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Dr.Mann, this is called SCIENCE, not conspiracy theory, even if it is from Putin's Russia.
Of course these are Putin's agents!
Methane
in Gas Shows from Boreholes in Epigenetic Permafrost of Siberian
Arctic
29
January, 2019
1 . Institute
of Physicochemical and Biological Issues in Soil Science of the
Russian Academy of Sciences, Pushchino, Moscow Oblast 142290, Russia
2 . Department
of Earth Sciences, Vrije University of Amsterdam, 1081 HV Amsterdam,
The Netherlands
3 . Department
of Microbiology, University of Tennessee, Knoxville, TN 37996, USA
4 . West-Siberian
Filial, Trofimuk Institute of Petroleum Geology and Geophysics of
Siberian Branch of Russian Academy of Sciences, Tyumen 625026, Russia
5 . Geophysical
Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
6. Industrial
University of Tyumen, Tyumen 625000, Russia
7 . Faculty
of Biology, Lomonosov Moscow State University, Moscow 119991, Russia
8 . Center
of Forest Ecology and Productivity of the Russian Academy of
Sciences, Moscow 117234, Russia
*
Author
to whom correspondence should be addressed.
Received:
15 October 2018 / Accepted: 24 January 2019 / Published: 29 January
2019
Abstract
:
The
gas shows in the permafrost zone represent a hazard for exploration,
form the surface features, and are improperly estimated in the global
methane budget. They contain methane of either surficial or
deep-Earth origin accumulated earlier in the form of gas or gas
hydrates in lithological traps in permafrost. From these traps, it
rises through conduits, which have tectonic origin or are associated
with permafrost degradation. We report methane fluxes from 20-m to
30-m deep boreholes, which are the artificial conduits for gas from
permafrost in Siberia. The dynamics of degassing the traps was
studied using static chambers, and compared to the concentration of
methane in permafrost as analyzed by the headspace method and gas
chromatography. More than 53 g of CH4 could be released to the
atmosphere at rates exceeding 9 g of CH4 m−2 s−1from a
trap in epigenetic permafrost disconnected from traditional
geological sources over a period from a few hours to several days.
The amount of methane released from a borehole exceeded the amount of
the gas that was enclosed in large volumes of permafrost within a
diameter up to 5 meters around the borehole. Such gas shows could be
by mistake assumed as permanent gas seeps, which leads to the
overestimation of the role of permafrost in global warming.
fluxes
of CH4; epigenetic cryogenesis; cryogenic transport; permeability of
permafrost; methane accumulations; methane-hydrates; terrestrial
seeps; pingo drilling
1. Introduction
The
most recent estimation of the global methane budget includes the
following listed sources of methane, in order of decreasing
significance: the natural wetlands, geological sources (including
oceans), freshwater sources (lakes and rivers), hydrates, and
permafrost [1].
Permafrost, with its budget of 1 Tg CH4 yr−1, is the weakest
source on this list today, and is considered to be more important in
the near future. The thawing of permafrost provides a substrate and
creates a favorable environment for the bacterial production of
methane in wetlands and lakes [2].
It also provides an input of methane to the carbon cycle from the
degradation of gas hydrates, the release of gas from coal beds,
traditional gas reservoirs, dispersed or locally accumulated methane
in permafrost, and other geological sources [3,4,5].
Geological sources globally emit about 54 (33-75) Tg CH4 yr−1 [1],
which is four times less than natural wetlands. However, being mostly
point sources, they are usually stronger.
The
geological sources in the permafrost zone usually deliver methane to
the surface through conduits, ascending from deep horizons through
the permeable strata related to faults, taliks, and deposits with a
low degree of saturation by ice [6].
The conduits reaching the ground surface and continuously emitting
methane are usually referred to as seeps. The capacity and
variability of the seeps as assessed by observations both at the
local and regional scale fully rely on different land classifications
for making larger-scale extrapolations [3,4,7].
Terrestrial
seeps in Alaska, which are mostly associated with lakes, create the
flux of methane from deep sources as large as 0.2 - 4.5 g
CH4 m−2 yr−1 (3.7 g CH4 m−2yr−1 average)
of lake surface, and has a strong variation between different
sub-regions. About twice as much is emitted from thawing permafrost
itself within lake or river-closed taliks [3].
A similar study conducted in northeastern Siberia revealed emissions
of 33.7 g CH4 m−2 yr−1 of lake surface and
attributed them solely to microbial decomposition in thaw lakes [8].
