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. Petersburg2 AARI, St. Petersburg3 MSU, Moscow4 IPTI, St. Petersburg5 CFTI «ANALYTIC» St. Peterburg

Tectonic activity of bottom of lake Vostok and light gases in the lake

Chemosynthesis of the thermal spring is the basis of life at the bottom of deep water reservoir

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; HFН2

4H2+CO2 →CH4+2H2O

Observation of thermophilic hydrogen-oxidizing 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]

Hydrogen in ice

Synthesis of hydrogenobacter thermophilus bacteria:

*

** High concentrations of hydrogen at the base of the 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

Model of a uniform distribution of the gas in the lake under the 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]DHe=10-9 m2/sec [2]

The flow of the glacier

H(м)

37703535

3270

3435

СH2(lake)

СHe(lake)

LPEN(DH2;t=40тыс.лет)=400 mLPEN(DHe;t=40тыс.лет)=93 m

Depth concentration profile in the borehole 5G

[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)

37703608

3208

3521

СH2(lake)

СHe(lake)

Alleged place of occurrencecontent and depth profile of the light gases

The source of gas close to the dome of subglacial island

Source of gas at the interface ice-water-to-shore

H(м)

37703535

3235

3448

СH2(lake)

СHe(lake)

* *

**

Prospective ice-bound space of hydrogen-oxidizing bacteria

Depth of drilling at this year

Gas trail

Center of gas trail

Dynamics of degassingand method of sampling

1000 2000 3000 4000 50001E-3

0,01

I dism

mH

g*0

.02

5*l

/11

0*s

m2

Vostok Ice 1 Empty cellUsual Ice Vostok Ice 2

t(s)

Ice cylinders degassing (d = 9mm; h = 50 mm), saturated by hydrogen at a pressure of 300 bar

0 24 48 720,0

0,2

0,4

0,6

0,8

1,0

H2

He

Par

t of

de

sorb

ed g

as (

arb.

un.

)

Time (H)2

Model of degassing of ice cylinder with dimension of d = 100 mm, h = 1000 mm, previously saturated with a gas

Sampler

Sealed container

Ice core

The model of gas adsorption from an cylinder[1,2]:

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 equationqnJ0(qn)+2J1(qn)=0

Degassing dynamics for the glacier ice same as for the ice from an tap water

[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

52

6

1

3

1

8

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

1

42

3

56

8

Technical problems

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 9.51 2 almost no vaporized

Freon 500 - 1.5** vaporized completely

Vaporization in a sealed container

The surface of the core contaminated with drilling fluid (70-80% kerosene 20-30% Freon)!

Leakage and the temperature dependence of the pressure sensor

*- used pump was unproductive with Pmin = 2-3 mbar**- interpolation of degassing dynamics data where freon fully turned into vapour

0 24 48 72-26

-24

-22

-20

-18

-16

-14

-12

3,5

4,0

4,5

5,0

5,5

6,0

6,5

Tem

pera

nure

(oC

)

Pre

ssur

e (m

bar)

Temperature

Time (H)

Pressure w/o T correction

Pressure with T correction

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

Gassing in a sealed container with a core from storage

Sampling:dynamics of degassing

Degassing of ice core from borehole 5G-3 extracted from a depth of 3457 m

0 12 24 36 48 600

10

20

30

40

50

60

Pressure Mathematical model of ice cylinder

Time (H)

Pre

ssur

e (m

bar)

0 10 20 30 40 50 600

20

40

60

80

100

Time (H)

Pre

ssur

e (m

bar)

Pressure Mathematical model of ice cylinder

The pressure drop due to the opening of the sampler

The pressure rise in the free volume of the sealed container

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 volumeFound values:

PGASICE(3457)=6 mbar; СGASICE(3457)=271mкМPGASICE(3484)=6.2 mbar; СGASICE(3484)=280mкМ

СH2ICE(М)

10-7 10-6 10-5 10-4 10-3 10-2 10-1 1

Hydrogen pressure of atmospheric ice

Hydrogen pressure from ice which placed in a gas environment with PH2 = 350bar

10-10 10-9 10-8

Is it hydrogen

???

[1] H.L. Strauss, Z. Chen, C.K. Loong, J. Chem. Phys. 101, 7177 (1994)

Degassing of ice core from borehole 5G-3 extracted from a depth of 3484 m

Mass spectrometric analysis of the gas composition of samples:oxygen penetration and nitrogen from kerosene into the ice cores

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)

10 20 30 40 50 60 70 80 90 100

0

1

2

3

4

5

6

I_

pro

b (a

rb

.u

n.)

M/e

O2N2H2OHO

N O

freon B141

H2

H

The content of N2 and O2

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

H2 line intensity decreases with time as well as the intensity of the line of H2O: strong correlation!!!

Measurements of samples were alternated with measurements of local air.Samples:1) The reference gas mixture containing 0.5% hydrogen2) Air sampled at Vostok3) The gas from the core of 3450 m4) The gas from the core of 3457 m

Samples:5) The gas from the core of 3484 m6) The gas from the core from storage7) The gas from the core of 3400 m8) The gas, which contained a vapour of kerosene

The intensity of the H2 line

0 2000 4000 6000 8000 10000

35

40

45

50

55

60

I(ar

b.un

.)

Time (sec)

Air Samples

8 71

2

3

4

56

0 2000 4000 6000 8000 10000

600

800

1000

1200

I(ar

b.un

.)

Time (sec)

Air Samples

8 71

2

3

4

56

The intensity of the H2O line

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

Mass spectrometric analysis of the gas composition of samples:hydrogen content in the samples, the problem of freon

0 2000 4000 6000 8000 100000

20

40

60

80

100

120

140

160

0,000

0,068

0,136

0,204

0,272

0,340

0,408

0,476

0,544

Time (sec)

I_Li

ne81

(ar

b.un

.)

H2

(%)

8 71

2

3

4

56

Samples:1) The reference gas mixture containing 0.5% hydrogen2) Air sampled at Vostok3) The gas from the core of 3450 m4) The gas from the core of 3457 m

Samples:5) The gas from the core of 3484 m6) The gas from the core from storage7) The gas from the core of 3400 m8) The gas, which contained a vapour of kerosene

If hydrogen is formed during the ionization of Freon in the mass spectrometer???

Volumetrically contaminated sample

Decrease in the intensity of the peaks in the mass spectrum during the freezing:

Mass spectrometric analysis of the gas composition of samples:hydrogen content in the samples frozen in liquid nitrogen

Decrease of intensities (times)

Local air Gas from 3400m core

dIH2O 14.7 27

dIM81 - >2580

After freezing the samples, their spectra have turned out very "clean" - not visible spectral lines of freon; greatly weakened spectral lines of water.

After freezing the hydrogen content is still correlated with the content of Freon. The measured hydrogen is not a splinter of ionization of freon.

Samples:1) The gas from the core of 3450 m2) The gas from the core of 3457 m3) The gas from the core of 3484 m4) The gas from the core of 3400 m5) The gas from the core from storage

115 120 125 130 135 140 145 150 155 160 165 170-20

0

20

40

60

80

100

120

140

160

16

17

18

19

20

21

22

23

24

25

H2 li

ne

of

fro

zen

sam

ple

s

Time (min.)

Lin

e 81

bef

ore

fre

ezin

g

1 2 3 4 5

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. (PNPI)Efimchenko V.S. (ISSP)Antonov А.S. (ISSP)Еkaykin А. (AARI)