By the 4th century CE, the territory of post-Roman Dacia constituted the western frontier of the Sântana de Mureș-Chernyakhov culture’s expansion. In this study, we analysed 26 individuals of the culture’s eponymous cemetery in the Carpathians at Sântana de Mureș. Radiocarbon modeling implies that the cemetery might have been established a few years after the Roman Empire’s retreat and was probably used only for a few decades at most. In the meantime, we could not identify the founding generation or any subsequent large-scale mobility within the community. Irrespective of regions, a harsh lifestyle might have characterized the studied individuals, who were probably affected by chronic and epigenetic diseases, strenuous physical exertion and poor overall health conditions. Inadequate intake of nutrients may also have contributed to a difficult lifestyle because access to terrestrial animal protein was modest while millet consumption uniformly dominated over other cereals. In contrast to the lifestyle of the previous provincial society, this type of diet might have been inherited from the predecessor Wielbark culture and most closely resembles that of other contemporary tribal communities, such as the Sarmatians in the Carpathian Basin.

The transition from MIS3 interstadial to the coldest stadial of the last glacial (MIS 2) marked a rapid change in the climate. Findings of multiproxy (sedimentological, MS, geochemical (AAS, XRD), micromorphological, anthracological, phytolith and malacological) studies from a loess/paleosol sequence in northeastern Hungary highlighted the transformation of a reddish-brown fossil soil layer (cambisol) to a podzolic soil with signs of iterative wildfires during the terminal part of MIS3. According to our findings, a Scots pine (Pinus sylvestris) dominated open parkland emerged on the northern slopes during the second phase of MIS3 hosted by a special reddish-brown soil. Then the last phase of MIS3 was marked by the development of spruce (Picea abies) dominated open parkland. Results further suggest that vegetation change passed a critical threshold leading to an unusually rapid expansion of spruce (within ca. 100 yr). This rapid expansion of spruce, changing the geochemistry of the litter to a more acidic state likely caused the initiation of podzolization and the transformation of the original soil. The opening of MIS2 marked not only intensive dust accumulation but also a steady decline of arboreal elements as well, leading to the emergence of a cold tundra on top of the podosol with charcoal remains.

The long-term relationship between climate change, vegetation change and soil development, is a highly complex process. Findings of multiproxy (sedimentological, MS, geochemical (AAS, XRD), micromorphological, anthracological, phytolith and malacological) studies from a loess/paleosol sequence in northeastern Hungary highlighted the transformation of a reddish-brown fossil soil layer (cambisol) to a podzolic soil with signs of iterative wildfires during the terminal part of MIS3. According to our findings, a Scots pine (Pinus sylvestris) dominated open parkland emerged on the northern slopes during the second phase of MIS3 hosted by a special reddish-brown soil. Then the last phase of MIS3 was marked by the development of spruce (Picea) dominated open parkland. Results further suggest that vegetation change passed a critical threshold leading to an unusually rapid expansion of spruce (within ca. 100 yr). This rapid expansion of spruce, changing the geochemistry of the litter to a more acidic state likely caused the initiation of podzolization and the transformation of the original soil. The opening of MIS2 marked not only intensive dust accumulation but a steady decline of arboreal elements as well leading to the emergence of a cold tundra on top of the podosol with charcoal remains.

