Geologic methane emissions from the Daginsky thermo-mineral springs in the northeast of Sakhalin Island: 2024 expedition and remote sensing data

Abstract

The paper deals with the urgent problem of gas-geochemical parameters in the seas and shelf transit zones based on a comparison of field studies and remote sensing data. The results of complex gas-geochemical studies of the Daginsky gas-hydrothermal system are presented, as well as an assessment of methane emissions from the studied area. The Daginsky gas-hydrothermal system is located on the northeastern coast of Sakhalin Island, and is a unique object due to a combination of a number of factors: from zonality due to the proximity of the Okhotsk Sea and the geological structure, to the interaction of deep and surface processes manifested in the presence of biogenic and thermogenic methane, as well as mantle helium. Tectonic faults and oil and gas bearing structures of the northeastern shelf of Sakhalin, which determine the direction of natural gas flows and facilitate its migration to the surface, make a sig-nificant contribution to the gas appearance of thermal springs. The main gas is methane up to 90%, homo-logues of methane up to and including pentane have been established, and isolated high concentrations of helium and hydrogen, both dissolved and in the free gas of bubbles, have also been noted. The con-ducted isotope studies allow to speak about the complex genesis of the gas. δ¹³ C isotopic composition, ranging from −49.4‰ to −60.2‰ shows the dominance of biogenic methane with an admixture of ther-mogenic component. This is also confirmed by the presence of a fraction of mantle helium. The flow of methane into the atmosphere from the Daginsky area is 963757.5 mol/(km² day), or about 15.4 t/(km²-year), which indicates the importance of this region for the regional and global carbon cycle. The dynam-ics of methane emissions can vary depending on various factors, such as seasonal fluctuations and geological activity, which further complicates the understanding of processes in the region.

Keywords

Methane emission / Helium / Geothermal systems / Sakhalin Island / Cold seeps

Data Availability Statement

Data will be made available on request.

CRediT authorship contribution statement

Nadezhda Syrbu: Writing - original draft, Funding acquisition, Formal analysis, Conceptualization. Andrei Kholmogorov: Visual-ization, Methodology, Conceptualization. Aleksey Legkodimov: Writing - review & editing, Data curation. Igor Stepochkin: Methodology. Rafael Zharkov: Validation, Data curation. Anatoly Salyuk: Methodology. Vyacheslav Kantalin: Methodology.

Declaration of competing interest

The authors declare that they have no known competing finan-cial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This research was funded by a grant Russian Science Foundation (No. 23-77-10038, https://rscf.ru/project/23-77-10038/) and partly within the framework of the state task of the POI FEB RAS (No. 124022100078-7).

References

[1] Aitken, C.M., Jones, D.M., Larter, S.R., 2004. Anaerobic hydrocarbon biodegradation in deep subsurface oil reservoirs. Nature 431, 291-294. https://doi.org/10.1038/nature02922.

[2] Anderson, D.L., 2000. The statistics and distribution of helium in the mantle. Int. Geol. Rev. 42, 289-311. https://doi.org/10.1080/00206810009465084.

[3] Anthony, K.M.W., Anthony, P., Grosse, G., Chanton, J., 2012. Geologic methane seeps along boundaries of Arctic permafrost thaw and melting glaciers. Nat. Geosci. 5, 419-426. https://doi.org/10.1038/ngeo1480.

[4] Ballentine, C.J., Burnard, P.G., 2022. Production, release and transport of noble gases in the continental crust. Rev. Mineral. Geochem. 47 (1), 481-538. https://doi.org/10.2138/rmg.2002.47.12.

[5] Bange, H.W., Bartell, U.H., Rapsomanikis, S., Andreae, M.O., 1994. Methane in the Baltic and North Seas and a reassessment of the marine emission of methane. Glob. Biogeochem. Cycles. 8 (4), 465-480. https://doi.org/10.1029/94GB02181.

[6] Buchwitz, M., Schneising, O., Reuter, M., Heymann, J., Krautwurst, S., Bovensmann, H., Burrows, J.P., Boesch, H., Parker, R., Somkuti, P., Detmers, R., Hasekamp, O., Aben, I., Butz, A., Frankenberg, C., Turner, A.J., 2017. Satellite-derived methane hotspot emission estimates using a fast data-driven method. Atmos. Chem. Phys. 17, 5751-5774. https://doi.org/10.5194/ACP-2016-755.

