Radiocarbon (14C) has an important role both in the environment and climate research as well as in radiocarbon dating. As a natural tracer, radiocarbon can be applied to differentiate fossil or modern derived inorganic and organic compounds. Although fossil materials do not contain radiocarbon, recent modern materials have a well-measurable radiocarbon content as they are closely related to the atmospheric carbon dioxide. In certain cases, different methods apart from the isotope analysis cannot be applied to discriminate the two sources, like in the case of the discrimination of fossil and modern CO2 emissions (Suess, 1955). The method is not only applicable for discrimination of emission sources, but also in industry for the investigation of materials containing fossil and bio components as well, like plastic and fuel samples (Oinonen et al., 2010). In addition, the 14C emission of nuclear facilities can be investigated, as the 14C/12C ratio of nuclear emission are easily distinguishable from the natural background (Zhang et al., 2021). Plants collect and fix the carbon from the atmospheric CO2 by the photosynthesis, for this reason, some plant organic material, like cellulose, well represent the local atmospheric 14C/12C ratio of CO2 in the year of the production (Rakowski, 2011; Richardson et al., 2013). Based on this, plant materials (tree rings and leaves) can be applied to high spatial and temporal resolution passive sampling in urban and rural areas or around nuclear power plants, for recent and retrospective investigations. By this method, areas can be investigated, where instrumental sampling is not possible or would be very costly. Furthermore, the method is applicable to signals of extraterrestrial events, that cannot be performed by ordinary instrumental sampling, like investigation of 14C fingerprints of the supernova explosions in tree ring samples, which are over a thousand years old (Miyake et al., 2012)
My presented PhD work was performed in the Eövtös Lóránd Research Network, Institute for Nuclear Research (ATOMKI), Isotope Climatology and Environmental Research Centre (ICER). In my research I was aiming to develop and apply accelerator mass spectrometry (AMS) based radiocarbon measurement methods that have not been applied in Hungary for environmental research. My aim was mapping the fossil carbon load in urban and background areas with high spatial resolution without instrumental air sampling, based on plant samples in Hungary (Debrecen) and Indonesia (Bali). In addition, I aimed to determine the effect of the Fukushima nuclear accident for the level of 14C in tree ring samples, 50 km west from the Fukushima Nuclear Power Plant. Beside nuclear emission, my research aim was also the investigation of the 14C fingerprints of natural cosmic events in tree ring samples. I tried to reproduce a previously published rapid 14C increase event in tree ring samples produced between 3351-3392 BCE. Furthermore, I wanted to expand the application of the applied 14C methods for such type materials that have not been investigated in Hungary before, such as fuel and honey samples. By these studies, in addition to radiocarbon dating, my aim was to open new perspectives in the Hungarian radiocarbon research, that can be the base of long-term researches in the future and open new research directions.