Вестник Томского государственного университета. Биология. 2019; : 6-21
Molecular and elemental composition of humic acids isolated from selected soils of the Russian Arctic
https://doi.org/10.17223/19988591/47/1Аннотация
Humic substances, isolated from selected soils of the Russian Arctic, were investigated in terms of molecular composition and stabilization rate. The degree of polar soil organic matter stabilization was assessed with the use of modern instrumental spectroscopy methods. The analysis of humic acid (HAs) preparations showed that aliphatic fragments prevail in the organic matter isolated in polar soils.
The predominance of aliphatic fragments was revealed in HAs from soils located in the coastal zone, which could be caused by regular refreshment of organic matter during sin-lithogenic process and processes of hydrogenation in HAs. Breaking of the C-C bonds and formation of chains with a high hydrogen content, which leads to the formation of aliphatic fragments in HAs, were noted. Data on the calculated atomic ratios of the elements in HAs are given and graphs show the main regularities in the formation of HAs and their properties. The integrated indicators of the molecular composition of humic acids of soils of the Russian Arctic are presented.
The paper contains 4 Tables, 4 Figures and 44 References.
Список литературы
1. Anisimov O, Arnalds O, Arnoldusen A, Bockheim J, Breuning-Madsen H, Broll G, Brown J, Desyatkin R, Goryachkin S, Jakobsen BH, Jones A, Konyushkov D, Mazhitova G, McCallum I, Montanarella L, Naumov E, Overduin PP, Nilsson S, Solbakken E, Ping CL, Ritz K, Spaargaren O, Stolbovoy V, Tarnocai C. Soil Atlas of the Northern Circumpolar Region: An initiative of the European Union to support the International Polar YearJRC European Commission. Institute for Environment. Jones A, Principal editor. Luxembourg: Publ. Office of the European Union, 144 p. doi: 10.2788/95795
2. Zubrzycki S, Kutzbach L, Pfeiffer E.-M. 2014. Permafrost-affected soils and their carbon pools with a focus on the Russian Arctic. Solid Earth. 2014;5:595-609. doi: 10.5194/se-5-595-2014
3. Schadel C, Schuur EAG, Bracho R, Elberling B, Knoblauch C, Lee H, Luo Y, Schimel DS. Terrestrial ecosystems and the carbon cycle. Global Change Biology. 1995;1:77-91. doi: 10.1111/gcb.12417
4. Schimel DS. Terrestrial ecosystems and the carbon cycle. Global Change Biology. 1995;1:77-91. doi: 10.1111/j.1365-2486.1995.tb00008.x
5. Davis TN. Permafrost: A Guide to Frozen Ground in Transition. Fairbanks, AK, U.S.A.: University of Alaska Press; 2001. 351 p.
6. Dutta K, Schuur AG, Neff JC, Zimov SA. Potential carbon release from permafrost soils of Northeastern Siberia. Global Change Biology. 2006;12:2336-2351. doi: 10.1111/j.1365-2486.2006.01259.x
7. Polyakov VI, Orlova KS, Abakumov EV. Evaluation of carbon stocks in the soils of Lena River Delta on the basis of application of “dry combustion” and Tyurin’s methods of carbon determination. Biological Communications. 2017;62:67-72. doi: 10.21638/11701/spbu03.2017.202
8. Uchaev AP, Nekrasova OA. Mobile humic substances in the forest-tundra zone podzols. BioClimLand. 2013;1:58-66.
9. Okoneshnikova MV. Current state and prediction of changes in soils of the middle Lena valley (Central Yakutia). Tomsk State University Journal of Biology. 2013;3(23):7-18. doi: 10.17223/19988591/23/1 In Russian
10. Bolter M, Blume H-P, Wetzel H. Properties, formation, classification and ecology of soils: Results from the Tundra Northwest Expedition 1999 (Nunavut and Northwest Territories, Canada). Polarforschung. 2006;73:89-101.
11. Dai XY, Ping CL, Michaelson GJ. Characterizing soil organic matter in Arctic tundra soils by different analytical approaches. Organic Geochemistry. 2002;33:407-419. doi: 10.1111/j.1365-2389.2007.00908.
