Tracing old carbon sources in Hungarian nectar samples using radiocarbon analysis Tamás Varga, Zsófi Sajtos, Botond Buró, Zsuzsa Lisztes-Szabó, István Futó, Mihály Molnár Scientific Reports, 2025 In our previous research, we observed a discrepancy between the apparent 14 C age of the carbon content of honey samples and their known age, date of the collection. The aforementioned studies demonstrated the existence of substantial old carbon intake, even older than five years, as evidenced by the outcomes of bomb-peak based radiocarbon dating. In order to ascertain the cause of the anomalies identified, a targeted nectar sample collection was conducted in Hungarian sampling areas. Consequently, the carbon isotope ratios ( 13 C/ 12 C and 14 C/ 12 C) of individual nectar samples from black locust, linden, phacelia, rapeseed and apple were determined by isotope ratio mass spectrometry (IRMS) and accelerator mass spectrometry (AMS). Furthermore, 14 CO₂ data from an international atmospheric background station were employed for comparative purposes. The presented results demonstrate that the aforementioned anomalies, previously detected in honey, can also be observed in nectar samples. It has been demonstrated that carbon deposits of up to three years old, and in some cases exceeding 60–70 years of age, can be identified in nectars. In addition to representing the first 14 C/ 12 C nectar results, the findings underscore the potential for older carbon stored in soil or plants to enter the food chain through nectar.
Investigating the impact of COVID-19 on the atmospheric 14C trend and fossil carbon load at urban and background sites in Hungary Balázs Áron Baráth, Tamás Varga, István Major, László Haszpra, Danny Vargas, Zoltán Barcza, Mihály Molnár Radiocarbon, 2025 The study analyses in situ CO2 mole fraction, 14CO2, and fossil based excess CO2 mole fraction (Cfoss) data at Hegyhátsál (HUN) rural monitoring station (Central Europe) supplemented by passive monitoring of 14C content of tree-rings. Through the observed period (2014–2020) we focused on revealing trends in atmospheric CO2 and 14C levels, particularly during the year of the first COVID lockdown, in comparison to the preceding five years. In addition, monthly integrated samples of atmospheric CO2 and tree-rings from the six years were subjected to 14C analysis. The passive tree-ring measurements focuses on two major urban areas (Budapest and Debrecen) in Hungary, along with the rural monitoring site. Results show a steady increase in CO2 levels at HUN between 2014 and 2020. The calculated fossil based excess CO2 concentrations for the initial year of COVID are in good agreement with the previous five-year averages both at 115 m and 10 m elevations. These results also show seasonal variations of CO2 mole fractions, peaking in winter and decreasing in summer. Tree-ring results from Debrecen show a good alignment with the results of the atmospheric monitoring station, and it does not show a significant fossil contribution in the urban background area during the vegetation periods. Tree-ring results from Budapest show a stronger fossil contribution compared to the Debrecen ones. Our atmospheric CO2 results do not show a large decrease in fossil CO2 atmospheric contribution during the first lockdown. We found that the use of this passive CO2 monitoring technique can provide a valuable tool for investigating such differences.
Novel dissolved organic14C analyses method applied in a case study at a LILW waste repository A Molnár, M Veres, T Varga, P Turza, A J T Jull, R Janovics, M Molnár Radiocarbon, 2025 A routine chemical procedure was developed at the Ede Hertelendi Laboratory of Environmental Studies (HEKAL), in Debrecen which can measure the dissolved organic radiocarbon content of groundwater as well as the inorganic and total fraction. The typical background of this non-purgeable dissolved organic radiocarbon preparation is 0.73 ± 0.14 percent modern carbon (pMC), using a carbon contamination correction on fossil dissolved material (potassium hydrogen phthalate) samples.