Lake Balaton, the largest shallow lake in Central Europe, is highly sensitive to evaporation–inflow balance and provides an important archive of Holocene hydroclimate change. We reconstructed Holocene lake-level and moisture-availability changes using a high-resolution multi-proxy sediment record integrating age-modelled sediment stratigraphy, micro-XRF geochemistry, stable isotopes (δ13C, δ18O), grain size, XRD mineralogy and nanoscale TEM characterization of carbonate phases to identify the climatic drivers of hydrological change. Two major evaporative phases at ∼8050–7350 and ∼5450–4500 cal yr BP are marked by elevated Mg/Ca ratios and synchronous δ13C and δ18O maxima, indicating strongly reduced inflow, enhanced evaporation and substantially lower lake levels. The earlier interval represents the strongest evaporative phase in the record and followed the 8.2 ka event. The later interval reflects fluctuating hydrological conditions and alternating low- and high-stand phases during the onset of Neoglacial cooling. The first evaporative event coincided with post-8.2 ka summer warming linked to reinvigoration of the Atlantic Meridional Overturning Circulation (AMOC), whereas the second corresponded to widespread mid-Holocene hydroclimatic instability across Europe and the Mediterranean. This event was followed by the deepest lake phase between 4500 and 1900 cal yr BP. Our results demonstrate that Lake Balaton sensitively recorded both North Atlantic and Mediterranean hydroclimate forcings and provide new evidence for prolonged post-8.2 ka summer drought and mid-Holocene hydrological instability in Central Europe.

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 Delta 14C 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 Delta 14C values between 1053 and 1055 CE, rising from -6.9 +/- 1.8 parts per thousand to -2.6 +/- 1.8 parts per thousand. For the preceding period (1042-1052 CE), the average Delta 14C value is -11.0 +/- 1.9%, indicating a significant increase of 8.4 +/- 2.6 parts per thousand 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.

Urban areas are global hotspots of anthropogenic greenhouse gas emissions; however, distinguishing between fossil fuel combustion and biogenic fluxes remains challenging due to the complexity of the urban environment. High-precision atmospheric observations are essential for validating "bottom-up" emission inventories and guiding local green strategies. This study presents a comprehensive comparative analysis examining atmospheric CO2 and CH4 mole fractions, as well as atmospheric radiocarbon (14C) signals, from May 2025 in Debrecen (an urban environment) and two elevations at the regional background station in Hegyhátsál (ICOS HUN).During the research campaign, Picarro Cavity Ring-Down Spectroscopy (CRDS) analyzers were employed at both sites for continuous, high-resolution measurement of CO2 and CH4 concentrations. These measurements were complemented by a two-week integrated 14CO2 sampling, followed by Accelerator Mass Spectrometry (LEA-AMS) analysis. This dual-tracer approach enables the separation of the Debrecen CO2excess into fossil and biogenic components.Our results highlight that the urban-derived excess varies dynamically relative to the regional background. The continuous mole fraction data reveal characteristic diurnal and seasonal patterns, with wintertime enrichment of CO2 and CH4, driven by reduced boundary layer mixing and increased heating demand. Analysis of CH4:CO2 correlations provides further insight into sector-specific emissions, distinguishing between traffic-dominated and heating-dominated periods. By combining high-frequency concentration measurements with isotopic constraints, our study provides a more precise understanding of the urban carbon cycle in a mid-sized city in Hungary, highlighting the importance of parallel urban-rural monitoring networks in verifying climate protection measures.

To investigate the environmental history of the Tisza River (Hungary), we applied 14 C and OSL dating methods for five parallel, neighboring cores from the flood plain area (Jászság Basin). Four major sedimentary layers were identified: meadow soil on the top (S1); silty-clay (S2); clayey-silt (S3) section; and fine sand (S4). 14 C and OSL data were integrated into a synthetic age-depth model using the BACON software package. Formation of the S1 layer (depth: 0–1.0 m) falls in the Holocene, up to 10 kyrs cal BP, with moderate sedimentation rate (100 yr/cm aAR). The S2 layer (1.0–8.0 m depth) represent the entire Last Glacial to Upper Pleniglacial period (19–27 kyrs cal BP), with a much faster sedimentation (20 yr/cm aAr). The S3 section (8.0–17.0 m) represents a longer period (27–45 kyrs cal BP) with similar sedimentation rate (19 yr/cm aAr) as S2. These clayey silt layers fall into the Late Pleistocene/Middle Pleniglacial period, a period of nearly 18 kyrs of sedimentation resulting ∼9 m thick sediment. Our study delivered some new and important details about the surface evolution of the investigated Tiszasüly area. A missing part of about 10 kyrs period (between 10–19 kyrs cal BP) was revealed in the investigated synthetic cores.

