Variations in the oxygen and hydrogen isotope composition of precipitation in Tomsk (2016-2020)
G.V. Simonova1, D.A. Kalashnikova1, A.N. Markelova1, A.S. Bondarenko1,2, A.E. Davydkina1,2
1Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences, 1Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences Tomsk, Russia
2Research Tomsk Polytechnic University, Tomsk, Russia
Keywords: precipitation, hydrogen and oxygen stable isotopes, deltaD, delta18O
Abstract
Changes in the oxygen (δ18O) and hydrogen (δD) isotope compositions of precipitation in Tomsk in the period from 2016 to 2020 are studied. It is found that the δ18O value varies in the range from -39.6 to +2.1‰, the average value over the entire period is -18 ± 6.8‰; the δD value varies in the range from -299 to -4.9‰, the average value is -118.7 ± 54.7‰. A Local Meteoric Water Line is calculated for the period from 2016 to 2020: δD = 7.43δ18O + 11.2; this equation indicates the predominance of evaporative fractionation. The dependence of the isotope composition of precipitation on temperature in Tomsk is derived: +0.47‰/°C for the δ18O value and +3.62‰/°C for the δD value. The main regions that provide atmospheric precipitation with different isotope compositions to Tomsk are identified based on the analysis of the airmass backward trajectories.
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