Multidisciplinary studies of the bottom sediments–water column–atmospheric water layer system in the Barents and Pechora seas and Baydaratskaya Bay of the Kara Sea were carried out on the expedition European Arctic–2023: Geological Record of Environmental and Climate Change during the season of polar night and active development of autumn–winter thermal convection. Fundamentally new data on a number of areas of oceanology were obtained in the cruise.

The results of describing the spatial distribution of methane concentration in the surface water of Lake Baikal in the spring are presented. The basis was the measurements of CH4 content which were first carried out in the round-the-clock continuous mode along the entire route of the passage of research vessel in the complex expeditions of Limnological Institute, Siberian Branch, Russian Academy of Sciences, in the spring seasons of 2013, 2016, 2017, 2018, 2021, and 2022. Based on the results of six expeditions, a merged data array was compiled; it included 12 100 segments (with a step of 0.005° in latitude and 0.01° in longitude) which covered the total area 4466.7 km2, or 14

The gross and net primary production is estimated for the most characteristic seasonal life cycles of Baikal plankton based on long-term measurement series of carbon dioxide concentrations in the near-water atmosphere and surface and bottom water and “water–air” carbon dioxide fluxes. The calculations are carried out according to the scheme similar to the diel technique. With regard to the conditions of the coastal zone, the methodological issues are analyzed, neglect of which can lead to a significant uncertainty in these characteristics. We show that it is impossible to correctly estimate the net primary production only from CO2 concentration measurements in this technique. For periods of open water, the net primary production is calculated from the daily average CO2 flux. The estimates of the productivity for individual series of measurements in different periods quite adequately show the main features and are consistent with long-term observations.

We discuss the methodical aspects and approaches used to arrange solar radiation measurements at the Fonovaya Observatory at the V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, and the capabilities of the new radiation unit, integrated into the Observatory measurement system in 2020. It is equipped with a set of instruments allowing a continuous monitoring of the total (0.285–2.8 μm), total UV (0.280–0.400 μm), and UV-B radiation (0.280–0.315 μm), as well as the radiation balance. We describe the capabilities of software specially developed for the measurement data acquisition, transmission, and processing.

Ground-based measurements at the Fonovaya Observatory in 2021 are used to analyze the variations in solar radiation in the wavelength ranges 0.285–2.8, 0.280–0.400, and 0.280–0.315 μm. The calculations of the radiation balance and albedo of the underlying surface are presented. The diurnal radiation balance is shown to be −1.20 ± 1.18 MJ/m 2 during the period of stable snow cover, from November to March, and +8.83 ± 4.49 MJ/m 2 in the snow-free period, from May to September. The diurnal solar radiation absorption by the Earth’s surface is estimated to not exceed 2 MJ/m 2 during the period of stable snow cover, from December to March, and to vary from 10 to 25 MJ/m 2 in summer.

В докладе дано описание и технические характеристики радиационного блока измерительного комплекса обсерватории «Фоновая». Приводятся результаты измерений солнечной радиации в диапазонах длин волн λ=0,285÷2,8 мкм, λ=0,280÷0,400 мкм, λ=0,280÷0,315 мкм и результаты расчета радиационного баланса и альбедо подстилающей поверхности за 2021 год.

Проанализированы многолетние ряды наблюдений потоков углекислого газа и метана в системе «вода-атмосфера» в прибрежной зоне озера Байкал. По результатам многолетних измерений показано, что суммарный сток углекислого газа из атмосферы на водную поверхность составляет 5,9 гСО2 м-2 год-1, а выход метана из воды оценивается в 100мгСН4 м-2 год-1. Для сравнительной оценки радиационного эффекта предположим, что молекула метана поглощает ИК излучение в 20 раз эффективней по сравнению с молекулой СО2. Показано, что суммарный сток углекислого газа из атмосферы в течение года достоверно снижает радиационный эффект, обусловленный выходом метана.