Several short-term climate anomalies occurred during the Holocene, of which the 8.2 k.y. event was the most pronounced. Several proxy records ranging from the North Atlantic to monsoonal regions indicate that this event had a semi-global impact. The release of large amounts of freshwater into the North Atlantic has been cited as a major cause of the slowing of oceanic thermohaline circulation (von Grafenstein et al., 1998; Barber et al., 1999), resulting in this climate perturbation. Despite the significance of this event, high-resolution speleothem records are relatively scarce (e.g. Duan et al., 2023; Wood et al., 2023). These high-resolution oxygen isotope records from eastern China to South America revealed the complex structure of the 8.2 ky event.Here we present two high-resolution oxygen isotope records from Central Europe (Béke Cave, NE Hungary and Vacska Cave N Hungary), along with the chemical data of calcite and the hydrogen isotope composition of inclusion-hosted water. The high-resolution oxygen isotope time series reveals a double negative anomaly around 8.2 k.y., whereas a positive anomaly appears in the following period (8.1 k.y.). Similar patterns are also observed in the hydrogen isotope data series. Assuming that the temperature change was solely responsible for the observed systematics, this data is utilized to calculate the relative temperature increase/decrease. Apparently, a 1-1.5°C temperature decrease for the 8.2 k.y. event and a 2°C increase for the “overshoot” around 8.1 k.y. can be given. Moreover, the oxygen isotope composition may be affected not only by temperature but also by changes in the amount of precipitation and/or its seasonality, as well as by the shifting of the main route of moisture transportation (Atlantic vs. Mediterranean moisture sources). Calculated d-excess values might indicate some changes during these periods. Additionally, trace element composition suggests a shift in summer/winter precipitation amounts for the overshoot.We are thankful for the support and permission of the Aggtelek National Park Directorate and the Duna-Ipoly National Park Directorate. The János Bolyai Research Scholarship of the Hungarian Academy of Sciences financially supported György Czuppon’s work.Barber D.C, Dyke A., Hillaire-Marcel C., Jennings A. E., Andrews J. T., Kerwin M. W., Bilodeau G., McNeely R., Southon J., Morehead M. D., Gagnon J.-M. (1999) Forcing of the cold event of 8,200 years ago by catastrophic drainage of Laurentide lakes. Nature, 400, 344-348.Duan, P., Li, H., Ma, Z., Zhao, J., Dong, X., Sinha, A., et al. (2023). Interdecadal to centennial climate variability surrounding the 8.2 ka event in North China revealed through an annually resolved speleothem record from Beijing. Geophysical Research Letters, 50(1), e2022GL101182.von Grafenstein U., Erlenkeuser H., Müller J., Jouzel J. Johnsen S. (1998): The cold event 8200 years ago documented in oxygen isotope records of precipitation in Europe and Greenland. Climate Dynamics 14 : 73—81.Wood, C. T., Johnson, K. R., Lewis, L. E., Wright, K., Wang, J. K., Borsato, A., et al. (2023). High-resolution, multiproxy speleothem record of the 8.2 ka event from Mainland Southeast Asia. Paleoceanography and Paleoclimatology, 38, e2023PA004675.

