The quantification of fossil-fuel derived carbon dioxide (CO2ff) emissions is critical for regional carbon budgets. Radiocarbon (14C) is an effective tool to estimate the contribution of CO2ff to the total atmospheric CO2. In the present study, we have determined the spatial distribution of fossil fuel derived CO2 across Delhi using 14C measurements in Peepal tree leaves from April 2016 to March 2017 at city scale. Our analysis results show that the Δ14C values vary between –67.78‰ to 5.61‰ and corresponding CO2ff values are varying from 1.63 ppm to 33.34 ppm. CO2ff values from campus sites vary between 6.99 ppm to 16.38 ppm with an average value of 10.22 ± 3.20 ppm, while CO2ff values vary from 2.41 ppm to 33.34 ppm with an average value of 13.32 ± 9.40 ppm for sites located in the parks. Further, we observed the higher contributions of fossil fuels in the CO2 from northwest Delhi, central Delhi, and some parts of east and southwest Delhi. In the absence of real-time CO2 monitoring, the results of this study provide a potential method for analyzing the contribution of CO2ff values over the urban landscape to total CO2 over the study region.

In this contribution to our periodic ‘Archaeological Futures’ series, Lindsay M. Montgomery and Tiffany C. Fryer reflect on the reshaping of archaeological praxis in the Americas through recent developments in collaborative community-engaged research. Over the past 20 years, new theoretical and methodological approaches informed by decolonisation and Black feminism have shifted power dynamics within the discipline. The authors review this growing body of research, highlighting trends in collaborative archaeological research and discussing some of the ongoing challenges and tensions. They argue that this collaborative paradigm marks a new future for archaeology in the Americas, which will increasingly centre on topics of importance to Black and Indigenous scholars and descendant communities.

The timeframes of Holocene anthropogenic dune remobilization in Central Europe remain less studied compared to those of Late Glacial climatically controlled dune formation. The present contribution aims to reinforce existing knowledge on the chronology of Late Glacial–Holocene dune activity and stability, as well as to reveal the scale of human impact on dune remobilization. Accelerator mass spectrometry radiocarbon (AMS 14C) dating and calibration of the results are reported from paleosol horizons buried in inland dune deposits that occur in Central and Eastern Poland. Twenty-three new dates are based on charcoal samples collected at 13 sites. From each of the investigated sites, at least one AD date is obtained, indicating that buried paleosols of such young age are far more widespread in Polish dunes than reflected in previous studies. The widespread preservation of these paleosols under cover of aeolian sand reflects the extent of the anthropogenic dune formation phase that peaked during the Medieval and Early Modern periods.

The Marine20 radiocarbon (14C) age calibration curve, and all earlier marine 14C calibration curves from the IntCal group, must be used extremely cautiously for the calibration of marine 14C samples from polar regions (outside ∼ 40ºS–40ºN) during glacial periods. Calibrating polar 14C marine samples from glacial periods against any Marine calibration curve (Marine20 or any earlier product) using an estimate of ${\rm{\Delta R}}$, the regional 14C depletion adjustment, that has been obtained from samples in the recent (non-glacial) past is likely to lead to bias and overconfidence in the calibrated age. We propose an approach to calibration that aims to address this by accounting for the possibility of additional, localized, glacial 14C depletion in polar oceans. We suggest, for a specific polar location, bounds on the value of ${\rm{\Delta }}{{\rm{R}}_{20}}\left( {\rm{\theta }} \right)$ during a glacial period. The lower bound ${\rm{\Delta R}}_{20}^{{\rm{Hol}}}$ may be based on 14C samples from the recent non-glacial (Holocene) past and corresponds to a low-depletion glacial scenario. The upper bound, ${\rm{\Delta R}}_{20}^{{\rm{GS}}}$, representing a high-depletion scenario is found by increasing ${\rm{\Delta R}}_{20}^{{\rm{Hol}}}$ according to the latitude of the 14C sample to be calibrated. The suggested increases to obtain ${\rm{\Delta R}}_{20}^{{\rm{GS}}}$ are based upon simulations of the Hamburg Large Scale Geostrophic Ocean General Circulation Model (LSG OGCM). Calibrating against the Marine20 curve using the upper and lower ${\rm{\Delta }}{{\rm{R}}_{20}}$ bounds provide estimates of calibrated ages for glacial 14C samples in high- and low-depletion scenarios which should bracket the true calendar age of the sample. In some circumstances, users may be able to determine which depletion scenario is more appropriate using independent paleoclimatic or proxy evidence.

