This work aims to clarify the absolute chronology of the construction phases of the St. Peter and Paul Rotunda at Budeč, focusing on the erection of the rotunda and the tower. Fifteen mortar samples were taken from various structural parts, two of which also contained remnants of charcoal. The mortar samples were mechanically treated to extract a purified calcitic binder that was dated by radiocarbon analysis. The effectiveness of the sample pretreatment methodology was assessed by means of cathodoluminescence microscopy. Thin sections of mortars were characterized by polarized light microscopy. The petrographic characterization allowed for the samples to be grouped according to their binder, aggregate, and structure. This was compared with the evaluation of the calibrated dates, expected chronology known from legends, as well as with formal and stylistic analyses of the structure. The radiocarbon dating distinguished the different construction phases well, and the accuracy and reliability of the dating is discussed. The presence of silts and clays probably led to geogenic carbon contamination of the samples from the foundations, as the obtained dates are older than expected. These dating results were thus regarded as inconclusive. However, the samples from the vaulted dome of the rotunda did not show any anomalies, and the calibrated date period obtained was regarded as relevant and thus successfully dated. The dating based on the legends also fits the determined interval.

Tree-ring cellulose is a commonly used material for radiocarbon analysis. Extracting cellulose is labor-consuming and several devices that enable batchwise extraction have been developed. However, these devices bear the risk of sample contamination. The present study describes a new device which improves upon two aspects of currently available devices. First, to prevent cross-sample-contamination, we redesigned the drainage module to enable independent removal of chemical waste from each individual sample funnel. Second, we added covers to the sample funnels to reduce the risk of external contamination. Cellulose purity (i.e., holocellulose) was confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. Furthermore, accuracy of the radiocarbon analysis was confirmed by results of 14C-blank samples and samples of known age. In conclusion, while maintaining labor-saving, our modified device significantly reduces the risk of sample contamination during extraction of tree-ring cellulose.

One century after its initial excavation, this article presents the first absolute chronology for the settlement of Karanis in Egypt. Radiocarbon dates from crops retrieved from settlement structures suggest that the site was inhabited beyond the middle of the fifth century AD, the time at which it was previously believed to have been abandoned. These dates add to the complex picture of population fluctuations and the remodelling and reuse of structures at Karanis. Two dates reach into the middle of the seventh century, placing the abandonment of the site in a period of political and environmental transition that changed the physical and social landscape of the Fayum region and beyond.

The Rio Grande Cone is a major fanlike depositional feature in the continental slope of the Pelotas Basin, Southern Brazil. Two representative sediment cores collected in the Cone area were retrieved using a piston core device. In this work, the organic matter (OM) in the sediments was characterized for a continental vs. marine origin using chemical proxies to help constrain the origin of gas in hydrates. The main contribution of OM was from marine organic carbon based on the stable carbon isotope (δ13C-org) and total organic carbon/total nitrogen ratio (TOC:TN) analyses. In addition, the 14C data showed important information about the origin of the OM and we suggest some factors that could modify the original organic matter and therefore mask the “real” 14C ages: (1) biological activity that could modify the carbon isotopic composition of bulk terrestrial organic matter values, (2) the existence of younger sediments from mass wasting deposits unconformably overlying older sediments, and (3) the deep-sediment-sourced methane contribution due to the input of “old” (>50 ka) organic compounds from migrating fluids.

A new radiocarbon preparation facility was set up in 2010 at the Godwin Laboratory for Palaeoclimate Research, at the University of Cambridge. Samples are graphitized via hydrogen reduction on an iron powder catalyst before being sent to the Chrono Centre, Belfast, or the Australian National University for accelerator mass spectrometry (AMS) analysis. The experimental setup and procedure have recently been developed to investigate the potential for running small samples of foraminiferal carbonate. By analyzing background values of samples ranging from 0.04 to 0.6 mg C along with similar sized secondary standards, the setup and experimental procedures were optimized for small samples. “Background” modern 14C contamination has been minimized through careful selection of iron powder, and graphitization has been optimized through the use of “small volume” reactors, allowing samples containing as little as 0.08 mg C to be graphitized and accurately dated. Graphitization efficiency/fractionation is found not to be the main limitation on the analysis of samples smaller than 0.07 mg C, which rather depends primarily on AMS ion beam optics, suggesting further improvements in small sample analysis might yet be achieved with our methodology.