Aleksei Nikolavich Makhinov

This paper explores the impact of global climate change and basin-wide urbanization on the hydrochemical cycles of the Amur River, viewed through the lens of channel processes during extreme flood events. Despite significant advancements in understanding floods as a primary driver of the rivers hydrochemical regime, a comprehensive synthesis of research in this field has been lacking. Our analysis demonstrates a clear upward trend in regional climate shifts: from 1989 to 2024, the average annual air temperature rose by 1.3℃, with a total increase of 2.0–2.1℃ since the beginning of instrumental records. This warming has fundamentally altered the frequency of high-magnitude floods, accelerated channel transformations, and reshaped geochemical cycles within the river discharge. The Amur River is characterized by a unique hydrological regime. Recurring catastrophic floods in recent years (2013, 2019–2021) demonstrate the impact of hydrodynamic factors on the dispersion of contaminants. Turbulence during peak discharge activates resuspension processes, leading to the re-entry of heavy metals from benthic sediments into the water column, effectively turning the riverbed from a sink into a major pollution source. The study details the mechanisms of channel processes and the periodicity of geochemical cycles, establishing a definitive link between these phenomena. Particular emphasis is placed on the transboundary transport of pollutants from major industrial hubs in China and the Russian Federation, as well as the role of background chemical compounds. Large tributaries of the Sungari and Ussuri rivers are the main sources of anthropogenic trace elements in the Amur. Urbanization contributes to the local accumulation of lead and cadmium in bottom sediments of coastal areas, creating zones of potential secondary pollution. We describe the migration pathways of heavy metals, finding that their concentration increases 2.5–3.5 times during flood stages. Furthermore, flow turbulence and channel dynamics intensify chemical interactions, creating pronounced spatiotemporal heterogeneity in geochemical fluxes. The paper assesses the synergistic effect of anthropogenic pressure and natural factors on water quality, while analyzing how temperature and chemical variables (metal compounds, organic matter) influence the self-purification capacity of aquatic ecosystems.

The Okhotsk Region holds a leading position in the Russian mineral resource sector for gold and platinum mining. This study was conducted at gold and platinum mining sites in the Ayano-Maysky district of the Khabarovsk Territory (Tas-Yuryakh, Ryabinovy, Muktana, and Konder). Mining operations in the extreme natural conditions of the Northern Khabarovsk Territory significantly impact the state of local soils and water bodies. Open-pit mining and traditional processing technologies lead to the accumulation of industrial waste and the intensification of exogenous processes in disturbed areas, which serve as the primary causes of soil and surface water pollution. Waste heaps, tailings facilities containing liquid pulp, and settling ponds pose the greatest environmental hazards during mineral extraction. The interaction of decomposition products with under-oxidized minerals contributes to the enrichment of wastewater. During periods of heavy rainfall, turbid enriched solutions are washed into the soil and surface watercourses via sheet erosion processes. Even after decommissioning, these sites remain long-term sources of local pollution for natural ecosystems, particularly affecting soil cover and natural waters. The technological methods used in mining involve the release of various heavy metal compounds into the environment, especially into surface soil layers and water bodies. This article examines the distribution patterns of chemical elements (Fe, Cu, Zn, S, Pb, Cd, Co, Ni) at various distances from operating enterprises and the conditions of their concentration depending on environmental factors. High concentrations of nickel and zinc, as well as elevated lead content, were detected in soil profiles, resulting from the dissolution of chemical compounds in ore-bearing rocks and the activation of exogenous processes. The distribution of element anomaly levels in soils revealed that the migration of chemical compounds within the soil space and subsequent soil pollution manifest at a distance of up to 300–500 m from waste heaps and tailings facilities. Elevated levels of iron, aluminum, manganese, and copper were also noted in watercourses. Finally, the core principles have been formulated for an environmentally adapted land-use regime tailored to the mountainous conditions of the northern Russian Far East.

