20-EPN2-018: Structure of the radiocarbon calibration curve around Miyake effect in 660 BC, AD 775 and AD 994

20-EPN2-018: Structure of the radiocarbon calibration curve around Miyake effect in 660 BC, AD 775 and AD 994

Visit by Andrzej Rakowski, Silesian University of Technology (Poland) to TA2 Facility 16 – Carbon-14 Dating AMS Laboratory (Hungary).
Dates of visit: 6-26 July 2022

Report Summary: Evidence of a rapid increase in the radiocarbon concentration of the tree rings for the year 775 CE was initially presented by Miyake et al in 2012 (henceforth called M12). Since then, other events similar to the M12 have been confirmed for different periods. This project aims to provide new information about the increase in concentration of radiocarbon in the period of abrupt solar activity. For the study we have chosen the periods in XIth and XIIIth century CE and in VIIth century BCE, in which increase of radiocarbon concentration was noted. The samples have been collected from dendro-chronologically dated trees, and the annual rings has been extracted for measurement.

During the Europlanet TA visit in the Isotoptech Zrt. AMS laboratory, all the samples were prepared to be measured using MICADAS AMS system. Each set of measurement was accompanying with standardsamples (of known radiocarbon concentration) to control the quality of the measurement. To obtain high precision (<2 ‰) the measurement time was extended. The results show occurrence of Miyake events in analyzing periods. For the analyzing period in VIIth century we were able to determinate the occurrence during the year, by dividing the annual ring into three parts early-wood, early-late wood and late wood. During the TA visit we have possibility to learn about the procedures used in the laboratory to prepare samples (of different kinds) for radiocarbon measurement using AMS system. We had a fruitful discussion on possible future cooperation, including joint submission of a research project proposal.

Read full scientific report, with kind permission by Andrzej Zbigniew Rakowski.


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20-EPN2-025: Determining the C-14 ages of offshore groundwater by analysing fluid samples with small quantities

20-EPN2-025: Determining the C-14 ages of offshore groundwater by analysing fluid samples with small quantities

Visit by Nai-Chen Chen, University of Stockholm (Sweden) to TA2 Facility 16 – Carbon-14 Dating AMS Laboratory (Hungary).
Dates of visit: 14-25 March 2022

Report Summary: Submarine groundwater discharge (SGD) has been shown to be an important mechanism in transporting solutes from the terrestrial to the marine environment. Despite being a well-documented process, our knowledge about the timing of offshore groundwater emplacement is extremely scarce. We aim to develop an age-dependent numerical model in our study area to investigate the relationship between SGD and the carbon cycle, whereby the obtained 14C age of the groundwater is used as a constraint. Our goal is to analyze all the carbon pools present in our cores (i.e. TIC, TOC, DIC and CH4) for 14C, so that we can correct for possible interference with the 14C-DIC signal (used for groundwater age). This is a challenge however, as the carbon content for some of these samples is extremely low.

During this two-week visit, we not only learned about the 14C preparation methods and operation of Accelerator Mass Spectrometry (AMS), but also discussed and exchanged ideas with Isotoptech AMS C-14 group scientists. Preliminary 14C results indicate that 14C depleted DIC is observed closer to the sediment-water interface for cores with anticipated SGD. This can be explained by the advective upwards transport of older groundwater. The discrepancy between the TIC and TOC 14C content at similar core depths was found to be very large, indicating that these carbon pools are affected by different processes. This mismatch might be a result of the precipitation of authigenic carbonates or microbial activity. 


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