No 4 (2022)

Lake Ladoga has been experiencing frequent water-level fluctuations during the Holocene. Plenty surveys about reconstructions of lake level were published during the last century. They focused on the onshore transgressive sediments and landforms, while a regression below present level was only an assumption. Here for the first time, we present indications of lake-level lowstands by means of sediment echosounder data collected within the “PLOT-project”. Three types of landforms of coastal and terrestrial origin are detected in the basin. These are coastal bars, erosional terraces and buried erosional valleys. Three paleo-shorelines were determined at depths of 13, 21 and 40-42 m. The first two shorelines are identified by the presence of the coastal bars, while the level of maximum regression is obtained from erosional marks. Reported landforms are assumed to be formed in the Early Holocene following the Baltic Ice Lake drainage.

In this study we aimed to find a Tver proglacial lake in the Upper Volga low land at the Late Valdai that it have been reconstructed by D.D. Kvasov. Our field studies did not verify previously reconstructed lake terraces at 135 – 140 and 120 – 125 m a.s.l., though at 140 m a.s.l. we found the Volga River terrace near Seslavie (Tver region, Russia). According to OSL data from this terrace, the Volga River has existed in the Upper Volga lowland ever since the LGM.

The data on studies of sedimentation processes in the Lake Onego were collected. The research program includes monitoring of atmospheric precipitation, the river flow, the distribution of suspended matter in the water column, the flow of suspended matter to the bottom and point source of pollution. The distribution and accumulation rates of sedimentary matter in the lake were determined. The composition of sedimentary matter has been studied.

The study represents correlation δ¹⁸O records from the Caspian basin together with available stable oxygen data on the continual sequence of deep-sea cores and on Kara-Bogaz-Gol Gulf, nearby lakes, and caves to complete palaeogeographical reconstruction of the Caspian Sea region. Typical Quaternary caspian ostracods shells and valves were measured for the δ¹⁸O analysis. Oxygen isotope data allowed to correlate region transgressive-regressive events with glacial-interglacial rhythm and global climate changes. It was distinguished three main evolution stages of the Caspian Sea region, including the Last Ice Sheet degradation with a series of step-like environmental shifts matching the sequence of abrupt cooling/warming events; abrupt warming at the beginning of the Holocene; and climatic fluctuations of a smaller scale and different sets during the second part of the Holocene. It was established that Caspian Sea level oscillations occur as a response to climatic changes among numerous probable causes. Transgressions were usually accompanied by the freshening of water and cold climate while regressions were primarily correspond to increased salinities and warm climate. The reconstruction of the Caspian Sea hydro-climatic changes was confirmed by observed similar trends in the oxygen isotope record of nearby regions.

The core-top calibration study of 22 lakes indicates that in salt lakes the total alkenones increase sharply at a salinity of about 20 g/L, while alkenones are absent in the sediments of freshwater lakes. For the first time, this study shows that the Uk40 and Uk40’ unsaturation indices are positively correlated with salinity and thus can be used to reconstruct salinity. The C37/C38 ratio is negatively correlated with salinity, and therefore this parameter can be used as an indicator of salinity. Also, the %C37:4 indicator is not correlated with salinity. It was found that the average chain length of alkenones increases with salinity, but the correlation was weak. Analysis of the alkenone composition and 18S rRNA suggests that all lakes are inhabited by Group II haptophytes, except for one freshwater lake, where the Group I of LCA-producing haptophytes was found. The taxonomic composition of haptophyte algae and the alkenone composition in the lakes were comparable to those in the lakes of the Canadian Prairies, apparently due to the similarity of climatic factors and the ionic composition of lake water in the two regions.

High-resolution seismic data (65 km profiles) have been used to study the sedimentary infill of Ivan-Arakhley lake system (Lakes Arakhley, Ivan and Shakshinskoe). It found that full limnological cycle bears only sediment cover of Lake Arakhley. Total sediment infill of Lake Arakhley is 6-7 m, and it was be divided into three sequences. The uppermost ~2.5 m of sediment cover was presented by a normal lacustrine filling. Lacustrine sediments began to form ca. 21 cal. ka BP. The lake was almost dried during the regression occurred between ca. 3 and 2.6 cal. ka BP.

