Content of molecular hydrogen in the bottom section
of ice sheet near Vostok Station: first results of studies
of ice cores from borehole 5G-1N
Chetverikov Yu. О.1
Ezhov V.F.1, Lipenkov V.Ya.2, Klyamkin S.N.3, Eliseev А.A.3, Aruev N.N.4,
Fedichkin I. L.4, Tyukaltcev R.V.4, Dubenskiy B. M.5, Yasinetckiy A.I.5
1
PNPI, St. Petersburg
2 AARI, St. Petersburg
3 MSU, Moscow
4 IPTI, St. Petersburg
5 CFTI «ANALYTIC» St. Peterburg
Tectonic activity of bottom of lake Vostok
and light gases in the lake
Gases, throw into the lake in process of tectonic
activity:
Radioactive-decay gases:
He – до 0.04% volume of ground water
Ar; Rn
Thermal decomposition gases:
CO2(CO); SO2(SO3); Н2S; HCl; HF
Н2
Hydrogen in ice
Chemosynthesis of the thermal spring is
the basis of life at the bottom of deep
water reservoir
Synthesis of hydrogenobacter
thermophilus bacteria:
4H2+CO2 →CH4+2H2O
of thermophilic hydrogen-oxidizing
* Observation
bacteria from the depths of the glacier 3561 and 3608
meters. [1] It is known that these bacteria live in the
hydrogen content is 25 times higher, than the value in
equilibrium with the atmosphere [2]
concentrations of hydrogen at the base of the
** High
Greenland glacier[3]
[1] S.А.Bulat et.al, International Journal of Astrobiology, 3, 1, p 1-12 (2004)
[2] H. Francis et. al, Letters to nature, 415, 312-315 (2002)
[3] В.С.Сhristner et. al, Polar biol., 35, 11, 1735(2012)
The penetration of light gases in Glacier
Diffusion of gas into ice
Lpen=sqrt(6D tLAKE)
LPEN- the depth of penetration of gas;
D- gas diffusion coefficient;
tLAKE- time of glacier location above the lake
DH2= 2*10-8 m2/sec [1] LPEN(DH2;t=40тыс.лет)=400 m
DHe=10-9 m2/sec [2]
LPEN(DHe;t=40тыс.лет)=93 m
Model of a uniform distribution of the gas in the lake under
the glacier
The flow of the glacier
Depth concentration profile
in the borehole 5G
СHe(lake)
3535 3770
3435
СH2(lake)
3270
[1] H.L. Strauss, Z. Chen, C.K. Loong, J. Chem. Phys. 101, 7177 (1994)
[2] K.Satoh, T. Uchida, T. Hondoh, S. Mae, Proc. NIPR Symp. Polar Meteorol. Glaciol. 10, 73-81 (1996)
H(м)
Alleged place of occurrence
content and depth profile of the light gases
Source of gas at the interface ice-water-to-shore
Gas trail
СHe(lake)
3535 3770
3448
Prospective icebound space of
hydrogen-oxidizing
bacteria
* *
Center of gas trail
СH2(lake)
3235
H(м)
Depth of drilling at this year
The source of gas close to the dome of subglacial island
3608 3770
СHe(lake)
3521
* *
СH2(lake) 3208
H(м)
Dynamics of degassing
and method of sampling
The model of gas adsorption from an
cylinder[1,2]:
Sampler
2
0,01
Ice
core
Model of degassing of ice cylinder with
dimension of d = 100 mm, h = 1000 mm,
previously saturated with a gas
Part of
desorbed gas (arb. un.)
Vostok Ice 1
Empty cell
Usual Ice
Vostok Ice 2
IdismmHg*0.025*l/110*sm
M- gas solubility;
D- diffusion constant;
t- time since the beginning of the absorption;
a- radius of the cylinder;
=h/(a2), h- height of the cylinder;
qn- positive non-zero solutions of the
equationqnJ0(qn)+2J1(qn)=0
Ice cylinders degassing (d = 9mm; h =
50 mm), saturated by hydrogen at a
pressure of 300 bar
1E-3
1000
2000
3000 4000 5000
t(s)
1,0
H2
0,8
Degassing dynamics for the
glacier ice same as for the ice
from an tap water
He
0,6
0,4
Sealed container
0,2
0,0
0 2
24
48
Time (H)
72
[1] J. Crank, The mathematics of diffusion, Oxford University press, 69-89 (1975)
[2] K.Satoh, T. Uchida, T. Hondoh, S. Mae, Proc. NIPR Symp. Polar Meteorol. Glaciol. 10, 73-81 (1996)
The experimental equipment
2
8
5
3
6
5
4
1
2
6
8
1
1
3
1) container for ice;
2) container lid;
3) sampling vessel;
4) vacuum pump;
5) vacuum valve;
6) pressure sensor;
7) temperature sensor;
8) measuring with the data acquisition module;
9) vacuum fittings
Technical problems
Vaporization in a sealed container
The surface of the core contaminated with drilling fluid (70-80% kerosene 20-30% Freon)!