12. Kutzbach L, Wagner D, Pfeiffer E-M. Effect of microrelief and vegetation on methane emission from wet polygonal tundra. Lena Delta, Northern Siberia. Biogeochemistry. 2004;69:341-362. doi: 10.1023/B:BI0G.0000031053.81520.db
13. Boike J, Kattenstroth B, Abramova K, Bornemann N, Chetverova A, Fedorova I, Frob K, Grigoriev M, Grube RM, Kutzbach L, Langer M, Minke M, Muster S, Piel K, Pfeiffer E-M, Stoof G, Westermann S, Wischnewski K, Wille C, Hubberten H-W. Baseline characteristics of climate, permafrost and land cover from new permafrost observatory in the Lena River Delta, Siberia (1998-2011). Biogeosciences. 2013;10:2105-2128. doi: 10.5194/bg-10-2105-2013
14. Kirpotin SN. Western Siberia in a changing climate. International J Environmental Studies. 2014;71(5):591-594. doi: 10.1080/00207233.2014.945695
15. Cazzolla Gatti R, Callaghan TV, Rozhkova-Timina I, Dudko A, Lim A, Vorobyev SN, Kirpotin SN, Pokrovsky OS. The role of Eurasian beaver (Castor fiber) in the storage, emission and deposition of carbon in lakes and rivers of the River Ob flood plain, western Siberia. Science of the Total Environment. 2018;644:1371-1379. doi: 10.1016/j.scitotenv.2018.07.042
16. Lodygin ED, Beznosikov VA. The molecular structure and elemental composition of humic substances from Albeluvisols. Chemistry and Ecology. 2010;26:87-95. doi: 10.1080/02757540.2010.497759
17. Ejarque E, Abakumov E. Stability and biodegradability of organic matter from Arctic soils of Western Siberia: Insights from 13C-NMR spectroscopy and elemental analysis. Solid Earth. 2016;7:153-165. doi: 10.5194/se-7-153-2016
18. Lodygin E, Beznosikov V, Abakumov E. Humic substances elemental composition of selected taiga and tundra soils from Russian European North-East. Polish Polar Research. 2017;38:125-147. doi: 10.1515/popore-2017-0007
19. Lupachev A, Abakumov E, Gubin S. The influence of cryogenic mass exchange on the composition and stabilization rate of soil organic matter in cryosols of the Kolyma Lowland (North Yakutia. Russia). Geosciences. 2017;7:24. doi: 10.3390/geosciences7020024
20. Zharinova NY, Yamskih AA. Humus characteristics of alluvial dark-humus soils of Krasnoyarsk forest-steep. Tomsk State University Journal ofBiology. 2011;1(13):5-10. In Russian
21. Chefetz B, Salloum MJ, Deshmukh AP, Hatcher PG. Structural components of humic acids as determined by chemical modifi cations and carbon - 13 NMR, pyrolysis and thermochemolysis-gas chromatography/mass spectrometry. Soil Science Society of America Journal. 2002;66:1159-1171. doi: 10.1016/S1001-0742(08)62285-8
22. Szymanski W, Wojtun B, Stolarczyk M, Siwek J, Wascinska J. Organic carbon and nutrients (N, P) in surface soil horizons in a non-glaciated catchment, SW Spitsbergen. Polish Polar Research. 2016;37:49-66. doi: 10.1515/popore-2016-000
23. Lodygin ED, Beznosikov VA, Vasilevich RS. Molecular composition of humic substances in tundra soils (13C-NMR spectroscopic study). Eurasian Soil Science. 2014;47:400-406. doi: 10.1134/S1064229314010074
24. Chukov SN, Abakumov EV, Tomashunas VM. Characterization of humic acids isolated from Antarctic soils by 13C NMR spectroscopy. Eurasian Soil Science. 2015;48:1207-1211. doi: 10.1134/S1064229315110046
25. Glazov MV, Goryachkin SV. Changes in natural zones of the Russian Arctic. Priroda. 1997;5:32-47. In Russian
26. IUSS Working Group WRB World Reference Base for Soil Resources 2014, update 2015. International Soil Classification System for Naming Soils and Creating Legends for Soil Maps. World Soil Resources Reports No. 106. Rome: FAO; 2015. 192 p.