The presence of cosmogenic radionuclide concentrations inherited from previous exposure(s) of glacially transported boulders and moulded bedrock surfaces may hinder the determination of the surface exposure age (SED) of the last phase of (de)glaciation. A previous study revealed that glacial landforms of the cirque area in the southern side of the Retezat Mountains (Southern Carpathians, Romania) hold significant amount inherited 10Be (t1/2=1.4 My), which was used for a tentative estimation of the amount of glacial erosion, assuming that the lowest 10Be concentration was representative of the true age of deglaciation (Ruszkiczay-Rüdiger et al., 2021, Geomorphology 384, 107719). In this study, a western valley, the Zlătuia-Dobrunu valley of the Retezat Mts was sampled for 10Be SED. The novel data are in agreement with the previous datasets suggesting that the most extended glaciers belonged to the Last Glacial Maximum. However, the old apparent exposure durations based on 10Be analysis of samples from the cirque area provided firm evidence for the presence of excessive abundances of cosmogenic 10Be in this valley as well. The use of the short-lived in situ produced 14C (t1/2= 5.7 ky) provides an independent age constraint for the timing of the last deglaciation, because all 14C inventories that might be inherited from a previous exposure would have already been decayed. As a consequence, the 14C concentrations are not biased by inheritance, thus i) enable the age determination of the landforms belonging to the last phases of deglaciation and ii) the 14C exposure ages compared to the 10Be data will allow an assessment of the inherited amount of 10Be and thus a more precise determination of the amount of glacial erosion. In this study the new 10Be and 14C SED ages will be presented together with the mapped glacial landforms, reconstructed paleoglaciers and their Equilibrium Line Altitudes. Funding: NKFIH FK124807, INSU/CNRS, ANR - “EQUIPEX Investissement d’Avenir”, IRD and CEA, the PNRR-III-C9-2022 - I8, no. 760055/23.05.2023, CF 253/29.11.2022. and Horizon 2020 grant 871149 ”EUROPLANET”.

This section summarizes the use of accelerator mass spectrometry (AMS) for radiocarbon dating measurements. It expands on the principles already laid out in the sections on "Principles of Radiocarbon Dating" and "Conventional Radiocarbon Dating." The great advantage of AMS is that it allows dating of very small, sub-milligram (<0.5 mg C) samples of carbon to routine precisions of about 0.3% (±24 radiocarbon years). Developments in the last decades have allowed for even smaller samples. Higher precisions, down to about 0.2% can be obtained by longer counting times or multiple measurements.

The environmental and health-damaging effects of “high aerosol concentration” periods often represent an issue in Hungary, which is mainly due to the country's location (basin is within the Carpathians). The main sources of carbonaceous aerosol are already more or less known, but the numerical extent and temporal distribution of the contributions are still the subject of numerous investigations in the region. In these researches, isotopic analytical procedures are increasingly involved, which, in addition to traditional analytical methods, enable us to make more and more accurate source apportionment analyses. By means of the radiocarbon method, the modern and fossil fuel sources can unambiguously be separated, while levoglucosan can be used as tracer to distinguish the two largest modern sources i.e. biological emissions and anthropogenic wood burning. In the first half of 2015, a comprehensive PM10 collection campaign in five big cities (Budapest, Debrecen, Miskolc, Pécs, Nyíregyháza) was completed, financed by the Hungarian state. Its purpose was to identify the most relevant emission sources and quantify their contributions as accurately as possible. In the course of the analyses, mass concentration of the total, organic and elemental carbon (TC, OC, EC, respectively) of the collected samples were determined, in addition, the specific 14C activity and levoglucosan concentration of TC were also measured. Our studies clearly revealed the predominance of the anthropogenic wood burning source in the winter/heating period, but the contribution of biological sources ranged in a broader scale during the observation period. Contrarily, the contributions from fossil sources were relatively balanced for the same period.