Начальные и граничные условия для распределения концентрации газовых составляющих были заданы с использованием результатов расчётов двух глобальных химико-транспортных моделей. Для 2011 года была использована модель MOZART4, а для 2021 — WACCM. В результате было показано, что для 2011 года модель достаточно точно восстанавливает среднесуточные значения концентрации угарного газа и озона. Концентрации оксидов азота и сернистого ангидрида показывают качественное согласие временного хода. Для 2021 года модель демонстрирует заниженные значения, как для угарного газа, так и сернистого ангидрида и, наоборот, завышенные концентрации озона и оксидов азота.

В работе была проведена оценка баланса обмена углеродом в системе “атмосфера - биосфера”. Для этого в работе были выполнены расчёты вертикальных потоков углекислого газа с использованием метода градиентных измерений. Градиентные измерения концентрации углекислого газа и метеорологических параметров были получены на территории Обсерватории “Фоновая” ИОА СО РАН в период с июля 2016 по январь 2022 г.

Long-term observation series of the methane content in the near-water atmosphere and in water in the coastal zone of Lake Baikal are analyzed. The measurements were carried out in the Baikal Atmospheric-Limnological Observatory (BALO SB RAS, which is a part of the Resource Sharing Center “Atmosfera”). A steady increase of the methane content in the atmosphere by about 12 ppb per year is observed. The average diurnal methane content in March 2021 (the last measurement cycle) was 2.012 ppm. For the period of ling-term observations, the measured partial methane pressure in the surface water always exceeded that in the atmosphere. This fact indicates that this part of Lake Baikal is a source of methane into the atmosphere. For the coastal zone, the average value of methane flux from water was 380μgСН4 m-2 day1 . The observed increased methane concentration in the near-bottom layer indicates the predominance of bottom methanogenesis. Our data show that the increment rate of dissolved methane in surface water of Lake Baikal is 0.015 μgCH4/l per year.

In this paper, we studied the interrelation between the variations in CH 4 , CO, CO 2 , NO, NO 2 , O 3 , and SO 2 concentrations, and the number concentration of aerosol with particle diameters larger than 0.4 μm, and the following meteorological parameters: air temperature, atmospheric pressure, wind direction and speed, total solar radiation and ultraviolet radiation in the wavelength range 295–320 nm, relative humidity, and partial water vapor pressure. For this, we used the air composition monitoring data (for the period 1993–2018) from the Tropospheric Ozone Research (TOR) station in the region of Tomsk Akademgorodok.

Currently, with an increase in technological progress, anthropogenic impact on the environment is increasingly apparent. Since surface waters are the most vulnerable part of the natural environment, a detailed study of water pollution is one of the urgent tasks. This article presents the results of the instrumental measurements and the assessment of the pollution of the surface waters in the littoral zone of the Barguzin and Chivyrkuy bays of Lake Baikal. To determine the degree of water pollution, we compared hydrochemical indicators with the standards of the maximum permissible concentrations. We revealed that in different parts of the Chivyrkuy Bay, water quality varies in a wide range from slightly polluted to very polluted and, in some cases, highly polluted. The waters in the Barguzin Bay can mainly be classified as slightly polluted, and only in some areas – as moderately polluted or highly polluted. According to the comprehensive water pollution index, the waters in the Chivyrkuy and Barguzin bays is assessed as conditionally polluted and conditionally pure, respectively.

Within the framework of many-year studies of the carbon cycle in the water-atmosphere system and in order to determine high-priority measures for conservation of the unique ecosystem of Lake Baikal, the specialized combined expedition was carried out in August 2019 in Barguzin and Chivyrkuy Bays of Lake Baikal. With the unique onboard instrumentation system, we have measured the gas content in the surface water and the near-water atmosphere, as well as concentrations of biogenic elements and organic matter at the sampling stations. The spatial distribution of the increased methane concentrations in the surface water of Barguzin Bay has been analyzed to determine the main direction of the Barguzin River’s water inflow into the bay. The observational data were compared with the results of scenario calculations by a large-scale model of currents in the lake. This model gives us some understanding of a general nature of water mass circulation in the bay. For modelling small-scale manifestations in the near shore zones, it is necessary to use higher resolution models for nested regions.