The latest study from the East Siberian Sea shelf reports the surface
emission of 49.1 g CH4 m−2 yr−1 tracked from the
sea bottom at a hotspot (area with high density of seeps) of 18,400
km2 [9].
Earlier similar seeps were associated with the decomposition of
sub-permafrost gas hydrates due to permafrost degradation on the
shelf [4].
When the studies did not rely on the ebullition as a seep indicator, the findings of terrestrial seeps or gas shows were occasional, unless the methane seep resulted in the surficial forms as large as the Yamal crater. The latter is a gas blowout surface feature in continuous permafrost as evidenced by the elevated methane concentration in the air inside the Yamal crater [10], measured after an explosion. That gas accumulation happened through either cryogenic processes [5,11,12], the destabilization of the gas-hydrate layer [13], or ascending deep gases [14].
More often, the methane emits from boreholes causing the ebullition of drilling mud, drill kicks, or even fire [12,13,15]. Reviews of drilling reports documenting the gas shows provided a view on the broad geography of the phenomenon of gas shows from the topmost permafrost horizons in many regions of the Siberian Arctic. The gas shows’ dynamics that have been studied in West Siberia provided data that they originated from methane accumulations at depths between 28–150 m. The emission of methane lasted from a few days to several months, gradually decreasing from the highest initial gas flux rate ranging from about 28 kg CH4 day−1 to 10,000 kg CH4day−1 [12]. Another study reported methane concentrations reaching 77.5% vol. of borehole for several boreholes along the coast and in the shallow shelf of the East Siberian Sea [16].
A borehole acts as a conduit or a chimney, which is similar to natural disturbances or permeable sediments delivering gas from a source or lithological trap to the surface. Previous studies showed that epigenetic permafrost always contains methane in an average concentration of 2.7 mg CH4 m−3 (up to 47.4 g CH4 m−3) of frozen sediment as opposed to syngenetic permafrost, which in most cases did not have any detectable methane [17,18]. High concentrations of methane in permafrost deposits were found in redeposited and refrozen sediments of drained thaw lake basins in Central Yakutia [19], whereas moderate concentrations were detected in loams and the segregation ice of marine deposits on the Yamal Peninsula [20]. Methane in permafrost could be produced at temperatures below zero by methanogenic archaea [21], and it could be converted to interpore gas hydrate [22]. Methane in unfrozen sediments could move for several meters due to the freezing of the sediments via the mechanism of cryogenic transport and become accumulated locally in lithological traps [5,12]. Traps tend to be composed of coarse-grained sediments and have high active porosity [13].
A gas show should not be called a seep unless it has a signature of a deep source [7]. The most common signatures are the concentration of another gas (alkanes, CO2, He, H2, etc.) and the isotopic composition. If methane has δ13C < −60‰, it could be in most cases considered biogenic [23]. However, exceptions are not rare, especially with early mature natural gas [24]. The gas shows with the value of δ13C as low as –87‰, and values from –60‰ to –65‰ were reported for 10 gas-bearing fields in West Siberia at depths below 700 m [25]. The gas from shallower permafrost studied in Russia and Canada, which was both degassed from sediments [17,20] and emitted from accumulations [5,12,26], was mostly biogenic. Methane seeps in Alaska were reported to be thermogenic and of mixed origin [3], which was strongly distinct from the surficial methane sources in closed talik. Recently discovered crater-like methane seep in the Canadian High Arctic constantly emits methane of thermogenic origin [27]. However, the isotopic effects of source depletion and/or the process of oxidation could make the biogenic methane in the specific environment look isotopically thermogenic [23]. So, the isotopic composition alone is not an ultimate indicator, and the complex understanding of environmental conditions of methane formation, migration, accumulation, and degradation are always necessary for genetic interpretations.
Our review above shows that emissions from permafrost and sub-permafrost sources are poorly quantified compared to superficial methane fluxes. This might be the reason for their improper classification, because the physical forms and temporary locations of methane find themselves in the list of natural sources [1]. The gas-hydrates or permafrost could not be listed as separate sources in the methane budget, due to representing the cases of either geological or wetland sources, depending on the genesis of methane. Improper classification reduces the quality of extrapolations and forecasts. We hypothesized that there is a link between the gas shows, gas accumulations, methane hydrates, and dispersed methane in permafrost. In this paper, we attempt to find and explain these links based on our findings of the methane shows in epigenetic permafrost. We also analyze the dynamics of methane emission over time, and discuss the possible sources of methane accumulation and its concentration in the upper 30 m of permafrost on watersheds, lake depressions, and pingos on several sites in the Siberian Arctic.
