Constructed wetlands (CWs) are complicated ecosystems that include vegetation, sediments, and the associated microbiome mediating numerous processes in wastewater treatment. CWs have various functional zones where contrasting biochemical processes occur. Since these zones are characterized by different particle-size composition, physicochemical conditions, and vegetation, one can expect the presence of distinct microbiomes across different CW zones. Here, we investigated spatial changes in microbiomes along different functional zones of a free-water surface wetland located in Moscow, Russia. The microbiome structure was analyzed using Illumina MiSeq amplicon sequencing. We also determined particle diameter and surface area of sediments, as well as chemical composition of organic pollutants in different CW zones. Specific organic particle aggregates similar to activated sludge flocs were identified in the sediments. The highest accumulation of hydrocarbons was found in the zones with predominant sedimentation of fine fractions. Phytofilters had the highest rate of organic pollutants decomposition and predominance of Smithella, Ignavibacterium, and Methanothrix. The sedimentation tank had lower microbial diversity, and higher relative abundances of Parcubacteria, Proteiniclasticum, and Macellibacteroides, as well as higher predicted abundances of genes related to methanogenesis and methanotrophy. Thus, spatial changes in microbiomes of constructed wetlands can be associated with different types of wastewater treatment processes.

The seasonal changes in the contents and compositions of n-alkanes and n-methyl ketones have been studied in typical soddy-podzolic soils (Albic Retisols (Ochric)) under lime forests in the Losiny...

The results of a model laboratory experiment in which the acidic oil-polluted sand was incubated for three months in the presence of palygorskite or bentonite clays supplemented with mineral fertilizers and lime under conditions of periodic wetting and drying are presented. A reliable decrease in the total content of nonpolar and weakly polar CCl₄ extractable organic compounds and of the weakly polar compounds was established. The content of the nonpolar fraction, the amount of C₁₄–C₃₆ alkanes in its composition, and the (C₁₇ + C₁₈)/(C_i–15 + C_i–16) ratio, which was indicative of microbiological destruction of hydrocarbons, decreased significantly in the experiment with the palygorskite clay.

Research on air pollution in large cities by polycyclic aromatic hydrocarbons (PAHs) is one of the priority tasks for assessing air quality and environmental risks to public health. The chemical composition of aerosols sampled in spring (2018), fall (2019), and winter (2019–2020) at the Aerosol Complex of Moscow State University, located on the urban background territory of the Moscow Megacity, is analyzed. Sixteen priority PAH compounds were identified using gas chromatography, mass spectrometry, and high-performance liquid chromatography. The median value of the total concentration of the 16 PAHs (Σ₁₆PAH) increases from the spring season (1.43 ng/m³) to the fall season (1.68 ng/m³) and then to the winter season (2.47 ng/m³). Based on the diagnostic relationships of PAHs, the dominant contribution of transport, industrial enterprises, and the heating system to the total emissions was determined. Pollution roses indicate the location of sources of maximum concentrations of low-, medium-, and high-molecular PAHs. Pollution episodes are distinguished: in the spring of 2018 under the influence of the transport of smoke plumes of agricultural fires and in the fall of 2019 as a result of petrogenic emissions and an increase in biomass burning in the residential sector around Moscow. In the winter and fall seasons, the highest values of carcinogenic (0.45 and 0.42) and mutagenic (0.58 and 0.55) equivalents for benzo(a)pyrene were recorded in comparison with the spring season (0.26 and 0.38). The lifetime risk of developing lung cancer, calculated from the data for three seasons, is 0.5 cases per one million people.

The composition of soil, ground litter, and litterfall water extracts was studied for zones affected by gray heron nesting places and for background sites