1980 using carbon-dioxide-filled proportional counters. Samples with laboratory numbers > 1000 were counted with counter No. 1 (L1), and those with numbers < 1000, with counter No. 3 (L3), described by Mościcki and Zastawny (1977). Actual parameters of both counters were given in our previous date list (R, 1982, v 24, p 172).

Several articles reporting radiocarbon dates of Early Bronze Age (EB) material from excavations in the southern Levant have been published over the last 30 yr. The excavations conducted at Tell el-Hesi have produced material from which 2 additional 14C dates have been extracted to date. The 2 samples confirm the EB dating of Field VI material and suggest EB III settlement at Hesi might be earlier than previously reported based on pottery typology.

A complete description of the CO2-CS2 Geiger-counter system which is in operation at the University of Michigan Radiocarbon Dating Laboratory is available in mimeograph form, upon request to the author. It includes a report on research into the characteristics of the CO2-CS2 counter, as well as a full set of instructions and diagrams for the building of such a system for use in radiocarbon dating.

Radiocarbon dates obtained for the coastal hilltop settlement of Aghios Antonios Potos in south Thasos are statistically treated to define the absolute chronology for the start and the end of the various habitation and cultural phases at the site. The location was first occupied during the Final Neolithic (FN) between 3800 and 3600 BC, extending this much contested phase to the lowest up to now record for Thasos and the northern Greece. The site is continuously inhabited from Early Bronze Age I until the early Late Bronze Age (LBA; 1363 BC) when it was abandoned. Comparison with other sites in Thasos and particularly with the inland site of Kastri Theologos showed that the first occupation at Aghios Antonios came soon after the abandonment of Kastri in the beginning of the 4th millennium. In fact, after the decline and abandonment of Aghios Antonios in the LBA, the site of Kastri was reinhabited, leading to the hypothesis that part of the coastal population moved inland. The presumed chronological sequence of alternate habitation between the two settlements may evoke explanations for sociocultural and/or environmental dynamics behind population movements in prehistoric Thasos. A major conclusion of the project is that the 4th millennium occupation gap attested in many sites of Greece, especially in the north, is probably bridged in south Thasos, when the data from all sites are taken together. The mobility of people in Final Neolithic south Thasos may explain the general phenomenon of limited occupational sequences in the FN of north Greece.

The following list includes some measurements made from December 1982 to May 1985 in the Radiocarbon Dating Laboratory, Faculty of Science, University of Granada, of samples from Spain, Portugal, and the Sudan. Sample preparation techniques and benzene synthesis remain as described previously (R, 1982, v 24, p 217–221) and equipment and measurement of samples was also reported previously (R, 1985, v 27, p 610–615). Radiocarbon ages are calculated using the 14C half-life of 5570 years and 0.95 activity of NBS oxalic acid is used as modern standard. Sample descriptions are based on information provided by submitters. Age determinations were made with the help of Research Project 0925/81, CAICYT, Spain.

The wetland site of Verrebroek “Dok” situated in northern Belgium is one of the largest and best dated locations of Mesolithic material in northwestern Europe. Salvage excavations organized since 1992 at this large, unstratified open-air settlement have revealed more than 50 spatially independent artifact concentrations with traces of numerous fireplaces. Single entity dating of charred hazelnut shells from surface-hearths and charcoal from hearth-pits was used to obtain information not only on the sites duration, but also on the relation between the surface hearths and the hearth-pits. The dates were also used to look at discrepancies between the radiocarbon chronology and the typo-chronology of the lithic artifacts.

After the last damaging earthquake in 2012, an anti-seismic reinforcement project of the cathedral of Modena was designed giving us the opportunity to investigate and date the building materials. Radiocarbon (14C), optically stimulated luminescence (OSL), and thermoluminescence (TL) dating techniques were performed on the vaults with the aim to (1) clarify the construction timing, (2) define the history of the restorations, and (3) explore the possible correlation of the main restoration works to the earthquake chronology deduced from the historic catalog. Preliminary results show that medieval older bricks were reused for most of the original construction. Only lime and non-gypsum mortar was used for the original construction in the 15th century and for later repair of damage caused by earthquakes in the 16th and 17th centuries. Gypsum mortar was used for later repair in the 18th century. The results show much stronger damage due to earthquakes than previously thought.

As a main source of freshwater and particles, the Rhône River plays a major role in the biogeochemical cycle of organic carbon (OC) in the Mediterranean Sea. To better understand the origin of organic matter and the processes leading to its export to the coastal sea near the Rhône River, we measured radiocarbon (Δ14C) and stable carbon isotopes (δ13C) in the sediments of the delta, after density fractionation. In April 2007, 3 sites located along an offshore transect (A, C, and E) were sampled for surface sediments, and bulk sediment was separated into 4 fractions of different densities (<1.6, 1.6–2, 2–2.5, and >2.5 g cm−3). In order to better understand the evolution of the OC along the transect, we investigated the OC sources and their evolution for each density fraction. Bulk OC shows a large increase in δ13C from −27.2′ nearshore to −24.5′ at offshore stations while Δ14C decreased from 59′ to −320′. The distribution of δ13C with density displayed a convex pattern at all stations. Except for fraction >2.5 g cm−3, δ13C increases by 2.5′ between stations A and E, indicating a loss of terrestrial signature. The distribution of Δ14C versus density had a concave pattern at all stations: at a single station, it showed a large heterogeneity with a difference of 500–600′ between the <1.6 and 2–2.5 g cm−3 fractions. A decrease in Δ14C of −400′ among the different density fractions was observed along the offshore transect. The density fraction >2.5 g cm−3 had less variability, with an average δ13C of −24.6 ± 0.4′ and Δ14C of −370 ± 115′. Several processes may explain this distribution: retention in the prodelta of large particles; mineralization of all fractions during the transport and deposition in the delta and shelf sediments; and dilution of terrestrial particles in continental shelf pool.