1 . Institute
of Physicochemical and Biological Issues in Soil Science of the
Russian Academy of Sciences, Pushchino, Moscow Oblast 142290, Russia
2 . Department
of Earth Sciences, Vrije University of Amsterdam, 1081 HV Amsterdam,
The Netherlands
3 . Department
of Microbiology, University of Tennessee, Knoxville, TN 37996, USA
4. West-Siberian
Filial, Trofimuk Institute of Petroleum Geology and Geophysics of
Siberian Branch of Russian Academy of Sciences, Tyumen 625026, Russia
5 . Geophysical
Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
6 . Industrial
University of Tyumen, Tyumen 625000, Russia
7 . Faculty
of Biology, Lomonosov Moscow State University, Moscow 119991, Russia
8 . Center
of Forest Ecology and Productivity of the Russian Academy of
Sciences, Moscow 117234, Russia
*
Author
to whom correspondence should be addressed.
Received:
15 October 2018 / Accepted: 24 January 2019 / Published: 29 January
2019
Abstract:
The
gas shows in the permafrost zone represent a hazard for exploration,
form the surface features, and are improperly estimated in the global
methane budget. They contain methane of either surficial or
deep-Earth origin accumulated earlier in the form of gas or gas
hydrates in lithological traps in permafrost. From these traps, it
rises through conduits, which have tectonic origin or are associated
with permafrost degradation. We report methane fluxes from 20-m to
30-m deep boreholes, which are the artificial conduits for gas from
permafrost in Siberia. The dynamics of degassing the traps was
studied using static chambers, and compared to the concentration of
methane in permafrost as analyzed by the headspace method and gas
chromatography. More than 53 g of CH4 could be released to the
atmosphere at rates exceeding 9 g of CH4 m−2 s−1from a
trap in epigenetic permafrost disconnected from traditional
geological sources over a period from a few hours to several days.
The amount of methane released from a borehole exceeded the amount of
the gas that was enclosed in large volumes of permafrost within a
diameter up to 5 meters around the borehole. Such gas shows could be
by mistake assumed as permanent gas seeps, which leads to the
overestimation of the role of permafrost in global warming.
fluxes
of CH4; epigenetic cryogenesis; cryogenic transport; permeability of
permafrost; methane accumulations; methane-hydrates; terrestrial
seeps; pingo drilling
1. Introduction
The
most recent estimation of the global methane budget includes the
following listed sources of methane, in order of decreasing
significance: the natural wetlands, geological sources (including
oceans), freshwater sources (lakes and rivers), hydrates, and
permafrost [
1].
Permafrost, with its budget of 1 Tg CH4 yr−1, is the weakest
source on this list today, and is considered to be more important in
the near future. The thawing of permafrost provides a substrate and
creates a favorable environment for the bacterial production of
methane in wetlands and lakes [2].
It also provides an input of methane to the carbon cycle from the
degradation of gas hydrates, the release of gas from coal beds,
traditional gas reservoirs, dispersed or locally accumulated methane
in permafrost, and other geological sources [3,4,5].
Geological sources globally emit about 54 (33-75) Tg CH4 yr−1 [1],
which is four times less than natural wetlands. However, being mostly
point sources, they are usually stronger.
The
geological sources in the permafrost zone usually deliver methane to
the surface through conduits, ascending from deep horizons through
the permeable strata related to faults, taliks, and deposits with a
low degree of saturation by ice [
6].
The conduits reaching the ground surface and continuously emitting
methane are usually referred to as seeps. The capacity and
variability of the seeps as assessed by observations both at the
local and regional scale fully rely on different land classifications
for making larger-scale extrapolations [3,4,7].
Terrestrial
seeps in Alaska, which are mostly associated with lakes, create the
flux of methane from deep sources as large as 0.2 - 4.5 g
CH4 m−2 yr−1 (3.7 g CH4 m−2yr−1 average)
of lake surface, and has a strong variation between different
sub-regions. About twice as much is emitted from thawing permafrost
itself within lake or river-closed taliks [
3].
A similar study conducted in northeastern Siberia revealed emissions
of 33.7 g CH4 m−2 yr−1 of lake surface and
attributed them solely to microbial decomposition in thaw lakes [8].
The latest study from the East Siberian Sea shelf reports the surface
emission of 49.1 g CH4 m−2 yr−1 tracked from the
sea bottom at a hotspot (area with high density of seeps) of 18,400
km2 [9].
Earlier similar seeps were associated with the decomposition of
sub-permafrost gas hydrates due to permafrost degradation on the
shelf [4].