The mechanisms underlying the breakdown of a landslide body from the slope of the Bureya Reservoir on December 11, 2018, and the formation of an ice tsunami are considered. A model of pulsed disturbance of a water mass, wave dynamics, and processes of its breakdown into a series of waves with a maximum splash height of 90 m are described. On the lower part of the slopes are taiga soils with high ice content, dissipated by ice to the extent that cryogenic processes do not have a cementing effect on soil. The unconsolidated structure and high porosity of the profile were the reasons for their poor resistance to tsunami impacts. The washout of a large mass of organomineral material by the back wave activated the processes of dissolution of chemical compounds of various natures. The uneven distribution of heavy metals along the shores of the reservoir is due to the varying intensity of the processes of crushing of the landslide body and resuspension of fine fractions from its underwater part. The ability of polyvalent cations (Fe^{+2, +3}, Mn⁺², Co⁺², Ni⁺², Cu⁺², Zn⁺², Cd⁺², Pb⁺²) to form chelate complexes with low-molecular organic substances contributed to their presence in a dissolved state and water pollution at the mouth of the Sredny Sandar River and adjacent areas of the reservoir.

Climate-driven hydrological extremes and anthropogenic interventions are increasingly altering streamflow regimes worldwide. While prior studies have explored climate or regulation effects separately, few have integrated multiple teleconnection indices and reservoir chronologies within a cross-basin comparative framework. This study addresses this gap by assessing long-term streamflow nonstationarity and its drivers at two key stations—Khabarovsk on the Amur River and Datong on the Yangtze River—representing distinct hydroclimatic settings. We utilized monthly discharge records, meteorological data, and large-scale climate indices to apply trend analysis, wavelet transform, percentile-based extreme diagnostics, lagged random forest regression, and slope-based attribution. The results show that Khabarovsk experienced an increase in winter baseflow from 513 to 1335 m³/s and a notable reduction in seasonal discharge contrast, primarily driven by temperature and cold-region reservoir regulation. In contrast, Datong displayed increased discharge extremes, with flood discharges increasing by +71.9 m³/s/year, equivalent to approximately 0.12% of the mean flood discharge annually, and low discharges by +24.2 m³/s/year in recent decades, shaped by both climate variability and large-scale hydropower infrastructure. Random forest models identified temperature and precipitation as short-term drivers, with ENSO-related indices showing lagged impacts on streamflow variability. Attribution analysis indicated that Khabarovsk is primarily shaped by cold-region reservoir operations in conjunction with temperature-driven snowmelt dynamics, while Datong reflects a combined influence of both climate variability and regulation. These insights may provide guidance for climate-responsive reservoir scheduling and basin-specific regulation strategies, supporting the development of integrated frameworks for adaptive water management under climate change.

It has been established that the formation of the relief of the Lower Amur region is due to the long history, differentiated tectonic movements, climatic features, and a complex permafrost pattern. Despite the low elevations of the mountain ridge tops, numerous traces of Quaternary glaciation, relict permafrost forms, and active manifestation of modern cryogenic processes on the highest peaks of the mountains have been found there for the first time. Data on the distribution and occurrence of permafrost strata within the Udyl’-Kizi and Evoron-Chukchagir lowlands point to their relict nature. Specific features of erosion-accumulative processes of mountain taiga rivers in the monsoon climate zone, caused by significant seasonal unevenness of the runoff, have been revealed. It is shown that the Amur River bed, crossing vast lowlands, forms complex floodplain-channel branches, in which the water flow and sediment deposits are being constantly redistributed between the branches. An assessment is given of the role of uneven floodplain sedimentation played in the emergence of various forms of mesorelief. The features of the formation of the floodplain and floodplain lakes under conditions of a deficit of traction load within the Lower Amur Lowland are revealed.