[7] Bulgakov, R.F., Ivashchenko, A.I., Kim, Ch.U., Sergeev, K.F, Strel’tsov, M.I., Kozhurin, A.I., Besstrashnov, V.M., Strom, A.L., Suzuki, Y., Tsutsumi, H., Watanabe, M., Ueki, T., Shimamoto, T., Okumura, K., Goto, H., Kariya, Y., 2002. Active faults in Northeastern Sakhalin. Geotect. 36(3), 227-246. https://doi.org/10.5800/GT-2017-8-1-0237.

[8] Capasso, G., Inguaggiato, S., 1998. A simple method for the determination of dissolved gases in natural waters: An application to thermal waters from Vulcano Island. Appl. Geochem. 13 (5), 631-642. https://doi.org/10.1016/s0883-2927(97)00109-1

[9] Chelnokov, G.A., Bragin, I.V., Kharitonova, N.A., 2018. Geochemistry mineral waters and gases of the Sakhalin Island (Far East of Russia). J. Hydrol. 559, 942-953. https://doi.org/10.1016/j.jhydrol.2018.02.049.

[10] Chen, J., Liu, K., Dong, Q., Wang, H., Luo, B., Dai, X., 2021. Research status of helium resources in natural gas and prospects of helium resources in China. Nat. Gas Geosci. 32, 1436-1449. https://doi.org/10.3390/en17071530.

[11] Chuang, P.-C., Yang, T., Hong, W.-L., Lin, S., Sun, C.-L., Lin, A., Wang, Y., Chung, S.-H., 2010. Estimation of methane flux offshore SW Taiwan and the influence of tectonics on gas hydrate accumulation. Geofluids 10, 497-510. https://doi.org/10.1111/j.1468-8123.2010.00313.x.

[12] EPA, 2010. Methane and Nitrous Oxide Emissions from Natural Sources. Environmental Protection Agency Office of Atmospheric Programs, Washington, DC, USA, pp. 1-194.

[13] Ershov, V.V., 2017. On the problem of variability in the chemical composition of mud-volcanic waters: evidence from the Yuzhno-Sakhalinsk mud volcano. Russ. J. Pac. Geol. 111, 73-80. https://doi.org/10.1134/S1819714017010031.

[14] Ershov, V.V., Nikitenko, O.A., Zharkov, R.V., 2023. Thermomineral waters on the Daginsky field (Sakhalin Island): physical-chemical characteristics and formation conditions. Bull. Tomsk Polytech. Univ. Geo Assets Eng. 334, 104- 118 https://doi.org/10.18799/24131830/2023/3/3874.

[15] Etiope, G., Papatheodorou, G., Christodoulou, D., Geraga, M., Favali, P., 2006. The geological links of the ancient Delphic Oracle (Greece): a reappraisal of natural gas occurrence and origin. Geology 34 (10), 821-824. https://doi.org/10.1130/G22824.1.

[16] Etiope, G., 2009. Mud volcanoes and microseepage: the forgotten geophysical components of atmospheric methane budget. Ann. Geophys. 48 (1), 1-7. https://doi.org/10.4401/ag-3175.

[17] Etiope, G., Baciu, C., Caracausi, A., Italiano, F., Cosma, C., 2004. Gas flux to the atmosphere from mud volcanoes in Eastern Romania. Terra Nova 16 (4), 179-184. https://doi.org/10.1111/j.1365-3121.2004.00542.x.

[18] Etiope, G., Fridriksson, T., Italiano, F., Winwarter, W., Theloke, J., 2007. Natural emissions of methane from geothermal and volcanic sources in Europe. J. Volcanol. Geotherm. Res. 165, 76-86. https://doi.org/10.1016/j.jvolgeores.2007.04.014.

