This list comprises age measurements carried out at the Institute from 1979 to 1981. Anticoincidence variant was applied to attain higher counting efficiency of a 2-channel scintillation device. The introduction of a plastic scintillator as an active guard around the detector in the 2π geometry decreases the influence of high energy cosmic radiation and reduces the background ca 35 to 75% (Rajamäe & Punning, 1980). The application of an active guard with 4π geometry has proved most effective; as a result, the background decreased 85% to 0.65cpm with the volume of scintillation cocktail 5ml. We have improved our methods for decreasing the actual error of the background. The application of a control channel and consideration of barometric effect results in the increase of dating limits of up to 5000–6000 years (Rajamäe, 1981). Samples are calculated using a half-life of 5568 ± 30 years for 14C. Results are reported in years before 1950. δ13C measurements were performed on the mass-spectrometer MI-1201 and are reported with PDB as a reference standard. The reproducibility of results is ±0.2‰.

At the 12th International Radiocarbon Conference held in Trondheim, the potential of the London Underground as a site for liquid scintillation counting was considered (Bowman, 1986). This was discussed in light of a survey of three possible locations using a portable gamma-ray spectrometer. Two liquid scintillation counters, a Packard 3255 and an LKB “Kangaroo”, have now been successfully installed in a vault which is some 30m below ground. The reduction in background count rates achieved is discussed, together with other improvements made to the counting system.

The following list of dates was compiled since 1971, (R., 1971, v. 13, p. 420-431). Procedures of measurements are essentially unchanged from those reported previously (R., 1964, v. 6, p. 31-36; 1966, v. 8, p. 423-429; 1971, v. 13, p. 420-431).

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; 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.

Radiocarbon dates, obtained from different human bones found in several tombs of the site of Son Peretó, are presented and discussed together with the stratigraphical evidence and the study of the material culture. The calibrated dates show that the tombs were built earlier than the main phase of occupation of the West Sector, therefore belonging to a necropolis linked to the Christian building prior to the transformation of the area into a habitation nucleus. The necropolis is 14C dated mainly to the 6th century AD. This is in good agreement with the chronology provided by ceramic materials.

14C dating results derived from an absolutely-dated 471-year tree-ring sequence from central European oak show a trend towards somewhat older dates than those for bristleconepine tree rings of the same age, but similar to those for Egyptian historical samples. Differences visible between these trend lines are not relevant considering the standard errors proposed by Clark (1975).

A simulation study for the separation of rare isotopes such as beryllium and aluminum was performed for a new beam line to be attached to the 3MV Tandetron accelerator at the accelerator mass spectrometry (AMS) facility of Seoul National University in Korea. The new beam line will also be used for other scientific applications, namely, ion implantations, Rutherford backscattering, and nuclear astrophysics experiments. It mainly consists of 30° and 100° deflection dipole magnets and drift spaces. A transfer matrix for the beam line was determined by the TRANSPORT code. Simulation of the rare isotope separation was performed by a ray tracing method using the TURTLE code. The simulation results, including the effect of the energy degrader, provide feasibility for the separation of isobars with small mass differences in 10Be-10B and 26Al-26Mg.

The number of paleoecological records for the Sierra Nevada of California has increased substantially since the compilation of Adam (1985). We examine here the geographical and temporal distribution of records within the range in order to identify areas for which “gaps” exist in our paleoecological knowledge. Seventy-two sites with paleoecological information are identified; these sites are dated with 234 radiocarbon dates. Sites occur primarily between ca. 36°N and 38°30'N latitudes, and from ca. 1000 m to over 3000 m elevation on both sides of the Sierran crest, although more sites have been analyzed on the west side of the crest than the east side. In general, packrat (Neotoma) midden series are located at the lowest elevations, meadow and marsh cores originate from mid-elevations, and lake sediments have been analyzed from the highest elevations. Significant gaps in our knowledge occur for much of the east side of the crest, for both sides of the range above modern treeline, and for time periods older than the latest Pleistocene.

