Microbial processes and genesis of methane gas jets in the coastal areas of the Crimean Peninsula

Малахова, Т. В.; Канапацкий, Т. А.; Егоров, В. Н.; Malakhova, L. V.; Artemov, Yu. G.; Евтушенко, Д. Б.; Гулин, С. Б.; Пименов, Н. В.

doi:10.1134/s0026261715060053

Cited by 27 publications

(2 citation statements)

References 13 publications

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“…It should be taken into account that the presence of a cold methane degassing discharge zone in the studied area [8,15] does not exclude the possibility of organic matter local accumulations: around the site of the gas jets outlet micro-oases of life, in which biogenic organic matter is formed during the process of bacterial chemosynthesis with the participation of methane, are formed. Organic matter synthesized by methanotrophic microorganisms becomes a trophic basis for the development of benthic organism communities.…”

Section: Results and Their Discussionmentioning

confidence: 99%

Organic Carbon and Particle-Size Distribution in the Littoral Bottom Sediments of the Laspi Bay (the Black Sea)

Orekhova¹,

Ovsyany²

2020

PhO

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Purpose. The work is aimed at estimating the organic carbon abundance in the bottom sediments of the littoral zone in connection with the state of macrozoobenthos in the Sevastopol region coastal waters with different levels of the anthropogenic pressure (by the example of the Laspi Bay). Methods and Results. The samples were taken in the dynamically active coastal-shelf zone (up to the depths ~ 20 m) of the Laspi Bay in September, 2017. Two samples were taken during the 103rd cruise of R/V "Professor Vodyanitsky" (September, 2018). The geochemical composition of bottom sediments was investigated. The bottom sediments of natural humidity were analyzed in accordance with the requirements of the regulatory documents. In the sediments containing the aleurite fraction in the central part of the Laspi Bay (station 4), the organic carbon content (Сorg) increased its natural course up to 0.46 %, but did not exceed its maximum values characteristic of the similar lithological sediments in the shallow-water part of the Crimea Southern Coast (1.14 %). In the deep part of the bay occupied with the aleurite-pelitic silt, the Сorg content exceeded 2 %. Absence of the Сorg accumulation within the depths under study is conditioned primarily by the grain-size composition of the bottom sediments, the hydrodynamic factor and the morphometric features of this coastal site. Presence of a small portion of the aleurite-pelitic fraction in the bottom sediments also does not promote the organic carbon accumulation. Thus, spatial distribution of the carbon organic and inorganic forms is conditioned by the features of the matters’ lateral migration, which, in its turn, is governed by dependence of the bottom sediments’ chemical and dispersion structure upon the environmental morphodynamic conditions. Conclusions. The littoral sediments were found to be characterized by a low organic content (Сorg = 0.16 %) not exceeding the geochemical background values of the surface bottom sediments in the Black Sea shelf zones. At present, the organic matter accumulation is determined by the features of the environmental morphodynamic conditions (transition of fine particles to the deep zones) and by the dispersed composition of the bottom sediments.

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Section: Results and Their Discussionmentioning

confidence: 99%

Organic Carbon and Particle-Size Distribution in the Littoral Bottom Sediments of the Laspi Bay (the Black Sea)

Orekhova¹,

Ovsyany²

2020

PhO

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“…3В). В целом в бухте Ласпи гидроакустически и визуально зарегистрировано свыше 20 отдельных точек пузырьковых газовыделений (Malakhova et al, 2015).…”

Section: материал и методыunclassified

Биогеохимические Характеристики Мелководных Струйных Метановых Газовыделений В Прибрежных Районах Крыма В Сравнении С Глубоководными Сипами Чёрного Моря

Малахова

Егоров

Malakhova

et al. 2020

mbj

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Methane gas bubble emissions (seeps) are widespread phenomenon in the World Ocean, inter alia in Black Sea basin. The relevance of the research of methane seeps is due to their important role as a source of methane – greenhouse and environment-forming gas – for water column and atmosphere. The article presents a comparative analysis of the data from our biogeochemical 10-year studies of shallow gas seeps of the Crimean Peninsula and data on deep-sea gas seeps of the Black Sea. During 10-year period, apart from carrying out hydroacoustic research, the following parameters were determined: bubble gas component composition, methane carbon isotopic composition, microbial community structure of bacterial mats, covering gas bubble emission sites, and gas fluxes from separate seeps. During long-term monitoring, 14 separate gas bubble emission sites were detected and described in Crimean coastal areas; they were located from Cape Tarkhankut in the west of the peninsula to the Dvuyakornaya Bay in the southeast. Crimean coastal seeps were mostly of biogenic origin, with a seasonal type of gas bubble emission. Laspi Bay seeps were classified as emissions of deep gas of thermocatalytic genesis. A significant variation was recorded in values of isotopic composition of methane carbon δ13C-CH4 of bubble gas in coastal shallow areas (−94…−34 ‰), which indicates different conditions for bubble gas generation and maturation in seabed sediments. Similar to deep-sea seeps, coastal gas bubble emissions were accompanied by bacterial mats of diverse structure, with different dominating species. As shown, formation of stable bacterial biomass, usually consisting of sulfide- and sulfur-oxidizing bacteria, requires a fluid flux of reduced dissolved gases, while pointwise bubble gas discharge does not provide sufficient concentration gradients and can mechanically disrupt community structure. Various methods were used to estimate the size spectra of bubbles, as well as fluxes from separate seeps. Gas flux values varied from 1.8 L·day−1 (the Martynova Bay) to 40 L·day−1 (the Laspi Bay). The environment-forming effects, related to gas bubble emission in coastal areas, are discussed: effect of seeps on oxygen conditions in seabed sediments and in water column above gas emission sites, vertical water mixing due to gas lift effect, and fluid discharge at gas emission sites.

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Thermohaline Structure of Water Above the Microbial Mats Site at Sevastopol Marine Area

Budnikov

Ivanova

Малахова

et al. 2019

Springer Proceedings in Earth and Environmental Sciences

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Microbial processes and genesis of methane gas jets in the coastal areas of the Crimean Peninsula

Cited by 27 publications

References 13 publications

Organic Carbon and Particle-Size Distribution in the Littoral Bottom Sediments of the Laspi Bay (the Black Sea)

Organic Carbon and Particle-Size Distribution in the Littoral Bottom Sediments of the Laspi Bay (the Black Sea)

Биогеохимические Характеристики Мелководных Струйных Метановых Газовыделений В Прибрежных Районах Крыма В Сравнении С Глубоководными Сипами Чёрного Моря

Thermohaline Structure of Water Above the Microbial Mats Site at Sevastopol Marine Area

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