The article presents new data on the burial ritual of the Eneolithic population of the Eastern Europe's forest belt obtained during the analysis of materials from a single pit grave at Derevyannoe XI. Accompanying grave goods during the inhumation of the deceased (his bone remains did not survive) included an original set of amber jewellery similar to the items found in Sarnate-type dwellings at the Sarnate site dated by the radiocarbon method (southeastern part of the Baltic Sea coast, Latvia). This evidence along with considering other analogies gives grounds to attribute the burial in question to the late 4th millennium BC. For the first time in the burial rite of the Eneolithic population in the region, it was possible to identify the use of very small chips from tools, including used ones, and their blanks made of imported flint and local metatuff. The discovery of a high concentration of arsenic in the grave made it possible to determine a microregion in the Onega Lake basin, where the deceased lived for a long time.

A ca. 12,700 year-long pollen and diatom record, as well as data on lithology, geochemistry, and grain size were obtained from two sediment cores retrieved in the southwest part of Lake Ladoga. Changes in phosphorus content during the Holocene were recorded from this sequence dated by the radiocarbon method. An increase in phosphorus, loss-on-ignition and the Fe/Mn ratio was recorded during the climatic optimum of the Holocene ca. 7500–7250 cal yr BP. At the same time, pollen data showed the spread of broad-leaved forests. The peak in phosphorus in the upper part of the core associated with anthropogenic activities is smaller to the peak corresponding to the Holocene climatic optimum. This may indicate that climatic factors affect the ecosystems of large lakes more significantly than anthropogenic ones. According to our new pollen data, first human impact is recorded in Lake Ladoga sediments ca. 2580 cal yr BP.

The first data on the composition of pollen spectra of subrecent lake sediments were obtained from surface samples of Lake Vodonosnoye and Lake Chernyaevskoye sediments on Zhizhgin Island, which is located in the southern part of the White Sea. Currently, woody vegetation on the island grows in small areas and consists mainly of shrubby birch and willow and oppressed pine. The pollen spectra generally reflect the modern vegetation of the island. The pollen spectra include pollen of tree species and grasses, which occupy large areas of open meadows and wetlands. Picea and Pinus pollen found in significant quantities is partly introduced. Abies and Tilia pollen are also likely introduced. The results of pollen analysis of surface samples will be used for pollen analysis of sediment sequences of the investigated lakes, which will allow for correct interpretation of the data obtained and a more correct reconstruction of the island’s vegetation in the past.

A connection between the dynamics of the distribution of macrophytes in lakes isolated from a large lake or sea with changes in the coastlines of large reservoirs has been established. In the process, there are a change in the composition of macrophytes or their decrease at different stages in the coastlines change of lakes and seas. The conclusions were based on a multi-proxy paleolimnological study of the Lake Ladoga’ island lakes and lakes of the Kurgalsky Peninsula on the Gulf of Finland southern coast of the of the Baltic Sea.

Lake sediment sequences of the small Lake Nadbannoye on Anzer Island (Solovetsky Archipelago, White Sea) have been analyzed. Lake located at the highest elevation of 20–21.5 m a. s. l. relative to other lakes studied on the island. Based on the results of pollen analysis, the dynamics of vegetation from the Late Glacial period and during the Holocene was traced. In this research, the special attention is paid to the dynamics of tree species, which are an important component of the vegetation cover in the study region. Changes in the composition of tree species here are the basis for the identification of pollen zones. Throughout the entire studied period, the forest-forming species was birch, with pine being of secondary importance. A low content of spruce was noted, which is not typical for other sites of the White Sea region. Broad-leaved species clearly mark the boundaries of the Atlantic period. Anthropogenic influence has been recorded since the Subboreal period, which is confirmed by the dynamics of tree species, as a result of deforestation as a result of human activity. Radiocarbon dating confirms the pollen data.

