The elemental composition of near-surface aerosol in Moscow in the winter periods of 2020 and 2021 are presented according to the data of regular observations of aerosol composition at A.M. Obukhov Institute of Atmospheric Physics RAS. Reliable differences in meteorological conditions (air temperature, wind direction) of these winters are confirmed by statistical tests. The use of statistical methods made it possible to identify groups of elements with similar or opposite indicators characterizing their nature and/or processes forming their concentrations in near-surface air, in particular during the transition period from winter to spring seasons.
The seasonal variability of aerosol composition was studied according to three-year field observations in Moscow and one of its suburbs from the autumn 2019 by the autumn 2022. A high correlation has been established between the aerosol concentration of PM2.5 and PM10 fractions both in Moscow and in the suburb, as well as between these points for each fraction. Taking into account the seasons, meteorological conditions and sources, the level of aerosol pollution of near-surface atmospheric layer, typical for Moscow metropolis and the suburb, has been determined. Two identical groups of chemical elements were identified in the near-surface aerosol for the city and the suburb at any time of the year – terrigenous (Th, Al, U, La, Li, Sr, Ba, Mg, Fe, Cs, Co, Mn, Cr, K, Ca) and non-terrigenous (Mo, Cu, Zn, Pb, Sn, S, Sb, Cd, Se, Bi).
Aerosol, being one of the most variable components of the atmosphere, has a significant impact on its radiation balance and the Earth's climate [1][2][3].The magnitude of aerosol radiation forcing is determined by the concentration and optical characteristics of aerosol particles.There are various methods for studying the microphysical and optical characteristics of an aerosol, but the main tools for studying the microstructure of an aerosol in local volumes are particle counters, nephelometers, and polarimeters [4][5]. We present preliminary results of measurements within the seasonal complex aerosol experiment at Zvenigorod Scientific Station (ZSS) located in 38 km west from Moscow in July and August 2020 of the backscatter coefficient D11 using the modernized FAN, as well as the microphysical characteristics of the surface aerosol using laser and optoelectronic aerosol spectrometers. It was revealed that the value of the average D11 is significantly influenced by signal emissions associated with the passage of large particles through the working volume of the device; therefore, the value of the minimum values of D11 was taken as a reference value for further analysis of the statistics of emissions. The value of the contribution of large particles in this case strongly depended on the atmospheric situation.
We study the composition of near-surface aerosol in the center of Moscow and in its suburb (near Zvenigorod - west of Moscow) in the period 25.03-03.05.2020. The concentrations of different aerosol size-fractions, as well as the concentrations and enrichment factors of a number of chemical elements of different genesis, their correlations and particle size distributions are managed, in addition to source emissions, by long-range atmospheric transport of air masses and meteorological parameters. During the observation period, both points were in the similar meteorological and synoptic conditions, which caused high correlations of mass concentrations of different aerosol fractions between the city and the suburb. In the last days of March, the regional atmospheric transport of smoke and dust aerosols from neighboring areas with multiple biomass fires created a sharp increase in the total aerosol content and its chemical element concentrations in the air both in the city (the daily MPC value for PM10 particles was exceeded) and in the suburb. The first estimates of the spring rates of removing aerosols of different sizes and individual chemical elements from the atmosphere with air humidity increase were made for Moscow region. The conditions forming the composition of near-surface atmospheric aerosol in megapolis and in its suburb are discussed.
The elemental composition of near-surface aerosol was determined in Kislovodsk city and on Shatzhatmaz mountain plateau (North Caucasus) in 2010-2017. The accumulation coefficients of chemical elements in components of geochemical high-mountain landscape (surface aerosol, soil) show the increased concentrations of lithogenic elements typical for this region (Al, Na, Mg, Ka, Ca, Fe). In its turn, the technogenic elements (phosphorus, sulfur, heavy metals) are also available both in aerosols, and in soils at both observation points. We analyze the impacts of local anthropogenic sources and pollution transport with air masses from neighboring regions.
The results on elemental composition of the surface aerosols in Moscow region were studied from the data of the integrated autumn experiment. Elemental composition of aerosol particles in the atmosphere of Moscow сity and in the suburb in the fall 2019 under unusual weather conditions are presented. The average daily mass concentration and fractional composition are compared with synoptic and meteorological factors, as well as with local aerosol sources. Meteorological conditions and local sources play great roles in forming aerosol elemental composition variability and its mass concentration.
