Radiocarbon (14C) conclusively demonstrates that the very important Yarkon-Tanininm aquifer, named after the two springs where the drainage presumably occurs, is in actuality two distinct aquifers—Upper and Lower. The springs have higher 14C activities than the exploitation wells that surround them (all drilled into the Upper aquifer). The springs are situated at faults that allow the Lower aquifer water to rise due to its higher pieziometric head and drain along with the Upper aquifer. The Lower aquifer water flows rapidly along a path that includes a karstic system. The Upper aquifer flows more slowly, primarily through a system of cracks in the carbonate aquifer. The Upper aquifer groundwater in the Beer-Sheba extension flows northwards at approximately ~4–7 m/yr.

We studied a suitable procedure for preparing of water samples used in radiocarbon intercomparisons involving dissolved inorganic carbon (DIC). The water samples must have inter-batch consistency and stable 14C concentrations and no sterilizing agent (e.g., HgCl2) should be added, in order to avoid the production of hazardous material. Six water samples, containing widely different amounts and types of salts, DIC, and 14C concentrations (1–100 pMC), were prepared in order to assess the procedure. Sample consistency was investigated through δ13C and chemical compositions; their low variabilities indicate that our procedure can be applied to radiocarbon intercomparison. A specific sample preparation protocol was developed for this kind of applications.

The stratigraphic succession of the Mar Piccolo basin (Gulf of Taranto, Southern Italy) is well known in the scientific literature dealing with the last interglacial since its morphological evolution is influenced by sea level changes during Late Pleistocene-Holocene. The local Holocene sea level history is well known thanks to data deriving from peat and ash layers identified in different sediment cores obtained underwater and in coastal areas. Peat sediments are frequently interlayed with muddy-sand beds rich in Cerastoderma glaucum (Poiret, 1789). In the literature of the Mediterranean basin, AMS 14C dating on C. glaucum is widely used also in paleo-environmental reconstruction because this bivalve is considered an useful marker of sea level, though in lagoonal systems, large age offsets have been reported in different areas. Due to the availability of precise chronological and geochronological markers, in order to validate the use of C. glaucum in paleo sea level reconstruction, AMS 14C dating campaign was carried out on this bivalve deriving from several cores drilled in the Mar Piccolo basin and its nearby areas. Nineteen AMS 14C dating analyses carried out on C. glaucum sampled from different sediment cores up to a maximum of 30 m from the seafloor are presented. These results show an inconsistency of the ages in relation to a sea-level rise reconstruction model. The interpretation of the data was performed after the estimation of the local age offset calculated by analyzing six live samples, collected in 2017 in Mar Piccolo and in Croatia, and two samples dated to 1968–1969. The results show that for both the classes of samples (2017 and 1960s) an age offset ranging from 600 to 800 yr can be estimated.

Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0–1.5 and mass range 6 μg–2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently “blank correct” measured unknowns in the mass range 25–100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented.

The elk/moose (Alces alces) was an important resource for prehistoric societies. In prehistoric art, it is often depicted in connection with water. Biologists find that elk spend much time in water and consume considerable amounts of aquatic plants. As freshwater plants can have reservoir ages of hundreds or even thousands of years, there is a risk of a significant reservoir effect in elk bones and antler, and artifacts made of these materials. This pilot study followed several approaches to investigate the possibility of a freshwater reservoir effect in elk. I analyzed modern, historical and archaeological bones and antler from several sites across Eurasia. Skull bone and antler of the same individual were radiocarbon dated, as antler is formed in summer, when the proportion of aquatic diet is supposed to be highest. Age offsets measured in this study were zero to about 500 years. A difference between bone and antler could not be determined. The reservoir effect appears to be smaller than estimated from accounts of elk diet, even in regions where a substantial freshwater reservoir effect is expected. Therefore, the hypothesis of a large proportion of aquatic diet can be rejected for several of the individuals studied here.

The bomb-peak signal preserved in the Arches® cotton paper was used to detect art forgeries imitating the work of Chinese artist T’ang Haywen (1927–1991). The dating of seven legitimate T’ang Haywen art pieces showed that the timing of the paper production was consistent with the artist’s use of Arches® paper starting in the early 1980s. The measured F14C of the paper from the 14 suspected forged paintings shows that the support material was produced in the last decade (2008–2011), therefore the art pieces could not be genuine T’ang Haywen works.

Over the past 30 years, the format of the radiocarbon (14C) intercomparison studies has changed, however, the selection of sample types used in these studies has remained constant—namely, natural and routinely dated materials that could subsequently be used as in-house reference materials. One such material is peat which has been used 12 times, starting with the ICS in 1988. Peat from Iceland (TIRI), Ellanmore (TIRI), Letham Moss (ICS, VIRI, and SIRI), and St Bees, UK (FIRI and VIRI) have been used, as well as a near-background peat from Siberia. In the main, these peat samples have been provided as the humic acid fraction, with the main advantage being that the humic acid is extracted in solution and then precipitated (the solution phase providing the homogenisation) which is a key requirement for a reference material. In this paper, we will revisit the peat results and explore their findings. In addition, for the last 8 years, the Letham Moss sample has been used in the SUERC 14C laboratory as an in-house standard or reference material. This has resulted in several thousand measurements. Such a rich data set is explored to illustrate the benefits arising from the intercomparison program.