Starting from 2006, we conduct combined spring expeditions over the water area of Lake Baikal. These expeditions include measurements of fluorescent characteristics at different water levels from the surface down to the bottom. Direct methods for determination of biomass and chlorophyll concentration in algae are quite laborious and do not allow in situ analysis of the results. Fluorescent methods, which are fast enough, are generally indirect and should be specially justified to provide the quantitative information about biomass or chlorophyll concentration. In this study, the results of synchronous measurements are used to examine the feasibility of empirical calibration and quantitative reconstruction of the chlorophyll content from measured fluorescent characteristics.

Shipborne and ground-based enroute measurements along the southern and eastern coasts of Lake Baikal from Kultuk village to Turka village were conducted in August 15-21, 2018. This period was chosen, because in this period the recreation load on the Baikal coast is the highest and the summer peak in development of the water biota is observed. The route included ten stations with a priori different anthropogenic load. At each station, the content of carbon dioxide and methane in the atmosphere and dissolved in water, as well as their fluxes in the water-atmosphere system, were measured. Here, samples of surface and bottom water were taken, in which the pH value, the concentration of dissolved oxygen, bicarbonate, nitrate, phosphate and fluorescence characteristics were determined. It is shown that the minimum concentrations of nutrients were recorded at the Boyarskii village. The strongest water pollution was found near the coast of Novyi Enkhaluk village. Particularly this part of the coast is subjected to the highest anthropogenic impact from tourist complexes located along this coast line.

We report long-term comprehensive measurements of CO2 in the atmosphere, surface water and the major nutrients obtained for the period 2004-2018. The research was conducted at the Baikal Atmospheric and Limnological Observatory (BALO), which is located in the coastal zone of South Baikal (coordinates 51 degrees 54' N, 105 degrees 05' E). The seasonal variation of these characteristics was analyzed. For our site, during the open water period (May-December) we assessed average flux of CO2, which amounted to -155 mmol m(-2) y(-1) (sink from the atmosphere to the water surface). Carbon dioxide content in the near-water air of Lake Baikal rises with a rate of 2.46 ppm per year, which is in good agreement with the global trend. The common effect of many factors (often multi-directional), such as variability of weather conditions, hydrological processes and productivity cycles of aquatic plankton in the Baikal waters, cause strong variations in the water characteristics, which we observed in different seasons and years. Under these conditions of strong inter-annual and seasonal variability of all characteristics, trend calculations using our long-term observations did not allow us to reveal reliable tendencies of changes in surface water CO2 concentrations. (C) 2019 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.

We describe the current state and technical characteristics of Tropospheric Ozone Research (TOR) station, created 25 years ago to monitor atmospheric composition, basic meteorological variables, and other parameters. The multiyear observations showed that the air quality on the territory of Akademgorodok in Tomsk has been substantially degraded since the creation and development of the Special Economic Zone on its territory.

The spatial distribution of the partial pressures of carbon dioxide and methane in the surface water and near-water atmosphere over the Lake Baikal area (shipborne expeditions in late May-early June of 2013 and 2016–2018) is analyzed. It is found that in the zones, where the process of formation of spring homothermy begins to develop, the CO2 concentration increases and the CH4 content decreases in the surface water. The analysis of water samples at hydrological stations has shown that the vertical distribution of biogenic elements and fluorescent characteristics at these parts of the pelagic zone in the upper 200-m water layer alternates considerably.

This study continues the thorough investigation of the impact of physical, hydrological, chemical, and biological processes on the СО2 gas exchange in the water-atmosphere system at Lake Baikal. The results of measurements of the СО2 flux direction, biogenic elements, and fluorescent characteristics over the entire Baikal territory in the spring periods of 2016 (from 25.05 to 06.06.) and 2017 (25.05 to 05.06) are compared. Fluorescent characteristics were measured with a flow-through fluorimeter, whose operation is based on the principle of pulse-amplitude modulation. It is shown that most significant year-to-year differences in the analyzed characteristics are observed in the Middle Baikal region. In 2016, the surface temperature in this zone approaches 40°C, and probably the vertical exchange process manifests itself here.