Link for citation: Maksimova A.A., Chernykh A.V., Novikov D.A., Dultsev F.F., Derkachev A.S., Sukhorukova  A.F., Nikitenkov  A.N., Khvachshevskaya  A.A. Toxic elements in groundwater in the northern regions of the Ob-Zaysan folded region. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.17-26. In Rus.

The relevance of this research lies in the need to study the distribution of elements of the first hazard class, uranium and thorium in the groundwater of the Ob-Zaisan folded area. Objective: to establish the characteristics of the hydrogeochemical background and to study the distribution of highly toxic chemical elements in the waters of the drinking water supply of the population. Methods. Rapidly changing parameters were determined using a field hydrogeochemical laboratory and field equipment Hanna HI98195 – a multi-parameter pH/ORP/conductivity meter, Hanna HI98198 – an oximeter. The measurement of radon activity in groundwater was carried out using the Alfarad plus complex. Laboratory studies of the chemical composition by means of titration, ion chromatography, mass spectrometry with inductively coupled plasma were carried out at the Research Laboratory of Hydrogeochemistry at the School of Earth Sciences and Engineering of the Tomsk Polytechnic University. The assessment of the toxicological characteristics of waters was carried out using the current regulatory documents: SanPiN 2.1.3684-21, SS R 58573-2019 and the recommendations of the World Health Organization. The hydrogeochemical background was calculated using the Statistica 8.0 software package (StatSoft. Inc.). To determine the extent of element concentrating in natural waters, the coefficients of concentration  and water migration (according to A.I. Perelman)  were calculated. Cumulative curves are calculated by the formula: Pc=Ri/(N+1). Results. The studied waters are HCO₃ Mg-Ca and HCO₃ Na-Mg-Ca composition with total mineralization varying from 203 to 1568 mg/dm³. The geochemical parameters of the environment are both reducing and oxidizing with Eh –331,6 – +438,5 mV, pH 6,6–8,3 with the content of O_2disol. 0,29–10,72 mg/dm³. The authors revealed relatively high concentrations of Ti – up to 0,04 mg/dm³, V – up to 0,03 mg/dm³, Fe – up to 93,9 mg/dm³, Zn – up to 0,38 mg/dm³, As – up to 0,27 mg/dm³, Zr – up to 0,018 mg/dm³, Sb – up to 0,016 mg/dm³, Ba – up to 0,51 mg/dm³, W – up to 0,005 mg/dm³, Hg – up to 0,0002 mg/dm³, Pb – up to 0,057 mg/dm³, U – up to 0,34 mg/dm³, which is probably related to the composition of host rocks and the spread of industrial enterprises developed in the study area. The elements of the first hazard class, as well as uranium and thorium, were studied in the work. It was found that 20 % of the studied samples were higher than the background value for beryllium, as well as for thallium and arsenic, 26 % – for thorium, and 19 % – for uranium.