The study of lake sediments contributes to the understanding of the types and intensity of anthropogenic impact on the landscapes of the Vishtynets Upland (Southeastern Baltic) in prehistoric times and the Middle Ages by combining available paleoecological and archaeological information. The results of lithological, paleobotanical and geochemical studies, together with archaeological data, have allowed a deeper understanding of the dynamics of anthropogenic impact in the area, including the emergence of agriculture and ancient metallurgy. Archaeological data testify to the presence of human activity on the Vishtynets Upland from the Late Paleolithic, and applied paleolimnological analysis revealed the first signs of anthropogenic impact, starting from the Late Mesolithic and Neolithic, and intensifying it from the Bronze Age.

The article discusses the first results of geomorphological and paleolimnological study of Lake Chukhlomskoe (Kostroma region). We analyzed the topography of the lake bottom using new bathymetric data from 2021 fieldwork. The structure of the lake basin slopes was studied using hand drilling. Analytical characteristics of the bottom sediments core (grain size distribution, loss on ignition, magnetic susceptibility, AMS-dating and palynological data) are presented. The distribution of organic matter, carbonates and particle size by depth allow us to correlate the bottom sediments of Lake Chukhlomskoe with the sediments of other well-studied large lakes (Belaya Struga, Galichskoe and Seliger).

Aquatic vegetation is a sensitive indicator of lake structural rearrangements, water level changes, overgrowth and waterlogging processes. Although macrophyte pollen may not be well preserved in lake sediments, it is a valuable source of information about an evolution of lakes. Continuing our previous researches on the use of macrophyte pollen analysis in paleolimnological studies, we have explored the sediments sequence of Lake Vitalievskoye on the Valaam Island (northern part of Lake Ladoga), that was isolated at the Ladoga regression for the Late Holocene. We have used pollen analysis of the sediments sequence with focus on the dynamics of aquatic vegetation. Based on our results, the macrophyte dynamics at every stage of the Lake Vitalievskoye development and relationship with the Lake Ladoga level changes in the Late Holocene were reconstructed.

The work combines physicochemical and statistical modeling in the description of marine and continental salt water bodies. Sedimentary systems consist of aluminosilicate, carbonate and organogenic source material. Paleoclimatic changes are traditionally considered in the time scale. However, the real fluctuation amplitude of the target natural parameter is usually absent or has insufficient resolution for quantitative paleoclimatic reconstructions. Accessible quantitative analysis of time series is based on mineralogy and geochemistry of bottom sediments. Ahalytical complex includes X-ray phase diagnostics of minerals, SEM and XRF analysis of bulk chemical composition, isotopic dating and counting of annual rhythms. Modern high-resolution techiquem like scanning XRF SR with a measurement step of 1 mm successfully provides the necessary synchronization between analytical data and instrumental seasonal-annual observations. Multiple regression methods are used to calculate the transfer functions for transforming the elemental composition of sediments into time series of the desired target environment. Additional physicochemical equilibrium estimates of sedimentation were calculated, confirming the convergence of the parameters of the selected multisystem (rock + liquid + gas) with environmental conditions. For equilibrium systems, time series of absolute values of the desired parameters, such as temperature, salinity, pH, redox environment, etc., were calibrated with synchronous weather and climate fluctuations. In particular, the reconstruction of marine sediments opened up the prospect of studying the periodicity of ice-free periods in the Arctic Ocean, using quantitative estimates of external conditions from the lithochemistry of bottom sediments.

The ostracod record from Lake Sargul infers details of two-stage development of the lake ecosystem during the Holocene.

According to the study of bottom sediments, the Belye Lakes (near the famous mound Arzhaan-2) begun to exist about 16.5 ka. The lakes formed in a local depression at the site of the alluvial fans of temporary rivers, which is marked by red sands in cores. A three-meter lacustrine stratum overlies the sands, in some places with interbeds of peat, with a variable content of organic matter and carbonates along the section. Lithological, diatom and pollen analyzes show that the lake has always been shallow. The minimum flowability of the lake, indicating drier conditions, existed 10.0-4.2 ka and for the last 2.0 ka. During the middle of the Holocene (between 8.3-4.2 ka) it could dry up temporarily.