Macrophytes are an excellent indicator of the lake’s local conditions and state changes. However, their pollen are rarely used in paleoreconstructions due to low occurrence and poor preservation in lake sediments. In the course of paleolimnological research in recent years, we have studied five lakes located on the Valaam Island in the northern part of Lake Ladoga, Russia. All lakes, placed at different absolute altitudes above the sea level, were part of Lake Ladoga and became isolated during its last regression. In this study, we present the dynamics of macrophyte pollen in the Late Holocene on the example of two of them. The research material is the lake sediments for pollen analysis. We have obtained data on changes in the macrophyte diversity, abundance, and distribution. We have reconstructed the stages of lake development due to the transgressive–regressive phases of Lake Ladoga. The first stage was associated with the transgression when the Ladoga waters covered the study area and the macrophyte distribution was low. In the second stage, at the end of the Sub-boreal period, Ladoga regression occurred and caused the beginning of the lakes’ isolation. The temporary disappearance of macrophyte pollen indicates this period. As the lakes gradually lost their connection with Lake Ladoga, various macrophytes began to repopulate them. Since the isolation, the distribution and changes of aquatic vegetation were determined by natural succession and human influence. Now these are shallow overgrown lakes. The results allowed us to refine the island lakes isolation stages from Lake Ladoga and confirm the significance of macrophyte pollen in paleolimnological studies by revealing the correlation between their dynamics and the stages of lake development.

A 23.5 m deep borehole was drilled on the dried bed of the Aral Sea 9 km south of the former Barsakelmes Island. At a depth of 21.3 m, the borehole penetrated Paleogene bedrock. In the interval 21.3 - 15.2 m the conditions of a shallow freshwater reservoir at a considerable distance from the flowing rivers (deltaic channels of the Syr Darya River) - the first phase of filling of the Aral Basin with river water - were reconstructed. It has been preliminary attributed by three 14C AMS dates to the time about 23-25 thousand years BP. Above 15.2 m of the section the conditions become even more shallow, starting from 12.0 m of the section - brackish-water. The upper 10.5 m of the section correlates with the sediments of the modern geological phase of the Aral Sea development studied in detail in the same area by Burr et al. (2019), the beginning of which was estimated at 17.6 thousand BP. The new data obtained indicate an earlier appearance of the modern Aral Sea, which originated as a shallow freshwater body.

In August 2023, a study of aquatic vascular plant communities was carried out in Lakes Beloe and Lipovskoe, located on the territory of the Kurgalsky State Nature Reserve of regional importance. The species composition and spatial distribution of macrophyte communities were recorded using the standard phytolittoral mapping method. Changes in the distribution of macrophytes by depth were studied on transects with scuba diving. In an oligotrophic Lake Beloe, submerged plant communities are formed by Lobelia dortmanna with Isoëtes echinospora, I. lacustris, Myriophyllum alterniflorum and Littorella uniflora. The depth of distribution of Lobelia communities in Lake Beloe reaches 4 m. Helophyte communities are dominated by Phragmites australis with Scirpus lacustris and Typha latifolia. Submerged hydrophytes exceed the area of helophytes by 4 times. In a brackish Lake Lipovskoe, both common freshwater species and species typical of saltwater bodies occur. Helophyte communities consist predominantly of Phragmites australis with Bolboschoenus maritimus and Scirpus lacustris. Submerged communities are composed of Potamogeton perfoliatus, P. pectinatus, Myriophyllum sibiricum, Batrachium marinum and Najas marina. Depth of distribution of submerged macrophytes in Lake Lipovskoe reaches 3.5 m. In Lake Lipovskoe, the area of submerged hydrophytes exceeds the area of helophytes by only 1.7 times. Gently sloping shores and high water transparency contribute to a more pronounced dominance of submerged plants in Lake Beloe compared to Lake Lipovskoe. In Lake Beloe, the dominance of Lobelia communities corresponds to oligotrophic conditions. In Lake Lipovskoe, the widespread distribution of eutraphent (Potamogeton pectinatus, Najas marina) and mesotraphent (Potamogeton perfoliatus) species indicate meso-eutrophic status of the lake.

In this study we investigate the dynamics of Cladocera subfossil assemblages (taphocoenoses) during the formation of the cascade of three lakes located on the island of Lunkulansaari in the northeastern part of Lake Ladoga in the late Holocene. Since the last regression of Lake Ladoga and the formation of the lake cascade, Cladocera subfossil assemblages began to accumulate in bottom sediments. Their species structure was alternately dominated by species typical for aquatic vegetation in the littoral zone or species that prefer to live in open water. The data obtained allowed to reconstruct changes in lakes’ water levels and clarify the stages of their development, previously revealed on the basis of pollen spectra of aquatic vegetation.