Gas source
The saturation vapor pressure
(mbar) at T = -20 0C
Time of pressure
increasing to
saturation * (h)
Evaporation jars with 10 ml of
matter after 15 min. pumping *
Published
Measured
Ice
1.025
-
-
almost no vaporized
Kerosene
10
9.51
2
almost no vaporized
Freon
500
-
1.5**
vaporized completely
*- used pump was unproductive with Pmin = 2-3 mbar
**- interpolation of degassing dynamics data where freon fully turned into vapour
Leakage and the temperature dependence of the pressure sensor
Pressure (mbar)
6,5
Temperature
Pressure w/o
5,5 T correction
Pressure with
5,0
T correction
-12
4,5
-20
4,0
-22
6,0
-14
-16
-18
-24
3,5
0
24
48
Time (H)
72
-26
Temperanure (oC)
Gassing in a sealed container with
a core from storage
Leakage occurs due to loss of elasticity of Viton seals at a
temperature below -100C
Temperature correction of pressure sensor registration::
PCOR=PMEAS+ (TMEAS- TAVER)*СTEMP
PMEAS и TMEAS- measured values ​of pressure and temperature;
TAVER - the average temperature in the measurement cycle;
СTEMP – factor, picked by minimizing such bumps and dips in the
pressure curve such correlating with extremes of temperature
curve
Sampling:
dynamics of degassing
The pressure drop due to the
opening of the sampler
Degassing of ice core from borehole 5G-3
extracted from a depth of 3457 m
The pressure
rise in the free
volume of the
sealed
container
Pressure (mbar)
60
50
40
30
20
Pressure
Mathematical model of ice cylinder
10
0
0
12
24
36
48
60
Time (H)
Degassing of ice core from borehole 5G-3
extracted from a depth of 3484 m
Is it
hydrogen
100
Pressure (mbar)
80
Data was approximated by using model of
desorption from ice cylinder with D=110 mm
H=1000 mm. Diffusion coefficient for hydrogen in
ice D= 2*10-8 m2/sec (found in [1]) was used.
Fitting parameter is saturation pressure PS.
The gas pressure in the ice PGASICE normalization of
the value found for PS:PGASICE=PS*V FS/VICE
VFS- free volume , VICE- ice volume
Found values:
PGASICE(3457)=6 mbar; СGASICE(3457)=271mкМ
PGASICE(3484)=6.2 mbar; СGASICE(3484)=280mкМ
???
60
СH2ICE(М)
40
10-10 10-9 10-8 10-7 10-6 10-5
20
Pressure
Mathematical model of ice cylinder
0
0
10
20
30
40
Time (H)
50
60
Hydrogen pressure of
atmospheric ice
[1] H.L. Strauss, Z. Chen, C.K. Loong, J. Chem. Phys. 101, 7177 (1994)
10-4 10-3
10-2 10-1
1
Hydrogen pressure from ice
which placed in a gas
environment with PH2 = 350bar
Mass spectrometric analysis of the gas composition of samples:
oxygen penetration and nitrogen from kerosene into the ice cores
N O
H2O
N2 O2
HO
I
_prob (arb.un.)
6
5
4
H2
H
3
2
freon B141
1
0
10
20
30
40
50 60
M/e
70
80
90 100
The content of N2 and O2
In the air: 78% N2; 21% O2
In degassing core samples (from the mass spectrum): 70% N2;29% O2
The gases from the air, dissolved in kerosene: 68%N2; 30% O2
(solubility of oxygen in the kerosene is more than the solubility of nitrogen)
The main content of the gas from the cores is air which dissolved in kerosene
Mass spectrometric analysis of the gas composition of samples:
hydrogen content in the samples, the problem of water
Measurements of samples were alternated with measurements of local air.
