Lev Igorevich Tribis

Microplastic pollution threatens soil health by disrupting chemical and microbial balances and impairing nutrient cycling, with effects that vary depending on soil properties. The objective of this study is to determine the effects of contamination with three types of microplastics (<5 mm)—polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET)—on the microbiological and chemical parameters of four soil types in Bulgaria: Calcic Chernozem, Vertisol, Luvisol, and Fluvisol. A controlled 180-day laboratory incubation experiment was performed, where each soil type was contaminated with microplastics at three concentrations to monitor changes in key microbiological and chemical properties. It was established that microplastics contamination suppressed abundance of key microbial groups and limited nutrient availability, inducing a state of biological and chemical imbalance in the soil. PET exerted the strongest impact on soil chemical properties, with the agrochemical properties of Fluvisol being the most sensitive to MP contamination. PE and PET had the greatest influence on microbial communities, with Vertisol and Luvisol being the most affected in this regard. PP contamination altered key metabolic processes, with the specific impact being highly dependent on soil type and most pronounced in Chernozem. Furthermore, the concentration influenced the measured parameters, with the effects varying depending on the soil type and the microplastic type. Among the factors influencing soil responses to microplastic contamination, soil type appears to be the most decisive, followed by the type of microplastic.

The key objectives of contemporary agriculture are restoring biodiversity, preserving ecosystem health, reducing the effects of climate change, and producing safe and healthy foods. Maintaining high soil fertility while reducing greenhouse gas emissions requires a precise assessment of how fertilization and crop rotation affect carbon and nutrient cycles in agroecosystems. Fertilization affects soil conditions, which alters the environment for soil microbial development and influences the number and composition of soil microbial communities, leading to changes in nutrient and carbon cycling. There is a lack of long-term experimental data on the impact of fertilizer treatments on soil CO₂ emissions, soil microbial communities, and their interactions. The novelty of this study is that it identified the fertilization effects on soil carbon sequestration, soil properties, and microbial communities in the context of a long-term fertilizer experiment in Luvic Chernozem. The fertilization treatments that were continuously pplied for 64 years under a four-crop (wheat, barley, corn, and bean) rotation were nitrogen (N), phosphorus (P), potassium (K), NP, NK, PK, NPK, and control. The chemical and microbiological soil properties and soil CO₂ emissions were monitored. The highest organic carbon content was observed under the NPK (1.42%) and NP (1.43%) treatments. N fertilizer application most significantly affected soil properties, including pH, electrical conductivity, and soil organic carbon content, altering the environment for soil microbial development and influencing the number and composition of soil microbial communities. On average, the field-measured soil C-CO₂ emissions were the most intensive under NP (2.76 kg ha⁻¹ h⁻¹), NPK (2.83 kg ha⁻¹ h⁻¹), and PK (2.51 kg ha⁻¹ day⁻¹) treatments.

A key objective of contemporary agriculture is to restore biodiversity, preserve ecosystem health, reduce the effects of climate change, and produce safe and healthy foods. Maintaining high soil fertility while reducing greenhouse gas emissions requires a precise assessment of how fertilization and crop rotation affect the carbon and nitrogen cycles in agroecosystems. In the context of a long-term fertilizer experiment on Luvic Chernozem, a monitoring of chemical and microbiological soil properties and CO2 emission was carried out. The fertilization treatments that have been continuously applied for 64 years under four-crop (wheat, barley, corn, and beans) rotation are N, P, K, NP, NK, PK, NPK, and 0. The highest organic carbon content was observed in the treatments NPK (1.42%) and NP (1.43%), and the lowest in the control (1.05%). The constant application of nitrogen as single fertilizer led to lower SOC values (1.22%). On average, CO2 emissions were the most intensive in NP (66.34 kg ha-1 day-1), NPK (67.82 kg ha-1 day-1) and PK (60.16 kg ha-1 day-1) treatments. The nitrogen fertilizer application most significantly alters soil properties including pH, EC, and SOC, which alters the environment for soil microbial development and influences the number and composition of soil microbial communities.

