This article presents the significant findings of research in the field of Earth Science in the Republic of Sakha (Yakutia). The main focus of future research includes the investigation of the geological structure and evolution of the Earth’s crust in Yakutia, exploration of ore-forming systems for strategic mineral types, identification of oil source rocks, and the discovery of natural naphthide accumulations. These findings serve as a fundamental basis for enhancing the level of geological exploration of the subsurface, development of advanced technologies for geological exploration and prospecting in specific geological settings. It is essential to monitor the natural environment and climate of the region, establish a comprehensive system for observing, analyzing, and forecasting the response of ecosystem components to both natural and anthropogenic changes, and develop technologies for the restoration of disturbed areas. The recognition of the importance of ensuring a sufficient number of highly qualified staff members is also acknowledged.

An analysis of the groundwater and permafrost interaction is presented in this study. The analysis is based on an extensive review of scientific literature and our own investigations. The article specifically examines the significant impact of phase changes between liquid and solid states in groundwater, including the freezing of aquifers and the thawing of ice-rich permafrost. The discussion highlights the essential characteristics of groundwater interactions with frozen ground in permafrost regions.

A few localities world wide are known to have remainsof dinosaurs andothervertebrate animalsthat livedin thepolarlatitude region during the Mesozoic era. The Teete locality in the Vilyui River Basin, Yakutia (Russia) is one of the few known dinosaur localities in the Northern Hemisphere. In 1988, 2002–2012 school children participated in asearch for Early Cretaceous dinosaurs and other vertebrates at the Teete locality, and teeth and bones were collected and briefly described.Additional vertebrate remains, including lizards, salamanders, choristoderes, and tritylodonts, were discovered in Early Cretaceous sediments in Yakutia, which expanded the number of known locations wherethese animals lived in polar regions. In 2017–2019 comprehensive paleontological studies were conducted in Teete,during which time fragmentary skeletal elements and teeth of various dinosaur groups, as wellas bone elements from other vertebrates, were collected using surface collection methods. This study also yielded new genera of Mesozoic mammaliforms,mammals,and salamanders.The presence of astem salamander, basalturtle, and other Jurassic relicts in the Early Cretaceous vertebrate fauna of Teete suggests that the area was a refugium for these animals during that time. Further study of the Teete locality is expected to lead to the description of new dinosaur and other vertebrate taxa, as wellas to theacquisitionof new data on the adaptation of these animals to circumpolar conditions.

The petrographic and geochemical characteristics of the Mesozoic igneous rocks of the Mikhailovsky massif, including the sills and dikes of the Evotinsky ore district located in the central part of the Nimnyr terrane of the Aldan-Stanovoy shield, were examined. This study revealed for the first time that the Mikhailovsky Massif is composed of  quartz monzonites, while the sills and dikes are composed of quartz syenites. These rocks are geochemically close to the shoshonite-latite series of island arc rocks and are enriched in LREE and depleted in HREE, characterized by aweak negative Eu-anomaly. The sequence of magmatism development in the Mesozoic has been established: the formation of rocks of the Mikhailovsky massif and most small bodies occurred in the post-collision period, followed by the intrusion of quartzsyenite dike bodies in theanorogenicstages of territorial development.The study suggeststhat all the studied igneous rocks of the northeastern part of the Evotinsky region are characterized by a duality of geochemical composition,which indicates either intense mantle-crustal interactionor the existence of two sources of both mantle and crustal originat that time.

This article presents an examination of research conducted on the flora and fauna of Yakutia, with a focus on key findings and outcomes. Throughout the past decades, new discoveries have been made regarding the diversity, distribution, biology, and ecology of the region’s plant and animal life, and an updated inventory of species has been conducted utilizing modern systematic principles and new scientific knowledge.

The main patterns of soil cover development in Yakutia and the morphogenetic features of permafrost soils were identified in the first few years of the 20th century by researchers representing the scientific school of V.V. Dokuchaev. The soil scientists of the Complex Expedition of the USSR Academy of Sciences between 1925 and 1930 significantly broadened the scope of soil-geographical research. The Yakut School of Soil Science emerged during the post war period. The works of Yakut scientists on the study of permafrost soils throughout the republic and soil maps of various scales have earned recognition from soil scientists of the Soviet Union. In the 1990s, the modern era of soil science development in Yakutia began on an international scale.

This article examines thehistorical andcurrent state of the subcivilization in the Russiansector of the Arcticand Subarctic, which is rooted in reindeer husbandry and other forms of environmental-based traditional northern environental management.The preservation anddevelopmentof this subcivilization in modern conditionsis closely linked to the organizational and economic modernization, as well as the technological re-equipment, of all sectors of tradi tional Northern Natural Resource Management. Examples include the biotechnological advancement of traditionalenvironmental managementin the North,which enhances the economic viabilityof its industries while improving the quality of life in the region. Another key resource in Northeast Eurasia is the natural cold, which is a unique and fundamental feature of thecoldest inhabited region ontheplanetwith the lowest temperature and most stable permafrost. The development of modern technologies for preserving permafrostin the conditions of climate change and increased economic activity in the Arctic has the potential to significantly impact the development of subcivilization in the Northeast of Russia.

This study presents the results of research on the climatic signal of radial growth of Siberian larch (Larix cajanderi Mayr.) in the Omoloy River Basin, (north-eastYakutia). Tree-ring width chronologies were obtained from three sites  located in the valley complexes of subarctic tundra and forest-tundra ecotone, with chronologies spanning up to 498 years. Comparative analysis of radial growth dynamics and its statistical parameters indicated similar variability patterns within the study region. Dendroclimatic analysis revealed that the primary limiting factor determining the magnitude of radial growth in Siberianlarch is the air temperature during the first half of the growing season. Increasing temperatures have led to an increased role of precipitation and changes in the strength of growth-temperature correlations, especially in northern sites.This study highlights the potential for dendroclimatic and dendroecological researchin northern Yakutia.