Samples:
1) The reference gas mixture containing 0.5% hydrogen
2) Air sampled at Vostok
3) The gas from the core of 3450 m
4) The gas from the core of 3457 m
Samples:
5) The gas from the core of 3484 m
6) The gas from the core from storage
7) The gas from the core of 3400 m
8) The gas, which contained a vapour of kerosene
The intensity of the H2 line
2
7
4
1
3
5
6
The intensity of the H2O line
2
8
60
Air
Samples
50
45
40
6
8
Air
Samples
1000
I(arb.un.)
I(arb.un.)
55
5
3
1200
7
4
1
800
600
35
0
2000
4000 6000
Time (sec)
8000 10000
0
2000
4000
6000
8000 10000
Time (sec)
H2 line intensity decreases with time as well as the intensity of the line
of H2O: strong correlation!!!
Mass spectrometric analysis of the gas composition of samples:
hydrogen content in the samples, the problem of freon
Samples:
5) The gas from the core of 3484 m
6) The gas from the core from storage
7) The gas from the core of 3400 m
8) The gas, which contained a vapour of kerosene
2
1
3
I_Line81 (arb.un.)
If we subtract the intensity of the
"contribution of water" from the
hydrogen peak, and then normalized
to the intensity of the resulting model,
we get the hydrogen content in the
sample. Putting aside the same graph
intensity 81st line becomes clear that
most of the hydrogen correlated
with Freon
7
4
5
6
8
160
0,544
140
0,476
120
0,408
100
0,340
80
0,272
60
0,204
40
0,136
20
0,068
0
0
2000
H2 (%)
Samples:
1) The reference gas mixture containing 0.5% hydrogen
2) Air sampled at Vostok
3) The gas from the core of 3450 m
4) The gas from the core of 3457 m
0,000
4000 6000 8000 10000
Time (sec)
Volumetrically contaminated
sample
If hydrogen is formed during the ionization of Freon in the mass spectrometer???
Mass spectrometric analysis of the gas composition of samples:
hydrogen content in the samples frozen in liquid nitrogen
Decrease in the intensity of the peaks in the mass spectrum during the freezing:
After freezing the hydrogen
content is still correlated with
the content of Freon. The
measured hydrogen is not a
splinter of ionization of freon.
Local air
Gas from 3400m core
dIH2O
14.7
27
dIM81
-
>2580
160
1
2
3
4
5
25
140
24
120
23
100
22
80
21
60
20
19
40
18
20
17
0
-20
16
H2 line of frozen samples
Samples:
1) The gas from the core of 3450 m
2) The gas from the core of 3457 m
3) The gas from the core of 3484 m
4) The gas from the core of 3400 m
5) The gas from the core from storage
Decrease of intensities (times)
Line 81 before freezing
After freezing the samples, their spectra
have turned out very "clean" - not visible
spectral lines of freon; greatly weakened
spectral lines of water.
115 120 125 130 135 140 145 150 155 160 165 170
Time (min.)
Presence of Freon contamination is correlated with a hydrogen concentration in ice
cores. In order to reduce hydrogen content to natural level, it is necessary to clean
cores from 99.9% Freon.
Conclusions
-Nondestructive technique of sampling of light gases from ice cores, was
developed.
-Developed technique was first applied during the 58th RAE to ice cores from the
depth interval 3400-3484 meters.
-As a result of testing the developed technique a number of technical deficiencies
in its implementation were identified.
-Analysis of the samples detects contamination of ice cores by vapor of freon
B141 . The concentration of molecular hydrogen in the studied cores of ice are
correlated with the concentrations of vapor of freon. The maximum concentration
of 0.2 volume percent of hydrogen is observed in ice core of quick frozen lake
water from a depth of 3400 meters (volumetrically contaminated ice core).
-For a further research is necessary to use only Glacier ice cores and provides a
procedure for cleaning the surface and near-surface layer of ice cores. Contents
of components of the drilling fluid must reduced to a level of less than 0.1% of the
concentration which observed in cores investigated in this work.
Acknowledgements
Dmitriev R.P.
Efimchenko V.S.
Antonov А.S.
Еkaykin А.
(PNPI)
(ISSP)
(ISSP)
(AARI)