Modelling 210Pb downward transport in a natural peatland of Ilassky swamp massif in the European subarctic of Russia: IP-CRS model

The paper presents the results of the modelling of the transport of 210Pb down the peat core for the Ilassky natural bog massif. The activities of radionuclides 210Pb and 137Cs were investigated in the core layer by layer. Due to the nonexponential decrease of 210Pb activity, significant errors are possible in determining the age and accumulation rates of peat when applying classical dating models. The article presents 210Pb dating data obtained using the IP-CRS model. Data analysis showed that the vertical distribution of 137Cs and 210Pb is related to peat parameters: ash content and bulk density. The 210Pb dating of the core showed an age of 1963 for a depth of 17-19 cm, which is consistent with the 137Cs data. The dating of this horizon is indirectly confirmed by the data of the ash content and bulk density of peat. The above mentioned confirms the correctness and adequacy of the chosen model of dating of the natural peat bog. The peak of anthropogenic radionuclide content in peat deposits corresponds to 1963, the date of signing the Partial Nuclear Test Ban Treaty, being a reference point for geochronological studies. The results of linear accumulation rate, peat deposit mass accumulation rate and the magnitude of the atmospheric flux of 210Pb presented in the study are in good agreement with the data on peatlands of Northern Europe and the European Subarctic of Russia.