Late Glacial – Holocene sedimentary record has been obtained from a lake basin at the north of East-European Plain, and AMS14C-dated. Coring results were coupled with the ground penetrating radar (GPR) survey, which enabled for the sedimentary sequences’ chronology to be upscaled for the whole basin and beyond. A prominent peat layer (presumably of Allerød age) has been suggested as a marking horizon to correlate with the Late Glacial lacustrine dynamics in the area. Laminated silt with low organic matter content (of the Younger Dryas age), underlain by sandy silt deposits were discovered both from the boreholes and via the geophysical survey. The lower surface of these strata forms wavy and hummocky bottom relief. Organic muds (accumulated in the Holocene) cover the mineral deposits equally.

This monograph is dedicated to the 80th anniversary of the Institute of Limnology of the Russian Academy of Sciences. The most important stages of development of the Institute are described. The main directions of research conducted at present are presented, as well as the most important scientific and applied results obtained during the last decades. They include the assessment of modern water resources of Russia and the world, advances in the study of hydrological, hydrochemical, hydrobiological and geological-geomorphological processes in the largest freshwater body of water in Europe - Lake Ladoga as well as in small lakes of the Northwest and the Arctic zone of Russia, successes of paleolimnological research. In addition, the results of studies on metabolomics of aquatic organisms, causes of toxic "blooming" of water and development of ways to combat it, evaluation of water pollution by microplastics and development of methods for mathematical modeling of heat and mass transfer processes in the "watershed-watercourse-water body" system are presented. Materials contained in the book can be of interest for the general scientific community engaged in the issues of study, protection and rational use of water bodies.

The multi-proxy study of the lowermost part of the sediment sequence of Lake Kanozero (south-western part of the Kola Peninsula, ca. 53 m a.s.l.) revealed the evidences for marine waters penetration into the basin during the earliest stage of its evolution. The diatom analysis inferred the conditions of a large brackish-water basin. Sediments composition and very low organic content also supported large-basin and low-productivity environments. Based on the pollen study, this stage covers a cooling period preceding the Allerød (tentatively assigned to the Older Dryas) and the onset of the Allerød. Periglacial vegetation typical of the cold and dry climate prevailed in the area for the most of the period. The subsequent transition to the freshwater conditions inferred from the diatom study took place in the Allerød, according to the pollen data. Except for a minor decrease in the fine sand fraction, no other corresponding changes were observed in the sediment record suggesting no major shifts in sedimentary environments. In the late Allerød and throughout the Younger Dryas, Lake Kanozero remained a large, low-productive freshwater basin. Our results indicate that ice-free conditions with aquatic sedimentation in the Kanozero depression had already existed in the Older Dryas. This assumes earlier deglaciation of the study area than it was previously thought. The study also suggests that brackish conditions in the White Sea basin established earlier than reported before. While the previous studies found no signals of marine transgression above ca. 41 m a.s.l., our results indicate that the local marine limit in the study area exceeds ca. 53 m a.s.l.

The article presents the results of studying the subrecent pollen spectra (SPS) and modern aquatic vegetation of four small lakes on Valaam Island (Lake Ladoga) – Germanovskoye, Zimnyakovskoye, Antonievskoye, and Vitalievskoye. We have established that the lakes are humus-rich reservoirs slightly overgrown with typical aquatic vegetation. The moss Fontinalis antipyretica Hedw. is the dominant species among submerged hydrophytes for lakes Germanovskoye, Antonievskoye, and Vitalievskoye. The dominant floating hydrophytes and helophytes are Nuphar lutea (L.) Smith for lakes Germanovskoye and Zimnyakovskoye; Nuphar lutea (L.) Smith, Nymphaea candida J. Presl., Potamogeton spp. for Lake Antonievskoe; Lemna minor L. and Hydrocharis morsus-ranae L. for Lake Vitalievskoye. The similarity of the macrophyte species composition between subrecent SPS and modern aquatic vegetation was analyzed. A high level of similarity was noted only for two lakes – Lake Antonievskoye with the qualitative Jaccard and Sorensen- Czekanowski indices at 0.60 and 0.75, respectively, and Lake Zimnyakovskoye with a high value of the quantitative Bray-Curtis index (0.76). However, almost all macrophyte species that dominated the overgrowth area during our study were present also in subrecent SPS, which suggests that top-core bottom samples quite adequately reflect modern aquatic vegetation. The results prove that studies of macrophyte pollen in the lake sediments hold promise for the study of modern lake ecosystems and for paleoreconstructions.