A laser-based saturated-absorption cavity ring-down technology for precise biobased content analysis of plastic samples Tamás Varga, Mihály Molnár, Luca Varricchio, Federico Carcione, Amelia Detti, Saverio Bartalini Journal of Cleaner Production, 2024 The integration of biobased materials into the plastics market is inevitable to meet European and global targets for carbon-neutral and sustainable production. To support the research, supply and production chains of bioplastics, independent analytical methods are needed to verify the biobased content of raw and final materials. In addition to the recently adopted accelerator mass spectrometry (AMS) method, we present a laser-based saturated-absorption cavity ring-down technology (SCAR) for accurate biobased content determination based on radiocarbon measurement. The traditional AMS method was compared with the state-of-the-art SCAR laser technology to verify the capability of the method. The method was successfully demonstrated to be capable of verifying the biobased content of plastic materials with an accuracy of <1% (absolute) over the entire range from fossil (0%) to fully biobased (100%). The applied measurement time of 50–60 min is comparable to AMS. No systematic offset or 14 C concentration-related shift was observed between the two methods, demonstrating that the SCAR method is reliable and can be adopted for research and industrial applications. The rapid, automated measurement protocol using an elemental analyzer makes the method suitable for high throughput applications. Dissemination of the cheaper laser-based technologies to biobased research and industry can help to speed up the integration of biomaterials into the market. • Commercial plastic samples were analysed for 14 C using a laser-based technique. • The results were compared with the standard Accelerator Mass Spectrometry method. • No significant offset and concentration dependent differences were observed. • The SCAR method was able to determine the 14 C/ 12 C ratio with an uncertainty of <1%. • The test results show that the SCAR 14 C method is mature for several applications.
The timing of the ca-660 BCE Miyake solar-proton event constrained to between 664 and 663 BCE Irina P. Panyushkina, A. J. Timothy Jull, Mihaly Molnár, Tamás Varga, Ivan Kontul’, Rashit Hantemirov, Vladymir Kukarskih, Igor Sljusarenko, Vladymir Myglan, Valerie Livina Communications Earth and Environment, 2024 Extreme solar energetic particle events, known as Miyake events, are rare phenomena observed by cosmogenic isotopes, with only six documented. The timing of the ca. 660 BCE Miyake event remains undefined until now. Here, we assign its occurrence to 664–663 BCE through new radiocarbon measurements in gymnosperm larch tree rings from arctic-alpine biomes (Yamal and Altai). Using a 22-box carbon cycle model and Bayesian statistics, we calculate the radiocarbon production rate during the event that is 3.2–4.8 times higher than the average solar modulation, and comparable to the 774–775 CE solar-proton event. The prolonged radiocarbon signature manifests a 12‰ rise over two years. The non-uniform signal in the tree rings is likely driven by the low rate of CO2 gas exchange between the trees and the ambient atmosphere, and the high residence time of radiocarbon in the post-event stratosphere. We caution about using the event’s pronounced signature for precise single-year-dating. 14 C signature in tree rings of northern Eurasia with double-pulse cosmic radiation signal and unusual cosmogenic isotope production suggests the Miyake event of 660 BCE occurred between 664–663 BCE, according to 14 C dispersion data with new time series of gymnosperm larch from arctic-alpine biomes.
Isotopic study of honey documents widespread plant uptake of old carbon in North America Tamás Varga, Zsófi Sajtos, Edina Baranyai, Zsuzsa Lisztes-Szabó, Ágota Ragyák, Mihály Molnár, A.J. Timothy Jull, Szilárd Szabó, Krisztina Hajduné Kosdi, István Futó, James M. Kaste Science of the Total Environment, 2024 A comprehensive understanding of carbon cycling pathways in the soil-plant system is needed to develop models that accurately predict global carbon reservoir responses to anthropogenic perturbations. Honey is a carbon-rich natural food produced by wild and managed pollinating insects all over the world; the composition of a single sample is a function of millions of pollinator-plant interactions. We studied the 13C/12C and Δ14C of 121 honey samples sourced from the United States, and found a significant older carbon contribution. The effect is observed from 25 to 45° latitude, not correlated with 13C/12C, and consistent with a previously published study on European honeys. In specific cases, the measured values were up to 20 ‰ (Δ14C) higher than the expected atmospheric 14CO2 value for the given year, which shows a significant older carbon contribution. We hypothesize that the older carbon is from plant liquids derived in part from soil carbon or stored nonstructural carbohydrates from plants, which shifts the calibrated age of the sample by 5 years or more. Our work is the first to describe the widespread occurrence of older carbon in honey and shows that radiocarbon measurements can be a powerful tool to trace carbon allocations in terrestrial food webs and detect the atmosphere-soil-plant carbon cycle contributions.
