Scientific results:
We have created the first laboratory for the research of ice cores in Russia.
To extend the chronology of climate events, which had been obtained by researching earlier collected ice cores, from Mount Elbrus, in August 2021 we have performed a complex of works at the plateau-like region in the eastern part of the Katyn plateau in the feeding area of the Bezengi glacier at 4750 m east of Elbrus. The works included drilling a well and collecting ice cores, measuring the temperature in the well, the radio probing of the body of the glacier, a complex of meteorological measurements, collecting samples in the snow pit, we collected an ice core up to the 93 m bed. In 2022, we drilled the glacier in the crater of the Ushkovskiy volcano (Kamchatka).
More than 1000 analyses of snow and ice samples from the eastern peak of Elbrus and Bezengi have been performed using ion chromatography, as well as an analysis of microparticles using Coulter method. We also performed an isotope analysis and determination of the content of overall organic carbon. Our researchers have established a system for sample collection form ice cores in a cold laboratory, clean collection protocols is observed, the purity of the used ultra-clean water is controlled.
We have analyzed 96,35 meters of ice cores from the eastern peak of Elbrus drilled in August2020. To conduct a chemically clean analysis, we cut a longitudinal section from every 57–60-cm of the ice core (resulting in a total of 163 ice cores) with a size of 34*34 mm and melted an inner 26*26 mm part at a rate of 35–40 mm/min. Using sealed pipes, we distributed the samples into fractions and simultaneously pumped them into the chambers of the analyzers. For the ice core of the eastern peak of Elbrus, we also analyzed microelements (Li, La, Ca, Ti, Pr, V, Cr, Mn, Ni, Sr, Fe, Pb, Be, Rb, Y, Al, Co, Bi, Cu, Mo, Ag, Сs, Cd, Zn) across the whol depth.
Data has been collected on the chemical and isotope composition of the ice core collected in 2021 on the Katyn plateau in the area of the Bezengi glacier and the ice core from the eastern peak of Elbrus. An analysis of the results indicates a low snow accumulation (0,3 -0,4 meters of water equivalent) and a significant age of near-bottom layers, which allows to suggest the maximum age of ice for the Caucasus mountains (over 2-5 thousand years). Samples were collected for absolute dating.
In oscillations of chemical elements and compounds in ice cores it is possible to observe a clearly expressed seasonal signal over the period from around 1774 to 2009. After the first research of the changes in mineral dust and contamination with sulfates we started studying other aspects of recent changes in the chemical composition of the atmosphere. Firstly, within the project we are studying changes in the concentration of two main nitrogen pollutants (ammonium and nitrates) and their relation to the increasing ammonium emissions from the agriculture sector) and nitrogen oxides (from transport). A comparison of the concentrations of compounds in the ice core with catalogs of emissions in the past was performed using the FLEXPART model of aerosol transfer in the atmosphere. Such an approach allows to increase the accuracy of carbon dioxide emission estimates, which is the key to the understanding of changes in ozone over Europe in the past and in the future. Knowing the prehistorical level of ammonium and nitrates in ice cores from Elbrus also allows to reconstruct ammonium and nitrates emission in southeastern Europe.
In comparison with inorganic aerosols (dust, sulfate, ammonium and nitrate), the research of the past changes in the organic fraction of the atmospheric aerosol from ice core data is not so widespread. Alpine ice cores recently indicated that the organic fraction of the aerosol provides an important contribution of aerosol that increased by the factor of 2-3 from the beginning to the end of the 20th century. On the basis of an analysis of 14C organic carbon (OC) present in ice it has been demonstrated that this increase in OC is mainly caused by an increase of emissions of volatile organic compounds (isoprene and monoterpenes) by plants, even though the parameters of the environment that caused this increase (earth, temperature, atmospheric СО2
levels) are poorly studied. This research is conducted in ice cores on Elbrus as well. The OC trend observed in the Elbrus glaciers from the beginning of the 20th century is weaker than in the Alps. Among other factors, one of the possible causes of such difference between Western and Southeastern Europe can be the less pronounced effect of agricultural activities on the use of forests in the Caucasus region compared to Western Europe.