This article examines a group of five surviving twelfth- and thirteenth-century wax seal impressions from the British Isles that depict a scene of an armed knight in combat with a lion. This seal motif has tenuously been linked with crusading in the past, and so this paper seeks to address the connections between the sigillants and crusade, as well as the significance of commemoration of crusade culture on medieval seals. It highlights numerous links between this specific design and crusading experiences, literature and allegory. This paper focuses on an aspect of the medieval memory of crusade and the means of displaying chivalric, crusading identities within literate culture (on charters and letters) and in personal adornment.

The Laboratoire des Sciences du Climat et de l’Environnement (LSCE) has operated a radiocarbon dating laboratory for almost 70 years. It has evolved from a traditional ß-decay counting to an accelerator mass spectrometry facility. In 2015, the LSCE received a major upgrade with the installation of a MICADAS. This evolution required adjustments in sample preparation to match the new capability to date samples as small as a few tens of µgC. We summarize here the sample cleaning procedures and the chemical purification or extraction treatment that we apply to the samples. We also report values of blank and reference materials of different matrices that match the large diversity of samples handled at LSCE.

Atmospheric CO2 samples have been collected by the Trondheim Radiocarbon Laboratory since the 1960s. The remaining material from the measurements has been precipitated as CaCO3 and stored in glass containers. We investigated some of the stored samples to assess whether the material could still be used for remeasurements of atmospheric radiocarbon (14C) content, or if it has been contaminated during the years of storage. We attempted different methods to clean the carbonate and release the CO2 for new measurements. The results indicate that the older samples before 1970 show a significant change in 14C content compared to the original measurements, and that our cleaning methods have only little effect. Later samples from the 1970s, which were archived in glass containers with a different lid, show a lower contamination that, however, still leads to an added uncertainty of several pMC and makes these samples unreliable.

The IntCal family of radiocarbon (14C) calibration curves is based on research spanning more than three decades. The IntCal group have collated the 14C and calendar age data (mostly derived from primary publications with other types of data and meta-data) and, since 2010, made them available for other sorts of analysis through an open-access database. This has ensured transparency in terms of the data used in the construction of the ratified calibration curves. As the IntCal database expands, work is underway to facilitate best practice for new data submissions, make more of the associated metadata available in a structured form, and help those wishing to process the data with programming languages such as R, Python, and MATLAB. The data and metadata are complex because of the range of different types of archives. A restructured interface, based on the “IntChron” open-access data model, includes tools which allow the data to be plotted and compared without the need for export. The intention is to include complementary information which can be used alongside the main 14C series to provide new insights into the global carbon cycle, as well as facilitating access to the data for other research applications. Overall, this work aims to streamline the generation of new calibration curves.

We present the results of a multifaceted study of an antiphonary—liturgical song book—presumably made in Venice in 1607, now in the Ringve, National Music Museum of Norway in Trondheim1. The book is hand-sewn on raised cords, bound in full leather on cardboard covers, originally with metal clamps. The paper block consists of pages printed in black and red that include both song texts and music scores. The red ink is based on vermillion and red lead while the black ink is carbon based. The treads and cords were made of flax. The leather used was made from goat skin. Radiocarbon results confirmed the printing date. The antiphonary shows several signs of repair including the possibility of re-binding. Animal-based glue was used for the repairs as well as for the sizing of both original and repair paper. Two potential periods were identified for reparations, 1670–1710 AD and 1782–1830 AD. This case study was conducted prior to the opening of a new permanent exhibition, Soundtracks, at the Ringve Museum where the book is displayed.