На основе анализа «хода путешествия» и карт, опубликованных в книге А.Ф. Миддендорфа «Путешествие на Север и Восток Сибири», приводится краткое описание маршрута научной экспедиции А.Ф. Миддендорфа в 1844–1845 гг. по территории современных Хабаровского края и Амурской области и представлены физико-географические, в том числе зоогеографические открытия. Указанные в этих материалах даты и точные привязки местности позволяют определить места исследований и скорость передвижения экспедиции. А.Ф. Миддендорфом впервые было дано научное описание нескольких горных хребтов, рек, долин, а также морских берегов, особенностей растительного и животного мира. Составлена карта Станового хребта и сопредельных территорий бассейнов рек Алдан и Амур, а также юго-западного побережья Охотского моря. Особую ценность представляют данные наблюдений за различными природными процессами, обусловленными географическим положением исследуемой территории. Впервые описан карстовый рельеф плато Мар-Кюель и выявлены особенности морфологии русел и водного режима рек в его пределах. Особую ценность представляют данные о строении наледей и их влиянии на прилегающие территории. Впервые получены сведения о строении и динамике морских берегов и устьев впадающих в Охотское море рек в условиях высоких приливов. Проведено комплексное обследование острова Медвежий и двух островов Шантарского архипелага. Выявлена роль древесных плотин в формировании речных русел. Впервые указаны основные особенности животного мира региона, выявлены ареалы некоторых видов животных. Приводятся уникальные сведения о жизни и быте коренных народов обследованной территории. Результаты экспедиции имели большое фундаментальное географическое и биологическое, а также геополитическое значение и во многом позволили принять впоследствии важное решение о присоединении значительной части бассейна р. Амур к Российской империи. Based on an analysis of the “progress of the journey” and maps in the original source (A.F. Middendorf, Travel to the North and East of Siberia, part 1, 2004, part 2, 2006), a brief description of the route of Middendorf A.F.’s scientific expedition in 1844-45 across the territory of modern Khabarovsk Territory and Amur Region is given. Physical and geographical discoveries, including zoo-geographical ones, are presented. The dates and precise location references indicated in this research report make it possible to determine the research sites and the speed of the expedition’s movement. A.F. Middendorf was the first to give a scientific description of several mountain ranges, rivers, valleys, as well as seashores, features of the flora and fauna. A map of the Stanovoy Range and adjacent territories of the Aldan Amur river basins, as well as the southwestern coast of the Sea of ​​Okhotsk, had been compiled. Of particular value are observational data on various natural processes determined by the geographical location of the study area. The karst relief of the Mar-Kuel plateau was described for the first time and the features of the morphology of channels and the water regime of rivers within its boundaries were identified. Of particular value are data on the structure of aufeis and their impact on adjacent areas as well. For the first time, information had been obtained on the structure and dynamics of the sea coasts and mouths of rivers flowing into the Sea of ​​Okhotsk under conditions of high tides. A comprehensive survey of Medvezhiy Island and two islands of the Shantar archipelago was carried out. The role of wood dams in the formation of river channels had been revealed. Particular attention in the research was paid to the patterns of vegetation distribution depending on natural conditions, and the reason for its variability in the mountains was revealed. For the first time, the main features of the region’s fauna were indicated, and the ranges of some animal species were identified. The results of the expedition were of fundamental geographical and biological, as well as geopolitical significance and in many ways made it possible to subsequently make an important decision to annex a significant part of the Amur basin to the Russian Empire.

The relevance of the research is due to the poor study of permafrost-geoecological conditions and the everincreasing role of their negative impacts on modern economic development of the Lower Amur region. It is shown that one of the significant limiting factors of development is permafrost and dangerous cryogenic processes in the region, their activation under global warming. The object of the research is permafrost of the plain and mountainous territories of the Lower Amur region. The subject is the limiting factors of economic development of the Lower Amur region, caused by dangerous manifestations of cryogenic processes in various geomorphological conditions. The purpose and objectives of the research are to assess the state of permafrost and dangerous cryogenic processes on various landforms and their impact on modern and prospective objects of logistics infrastructure during the development of plains and adjacent territories. Methods and methodology are as follows: based on the analysis of available maps, ESRI ArcGis Imagery satellite images and field work data, the main forms of macro-, meso- and microrelief and the cryogenic processes associated with them are identified. Based on the geomorphological confinement of hazardous cryogenic processes to certain relief forms, natural areas of specific economic development are identified. To determine the degree of hazardous cryogenic processes impact in areas of natural areas of specific economic development, the main factors differentiating natural areas by permafrost-geoecological conditions and permafrost-geoecological areas by the degree of favorability of economic development are identified. The practical use of the research results is shown in the analysis of the route of the existing winter road “named after P. Osipenko – Tugur”, located within the Lower Amur region