The Laboratory has conducted an isotope analysis of wood samples from the European part of Russia. Data of measurements of the content of the stable carbon isotope δC13 has been collected. The data will be used for conducting a correlation analysis with meterological parameters, which will help to determine the climate signal recorded in the changes in δC13 in wood cellulose in pine wood from Yaroslavl and neighboring areas.
Our researchers have compared model data with the results of dendroclimatic reconstructions of summer temperature based on the optical density of annual growth rings of trees for Solovetsky Islands and North Caucasus (the 1500-1850 period was reviewed). The results of the modeling demonstrate a significant response of global yearly average temperature to the eruptions of the following years: 1600 (~0.7-0.9°С), 1640 (~0.6°С), 1695 (~0.5°С), 1783 (~0-1°С), 1809 (~0.4-0.9°С), 1815 (~0.5-1.7°С).
We have conducted a research of the dynamics of paleofires in the western part of Caucasus (Caucasian State Biosphere Reserve) from data of a paleoanthracological analysis of sediments of Lake Khuko (1744 a. m. s. l.) allowing to review the history of wildfires over the last 10500 years. The obtained data indicated a generally low wildfire activity in the Western Caucasus during the Holocene. An increase in the frequency of wildfires and the accumulation of coal nanoparticles was found over the last 500 years. An exception is the time interval between 4000 and 5200 years ago. Over this period the concentration of coal particles exceeds the background concentrations determined for the remaining part of the ice core by two orders of magnitude. We have found a series of wildfire events obviously corresponding to major and catastrophic wildfires on the adjacent territory. The age of these peaks matches the event that happened 4200 years ago that was characterized by the instability of climate conditions in the Northern hemisphere.
Within the problem of reconstructing the history of eruptions of Elbrus we have conducted a study of an ice core from Kubus Swamp (Republic of North Ossetia, N 42.89368, E 43.57733). We determined the concentration of cryptotephra on the basis of a study of micropreparations of 25-80 μm rhyolitic fraction from the lower part of the ice core that contained lake sediments. There is a high «background» content of cryptotephra in lake sediments, but it is also possible to find peaks of very high concentrations of cryptotephra apparently corresponding to volcano eruptions.
To obtain data on the composition of products of the latest eruptions of Elbrus, we have conducted an assay of visible horizons of Holocene tephra from sections on the southern and northeastern slopes of the volcano, including from lake sediments on the surface of a lava flow 1 km to the north of the village of Azau (N 43.275185б° E 42.480811°) and from a peatland in the lake basin int the Jily-Su area (N 43.44416° E 42.55577°). In the central part of the Jily-Su peatland we drilled the Jsu-2 well, collected a 4,2 meter-long ice core. Cumulatively we collected twelve tephra samples and samples of sediments for radiocarbon dating. Additionally we conducted work in the laboratory to study sediments from Lake Garabashi collected earlier.
In the course of expiditions we have collected samples of lava flows of different ages the Elbrus region for 36Cl dating. Since moraines of Elbrus glaciers are rich in pyroclastic material, to correctly determine their age from cosmogenic isotopes it is necessary to have a notion of the age of volcanic sediments. Currently data on Holocene eruptions of Elbrus are very scarce and are in fact limited to several radiocarbon datings of landscape forms adjacent to lava flows. We have collected 10 samples for 36Сl from volcanic sediments that supposedly come from the Holocene in the valleys of the Bolshoy Azau and Garabashi glacier. It has been determined that over the last 1600-1700 years none of the possible advance of the Irik glacier did not exceed 2.5 km in length. A similar in scale but slightly smaller advance occurred in the end of a minor ice age in the 1880s. One of the most significant advances of the Shkhelda glacier, according to cosmogenic dating data, belong to the period of 0.16 ± 0.03 ka 10Be, i. e. Happened in the 1840s. A moraine of this age was dated on the Kashkatash as well, according to denrochronological data; the advance of the Bolshoy Azau glacier in 1849 was described by the academician Abich upon his first visit to the glacier. Therefore, the first results of beryllium-10 dating of Caucasian moraines are in good agreement with the earlier found estimates but give new information, which is hard, and more often impossible, to obtain using other methods that have a limited time range of application.
We have created the first chronology of cell parameters of annual growth rings of trees for the European territory of Russia. The following key parameters were measured: the thickness of the cell walls, lumen area, average cell area, the minimum, average and maximum number of cells for each annual growth ring etc.