The global impact of COVID-19 on communities and economies has led to questions about decreasing environmental risks and pollution due to the decreased industrial and transport activity. One of the key concerns revolves about the atmospheric rise in CO2 levels and the associated arising fossil carbon load, constituting the global climate change. The quantification of fossil-origin atmospheric carbon load is addressed through the use of natural radiocarbon (14C), a unique scientific tool. Fossil sources lack 14C activity, while recent biogenic carbon contains radiocarbon. This study centers on revealing long-term trends in atmospheric 14C levels, particularly during the year of the pandemic, in comparison to the preceding five years in Hungary. Atmospheric CO2 and tree rings from the studied six years were subjected to 14C analysis from three distinct locations. One of the examined cities, Budapest - Hungary's capital - is a highly urbanized land with a reported 1.7 million population. Despite the city's extensive vehicular and human activity, a "state of danger" was in effect in Hungary from March to June 2020 due to the first wave of COVID-19. The sampling sites had been characterized by a busy urban environment, with a mix of vehicular activities contributing to the local atmosphere. The second urban sampling site is Debrecen, a smaller but evolving city that can be found in the eastern part of Hungary. It’s the second largest Hungarian city - around 200 thousand citizens – and it is currently experiencing an industrial revolution by the construction of major factories. Significant contribution to pollution in this area come from urban vehicular traffic and the surrounding agricultural regions. The background 14C signal used in the study is from the easternmost Integrated Carbon Observation System(ICOS) atmospheric regional background station (HUN) and NOAA background site, at Hegyhátsál. Mole fraction has been continuously monitored at four elevations at HUN station since September 1994. For this research integrated atmospheric 14CO2 samples, supplemented with CO2 mole fraction measurements, were used from October 2014 to December 2020. The data was studied from the aspect of temporal variation and altitudinal differences. CO2 mole fraction data of the free tropospheric background ICOS station at Jungfraujoch (Switzerland) were used. The outcomes of the trend analysis reveal the fluctuations in atmospheric fossil carbon load throughout the pandemic, which offers valuable insights into the environmental effects of reduced human activities in Hungary. Prepared with the professional support of the Doctoral Student Scholarship Program of the Co-operative Doctoral Program of the Ministry of Innovation and Technology financed from the National Research, Development and Innovation Fund and supported by the PARIS project (Grant Agreement No. 820846), which is funded by the European Commission through the Horizon 2020 research programme.

During the Late Neolithic and Early Bronze Age, migrations and the advent of working bronze alloy materials triggered profound cultural, social, and economic shifts across Central Europe. As a result of this processes, many communities with distinct archaeological and cultural characteristics emerged during the Central European Early Bronze Age (between circa 2200/2100 and 1600/1500 BC) in Central Europe, and with the Middle Bronze Age of the Carpathian Basin (between 2000/1900 and 1500/1450 BC). This study examines the biological relationships among these populations through biodistance analyses, aiming to clarify connections between cultural and biological affinities within the emerging heterogeneous communities. Craniometric and population graph analyses highlight the Danube’s complex role as a barrier to gene flow across Early Bronze Age communities. The population graph analysis suggests varying connectivity among male and female groups. Beside geographical location and sex-biased mobility, population admixture may have had an impact on the formation of population structure in the Early Bronze Age, as communities north of the Danube have more connections to Corded Ware cultures, whereas southern groups are more closely associated with Bell Beaker populations.

Radiocarbon (14C) is one of the key isotopes in the field of nuclear environmental protection. This difficult-to-measure isotope constitutes a substantial proportion of the nuclear industry's dose contribution, underscoring the imperative for precise measurement in regions loaded by 14C emissions. The currently used technologies such as accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) techniques are capable of determining the exact 14C content or ratio of 14C-enriched samples. However, the evolving, laser-based spectroscopic methods, such as Saturated-absorption CAvity Ring-down (SCAR) technology, may offer a fast, reliable, and cost-effective alternative for the analysis of lightly labeled carbonaceous materials or slightly 14C-enriched environmental and plant samples. The 14C-enriched plant samples examined in the study demonstrated that the SCAR method is capable of reproducing AMS measurement results with a difference of less than 4 % when measured from the same gas after δ13C correction. This study constitutes the inaugural demonstration and practical exemplification of subsamples formed from the same CO2 gas, after the combustion, being measured by AMS, SCAR, and Isotope Ratio Mass Spectrometry (IRMS) for 14C/12C and 13C/12C isotope ratios. The comparative study demonstrates that SCAR is capable of measuring the 14C/12C ratio of plant samples between 115 and 2600 pMC with sufficient accuracy and linearity, providing a new alternative for nuclear environmental protection and research in the case of organic samples exceeding the natural environmental level (∼100 pMC).

