Scientists from NCBJ and the Institute of Geophysics of the Polish Academy of Sciences have published the results of many years of research on radionuclide concentrations in the polar region and in Poland. The collected data enriches the knowledge about the movement and mixing of air masses on a regional to global scale, and about environmental dust.

The paper, which will be published in the December issue of the Journal of Environmental Radioactivity, presents the results of measurements of the concentration of selected gamma-radioactive radionuclides (7Be, 210 Pb, 40K, 137Cs, 134Cs) occurring in aerosols of the ground layer of the atmosphere. The concentration of radionuclides in these studies was recorded in the years 2002-2017 at two stations: the Polish Polar Station of the Institute of Geophysics of the Polish Academy of Sciences in Hornsund and at the Geophysical Observatory of S Kalinowski Institute of Geophysics, Polish Academy of Sciences in Świder.

Since 2002, the AZA-1000 high-performance air intake system, adapted to work in low temperatures, has been operating in Hornsund. The Polish station is one of the few devices located closest to the North Pole (77°00’N, 15°33’E). As a result, the impact of air pollutants generated by human activity in this area is significantly limited. The Hornsund station is also the only polar station where measurements are carried out over such a long period.

For comparison, the second station used for the research is ASS-500, located in the region of Otwock forests (52°07’N, 21°15’E). This station has been operating with small breaks since 1991, and in the years 2002-2009 it was part of the nationwide network of radiological air monitoring. Thanks to its location in the middle latitude, the human influence on air pollution is much greater, which creates very good conditions for comparison, among others variability of air dustiness or radionuclide concentration.

The samples intended for research were collected in the same way at both stations. The devices are equipped with a high-performance forced air flow system. Aerosols were collected on the so-called Petrianov filters at weekly intervals, which gave about 50,000-100,000 m3 of air pumped. Then the filters were delivered to the measuring station located at NCBJ. Filters from the station in Hornsund were delivered every six months, which made it necessary to recalibrate the data obtained from them. After proper preparation of the filters (drying, weight assessment of the amount of aerosol and pressing into a disk with a diameter of 4.5 cm), they were sent for about 22 hours to the spectrometric measurement station using germanium detectors. In this way gamma radiation spectra were obtained, on the basis of which radionuclide concentrations were determined. The choice of the studied nuclides was obviously not accidental. Due to the spectrometers in the NCBJ laboratory, the focus was on gamma-radioactive radionuclides. Another criterion for their selection was their origin from various sources. In this way, isotopes of natural origin (210Pb, 40K) were selected as products of the decay of elements of the lithosphere, of cosmic origin (7Be), produced as a result of the interaction of cosmic rays with the atmosphere and those resulting from human activity (137Cs, 134Cs), m. in as decay products in the nuclear industry. Another criterion for their selection was their origin from various sources. In this way, isotopes of natural origin (210Pb, 40K) were selected as products of the decay of elements of the lithosphere, of cosmic origin (7Be), produced as a result of the interaction of cosmic rays with the atmosphere and those resulting from human activity (137Cs, 134Cs), m. in as decay products in the nuclear industry. Another criterion for their selection was their origin from various sources. In this way, isotopes of natural origin (210Pb, 40K) were selected as products of the decay of elements of the lithosphere, of cosmic origin (7Be), produced as a result of the interaction of cosmic rays with the atmosphere and those resulting from human activity (137Cs, 134Cs), m. in as decay products in the nuclear industry.

The results of the research clearly showed the differences in the concentration of individual radionuclides during the year. In the case of 7Be, maximum concentrations were observed in the polar regions during the winter season, while in mid-latitudes the maximum was observed in the summer months. The reasons for these differences are primarily the exchange of air masses in the stratosphere and troposphere (STE), vertical mixing of air masses in the troposphere (DT), horizontal transport (HT) and the capture of particles under the influence of atmospheric precipitation (WS). These factors also cause a higher average annual 7Be content in moderate latitudes compared to the polar regions. Additionally, a relationship between the concentration of this nuclide and the 11-year cycle of solar activity was observed – its concentration decreases with increasing solar activity.

Due to the different origin of the 210 Pb isotope, the maximum concentrations in both stations occurred in the winter months. At the same time, the phenomena mentioned in the case of beryllium do not have a significant impact on the seasonal distribution of 210 Pb. However, it is strongly related to the amount of dust, and its concentration decreases with increasing latitude.

As expected, a gradual decrease in the 137Cs content was also observed over time. This is due to the relatively short half-life of the isotope (about 30 years). Additionally, in 2011, both stations detected a significant increase in the concentration of cesium radioisotopes, which was related to the disaster of the Fukushima nuclear power plant.

Concentration of Cs-137 and Cs-134 in Świerk and Hornsund in 2011. There is a clear increase of approximately 9 weeks related to the Fukushima incident.

Both the 137Cs, 134Cs and 40K isotopes do not show any relationship between their concentration and the seasons of the year, but their concentration depends on the amount of dust. As in the case of lead and beryllium isotopes, the polar region is characterized by a lower concentration compared to the mean latitudes.

Even before publication, the research of NCBJ scientists was appreciated by the international scientific community. Proof of this is obtained by one of the authors, M. Sc. Michał Piotrowski, award for the best presentation during the International Conference on Radioecology and Environmental Radioactivity 2019 in Austria.

Both measuring stations operate to this day and still collect samples for further long-term tests. In addition, there are ideas to expand research on this topic, including analysis of alpha-radioactive radionuclides collected on filters or adding new stations to the research.

Original work:

Concentration of 7Be, 210 Pb, 40K, 137Cs, 134Cs radionuclides in the ground layer of the atmosphere in the polar (Hornsund, Spitsbergen) and mid-latitudes (Otwock-Świder, Poland) regions Agnieszka Burakowska, Marek Kubicki, Bogumiła Mysłek-Laurikainen, Michał Piotrowski, Halina Trzaskowska, Renata Sosnowiec

The work will be published in the December issue of the Journal of Environmental Radioactivity, Volume 240, December 2021, 106739, it is also available online at

https://www.sciencedirect.com/science/article/pii/S0265931X21002113?via…