Earth degassing andbiomass of hydrogen microorganisms
Hydrogen is a practically inexhaustible resource due to the continuous and abundant hydrogen degassing of the Earth, otherwise it is also called “Hydrogen respiration of the Earth”. [1]
Hydrogen degassing is the phenomenon of hydrogen release in a mixture with other fluid gases (most often hydrocarbons, helium and radon) in rift zones, during volcanic eruptions, from crustal faults, kimberlite pipes, some mines and wells. In many cases earthquakes of tectonic origin are accompanied by an increase in the hydrogen content in the air at the epicentre and adjacent areas. [2]
The potential of natural hydrogen in the Earth's interior has not been evaluated so far due to the existing prejudice that free hydrogen in nature is rare and in low concentrations and therefore has not attracted much attention of researchers. But in recent years, there are known cases of detection of free, not chemically bound, natural hydrogen on the continental land, usually in the areas of crustal fracture. We are talking about hydrogen in the composition of gases found in the form of free gas outlets in the water areas of reservoirs (gas griffins, bubble outlets), in gas-liquid inclusions in various rocks, in water-dissolved, oil-dissolved and other types of gases. In addition, there is a large amount of data on elevated hydrogen content in gas jets at the bottom of oceans.
Deep hydrogen reaches the Earth's surface in the form of hydrocarbons, water and as H2 gas. The lithosphere, as a dense layer of oxides, is a difficult barrier preventing hydrogen from reaching the surface. When prospecting and developing deposits, three types of rocks that do not allow hydrogen to pass through should be taken into account:
• volcanic
• salt domes
• fine-grained coal shales
As a result, gas accumulates under the "domes" of such rocks, and it enters into chemical reactions with other substances, which is accompanied by additional heat generation. Most likely, it is the presence of hydrogen that makes the asthenosphere a quasi-liquid medium. The data obtained by seismic tomography indicate that at a depth of about 100 km above the asthenosphere, numerous earthquake centres are formed and the rise of fluid and molten material is recorded. [2]
In the hydrogen escape zones in the Earth's topography, very characteristic "ring subsidence structures" are formed, which resemble saucers in shape and whose diameters vary from a few metres to several kilometres.
Images of the planet taken from space show that similar structures are present on all continents. These "circular subsidence structures" are clearly visible on space images, they appear as light rings and circles in the places of hydrogen streams and jets outlets. In intensive places of primordial gas outlets, subsidence and formation of water bodies are observed. Particularly noticeable on dry areas of land is a strip of more succulent and taller grass along the border of the circle. This is explained by the fact that the streams of molecular hydrogen coming from the Earth's interior, passing through the fertile layer, destroy the long molecules of black soil, discolouring the soil (Hydration of dark humus occurs).
Fluxes of molecular hydrogen where it leaves the Earth significantly affect soil properties.
The mechanism of influence is as follows:
Along with molecular hydrogen coming from the Earth's interior, it is also among the most important gaseous microcomponents of soil, where it is formed as a result of anaerobic decomposition of various organic residues by microorganisms. According to some data, its content in the soil air of automorphic soils is 1-8-6 % [4]. This formation of molecular hydrogen is carried out by strict and facultative anaerobic microorganisms, the main producers are primary anaerobes.