Earthworm biospheroids are a useful alternative to radiocarbon ( 14 C) soil dating. In this study, we undertook a series of measurements to test the 14 C dating potential/performance of recent earthworm biospheroid granules. A novel sample preparation protocol for 14 C in biospheroids was developed and elaborated at Atomki (Institute for Nuclear Research) and tested on IAEA reference materials. 24 natural biospheroid samples were extracted from five different location/environment-eight topsoils (A-horizon soils). Bomb-peak-based, high-resolution 14 C dating show very uniform 14 C results at 105.6 ± 2.6 pMC (1σ) and none of the biospheroids are older than 30 yr. It also shows that no biospheroid with a 14 C bomb-peak as high as that observed in the 1960s and 1990s were observed. The results confirmed that earthworms do indeed consume almost exclusively recent biogenic carbon, not other organic compounds or inorganic carbonates previously bound in the soil. The calendar age of their biospheroids were extremely close to the real (zero) age of the surface. Thus, no “reservoir effect” is seen for these macrofossils. We conclude that a biospheroid-based 14 C age determination method may be suitable to measure the burial time as long as earthworm biospheroids can be found in the soil.

The Cunene region of southern Angola, especially the area around Xangongo, hosts a large number of African baobabs, including several superlative specimens. Our research reports the investigation of the three biggest specimens from Xangongo Grove, named XG-1 (11 stems; circumference 26.34 m), XG-2 (5 stems; 22.70 m) and XG-3 (9 stems; 27.73 m), and of the largest baobab from Xangongo town, named XT-1 (7 stems; 21.02 m). Several wood samples were collected from these four baobabs mainly as cores from trunks and/or primary branches and then radiocarbon-dated by AMS. The two oldest samples were extracted from two primary branches of baobab XG-1. These have practically identical radiocarbon dates of 1822 ± 19 BP and 1822 ± 10 BP, which correspond to identical calibrated ages of 1785 ± 15 and 1785 ± 10 calendar years. The calculated age of baobab XG-1 is 2100 ± 50 years. Thus, XG-1, which is called by the locals “The biggest baobab of Africa”, becomes the oldest living African baobab with accurate dating results. The results indicate ages of 1100 years for baobab XG-2, 850 years for baobab XG-3 and 550 years for baobab XT-1.

The increasing level of atmospheric greenhouse gases and the effect of this trend, climate change, is one of the greatest environmental issues of the anthropogenic era. The increasing trend of greenhouse gas levels after industrialization is related to urban environments, where industrial and traffic-related activity and emissions are concentrated. In response to this, the European system, the ICOS (Integrated Carbon Observation System) was established and started the ICOS cities program, where coordinated greenhouse gas observations are carried out besides the regional background measurements and samplings. Similarly to this program, atmospheric air samples were collected at the Institute for Nuclear Research, Debrecen. During the sampling campaigns in three different seasons (winter, spring and summer), a minimum of 23 samples were collected in the morning and afternoon during weekdays and weekends as well. The samples are processed within a collaboration between Utrecht University, where the stable isotope composition of CO2 and CH4 were measured, and the Institute for Nuclear Research, Hungary, where the mole fraction of CO2 and CH4 and radiocarbon ratio of CO2 were measured. Based on the isotope composition results and stable isotope fingerprint of carbon dioxide and methane sources, the differentiation of the possible emission sources of these gases can be made. Using the radiocarbon, we can estimate the fossil CO2 contribution in urban areas. The preliminary results show that there is a great fossil contribution to the CO2 fraction, on the other hand, a great local biological contribution was observed in the CH4 fraction in every season. Based on measurements and literature, the source of the massive biological discharge could be the sewage pipeline system, even in winter. Our dataset shows that this kind of CH4 emitter can exceed fossil sources in Debrecen, Hungary.