For the first time for saline lakes of the Crimean Peninsula, the results of a comprehensive study of lacustrine sediments using litho-, bio- and chronological methods were obtained. For the first time, radiocarbon dating of the Crimean lake sediments was performed. In lakes Saki and Dzharylgach, sediment sequences of closed highly mineralized reservoirs, which overlay marine deposits, were retrieved. The surface of marine sediments is dated to 5610–5340 cal BP for Lake Saki and 5590–5350 cal BP for Lake Dzharylgach. By this time, sand barriers began to form, which subsequently completely separated the lagoons from the sea and led to the formation of closed reservoirs. Full isolation of Lake Dzharylgach occurred about 4600 cal BP. The vegetation change at the first stage of the lakes’ existence was controlled by changes in the sea level, as well as by fluctuations of salinity, later changes being mainly influenced by changes in climate humidity. The first Cerealia-type pollen occurs in the Subboreal period. Human settlements in the area of Lake Dzharylgach represent the Eneolithic, Bronze Age, as well as the Greco-Roman and medieval periods. A notable demographic change is observed in the period from the early first millennium to the end of the 5th century BC. The majority of archaeological sites in the vicinity of Lake Saki belongs to the Greco-Roman period.

The macrophyte pollen is a valuable source of information about lake level changes. Continuing our previous studies on the use of the macrophytes pollen analysis in the paleolimnology we studied the Lake Vitalievskoye sediments sequence of on the Valaam Island (the northern part of Lake Ladoga). To confirm the results of pollen analysis we conducted lithological and diatom analyzes. The macrophytes distribution of the island lakes at the present time has been established with the help of geobotanical and pollen analyzes of the lacustrine surface sediments. As a result, a comprehensive study made it possible to establish the stages of the Lake Vitalievskoye development during the Late Holocene: The Lake Ladoga Bay stage with a slight overgrowth of aquatic vegetation; the lake isolation stage of the from Lake Ladoga, when macrophytes disappeared from the lake, and the lake independent development stage, when their maximum distribution occurred and later began to decline as a result of the human impact. According to our research of the Valaam Island lakes we have received new data about the modern distribution of macrophytes in the island lakes, their dynamics in the Late Holocene. We also conducted a methodological study establishing the macrophytes pollen role in studying the small island lakes history and the Lake Ladoga level.

This paper discusses the results of siliceous microfossils studies performed in a "staircase" of four isolation basins (33.7 m-2.9 m a.s.l.) on Big Solovetskiy Island (Solovki Archipelago, the White Sea). Diatoms were used as a primary group for paleoinferences, while chrysophyte cysts and sponge spicules also demonstrated high indicative potential. In all study lakes, the siliceous microfossils stratigraphy revealed three main stages of their evolution, i.e. large-basin, transitional and small-lake stages, each characterized by certain composition of the diatom assemblages and floristic diversity, relative abundances of chrysophyte cysts and sponge spicules, and siliceous microfossils concentrations. In the uppermost lake, glaciolacustrine environments unfavorable for aquatic biota existed during the large-basin stage. The proglacial lake stage terminated prior to ca. 10.4 cal ka BP, followed by a (semi)terrestrial episode before the transition to small-lake environments. In the other three lakes, marine environments were inferred at the earlier stage, characterized by the predominance of marine and brackish-marine diatoms, increased proportions of sponge spicules and low "cysts to diatoms" ratio. At the transitional marine-freshwater stage, mass growth of small fragilarioid diatoms and decreased abundances of spicules indicated unstable environments, while increased proportions of cysts pointed to progressive freshening of the basins. The duration of the marine-freshwater transition expectedly prolonged from ca. 200 yr in the upper basin (16.6 m a.s.l) to ca. 500 yr in the lowermost lake (2.9 m a.s.l.). The isolation from the sea took place between ca. 6.3 and 1.4 cal ka BP. At the small-lake stage, siliceous microfossils stratigraphies reflected local specifics of the basins and their catchments. We argue that besides traditionally used diatom data, relative and absolute abundances of siliceous microfossils also possess high indicative value for isolation basin studies. Our study demonstrated that marine waters on Big Solovetskiy Island never reached ca. 34 m a.s.l. during the Holocene, unlike the western coast of the Onega Bay where the Preboreal marine intrusion was recorded even at higher elevated localities. Different rates and amplitudes of shoreline displacement are thus suggested for the inner and outer parts of the Onega Bay. During the mid-Holocene Tapes transgression, before ca. 6.3 cal ka BP, the relative sea level on Big Solovetskiy Island exceeded 17 m a.s.l. The average estimated rates of the shoreline retreat during the second half of the Holocene gradually decreased from 0.28 cm year  1 to 0.2 cm year  1, indicating slowed isostatic uplift.