In normal microbial communities, the hydrogen concentration is very low due to interspecies transfer - one species gains energy in a reaction leading to hydrogen release, the other oxidises it with an acceptor unavailable to the first. The first organism can only exist if the hydrogen concentration is kept vanishingly small. This is a well-organised trophic system in which anaerobic organisms serve as producers of gases from decomposing organic matter, and specific groups of aerobic organisms that oxidise hydrogen prevent it from escaping from the soil air into the atmosphere. This position allowed us to consider soil as both a kind of bacterial filter and a gas system of different degrees of closedness depending on moistening conditions. [3]
Near the places of molecular hydrogen escape from the Earth's interior, the production of hydrogen microorganism biomass is much higher due to the fact that the hydrogen current through it is much higher than its possible formation by soil microflora. As it is known, soil pores are partly filled with water and partly with air. At sufficiently high concentration of organic matter, providing absorption of diffusing O2, the pores filled with water become a habitat for anaerobic microorganisms. Since the rate of gas transport is greater than that of dissolved matter, and diffusion coefficients in soil H2 at normal temperatures are 7 times higher than for CO2 and 3 times higher than for O2, it appears that H2 can serve as a transport vehicle to provide electron removal from anaerobes and thus provide decomposition of organic matter under anaerobic conditions. [3]
Soils contain a large and diverse group of hydrogen microorganism capable of utilising molecular hydrogen. This ability is determined by the presence of hydrogenases that catalyse the oxidation of molecular hydrogen. Most hydrogen microorganisms need molecular oxygen to grow. Some can grow on purely mineral media in the presence of carbon monoxide. [3]
Hydrogen oxidation belongs to chemosynthesis reactions and is one of the important inorganic energy sources capable of releasing a relatively large amount of energy (237 kJ/mol-h2). Consequently, hydrogen oxidising organisms play a key role in the ecosystem. [5]
Hydrogen microorganisms are autotrophicaerobic and anaerobic microorganism that obtain energy for growth by oxidising molecular hydrogen H2 and are able to utilise carbon dioxide CO2 as their sole source of organic carbon.
The study of hydrogen bacteria began in the laboratory of Professor Hans Schlegel, who became famous for publishing the textbook "General Microbiology", which was published in Germany in the early 1960s. But the first descriptions of them were given simultaneously by A.F.Lebedev and H.Kaserer in 1906 from enriched cultures in an atmosphere of hydrogen, oxygen and carbon monoxide, although the biological nature of the process of oxidation of molecular hydrogen in soil had been established somewhat earlier.
Hydrogen microorganisms are not a taxonomic group, but organisms united on the basis of several physiological features. Hydrogen microorganisms include representatives of 20 genera, combining Gram-positive and Gram-negative forms of different morphology, motile and immobile, spore-forming and sporeless, reproducing by fission and budding.
The number of microorganisms that can utilise hydrogen under aerobic and anaerobic conditions is enormous. Hydrogen is an attractive substrate for growth because it contains a lot of energy. It can be easily oxidised by enzymes - hydrogenases.
List of hydrogen microorganisms isolated from water sources and sea silt, sediment, etc.
AM1116 Caminibacter hydrogeniphilus
AcRS1 Desulfobacter hydrogenophilus
BSA Desulfurobacterium thermolithotrophum
DSM 654 Roseateles saccharophilus
DSM 9680 Desulfonema ishimotonii
Hy5 Desulfococcus sp.
Jade 02 Desulfonema ishimotonii
MA-48 Hydrogenibacillus schlegelii
MA-51 Hydrogenibacillus schlegelii
PL12 Desulfosarcina alkanivorans
SA 32 Herbaspirillum autotrophicum
TK-6_Hydrogenobacter Thermophilus
Z-829 Hydrogenobacter hydrogenophilus
And other microorganisms
Reference list:
1. Sibgeo Sibanalyt. (n.d.). Poiski i razvedka prirodnogo vodoroda v Vostochnoj Sibiri [Prospecting and exploration of natural hydrogen in Eastern Siberia].
2. Idabahov. (2022). Vodorodnoe dy`xanie Zemli [The Earth's hydrogen breath].
3. Sukhanova N. I., Trofimov S. Ya., Polyanskaya L. M., Larin N. V., Larin V. N. Changes in the Humus Status and the Structure of the Microbial Biomass in Hydrogen Exhalation Places. Eurasian Soil Science, February. 2013; 46 (2)
4. Zavarzin G.A. Hydrogen bacteria and carboxydobacteria. Nauka [Science], 1978
5. Nicole Adam, Mirjam Perner Microbially Mediated Hydrogen Cycling in Deep-Sea Hydrothermal Vents. Frontiers in Microbiology, Sec. Microbial Physiology and Metabolism, 23 November 2018
6. Larin V. N. Our Earth. Agar [Agar], 2005
7. Sy`vorotkin V.L. Deep earth degassing and global. Geoinformcentr [Geoinformcentr], 2002