Annually resolved radiocarbon (14C) records from tree rings provide a high-resolution archive for investigating short-term atmospheric 14C variations driven by solar and cosmic activity, as well as terrestrial processes, including geomagnetic modulation, stratosphere–troposphere exchange, ocean–atmosphere interactions, and tree physiological traits. While extensive data are available for the Northern Hemisphere, comparable high-resolution records from the Southern Hemisphere are scarce, making it difficult to obtain robust 14C calibration for the south and to evaluate 14C distribution models. Here, within the framework of the CHASCA project, we present a new annually resolved 14C record from Fitzroya cupressoides, a long-lived conifer native to southern South America, spanning AD 970–1084 (RAL060), with samples collected in North Patagonia, Argentina. This is the first annually resolved radiocarbon series from South America and among the longest for the Southern Hemisphere.

The CHASCA series shows strong agreement with Northern Hemisphere datasets and with SHCal20 confirming the expected interhemispheric offset. It also captures the AD 993–994 solar particle event, with a statistically significant level (≈ 7 σ), though with reduced amplitude compared to the shorter decade-long records from New Zealand and Chile. This attenuation may reflect a combination of stratospheric–tropospheric dynamics, regional environmental conditions, and species-specific growth dynamics, although these mechanisms remain speculative and require further investigation, underscoring the complexity of local expression of cosmogenic 14C signals. The CHASCA series thus extends the geographic coverage of annually resolved-14C datasets and establishes South America as a key region for detecting and comparing short-term cosmogenic events.

Extreme solar particle events (ESPEs) are caused by rare, enormously strong solar eruptions and can produce globally detectable spikes in tree-ring radiocarbon 14C, known as Miyake events, which serve as precise chronological tie-points and indicators of extreme solar activity. After production, radiocarbon is subjected to the complex carbon cycle, including large-scale atmospheric transport, which is crucially important for fast and strong Miyake events with highly inhomogeneous 14C production. A new 3D dynamical model, SOCOL:14C-Ex, of the radiocarbon atmospheric production and transport is presented here, which can model fast changes in the 14C atmospheric concentrations with high temporal and spatial resolution. Precise response curves of Δ14C to a reference ESPE (100×GLE#69) were computed for various event dates. They can be directly applied to analyze Miyake events under different conditions. Seven strong events over the past 14 millennia (AD 993, AD 774, 664 BC, 5260 BC, 5411 BC, 7177 BC, and 12,351 BC) were analyzed by fitting the reference curves to the available annual Δ14C data, identifying the most probable values and confidence intervals of their parameters—strength, event’s date and background level. By applying corrections for the geomagnetic and atmospheric (CO2) factors, the strengths of the corresponding ESPEs were assessed. The strongest ESPE is confirmed to be that of 12,351 BC, while that of AD 774 remains the strongest event during the Holocene. To conclude, a new tool, based on the radiocarbon atmospheric transport model SOCOL:14C-Ex, is presented to analyze fast changes in the 14C production.

Here we present an updated version of radiocarbon concentrations measured in seeds from the Gatersleben Crop Plant Research institute. 14C-isotope measurements for wheat from 1946 to 2020, which were presented previously, have been complemented with 14C measurements made on soybean and continued until late summer 2025. Additionally, we measured δ13C in wheat samples.

A comparison of different 14C time series over the last 80 years from different regions such as the Colorado Plateau (herbaria archived annual plants; Carbone et al. 2023), England (Barley; Dunbar et al. 2024), and Germany (Gatersleben seed, this study) reveal 14C discrepancies during peak bomb-period with reference atmospheric 14C data, i.e., the Northern Hemisphere Zone 1 & 2, and may indicate a heterogenous atmospheric 14C composition, i.e., admixture of different air masses with a slightly divergent 14C composition.

The Yucatán Peninsula, Mexico, has many shallow coastal lagoons. The interest in the study of mangroves and other ecosystems in this area is due to their capacity to store large amounts of organic carbon (blue carbon). To understand this process, sediments can provide information about the evolution over time of the coastal zone, through changes in their physical and chemical composition.

Isotopic techniques have proven to be useful in the study of different coastal processes such as carbon sequestration rates and other events. However, coastal ecosystems are dynamic regions that change over time, representing a challenge for dating with nuclides such as 14C. Previous studies have focused on the dating of fractions of different sizes or fractions in which the carbon comes from different sources. These strategies help to find the most probable date of deposition of the sediments.