27. Swift RS. Organic matter characterization. In: Soil Science Society of America Book Series. No 5. Methods of soil analysis. Pt 3. Chemical methods. Bigham JM, editor-in-chief SSSA. Madison, Wisconsin, USA: Soil Science Society of America Inc.; 1996. pp. 1011-1170. Electronic resource. Available at: https://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/california_waterfix/exhibits/docs/Islands/n_41.pdf (access 12.07.2019)
28. Vasilevich RS, Lodygin ED, Beznosikov VA, Abakumov EV. Molecular composition of raw peat and humic substances from permafrost peat soils of European Northeast Russia as climate change markers. Science of еhe Total Environment. 2018;615:1229-1238. doi: 10.1016/j.scitotenv.2017.10.053
29. Celi L, Schnitzer M, Negre M. Analysis of carboxyl groups in soil humic acids by a wet chemical method. Fourier-transform infrared spectrophotometry, and solution state carbon-13 nuclear magnetic resonance. A comparative study. Soil Science. 1997;162:189-197. doi: 10.1097/00010694-199703000-00004
30. Beznosikov VA, Lodygin ED. High-molecular organic substances in soils. Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences. 2010;1:24-30. In Russian
31. Vasilevich RS, Lodygin ED, Beznosikov VA. Molecular-mass distribution of humus substances tundrain soils of the European north-east Russia. Vestnik SPbSU. Biology. 2015;4:103-111. In Russian
32. Baldock JA, Preston CM. Chemistry of carbon decomposition processes in forests as revealed by solid-state carbon-13 nuclear magnetic resonance. In: Carbon Forms and Functions in Forest Soils. Kelly JM and McFee WW, editor. Madison, Wisconsin, USA: Soil Science Society of America, Inc.; 1995. 89-117 p.
33. Panettieri M, Knicker H, Murillo JM, Madejon E, Hatcher PG. Soil organic matter degradation in an agricultural chronosequence under different tillage regimes evaluated by organic matter pools, enzymatic activities and CPMAS 13C NMR. Soil Biology and Biochemistry. 2014;78:170-181. doi: 10.1016/j.soilbio.2014.07.021
34. Dergacheva MI, Bazhina NL, Ondar EE, Ochur KO, Ryabova NN. Environmentally induced composition and properties of humic acids in soils of Western Tuva. Vestnik Orenburg State University. 2015;10(185):166-169. In Russian
35. Tsybenov YB, Chimitdorzhieva GD, Egorova RA, Gongal’skii KB. The pool of organic carbon and its isotopic composition in cryomorphic quasi-gley chernozems of the Trans-Baikal region. Eurasian Soil Science. 2016;49(1):8-14. doi: 10.1134/S106422931507011X
36. Xu J, Zhao B, Chu W, Mao J, Zhang J. Chemical nature of humic substances in two typical Chinese soils (upland vs paddy soil): A comparative advanced solid state NMR study. Science of The Total Environment. 2017;576:444-452. doi: 10.1016/j.scitotenv.2016.10.118
37. Kleinhempel D. Ein Beitrag zur Theorie des Huminstoffezustondes. Albrecht-Thaer-Archiv. 1970;14(1):3-14. In German
38. Abakumov EV, Trubetskoj O, Demin D, Celi L, Cerli C, Trubetskaya O. Humic acid characteristics in podzol soil chronosequence. Chem. Ecol. 2010;26:59-66. doi: 10.1080/02757540.2010.497758
39. Abakumov E, Lodygin E, Tomashunas V. 13C NMR and ESR Characterization of humic substances isolated from soils of two Siberian Arctic Islands. International J Ecology. 2015;e390591. doi: 10.1155/2015/390591
40. Abakumov E. Characterisation of humic acids isolated from selected subantarctic soils by 13C-NMR spectroscopy. Czech Polar Reports. 2017;7:1-10. doi: 10.5817/CPR2017-1-1