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.

To determine the 237Np concentration originating from global fallout in the environment, samples were collected from Guangxi, south of China, and measured by accelerator mass spectrometry (AMS) at CIRCE. Serials standard samples and environment samples were prepared and measured using 242Pu as a tracer. The result indicates that the detection limit of 237Np as low as 10–15 g can be obtained. The concentration of 237Np in the environmental samples is less than 49.09 pg/kg (i.e. 1.280 mBq/kg), and the most probable value of 237Np is approximately 20 pg/kg (i.e. 0.53 mBq/kg).

The trajectory of the Kuroshio, the western boundary current in the north Pacific, influences regional climate. It intrudes into the South China Sea (SCS) through the Luzon Strait, resulting in the exchange of water, nutrients, heat, and salt between the Pacific and SCS. It has been reported that the trajectory of the Kuroshio has varied with decadal climate changes. However, there has been no report of an observation-based estimate of the variation in the Luzon Strait transport. Here, a 50-year, high-resolution coral skeletal radiocarbon (Δ14C) dataset from 1946 to 1994 is reported from Currimao, northwest of Luzon Island. Δ14C has been used as a sensitive tracer of seawater, and our data indicates a significant increase in Δ14C from 1946 to 1994 related to atmospheric nuclear bomb testing, with more rapid increase in the SCS than in the Pacific. The unusual, rapid Δ14C increase in the 1950s found in our SCS corals together with seasonal variation in Δ14C will helps constrain physical oceanographic models for the western Pacific, including the SCS.

We have investigated the possibility of direct accelerator mass spectrometry radiocarbon (AMS 14C) measurement of carbonate samples at ANSTO using the STAR 2 MV tandem accelerator. Each carbonate sample was powdered, mixed with metal powder and pressed into an aluminum cathode for direct carbonate measurement by AMS 14C. Of the three high-purity metal powders (Fe, Nb, and Ag) used in our investigation, Nb was found to be the best metal, which delivered higher carbon beam currents and lower background. Beam currents for targets containing the optimal carbonate mass of 1.5–2.0 mg were ∼8% of those obtained from graphite targets of standard size (>0.5 mg C). Typical measured blank for Carrara marble (IAEA-C1) of ∼40 ka was obtained. Background-corrected 14C values of carbonate targets agreed well with their associated values obtained from high-precision analysis of graphite targets within 2σ uncertainties. Typical precision of this rapid AMS analysis was ∼1% for samples <8 ka. Despite lower precision for carbonate target ages (compared to standard graphite target ages), these ages are useful for palaeobiological applications where a large number of dates are required, such as time-averaging studies.

High Voltage Engineering Europa (HVE) has designed a vacuum-insulated tandem accelerator dedicated to radiocarbon (14C) analysis. A unique feature of the design is a magnetic charge state selector that is incorporated in the high voltage terminal, which reduces the primary source of background that originates from the injection of 13CH− to negligible levels. As a result, background levels in the low 10−16 regimes are anticipated, thus supporting the most stringent 14C dating applications. Another feature of the system is the incorporation of several slit feedback loops for stabilization of the position of the ion beam throughout the system, which avoids drift and ensures stable, long-term operation. Finally, this article presents measurements and quantitative analysis of background contributions from 13CH−.

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.

This work summarizes the methodical capabilities, improvements, and new developments in the radiocarbon laboratory of the accelerator mass spectrometry (AMS) facility at the University of Cologne, Germany, which was established in 2010. During the past years, the laboratory has specialized in the analysis of small and gaseous samples. We thus, recently installed a second ion source dedicated for radiocarbon (14C) analysis of CO2 samples at our 6 MV Tandetron AMS from High Voltage Engineering Europe B.V. that is coupled with the gas injection system from Ionplus and an EuroVector EA 3000 elemental analyzer. This work summarizes all pretreatment methods and analytical facilities established in our laboratory during the last years including 14C analysis of individual organic compounds and of CO2 trapped on molecular sieves. We also report different blank values including our long-term blank since 2011, which is for normal-sized, solid samples (650–1000 µg C) 0.0012 ± 0.0004 F14C (54,305 ± 2581 yr BP, n = 484). The precision obtained for modern samples measured as graphite is 0.5% and for gaseous samples injected with the GIS ≤2%.

To identify chronological changes in the marine reservoir effect in southwest Japan, the radiocarbon ages of eight pairs of marine shells and terrestrial plants were measured from the same horizons of one core of Holocene sediments. This core was obtained from the northern part of the Sukumo Plain in southwestern Shikoku Island, which faces the warm Kuroshio Current. The drilling site is located in an area of subsidence associated with the convergence of the Philippine Sea Plate and the Eurasian Plate. On analyses of lithology, molluscan assemblages, and radiocarbon dating, we interpreted, from oldest to youngest, nine units: basement rock, a braided river channel, a meandering river channel, an estuary, a transgressive inner bay, Kikai-Akahoya volcanic ash, a deltaic inner bay, a tidal flat, and artificial soil. Changes in the depositional environment were mainly associated with sea-level rise after the end of the last glaciation. The reservoir ages of the eight pairs, 330 ± 70 yr, were obtained from a transgressive inner bay to deltaic inner bay sediments, formed during 4100–9200 cal BP. The chronological change in the reservoir effect allows us to correlate the Sukumo Core sediments with previous results from southwestern Japan, the Korean Peninsula, and Taiwan Island.