[19] Etiope, G., Klusman, R.W., 2022. Geologic emissions of methane to the atmosphere. Chemosphere 49 (8), 777-789. https://doi.org/10.1016/S0045-6535(02)00380-6

[20] Etiope, G., Lassey, K.R., Klusman, R., Boschi, E., 2008. Re-appraisal of the fossil methane budget and related emission from geologic sources. Geophys. Res. Lett. 35, 1-5. https://doi.org/10.1029/2008GL033623.

[21] Etiope, G., Milkov, A.V., 2004. A new estimate of global methane flux from onshore and shallow submarine mud volcanoes to the atmosphere. Environ. Geol. 46 (8), 997-1002. https://doi.org/10.1007/s00254-004-1085-1.

[22] Ferretti, D.F., Miller, J.B., White, J.W.C., Etheridge, D.M., Lassey, K.R., Lowe, D.C., Meure, C.M.M., Dreier, M.F., Trudinger, C.M., van Ommen, T.D., Langenfelds, R.L., 2005. Unexpected changes to the global methane budget over the past 2000 years. Science309(5741),1714-1717.https://doi.org/10.1126/science.1115193.

[23] Geology of USSR, v. XXXIII., 1970. Sakhalin Island, Geological Description. In: Vereshchagin, V.N., Kovtunovich, Yu.M., Sidorenko, A.V. (Eds.), Geology of USSR, v. XXXIII., Nedra Publ., Moscow, pp. 1-432 (in Russian).

[24] Gladenkov, Y.B., Bazhenova, O.K., Grechin, V.I., Margulis, L.S., Salnikov, B.A., 2002. The Cenozoic of Sakhalin and Its Oil and Gas Potential. GEOS, Moscow, pp. 1- 225 (in Russian).

[25] Harder, S.L., Shindell, D.T., Schmidt, G.A., Brook, E.J., 2007. A global climate model study of CH 4 emissions during the Holocene and Glacial-Interglacial Transitions constrained by ice core data. Glob. Biogeochem. Cycles. 21 (1), GB1011. https://doi.org/10.1029/2005GB002680.

[26] Hayhoe, K., 2002. Atmospheric methane and global change. Earth-Sci. Rev. 57, 177-210. https://doi.org/10.1016/S0012-8252(01)00062-9

[27] Hornafius, J.S., Quigley, D., Luyendyk, B.P., 1999. The world’s most spectacular marine hydrocarbon seeps (Coal Oil Point, Santa Barbara Channel, California): Quantification of emissions. J. Geophys. Res. 104, 20703-20711.

[28] Houweling, S., Kaminski, T., Dentener, F., Lelieveld, J., Heimann, M., 1999. Inverse modeling of methane sources and sinks using the adjoint of a global transport model. J. Geophys. Res. Atmos. 104 (D21), 26137-26160. https://doi.org/10.1029/1999JD900428.

[29] IPCC, 1996. Climate Change 1994. In: Houghton, J.T., Houghton, J.T., Meiro Filho, L. G., Callander, B.A., Harris, N., Kattenberg, A., Maskell, K. (Eds.), Intergovernmental Panel on Climate Change. Cambridge Univ. Press, Cambridge, pp. 1-86.

[30] Judd, A.G., Hovland, M., Dimitrov, L.I., Gil, S.G., Jukes, V., 2002. The geological methane budget at continental margins and its influence on climate change. Geofluids 2 (2), 109-126. https://doi.org/10.1046/j.1468-8123.2002.00027.x.

[31] Kharakhinov, V.V., 2010. Oil and Gas Geology of the Sakhalin Region. Scientific World, Moscow, pp. 1-276 (in Russian).

[32] Kirschke, S., Bousquet, P., Ciais, P., Saunois, M., Canadell, J., Dlugokencky, E., Bergamaschi, P., Bergmann, D., Blake, D., Bruhwiler, L., Cameron-Smith, P., Castaldi, S., Chevallier, F., Feng, L., Fraser, A., Heimann, M., Hodson, E., Houweling, S., Josse, B., Zeng, G., 2013. Three decades of global methane sources and sinks. Nat. Geosci. 6, 813-823. https://doi.org/10.1038/NGEO1955.

[33] Klusman, R., Leopold, M., LeRoy, M., 2000. Seasonal variation in methane fluxes from sedimentary basins to the atmosphere: results from chamber measurements and modeling of transport from deep sources. J. Geophys. Res. Atms. 105 (D20), 24661-24670. https://doi.org/10.1029/2000JD900407.