41. Mergelov N, Mueller CW, Prater I, Shorkunov I, Dolgikh A, Zazovskaya E, Shishkov V, Krupskaya V, Abrosimov K, Cherkinsky A, Goryachkin S. Alteration of rocks by endolithic organisms is one of the pathways for the beginning of soils on Earth. Scientific Reports. 2018;8:3367. doi: 10.1038/s41598-018-21682-6
42. Amelung W, Flach KW, Zech W. Climatic effects on soil organic matter composition in the great plains. Soil Science Society of America Journal. 1997;61:115-123. doi: 10.2136/sssaj1997.03615995006100010018x
43. Orlov DS. Soil Chemistry: A Textbook. Moscow: Moscow State University Publ.; 1985. 376 p. In Russian
44. Polyakov V, Zazovskaya E, Abakumov V Molecular composition of humic substances isolated from selected soils and cryconite of the Granfjorden area. Spitsbergen. Polish Polar Research. 2019;40(2):105-120. doi: 10.24425/ppr.2019.128369
Tomsk State University Journal of Biology. 2019; : 6-21
Molecular and elemental composition of humic acids isolated from selected soils of the Russian Arctic
https://doi.org/10.17223/19988591/47/1Abstract
Humic substances, isolated from selected soils of the Russian Arctic, were investigated in terms of molecular composition and stabilization rate. The degree of polar soil organic matter stabilization was assessed with the use of modern instrumental spectroscopy methods. The analysis of humic acid (HAs) preparations showed that aliphatic fragments prevail in the organic matter isolated in polar soils.
The predominance of aliphatic fragments was revealed in HAs from soils located in the coastal zone, which could be caused by regular refreshment of organic matter during sin-lithogenic process and processes of hydrogenation in HAs. Breaking of the C-C bonds and formation of chains with a high hydrogen content, which leads to the formation of aliphatic fragments in HAs, were noted. Data on the calculated atomic ratios of the elements in HAs are given and graphs show the main regularities in the formation of HAs and their properties. The integrated indicators of the molecular composition of humic acids of soils of the Russian Arctic are presented.
The paper contains 4 Tables, 4 Figures and 44 References.
References
1. Anisimov O, Arnalds O, Arnoldusen A, Bockheim J, Breuning-Madsen H, Broll G, Brown J, Desyatkin R, Goryachkin S, Jakobsen BH, Jones A, Konyushkov D, Mazhitova G, McCallum I, Montanarella L, Naumov E, Overduin PP, Nilsson S, Solbakken E, Ping CL, Ritz K, Spaargaren O, Stolbovoy V, Tarnocai C. Soil Atlas of the Northern Circumpolar Region: An initiative of the European Union to support the International Polar YearJRC European Commission. Institute for Environment. Jones A, Principal editor. Luxembourg: Publ. Office of the European Union, 144 p. doi: 10.2788/95795
2. Zubrzycki S, Kutzbach L, Pfeiffer E.-M. 2014. Permafrost-affected soils and their carbon pools with a focus on the Russian Arctic. Solid Earth. 2014;5:595-609. doi: 10.5194/se-5-595-2014
3. Schadel C, Schuur EAG, Bracho R, Elberling B, Knoblauch C, Lee H, Luo Y, Schimel DS. Terrestrial ecosystems and the carbon cycle. Global Change Biology. 1995;1:77-91. doi: 10.1111/gcb.12417
4. Schimel DS. Terrestrial ecosystems and the carbon cycle. Global Change Biology. 1995;1:77-91. doi: 10.1111/j.1365-2486.1995.tb00008.x
5. Davis TN. Permafrost: A Guide to Frozen Ground in Transition. Fairbanks, AK, U.S.A.: University of Alaska Press; 2001. 351 p.
