Vol 44, No 5 (2019)

The model estimation is presented for the impact of interaction between anthropogenic and biogenic emissions of trace gases and aerosols on the mass concentration of the fine fraction of particulate matter (PM_2.5) in the central region of the European part of Russia. The numerical study is performed with the CHIMERE chemistry transport model taking into account the formation of secondary organic aerosol from the oxidation of semivolatile organic compounds. The simulation results are in agreement with data of PM_2.5 measurements at the Mosekomonitoring stations in Moscow. It is shown that the anthropogenic-biogenic interaction results in the growth of PM_2.5 concentration. Its relative value varies within the analyzed region from several percent to several tens of percent and leads to the considerable (by 1.5 times) increase in the number of episodes in which average daily PM_2.5 concentration exceeds the maximum permissible concentration accepted in Russia. It is found that the revealed increase in the number of such episodes is mainly caused by the accelerated formation of biogenic secondary organic aerosol in the presence of anthropogenic air pollution which accounts (on average over the region and season) for ∼60% of its surface mass concentration.

The results of studying the concentration and composition of aerosol particles washed out by rainfalls in the coastal zone of the southeastern Baltic Sea are presented. Investigations were carried out in 2008–2015. It is shown that aerosol material is represented by mineral, biogenic, and anthropogenic particles, and its average concentration in rainwater samples is 5.0 mg/l. Mineral particles are found in all samples, their maximum content is detected in summer. It is noted that biogenic material in the form of plant fibers, detritus, spores, and pollen prevailed in spring and summer. The highest concentration of anthropogenic particles is registered in autumn. The dominating particles are soot, fly ash, and combustion spheres released to the atmosphere from metallurgical and mining enterprises and thermal power plants.

The transport of volcanic aerosol in the atmosphere after the eruptions of the Grimsvotn and Nabro volcanoes in 2011 is analyzed using the method of Lagrangian particle trajectories. It was impossible to identify volcanic aerosol after the Grimsvotn eruption using data of lidar observations over Tomsk and Vladivostok against the existing background aerosol. At that time there was strong horizontal mixing in the Northern Hemisphere atmosphere. Volcanic aerosol formed after the Nabro eruption was clearly manifested in the form of aerosol scattering peaks over Vladivostok and Tomsk. This is proved by data of the CALIPSO space lidar and by the satellite observations of sulfur dioxide with GOME-2. The dynamics of the eruptive aerosol cloud formation over the Northern Hemisphere is traced.

The effects of dredging and dumping on methane concentration in water and bottom sediments of the Taganrog Bay (the Sea of Azov) are studied. It is shown that dredging operations are accompanied by the inflow of methane deposited in soil to the water column. This inflow is associated with the resuspension of soils as a result of their loosening, lifting, and loading by the dredger to the barge as well as during their discharge to underwater piles and further erosion and separation of dumping material by waves and seabed currents. In addition to the increase in methane emission to the atmosphere, this is accompanied by a negative impact on the oxygen regime due to the microbial oxidation of methane and other organic and inorganic substances which arrived during soil resuspension. However, due to a relatively small area of the seabed affected by dredging and occupied by underwater dumps as well as due to the active hydrodynamics of waters in general, their influence on methane concentration in water and bottom sediments of the Taganrog Bay is insignificant.