In this study, we test the possibility of using databases of radiocarbon ages to estimate boundaries of climatic chronozones. The Alaska region was chosen and compared with chronozones of 2 European countries: Poland and the Netherlands. The study included setting up a database of 14C ages published for climatic records from Alaska. Some 974 14C determinations on organic samples were selected and used to establish chronozones for the Late Glacial and the Holocene for the Alaska region. The selected data were calibrated and a summed probability density function (PDF) was calculated. The shape analysis of the constructed frequency distribution of 14C dates on calendar timescales together with the assumption about preferential sampling seems to be a useful tool for establishing calendar ages for boundaries of climatic periods, i.e. chronozones.

To investigate the relationship between paleoenvironmental changes and marine reservoir effects, the radiocarbon ages of marine bioclasts and terrestrial plants from the same horizons of a sediment core in the Holocene Epoch were measured. This core, with a length of approximately 9 m, was obtained from the southern part of the Miyazaki Plain southeast of Kyushu Island, which faces the Kuroshio warm current. This drilling site is located in an uplift area associated with the subduction of the Philippine Sea Plate. Based on analyses of lithology, molluscan and foraminifera assemblages, and radiocarbon dating, we interpreted four sedimentary units in order of age: tidal flat, inner bay, Kikai-Akahoya volcanic ash, and delta plain. These paleoenvironmental changes were mainly associated with the sea-level rise during the deglacial period. The reservoir ages of nine pairs from the tidal flat to inner bay facies were found to be from the time span of 7300–8200 cal BP. The chronological changes in the reservoir effect are correlated with those seen in Holocene sediments of the other coastal area in East Asia.

We developed a simple and cost-effective method for extracting carbon from dissolved inorganic carbon (DIC) in water samples without a carrier gas. This method only slightly modifies the existing vacuum line for CO2 purification in radiocarbon research laboratories by connecting several reservoirs and traps. The procedure consists of repeated cycles of CO2 extraction from water into the headspace of the reaction container, expansion of the extracted gas into the vacuum line, and cryogenic trapping of CO2. High CO2 yield (∼98%) was obtained from a variety of water samples with a wide range of DIC concentrations (0.4–100 mmol·L−1, in the case of 1.2 mgC). The δ13C fractionation depended on the CO2 yield, while the 14C concentration was constant within the error range, regardless of the CO2 yield. The average δ13C discrepancy between the results of this method and direct analyses made using the GC-IRMS was 0.02 ± 0.06‰. The standard deviations (1σ) in fraction of modern carbon (F14C) ranged from 0.0002 to 0.0004 for waters below 0.01 of F14C, and below 0.8% of F14C values for waters above 0.1. We conclude that this method is useful for effectively extracting CO2 from DIC in water and yields accurate 14C data.

14C ages were obtained for the Australian lakes recorded below in order to complement research into their magnetic stratigraphy and sedimentology. It has been possible to establish precise 14C chronologies in six separate lakes, and also to compare ages obtained from stratigraphically equivalent horizons in different parts of the same lake so as to determine the reproducibility of these ages.

The following list of measurements contains selected results obtained by the La Jolla Radiocarbon Laboratory from November 1966 to July 1971. During the same period 382 measurements were made on tree-ring-dated wood in studying secular variations of the atmospheric C14 level and of the absolute radiocarbon time scale [Suess, 1970a, 1970b]. Results of these measurements are not included here. Also not included are 124 measurements of C14 determinations in extraterrestrial material and results of other occasional investigations will be published elsewhere.

The dates presented in this paper comprise results of determinations made on archaeologic and geologic material from Socialist Republic Vietnam since 1969. Radioactivity was measured twice for 48 hours with gas proportional counters of Houtermans-Oeschger type, using methane at 1000mm Hg pressure as filling gas. Influence of cosmic and local environmental radiation on the counters was reduced with 30 tons of shielding material as described earlier (R, 1970, v 12, p 400-420).

Procedures and equipment of the laboratory have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH and dilute H3PO4 before conversion to the counting gas methane, marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4.