[34] Konovalov, A.V., Stepnov, A.A., Gavrilov, A.V., Manaychev, K.A., Sychov, A.S., Klachkov, V.A., Saburov, M.S., 2016. Regional seismicity behavior in the Northern Sakhalin in connection to offshore oil and gas fields production. Istoriya Nauki i Tekhniki (history of Science and Engineering) 6, 63-71 (in Russian).

[35] Kvenvolden, K., Lorenesonm, T.D., Reeburgh, W.S., 2001. Attention turns to naturally occurring methane seepage. Eos Trans. AGU 82 (40), 457-458. https://doi.org/10.1029/01EO00275.

[36] Lammers, S., Suess, E., Mansurov, M.N., Anikiev, V.V., 1995. Variations of atmospheric methane supply from the Sea of Okhotsk induced by the seasonal ice cover. Global Biogeochem. Cy. 9 (3), 351-358. https://doi.org/10.1029/95gb01144.

[37] Lavrushin, V.Y., Polyak, B.G., Prasolov, R.M., Kamenskii, I.L., 1996. Sources of material in mud volcano products. Lithol. Mineral Resour. 316, 557-578.

[38] Lupton, J.E., 1983. Terrestrial inerts gases: Isotope tracer studies and clues to primordial components in the mantle. Annu. Rev. Earth Planet. Sci. 11, 371-414. https://doi.org/10.1146/annurev.ea.11.050183.002103.

[39] Mamyrin, B.A., Anufriyev, G.S., Kamenskiy, I.L., Tolstikhin, I.N., 1970. Determination of the isotopic composition of atmospheric helium. Geochem. Int. 7, 498-505.

[40] Mamyrin, B. A., Tolstikhin, I. N., 1984. Helium Isotopes in Nature. Elsevier, New York, pp. 1-97.

[41] Mazzini, A., Sciarra, A., Etiope, G., Sadavarte, P., Houweling, S., Pandey, S., Husein, A., 2021. Relevant methane emission to the atmosphere from a geological gas manifestation. Sci. Rep. 11, 4138. https://doi.org/10.1038/s41598-021-83369-9.

[42] McCrory, P., Constantz, J., Hunt, A., Blair, J., 2016. Helium as a tracer for fluids released from Juan de Fuca lithosphere beneath the Cascadia forearc. Geochem. Geophys. Geosyst. 17, 2434-2449. https://doi.org/10.1002/2015GC006198.

[43] Melnikov, A.Y., Ilyev, O.A., 1989. New manifestations of mud volcanism on Sakhalin. Russian J. of Pacific Geology 3, 42-48 (in Russian).

[44] Milkov, A.V., Sassen, R., Apanasovich, T.V., Dadashev, F.G., 2003. Global gas flux from mud volcanoes: a significant source of fossil methane in the atmosphere and the ocean. Geophys. Res. Lett. 30 (2), 1037. https://doi.org/10.1029/2002GL016358.

[45] Mishukova, G.I., Shakirov, R.B., Obzhirov, A.I., 2017. Methane fluxes on the water- atmosphere boundary in the sea of Okhotsk. Dokl. Earth Sci. 475 (2), 963-967. https://doi.org/10.1134/S1028334X17080256.

[46] Mishukova, G.I., Mishukov, V.F., Obzhirov, A.I., Pestrikova, N.L., Vereshchagina, O.F., 2015. Peculiarities of the distribution of methane concentration and methane fluxes at the water-air interface in the Tatar Strait of the Sea of Japan. Russ. Meteorol.Hydrol. 40(6),427-433.https://doi.org/10.3103/S1068373915060096.

[47] Nikitenko, O., Ershov, V., Rafael, Z., Ustyugov, G.,2022. Dynamics of the physicochemical characteristics of the thermomineral waters of the Daginsky field (before the reconstruction of the springs in 2019-2020). Geo. Trans. Zones 6 (3), 183-194 https://doi.org/10.30730/gtrz.2022.6.3.183-194

[48] Obzhirov, A.I., Pestrikova, N.L., Mishukova, G.I., Mishukov, V.F., Okulov, A.K., 2016. Distribution of methane content and methane fluxes in the Sea of Japan, Sea of Okhotsk, and near-Kuril Pacific. Russ. Meteorol. Hydrol. 41, 205-212. https://doi.org/10.3103/S1068373916030067.

