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Chetverikov Yu . О. 1

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

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Chetverikov Yu . О. 1

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  1. 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 ChetverikovYu. О.1 EzhovV.F.1, LipenkovV.Ya.2, KlyamkinS.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 1PNPI, St. Petersburg 2AARI, St. Petersburg 3MSU, Moscow 4 IPTI, St. Petersburg 5CFTI «ANALYTIC» St. Peterburg

  2. 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 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] Synthesis of hydrogenobacter thermophilusbacteria: ** 4H2+CO2→CH4+2H2O 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)

  3. 3535 3770 СHe(lake) 3435 СH2(lake) 3270 H(м) 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] DHe=10-9 m2/sec [2] LPEN(DH2;t=40тыс.лет)=400 m LPEN(DHe;t=40тыс.лет)=93m 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 [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)

  4. * * * * 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 3235 Prospective ice-bound space of hydrogen-oxidizingbacteria СH2(lake) H(м) Center of gas trail Depth of drilling at this year The source of gas close to the dome of subglacial island 3608 3770 СHe(lake) 3521 3208 СH2(lake) H(м)

  5. Dynamics of degassing and method of sampling The model of gas adsorption from an cylinder[1,2]: Ice cylindersdegassing (d = 9mm; h = 50 mm), saturated by hydrogen at a pressure of 300 bar Sampler 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 core Model of degassing of ice cylinder with dimension of d = 100 mm, h = 1000 mm, previously saturated with a gas Degassing dynamics for the glacier ice same as for the ice from an tap water Sealed container [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)

  6. 5 2 6 1 3 1 8 3 6 5 4 2 8 1 The experimental equipment 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

  7. Technical problems Vaporization in a sealed container The surface of the core contaminated with drilling fluid (70-80% kerosene 20-30% Freon)! *- 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 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 minimizingsuch bumps and dips in the pressure curve such correlating with extremes of temperature curve

  8. 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 Data was approximated by using model of desorption from ice cylinder with D=110 mmH=1000mm. 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- icevolume Found values: PGASICE(3457)=6 mbar; СGASICE(3457)=271mкМ PGASICE(3484)=6.2 mbar; СGASICE(3484)=280mкМ Degassing of ice core from borehole 5G-3 extracted from a depth of 3484 m Is it hydrogen ??? СH2ICE(М) 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 10-10 10-9 10-8 Hydrogen pressure from ice which placed in a gas environment with PH2 = 350bar Hydrogen pressure of atmospheric ice [1] H.L. Strauss, Z. Chen, C.K. Loong, J. Chem. Phys. 101, 7177 (1994)

  9. Mass spectrometric analysis of the gas composition of samples: oxygen penetration and nitrogen from kerosene into the ice cores H2O HO N O N2 O2 H2 H freon B141 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

  10. The intensity of the H2 line 2 7 4 8 1 2 7 4 6 8 5 1 3 6 5 3 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 H2O line H2 line intensity decreases with time as well as the intensity of the line of H2O: strong correlation!!!

  11. 2 7 4 8 1 6 5 3 H2 (%) Mass spectrometric analysis of the gas composition of samples: hydrogen content in the samples, the problem of freon 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 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 Volumetrically contaminated sample If hydrogen is formed during the ionization of Freon in the mass spectrometer???

  12. 2 4 1 3 5 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 samples, their spectra have turned out very "clean" - not visible spectral lines of freon; greatly weakened spectral lines of water. 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 After freezing the hydrogen content is still correlated with the content of Freon. The measured hydrogen is not a splinter of ionization of freon. 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.

  13. Conclusions • Nondestructive technique of sampling of light gasesfrom 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.

  14. Acknowledgements DmitrievR.P. (PNPI) EfimchenkoV.S. (ISSP) Antonov А.S. (ISSP) Еkaykin А. (AARI)

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