Geochemical Anomalies of Frozen Ground due to Hydrocarbon Migration in West Siberian Cryolithozone

According to the study of frozen deposits in the territory south of the Taz Peninsula, geochemical processes are considered under the hydrocarbon migration from the lower productive complex. An analysis of the cryolithological structure of the frozen stratum was performed, and the composition of the gas and authigenic associations was studied. It was shown that the migration of gases is caused by shear deformations with the formation of cryogenic textures with the presence of gas-bearing ice crystallites on slip surfaces. It was found that the migration of hydrocarbons causes significant local changes in pH/Eh parameters in the frozen stratum and determines the micromosaic distribution of sulfate and iron reduction processes that lead to the formation (including microbiological processes) of various forms of iron: sulphides, carbonates and oxides

Periglacial Landforms and Fluid Dynamics in the Permafrost Domain: A Case from the Taz Peninsula, West Siberia

Most of the developing oil and gas fields in Russia are located in Arctic regions and constructed on permafrost, where recent environmental changes cause multiple hazards for their infrastructure. The blowing-up of pingos, resulting in the formation of gas emission craters, is one of the disastrous processes associated both with these external changes and, likely, with deep sources of hydrocarbons. We traced the channels of fluid migration which link a gas features reservoirs with periglacial phenomena associated with such craters with the set of geophysical methods, including common depth point and shallow transient electromagnetic methods, on an area of a prospected gas field. We found correlated vertical anomalies of acoustic coherence and electrical resistivity associated with gas chimneys in the upper 500–600 m of the section. The thickness of the ice-bonded permafrost acting as a seal for fluids decreased in the chimney zone, forming 25–50 m deep pockets in the permafrost base. Three pingos out of six were located above chimneys in the study area of 200 km2. Two lakes with parapets typical for craters were found. We conclude that the combination of applied methods is efficacious in terms of identifying this type of hazard and locating potentially hazardous objects in the given territory

Stable oxygen and hydrogen isotope compositions of the Messoyakha-1 and Pestsovoe pingo ice cores, Northwest Siberia

Two large pingos from ice cores of different origin in the continuous permafrost zone of northwest Siberia, the Messoyaha-1 pingo (10.5 m in height) and the Pestsovoe pingo (17 m in height), have been studied. Obtained distribution of stable oxygen and hydrogen isotopes in pingo ice cores allowed to understand the ice core formation. Ice formation was estimated according to the Rayleigh fractionation in a closed-system versus an open-system framework. For the Pestsovoe pingo the decrease in δ¹⁸O values with corresponding increase in dexc with depth indicates a closed system upon freezing of the lake talik from the top down. For the Messoyakha-1 pingo, the values of δ¹⁸O and δ²Н showed a weak tendency to decrease with depth, with values of dexc varying randomly. Ice that was segregated in the overlying and underlying sediments had similar values of δ¹⁸O and δ²Н and a low slope. Isotopically nonequilibrium ice formation was established for ice which had been segregated in a closed system and for ice cores formed in an open to semiclosed system. The vacuum mechanism of water suction from the surrounding lake or lake talik may have played a significant role during the formation of the upper ice core of the Messoyakha-1 pingo and its additional growth

Serotype changes and antimicrobial nonsusceptibility rates of invasive and non-invasive Streptococcus pneumoniae isolates after implementation of 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Bulgaria

The 10-valent pneumococcal conjugate vaccine (PCV10) has been included in Bulgarian Childhood Immunization Program since 2010. This study aimed to assess serotype distribution and antimicrobial resistance of 198 invasive and non-invasive Streptococcus pneumoniae strains that had been isolated in Bulgaria during 2011–2016 from patients with invasive (IPD) and non-invasive (NIPD) pneumococcal diseases. The most common invasive serotypes were 3 (10.1%), 19F (4.0%), and 7F (3.0%). A significant decrease in the proportion of invasive vaccine types (VTs) from 64.2% to 35.2% was found in comparison with pre-vaccine era. The most common serotypes among middle ear fluids were 3, 19A and 19F (5.6% each), and VTs fell down from 66.4% to 40.0% in post-PCV10 period. Among respiratory isolates, the most prevalent serotypes were some emergent serotypes such as 15A/B/C (5.0%), 19A, and 6C (4.0% each). VTs decreased significantly (16.3%) among vaccinated children compared to unvaccinated children and adults (44.0%). Two non-VTs (19A and 6C) have increased significantly more (p < 0.05) in vaccinated children than in unvaccinated patients. The rates of antibiotic nonsusceptible S. pneumoniae in Bulgaria remained high in post-PCV10 era. Among all source of isolates, antimicrobial nonsusceptibility rates were: oral penicillin – 46.5%, trimethoprim-sulfamethoxazole – 45.4%, erythromycin – 43.9%, tetracycline – 37.4%, and multidrug-resistance (MDR) was 44%. The most common MDR serotypes were 19F, 19A, 6A/C, 15A/B/C and 23A. Our results proved that PCV10 vaccination substantially reduced VTs pneumococcal IPD and NIPD. There has been a shift in the distribution of S. pneumoniae serotypes mostly in vaccinated children but also in the whole population and strong serotype-specific antibiotic resistance was observed after vaccine implementation. Therefore, it is important to continue monitoring serotype changes and pneumococcal resistance among all patient ages in addition to aid in determining the long-term effectiveness of PCV10 interventions. Keywords: Streptococcus pneumoniae, Invasive and non-invasive isolates, Serotypes, Antimicrobial nonsusceptibilit

