From the novel results of comprehensive geological–hydrobiogeochemical studies conducted on Olkhon Island (Lake Baikal), it follows that the phenomenon of geophagy among wild and domestic ungulates on the island is caused by the deficiency of light subgroup rare earth elements (LREE) in plant food and natural waters, while not denying the possible role of other factors. This deficiency reflects the low LREE specificity of the most abundant metamorphic terrigenous carbonate rocks on the island, as well as their overlying eluvium–deluvium and soils. The resulting specificity of the landscapes may be the cause of the LREE imbalance in the nervous and hormonal systems of the body, which makes the animals regularly and periodically consume clay (kaolinite) products from weathering, enriched with the necessary nutritional elements. The identified cause of geophagy on Olkhon Island is likely to extend to a significant part of geophagy cases among animals, including humans, especially in the equatorial zone of the Earth.

Relevance. An original modeling method is presented, which allows obtaining qualitatively new results in practice of ecological-geochemical and biomedical research. Aim. To obtain new data on the forms of element migration in the conditions of animal and human organism parameters by means of physicochemical modeling (PC "Selector") with verification of calculated data with the results obtained for real natural objects and animal organisms. Objects. Samples of natural waters and tissues of wild animals. Methods. Computer modeling (PC "Selector"); inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7700x spectrometer) – 55 elements; atomic emission spectrometry (AES, spectrometer iCAP 7600 Duo) –- 5 macrocations; ion chromatography (IC, ion-liquid chromatograph LC-20) – 6 anions; inductively coupled plasma mass spectrometry (ICP-MS, mass spectrometer NexION 300D; scanning electron microscopes Hitachi S-3400N with Bruker X@Flash 5010 energy dispersive spectrometer. Results. By means of modeling, the authors have determined the qualitative and quantitative composition of the system "solution – crystalline substance". They took into account environmental conditions and physiological parameters of animal and human organism. Natural drinking water, gastric juice, mixture of drinking water and gastric juice were used as a solution, and crystalline substance was used as newly formed mineral phases in equilibrium with the solution. The work allowed establishing that the complexes assumed in the model experiment can be the cause of appearance of nanomineral phases of chemical elements in separate tissues of a living organism. Актуальность. Предложен оригинальный метод моделирования, позволяющий получить качественно новые результаты в практике эколого-геохимических и медико-биологических исследований. Цель. Работа нацелена на получение новых данных по формам миграции элементов в условиях параметров организма животных и человека с помощью физико-химического моделирования (ПК «Селектор») с заверкой расчетных данных результатами, полученными по реальным природным объектам и организмам животных. Объекты: пробы природных вод и тканей диких животных. Методы: компьютерное моделирование (ПК «Селектор»); масс-спектрометрия с индуктивно связанной плазмой (ICP-MS, спектрометр Agilent 7700х) – 55 элементов; атомно-эмиссионная спектрометрия (АЭС, спектрометр iCAP 7600 Duo) – 5 макрокатионов; ионная хроматография (ИХ, ионно-жидкостный хроматограф LC-20, Shimadzu) – 6 анионов; масс-спектрометрия с индуктивно связанной плазмой (ICP-MS, масс-спектрометр NexION 300D); сканирующие электронные микроскопы Hitachi S-3400N с энерго-дисперсионным спектрометром Bruker X@Flash 5010. Результаты. С помощью моделирования определен качественный и количественный состав системы «раствор – кристаллическое вещество» с учетом условий окружающей среды и физиологических показателей организма животных и человека, где в качестве раствора были природные питьевые воды, желудочный сок, смесь питьевых вод и желудочного сока, а в качестве кристаллического вещества – равновесные с раствором новообразованные минеральные фазы. Работа позволила установить, что предполагаемые в модельном эксперименте комплексы могут являться причиной появления в отдельных тканях живого организма наноминеральных фаз химических элементов.

The paper considers groundwater composition fluctuation within technogenic zones based on evidence from the flooded coal mines of Primorye. The authors have determined the regularities of hydrogeochemical processes, specified the groundwater composition fluctuation within the technogenic complexes located in the liquidated mine areas, and identified the equilibrium phases between the studied waters and specific secondary minerals. It has been proved that water within natural-technogenic complexes in the liquidated mine areas are saturated with silicates, carbonates, sulfates, oxides, and hydroxides, which should be taken into account when designing technologies for groundwater treatment.

Relevance. For the first time, comprehensive landscape-geochemical studies were conducted in the Buotama, Amga and Vostochnaya Khandyga river basins of Yakutia. The studies included the chemical composition of natural waters, soils, forage grasses, and rocks eaten by animals on kudurs, landscape complexes visited by animals for long periods of time for geophagy and specifically transformed by them. Aim. To determine the cause of geophagy occurring in these areas among wild and domestic animals. Methods. Atomic emission spectrometry, mass spectrometry, ion chromatography, analytical electron scanning microscope with energy-dispersive spectrometer. Results. It was revealed that geophagy in Yakutia is widespread both in mountainous and flat areas in landscapes with low contents of mobile forms of rare earth elements that can accumulate in feed and drinking water. It is assumed that the deficiency of rare earth elements in the diet of animals causes a disruption in their body metabolism of this group of elements in the nervous and endocrine systems, which is accompanied by specific hormonal stress. The state of stress forces animals to look for ways to minimize the problem that has arisen. They solve it by consuming mineral or organomineral sorbents (mainly clay rocks and peat soils) relatively enriched with rare earth elements in places where they are slightly saline, mainly with carbonate salts of calcium, magnesium and sodium. Such salts create an alkaline environment favorable for the formation of clay mineral sorbents that are capable of accumulating ions of rare earth elements. In addition, sodium salts, by affecting the central nervous system, help animals alleviate the state of stress.

Data obtained by the authors show that the background level of the rare-earth element (REE) content in the surface waters of southern Russian Far East is irregular and varies from 0.1 to 1.3 μg/l. The highest concentration of REE (0.48–1.3 μg/l) is characteristic for the rivers of Eastern Sikhote-Alin and Central Sikhote-Alin, catchment areas which are situated within the Sikhote-Alin volcanic belt. The lowest REE concentration was noted in the waters of Western Sikhote-Alin (0.09 μg/l). The profile of REE distribution in fresh waters of different areas of the region is uniform and is characterized with the deficit of Ce and enrichment of medium group REE.