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Natural radionuclides can be concentrated in coal ash and slag. When such a waste is deposited in the envi- ronment, it is normally inhabited by different animals and plants. Earthworms are one of the most exposed as they live in close contact with such a waste throughout their entire life. Po-210 and Pb-210 represent one of the most radiotoxic radionuclides, especially when ingested. Within this study we wanted to assess the uptake of Po-210 and Pb-210 by earthworm Eisenia fetida transplanted on the coal ash and slag sampled from the former chemical factory in Kaštela Bay (Croatia). Uptake was compared with cultivation on non-contaminated and reference soil. After cultivation period of 28 days, earthworm samples were cleaned. From one set of samples, which was used also for cytotoxic and genotoxic investigations, coelomic fluid was removed and from other not. They were dried at 65 °C. Then the samples were digested and Po was spontaneously deposited on Ag disc and Po-210 activity concentration was determined by alpha-particle spectrometry. Pb-210 was separated using Sr Resin column and measured by gas-flow proportional counter. Results show that Po-210 activity concentrations in earthworms cultivated on coal ash and slag were in the range of 43-93 Bq/kg, whereas on non-contaminated and reference soil values were in the range of 17-39 Bq/kg. Therefore, Po-210 activity con- centrations found in earthworms cultivated on coal ash and slag are 2-3 times higher compared to control group. Similar observation was found for Pb-210 only for samples without coelomic fluid, where samples with coelomic fluid did not show any significant difference between those cultivated on coal ash and slag and control ones. This indicates different distribution of Pb-210 and Po-210 between coelomic fluid and other earthworm’s body compartments.

Industrial residues and wastes with higher content of naturally occurring radionuclides represent a potential ecological risk to the biota residing in the vicinity of the disposal sites. Coal ash and slag landfills are widespread due to usage of coal as fuel in thermal power plants worldwide. Combustion of coal results in preconcentration of radionuclides naturally present in coal in its residual ash as well as the spread of the ash particles at greater distances. Earthworms represent one of the most important group of terrestrial organisms and are therefore often used in ecotoxicological studies. The aim of this study was to determine the influence of weathered coal ash and slag with enhanced content of radionuclides from uranium decay chain that were sampled in the area of the former chemical factory in Kaštela Bay (Croatia), on biochemical markers (protein, lipid and carbohydrate content, lipid peroxidation, GST and AChE activity), genotoxicity markers (Comet assay and micronucleus test), cytotoxicity (neutral red uptake assay) and reproduction of the earthworm Eisenia fetida. The results have shown that 28 days exposure to those substrates cause oxidative stress, genotoxic and cytotoxic effects and inhibit reproduction. Compared to the control samples, earthworms exposed to the coal ash had significantly higher activity concentrations of Po-210, a member of uranium decay chain and one of the most radiotoxic naturally occurring radionuclide. Coelomic fluid expression had no significant impact on the activity concentrations of Po-210 in earthworms, indicating that polonium is mostly deposited in the soft tissues.

Tritium (3H) as a constituent of the water molecule is an important natural tracer in hydrological sciences. The anthropogenic tritium introduced into the atmosphere unintentionally became an excellent tracer of processes on a time scale of up to 100 years. A prerequisite for tritium applications is to know the distribution of tritium activity in precipitation. Here we present a database of isoscapes derived from 41 stations for amount-weighted annual mean tritium activity in precipitation for the period 1976 to 2017 on spatially continuous interpolated 1 km×1 km grids for the Adriatic–Pannonian region (called the AP3H_v1 database), with a special focus on post-2010 years, which are not represented by existing global models. Five stations were used for out-of-sample evaluation of the model performance, independently confirming its capability of reproducing the spatiotemporal tritium variability in the region. The AP3H database is capable of providing reliable spatiotemporal input for hydrogeological application at any place within Slovenia, Hungary, and their surroundings. Results also show a decrease in the average spatial representativity of the stations regarding tritium activity in precipitation from ∼440 km in 1970s, when bomb tritium still prevailed in precipitation, to ∼235 km in the 2010s. The post-2010 isoscapes can serve as benchmarks for background tritium activity for the region, helping to determine potential future local increases in technogenic tritium from these backgrounds. The gridded tritium isoscape is available in NetCDF-4 at https://doi.org/10.1594/PANGAEA.896938 (Kern et al., 2019).

Tritium (3H) as a constituent of the water molecule is an important natural tracer in hydrological sciences. The anthropogenic tritium introduced into the atmosphere became unintentionally an excellent tracer of processes on the time scale of up to a 100 years. A prerequisite for tritium applications is to know the distribution of tritium activity in precipitation. Here we present the spatially continuous gridded database (isoscapes) for amount-weighted annual mean tritium activity in precipitation for the period 1976 to 2017 on 1 × 1 km grids for the Adriatic-Pannonian Region (using 39 stations), with a special focus on post-2010 years which are not represented by existing global models. Three stations were used to check the model performance independently confirming its capability to reproducing the spatiotemporal tritium variability in the region. This Regional model is capable of providing reliable spatiotemporal input data for hydrogeological application at any place within Slovenia, Hungary and its surroundings. Results also show a decrease in the average spatial representativity of the stations regarding tritium activity in precipitation from ~ 600 km in 1970s when bomb-tritium was still prevailing in precipitation, to ~ 300 km in the 2010s. The post-2010 isoscapes can serve as benchmarks for background tritium activity for the region, helping to determine local increases of technogenic tritium from these backgrounds. The gridded tritium isoscape is available in NetCDF-4 at doi:10.1594/PANGAEA.896938 (Kern et al., 2019).

