The results of studying the features of the spatial distribution of macro- and microelements in the “water – bottom sediments” system in the channel of the Uzynbulak creek (“Degelen” site of the Semipalatinsk test site, Kazakhstan) are presented. The studies were carried out in the summer of 2015. As a result of the study of the chemical composition in surface waters and bottom sediments of the Uzynbulak creek, the content of Li, Be, Na, Mg, K, Ca, V, Ni, Mo, Fe, Sr, Al, Zn, Ba, La, Ce, U was revealed. The nature of the origin and the main factors determining the increased content of a number of the studied elements have been determined. The main mechanisms of the formation of the elemental composition in surface waters, the degree of spreading of elements exceeding the MPC (maximum permissible concentration) beyond the “Degelen” site are considered.

Experimental studies of the selection of the most optimal homogenization, sample preparation procedure, and sample pressing parameters have been conducted. Reference samples were selected including eference standards with certified values of the content of elements and oxides. For enhancement of concentration ranges determined, 8 background samples with the most typical chemical composition in the STS territory were additionally selected. The content of elements in samples was certified by mass- and atomic emission spectrometry (ICP-MS and ICP-AES). Pressed pellets were prepared, a semi-quantitative X-ray fluorescent analysis (XRF analysis) of 8 samples with the known content was carried out by the ‘best detection’ to identify systematic discrepancies in determining compositions of samples using a destructive and non-destructive analytical technique and sample preparation.

The application of reference materials for the composition and properties of natural objects with certified characteristics is the main instrument for ensuring the correctness of the obtained analytical information in radioecological, geological, and other studies. The article presents the experience of the branch of the Institute of Radiation Safety and Ecology of the National Nuclear Center of the Republic of Kazakhstan in the development and certification of reference materials containing technogenic radionuclides and mass fractions of elements. The soil selected from the sites of underground and surface nuclear tests at the «Experimental field» and «Balapan» sites of the former Semipalatinsk Test Site, which has a diverse radionuclide composition (natural and technogenic radionuclides) with a wide range of chemical elements, was chosen as the starting material for production of reference materials. The main purpose of the work is the certification of two reference materials: reference material for the activity concentration of 137Cs, 90Sr, the mass fraction of Zn, Cu, Pb, Cd, Co, Fe, Mn, As in the soil cover of the Semipalatinsk Test Site (KZ.04.01.00007–2020) and reference material for the activity concentration of 152Eu, 60Co, the mass fraction of Zn, Cu, Pb, Cd, Co, Fe, Mn, As in the soil cover of the Semipalatinsk Test Site (KZ.04.01.00008–2020).All procedures necessary for the creation of reference materials were carried out: separation of the magnetic fraction from the bulk of the material, grinding of the material, control sieve of the material, as well as homogenization with subsequent analytical studies to certify the parameters of reference materials. The methods of gamma spectrometry, beta spectrometry, mass spectrometry, and combined measurement results processing were applied. The results of an interlaboratory comparative test to determine the certified value of the concentrations of the specified radionuclides and elements are given.Reference materials are soil samples dried to an air-dry state, grinded to a particle size of less than 60 µm, and packaged in hermetically sealed polypropylene containers weighing 200 g. Reference materials have been included in the register of the state system for ensuring the uniformity of measurements and approved as state reference materials of the Republic of Kazakhstan. The scope of reference materials is to provide interlaboratory quality control of tests of analytical laboratories specialized in conducting radioecological complex studies, as well as the development and validation of analytical measurement procedures.