Characterisation of urban aerosol size distribution by radiocarbon and PIXE analyses in a middle-European urban environment for source identification: a pilot study Anikó Angyal, Zoltán Szoboszlai, István Major, Mihály Molnár, Tamás Varga, Zsófia Török, Enikő Papp, Furu Enikő, Maria Gini, Manousos Ioannis Manousakas, Zita Szikszai, Zsófia Kertész Environmental Science and Pollution Research, 2024 This study, conducted in Debrecen, Hungary, aimed to analyse atmospheric particulate matter (APM or PM) through radiocarbon and PIXE analyses during the winter smog (23–25 January) and spring (15–18 May) seasons. The information presented in this pilot study aims to provide insight into the importance of utilising detailed characteristics of the mass size distributions of fossil carbon (ff) and contemporary carbon (fC) content. Additionally, it seeks to compare these characteristics with the size distributions of various elements to enable even more accurate PM source identification. In winter, APM concentrations were 86.27 μg/m3 (total), 17.07 μg/m3 (fC) and 10.4 μg/m3 (ff). In spring, these values changed to 29.5 μg/m3, 2.64 μg/m3 and 7.01 μg/m3, respectively. Notably, differences in mass size distribution patterns were observed between the two seasons, suggesting varied sources for contemporary carbon. Biomass burning emerged as a crucial source during the smog period, supported by similar MMAD (Mass Median Aerodynamic Diameter) values and a strong correlation (r = 0.95, p < 0.01) between potassium and fC. In spring, a significant change in the concentration and distribution of fC occurred, with a broad, coarse mode and a less prominent accumulation mode. Ff was found to have similar distributions as PM, with nearly the same MMADs, during both periods. Finally, a comprehensive comparison of modal characteristics identified specific sources for the various components, including biomass burning, vehicle exhaust, coal and oil combustion, vehicle non-exhaust, road dust, tyre abrasion, mineral dust and biogenic emission. This study showcases how using radiocarbon and PIXE analysis in size distribution data can enhance our understanding of the sources of PM and their effects on different size fractions of PM.
Spring buds of European woody plants have old 14C age Tamás Varga, Dominik Nagy, Mihály Molnár, A.J. Timothy Jull, István Futó, Zsuzsa Lisztes-Szabó Heliyon, 2024 Trees and shrubs maintain carbon reserves to support their functions during periods when metabolic demand exceeds carbon supply, such as during the dormant season. To gain a better understanding of carbon storage and utilisation dynamics of eight woody plant species in temperate Central Europe, bud scale and leaf samples were collected to determine the radiocarbon age of fresh sprouts in trees and shrubs, at three background sites avoiding local emissions that may influence affect the observed 14 C/ 12 C ratio. The accelerator mass spectrometry-based bomb-radiocarbon approach, to determine the age of the mobilized carbon in the plant bud samples from storage, was complemented by stable carbon isotope measurements. The bomb-radiocarbon dating technique was used to determine the age of the samples, while a northern hemispheric atmosphere 14 CO 2 dataset was used to calibrate the radiocarbon ages of the plant samples. The youngest observed calibrated radiocarbon age of the buds was over 4 years, and the oldest was even 9 years old. There was no significant difference between the ages of bud scales and embryonal leaf laminas. Our results show that there is a considerable amount of stored older carbon in the woody stems that can be used to produce buds in spring, which is a complex mixture of stored carbon of different ages, but there is no relationship between the radiocarbon age and the stable carbon isotope composition. The observed results show that not only the tree species, but shrubs also can store and use significantly older carbon pools, the carbon storage intensity is similar for trees with trunks and short-stemmed shrubs branching directly above the ground, i.e. carbon storage starts in young twigs and continues in ageing branches.