Evaluation of engineering-geocryological conditions of the beregovoe oil and gas condensate field

Актуальность исследования обусловлена необходимостью оценки существующих инженерно-геологических условий, процессов и опасностей, а также связанных с ними рисков и воздействий в отношении предполагаемого использования участка Берегового месторождения Пуровского района Ямало-Ненецкого автономного округа. Необходимым предварительным этапом при разработке проекта обустройства нефтегазоконденсатного месторождения является анализ данных территории строительства. Цель работы: построение карты инженерно-геологических условий территории месторождения для оценки состояния и прогноза изменений инженерно-геологических условий по результатам проведенных инженерно-геологических изысканий. Объектами исследования являются компоненты геологической среды, рассматриваемые при проектировании освоения Берегового месторождения. Методы исследования: анализ материалов инженерно-геологических изысканий, детальный литолого-генетический анализ территории, учет закономерностей пространственной изменчивости основных показателей инженерно-геологических условий (состав пород, температура грунтов, характер распространения многолетнемерзлых пород, инженерно-геологические процессы). Результаты. На основе дешифрирования космоснимка территории выделено шесть типов местностей: А (озерно-болотный); Б (хасырейный); В (приречный); Г (холмисто-увалистый); Д (линейно-грядовый) и Е (техногенные грунты). Результаты полевых работ и лабораторных исследований физико-механических свойств грунтов позволили детализировать предварительную оценку инженерно-геокриологических условий. Основная часть трассы проходит по приречному типу местности В. Наиболее неблагоприятными для строительства сооружений и прокладки трубопровода являются типы местности: А (встречается локально в низинах, представлен болотами с мощностью торфа до 2,2 м) и Б (имеет широкое распространение, представлен заболоченными участками, сложенными глинистыми грунтами с отсутствием поверхностного стока), типы Г и Д по трассе не встречены. По результатам выполненных работ рекомендовано размещать площадки строительства и трассы линейных сооружений на хорошо дренированных суходольных участках распространения талых грунтов.The relevance of the research is caused by the need to assess the existing engineering geological conditions, processes, and hazards, as well as the risks and impacts related to them with respect to the intended use of the site of the Beregovoe Field of Purovsky District, Ya­malo­Nenets Autonomous Okrug. A necessary preliminary step in development of the project is the analysis of engineering-­geological data of the construction site. The main aim of the research is to create the engineering­-geological map of the deposit for assessing the situation and forecasting the changes engineering geological conditions according to the results of the performed geotechnical investigations. Objects of researches are surface features and subsurface earth materials for design and construction of the Beregovoe field exploration. Methods: the analysis of engineering­-geological surveys, detailed litholo-gical­genetic analysis of the territory, taking into account the regularities of the spatial variability of the main indicators of engineering­-geological conditions (composition of soils, their temperature, distribution of permafrost and engineering-­geological processes). Results. The authors identified six types of areas: A (lakes and marshes); B (drained lake); C (riverside); D (hilly ridge); E (linear ridge) and F (man­made soils). The results of the field works and laboratory investigations of geotechnical properties of soils allowed detailing a preliminary assessment of the engineering-­geocryological conditions. The main part of the route passes through riparian areas С. The most unfavorable for construction of facilities and pipeline are terrain types: A (found locally in the lowlands, represented by marshes with a capacity of peat to 2,2 m) and B (has wide distribution, represented by wetlands, folded clay soils with no surface runoff). The types D and E are not met on the route. We recommend placing the linear structures of pipelines on well­drained upland sites spread thawed soils

Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic

In order to investigate the link between the methane dynamics in permafrost deposits and climate changes in the past, we studied the abundance,composition and methane production of methanogenic communities in Late Pleistocene and Holocene sediments of the Siberian Arctic. We detected intervals of increased methane concentrations in Late Pleistocene and Holocene deposits along a 42 ka old permafrost sequence from Kurungnakh Island in the Lena Delta (northeast Siberia). Increased amounts of archaeal life markers (intact phospholipid ethers) and a high variety in genetic fingerprints detected by 16S ribosomal ribonucleic acid (rRNA) gene analyses of methanogenic archaea suggest presently living and presumably active methanogenic archaea in distinct layers predominantly in Holocene deposits but also in deep frozen ground at 17 m depth. Potential methanogenic activity was confirmed by incubation experiments. By comparing methane concentrations, microbial incubation experiments, gene analysis of methanogens and microbial life markers (intact phospholipid esters and ethers) to already partly degraded membrane lipids such as archaeol and isoprenoid glycerol dialkyl glycerol tetraethers (GDGT), we demonstrated that archaeol likely represents a signal of past methanogenic archaea. The archaeol signal was used to reconstruct the response of methanogenic communities to past temperature changes in the Siberian Arctic and the data suggest higher methane emissions occurred during warm periods, particularly during an interval in the Late Pleistocene. This new data on present and past methanogenic communities in the Siberian terrestrial permafrost imply that these microorganisms will respond to the predicted future temperature rise in the Arctic with increasing methane production as demonstrated in previous warmer periods