Development and application of synthetic NP dispersions to prevent and extinguish forest and peat fires (Review)

Introduction. The analysis of flame retardants and extinguishing agents used for preventing and extinguishing fires in an ecosystem is carried out. It is shown that at present there are no weatherproof, environmentally friendly and cost effective extinguishing agents capable of stopping wood and peat burning. Purpose and objectives. Development of cost effective and environmentally friendly synthetic agents capable of both flame retarding and extinguishing natural combustible materials. Materials and methods. Synthetic dispersions of ammonium phosphates of two- and three-valence metals, as well as wood and peat fireproofed by them are the object of the study. Physical and chemical properties of synthesis products in comparison with their fire retarding efficiency are examined. Fireproofing, fire extinguishing, as well as physical and chemical properties of synthesized products are determined using GOST-regulated methods of thermal and chemical analysis, scanning electron microscopy and original methods. Results and discussion. The formulation of Kompleksil synthetic compound effective in extinguishing and fireproofing wood and peat is optimized using a full factorial experiment. At the same time, the inflow of volatile nitrogen containing products into the gaseous phase is identified as the dominating burning inhibition process common for natural combustible materials. The weather resistance (preservation of fireproof properties in respect of forest combustible materials at 79 mm precipitation), forest and environment enhancement (improvement of mineral nutrition conditions and growth of forest plant communities) properties of Kompleksil compound are identified. Conclusions. A cost effective synthetic compound based on natural mineral materials showing fireproofing and extinguishing efficiency when protecting forest combustible materials and peat is developed. This compound was tested in the process of extinguishing real wildfires; its weather resistance is identified, and the positive response of forest plant communities to the application of this multiple action compound is registered. The use of Kompleksil allows to reduce time expenditures and fire extinguishing agent consumption when extinguishing wildfires, which significantly reduces material damage.

Retrospective and current state of forest territories of the border areas of the Bryansk region exposed to radioactive contamination

The aim of the study is to analyze the accumulated data on the study of forest territories of the border regions of the Bryansk region that have been exposed to radioactive contamination for their involvement in economic activity, as well as the possible transfer of radioactive materials in forest fires. The area of recorded and unaccounted forests was estimated according to the “Forest Plan of the Bryansk Region for the period 2019-2028” and the results of the analysis of remote sensing data of the earth, the assessment of radiation pollution – according to the radiation surveys of the forest fund and radioecological monitoring of forests, assessment of cesium-137 content – according to radiation monitoring. In the course of the work, the dynamics of the transition of forests from the range of a high level of radioactive contamination to lower ones from 1991 to 2018 slightly changes the total area of contaminated forests by regions was revealed. Top-level values of cesium-137 content in the main types of forest combustible materials, which a dangerous factor is contributing to a significant increase in the content of radiocesium in atmospheric air and the transfer of radionuclides beyond the limits of radioactive contamination zones in a forest fire. The most radiation-hazardous is the forest litter, which contains more than 70% of the total cesium-137 reserve in forest combustible materials, the values of which reach values of 224 kBq / kg in the Krasnogorsk district of the Bryansk region. The obtained forecast of cesium-137 content in the forest litter by the zones of radioactive contamination of forests in the most polluted areas of the Bryansk region for the period up to 2046 indicates the preservation of a high degree of radioactive contamination of forests in the Krasnogorsk and Novozybkovsky districts after more than 60 years after the Chernobyl accident power plants. Due to the high class of natural fire hazard of forests in the south-west of the Bryansk region and the high risk of fires in contaminated areas, it is necessary to assess the degree of danger in the prevention and suppression of radioactive forest fires, especially criterion of the absorbed dose for workers in order to avoid the deterministic effect.

Определение плотности и интенcивности орошения лесного горючего материала перед фронтом горения при создании эффективной заградительной полосы

The results of experiments on the localization and complete cessation of flame combustion and thermal decomposition of typical forest combustible materials (on the example of pine needles and birch leaves) are presented. Before the combustion front, a specialized barrier strip was used in the form of a moistened layer of material with control of its size and retained volume of water. Necessary and sufficient conditions for the complete cessation of flame propagation and the pyrolysis front are determined. The relationships between the main parameters are established: the volume of water, the density and intensity of irrigation, the size of the water barrier, the volume of dry forest combustible material. When summarizing the experimental results, the values ​​of the rational density and intensity of irrigation of forest combustible material in front of the combustion front are highlighted. The main differences in the selection of the effective values ​​of these parameters are shown in the case of localization and cessation of flame burning and thermal decomposition of needles and leaves.