Our researchers have collected oak samples in the Caucasus to build a new oak chronology of humidity signal. In the North Caucasus we established three testing grounds of English oak (Quercus robur). Three tree-ring chronologies have been built according to the width of annual growth rings for living trees aged 100 and more. These chronologies increase the geographic coverage of the European part of Russia with dendrochronological data suitable for use in dendroclimatology. The measurements of the width of annual growth rings of archaeological samples were used to populate tree-ring chronologies of corresponding regions and extrapolating them into the past. According to statistics based on these materials, for every 10 measured archaeological samples it is only possible to include 30-50 per cent in the chronology. All the accumulated measurements of optical density from the Vologda, Kostroma and Yaroslavl regions were included into the existing chronologies to populate them for various periods (15th-20th centuries). This allowed to increase the reliability of the chronologies and obtain higher values of statistical characteristics for building climate reconstructions on their basis.
At the key testing site for the study of soil archives of paleofires on the Teskie Keivy of the Kola peninsula the most recent of the buried pyrogenic horizons had an age of 130±75 cal BP, while the oldest horizons encompassed a period of 10635±45 – 9595±45 cal BP. The earliest date was obtained for charred remains of root systems in early-Holocene soil that can be traced in all three trenches. The age of other carbonaceous particles lies within the 6560±45 – 305±60 cal BP range of dates. While distributing radiocarbon datings along the depth we did not detect any inversions, which additionally confirmed the high quality of data writing in the archive with a sedimentary «book-like» type. The majority of the pyrogenic horizons was comprised by charred matter with a 69,60±4,85% content of C, 0,42±0,29% of total nitrogen, 265±143 of C/N and a very minor variation in the ratio of stable carbon isotopes (δ13С) – -25,69±0,92‰ (the majority of carbonaceous particles belongs to coniferous trees).
The array of radiocarbon datings for carbonaceous particles from pyrogenic soils of the Teskie Keivy of the Kola peninsula reached 75 measurement, which allowed to build a distribution of the total density of possibility within the intervals of calibratedrediocarbon age for buried carbonaceous particles. We isolated several periods of increased pyrogenic activity: 10600-10200, 9800-9400, 7600-7200 and 6800-5200 cal BP as well as fluctuations around the relatively constant high level since 4500 cal BP to date. The fireless periods were most pronounced 9400-8800 and 8200-7600 cal BP. The maximum number of fires over a millennium according to the distribution of mean values reached 15 and belongs to the 6000-5000 cal BP period.
Therefore for the Teskie Keivy of the Kola peninsula in the same manner as the glacier-carst landscapes of Kuloy and Pinega in the north of the Arkhangelsk region, we detected wildfire activity starting from the early Holocene 10600-10200 cal. BP. In these regions in the early Holocene there already was a sufficient amount of plant biomass for intense combustion and the production of large yields of carbonaceous particles belonging, among others, to wood species. During this period vegetation with extensive root systems could establish itself, which was found in all the researched trenches on the Teskie Keivy.
Education and career development:
With the direct participation of employees of the Laboratory, teaching disciplines at the Faculty of Geography and Geoinformation Technologies of HSE University have been created and launched. The teaching discipline «Earth spheres» within the section devoted to the cryosphere incorporates a number of theoretical and practical classes conducted at the Laboratory itself. The teaching discipline «Environmental changes in the past and paleogeography methods» is effectively conducted at our Laboratory with the participation of the majority of research groups.
A number of methodological approaches, as well as examples and data for work at seminars for the discipline «Mathematical methods, analysis and data visualization in the study of natural systems», has been produced within the project.
Collaborations:
- British Antarctic Survey (United Kingdom), Laboratory of Environmental Geophysics of Université Grenoble Alpes (France), Paul Scherrer Institute (Switzerland), Ohio University, Center for Applied Isotope Studies (CAIS) of the University of Georgia (USA): joint research.
- Arctic and Antarctic Research Institute, Institute of Geology of Ore Deposits, Petrography, Mineralogy and Biochemistry of the Russian Academy of Sciences, A. M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences, Moscow State University (Russia): joint research and publications.