6. Dutta K, Schuur AG, Neff JC, Zimov SA. Potential carbon release from permafrost soils of Northeastern Siberia. Global Change Biology. 2006;12:2336-2351. doi: 10.1111/j.1365-2486.2006.01259.x
7. Polyakov VI, Orlova KS, Abakumov EV. Evaluation of carbon stocks in the soils of Lena River Delta on the basis of application of “dry combustion” and Tyurin’s methods of carbon determination. Biological Communications. 2017;62:67-72. doi: 10.21638/11701/spbu03.2017.202
8. Uchaev AP, Nekrasova OA. Mobile humic substances in the forest-tundra zone podzols. BioClimLand. 2013;1:58-66.
9. Okoneshnikova MV. Current state and prediction of changes in soils of the middle Lena valley (Central Yakutia). Tomsk State University Journal of Biology. 2013;3(23):7-18. doi: 10.17223/19988591/23/1 In Russian
10. Bolter M, Blume H-P, Wetzel H. Properties, formation, classification and ecology of soils: Results from the Tundra Northwest Expedition 1999 (Nunavut and Northwest Territories, Canada). Polarforschung. 2006;73:89-101.
11. Dai XY, Ping CL, Michaelson GJ. Characterizing soil organic matter in Arctic tundra soils by different analytical approaches. Organic Geochemistry. 2002;33:407-419. doi: 10.1111/j.1365-2389.2007.00908.
12. Kutzbach L, Wagner D, Pfeiffer E-M. Effect of microrelief and vegetation on methane emission from wet polygonal tundra. Lena Delta, Northern Siberia. Biogeochemistry. 2004;69:341-362. doi: 10.1023/B:BI0G.0000031053.81520.db
13. Boike J, Kattenstroth B, Abramova K, Bornemann N, Chetverova A, Fedorova I, Frob K, Grigoriev M, Grube RM, Kutzbach L, Langer M, Minke M, Muster S, Piel K, Pfeiffer E-M, Stoof G, Westermann S, Wischnewski K, Wille C, Hubberten H-W. Baseline characteristics of climate, permafrost and land cover from new permafrost observatory in the Lena River Delta, Siberia (1998-2011). Biogeosciences. 2013;10:2105-2128. doi: 10.5194/bg-10-2105-2013
14. Kirpotin SN. Western Siberia in a changing climate. International J Environmental Studies. 2014;71(5):591-594. doi: 10.1080/00207233.2014.945695
15. Cazzolla Gatti R, Callaghan TV, Rozhkova-Timina I, Dudko A, Lim A, Vorobyev SN, Kirpotin SN, Pokrovsky OS. The role of Eurasian beaver (Castor fiber) in the storage, emission and deposition of carbon in lakes and rivers of the River Ob flood plain, western Siberia. Science of the Total Environment. 2018;644:1371-1379. doi: 10.1016/j.scitotenv.2018.07.042
16. Lodygin ED, Beznosikov VA. The molecular structure and elemental composition of humic substances from Albeluvisols. Chemistry and Ecology. 2010;26:87-95. doi: 10.1080/02757540.2010.497759
17. Ejarque E, Abakumov E. Stability and biodegradability of organic matter from Arctic soils of Western Siberia: Insights from 13C-NMR spectroscopy and elemental analysis. Solid Earth. 2016;7:153-165. doi: 10.5194/se-7-153-2016
18. Lodygin E, Beznosikov V, Abakumov E. Humic substances elemental composition of selected taiga and tundra soils from Russian European North-East. Polish Polar Research. 2017;38:125-147. doi: 10.1515/popore-2017-0007
19. Lupachev A, Abakumov E, Gubin S. The influence of cryogenic mass exchange on the composition and stabilization rate of soil organic matter in cryosols of the Kolyma Lowland (North Yakutia. Russia). Geosciences. 2017;7:24. doi: 10.3390/geosciences7020024
20. Zharinova NY, Yamskih AA. Humus characteristics of alluvial dark-humus soils of Krasnoyarsk forest-steep. Tomsk State University Journal ofBiology. 2011;1(13):5-10. In Russian
21. Chefetz B, Salloum MJ, Deshmukh AP, Hatcher PG. Structural components of humic acids as determined by chemical modifi cations and carbon - 13 NMR, pyrolysis and thermochemolysis-gas chromatography/mass spectrometry. Soil Science Society of America Journal. 2002;66:1159-1171. doi: 10.1016/S1001-0742(08)62285-8
22. Szymanski W, Wojtun B, Stolarczyk M, Siwek J, Wascinska J. Organic carbon and nutrients (N, P) in surface soil horizons in a non-glaciated catchment, SW Spitsbergen. Polish Polar Research. 2016;37:49-66. doi: 10.1515/popore-2016-000
23. Lodygin ED, Beznosikov VA, Vasilevich RS. Molecular composition of humic substances in tundra soils (13C-NMR spectroscopic study). Eurasian Soil Science. 2014;47:400-406. doi: 10.1134/S1064229314010074
24. Chukov SN, Abakumov EV, Tomashunas VM. Characterization of humic acids isolated from Antarctic soils by 13C NMR spectroscopy. Eurasian Soil Science. 2015;48:1207-1211. doi: 10.1134/S1064229315110046
25. Glazov MV, Goryachkin SV. Changes in natural zones of the Russian Arctic. Priroda. 1997;5:32-47. In Russian
26. IUSS Working Group WRB World Reference Base for Soil Resources 2014, update 2015. International Soil Classification System for Naming Soils and Creating Legends for Soil Maps. World Soil Resources Reports No. 106. Rome: FAO; 2015. 192 p.