[49] Oxburgh, E.R., O’Nions, R.K., Hill, R.I., 1986. Helium isotopes in sedimentary basins. Nature 324, 632-635. https://doi.org/10.1038/324632a0.

[50] Ozima, M., Podosek, F., 2002. Noble Gas Geochemistry. Cambridge University Press, New York, pp. 1-286.

[51] Park, K.-A., Kim, K., Cornillon, P.C., Chung, J.Y., 2006. Relationship between satellite-observed cold water along the Primorye coast and sea ice in the East Sea (the Sea of Japan). Geophys. Res. Lett. 33, L10602. https://doi.org/10.1029/2005GL025611.

[52] Pavlova, V.Y., Zharkov, R.V., 2018. GPR results on the territory of the Daginsky hydrothermal system (Sakhalin Island). Geo. Trans. Zones 2 (4), 323-331 https://doi.org/10.30730/2541-8912.2018.2.4.323-331

[53] Pavlova, V.Y., Zharkov, R.V., Delemen, I.F., 2019. 3-D structure of the discharging zone of the Daginsky hydrothermal system (Sakhalin Island) according to the ground penetrating radar method and well logs. IOP Conf. Ser.: Earth Environ. Sci. 324 (1), 012026. https://doi.org/10.1088/1755-1315/324/1/012026.

[54] Porcelli, D., Ballentine, C.J., Wieler, R., 2002. An overview of noble gas geochemistry and cosmochemistry. Rev. Mineral. Geochem. 47, 1-19. https://doi.org/10.1515/9781501509056-003.

[55] Poreda, R.J., Jeffrey, A.W.A., Kaplan, I.R., Craig, H., 1988. Magmatic helium in subduction-zone natural gases. Chem. Geol. 71, 199-210. https://doi.org/10.1016/0009-2541(88)90115-5

[56] Qin, S., Xu, D., Li, J., Zhou, Z., 2002. Genetic types, distribution patterns and enrichment mechanisms of helium in China’s petroliferous basins. Front. Earth Sci. 10, 675109. https://doi.org/10.3389/feart.2022.675109.

[57] Reay, D.S., Smith, P., Christensen, T., James, R.H., Clark, H., 2018. Methane and global environmental change. Annu. Rev. Environ. Resour. 43 (1), 165-192. https://doi.org/10.1146/annurev-environ-102017-030154.

[58] Rosentreter, J.A., Borges, A.V., Deemer, B.R., Holgerson, M.A., Liu, S., Song, C., Melack, J.M., Raymond, P.A., Duarte, C.M., Allen, G.H., Olefeldt, D., Poulter, B.I., Battin, T.I., Eyre, B.D., 2021. Half of global methane emissions come from highly variable aquatic ecosystem sources. Nat. Geosci. 14, 225-230. https://doi.org/10.1038/s41561-021-00715-2.

[59] Sano, Y., Nakajima, J., 2008. Geographical distribution of 3 He/ 4 He ratios and seismic tomography in Japan. Geochem. J. 42 (1), 51-60. https://doi.org/10.2343/geochemj.42.51.

[60] Shakirov, R.B., Syrbu, N.S., Obzhirov, A.I., 2012. Isotope and gas-geochemical features of methane and carbon dioxide distribution on Sakhalin Island and adjacent shelf of the Okhotsk Sea. Bull. KRAESC Earth Sci. 2 (20), 100-113.

[61] Shakirov, R.B., Valitov, M.G., Obzhirov, A.I., Mishukov, V.F., Yatsuk, A.V., Syrbu, N.S., Mishukova, O.V., 2019. Methane anomalies, its flux on the sea-atmosphere interface and their relations to the geological structure of the South-Tatar sedimentary basin (Tatar Strait, the Sea of Japan). Mar. Geophys. Res. 40, 581-600. https://doi.org/10.1007/s11001-019-09389-3.

