A record of volcanic eruptions over the past 2,200 years from Vostok firn cores, central East Antarctica

Introduction: The products of volcanic eruptions found in the snow, firn and ice deposits of the polar ice sheets are precious sources of information on the volcanic forcing of the climate system in the recent or remote past. On the other hand, the layers containing the traces of well-known eruptions serve as absolute age markers that help to construct the depth-age scale for the snow-firn thickness.Methods: In this study we present new records of the sulfate concentrations and electrical conductivity (ECM) from three shallow (up to 70 m depth) firn cores drilled in the vicinity of Vostok station (central East Antarctica).Results: In the non-sea-salt sulfate and ECM profiles we were able to identify 68 peaks that can be interpreted as traces of volcanic events.Discussion: 22 of these peaks can be unambiguously attributed to well-known volcanic eruptions (including Tambora 1816 CE, Huaynaputina 1601 CE, Samalas 1258 CE, Ilopango 541 CE and others), which allowed to construct a robust depth-age scale for the cores. 37 events have their counterparts in other Antarctic cores, but cannot be associated with welldated eruptions. Finally, 9 peaks do not have analogues in the other cores, i.e., they may be traces of so far unknown volcanic events. According to the newly constructed depth-age function, the deepest studied firn layers (70.20 m) are dated by 192 BCE

Ice core chemistry database: an Antarctic compilation of sodium and sulfate records spanning the past 2000 years

Changes in sea ice conditions and atmospheric circulation over the Southern Ocean play an important role in modulating Antarctic climate. However, observations of both sea ice and wind conditions are limited in Antarctica and the Southern Ocean, both temporally and spatially, prior to the satellite era (1970 onwards). Ice core chemistry data can be used to reconstruct changes over annual, decadal, and millennial timescales. To facilitate sea ice and wind reconstructions, the CLIVASH2k (CLimate Variability in Antarctica and the Southern Hemisphere over the past 2000 years) working group has compiled a database of two species, sodium [Na+] and sulfate [SO2− 4 ], commonly measured ionic species. The database (https://doi.org/10.5285/9E0ED16E-F2AB4372-8DF3-FDE7E388C9A7; Thomas et al., 2022) comprises records from 105 Antarctic ice cores, containing records with a maximum age duration of 2000 years. An initial filter has been applied, based on evaluation against sea ice concentration, geopotential height (500 hPa), and surface wind fields to identify sites suitable for reconstructing past sea ice conditions, wind strength, or atmospheric circulation

Ice core chemistry database: an Antarctic compilation of sodium and sulfate records spanning the past 2000 years

Changes in sea ice conditions and atmospheric circulation over the Southern Ocean play an important role in modulating Antarctic climate. However, observations of both sea ice and wind conditions are limited in Antarctica and the Southern Ocean, both temporally and spatially, prior to the satellite era (1970 onwards). Ice core chemistry data can be used to reconstruct changes over annual, decadal, and millennial timescales. To facilitate sea ice and wind reconstructions, the CLIVASH2k (CLimate Variability in Antarctica and the Southern Hemisphere over the past 2000 years) working group has compiled a database of two species, sodium [Na+] and sulfate [SO2− 4 ], commonly measured ionic species. The database (https://doi.org/10.5285/9E0ED16E-F2AB4372-8DF3-FDE7E388C9A7; Thomas et al., 2022) comprises records from 105 Antarctic ice cores, containing records with a maximum age duration of 2000 years. An initial filter has been applied, based on evaluation against sea ice concentration, geopotential height (500 hPa), and surface wind fields to identify sites suitable for reconstructing past sea ice conditions, wind strength, or atmospheric circulation

Source Apportionment of Particulate Matter in Urban Snowpack Using End-Member Mixing Analysis and Positive Matrix Factorization Model

The aim of this study was to identify particulate matter (PM) sources and to evaluate their contributions to PM in the snowpack of three East Siberian cities. That was the first time when the PM accumulated in the snowpack during the winter was used as the object for source apportionment study in urban environment. The use of long-term integrated PM samples allowed to exclude the influence of short-term weather conditions and anthropogenic activities on PM chemistry. To ascertain the real number of PM sources and their contributions to air pollution the results of source apportionment using positive matrix factorization model (PMF) were for the first time compared to the results obtained using end-member mixing analysis (EMMA). It was found that Si, Fe and Ca were the tracers of aluminosilicates, non-exhaust traffic emissions and concrete deterioration respectively. Aluminum was found to be the tracer of both fossil fuel combustion and aluminum production. The results obtained using EMMA were in good agreement with those obtained using PMF. However, in some cases, the non-point sources identified using PMF were the combinations of two single non-point sources identified using EMMA, whereas the non-point sources identified using EMMA were split by PMF into two single non-point sources. The point sources were clearly identified using both techniques

Source Apportionment of Particulate Matter in Urban Snowpack Using End-Member Mixing Analysis and Positive Matrix Factorization Model

The aim of this study was to identify particulate matter (PM) sources and to evaluate their contributions to PM in the snowpack of three East Siberian cities. That was the first time when the PM accumulated in the snowpack during the winter was used as the object for source apportionment study in urban environment. The use of long-term integrated PM samples allowed to exclude the influence of short-term weather conditions and anthropogenic activities on PM chemistry. To ascertain the real number of PM sources and their contributions to air pollution the results of source apportionment using positive matrix factorization model (PMF) were for the first time compared to the results obtained using end-member mixing analysis (EMMA). It was found that Si, Fe and Ca were the tracers of aluminosilicates, non-exhaust traffic emissions and concrete deterioration respectively. Aluminum was found to be the tracer of both fossil fuel combustion and aluminum production. The results obtained using EMMA were in good agreement with those obtained using PMF. However, in some cases, the non-point sources identified using PMF were the combinations of two single non-point sources identified using EMMA, whereas the non-point sources identified using EMMA were split by PMF into two single non-point sources. The point sources were clearly identified using both techniques