Northwestern Russia remains the only region in Northern Eurasia where no regional chironomid-based inference model for quantitative palaeoclimatic reconstructions has been developed. Using palaeolimnological methods, we investigated the subfossil chironomid remains in surface sediments from a data set of 98 lakes from nine subregions of the European part of Northern Russia. We identified 143 chironomid taxa in the investigated lakes. Multivariate statistical analyses of chironomid and environmental data demonstrated that the mean July air temperature (T July), distance from the tree line, water depth, pH, and altitude explain the most significant variance in chironomid distribution. T July appeared to be the most important environmental variable. We established a chironomid-based inference model for reconstructing T July from subfossil data. The resulting West Russian two-component WA-PLS model includes 96 lakes (two lakes were excluded as outliers), 143 chironomid taxa, r2 = 0.84 (r2 boot = 0.60), RMSEP boot = 1.34 °C, and can be recommended for application in palaeoclimatic studies in the East of Northern Eurasia.

For the first time for saline lakes of the Crimean Peninsula, the results of a comprehensive study of lacustrine sediments using litho-, bio- and chronological methods were obtained. For the first time, radiocarbon dating of the Crimean lake sediments was performed. In lakes Saki and Dzharylgach, sediment sequences of closed highly mineralized reservoirs, which overlay marine deposits, were retrieved. The surface of marine sediments is dated to 5610–5340 cal BP for Lake Saki and 5590–5350 cal BP for Lake Dzharylgach. By this time, sand barriers began to form, which subsequently completely separated the lagoons from the sea and led to the formation of closed reservoirs. Full isolation of Lake Dzharylgach occurred about 4600 cal BP. The vegetation change at the first stage of the lakes’ existence was controlled by changes in the sea level, as well as by fluctuations of salinity, later changes being mainly influenced by changes in climate humidity. The first Cerealia-type pollen occurs in the Subboreal period. Human settlements in the area of Lake Dzharylgach represent the Eneolithic, Bronze Age, as well as the Greco-Roman and medieval periods. A notable demographic change is observed in the period from the early first millennium to the end of the 5th century BC. The majority of archaeological sites in the vicinity of Lake Saki belongs to the Greco-Roman period.

The macrophyte pollen is a valuable source of information about lake level changes. Continuing our previous studies on the use of the macrophytes pollen analysis in the paleolimnology we studied the Lake Vitalievskoye sediments sequence of on the Valaam Island (the northern part of Lake Ladoga). To confirm the results of pollen analysis we conducted lithological and diatom analyzes. The macrophytes distribution of the island lakes at the present time has been established with the help of geobotanical and pollen analyzes of the lacustrine surface sediments. As a result, a comprehensive study made it possible to establish the stages of the Lake Vitalievskoye development during the Late Holocene: The Lake Ladoga Bay stage with a slight overgrowth of aquatic vegetation; the lake isolation stage of the from Lake Ladoga, when macrophytes disappeared from the lake, and the lake independent development stage, when their maximum distribution occurred and later began to decline as a result of the human impact. According to our research of the Valaam Island lakes we have received new data about the modern distribution of macrophytes in the island lakes, their dynamics in the Late Holocene. We also conducted a methodological study establishing the macrophytes pollen role in studying the small island lakes history and the Lake Ladoga level.