The paper presents geomorphological evidences of former appearances of huge lakes in Mongolia and in the south of Siberia visible on satellite images. Most of lakes in Mongolia and transboundary Russia are terminal basins collecting waters from catchments of large rivers draining the Altai, Khangai and Khentey Mountains, while in the south of Siberia such lakes had no sizeable sources for water input. The discussing reasons for these rises are obviously climatic with possible high influence of deglaciation processes in the surrounding mountains.

Suspended matter entering Lake Onego with river runoff was studied from 2019 to 2021. Observations on rivers in different seasons on the basis of an interdisciplinary systematic approach combining modern landscape-geographical, biogeochemical, mineralogical, geochemical, hydro-chemical, ecological methods allowed us to gain new knowledge about the weighted average flow of substances into Lake Onego for seasonal variability.

This article discusses the interaction of ancient man and the aquatic environment in the Western Manych River Valley.

The results of modern processes observations of the sedimentation in the volcanic lakes of the region are summarized with the use of material from other regions of the world. The available data on the drained volcanic lakes deposits, Uzon-Geysernaya caldera as example, was analysed. The main sources of material (volcanic and post-volcanic activity, gravitational displacements on slopes, and erosion-denudation processes) and the mechanisms of its entry into volcanic lakes, as well as the features of the subsequent deposits transformation as a result of hydrothermal, seismic, and volcano-tectonic activity, are identified. The results of the studies carried out allow us to conclude that the volcanic lakes deposits are complexly constructed polyfacial complexes with alternating fine-grained lacustrine and lacustrine-swamp deposits with pyroclastic horizons and interlayers of untreated or poorly processed coarse clastic material coming as a result of volcano-tectonic activity, gravitational and erosion processes. The irregularity of horizons along strike is typical; and is characterized by the large-scale sediments deformation under the influence of seismic activity, growth of effusive and extrusive domes, phreatic explosions, etc. Hydrothermal activity contributes to the weathering and cementation of the lake sediments. Lava outpourings and the high-temperature pyroclastic flows provokes sintering of contacting horizons sediments.

Diatom analysis is one of the methods of paleolimnological research, with the help of which it is possible to determine the state and development of aquatic ecosystems in the past and present. Assessment of the current state of reservoirs is of great importance in paleolimnology, it will allow to obtain results about temperature regime, mineralization, pH environment and water quality. The research area is a region with a lot of small polygonal reservoirs that react quickly enough to external environmental changes that are formed during the cracking of re-vein ice and may form large reservoirs in the future. In this work, the IP-1 monitoring reservoir of the Kytalyk locality was studied for 10 days (every three days) during the expedition work carried out in 2011 using standard methods and a set of field equipment. The material of the study was phytoplankton samples, as a result of which the taxonomic composition of the diatom flora was investigated and the water quality of the Kytalyk monitoring site located in the basin of the Berelyakh river, the left tributary of the Indigirka, was determined.

The study of the siliceous microalgae (diatoms and chrysophytes) enabled reconstructing the evolution of the ecosystem of the Unitskaya Bay, the northern bay of Lake Onega. Changes in the composition of diatom assemblages, floristic diversity and abundances of siliceous microalgae indicated past productivity changes, as well as shifts in duration of hydrological and biological seasons.

Comprehensive studies of chemical and mineral composition of two lake systems on the territory of the Baraba lowland in the south of western Siberia was carried out. The reserves of sapropel and carbon were calculated for each lake. Sources supply of material and forms of carbon burial in the bottom sediments were identified.

We present the results of study the Holocene sediments of Itkul Lake, a shal low brackish lake with carbonate sedimentation, located in the eastern part of Baraba lowland (Southwestern Siberia, Novosibirsk Region). A 1.8 m thick core of the Holocene (7.9 ¹⁴C yr) sediments of Itkul Lake has been studied. Based on the geochemical and lithostratigraphic properties of the bottom sediments, we have established the following stages of the lake evolution: (I) the beginning of sedimentation, 7.8–7.0 ¹⁴С ka; (II) extreme shallowing with a probable complete drying, ~7.0–5.5 ¹⁴С ka; (III) rise in the water level, ~ 5.5–4.3 ¹⁴С ka; (IV) repeated shallowing, 4.3–2.8 ¹⁴С ka; and (V) subsequent watering, 2.8–0 ¹⁴С ka. At present, the lake again tends to shallowing.