Aromaticity is one of fundamental characteristics of unsaturated organic molecules, which significantly determine chemical properties. By definition, aromatic molecules mast be cyclic, planar, have a complete conjugated π- electrons, and the number of π-electrons mast be 4n+2, where n is any integer number. Aromatic molecules are chemically very stable and have low reactive ability. In the contrary, anti-aromatic molecules, which have conjugated 4n π-electrons, highly unstable, preferably isomerize into aromatic composition, and demonstrate high chemical activity. In this paper, we study properties of typical aromatic and anti-aromatic compounds on the example of pentalene, phenylacetylene, and benzocyclobutadiene, and compare the change of their photochemical properties with changing the electric charge (under the single and double ionization). It was found that aromaticity of the molecules is really changing due to the loss of electrons. Dissociation reactions of pentalene, phenylacetylene and benzocyclobutadiene, as far as their cationic and dicationic forms were investigated. The effect of Coulomb repulsion in doubly ionized molecules also has been observed.
It is well known that the processes of vertical propagation and dissipation of acoustic-gravity waves (AGWs) play an important role in the realization of connections between the dynamic processes in different layers of the atmosphere. This work presents the results of lidar probing of tropospheric aerosols, performed in Kaliningrad, Russia (54°N, 20 °E). The observations used a two-wave atmospheric lidar (with wavelengths of 532 and 1064 nm), which allows investigation of properties of troposphere up to the altitudes of 10-12 km. During the observations, the intensity of the lidar signal scattered in the troposphere was determined. Measurements that were carried out in the period of 2011–2018 that made it possible to determine the features of the vertical structure and the dynamics of aerosol particles. Analysis of the results of the observations revealed an increase of the wave activity in the troposphere during the periods of passage of the solar terminator in the range from 2 to 20 minutes.
Studying the processes occurring in biological systems under irradiation is critically important for understanding the principles of working of biological systems. One of the main problems, which stimulate interest to the processes of photo-induced excitation and ionization of biomolecules, is the necessity of their identification by various mass spectrometry (MS) methods. While simple analysis of small molecules became a standard MS technique long time ago, recognition of large molecules, especially carbohydrates, is still a difficult problem, and requires sophisticated techniques and complicated computer analysis. Due to the large variety of substances in the samples, as far as the complexity of the processes occurring after excitation/ionization of the molecules, the recognition efficiency of MS technique in terms of carbohydrates is still not high enough. Additional theoretical and experimental analysis of ionization and dissociation processes in various kinds of polysaccharides, beginning from the simplest ones, is necessary. In our work, we extent previous theoretical and experimental studies of saccharides, and concentrate our attention to protonated glucose. In this article we paid the most attention to the cross-ring dissociation and water loss reactions due to their importance for identification of various isomers of hydrocarbon molecules (for example, distinguish α- and β-glucose).
Photochemical properties of carbohydrates, including mono- and polysaccharides, as well as various kinds of glycoproteins, proteoglycans, and glycolipids, take great attention last decades due to their significance for clarifying physical and chemical processes happening in biological molecules under irradiation. Understanding of excitation and ionization processes is important for interpretation of mass spectrometric (MS) experiments, which is the main instrument for quick and reliable analysis of biological samples. While polynucleotides and simple proteins can be easily studied by standard MS techniques (MALDI, ESI, and CID), carbohydrates and complicated biomolecules containing oligosaccharide residues are difficult to be ionized. Carbohydrates give a low signal yield. Their detection and analysis requires the special equipment and technology. Therefore, the development of new efficient methods for identification of carbohydrates in biological samples currently is the critical scientific and technical problem. In this work we study dissociation processes taking place in potassiated α- and β-glucose, which can be concerned as the modelling molecule for investigation of wide range of carbohydrates and carbohydrate fragments of biomolecules containing potassium ion as the ionization source. Here we compare deionization process with H2O and KOH elimination channels, as far as their competition with cross-ring dissociation processes. Potential energy surface were optimized by the density functional B3LYP/6-31G* method. Single point energy calculations in minima and transition state points were performed by G3(MP2,CCSD) ab initio method.
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