The majority of Russia’s oil and gas-producing regions are situated in the northern part of Western Siberia, where sandy podzolic soils are prevalent. Due to the low buffering capacity of these soils and the severe Arctic climate, the conventional method of bioremediation for removing oil contamination is not effective. This study, for the first time, explores the potential of adsorptive bioremediation for purifying oil-polluted gley-podzolic soil. This approach involves introducing natural sorbents of various classes before soil treatment through bioremediation. The optimal conditions for soil treatment can be determined using the express phytotests based on white clover ( Trifolium repens ) seed germination. The results indicate that under the best conditions, which involve adding 2 % mixed sorbent based on granulated activated carbon (GAC) and diatomite (4:1) or Spilsorb, it is possible to minimize soil phytotoxicity after 2-3 warm seasons and reduce the content of total petroleum hydrocarbons to the permissible residual oil content (≤5 g/kg) established in the territory of the Khanty-Mansiysk Autonomous Okrug for recultivated agricultural soils. Moreover, other sorbents, such as peat, GAC, vermiculite, zeolite, and diatomite, can be used to reduce phytotoxicity to <33 %, allowing for additional soil decontamination through phytoremediation.

In the context of intensive industrial development in the Republic of Sakha (Yakutia), the issue of restoring technogenically disturbed areas is becoming increasingly relevant. Technogenic landscapes formed during the extraction of mineral deposits often have negative effects on the environment, and severe environmental conditions hinder the restoration of ecosystems affected by industrial activities. This study synthesized the long-term research results of scientists from the Research Institute of Applied Ecology of the North named after Prof., Dr. Savvinov (NEFU) on the study of succession and soil restoration processes in post-technogenic landscapes of placer deposits in the basins of the Anabar River and the Aldan River, as well as at the diamond and coal ore deposits in the Mirninsky, Aldansky and Neryungrinsky regions of Yakutia. Our study demonstrated that the effective restoration of technogenically disturbed landscapes is relevant to the use of seeds and planting materials from local flora in the biological stage of reclamation. On the dumps of ore deposits composed of rocks that are slowly weathered under hypergenesis conditions, effective restoration can be achieved only with the formation of technogenic soil. Due to the deficit of (decipher) PPP and (decipher)PSP, it is necessary to create a technology for the biological reclamation of disturbed lands with the use of alternative materials.

Thein terim results of the first year of the project,funded by theRussian Science Foundation(RSF), are presented. The study focuses  on the species  diversity of  the symbiofauna of  domestic  animals bred  in Yakutia.A total  of  1,760 samples  were  collected  from  various  types of  domestic  animals and analyzed.  The research identified  and described  98species of endobiontsin ruminantsand25species in horses (based on2breedtypesof theYakutbreed). Additionally, severalr are  species  of  ciliates  were  discovered during  the study. Notably, this  study is  the first to  compare the diversity  of Yakut aboriginal cattle with  crossbred  and Simmental cattle. The findings reveal  that  the endemic Yakut cow, bred under conditions of poor, low-nutrient feeding during along winter period, has developed an adaptive functional feature, such  as  a diverse  symbiont  fauna of  protozoa,  to  facilitate  the complete  breakdown and absorption of  limited nutrients in  the feed.  Furthermore, the study found no significant differences in  symbiofauna between the Even and Chukotka reindeer breeds, which differ in their breeding zones.

In  the Even breed of  deer,  a total  of  13 species  were  identified, while in  the Chukchi deer,  11  species  from  six genera were  found.  In  domestic  sheep and hybrids (which  are half  domestic  sheep and half  wild  bighorn sheep),  12 ciliate species were identified, buttheir diversity did not differ. In theYakuthorsebreed,15 species of endobiont ciliates were identified, of  which 11  are indigenous  and 14 are of  the Yan type. This  research provides the first data  on the endobionts of herd horses of the Yanatype of the Yakutbreed. Thestudied populations of herd horses were characterized by are latively high level of end obiontdiversity. The species similarity between two populations of the Yakut horse breed, bred  in  different geographical zones,  was demonstrated. This  research has identified  the symbiotic  fauna of  domestic animals and established a connection between the species  composition  of  the symbiotic  fauna and the habitat  of  the animals, including their social behavior.

An overview of the research in the field of Northern and Arctic Materials sciences is provided, including the design and safe operation of materials for complex technical systems in extreme environments. The discussion covers the fundamental principles of material design, including structure at different levels of organization and scales, and the development of theoretical and numerical models. Additionally, the optimal ratios of components and technological stages are discussed to obtain specific properties such as corrosion resistance, wear, cold and frost resistance, strength, and plasticity. These efforts aim to ensure the reliable operation and resource efficiency of machines and structures in harsh arctic and subarctic conditions.

The main mathematical models used to address issues related to global climate change and human impact on the natural systems of the northern regions are discussed. These models were employed to analyze the effects of emergency situations and develop regional decision-making systems for prevention and mitigation. Moreover, these models can be utilized to establish automated networks for monitoring carbon flows, forecasting climate change, identifying sources of pollution, and describing the processes by which pollution spreads in the atmosphere, soil, or water bodies. These efforts aim to address the environmental damage and mitigate the negative impacts of human activity on the natural world.