Hydrocarbon-based rocket fuels, particularly kerosene grades T-1 and RG-1 used during launch vehicle operations, represent a persistent source of soil contamination in areas impacted by rocket stages. This study quantitatively evaluates the response and recovery dynamics of soil microbial communities in Calcisol (Loamic) soils from the U-25 impact area near the “Baikonur” Cosmodrome (Kazakhstan) under controlled kerosene contamination. Eleven soil samples were monitored over 90 days, including one uncontaminated control and ten samples exposed to increasing concentrations of T-1 or RG-1 (100–15,000 mg/kg). Microbial indicators included total microbial count, actinomycetes, microscopic fungi, and spore-forming bacteria, expressed as CFU/g (mean ± SD, n = 3). Acute exposure caused significant reductions in total microbial abundance (28–58%) and microscopic fungi (43–75%, p ≤ 0.05), indicating pronounced short-term toxicity. By Day 90, bacterial and actinomycete populations exhibited partial to complete recovery, with some treatments exceeding control values, suggesting metabolic adaptation and hydrocarbon utilization. In contrast, fungal populations remained consistently suppressed throughout the experiment, indicating prolonged ecological stress. No strict dose–response relationship was observed, highlighting the influence of soil physicochemical properties on microbial resilience and hydrocarbon bioavailability. These findings identify microscopic fungi as the most sensitive indicators of kerosene contamination, suggesting that indigenous bacterial and actinomycete communities play a key role in natural attenuation. The results provide quantitative thresholds relevant for environmental monitoring and support the development of microbiologically informed bioremediation strategies in areas impacted by rocket launches.

The study is devoted to assessing the influence of various concentrations of hydrocarbon rocket fuels in the soil, expressed in the quantitative and qualitative composition of the main representatives of the soil biocenosis and enzyme activity. For this purpose, microbiological studies of the qualitative and quantitative composition of soil microflora were carried out in 11 soil samples treated with rocket hydrocarbon fuel grades T-1 and RG-1, with codes K1, T-1-1, T-1-2, T-1 -3, T-1-4, T-1-5, RG-1-1, RG-1-2, RG-1-3, RG-1-4, RG-1-5. As a result of scientific research, in most experimental groups there was a decrease in the number of the main soil representatives of microorganisms, which may be a consequence of exposure to hydrocarbons. Исследование посвящено оценке влиянию различных концентраций углеводородных ракетных топлив в почве, выраженное в количественном и качественном составе основных представителей почвенного биоценоза и активности ферментов. Для этого проведены микробиологические исследования качественного и количественного состава почвенной микрофлоры в 11-ти образцах почвы, обработанных ракетным углеводородным топливом марки Т-1 и РГ-1, с шифрами К1, Т-1-1, Т-1-2, Т-1-3, Т-1-4, Т-1-5, РГ-1-1, РГ-1-2, РГ-1-3, РГ-1-4, РГ-1-5. В результате проведенных научных исследований, в большинстве экспериментальных групп наблюдалось снижение численности основных почвенных представителей микроорганизмов, что может являться следствием воздействия углеводородов. Зерттеу топырақ биоценозының негізгі өкілдерінің сандық және сапалық құрамымен және ферменттердің белсенділігімен көрсетілген топырақтағы көмірсутекті зымыран отындарының әртүрлі концентрациясының әсерін бағалауға арналған. Ол үшін К1, Т-1-1, Т-1-2, Т-1-3, Т-1-4, Т-1-5, РГ-1-1, РГ-1-2, РГ-1-3, РГ-1-4, РГ-1-5 шифрларымен Т-1 және РГ-1 маркалы зымырандық көмірсутекті отынмен өңделген топырақтың 11 үлгісінде топырақ микрофлорасының сапалық және сандық құрамына микробиологиялық зерттеулер жүргізілді. Жүргізілген ғылыми зерттеулердің нәтижесінде эксперименттік топтардың көпшілігінде микроорганизмдердің негізгі топырақ өкілдерінің санының төмендеуі байқалды, бұл көмірсутектердің әсерінен болуы мүмкін.

Reserving and restoring soil fertility is one of the key tasks of agricultural science, especially under increasing anthropogenic pressure. In areas exposed to hydrocarbon pollution, including rocket fuel, disturbances occur in microbiological processes that determine the stability of agroecosystems. Assessment of soil biological and enzymatic activity makes it possible to determine the degree of its degradation and the prospects for agricultural use. The aim of this study was to investigate the effect of T-1 and RG-1 kerosene on the microbial community and enzymatic activity of brown soils collected in the area of the Soyuz rocket stage fall. The objectives included determining catalase, protease, cellulase, and dehydrogenase activity of microorganisms in dynamics (1st and 90th days of the experiment), as well as establishing the dose-dependent effect of hydrocarbon pollution. The methodology was based on classical microbiological and biochemical approaches, including in vitro tests for enzymatic activity and spectrophotometric determination of dehydrogenases. The results showed that at fuel concentrations above 500 mg/kg there was a marked decrease in soil microorganisms and biological activity, indicating a critical level of toxicity for agroecosystems. By the 90th day, the suppression of enzymatic activity persisted, although part of the microbial community demonstrated resistance to contamination. The practical significance of the study lies in the use of identified indicators for environmental standardization, monitoring of agricultural soils, and predicting the consequences of pollution for productivity. The contribution of the work is the clarification of threshold concentrations of hydrocarbons affecting soil biota, which is essential for agroecology and sustainable land use.

The scientific study is devoted to the assessment of phytotoxic effects of petroleum products, in particular hydrocarbon rocket fuel (HCF), on plants. Under laboratory conditions, radish (Raphanus sativus L. var. sativus) was used as a test subject. The reason for the work was the necessity of ecological assessment of soils contaminated in the areas where rocket carrier parts fall.The main task was to determine the relationship between the degree of soil contamination by HCM and changes in morphophysiological parameters in the indicator plant. Five soil variants were used in the study: three experimental ones with HCV content in concentrations of 100, 500 and 1000 mg/kg, as well as two control samples – a standard artificial soil reference (ASR) and soil from a real contaminated area (CA). Biotesting was carried out for six weeks. During the experiment, germination, stem and root lengths of seedlings were recorded and toxicity indices were calculated.The results demonstrated the depressing effect of UHG on plant development and seed germination. At minimum concentrations of 100 mg/kg, only a slight reduction in shoot and root length was observed. However, when the concentration was increased to 500 and 1000 mg/kg, the negative effect became more pronounced: seed germination decreased to 40% and 25%, respectively, and the length of stems and roots decreased 2-4 times compared to control samples.The observed changes clearly indicate the dose-dependent nature of UHG toxicity. The obtained data are of practical value for the development of pollution assessment standards, environmental monitoring and planning of measures for the restoration of the affected territories.