In this study we dated 14C paleosol sediment fractions obtained from mangrove-dominated areas that have undergone a transformation process. We dated different fractions such as macrofossils, total organic matter, humin, and humic acids, from sediment cores collected from two paleosol sites with different geological and hydrological characteristics: Jaina in Campeche and Ría Lagartos in Yucatán, Mexico. In both cores we observed that in the absence of macrofossils, the fractions that indicate the best age to report are total organic matter or humin.

The analysis and interpretation of radiocarbon dates can involve many steps, such as switching between units or time-scales, assessing the impacts of contamination, applying marine or other offsets, inspecting calibration curves, calibrating dates, extracting probabilities from calibrated distributions, and analysing and plotting multiple dates. Here, we present rice, a new open-source R package which, together with other packages such as rbacon, Bchron, coffee and clam, enables users to perform such calculations within R, thus allowing most of the steps from data entry to calibration, age-modeling and subsequent analysis and interpretation of time-series to be performed within a single widely-used, multi-platform, transparent and open-source software environment. All calculation steps are documented and can be inspected, and users can also write new/enhanced functions. The package could thus prove useful in both educational and research settings.

This study examines Neltuma pallida wood from the Cerro Laguna archaeological site in coastal Peru to establish a floating chronology and absolute dating. Ten cross-sections yielded a 70-year chronology (CLAA1). Alpha-cellulose was extracted from five single growth rings from one sample for radiocarbon dating, then wiggle-matching in OxCal v4.4 using SHCal20. Results place the youngest ring at 1314–1330 CE (95.4% probability), situating the full sequence in the period between 1253 and 1322 (±8) CE. Statistical analyses show a robust dendrochronological signal, and ring-width data suggest strong El Niño Southern Oscillation (ENSO) events around 1300 CE. These findings confirm Cerro Laguna’s Late Intermediate Period occupation and allow us to assume that the entire 70-year period can be used to improve the calibration curve for the Southern Hemisphere.

The accuracy and precision of radiocarbon dating largely depend on the quality of sample preparation prior to measurement. Proper selection of material, identification of potential contaminants, and application of appropriate purification procedures are the basis of reliable 14C analyses. Modern preparation laboratories not only support the process of obtaining reliable results but also play a key role in integrating the scientific community and educating future geochronologists. In 2025, a new Laboratory of Preparation for Radiocarbon Dating (LBC14) was established at Maria Curie-Skłodowska University in Lublin, Poland. The laboratory has been adapted for the selection and purification of macroscopic organic samples, such as charcoal, wood, peat, organic sediments, macrofossils, and bone—both unburned and cremated. The protocols used are acid-base-acid (ABA), ultrafiltration, and apatite preparation, modified according to the material’s state of preservation. The paper presents the scope of the new laboratory, the procedures used, and the first results of dating performed at the AMS Laboratory at ETH Zurich. The presented initiative is an important step towards the development of 14C research infrastructure in Poland and the construction of sustainable, interdisciplinary standards for working with dating material.

This study employs radiocarbon measurements (Δ14C) to detect fossil fuel CO2 (CO2ff) in the megacity Delhi from 2018 to 2022, offering unique insights into fossil fuel emissions. Our measurements reveal varying Δ14C values ranging from −56.2‰ to 7.5‰ and CO2ff values ranging from 0.3 ppm to 25.2 ppm. We observed a distinct seasonality in Δ14C and CO2ff, with higher CO2ff (lower Δ14C) values during winter and post-monsoon seasons and lower CO2ff (higher Δ14C) in summer and monsoon seasons. We have determined emission ratios (RCO and RNOx), and compared them with other studies worldwide. Our study also examines the impact of the COVID-19 lockdown periods on CO2ff and observed a notable decrease of 5.6 (4.8) ppm during the pandemic’s first (second) waves. These findings enhance our understanding of CO2 emission inventories in megacity Delhi.