[62] Shakirov, R., Mishukova, O., 2019. The spatial distribution of the methane fluxes on the water-atmosphere boundary in the Sea of Okhotsk. Geo. Trans. Zones 3 (1), 107-123 https://doi.org/10.30730/2541-8912.2019.3.1.107-123

[63] Shakirov, R., Obzhirov, A., Suess, E., Salyuk, A., Nicole, B., 2004. Mud volcanoes and gas vents in the Okhotsk Sea area. Geo-Mar. Lett. 24, 140-149. https://doi.org/10.1007/s00367-004-0177-y

[64] Shakirov, R.B., Syrbu, N.S., Obzhirov, A.I., 2016. Distribution of helium and hydrogen in sediments and water on the Sakhalin slope. Lithol. Mineral Resour. 51, 61-73. https://doi.org/10.1134/S0024490216010065.

[65] Snyder, G.T., Yatsuk, A., Takahata, N., Shakirov, R., Tomaru, H., Tanaka, K., Obzhirov, A., Salomatin, A., Aoki, S., Khazanova, E., Maryina, E., Sano, Y., Matsumoto, R., 2022. Ocean dynamics and methane plume activity in Tatar Strait, Far Eastern Federal District, Russia as revealed by seawater chemistry, hydroacoustics, and noble gas isotopes. Front. Earth Sci. 10, 825679. https://doi.org/10.3389/ feart.2022.825679.

[66] Sokolova, N.L., Telegin, Y.A., Venikova, A.L., Obzhirov, A.I., 2022. Gas geochemical studies of the Dagi gas-hydrothermal system on the Sakhalin east coast. Russ. J. Pac. Geol. 16, 503-509. https://doi.org/10.1134/S1819714022050104.

[67] Sorochinskaya, A.V., Shakirov, R.B., Venikova, A.L., Pestrikova, N.L., 2015. Elements-admixtures in the modern mud breccias on the mud volcanoes in Sakhalin Island. Bull. KRAESC Earth Sci. 1, 231-242.

[68] Stolper, D.A., Lawson, M., Davis, C.L., Ferreira, A.A., Neto, S.E.V., Ellis, G.S., Lewan, M. D., Martini, A.M., Tang, Y., Schoell, M., Sessions, A.L., Eiler, J.M., 2014. Gas formation. formation temperatures of thermogenic and biogenic methane. Science 344 (6191), 1500-1503. https://doi.org/10.1126/science.1254509.

[69] Stra˛poc, D., 2017. Biogenic methane. In: White, W. (Eds), Encyclopedia of Geochemistry. Encyclopedia of Earth Sciences Series. Springer, Cham, pp.1-9. https://doi.org/10.1007/978-3-319-39193-9_166-1.

[70] Syrbu, N., Kholmogorov, A., Stepochkin, I., Lobanov, V., Shkorba, S., 2024. Formation of abnormal gas-geochemical fields and dissolved gases transport at the shallow northeastern shelf of Sakhalin Island in warm season: Expedition data and remote sensing. Water 16, 1434. https://doi.org/10.3390/w16101434.

[71] Syrbu, N.S., Snyder, G.T., Shakirov, R.B., Kholmogorov, A.O., Zharkov, R.V., Tsunogai, U., 2022. Geochemical distribution of helium, hydrogen, carbon dioxide, and methane in Sakhalin Island mud volcanoes, hot springs, and cold seeps. J. Volcanol. Geotherm. Res. 431, 107667. https://doi.org/10.1016/j.jvolgeores.2022.107667.

[72] Vasilenko, N., Prytkov, A., 2019. Contemporary geodynamics of the Garomal active fault (Sakhalin Island). Geodyn. Tectonophys. 10, 561-567. https://doi.org/10.5800/GT-2019-10-2-0426.

[73] Vasilenko, N.F., Prytkov, A.S., 2012. GPS-based modeling of the interaction between the lithospheric plates in Sakhalin. Russ. J. Pac. Geol. 6 (1), 35-41. https://doi.org/10.1134/s1819714012010137.