Ice gouging landforms on the exposed bottom of the Aral Sea give a possibility to get a profound knowledge about processes of the ice-bottom interaction during the level fall. We analyzed ice scours in the different parts of the Aral Sea using geomorphological and remote methods and evaluated the paleoreconstruction of ice gouging processes in the Anthropocene.

The Perm Kama region is characterized by numerous promising paleoar chives, and the paleoecological knowledge of the region is uneven. Identification of the dynamics of organic carbon accumulation in peat is included in the complex of studies used to reconstruct the state of the natural environment in the past. We have studied peat deposits of the Verkh-Invenskoe bog in the western part of the region. For this, depth measurements, sampling of a peat column, and laboratory analysis of samples throughout the thickness were performed. As a result, indicators were determined: Bulk Density (further – BD), Organic Matter Bulk Density (further − OMBD), Loss on Ignition (further – LOI), Long term average rate of carbon accumulation (LORCA). For the first time for the western part of the Perm Kama region, numerical data on the dynamics of carbon accumulation over the last 10.9 thousand years have been obtained.

Here we present the pollen spectra of the Central Kamchatka depression from 28.4 to 7.9 ka. Our study is based on a key lacustrine section Kamplen that deposited in a Late Pleistocene mega-lake and thus represents an integral peninsula-scale record. Pollen analysis allows us to identify seven local pollen zones reflecting the main stages of vegetation and climate change.

Based on the palynological analysis of the bottom sediment column of the arctic lake with the code name 21-Ya-01A of the Erkuta River basin from the southeastern part of the Yamal Peninsula, we received preliminary information on climatic changes, as well as on changes in vegetation character in the area around the water body. According to the results of the palynological analysis, the area around lake 21-Ya-01A was occupied during the Holocene by tree species (dwarf birch, spruce, larch) and characterized by a much warmer climate than today. It has been determined that the lower part of the column from 122 cm to 95 cm formed when dwarf vegetation and light birch-spruce forests covered the territory at that time. The middle part of the column from 95 cm to 15 cm laid under more favorable conditions - the climate was warmer and wetter than in the previous phase. It can be assumed from the spectra from 15 cm to 0 cm of the column that the climate was characterized by even colder temperatures and that the territory turned into a dwarf shrub–yernik tundra.

In this present article, we describe disturbances in the sedimentary records of lakes on the western flank of Lake Imandra (NE Fennoscandia, Kola Peninsula). The research framework comprises sedimentological and textural criteria for a visual description of sedimentary structures, borehole drilling data, chronological (radiocarbon dating) data, and ground-penetrating radar (GPR) data. Synchronicity specific features and fast spontaneous sediment accumulation in lakes, as well as traces of strong prehistoric and historical earthquakes and geomorphic setting in the studied area suggest that the observed mass movements in lake sediments are potentially generated by earthquake shaking.

Results of radiocarbon dating and spore-pollen analysis of lacustrine sedi ments in the Nyrki sectionfrom the Yurumkuveem river basin (Central Chukotka) show the wider distribution of floodplain forests and the warmer climate in this time in the region in the early Holocene than in the present time. The occurrence of larch (Larix) in the vicinity of Nyrki lake in the early Holocene is also discussed. Our data suggest that the larch range was expanded to the Yurumkuveem river valley and its inflows during the early Holocene, but this tree disappeared from there in the late Holocene.

Grain size and chironomid analyses of the upper core of the Usvyatskoye Lake (Pskov area) were carried out. The estimated age of the core covers the last 2000 years. Preliminary results of grain-size analysis identified four facies in the studied core. Analysis of chironomid taxonomic composition showed a change in dominant taxa, that is correlated with changes in grain size.