AN INTERCOMPARISON PROJECT on 14C from SINGLE-YEAR TREE RINGS Sabrina G K Kudsk, Jesper Olsen, Gregory W L Hodgins, Mihály Molnár, Todd E Lange, Jessica A Nordby, A J Timothy Jull, Tamás Varga, Christoffer Karoff, Mads F Knudsen Radiocarbon, 2021
GAS ION SOURCE PERFORMANCE of the ENVIRONMICADAS at HEKAL LABORATORY, DEBRECEN, HUNGARY Mihály Molnár, Marianna Mészáros, Róbert Janovics, István Major, Katalin Hubay, Botond Buró, Tamás Varga, Titanilla Kertész, Virág Gergely, Ádám Vas, Gergely Orsovszki, Anita Molnár, Mihály Veres, Martin Seiler, Lukas Wacker, A J Timothy Jull Radiocarbon, 2021
CAN the 14C PRODUCTION in 1055 CE BE AFFECTED by SN1054? F Terrasi, F Marzaioli, R Buompane, I Passariello, G Porzio, M Capano, S Helama, M Oinonen, P Nöjd, J Uusitalo, A J T Jull, I P Panyushkina, C Baisan, M Molnar, T Varga, G Kovaltsov, S Poluianov, I Usoskin Radiocarbon, 2020
Comprehensive analysis of the elemental composition and isotope ratios of honeys from US East Coast ÁZ Ragyák, T Varga, NAK Ahmed, M Braun, A Horváth, Z Lisztes-Szabó, ... Food Chemistry, 149254 , 2026 2026
AMS-validated high-precision radiocarbon analysis of 14C-enriched environmental samples by laser spectroscopy T Varga, D Mazzotti, M Molnár, I Galli, L Varricchio, BÁ Baráth, KN Pap, ... Talanta, 129152 , 2025 2025
Tracing old carbon sources in Hungarian nectar samples using radiocarbon analysis T Varga, Z Sajtos, B Buró, Z Lisztes-Szabó, I Futó, M Molnár Scientific Reports 15 (1), 36704 , 2025 2025
Novel dissolved organic 14C analyses method applied in a case study at a LILW waste repository A Molnár, M Veres, T Varga, P Turza, AJT Jull, R Janovics, M Molnár Radiocarbon 67 (1), 74-87 , 2025 2025
A laser-based saturated-absorption cavity ring-down technology for precise biobased content analysis of plastic samples T Varga, M Molnar, L Varricchio, F Carcione, A Detti, S Bartalini Journal of Cleaner Production 483, 144319 , 2024 2024 Citations: 3
Isotopic study of honey documents widespread plant uptake of old carbon in North America T Varga, Z Sajtos, E Baranyai, Z Lisztes-Szabó, Á Ragyák, M Molnár, ... Science of the Total Environment 947, 174691 , 2024 2024 Citations: 2
The timing of the ca-660 BCE Miyake solar-proton event constrained to between 664 and 663 BCE IP Panyushkina, AJT Jull, M Molnár, T Varga, I Kontul’, R Hantemirov, ... Communications Earth & Environment 5 (1), 454 , 2024 2024 Citations: 8
Characterisation of urban aerosol size distribution by radiocarbon and PIXE analyses in a middle-European urban environment for source identification: a pilot study A Angyal, Z Szoboszlai, I Major, M Molnár, T Varga, Z Török, E Papp, ... Environmental Science and Pollution Research 31 (34), 47258-47274 , 2024 2024 Citations: 3
Spring buds of European woody plants have old 14C age T Varga, D Nagy, M Molnár, AJT Jull, I Futó, Z Lisztes-Szabó Heliyon 10 (12) , 2024 2024 Citations: 4
The potential of biogenic fraction analysis by radiocarbon in food, drug, and cosmetic products T Varga, D Szejke, Z Nemes, AJT Jull, M Molnár Radiocarbon 65 (5), 1176-1192 , 2023 2023 Citations: 2
Radiocarbon dating of microliter sized Hungarian Tokaj wine samples T Varga, M Molnár, A Molnár, AJT Jull, L Palcsu, E László Journal of Food Composition and Analysis 118, 105203 , 2023 2023 Citations: 7