The radiocarbon content of dissolved inorganic carbon (DIC: CO2(aq), HCO3–, CO32–) and gaseous CO2 can provide valuable information for the cycling and residence time of carbon in groundwaters, porewaters, hydrocarbon reservoirs, methane seeps, and hydrothermal systems. Fluids and gases from these systems often contain high concentrations of hydrogen sulfide (H2S) that interferes with critical steps of the analytical procedure, particularly the reduction of CO2 to graphite. We developed and tested a simple and effective method to remove H2S from water and gas samples prior to graphitization by passing the gas through a silver nitrate solution in dilute nitric acid. The resulting cleaned CO2 was sufficiently pure to be reduced to graphite by hydrogen on an iron catalyst. The mass of the process blank of this method is negligible (0.45 ± 0.10 µg C, with F14C of 0.30 ± 0.20) and almost identical to our process blanks without the H2S trap (0.43 ± 0.10 µg C, F14C = 0.30 ± 0.10). The method has been successfully applied to samples containing elevated H2S from multiple hydrothermal vent fluids.

La Marmotta is one of the best-preserved Early Neolithic lakeshore settlements in the Mediterranean, yet its chronology has remained poorly defined. Previous interpretations relied mainly on decoration-based ceramic classifications and a limited radiocarbon dataset, hindering our understanding of the site’s occupational dynamics and its role in the wider European Neolithic. This study presents a revised chronological framework grounded in 35 radiocarbon determinations, including 22 new dates on short-lived botanical remains and selected wooden artifacts. The samples were carefully selected from well-documented contexts to minimise post-depositional disturbance and analyzed using Bayesian modeling. Radiocarbon results were interpreted in parallel with a detailed reassessment of ceramic artifacts and decorations. This integrated approach suggests that ceramic variability does not reflect a succession of different phases, but rather the cultural diversity of a single, dynamic community.

Stable carbon and oxygen isotopes in carbonate nodules were controlled by the type of vegetation (C3 or C4) and soil temperature, respectively. These signatures can reflect the paleoclimatic conditions during the formation of the carbonate nodules. Carbonate nodules were sampled along a soil chronosequence in southwestern Taiwan, representing different ages of shoreline changes associated with phases of marine transgression and regression. The stable carbon and oxygen isotopes in carbonate nodules were analyzed. The ages of the carbonate nodules were determined by radiocarbon (14C) dating. The climofunctions of mean annual precipitation and temperature were calculated to interpret the climatic conditions. The carbonate nodules were relictic pedofeatures that formed episodically under favorable pedogenic conditions between 4063 and 690 years before present (years BP). The δ13C values indicated a mixed vegetation of C3 and C4 plants, with a predominance of C4 plants (68.0 to 98%). The mean annual temperature estimated by the climofunction of δ18O value (12.3 to 14 °C) was lower than the present (24.7 °C). The mean annual precipitation (1036 to 1342 mm yr–1) calculated by the geochemical climofunction was lower than the present (1829 mm yr–1). The climate was drier and cooler during this period, and this may be due to a weaker East Asian Summer Monsoon, which favored calcification in the soils. The climatic conditions, as interpreted by the stable carbon and oxygen isotopes of carbonate nodules, were consistent with the calcification process.

The radiocarbon (14C) composition of dissolved organic carbon (DOC) provides critical constraints on its sources, transformation and fates. UV-irradiation is an effective approach to completely oxidize DOC to CO2 for radiocarbon measurements. In this study, we aimed to evaluate the performance of radiocarbon measurements for small/ultra-small size natural DOC samples using mini carbon dating system (MICADAS) using CO2 gas as the target. The procedure blank was estimated by the indirect method using two reference standards, oxalic acid II (OXII, modern) and glycine (dead). We modified the UV-generated CO2 purification and collection approaches for freshwater and marine samples based on the sample salinity. The results showed that the procedure blanks were low and statistically identical for the two approaches, with the carbon mass of 1.65 ± 0.50 µgC and the F14C value of 0.4848 ± 0.1455 for freshwater sample processing, and 1.70 ± 0.51 µgC with F14C value of 0.4118 ± 0.1235 for marine sample. The UV-generated CO2 gases in small/ultra-small size (30 – 126 µgC) DOC samples from the Pearl River-Estuary-northern South China Sea continuum were further measured and the data correction was based on those corresponding procedure blank. Our results were comparable to previous studies obtained with large sample size and graphite target for radiocarbon measurements. We concluded that the UV-oxidation system combined with MICADAS gaseous CO2 measurements at OUC is particularly suitable for small/ultra-small size DOC samples with high throughput, and this system provided powerful tools to acquire radiocarbon data to understand the compositional, spatial and temporal variabilities of DOC.