[74] Velivetskaya, T.A, Ignatev, A., Kiyashko, S., 2015. Universal method for preparation of liquid, solid and gaseous samples for determining the isotopic composition of carbon. In: Sevastyanov, V.S. (Ed.), Isotope Ratio Mass Spectrometry of Light Gas-Forming Elements. CRC Press, UK, pp. 119-134.

[75] Vereshchagina, O.F., Korovitskaya, E.V., Mishukova, G.I., 2013. Methane in water columns and sediments of the north western Sea of Japan. Deep-Sea Res. II: Top. Stud. Oceanogr. 86-87, 25-33. https://doi.org/10.1016/j.dsr2.2012.08.017.

[76] Voeikova, O.A., Nesmeyanov, S.A., Serebryakova, L.I., 2007. Neotectonics and Active Faults of Sakhalin, Nauka Publ., Moscow, p. 187 (in Russian).

[77] Wakita, H., Sano, Y., 1983. 3 He/4 He ratios in CH4-rich natural gases suggest magmatic origin. Nature 305, 792-794. https://doi.org/10.1038/305792a0.

[78] Whiticar, M.J., 1990. A geochemical perspective of natural gas and atmospheric methane. Org. Geochem. 16 (1-3), 531-547.

[79] Wiessenburg, D.A., Guinasso, N.L., 1979. Equilibrium solubility of methane, carbon dioxide, and hydrogen in water and sea water. J. Chem. Eng. Data. 4, 356-360.

[80] Wuebbles, D., Hayhoe, K., 2000. Atmospheric methane:trends and impacts. In: van Ham, J., Baede, A.P.M., Meyer, L.A., Ybema, R. (Eds.), Non-CO2 Greenhouse Gases: Scientific Understanding, Control and Implementation. Springer, Dordrecht, pp. 1-44. https://doi.org/10.1007/978-94-015-9343-4_1.

[81] Xu, Y., 1996. The mantle noble gas of natural gases. Front. Earth Sci. 3, 63-71.

[82] Xu, Y., 1997. Helium isotope distribution of natural gases and its structural setting. Front. Earth Sci. 4, 185-190.

[83] Xu, Y., Shen, P., Tao, M., Liu, W., 1997. Geochemistry on mantle-derived volatiles in natural gases from eastern China oil/gas provinces (II). Sci. China, Ser. D-Earth Sci. 40 (2), 315-321. https://doi.org/10.1007/BF02877541.

[84] Yamamoto, S., Alcauskas, J.B., Crozier, T.E., 1976. Solubility of methane in distilled water and sea water. J. Chem. Eng. Data 21, 78-80.

[85] Yoshida, O., Yoshikawa-Inoue, H., Watanabe, S., Noriki, S., Wakatsuchi, M., 2004. Methane in the western part of the Sea of Okhotsk in 1998-2000. J. Geophys. Res. Oceans 109 (9), C09S12. https://doi.org/10.1029/2003JC001910.

[86] Zavadsky, I.G., 1991. Exploration work at the Daginsky field of thermal waters in the Nogliki District: A report for 1990-1991, Sakhalingeology Publ., Yuzhno-Sakhalinsk, p. 218 (in Russian).

[87] Zharkov, R.V., 2018. Modern physicochemical features of thermomineral water of the Daginsky deposit (Sakhalin island). Monit. Sci. Tech. 4 (37), 35-40 https://doi.org/10.25714/MNT.2018.37.004.

[88] Zheng, G., Ma, X., Guo, Z., Hilton, D.R., Wang, X., Liang, S., Fan, Q., Chen, W., 2017. Gas geochemistry and methane emission from Dushanzi mud volcanoes in the southern Junggar Basin, NW China. J. Asian Earth Sci. 149, 184-190. https://doi.org/10.1016/j.jseaes.2017.08.023.

[89] Zhiltsov, A.M., 2000. The gas saturation zones in the upper part of the sedimentary cover are a direct sign of the presence of hydrocarbon deposits at depth. In: Kochergin, E.V. (Ed.), The Structure of the Earth’s Crust and Prospects for Oil and Gas Potential in the Regions of the Northwestern Edge of the Pacific Ocean. IMGG FEB RAS, Yuzhno-Sakhalinsk, 1, pp. 76-92 (in Russian).