In this work we present the results of reconstruction of the dynamics of paleo-fires over the last 3300 cal. yr BP in the Barabinsk forest-steppe of the Western Siberia based on macrocharcoal analysis and radiocarbon dating of peat deposits of the Nikolaevsky ryam. The authors identified 18 local fire episodes using the CharAnalysis program. At the end of the Subboreal period, 6 local fires occurred, probably caused by dry and cold conditions. In the subAtlantic period of the Holocene, 12 fires were recorded with a peak of pyrogenic activity at 1200-1000 cal. yr BP. This peak of fires is probably associated with the warm and dry conditions of the Medieval Climate Optimum. As a result of the study, it was concluded that the intensity and frequency of paleo-fires in the area of Nikolaevsky ryam were influenced by climatic changes: in dry climatic periods, an increase in fire activity was observed.

Holocene aeolian topography and sediments were investigated at two key sites on the Zimny Coast and one key site on the Kaninsky Coast of the White Sea. Field work included ground penetration radar profiling, paleolimnological and geomorphological study, as well as aerial imagery and topography surveys. Analytical studies including grain-size, geochemical and diatom analyses and radiocarbon dating of lake sediment cores were performed. Accumulative aeolian relief was formed in areas with a positive coastal-marine sediment balance. The sands are brought in by a longshore drift or river discharge. The aeolian topography and the number of stages of aeolian activation vary across the key areas. The present-time coastal dunes have been forming since the late or middle Holocene, when relative sea level became close to contemporary levels.

Detailed studies of processes of sediment record formation are necessary for accurate sediment-derived paleo-environmental reconstructions. We conducted the multi-year seasonal sediment evolution of sediment fluxes of chemical elements, organic and inorganic carbon, total nitrogen, and photosynthetic pigments for a period from 2012 to 2017. In 2013, 2016, 2017, and 2018, we estimated the contents of photosynthetic pigments in the uppermost sediment layers frozen in situ with a freeze-corer. In 2015 and 2016, a rare event of transition from meromixis (i.e. long-term hypolimnetic anoxia) to holomixis was observed, which was accompanied by the temporary disappearance of hydrogen sulfide from the water column in spring and a decrease in hydrogen sulfide in other seasons compared to the meromictic state. We have demonstrated that okenone and Mo in the Lake Shira sediments reflect the presence of hydrogen sulfide in the water column. However, the okenone showed smoothened multi-year dynamics without a pronounced seasonal one. Therefore, the okenone can be a proxy of sulphidic conditions in photic zone and weakly depend on seasons whereas Mo can be used as an indicator of winter periods when analyzed in cores with annual resolution. Sedimentation fluxes of other substances showed typical seasonal dynamics with a minimum in winter and a maximum in late summer and autumn. All chemical elements in the sedimentation flow can be roughly divided into those associated with organic matter and terrigenous-chemogenous. The components of the second group showed a pronounced peak of sedimentation in autumn 2012 and summer 2017 presumably due to the increased amount of precipitation at that time. This demonstrates the relationship between the terrigenous components and the climate humidity for this lake. Besides, it reflects the irregularity of annual varves composition.

A comprehensive lithological analysis of bottom sediments from the central part of the Sarskaya depression was carried out. We determined that a shallow lake existed in the Sarskaya depression as least from 22500 to 12400 years ago. The bottom sediments potentially contain traces of global climate change - in particular, a presumable trace of the Bølling-Allerød interstadial has been established in sediments formed about 13500 years ago. There are signs of activation of erosion processes during the period from 13100 to 12400 years ago. Since the time the sediment condition stabilized and the water body began to swamp.

The issues of the formation of the largest lakes in Europe - Ladoga and Onega are considered in the article. The main aim was to identify features of the basins development from their origin to modern condition. The newest geological and geophysical data obtained in 2014-2021 was used to achieve the goal. Both depressions, in which modern lake basins are located, were formed in the Late Proterozoic. In the Late Quaternary, the glacier significantly modeled the pre-Quaternary relief. Glacial tongues significantly expanded the negative forms of the pre-glacial relief. At the same time, the glacier also formed positive landforms, such as moraines and esker ridges. Such ridges intersect the Lake Ladoga center and mark the position of the Neva stage. Structural features of the supraglacial section are considered in detail. It is shown that in both lakes the structure of the upglacial section is approximately the same and is associated with the gradual retreat of the glacier from the lake basins. Thus, it is shown that, despite the similarity of the main stages of paleogeographic development, each lake basin was characterized by its own features and their development itself occurred asynchronously.