Tritium is an important natural tracer in hydrological sciences. The dataset used in the present study is compiled of ~7, 700 monthly precipitation tritium activity values from 71 stations, covering the period from Jan 1961 to Dec 2017. As a pre-processing step, a sequential univariate outlier detection procedure was applied in which the time series of the stations were pairwise compared for each year. Variogram analysis was then applied to the precipitation amount weighted annual averages of tritium activity. Variograms applicable for interpolation were obtained from years 1977, 1982, 2007, 2010, 2011 and 2012. These where further on used as the reference years, and their variograms were used as the weights for kriging in the intermediate years. It suggests a decrease in spatial representativity of the precipitation monitoring stations from 590 km in 1977 to ~270 km in 2012, which might reflect the diminishing influence of broadly homogenous anthropogenic disturbance (i.e., global effect of bomb tests) on natural tritium levels of precipitation. Since 3H activity in the region approximated the natural level in precipitation by the early-1990s, it can be expected that the ~270 km range obtained for the 2012 reflects the natural 3H variability. The final product of the research was a database of the interpolated 1x1 km grids of each year’s tritium activity.

Tritium is an important natural tracer in the hydrological sciences. Measurements of the tritium activity of precipitation in the Adriatic-Pannonian region began in Vienna Hohe Warte in 1961, which is the longest continuously operating station in Central Europe. The dataset used in the present study is compiled of ~7500 monthly precipitation tritium activity values from 68 stations covering the period from Jan 1961 to Dec 2017. To maximize the spatiotemporal density of the data not only the Adriatic-Pannonian region, but the bordering areas were included in the analyses as well. Changes in the availability of tritium data from the different stations outlined three time horizons with a relatively high abundance of data, i.e. early 1980s (n≈15), late 2000s (n≈21) and the 2010s (n≈19). Two years were chosen from each period for investigation where the station densities reached their maxima. Variogram analysis was applied to the amount weighted annual averages of tritium activity. The results suggested a decrease in spatial representativity of the precipitation monitoring stations for the three time horizons (~500, ~400, ~300 km respectively), which might reflect the diminishing influence of broadly homogenous nthropogenic disturbance (i.e. global effect of bomb tests) on natural tritium levels of precipitation. However, this hypothesis needs further verification, primarily by including additional stations and archived data. Based on the preliminary evaluation at least 15 stations are required to derive a meaningful tritium isoscape for the Adriatic-Pannonian region. A further, almost trivial, requirement is that the stations should not be clustered instead well distributed over the region. As final products of the research, the annual precipitation tritium activities are mapped and presented as numerical data as well (1 km × 1 km grid) from the late 1970s to 2002 and after 2007 when the spatiotemporal data density was sufficient. The obtained product will provide a spatially more accurate reference for infiltration modelling, hydrological residence/transit time estimation and for the campaigns related to water resource protection. Last but not least, an accurate picture of the normal spatial distribution of precipitation 3H is of interest also due to the possible nuclear accidents. Acknowledgements: This work was supported by the National Research, Development and Innovation Office ; under Grant SNN118205 ; Slovenian Research Agency ARRS under Grants: N1-0054 and P1-0143, and the Ministry of Human Capacities under Grant NTP-NFTÖ-17-B-0028.

Nuclide 90Sr is one of twelve radioactive isotopes of strontium that has an artificial origin as a consequence of nuclear weapon testing during 1950s and 1960s, as well as the nuclear accidents. Based on its half-life of 28.8 y, this radionuclide can still be found in the environment as a result of these activities. The knowledge about behavior of 90Sr and also of its content in environmental samples is of extreme importance to prevent and control contamination, predominantly of food chain. For the purpose of this study, an agricultural soil from territory of the Republic of Serbia was investigated. The aim was to compare three different methodologies for the determination of 90Sr activity in soil samples and the interpretation of obtained results. The radiochemical analytical method of 90Sr determination via 90Y, radiochemical analytical method based on ion-exchange resins and radiochemical analytical method with fuming nitric acid were compared and evaluated. In all cases measurements were performed on proportional counter. The acquired results showed a good agreement between the compared methods.

Different radiometric techniques for the determination of U-238, Ra-226 and Pb-210 are presented and compared in terms of detection limits with mass spectrometric techniques. It can be concluded that when samples with low activity concentrations have to be measured, the method of choice in the case of U-238 should be either RNAA/INAA or alpha particle spectrometry. In the case of Ra-226 and Pb-210 the best performance can be expected by the alpha spectrometry, whereas drawback of waiting for establishing secular radioactive equilibrium of Pb-210 with Po-210 makes techniques like beta counting and LSC more attractive for the determination of Pb-210. In addition, a case study on monitoring the former uranium mine Žirovski vrh is presented along with the used methodology and the summarised measurement results.

Measurement of 226Ra activity concentrations is often used to estimate supported levels of 210Pb for purposes of geochronology. However, the implicit assumption that supported 210Pb and 226Ra are in secular radioactive equilibrium may not always be true because of the migration of an intermediate product, gaseous 222Rn. As a consequence, supported 210Pb activity concentration might be lower than the measured 226Ra value, which was the case in a core collected from the South Adriatic Pit. Here we present a new approach to improve the determination of supported 210Pb, which is based on correction of 226Ra activity concentrations using the average (210Pb/226Ra) activity ratio in deeper sediment layers. Using this approach, sedimentation rates for the South Adriatic Pit with a constant rate of supply model and a constant initial concentration model were 0.054 g/cm2/a and 0.070 g/cm2/a, respectively.