The Trondheim radiocarbon (14C) laboratory has evolved from a traditional radiocarbon decay counting laboratory to an accelerator mass spectrometry (AMS) facility primarily measuring 14C. This evolution required adjustments in sample preparation and data handling to match the capacity of the AMS system and reduction in sample sizes to about 1 mgC. We summarize here the steps involved in dating a sample at the National Laboratory for Age Determination in Trondheim, Norway. These include the structure of our sample database for information handling, sample cleaning procedures for different sample types, our reduction systems, both an automated EA-based system for regular use and a manual system for more challenging samples, and data evaluation. We will also briefly summarize the capabilities of our isotope-ratio mass spectrometer.

Methane contributes substantially to global warming as the second most important anthropogenic greenhouse gas. Radiocarbon (14C) measurements of atmospheric methane can be used as a source apportionment tool, as they allow distinction between thermogenic and biogenic methane sources. However, these measurements remain scarce due to labor-intensive methods required. A new setup for the preparation of atmospheric methane samples for radiocarbon analysis is presented. The system combines a methane preconcentration line with a preparative gas chromatography technique to isolate pure methane samples for a compound-specific radiocarbon analysis. In order to minimize sample preparation time, we designed a simplified preconcentration line for the extraction of methane from 50 L atmospheric air, which corresponds to 50 µg C as required for a reliable 14C analysis of methane-derived CO2 gas measurement with accelerator mass spectrometry (AMS). The system guarantees a quantitative extraction of methane from atmospheric air samples for 14C analysis, with a good repeatability and a low processing blank. The setup was originally designed for the measurement of samples with low methane concentrations, but it can also be adapted to apportion sources from environmental compartments with high methane levels such as freshwaters or wetlands.

The ENEA Radiocarbon Laboratory (Bologna, Italy) has been operating since 1985; it is the oldest among such laboratories operating in Italy and has been active for about 30 years in the field of dating of different types of samples with the radiocarbon (14C) liquid scintillation method. This study shows the detailed procedure for radiocarbon analysis on bioplastic materials by means of the synthesis of benzene, which includes CO2 production and purification, synthesis of acetylene, and synthesis and collection of benzene. The changes made to the original design of the synthesis procedures and the operational parameters adopted to optimize the combustion of the plastic materials are described. The measurement of 14C activity was performed using the liquid scintillation counting technique by a QuantulusTM 1220 low-background counter. The δ13C content was compared with the percentage of 14C concentration for the characterization of the bio content in plastic used in the food packaging.

Methane is the second most important anthropogenically produced greenhouse gas, and radiocarbon (14C) analysis is extremely valuable in identifying its age and source in the environment. At the NERC Radiocarbon Facility (East Kilbride, UK) we have developed expertise in analysis of methane 14C concentration and methodological approaches to field sampling over the past 20 years. This has opened a wide range of applications, which have mainly focused on (1) the age and source of methane emitted by peatlands and organic soils (e.g. to quantify the release of ancient carbon), (2) the source of aquatic emissions of methane, and (3) the age of methane generated by amenity and illegal landfill. Many of these scientifically important applications involve challenging sampling and measurement considerations, which our development program has continually aimed to overcome. Here, we describe our current methods, and recent improvements to aid field collection of samples in remote locations. We present the results of tests which (1) show the effectiveness of our methods to remove contaminants, especially CO2, (2) quantify the 14C background contribution, and (3) demonstrate the reliability of metal gas storage canisters for sample storage.

Despite many ideas about the age and processes of sand movements and paleosol formation, there are still some uncertainties in this relations in the Nyírség, eastern Hungary. The major aim of the present study was to clarify the chronology of fossil soils and blown-sand layers in the sand dunes of the Nyírség using radiocarbon (14C) dating on soil and charcoal samples. Charcoal and soil samples were collected from buried paleosols from different sand quarries for 14C dating. The bulk organic carbon content of the buried soil and charcoal pieces recovered from buried fossil soil layers allowed parallel 14C accelerator mass spectrometry dating in several cases. The new 14C results indicate paleosol development during Younger Dryas, while the preceding interstadial was assumed as a cold and dry period when only sand movement occurred in the area. Our results also confirm and support the previous assumptions, that in the Late Glacial, the first paleosol development period was during the Bølling-Allerød Interstadial. Four soil-forming periods could be determined during the Holocene (Preboreal, Boreal, Atlantic, Subatlantic). We have also indirectly identified sand movements during the Oldest Dryas, Younger Dryas, Preboreal, Boreal, and Subatlantic phase in the study area.