Revealing the Chemical Profiles of Airborne Particulate Matter Sources in Lake Baikal Area: A Combination of Three Techniques

Positive matrix factorization (PMF) is a widely used multivariate source apportionment technique. However, PMF-derived source profiles are never compared to real ones because of the absence of data on the chemical composition of source emissions. The aim of this study was to verify the validity of PMF-derived source profiles using the diagnostic ratios (DR) method and end-member mixing analysis (EMMA). The composition of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM) sampled in the air above Lake Baikal in summer and the composition of inorganic elements (IE) in PM accumulated in Lake Baikal snowpack were used as study objects. Five PAH sources and five IE sources were identified using PMF. Eight PAHs and six IEs selected from PMF-derived source profiles were recognized as eligible for calculating the DRs (species 1/(species 1 + species 2)) suitable for testing PMF results using EMMA. EMMA was based on determining whether most samples in mixing diagrams that use DR values as coordinates of source points could be bound by a geometrical shape whose vertices are pollution sources. It was found that the four PAH sources and four IE sources obtained using PMF were also identified using EMMA. Thus, the validity of the most of PMF-derived source profiles was proved

Investigation of Transport and Transformation of Tropospheric Ozone in Terrestrial Ecosystems of the Coastal Zone of Lake Baikal

Forest ecosystems play an important role in the process of removing trace gases from the atmosphere. The purpose of this work is the experimental study of the flux and rate of the dry deposition of ozone on different types of vegetation in the Baikal region. Based on the eddy covariance method and the flux gradient methods (including the aerodynamic gradient method (AGM), the modified Bowen method (MBR) and modified gradient method (MGM)) and with experimental data, the quantitative estimates of the fluxes and dry deposition velocity of ozone on the underlying surface were obtained for different environments (grasslands, forest). The average values of the dry deposition velocity of ozone (Vd) were equal to 0.37 cm/s at night (0–3 h) and 0.91 cm/s during daytime hours (12–18 h). The ozone flux (F) was 0.24 μg m–2 s–1 at night and 0.72 μg m–2 s–1 in the afternoon. The quantitative estimates of Vd and F on vegetation and in the forest show a higher absorptive capacity of forests compared to soil vegetation

Passive Sampling as a Low-Cost Method for Monitoring Air Pollutants in the Baikal Region (Eastern Siberia)

The measured concentrations of inorganic pollutants, such as ozone (2015–2018), sulfur, and nitrogen oxides (2012–2018) at air monitoring sites in the south of Eastern Siberia were sampled, following the passive sampling method, and analyzed. The spatial inhomogeneity of atmospheric gas concentrations is presented. The ozone concentration is lower in urban areas than those in rural areas and the background level. However, the nitrogen and sulfur oxide concentrations are higher in the atmosphere over the city site. The seasonal dependence of the ozone concentration was determined using its maximum (March–April) and minimum (September–October) levels. The dynamics of the nitrogen and sulfur oxide concentrations indicate that they are at their highest in December–June and their lowest in July–August. To verify the validity of the pollutant concentration measurements sampled by passive sampling, we compared our results with those obtained following the automatic and filter pack methods. A linear regression analysis and a pairwise modification of Student’s t test evaluated the concentrations of the air pollutant, sampled and measured using different methods, and they correlate well (r = 0.7–0.9). Full validation of the passive sampling method is not possible for some sites; therefore it is necessary to remove the remaining systematic errors in future work

Variability of the Chemical Composition of the Atmospheric Aerosol in the Coastal Zone of the Southern Basin of Lake Baikal (East Siberia, Russia)

The role of the atmosphere in the formation of the chemical composition and quality of water in Lake Baikal and its tributaries has been increasing in recent years. In this regard, studies of the chemical composition of the constituents of the atmosphere have an important practical application. In 2020 and 2021, we studied the chemical composition of atmospheric aerosol, one of the indicators of air pollution, in the atmosphere of the coastal zone of the southern basin of Lake Baikal compared to the data from previous years. The studies were carried out in the summer on the southwestern (Bolshiye Koty) and southeastern coast (Boyarsky). In the absence of smoke in the aerosol on the southwest coast, the concentrations of NH4+, NO3− and SO42− ions prevailed. The mean total concentration of ions at the Bolshiye Koty research station was 2.08 ± 1.26 μg/m3. The appearance of smog contributed to the growth of the total ionic concentration in the aerosol on the southwest coast to 6.4 μg/m3 in 2020 and to 17.6 μg/m3 in 2021. On the southeast coast, the minimum concentration of the total amount of ions was 3.3 μg/m3. The concentrations of Ca2+, Na+, K+, Cl−, and SO42− ions prevailed in the aerosol. Under the influence of smog, the total amount of ions increased to 34.1 μg/m3 in 2020 and to 18.6 μg/m3 in 2021. In periods of intense smoke, NH4+ and SO42− became the dominant ions in the aerosols at both stations. The contribution of NO3− ions increased. Although the effect of natural factors is periodic, they contribute significantly to the change in the chemical composition of atmospheric aerosol