Wasted tires are the great source of fuel and valuable components but could be a cause of environmental and land pollution. This study shows the detailed method for the determination of radiocarbon isotope (14C) concentration in tires and their pyrolysis products. Samples are taken from truck and passenger car tires in the form of shredded rubber, pyrolysis oil and recovered carbon black. Liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) techniques were used for the investigation at Gliwice Radiocarbon and Mass Spectrometry Laboratory, and National Laboratory for Age Determination, Trondheim, Norway. The results are in good agreement. Radiocarbon concentration of the rubber varies significantly because of its complex structure and composition within the tires. The 14C concentration values were found to be higher in pyrolytic oil compared to rubber, and greater in truck tires rather than car tires.

The following list comprises age measurements carried out during 1976 and 1977. The activity of 14C was computed by one- and two-channel scintillation devices (Punning et al, 1976; 1977). Ages are calculated using a half-life of 5568 ± 30 years for 14G with NBC oxalic acid as a reference standard. All dates are reported in years before 1950. 12C/13C measurements were not performed and results are not corrected for 13C fractionation.

This list contains the results of 14C determinations obtained at the laboratory in 1982–1983.

Inland water bodies contain significant amounts of carbon in the form of dissolved inorganic carbon (DIC) derived from a mixture of modern atmospheric and pre-aged sources, which needs to be considered in radiocarbon-based dating and natural isotope tracer studies. While reservoir effects in hardwater lakes are generally considered to be constant through time, a comparison of recent and historical DI14C data from 2013 and 1969 for Lake Constance reveals that this is not a valid assumption. We hypothesize that changes in atmospheric carbon contributions to lake water DIC have taken place due to anthropogenically forced eutrophication in the 20th century. A return to more oligotrophic conditions in the lake led to reoxygenation and enhanced terrigenous organic matter remineralization, contributing to lake water DIC. Such comparisons using DI14C measurements from different points in time enable nonlinear changes in lake water DIC source and signature to be disentangled from concurrent anthropogenically induced changes in atmospheric 14C. In the future, coeval changes in lake dynamics due to climate change are expected to further perturb these balances. Depending on the scenario, Lake Constance DI14C is projected to decrease from the 2013 measured value of 0.856 Fm to 0.54–0.62 Fm by the end of the century.

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH—NA4P2O7 and dilute H3PO4 before conversion to the counting gas methane; when noted, marls and lake cores are treated with acid only. Very calcareous materials are treated with HCL instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCL for 15 minutes, then dilute NaOH—Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCL, NaOH—Na4P2O7, and then dilute HCL again.

Coral skeletal structures can provide a robust record of nuclear bomb produced 14C with valuable insight into air-sea exchange processes and water movement with applications to fisheries science. To expand these records in the South Pacific, a coral core from Tutuila Island, American Samoa was dated with density band counting covering a 59-yr period (1953–2012). Seasonal signals in elemental ratios (Sr/Ca and Ba/Ca) and stable carbon (δ13C) values across the coral core corroborated the well-defined annual band structure and highlighted an ocean climate shift from the 1997–1998 El Niño. The American Samoa coral 14C measurements were consistent with other regional records but included some notable differences across the South Pacific Gyre (SPG) at Fiji, Rarotonga, and Easter Island that can be attributed to decadal ocean climate cycles, surface residence times and proximity to the South Equatorial Current. An analysis of the post-peak 14C decline associated with each coral record indicated 14C levels are beginning to merge for the SPG. This observation, coupled with otolith measurements from American Samoa, reinforces the perspective that bomb 14C dating can be performed on fishes and other marine organisms of the region using the post-peak 14C decline to properly inform fisheries management in the South Pacific.

An international consortium of radiocarbon (14C) laboratories was established to date the origin of the St. George’s Rotunda in Nitrianska Blatnica (Slovakia), because its age was not well established in previous investigations. Altogether, 20 samples of wood, charcoal, mortar and plaster were analyzed. The 14C results obtained from the different laboratories as well as between the different sample types were in good agreement, resulting in a 14C calibrated age of 783–880 AD (94.2% probability) for the Rotunda. Although the 14C results have very good precision, the specific plateau-shape of the calibration curve in this period caused the wide range of the calibrated age. The probability distribution from OxCal calibration shows, however, that about 86% of the probability distribution lies in the period before 863 AD, implying that the Rotunda could have been constructed before the arrival of Constantine (St. Cyril) and St. Methodius to Great Moravia. The Rotunda thus probably represents the oldest standing purpose-built Christian church in the eastern part of Central Europe.

The jungles of Linyun and Longlin Autonomous Prefecture, located in the heart of the southwestern Guangxi Zhuang Autonomous Region of China, are home to the oldest tea trees (Camellia sinensis) in the world. In the absence of regular annual rings, radiocarbon (14C) dating is one of the most powerful tools that can assist in the determination of the ages and growth rates of these plants. In this work, cores were extracted from large ancient tea trees in a central Longlin rain forest; extraction of carbon was performed with an automated sample preparation system. The 14C levels in the tree cores were measured using accelerator mass spectrometry (AMS) at the University of Tsukuba. These measurements indicated that contrary to conventional views, the ages of trees in these forests range up to ~700 years, and the growth rate of this species is notably slow, exhibiting a long-term radial growth rate of 0.039±0.006 cm/yr. It was demonstrated that 14C analyses provide accurate determination of ages and growth rates for subtropical wild tea trees.