This brief review describes the discovery of cosmic rays by Victor Hess from the Vienna Radium Institute and the later contribution of Marietta Blau through her observation of “disintegration stars” in photographic emulsion plates exposed to cosmic-ray bombardment. Marietta Blau, a nearly forgotten cosmic-ray pioneer from the Vienna Radium Institute, developed the nuclear emulsion technique for studying nuclear reactions, eventually discovering the disintegration of nuclei through high-energy cosmic rays. Blau survived the Holocaust by escaping to Mexico City from 1939 to 1944. Starting in 1948 at Columbia University, later as a staff member of Brookhaven National Laboratory and then University of Miami, she performed fundamental and original research with nuclear emulsions exposed to 3-GeV protons at the Brookhaven Cosmotron and to 6-GeV protons at the Berkeley Bevatron. Blau returned to Vienna in 1960, where at the Radium Institute a classical β-decay counting facility for radiocarbon dating had been installed, which was finally superseded by the Vienna Environmental Research Accelerator (VERA), a modern versatile accelerator mass spectrometry facility.

In Brazil, laws are being adopted prohibiting the use and distribution of non-recyclable plastic bags and encouraging the use of recyclable, biodegradable and bioplastic bags. However, there is no specific standard method in Brazil to inspect the carbon content of bioplastics. This work aims to implement the sample preparation for radiocarbon biogenic fraction determination in bioplastics in the new radiocarbon laboratory at the Federal University of Bahia (LAPA14C-UFBA). Six plastic samples from Brazilian markets with bio-based seals were collected in regular Brazilian markets, four bags and two tubes. All samples were combusted and graphitized in the LAPA14C-UFBA and the graphites were measured at the Radiocarbon Laboratory (LAC-UFF). The biogenic fraction analysis followed the Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis (ASTM D6866-24). Since the bioplastic manufactured in Brazil is derived from sugarcane, a C4 plant where δ13C values are different from those of petroleum-derived plastic, the biogenic fraction was obtained via the isotopic mixture equation. The results showed a robust direct correlation (r=0.998) between the fractions obtained by the two methods, indicating that δ13C analysis can be used, in this case, as an alternative in determining the biogenic fraction of plastics. From the results obtained, four out of the six samples analyzed showed biogenic fraction values below the 51% required by the I’m Green label, with values ranging from 4% to 43%, according to the δ3C and 14C analysis, showing the efficiency of both techniques in determining the biogenic fraction.

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.

Cosmogenic 7Be and 10Be are effective tracers for studying atmospheric dynamics and Earth’s surface processes, with over 90% of these isotopes reaching the surface via wet deposition. However, the characteristics and influencing factors of 7Be and 10Be wet deposition remain unclear in different regions, limiting the precision of these nuclides as tracers of environmental change. This study analyzes the annual variation of 7Be and 10Be wet deposition in Xi’an and examines the impact of precipitation on their deposition. Ultra-trace levels of 7Be and 10Be in precipitation were synchronously measured using state-of-the-art accelerator mass spectrometry. One-year (July 30, 2020 to September 3, 2021), high-frequency (individual rain events) and time-synchronized series of observations of 7Be and 10Be wet deposition data (n = 49) were analyzed. The total annual wet deposition fluxes of 7Be and 10Be in central China (34.22°N, 109.01°E) for 2020/21 were (218 ± 24) × 108 atoms·m–2·yr–1 and (314 ± 16) × 108 atoms·m–2·yr–1, respectively. Precipitation amount, intensity, and duration were quantitatively analyzed for their effects on total wet deposition flux, mean concentration, washout ratio, deposition velocity, and scavenging coefficient of 7Be and 10Be during individual rain events. The results indicate that precipitation amount is the most significant factor influencing the wet deposition flux of both nuclides.

Carbon occurs as organic and inorganic matter in numerous complex forms and mixtures. Thermal separation of sample mixtures (e.g. sediment or soil), coupled with radiocarbon analysis, is a valuable approach for investigating the source, residence time, or age of different carbon components. At the NEIF Radiocarbon Laboratory we have built equipment for thermally separating samples for radiocarbon analysis using ramped oxidation. The original instrumentation has been successfully tested and validated for the purpose of partitioning samples based on their temperature of thermal decomposition, and for reliable radiocarbon measurement of different sample components. However, the original configuration of our instrument has limitations; a single analysis takes 2–3 hours, and an operator must be present to manually isolate samples from the required temperature ranges. To address this, we have upgraded our ramped oxidation equipment to include computer-controlled solenoid valves. These are activated according to a user-defined sampling scheme which enables autonomous collection of thermally partitioned samples. Here, we describe the latest improvements and present thermograms showing compatibility with the previous version of our equipment. This includes measurements of the radiocarbon background of the equipment, and results for known 14C-content radiocarbon standards. These demonstrate the reliability of the new configuration of our equipment for radiocarbon measurements.