When
the studies did not rely on the ebullition as a seep indicator, the
findings of terrestrial seeps or gas shows were occasional, unless
the methane seep resulted in the surficial forms as large as the
Yamal crater. The latter is a gas blowout surface feature in
continuous permafrost as evidenced by the elevated methane
concentration in the air inside the Yamal crater [10],
measured after an explosion. That gas accumulation happened through
either cryogenic processes [5,11,12],
the destabilization of the gas-hydrate layer [13],
or ascending deep gases [14].
More
often, the methane emits from boreholes causing the ebullition of
drilling mud, drill kicks, or even fire [
12,13,15].
Reviews of drilling reports documenting the gas shows provided a view
on the broad geography of the phenomenon of gas shows from the
topmost permafrost horizons in many regions of the Siberian Arctic.
The gas shows’ dynamics that have been studied in West Siberia
provided data that they originated from methane accumulations at
depths between 28–150 m. The emission of methane lasted from a few
days to several months, gradually decreasing from the highest initial
gas flux rate ranging from about 28 kg CH4 day−1 to
10,000 kg CH4day−1 [12].
Another study reported methane concentrations reaching 77.5% vol. of
borehole for several boreholes along the coast and in the shallow
shelf of the East Siberian Sea [16].
A
borehole acts as a conduit or a chimney, which is similar to natural
disturbances or permeable sediments delivering gas from a source or
lithological trap to the surface. Previous studies showed that
epigenetic permafrost always contains methane in an average
concentration of 2.7 mg CH4 m−3 (up to 47.4 g CH4 m−3)
of frozen sediment as opposed to syngenetic permafrost, which in most
cases did not have any detectable methane [
17,18].
High concentrations of methane in permafrost deposits were found in
redeposited and refrozen sediments of drained thaw lake basins in
Central Yakutia [19],
whereas moderate concentrations were detected in loams and the
segregation ice of marine deposits on the Yamal Peninsula [20].
Methane in permafrost could be produced at temperatures below zero by
methanogenic archaea [21],
and it could be converted to interpore gas hydrate [22].
Methane in unfrozen sediments could move for several meters due to
the freezing of the sediments via the mechanism of cryogenic
transport and become accumulated locally in lithological traps
[5,12].
Traps tend to be composed of coarse-grained sediments and have high
active porosity [13].
A
gas show should not be called a seep unless it has a signature of a
deep source [7].
The most common signatures are the concentration of another gas
(alkanes, CO2, He, H2, etc.) and the isotopic composition. If
methane has δ13C < −60‰, it could be in most cases considered
biogenic [23].
However, exceptions are not rare, especially with early mature
natural gas [24].
The gas shows with the value of δ13C as low as –87‰, and values
from –60‰ to –65‰ were reported for 10 gas-bearing fields in
West Siberia at depths below 700 m [25].
The gas from shallower permafrost studied in Russia and Canada, which
was both degassed from sediments [17,20]
and emitted from accumulations [5,12,26],
was mostly biogenic. Methane seeps in Alaska were reported to be
thermogenic and of mixed origin [3],
which was strongly distinct from the surficial methane sources in
closed talik. Recently discovered crater-like methane seep in the
Canadian High Arctic constantly emits methane of thermogenic origin
[27].
However, the isotopic effects of source depletion and/or the process
of oxidation could make the biogenic methane in the specific
environment look isotopically thermogenic [23].
So, the isotopic composition alone is not an ultimate indicator, and
the complex understanding of environmental conditions of methane
formation, migration, accumulation, and degradation are always
necessary for genetic interpretations.
Our
review above shows that emissions from permafrost and sub-permafrost
sources are poorly quantified compared to superficial methane fluxes.
This might be the reason for their improper classification, because
the physical forms and temporary locations of methane find themselves
in the list of natural sources [
1].
The gas-hydrates or permafrost could not be listed as separate
sources in the methane budget, due to representing the cases of
either geological or wetland sources, depending on the genesis of
methane. Improper classification reduces the quality of
extrapolations and forecasts. We hypothesized that there is a link
between the gas shows, gas accumulations, methane hydrates, and
dispersed methane in permafrost. In this paper, we attempt to find
and explain these links based on our findings of the methane shows in
epigenetic permafrost. We also analyze the dynamics of methane
emission over time, and discuss the possible sources of methane
accumulation and its concentration in the upper 30 m of permafrost on
watersheds, lake depressions, and pingos on several sites in the
Siberian Arctic.
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