Effects of floods on chemical pollution of floodplain soils and abiotic stress on plants were assessed. The presented research has revealed that hydrological conditions (flooding depth, temperature regime of flood waters and flood duration) affect the survival of plant species. The resulting hydrological regime and high concentrations of pollutants in flood waters cause abiotic stress for floodplain vascular plants. The intensification of riverbed processes reduces the stability of the habitats of meadow complexes, disrupts the ratio of their species composition and affects changes in the structure of the vegetation cover. Consequences of such changes are still poorly understood. The concentration of soluble compounds of heavy metals in soils and their absorption by plant roots has a decisive influence on mechanisms of regulation of enzymes and metabolism of vascular plants. Emerging toxicity effect contributes to the development of abiotic stress on certain types of plant communities (phenomenon chlorosis). Plants affected by heavy metals have shorter root and stem lengths. It is emphasized that concentrations of Fe³⁽²⁾⁺, Zn ²⁽¹⁾⁺ and Cu²⁽¹⁾⁺ in soil solutions identify the specificity of plant responses to abiotic stress. Mechanisms and interrelationships of these events are described. Despite significant progress in understanding of many aspects of floodings as an abiotic stressor no synthesis and analysis of the obtained data have been made so far. This study discusses the toxic effects caused by various heavy metals in plants. This is our first attempt to contribute to such research attempts.

Information on the history of the creation and development of the Institute of Water and Environmental Problems, Far Eastern Branch, Russian Academy of Sciences (IWEP FEB RAS), is provided. It is one of the oldest scientific institutions of the Russian Academy of Sciences in the Far East. Information on the main scientific areas of research related to the study of the patterns of formation of land waters and the dynamics of ecosystems for the purpose of rational use of biological resources is summarized. The main scientific tasks of the institute’s laboratories: hydrology and hydrogeology, hydroecology and biogeochemistry, vegetation ecology, animal ecology, soil ecology, optimization of regional environmental management, and swamp and forest resources are described, and the most important results of research, mainly over the past 10 years, are presented. Characteristics of the scientific bases located on the banks of the Amur and in the foothills of the Sikhote-Alin and the Interregional Center for Environmental Monitoring Center for Collective Use are given. Analytical studies of the state of the environment and monitoring of biogeochemical processes are carried out in this center. Brief information on the institute’s herbarium (which has an International Herbarium Index (KHA)), where rare and endangered plant species in the region can be found, is given. The areas of expeditionary research carried out in recent years are pointed out, and information on the most important applied research commissioned by various organizations is given. In this paper, we especially noted the research carried out in connection with the need to quickly assess and solve particularly unexpected acute environmental problems that arise from dangerous manifestations of natural processes in the region. Information on the international scientific contacts of the institute, the participation of employees in teaching activities at universities, and work with students in schools in Khabarovsk krai is presented.

Antibiotics have attracted global attention due to the ecological risks to environment. In this paper, solid-phase extraction and ultra-performance liquid chromatography triple quadrupole mass spectrometry (LC–MS/MS) were utilized to analyze the fugitive characteristics of 10 antibiotics of sulfonamides (sulfadiazine, sulfamethazine, sulfadimidine, sulfathiazole, sulfapyridine, sulfamethoxazole) and tetracyclines (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in the coastal waters and surfece sediments of the Yangtze River Estuary and the ecological risks of antibiotics in water were estimated using ecological risk assessment method. The results have showed that 7 of the 10 antibiotics were detected in the water, with total concentrations ranging from 0.652 to 434.47 ng/L. 8 antibiotics were detected in the sediment, with total concentrations ranging from 0.091 to 499.23 ng/g. The main antibiotic species detected in the sediment and water varied seasonally. Higher concentrations in spatially distributed areas where rivers meet and where human activities have a more significant impact. The ecological risks were found to be higher in spring and autumn than those in winter and summer. Spatial variation in individual microbial communities was not evident in the sediments. The relationship between antibiotics and microorganisms in the environment was predominantly positive. Physical and chemical factors were significantly correlated for both antibiotics and microbial communities. This study can provide research ideas for other types of antibiotics and provide a basis for the prevention of antimicrobial resistance (AMR).