Our reconstructions of vegetation changes are based on the results of pollen analysis that was carried out for the sedimentary sequence located on the lacustrine-alluvial terrace west of Lake Nero. To clarify our conclusions, six ¹⁴C dates were obtained and an age-depth model based on these dates was constructed. It is established that open spruce-birch forests were widespread during the Allerød and Younger Dryas. Since the Preboreal stage of the Holocene, a peat bog began to form surrounded by pine and birch forests with spruce. The Boreal stage was marked by an increased role of broad-leaved trees in the forests. During the Atlantic period, climatic conditions became warmer and spruce-pine forests with thermophilous deciduous trees started to grow. The vegetation cover of the Late Holocene (SB-SA periods) was dominated by spruce forests with pine and birch.

The first geochronological data have been obtained for the lacustrine deposits of the Manych Depression, discovered by a borehole. It was found that two horizons (burtass and gudilovsky) of sedimentation were distinguished in the lacustrine deposits separated by an erosion gap. The age of the Burtass Lake deposits is estimated at 78-100 ka years ago (MIS 5), Gudilovsky Lake — 25-64 ka years ago (MIS 3).

The study examines the issues of changes in the level of the Baltic Sea over the past 10 thousand years. According to the data of domestic and foreign authors on time, there is no unambiguous data on the duration and level of littorina transgression, which is considered the largest during the Holocene period. By the research, with the financial support of the RFBR grant-graduate students No. 20-35-90089, studies of bottom sediments of lakes Goluboye, Bolshoye Molochnoye and Zaychikhinskoye are being carried out. The report presents the results of the diatom analysis of Lake Zaychikhinskoye. The main stages of the lake’s development are determined, it is established that in the early Holocene its development was determined by the transgressive-regressive stages of the Baltic. At the initial stage, the reservoir was part of a deep oligotrophic Ancylus lake. During the littorina transgression, the Baltic Sea level most likely did not rise to lake level in this area.

The research of Barents Sea coastline dynamics is based on isolated basins method: bottom sediments were sampled in the chain of lakes located in the area of Musta-Tunturi ridge by the Barents Sea coastline and on the isthmus between Sredniy Peninsula and mainland part of the region, the expedition took place in July 2021. This report presents common results of grain-size and LOI (losses on ignition) analyses of 4 lakes’ bottom sediments. Deepest uncovered sediments are associated with marine genesis and characterized by the biggest average particle diameter and the lowest percentage of organic matter. Layers previously supposed as transgression sediments also have dissimilar grain-size structure from other layers of the core and low percentage of organic matter.

We present the results of the study of the Holocene sediments from two shal low lakes of different salinity located in the East Baraba lowland (Southwestern Siberia). The research methods: X-ray diffractometry (XRD), IR spectroscopy, laser particle size analysis, AMS dating, etc. By the mathematical modeling of complex XRD patterns Mg-calcites with different Mg contents, excess-Ca dolomite and aragonite have been established in the assemblages of carbonate minerals. Based on studies of mineralogical-crystallochemical features and quantitative ratios of Ca-Mg carbonates the evolution stages of lakes corresponding to the regional cycles of aridization/humidization were identified and the correlations with global climatic events were carried out. The obtained results are an important source of new information about the Holocene climate in the Southwestern Siberia.

Comprehensive studies (lithological and micropaleontological) of bottom sedi ments from nine lakes at the Teriberka Village (the Kola Peninsula, Northwestern Russia) were carried out. The sediments formed after an isolation from the sea was dated. Based on these new data, a preliminary sea-level curve for the study area was constructed. The sea-level curve indicates several phases evolution of the Kola coast during the Late Glacial and Holocene. Rapid drop (~ 40 mm per year) of a sea-level was occurred ca. 11,500 cal. years BP. The sea level gradually elevated between ca. 11,000 and 7,600 cal. years BP (the Tapes transgression). Science ca. 7,300 cal years BP, the sea level slowly decreases by 2–3 mm per year.

