Rýzmburk Castle is one of the largest and most important medieval castles in Bohemia, documented since 1250 AD. Its North tower is assumed to be built in 1260–1300 AD. To test this assumption, the surface layers of mortar were inspected for the presence of charcoals suitable for radiocarbon dating, and 10 charcoals were found. The charcoals probably originated from wood used for lime burning. The results of radiocarbon dating using accelerator mass spectrometry agree with the historical estimation. Single post-1287 sample indicates that the building date might be refined to 1287–1300 AD.

The method of determining the biobased carbon content in liquid fuel samples is standardized, but different laboratories use different protocols during sample preparation and perform the measurements using different machines. The accelerator mass spectrometry (AMS) laboratories use different combustion, preparation, and graphitization methods for the graphite production for the spectrometric measurements. As a result, the intercomparison between the laboratories is inevitable to prove precision and accuracy and to demonstrate that the results are comparable. In this study, we present the results of an intercomparison campaign involving three 14C accelerator mass spectrometry laboratories. Five samples were used in the measurement campaign, including two biocomponents (fatty acid methyl ester, hydrotreated vegetable oil), one fossil component (fossil diesel), and two blends (mixtures of fossil and biocomponent with 90–10% mixing ratio) in the laboratories of CEDAD (Italy), ETH (Switzerland), and INTERACT (Hungary). The results presented by the laboratories are comparable, and all three laboratories could determine the biobased carbon content of the samples within 1% relative uncertainty, which is acceptable in the scientific, economic, and industrial fields for biocomponent determination.

This study applied, radiocarbon dating to charcoal and mollusk samples from Sernambetiba and Amourins archaeological sites in the Northeast region of Guanabara Bay, in the state of Rio de Janeiro, Brazil, to assess the marine radiocarbon reservoir effect (MRE) of this area, being applied for the correction of the marine samples ages. The results for this estuarine system were ΔR = –87 ± 90 14C yr and ΔR = –244 ± 70 14C yr for 3970 ± 70 14C yr BP and 2357 ± 60 14C yr BP, respectively. Based on these findings, calibrated 14C ages were calculated for Sernambetiba and Amourins shell mound sites surrounding the bay. Marine samples from the Guapi site were analyzed and only their radiocarbon ages presented because there were no paired terrestrial samples for the MRE assessment. These results are coherent with previously published values also derived from archaeological samples for the Rio de Janeiro state coastal region and contribute to the interpretation of human occupation of the region during the Holocene.

Paradigms such as the coexistence of incineration and inhumation funerary practices in the northeast of the Iberian Peninsula during the Late Bronze Age are supported by the association of human remains with elements of material culture as guiding fossils. One example is the association established by Salvador Vilaseca in 1939 between the human remains and grooved pottery discovered in the Cova de Marcó in Tivissa (Ribera d’Ebre, Catalonia). This association has been accepted until today and even become a paradigm for the mixing of autochthonism (inhumation rites) with the introduction of material novelties such as grooved pottery and incineration rites during the first period of the Late Bronze Age. Direct radiocarbon (14C) dating of human remains from the Cova de Marcó shows that the remains originate from the Chalcolithic period. This indicates that there is no relationship between the sepulchral episode and the grooved pottery associated with it and used to date it. This disputes the paradigm regarding the coexistence of these two funerary practices during the Late Bronze Age and invites scholars to conduct a critical review using absolute dating techniques directly on the human remains of similar cases in order to verify or disprove the paradigm’s validity.

A MIni CArbon DAting System (MICADAS) has been recently installed at the Ocean University of China (OUC) mainly for determining the radiocarbon (14C) ages for marine sedimentary organic carbon. In this study, we compared the data from a series of CO2 samples measured independently by the MICADAS at OUC and ETH Zurich to assess whether the data from the OUC MICADAS meet our requirement for carbon cycle research. The measured samples covered a range of 14C ages from 1229 to 12,287 yr, and size from 5 to 162 µg C. The data from the two instruments showed a good linear relationship with only small 14C age offsets, meeting our research demands such as carbon source apportionment. Lastly, we propose that for MICADAS clients, such a cross-lab comparison of the size- and age-dependency of MICADAS using age-known samples is important for 14C data integration.

Tree-ring series offer considerable potential for the development of environment-sensitive proxy records. However, with traditional increment cores, only small amounts of wood are often available from annual tree-ring sequences. For this reason, it is important to understand the reliability (and reproducibility) of radiocarbon measurements obtained from small-sized samples. Here we report the F14C results from the Chronos 14Carbon-Cycle Facility of modern tropical Australian tree samples over a range of four graphite target sizes from the same rings. Our study shows that similar precision can be obtained from full-sized, half-sized, as well as small-sized graphite targets using standard pretreatment and analysis procedures. However, with a decline in sample size, there was an increase seen in the associated variance of the ages and the smallest target weights started showing a systematic bias. Wiggle-matching accuracy tests, comparing the Southern Hemisphere post-bomb atmospheric calibration curve to the different sample weight sequences, were all significant except for the 200 μgC graphite targets. Our results indicate that samples smaller than 350 μgC have limited accuracy and precision. Overall, reliable measurements of F14C sequences from tree-ring records across a range of sample sizes, with best results found using graphitized samples >350 μgC.

The Single Stage AMS radiocarbon facility at the Australian National University has operated for the past 14 years. This paper presents the pretreatment methods used for the major sample types dated and reflects on whether quality assurance protocols can adequately detect altered materials. The majority of fossil samples dated by the facility are from tropical and arid environments where diagenesis of both organic samples and carbonates is often severe. A large proportion of the samples submitted cannot be dated, and screening and quality assurance methods are crucial. Based on analysis of 250 measurements on bone collagen, quality assurance indicators for bone are revised. From May 2021, the laboratory has accepted dates on collagen where yield >0.5%, %C is in the range of 39.7–46.9, and the C:N ratio is between 3.00 and 3.30.