Between 2021 and 2023, the Center for Applied Isotope Studies (CAIS) tested over 500 samples for biobased carbon content under the United States Department of Agriculture’s (USDA) Biopreferred Program using the American Society for Testing and Materials (ASTM) biobased testing standard D6866. We describe some of the novel approaches we used to prepare a diverse array of biobased products and summarize those radiocarbon test results and success rates in meeting the USDA Minimum Biobased Content (MBC).

In freshwater samples, benzalkonium chloride (BAC) effectively prevents radiocarbon (14C) of dissolved inorganic carbon (DIC) from changing owing to its bactericidal effects. The addition of BAC is a promising alternative method to mercury, which is currently the standard method of sterilization. Therefore, it is important to investigate its basic potential in advance for radiocarbon observations in seawater if mercury is prohibited. Since the BAC efficiency decreases in seawater, our investigation focused on salinity, which is the distinguishing characteristic of seawater. The disinfectant effects of BAC in the low- and high-salinity (4.4 and 26.5) seawater samples at a constant BAC concentration and the varying BAC concentrations at a constant salinity (20.8) were examined. With BAC treatment, the higher-salinity samples exhibited larger changes in DIC 14C concentration and δ13C value, indicators of microbial activity, than the lower-salinity samples. At higher BAC concentrations (0.1% or 1%), DIC isotope values changed negligibly over time, whereas at the lower concentration (0.01%) they changed significantly over time. These findings suggest that salt diminishes the efficiency of BAC, potentially by degrading it, thereby reducing its bactericidal activity and allowing microorganism populations to recover, thus altering 14C concentration. Further, they indicate that increasing the BAC dosage may overcome its diminished efficacy in seawater samples.

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.

Radiocarbon dating is a widely used method in archaeology and earth sciences, but the precision of calibrated dates from single radiocarbon measurements can be difficult to understand. This study investigates the precision of calibrated radiocarbon dates depending on the uncertainties of the measurement and the details of the calibration curve. Using data for the Holocene epoch and the IntCal20 calibration curve, over 1,000,000 hypothetical radiocarbon measurements were calibrated and analyzed. The study shows that high-precision measurements can yield calibrated date ranges from less than 50 years to more than 200 years (at the 95.4% probability) depending on the specifics of the calibration curve. This research may serve as a tool for planning future studies and assessing whether high-precision measurements are beneficial for proposed case.

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.

A database of ca. 970 radiocarbon dates on bones, teeth, and tusks of the woolly mammoth (Mammuthus primigenius Blum.) from Siberia was created in order to understand the spatiotemporal distribution of this species over the last 50,000 14C years (BP). Mammoths populated all parts of Siberia until ca. 12,000 BP. After that, a few refugia exited south of ca. 60°N at ca. 10,600–12,000 BP, and in the northern part of mainland Siberia mammoths survived until ca. 9700 BP. At ca. 9500–3700 BP, they existed only in today’s insular regions such as the New Siberian Islands and Wrangel Island in the High Arctic. The relationship between the dynamics of mammoth populations and climatic fluctuations is complicated. In the warmer intervals (interstadials), the number of mammoths in Siberia was generally slightly larger than in the colder times (stadials); however, the difference is often not significant. The connection between the dynamics of mammoth populations and climatic fluctuations in Siberia is therefore complicated and non-linear.

Using calibrated radiocarbon dates, this study investigates climate signals recorded in fluvial sedimentary archives from southern Poland, eastern Netherlands, and eastern Germany. Summed probability density functions (PDFs) were constructed and analyzed in the context of INTIMATE stratigraphy. The results indicate that fluvial sedimentation and erosion processes were closely linked to climate fluctuations, particularly during GS/GI and GI/GS transitions. The analyses indicate multi-scale relationships between regional geomorphological processes and global climate trends during the period from 50 to 15 cal kBP. This study provides a reconstruction of Late Pleistocene fluvial activity and highlights the need for more precise radiocarbon dates to refine correlations between regional and global climate events.

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.