The Ice battle is one of the most famous battles in Russian history. However, there is still no clearly answer as to where the Ice battle took place. Paleogeographic reconstructions can help in finding the place of the battle. The study area is a section of the southern part of Pskovsko-Chudskoe Lake. The works were carried out in the vicinity of Samolva and Kobylie Gorodishche villages of Gdov district of Pskov region, in the Zhelchensky Bay of Pskovsko-Chudskoe Lake. The key methods in this work are bathymetric survey, bottom sediment sampling, and lithological analysis. Three main types of bottom sediments are distinguished: sands at the bottom part of core section, upper it overlain by a thick layer of peat, which covered by gyttja.

This paper provides information about diatom assemblages in sediments of large arctic reservoir (Lake Imandra). The distribution of the taxonomic composition and structure of diatoms for several centuries has been studied. The periods and causes of changes in the state of the lake ecosystem are determined, and a conclusion about future trends is made. The data obtained can be used for monitoring the ecological state of the environment and water bodies.

Generation of biodiversity during the Neopleistocene and the Holocene was determined by the parameters of aquatic environment of basins (the sea-level mode, temperature, salinity), mainly reflecting climatic changes. The anthropogenic factor contributes essentially to the structure of the biodiversity. This paper aimed to show the impact of natural and anthropogenic factors on the generation of the mollusk’s biodiversity. The material for research was the analysis of the long-term field works of the author on the coasts of the Caspian Sea and the studying of the core of sea boreholes. It is cocluded that over the last 6 thousand years, invasive and acclimatized species made much more significant changes in biodiversity than those caused by natural factors. Natural ecosystems have undergone the anthropogenic transformation. Over the course of historical time, there has been not only fast change in biodiversity, but also irreversible change in aquatic ecosystems. The role of the anthropogenic factor on the species distribution in the basin became the major.

The reconstruction of vegetation changes of foothill zone in the central part of the North Caucasus based on the data of the Tarskoe swamp is presented. The swamp is the largest in this region of the Caucasus and is the most promising peat paleo archive. It has been studied earlier, but the cores were poorly dated. The Tarskoe was re-drilled, the sediments were dated, and pollen and microcharcoal analysis were carried out. Twelve radiocarbon dates were obtained for the deposits, the age of the bottom sediments was about 4.6 cal. ka BP. Based on the data obtained, it was possible to establish that the of the bogging occurred against the background of more open landscapes, with a greater proportion of meadows than at present. Only after 4.4 cal ka BP broad-leaved forests become more closed, in their composition Fagus were dominant, with alternating admixture of Carpinus, Ulmus and Alnus. The increase of Alnus after Cyperaceae is most likely reflect local changes, since this tree species settled in the swamp at a late stage of its development. The dynamics of fire activity is interesting, it is most pronounced in the intervals between 4.4-3.3 cal. ka BP and then from 2.2 cal. ka BP until present. The frequency of fires is probably related not to climate, but to anthropogenic activities. In almost all cases, this coincides with the appearance of cultivated cereals pollen and with an increase in the diversity and quantity of grasses associated with humans (weeds). Thus, the obtained data for the first time give a possibility to construct a dated sequence of changes in the composition of broad-leaved forests of the belt of Caucasus piedmont and confirmed the appearance of cultivated cereals pollen about 4.3 cal. ka BP, which is probably associated with agriculture of the Maikop culture.

We present the new results concerning the chronology, distribution and dynamic of the proglacial LGM lakes in the valleys of the Severnaya Dvina and its largest tributaries Vaga and Sukhona. Our results refute the hypotheses of the extensive distribution of proglacial lakes and their flow to the south during the LGM. The lakes were local, with an unstable hydrodynamic regime and extended to a distance of 100-170 km from the ice sheet boundary.

The analysis of the proxy archives from lake sediments made it possible to install the natural indicators the Holocene into three stages at 8200 and 4200 cal. yr. BP, the timing is consistent with that seen in the Greenland ice-core data. We studied proxy archives based on pollen-stratigraphic, sedimentological, radiocarbon and isotopic dates.