Terrestrial plants maintain carbon reserves to support their functions during periods when metabolic demand exceeds carbon supply, such as during the dormant season (Carbone et al. 2013). Urban trees may differ in the size and age of these carbon pools due to their specific environmental conditions, especially more stressful environment and occasional lack of water. In order to better understand the carbon storage strategy of urban trees, tree-ring core samples were collected in a medium-sized Hungarian city, Debrecen, from Celtis occidentalis trees located in different urban areas, such as downtown and suburban sampling points. In addition to the tree rings, bud samples were also collected to determine the age of carbon used for the production of new plant tissue during spring. The accelerator mass spectrometry-based bomb-radiocarbon approach was used determine the age of the carbon stored in the plant and bud samples (Richardson et al. 2015, Richter et al. 2009.). The results show that fresh carbon was used to produce new spring buds and the results show that the possible fossil contribution in urban areas can shift the age of fresh plant material. In contrast, our previous study showed that non-urban trees use much older carbon to produce buds (Varga et al. 2024). Although the trees studied used fresh carbon to build new tissues, the sugar and starch concentrations and their radiocarbon ages show that there is a low but considerable amount of stored carbon in the urban trees. The 14C measurement reveals the turnover time and mixing of old and fresh carbon in the tree, and shows a declining trend in the stored carbon concentration by the years. References Carbone et al. 2013., Age, allocation and availability of nonstructural carbon in mature red maple trees. New Phytologist 200(4): 1145–1155.Richardson et al., 2015. Distribution and mixing of old and new nonstructural carbon in two temperate trees. New Phytologist 206(2): 590–597.Richter et al., 2009. Preparation of starch and soluble sugars of plant material for the analysis of carbon isotope composition: a comparison of methods. Rapid Commun. Mass Spectrom. 23, 2476–2488.Varga, et al., 2024. Spring buds of European woody plants have old 14C age. Heliyon 10.

The main goal of ICOS Hungary was to expand the geographical coverage of the ICOS network towards Eastern Europe. As Hungary is located in the zone of westerlies winds in Europe, adding measurement stations East of the existing ICOS network may significantly reduce the uncertainty of the continental atmospheric CO2 and CH4 budget models. Since the joining of HUN it is (almost) the easternmost ICOS atmospheric background station. ICOS has high expectations for all the stations seeking to join the observation system. These expectations include ensuring the highest quality and employing state-of-the-art equipment available in the stations. Atmospheric stations wishing to connect to the network has to develop their gas handling systems themselves. This requirement places additional responsibility on the operators of stations to create their own systems, allowing them to tailor gas handling processes to their unique needs and in accordance with ICOS network specifications. The gas handling system for the HUN station, was built in the collaboration between ATOMKI and Isotoptech Zrt., that has been developed for the possibility of commercial use also. This developed system has been operational in Hegyhatsal since the spring of 2022. The core of the system's is a Picarro analyzer (CO2, CH4 and H2O), that requires properly filtered and semidried air for operation. According to the expectations, the developed system meets all the ICOS requirements, including minimized response time, addressing memory effects, and ensuring appropriate flushing capacity. It operates in five independent sampling height (at HUN connected to elevations at 115m, 82m, 50m, 10m and a spare one) with a sampling rate of 10 l/min. Each line uses 2-micron filters before the Picarro, and one multiport VALCO rotary valve runs for efficient and precise environmental GHG gas analysis. For the purpose of ensuring analytical security, high-performance KNF inert pumps are employed for sample transfer/flushing in order to maintain the integrity and reliability of the analytical process. From 2022 the monitoring station continuously measures atmospheric concentrations of CO2, CH4, and other trace gases at the four sampling levels. The entire novel, compact gas handling equipment (made by Isotoptech) has stand-alone design, with a footprint of less than 1 m2, 2 m height, integrates all the components, and is designed for easy mobility. The gas handling system has undergone one year of routine operation with minimal maintenance requirements, proving to be reliable and consistently operational even while it is managed remotely from a distance of 500 km, without significant disruptions. Prepared with the professional support of the Doctoral Student Scholarship Program of the Cooperative Doctoral Program of the Ministry of Innovation and Technology financed from the National Research, Development and Innovation Fund and supported by the PARIS project (Grant Agreement No. 820846), which is funded by the European Commission through the Horizon 2020 research programme.

In our previous research, we observed a discrepancy between the apparent14C 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 (13C/12C and 14C/12C) 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, 14CO₂ 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 14C/12C nectar results, the findings underscore the potential for older carbon stored in soil or plants to enter the food chain through nectar.