Intercomparison exercise on fuel samples for determination of biocontent ratio by 14C accelerator mass spectrometry T Varga, I Hajdas, L Calcagnile, G Quarta, I Major, AJT Jull, A Molnár, ... Radiocarbon 65 (2), 539-548 , 2023 2023 Citations: 6
The IAEA forensics program: results of the AMS 14C intercomparison exercise on contemporary wines and coffees G Quarta, I Hajdas, M Molnár, T Varga, L Calcagnile, M D’Elia, A Molnar, ... Radiocarbon 64 (6), 1513-1524 , 2022 2022 Citations: 9
Scaling the 14C-excursion signal in multiple tree-ring series with dynamic time warping I Panyushkina, V Livina, M Molnár, T Varga, AJT Jull Radiocarbon 64 (6), 1587-1595 , 2022 2022 Citations: 6
The potential of radiocarbon analysis for the detection of art forgeries I Hajdas, L Calcagnile, M Molnár, T Varga, G Quarta Forensic Science International 335, 111292 , 2022 2022 Citations: 15
Detailed Carbon Isotope Study of PM 2.5 Aerosols at Urban Background, Suburban Background and Regional Background Sites in Hungary I Major, M Molnár, I Futó, V Gergely, S Bán, A Machon, I Salma, T Varga Atmosphere 13 (5), 716 , 2022 2022 Citations: 6
Rape, sunflower and forest honeys for long-term environmental monitoring: Presence of indicator elements and non-photosynthetic carbon in old Hungarian samples Z Sajtos, T Varga, Z Gajdos, P Burik, M Csontos, Z Lisztes-Szabó, AJT Jull, ... Science of the Total Environment 808, 152044 , 2022 2022 Citations: 16
Soil organic carbon dating of paleosoils of alluvial fans in a blown sand area (Nyírseg, Hungary) B Buró, G Négyesi, T Varga, G Sipos, D Filyó, AJT Jull, M Molnár Radiocarbon 64 (1), 1-19 , 2022 2022 Citations: 12
An intercomparison project on 14C from single-year tree rings SGK Kudsk, J Olsen, GWL Hodgins, M Molnár, TE Lange, JA Nordby, ... Radiocarbon 63 (5), 1445-1452 , 2021 2021 Citations: 5
Radiocarbon in the atmospheric gases and PM10 aerosol around the Paks Nuclear Power Plant, Hungary T Varga, I Major, V Gergely, A Lencsés, T Bujtás, AJT Jull, M Veres, ... Journal of environmental radioactivity 237, 106670 , 2021 2021 Citations: 4
MOST CITED SCHOLAR PUBLICATIONS
More rapid 14C excursions in the tree-ring record: a record of different kind of solar activity at about 800 BC? AJT Jull, I Panyushkina, F Miyake, K Masuda, T Nakamura, T Mitsutani, ... Radiocarbon 60 (4), 1237-1248 , 2018 2018 Citations: 47
Fossil fuel combustion, biomass burning and biogenic sources of fine carbonaceous aerosol in the Carpathian Basin I Salma, A Vasanits-Zsigrai, A Machon, T Varga, I Major, V Gergely, ... Atmospheric Chemistry and Physics 20 (7), 4295-4312 , 2020 2020 Citations: 44
Honey as an indicator of long-term environmental changes: MP-AES analysis coupled with 14C-based age determination of Hungarian honey samples T Varga, Z Sajtos, Z Gajdos, AJT Jull, M Molnár, E Baranyai Science of the Total Environment 736, 139686 , 2020 2020 Citations: 40
Source identification of PM2. 5 carbonaceous aerosol using combined carbon fraction, radiocarbon and stable carbon isotope analyses in Debrecen, Hungary I Major, E Furu, T Varga, A Horváth, I Futó, B Gyökös, G Somodi, ... Science of the Total Environment 782, 146520 , 2021 2021 Citations: 29
Can the 14C production in 1055 CE be affected by SN1054? F Terrasi, F Marzaioli, R Buompane, I Passariello, G Porzio, M Capano, ... Radiocarbon 62 (5), 1403-1418 , 2020 2020 Citations: 25