Nitra-Lupka is an important site from the Great Moravian period in Slovakia. A fortified hillfort which was supposed to be from this period, a battery of pottery kilns, and an Early Medieval cemetery were found on the site and researched during 1959–1975. Further, a few small-range excavations took place on the site at the beginning of the 21st century. At the same time, the dating of the hillfort to the Early Medieval period has begun to be questioned. There was also a problem with the localization of settlement that would belong to the battery of pottery kilns. The settlement was discovered recently in 2021 during development-led excavations at Nitra-Šindolka. It was found at the place of the construction of the ecoduct. Two ovens and four other features with numerous ceramics and other findings were discovered. Some of the bones (phalanges of cattle and goat/sheep) were dated by radiocarbon dating being the first 14C data obtained from this site and therefore of high importance for its precise dating.

Short-term fluctuations in atmospheric radiocarbon (14C) concentration mark the tree-ring record for the last ∼15 kyr. Terrestrial macrofossils from sediment cores of Lake Suigetsu, Japan, extend this record of fluctuations back to >35 cal ka BP. Their significance, however, is under debate since the signal-to-noise ratio of the Suigetsu record is low and progressively decreases with increasing age. Coherent semi-millennial-scale structures of the Suigetsu 14C record have nevertheless been identified by three different techniques, namely visual inspection, analyses of the first derivative of 14C vs. calendar age, and Bayesian spline inflections of 14C concentration vs. calendar age, and hence appear objectively real. These 14C fluctuations correlate closely with those of the tree-ring-based 14C master record ∼10–14 cal ka. Thus, Suigetsu fine structures attain global significance and may properly reflect atmospheric 14C variability back to ∼35 cal ka. Carbonate-based 14C records from speleothems and ocean sediments are far smoother and form, together with Suigetsu and other data, the backbone of the IntCal20 record >14 cal ka that largely lacks the Suigetsu fine structure. 14C decay reduces 14C-signal amplitudes over time, so Holocene-style 14C signals of solar modulation disappear in the noise beyond ∼10 cal ka. The remaining older 14C fine structures had larger forcings, most likely linked to climate and carbon cycle, especially ocean-atmosphere CO2 exchange, and thus contain valuable information about these factors. They may also provide global stratigraphic tie points to correlate 14C records of oceanic plankton sediments and climate signals independent of problems with local 14C reservoir effects.

Compared with nitrogen and argon, helium is lighter and can better reduce the beam loss caused by angular scattering during beam transmission. The molecular dissociation cross-section in helium is high and stable at low energies, which makes helium the prevalent stripping gas in low-energy accelerator mass spectrometry (AMS). To study the stripping behavior of 14C ions in helium at low energies, the charge state distributions of carbon ion beams with −1, +1, +2, +3, and +4 charge states were measured at energies of 70–220 keV with a compact 14C-AMS at Guangxi Normal University (GXNU). The experimental data were used to analyze the stripping characteristics of C-He in the energy range of 70–220 keV, and new charge state yields and exchange cross-sections in C-He were obtained at energies of 70–220 keV.

In two forensic cases, radiocarbon (14C) bomb-pulse datings of human bones have been performed and analyzed using detailed models to correct for collagen-carbon turnover rates and reservoir effects. The modeled corrections are discussed and the resulting 14C ages compared to later information on actual time of birth and death of the individuals. Simple time lag corrections of bone dates are found to be inadequate, whereas modeling based on age dependent turnover rates and bomb-pulse levels through life combined with substantial reservoir age corrections can explain the observed 14C results.

Dating organic inclusions in mortars such as charcoals is a useful alternative or complementary method to dating mortars themselves, helping to estimate the building age. To assess the limitations of this dating approach, organic inclusions were searched for in surface mortar layers of six early to late medieval buildings in the Czech Republic with relatively well-known age. Altogether, 123 samples were found. About 80% were successfully radiocarbon (14C) dated. However, only 66% originated from wood relatively young when used in lime burning. To judge which samples are relevant to the actual building date, sufficient statistics is crucial. We recommend dating at least 5–10 samples, i.e., collecting 6–12 samples, for a site with uncomplicated building history, or per building phase. Otherwise, unrealistically old or young dates might be obtained. With the recommended statistics, inclusion-based dating provides building ages with uncertainty of 50–100 years.