Oil contamination in estuarine and coastal ecosystems presents major challenges for environmental monitoring due to the complex mixture of organic matter from biogenic and petrogenic sources. This review synthesizes recent advances and limitations in the combined use of carbon isotopes δ13C and Δ14C to trace petroleum contamination in marine sediments. Sixteen empirical studies were analyzed to evaluate the effectiveness of this dual-isotope approach in identifying fossil carbon, estimating its degradation state, and assessing its environmental persistence. While δ13C provides insights into organic matter sources and transformation, Δ14C offers a sensitive tracer for detecting fossil carbon inputs, even in low concentrations or mixed matrices. The review highlights how their integration strengthens source attribution and enhances the resolution of hydrocarbon monitoring in dynamic coastal settings. An exploratory typology based on Δ14C and Fm is proposed to semi-quantitatively classify contamination severity and support cross-study comparisons. Despite its potential, the approach faces challenges such as high analytical costs, limited laboratory access, and a lack of methodological standardization. Future efforts should focus on integrating compound-specific isotope analysis, expanding applications in mangrove ecosystems, and refining interpretative models to improve the forensic utility of carbon isotopes in oil spill investigations. This review contributes to the systematization of isotopic methods in environmental forensics and reinforces their role in tracing petroleum-derived carbon in sensitive coastal environments.

The Holocene clastic and organic sediments from the La Falda section (northern Puna, Argentina), covering the late Northgrippian to early Meghalayan periods, were analyzed. These sediments contain abundant plant macrofossils and microfossils, including leaves and stems attributed to Cyperaceae and Poaceae, as well as pollen. Charcoal is also present in significant amounts. The analysis of these remains provides insights into past environmental and climatic conditions. Our results suggest that palaeoenvironmental and palaeoclimatic changes during this period were relatively minor, with a clear trend of geomorphological stability. Geochronological data, based on 15 radiocarbon dates, confirm through a depth-age model that no major erosion or accumulation events occurred between 4750 and 3450 cal BP.

The Fuji River flows approximately 128 km from north to south near the center of the Japanese archipelago, with its mouth located near the collision boundary between the Eurasian Plate and the Philippine Sea Plate. To investigate the Holocene activity of an onshore subduction thrust at the northern end of the Nankai Trough, we measured radiocarbon ages of terrestrial plants and marine shells in sediments collected from across the Fuji River. Ten sediment cores, Ng-1 to 4, Km-1 to 5, and Nz-1, were obtained from an uplifted terrace to a subsidence lowland along the border of Suruga Bay. Based on analyses of lithology, molluscan assemblages, and radiocarbon dating, the cores were classified into six sedimentary facies. In ascending order, they are river channel, floodplain, estuary, estuary front, inner bay, and lagoon. These paleoenvironmental changes are primarily associated with sea-level fluctuations and tectonic movements during the post-deglacial period. The terrestrial accumulation curve aligns with the horizons of Kawago-daira pumice and Kikai-Akahoya volcanic ash. Reservoir ages of six pairs from the estuary to inner bay facies of the Ng1 core ranged from 150 ± 70 to 470 ± 60, during the period from 7900 to 6800 cal BP, and their average was calculated to be 310 ± 120 years. The chronological changes in the reservoir effect can be correlated with Holocene sediments from the coastal area of Southwest Japan under the influence of the Kuroshio warm current.

The chronology of Late Glacial and Early Holocene dune formation and wildfire activity at the Łaskarzew site, eastern Poland, was reconstructed using a combination of accelerator mass spectrometry (AMS) radiocarbon dating (14C) and optically stimulated luminescence (OSL) dating. The stratigraphic profile records 13 aeolian-soil cycles, characterized by alternating phases of aeolian deposition, soil formation, and wildfire episodes, reflecting the interplay between short-term climatic oscillations and aeolian processes. Radiocarbon dates were obtained from 26 charcoal samples embedded within palaeosols and charcoal horizons and calibrated using the IntCal20 curve, while OSL dating of quartz grains provided additional chronological control for aeolian sediments. The integration of these two dating methods established a robust timeline of environmental changes. The aeolian activity began during the Oldest Dryas and intensified during the Allerød interstadial, with four distinct wildfire events associated with rapid vegetation recovery and fire-prone landscapes. The Younger Dryas was marked by widespread aeolian deposition under arid climatic conditions, with no organic layers preserved. In the Holocene, nine independent wildfire episodes spanning approximately 4500 years were identified, linked to warm climatic conditions and the dominance of pine forests. Aeolian activity persisted into the Middle Holocene, accumulating nearly three meters of sediment before stabilizing around 7 ka BP due to increased vegetation cover. This study underscores the effectiveness of integrating radiocarbon and luminescence dating to resolve Late Quaternary chronologies, providing insights into fire-vegetation dynamics and aeolian processes within the European Sand Belt.

