The bioindication of oil and gas fields is a field of geomicrobiology that is mainly devoted to the detection of hydrocarbon-oxidizing microbial indicator species or functional genes in total DNA. However, it appears promising to use the physiological properties of microorganisms detection deposit type of hydrocarbons, in particular their ability to oxidize hydrocarbons under aerobic and anaerobic conditions. In this study, the most promising approach in this area was the method used for assessing the anaerobic degradation of hydrocarbons. When comparing molecular genetics and cultured methods of bioindication, it can be concluded that molecular biomarkers of functional genes for the anaerobic destruction of hydrocarbons (masD) make it possible to separate areas with traditional and gas-hydrate types of deposits. Using cultured methods, we found that representatives of the Nocardiaceae family of the phylum Actinomycetota were tied to the areas where gas hydrates were found. The ability of aerobic and facultative anaerobic hydrocarbon-oxidizing microorganisms to anaerobically utilize hydrocarbons was determined with cultured methods. For the first time, this ability was revealed for the genera Stenotrophomonas, Psychrobacter, Micrococcus and Peribacillus. The wide distribution of this ability that we found in strains isolated from both study regions suggests its prominent role in the destruction of hydrocarbons in marine sediments.

The peculiarities of the distribution of rare-earth elements (REEs) in the surface bottom sediments in the Gulf of Tonkin (South China Sea) are considered. According to the results of granulometric analysis, the sediments are mainly represented by pelitic silt, silty pelite, and miktites. The REE contents normalized to the chondrite composition show the absence of cerium anomaly, the presence of negative europium anomaly and significant fractionation of light and heavy REEs. The values of indicator ratios La_N/Yb_N, Cr/Th, Th/Co, La/Sc, and Th/Sc indicate the predominance of rocks of intermediate and acidic composition in the erosion areas, due to which sediments were formed. The values of the Ce/La and (Fe + Mn)/Ti ratios characterize the surface sediments as typically terrigenous without the admixture of endogenous exhalative material. The Eu/Sm ratio values indicate low permeability of the sediments for upward fluid flows, which is consistent with the measured methane concentrations. The analysis of correlations indicates the dominance of the terrigenous source of REEs and that clay minerals and iron hydroxides play a significant role in the migration and accumulation of REEs.

Mud volcanoes are geological structures that transport deep-sourced fluids and gases, primarily methane and carbon dioxide, to the surface through fracture networks and fault systems. However, in certain settings, particularly within continent–ocean transition zones, the existing flux estimates are still uncertain and require regional clarification. This study presents a first quantitative, first-order assessment of methane (CH₄) and carbon dioxide (CO₂) emissions from the terrestrial Yuzhno-Sakhalinsk mud volcano (YSMV) on Sakhalin Island, Russia—a feature confined to the Central Sakhalin fault zone. Based on field research in 2023–2025, we measured free gas composition (CH₄, CO₂, He, and minor hydrocarbon components), helium isotopes, and gas fluxes from active gryphons (mud- and gas-emitting vents), combined with remote sensing data for the period of 2020–2025. The new contributions of this study are the first quantitative, first-order flux estimates. During the dormant state, the total CH₄ flux is estimated at 18.5 t yr⁻¹ and CO₂ flux at 184.1 t yr⁻¹. Unlike CH₄-dominated mud volcanoes, YSMV is strongly CO₂-dominated (60–80 vol.%), with a mantle helium contribution averaging 23.7%, confirming deep fluid sources rather than shallow biogenic or crustal radiogenic origins. Remote sensing observations under calm wind conditions (≤1.5 m s⁻¹) reveal a persistent local CO₂ anomaly of 418 ppm (8–12 ppm above background) spatially coinciding with the volcano’s location, which is qualitatively consistent with the presence of a persistent local CO₂ source. While globally the YSMV’s CH₄ emission is modest, its CO₂ output represents a sustained natural source that should be accounted for in local carbon budgets, particularly given the volcano’s proximity to populated areas.

Ссылка для цитирования: Геохимия аутигенной пиритовой минерализации бассейнов Намконсон и Фухань Южно-Китайского моря по данным рейса 88 «Академик Лаврентьев» / В.Ю. Калгин, Т.С. Якимов, С.А. Федоров, А.А. Легкодимов, Л.А. Демина // Известия Томского политехнического университета. Инжиниринг георесурсов. – 2023. – Т. 334. – № 4. – С.185-194. Актуальность. В наши дни особое внимание уделяется бассейнам, которые считаются потенциальными на наличие нефте- и газопроявлений. В этом отношении особый интерес проявляется к осадочным бассейнам Намкомсон и Фухань (Южно-Китайское море). В них установлены косвенные признаки глубинной дегазации по рифтовому разлому. Формирование нефти и газа тесно связано с образованием аутигенной сульфидной минерализации. Поэтому все больше вопросов возникает по поводу индикации проявлений нефтегазоностности провинций ассоциациями аутигенных минералов. В связи с этим изучение сульфидов от континентальных до океанических до сих пор является актуальной темой для исследований по всему миру. Цель: исследовать геохимические особенности пиритных образований из донных отложений осадочных бассейнов Намконсон и Фухань Южно-Китайского моря. Методы: масс-спектрометрия с индуктивно связанной плазмой; определение потерь после прокаливания и содержания SiO2 выполнено методом гравиметрии; атомно-эмиссионная спектрометрия с индуктивно связанной плазмой; оптическая и сканирующая электронная микроскопия; рентгеновская дифрактометрия; изотопная масс-спектрометрия. Результаты. Сульфидные образования из данного осадочного бассейна представляют собой агрегаты формы полой трубочки, размеры которых достигают максимум 5 см по длине и 5 мм по диаметру. Также обнаружены крупные сростки в виде ксеноморфных сгустков, сфероидальных образований. Сами агрегаты сложены преимущественно пиритом, присутствуют кварц и альбит. Пирит формирует глобулы и кристаллы формы октаэдра. В пиритных образованиях установлены высокие содержания кобальта (16,5...56,8 г/т), никеля (21,4...377 г/т) и молибдена (20,1...117 г/т). Цериевая аномалия составляет 0,90...0,93 г/т. Изотопные значения δ34S составляют от –32,9 до –47,0 ‰. Данные значения и построенные на их основе генетические диаграммы указывают на гидротермальное происхождение пиритных образований.

Our research deals with the possibilities of using microorganisms as bioindicators for methane ecosystems in areas with gas hydrates. We have conducted a study of the biodiversity of microorganisms and determined the physiological and biochemical properties of bacterial strains that can oxidize hydrocarbons isolated from the bottom sediments in the northern part of the Japan Sea for two areas: one with detected gas hydrates (Area 1) and one without the presence of gas hydrates (Area 2). Complex gas-geochemical, geological, and microbiological studies have been conducted in the waters of the northern Japan Sea, including the southern part of the Tatar Strait and the northern slope of Primorsky Krai. Obtained materials were gotten from marine expeditions: RV “Akademik Oparin” 54 (OP54) in September–October 2017 and RV “Akademik M.A. Lavrentyev” 81 (LV81) in May 2018. We used cultivation techniques to discover that members of the Nocardiaceae family from the Actinomycota phylum were associated with areas where gas hydrates had been detected. We found that bacteria isolated from these areas were able to ferment a wider variety of carbohydrate substrates than those obtained from non-gas hydrate areas. A positive correlation was observed between the ability of these bacteria to break down carboxylic acids and their absence from gas hydrate-rich environments.