We investigated the radiocarbon ages and carbon and nitrogen isotope ratios of human skeletal remains from burials at the Yuigahama-minami and Chusei-Shudan-Bochi sites in the Yuigahama area (Kamakura, Japan), which we believe are associated with the great attack on Kamakura by Nitta Yoshisada in AD 1333. The human bones produced enriched δ13C and δ15N values that could be affected by consumption of protein from marine fish and/or mammals with high δ13C and δ15N, and therefore older apparent 14C ages. We thus estimated the marine reservoir effect on human skeletons to determine their true ages. The IsoSource isotope mixing model was employed for reconstructing percentages of marine protein in the human diet, and calibrated calendar dates for the 14C ages were calculated using the marine percentages. At the Yuigahama-minami site, most skeletons from individual burials now date to the last phase of the Kamakura period or the early part of the Muromachi period, while skeletons from mixed human-animal multiple burials date to the latter part of the Kamakura period. The humans from the individual burials, consisting of normal ratios of adult males, could have died a natural death, though the site could also have been used to inter victims of the battle of 1333. The humans from mixed human-animal burials, consisting of a high proportion of infants, were not victims of the 1333 battle, but the site may have been used to inter victims of the Kamakura earthquake in 1293, which resulted in a catastrophic tsunami. On the other hand, the skeletons from multiple burials in the Chusei-Shudan-Bochi site all date to the middle Kamakura period. Coupled with the fact that most humans in the site are male but show no evidence of injuries by sword cuts, it is likely that burials of the Chusei-Shudan-Bochi site could have been a collective interment following the Jinji earthquake in 1241, the Shoka earthquake in 1257, or the Shoka famine in 1258 in the middle Kamakura period. The results of this study indicate that humans from burials in the Yuigahama region were not necessarily victims of the attack by Nitta Yoshisada on Kamakura, but instead were likely victims of natural disasters such as large earthquakes and severe famines, which often occurred in the middle Kamakura period.

We present here the analysis of the radiocarbon concentration and the components deposited on 2-year-old Pinus sylvestris L. needles collected in 2021, which were exposed to air contaminants for approximately two years. The needles were collected from seven sampling sites located near roads, households, and industrial factories in Silesia, the most industrialized part of Poland. The radiocarbon concentration was investigated using liquid scintillation spectrometry. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to quantitatively analyze the elements deposited on the surface of pine needles. The depletion of the radiocarbon concentration in pine needles relative to clean air was observed at most of the investigated sites. Although it has been observed that in the research area, the fossil fuel CO2 emission ranging from 0.4 to 3%, we cannot exclude that Suess effect may be underestimated due to biomass burning and mixing of the 14CO2 origin from different sources. A significant amount of silicon, nitrogen, and sulfur was commonly found in samples, Metal elements of Ca, Fe, Al, Mg, and K were also present in most samples. Heavier elements of Fe and Ti were present in higher concentrations only in needles obtained from sites nearer to the heat and power plant in Łaziska Górne.

The results of the Glasgow Intercomparison Project and discussions about ways to increase a laboratory's quality as well as an archaeologist's confidence led to a general agreement at the Workshop about the outline of a procedure for Quality Control and Assurance. The scheme is primarily based on proposals presented by Dr Austin Long, University of Arizona, Dr Roberto Gonfiantini of the International Atomic Energy Agency and our Glasgow hosts. It consists of three elements:

Hemiparasitic plants obtain water and solutes from their hosts, but much remains to be learned about these transfers. We used a forest girdling experiment to investigate how leaf gas exchange, carbon and nitrogen cycling in the root hemiparasite Melampyrum lineare Desr. responded to disturbance and changes in physiology of potential host trees. By preventing belowground C allocation by 35% of the canopy, girdling decreased the starch and soluble sugar contents of bulk forest floor fine roots. Photosynthetic rates of M. lineare were statistically significantly lower in the girdled plot, but their hypothesized drivers (foliar N, stomatal conductance and transpiration) had no statistically significant differences between girdled and non-girdled plots. However, M. lineare in the girdled plot had higher foliar C concentrations and Δ14C than in the control plot, suggesting possible photosynthetic down-regulation in the girdled plot due to influx of older (e.g., host-derived) C into the leaves of M. lineare. Within the girdled plot (but not the control plot), M. lineare foliar C concentrations were positively correlated with foliar Δ14C and δ15N, suggesting that M. lineare may respond to changes in both C and N biogeochemistry during the decline of dominant canopy species.