River deltas play a crucial role in the global carbon cycle, acting both as significant carbon sinks and as sources of CO₂ to the atmosphere. The Rhône River delta is a key site for studying these processes due to its high sedimentation rates and its unique radiocarbon signatures influenced by anthropogenic activities. This study compiles over 10 years of research to assess the sources and fate of organic matter (OM) in the Rhône River delta, using stable (δ13C) and radiogenic (Δ14C) carbon isotopes. New data from the MissRhoDia II campaign (2018) are compared with previous datasets (CarboRhone 2012; DICASE 2014) to analyze the interactions between terrestrial, riverine, and marine OM sources. The study examines sedimentary processes along a transect from the river mouth to the continental shelf, considering both sediment burial and porewater analyses. Results indicate that OM mineralized in proximal sediments is primarily of terrestrial origin, freshly supplied by the river, and potentially influenced by nuclear-related activity. In contrast, on the continental shelf, remineralization occurs at a slower rate due to the limited availability of organic substrate and isotopic signatures reveal a predominantly marine origin with a minimal anthropogenic influence. In the Rhône pro-delta sediments, the burial of radiocarbon-free organic carbon (aOC) underscores the role of sediment transport in long-term carbon storage, with contributions from both petrogenic and aged terrestrial organic carbon sources. The mineralization of young, labile carbon and the burial of more refractory carbon create significant differences between the 14C signatures measured in porewaters and sediments, highlighting the need to analyze both compartments. This study improves our understanding of carbon dynamics in the Rhône delta and provides valuable perspectives to better understand coastal carbon budgets, carbon sources, as well as the anthropogenic influence on marine ecosystems.

This paper presents new radiocarbon (14C) measurements from annual tree rings of English oak (Quercus robur L.) from Kujawy, Poland, spanning 1042–1062 CE. The results confirm an increase in Δ14C values between 1053 and 1055 CE, within the Oort Minimum of solar activity, consistent with literature values (Brehm et al. 2021a; Eastoe et al. 2019; Terrasi et al. 2020). The data reveal a sustained increase in Δ14C values between 1053 and 1055 CE, rising from −6.9 ± 1.8‰ to −2.6 ± 1.8‰. For the preceding period (1042–1052 CE), the average Δ14C value is −11.0 ± 1.9%, indicating a significant increase of 8.4 ± 2.6‰ toward 1055 CE. The study estimates the 14C production rate during this period and suggests the radiocarbon increase likely began before 1054 CE, indicating it is unlikely to be significantly attributed to the supernova in 1054 CE. The study contributes to refining the understanding of rapid changes in atmospheric radiocarbon and their potential causes.

At ANSTO, we have developed an automated dissolved inorganic carbon (DIC) processing line, known as A-DIC, designed to sequentially process 10 water samples for radiocarbon analysis without any operator intervention. The A-DIC works at ambient pressure using helium (He) gas as a carrier. It includes a water pump capable of drawing adjustable sample volumes between 22-180 mL into a 250 mL reaction vessel. Upon the addition of 5 mL of phosphoric acid to the vessel, the sample is sparged with helium (He) gas at a rate of 45 mL/min for 16 min. The desorbed CO2 from the sample is then carried along with He through a series of traps: water vapor traps at –75 °C, a sulphur (SOx) trap containing silver wires at 650 °C, and two CO2 traps at –196 °C. The A-DIC is automated via a Python script executed on a PC connected via USB. It demonstrates consistent performance and CO2 trapping efficiency across batches of up to 10 samples. For contamination study, the CO2 gas collected is transferred to graphitization units to be converted into graphite for AMS analysis.