Advanced atmospheric 14C monitoring around the Paks nuclear power plant, Hungary T Varga, G Orsovszki, I Major, M Veres, T Bujtás, G Vegh, L Manga, ... Journal of environmental radioactivity 213, 106138 , 2020 2020 Citations: 23
Fossil carbon load in urban vegetation for Debrecen, Hungary T Varga, P Barnucz, I Major, Z Lisztes-Szabó, AJT Jull, E László, J Pénzes, ... Radiocarbon 61 (5), 1199-1210 , 2019 2019 Citations: 19
Rape, sunflower and forest honeys for long-term environmental monitoring: Presence of indicator elements and non-photosynthetic carbon in old Hungarian samples Z Sajtos, T Varga, Z Gajdos, P Burik, M Csontos, Z Lisztes-Szabó, AJT Jull, ... Science of the Total Environment 808, 152044 , 2022 2022 Citations: 16
The potential of radiocarbon analysis for the detection of art forgeries I Hajdas, L Calcagnile, M Molnár, T Varga, G Quarta Forensic Science International 335, 111292 , 2022 2022 Citations: 15
Identification of Potential Methane Source Regions in Europe Using δ 13 C CH4 Measurements and Trajectory Modeling T Varga, RE Fisher, JL France, L Haszpra, AJT Jull, D Lowry, I Major, ... Journal of Geophysical Research: Atmospheres 126 (17), e2020JD033963 , 2021 2021 Citations: 14
Gas ion source performance of the EnvironMICADAS at HEKAL Laboratory, Debrecen, Hungary M Molnár, M Mészáros, R Janovics, I Major, K Hubay, B Buró, T Varga, ... Radiocarbon 63 (2), 499-511 , 2021 2021 Citations: 14
Rapid 14 C excursion at 3372-3371 BCE not observed at two different locations AJ Timothy Jull, IP Panyushkina, M Molnár, T Varga, L Wacker, N Brehm, ... Nature Communications 12 (1), 712 , 2021 2021 Citations: 13
High-precision biogenic fraction analyses of liquid fuels by 14C AMS at HEKAL T Varga, I Major, R Janovics, J Kurucz, M Veres, AJT Jull, M Péter, ... Radiocarbon 60 (5), 1317-1325 , 2018 2018 Citations: 13
Soil organic carbon dating of paleosoils of alluvial fans in a blown sand area (Nyírseg, Hungary) B Buró, G Négyesi, T Varga, G Sipos, D Filyó, AJT Jull, M Molnár Radiocarbon 64 (1), 1-19 , 2022 2022 Citations: 12
Spatial distribution of 14C in tree leaves from Bali, Indonesia T Varga, AJT Jull, Z Lisztes-Szabó, M Molnár Radiocarbon 62 (1), 235-242 , 2020 2020 Citations: 12
The IAEA forensics program: results of the AMS 14C intercomparison exercise on contemporary wines and coffees G Quarta, I Hajdas, M Molnár, T Varga, L Calcagnile, M D’Elia, A Molnar, ... Radiocarbon 64 (6), 1513-1524 , 2022 2022 Citations: 9
The timing of the ca-660 BCE Miyake solar-proton event constrained to between 664 and 663 BCE IP Panyushkina, AJT Jull, M Molnár, T Varga, I Kontul’, R Hantemirov, ... Communications Earth & Environment 5 (1), 454 , 2024 2024 Citations: 8
Radiocarbon dating of microliter sized Hungarian Tokaj wine samples T Varga, M Molnár, A Molnár, AJT Jull, L Palcsu, E László Journal of Food Composition and Analysis 118, 105203 , 2023 2023 Citations: 7
Variation of 14C in Japanese tree rings related to the Fukushima nuclear accident T Varga, L Palcsu, T Ohta, Y Mahara, AJT Jull, M Molnár Radiocarbon 61 (4), 1029-1040 , 2019 2019 Citations: 7
Intercomparison exercise on fuel samples for determination of biocontent ratio by 14C accelerator mass spectrometry T Varga, I Hajdas, L Calcagnile, G Quarta, I Major, AJT Jull, A Molnár, ... Radiocarbon 65 (2), 539-548 , 2023 2023 Citations: 6