Introduction. In many countries, there is an additional group of pollutants - deicing materials (DIM) in winter. Salt-containing DIM is one of the factors for increasing the content of PM2.5 and PM10 in the air. The purpose was to determine the possibility of using desiccators to study the aerosol effect of liquid deicing material, identify the chemical composition in the air at spreading liquid DIM in various ways, and establish the calculated doses for conducting a toxicological experiment to study the DIM aerosol effect on the organism of warm-blooded animals. Materials and methods. A model experiment was conducted in airtight containers (desiccators) using a liquid DIM that includes NaCl and CaCl2. All chemical compounds were captured in air pumping from the desiccator into a bubbler tank with bidistilled water and then analyzed using ion chromatography. Results. When comparing the obtained results of main DIM components contained in the air inside desiccators with the maximum permissible concentrations, the excess of Cl- was detected both for the highest single concentration of 0.1 mg/m3 and for the average daily concentration of 0.03 mg/m3. When applying DIM at a dose exceeding ten times the recommended norms for liquid the DIM, an excess level of the maximum permissible concentration for chlorine (but not for sodium and calcium) is observed. Conclusion. The method of DIM studying in desiccators is indicative in terms of the choice of concentrations and studying mechanisms of reagent intake for subsequent DIM research conduction using laboratory animals.

Introduction. For the time present, the active substances of many ice-melting agents used in Moscow are technical sodium and calcium chlorides. By degree of impact of sodium chloride on the human body is characterized as a moderately dangerous substance that belongs to the 3rd hazard class. Residents of megacities who remain unprotected from the possible harmful effects of these substances need the compliance of the ice-melting product’s application with appropriate security measures. Our research focused on the presence of these substances and their accompanying components in the transit environment and determining their actual and extreme loads to prevent possible functional changes in the future traffic chain objects. Material and methods. Chloride (Cl-) and sodium (Na+) content in the snow mass samples taken from the sites adjacent to motorways in Moscow were determined using ion chromatography. Other associated elements in the ice-melting agents were detected using inductively coupled plasma mass spectrometry method (ICP-MS). Results. According to the snow mass analysis as an object of transit accumulation and distribution of ice-melting reagents, the authors ranked results and identified clusters with different degrees of contamination for many indices. Selecting the group with very high contamination enabled us determine the indices’ levels that limit the use of deicing reagents. When using sodium-chloride reagents, they are the levels of the specific electrical conductivity (SEC) ≥ 4500 µS/cm, the concentration of chloride anions (Cl- ≥ 2500 mg/l), the concentration of sodium ions (Na+) ≥1500 mg/l, the index of total contamination (Zc).

Introduction. The anti-icing materials (hereinafter - PGM), the use of which is necessary to ensure safety on the roads, enter into the soil during snow melting. In addition to the direct impact on human health, the use of PGM can affect it indirectly, worsening the state of environmental objects, including the state of the soil. According to the literature, the regular use of PGM along roads leads to the formation of man-made soil anomalies of high salt content, distributed along with the vertical and horizontal profiles. The high salt content causes an increase in the migration capacity of accompanying pollutants - heavy metals, translating them into mobile forms. The study of migration processes of toxicants is one of the hygienically significant tasks of regulation. Thus, the purpose of this study is to investigate the effect of the total load of anti-icing materials on the soil. Material and methods. The effect of the solid PGM of the nitrate group, which consists of (NН2)2СO, Mg(NO3)2 and NH4NO3, was studied with varying degrees of stress on the upper root zone of sod-podzolic and urban soils to establish their absorptive capacity and salt migration to the underlying horizons in model experiment. Results. A significant amount of calcium cations (Ca2+) was established to be contained in aqueous filtrates as compared with the control. The process of calcium leaching occurs most intensively in the anthropogenically transformed urban soil, which is more susceptible to de-icing. Thus, it can be concluded the zonal (sod-podzolic) soil to have a greater accumulating capacity for the PGM components and low buffering activity in comparison with urban soil. Considering the specific features of soil processes under the influence of the PGM components, there is a danger of secondary pollution of groundwater. In this regard, the soil quality monitoring system should take into account an integrated approach, and preventive measures for the improvement of urban soil need to be planned, providing for the inevitability of the use of GMP in the winter to ensure road safety.