The purpose of the study presented in the article is to implement modern hydrographic characteristics of freshwater of the Shatsk Lakes (28 lakes in Volyn Polissya, Ukraine) by typing water bodies according to the requirements of the EU Water Framework Directive, assessment of the chemical composition of lake water and bottom sediments (sapropel), determination of the opportunity for their recreational use in the special status of the district as a national park. Despite the presence of the two large lakes (Svityaz – 26.2 km ² and Pulemetske – 15.5 km ²), very small lakes with a water surface area of less than 0.5 km ² (64%) are dominating in the Shatsk group. Mineralisation of calcium-hydrocarbonate lake waters is 115–303 mg∙dm ^–3 and calcium-sulphate aqueous extract of sapropel is – 318–1451 mg∙dm ^–3. Using a Piper diagram, it was found that there is genetic homogeneity between surface and groundwater, indicating a significant share of groundwater in the water supply of lakes. There are eight species of sapropel deposits in 19 lakes of the district. A wide range of chemical composition and physical and mechanical properties of sapropel deposits of the Shatsk Lakes allow us to consider them as an important resource for agriculture and industry. We found that sapropel from Shatsk Lakes meets the requirements for therapeutic mud and can be used for therapeutic and health purposes.

Sapropel is a layer of sediment composed of organic and inorganic substances that accumulates at the bottom of lakes. The water of such lakes often have elevated levels of heavy metals such as Cd, Cr, Cu, and Zn, which can pose risks to human health. Sapropel may be used as a biosorbent in removing these heavy metals from aqueous solutions. Various doses of sapropel ranging from 1 to 50 g/L and different mixing times from15 to150 minutes have been tested. The maximum removal efficiencies for Cd (93%), Cr (31%), Cu (84%), and Zn (84%) from aqueous solutions were achieved using the minimum doses of sapropel (50 g/L). The study has shown that mixing sapropel for 15 minutes is sufficient for the removal of Cr, 30 minutes for Cd and Cu, and 60 minutes for Zn.

Sapropel deposits are widely distributed around the globe. In the Americas area they are adjacent to the Great Lakes region, in Europe sapropel deposits can be spotted in the territory of Scandinavia, France, Switzerland, Germany, Poland, Belarus, Russia and in the northern regions of Ukraine. Use of sapropel as a fertilizer can enhance high and stable yields of crops. However, despite the proven effectiveness of long-term practical researches in this area, nowadays sapropel is almost not used. One of the reasons - lack of developed processing methods of extraction and processing, including dehydration. Material properties as an object of interaction with the working bodies, change of their settings in the processing are crucial in the choice of technologies, development, bringing up to the necessary parameters and subsequent use. Sapropel high humidity (95-98%) is one of the main factor that determines the quality of its properties after the interaction with working bodies. However, in the process of decreasing, in interaction with oxygen, there are significant changes in physical and mechanical properties of sapropel. Decisive in the direction selection process of lake sapropels’ use in the economic sector is their moisture exchange and thermodynamic parameters. The complexity of setting the water apart, if freshly extracted sapropels possess only 15-20% of it, shows their strong water-retaining capacity. The above mentioned phenomenon proves the need for their use as an organic fertilizer during the crops growing, as superficial loss of moisture in the soil creates a new global problem. On the basis of deep analysis of the sapropels’ properties, the authors suggest three areas of freshly extracted lake sapropel application in mixtures with leafy part of the crops: in biogas production with its further use as an organic fertilizer; making a compost mixture of organic origin which physical and mechanical properties are approximate as that of the soil; alternative solid fuels in the form of briquettes.

The purpose of this study was to investigate the effect of a biological humic preparation – “HUMIN PLUS”, made from natural raw materials – environmentally friendly lake sapropel on the biological development of agricultural crops. The study consisted in obtaining information and assessing the effect of a biological product on the dynamics of seedlings development, planting density, as well as crop productivity. To assess the preparation, as well as to identify the effect on the stages of plant ontogenesis, the physicochemical parameters were studied, including the content of humates, and trace elements in the sapropel extract. To interpret the effect of the growth regulator on the seed germination energy, an adaptive-neural inference system was used. To establish the nature of the action of preparation on the development biology of plant, in the conditions of Kazakhstan, a series of experiments were carried out at different stages of ontogenesis of agricultural crops. It was found that the action of the “HUMIN PLUS” preparation significantly increases the content of essential and nonessential amino acids. The findings have established that the sapropel extract “HUMIN PLUS” affects the biological activity of plants, accelerating the seed germination and increasing the productivity of agricultural crops in Kazakhstan.