Impact of the Fukushima Accident on 3H and 14C Environmental Levels: A Review of Ten Years of Investigation.

The investigation of the impact of the Fukushima accident is still going on although more than ten years have passed since the disaster. The main goal of this paper was to summarize the results of tritium and radiocarbon determinations in different environmental samples, possibly connected with the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. A document containing compiled data may serve as a solid basis for further research in the selected fields. To accomplish such effort, we went through dozens of relevant published papers, reporting 3H and 14C activity concentrations in precipitations, groundwater, seawater, river systems, tree rings, and, in some more extraordinary samples, such as herbaceous plants or debris from the damaged reactor buildings. As the referenced results would not be obtainable without adequate analytical techniques, the most common methods for routine measurement of tritium and radiocarbon concentrations are discussed as well. We believe that the correct identification of the affected environmental compartments could help quantify the released 3H and 14C activities and track their following fate, which could be especially important for plans to discharge contaminated water from the FDNPP in the upcoming years.

Radiocarbon in tree rings from a clean air region in Slovakia.

In order to study radiocarbon levels at a clean air location in Slovakia with no significant local anthropogenic effects, we took tree ring samples from a tree in the vicinity of Jasná recreational area in the Low Tatras region in the central part of Slovakia. There are no significant local fossil fuel emission sources, so these samples represent a regional clean air background important for 14C studies in Slovakia and Central Europe. The growth rings from the sampled tree (European spruce, Picea abies) cover the period from 1911 to 2016. The first part of the data (1911-1952) represents natural radiocarbon levels influenced by Suess effect. The following period exhibits an increase in radiocarbon levels due to atmospheric nuclear weapons tests (Δ14C maximum of 850‰ in 1964), and then a gradual decrease characterized by an exponential trend with time constant of 14.3 ± 0.5 years. The Δ14C data from Jasná was used as a reference for comparison with two previously reported modern tree ring data sets from Slovakia. This comparison showed that radiocarbon levels at both locations are lower than clean air reference values, indicating the influence of local fossil fuel emissions.

Radiocarbon analysis of carbonaceous aerosols in Bratislava, Slovakia.

Aerosols dispersed in the atmosphere represent important factors influencing not only the environment, but also human health. Carbonaceous aerosols are one of the main components of total atmospheric aerosols, and their sources are of great interest. Radiocarbon analysis provides an excellent way to determine the fraction of fossil and non-fossil aerosols in the atmosphere. Over the period of one year (June 2017-June 2018), we sampled atmospheric aerosols with size greater than 0.3 µm in Bratislava, Slovakia and used the exposed quartz filters for radiocarbon analysis of the elemental carbon (EC) aerosol fraction. The results show that on average the fossil fuel combustion is the dominant source of EC aerosol particles in Bratislava. In summer months, they represent more than half (65-80%) of the total EC aerosols. The relative amount of EC particles derived from biomass burning was 20-35% in summer, which increased to 40-55% in winter months. The dominance of fossil fraction is caused by high degree of industrialization and urbanization of the city. The increase of biomass fraction in winter is probably caused by domestic wood burning in areas surrounding the Bratislava city.

Radiocarbon and 137Cs dating of wines.

Wine dating methods based on anthropogenic 14C and 137Cs, as well as on the cosmogenic 14C were studied with the aim to improve the accuracy and precision of the dating results. While the 14C dating method has proved to be useful for dating young and old wines, the 137Cs has been effective for dating of wines originating around the 137Cs bomb-peak observed in 1963. A new method was developed for simultaneous 14C and 137Cs dating of wines, which helped to distinguish wines originating before or after the bomb peak. The δ13C values also helped to solve the 14C age ambiguity in dating of wines around the 14C bomb peak. While the 14C dating method is always destructive one, the 137Cs method may use a radiochemical separation of cesium from wine samples when better precision of results is required, but it can be also a nondestructive one with direct gamma-spectrometry of wine samples, especially those that are very rare.