27. Swift RS. Organic matter characterization. In: Soil Science Society of America Book Series. No 5. Methods of soil analysis. Pt 3. Chemical methods. Bigham JM, editor-in-chief SSSA. Madison, Wisconsin, USA: Soil Science Society of America Inc.; 1996. pp. 1011-1170. Electronic resource. Available at: https://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/california_waterfix/exhibits/docs/Islands/n_41.pdf (access 12.07.2019)
28. Vasilevich RS, Lodygin ED, Beznosikov VA, Abakumov EV. Molecular composition of raw peat and humic substances from permafrost peat soils of European Northeast Russia as climate change markers. Science of ehe Total Environment. 2018;615:1229-1238. doi: 10.1016/j.scitotenv.2017.10.053
29. Celi L, Schnitzer M, Negre M. Analysis of carboxyl groups in soil humic acids by a wet chemical method. Fourier-transform infrared spectrophotometry, and solution state carbon-13 nuclear magnetic resonance. A comparative study. Soil Science. 1997;162:189-197. doi: 10.1097/00010694-199703000-00004
30. Beznosikov VA, Lodygin ED. High-molecular organic substances in soils. Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences. 2010;1:24-30. In Russian
31. Vasilevich RS, Lodygin ED, Beznosikov VA. Molecular-mass distribution of humus substances tundrain soils of the European north-east Russia. Vestnik SPbSU. Biology. 2015;4:103-111. In Russian
32. Baldock JA, Preston CM. Chemistry of carbon decomposition processes in forests as revealed by solid-state carbon-13 nuclear magnetic resonance. In: Carbon Forms and Functions in Forest Soils. Kelly JM and McFee WW, editor. Madison, Wisconsin, USA: Soil Science Society of America, Inc.; 1995. 89-117 p.
33. Panettieri M, Knicker H, Murillo JM, Madejon E, Hatcher PG. Soil organic matter degradation in an agricultural chronosequence under different tillage regimes evaluated by organic matter pools, enzymatic activities and CPMAS 13C NMR. Soil Biology and Biochemistry. 2014;78:170-181. doi: 10.1016/j.soilbio.2014.07.021
34. Dergacheva MI, Bazhina NL, Ondar EE, Ochur KO, Ryabova NN. Environmentally induced composition and properties of humic acids in soils of Western Tuva. Vestnik Orenburg State University. 2015;10(185):166-169. In Russian
35. Tsybenov YB, Chimitdorzhieva GD, Egorova RA, Gongal’skii KB. The pool of organic carbon and its isotopic composition in cryomorphic quasi-gley chernozems of the Trans-Baikal region. Eurasian Soil Science. 2016;49(1):8-14. doi: 10.1134/S106422931507011X
36. Xu J, Zhao B, Chu W, Mao J, Zhang J. Chemical nature of humic substances in two typical Chinese soils (upland vs paddy soil): A comparative advanced solid state NMR study. Science of The Total Environment. 2017;576:444-452. doi: 10.1016/j.scitotenv.2016.10.118
37. Kleinhempel D. Ein Beitrag zur Theorie des Huminstoffezustondes. Albrecht-Thaer-Archiv. 1970;14(1):3-14. In German
38. Abakumov EV, Trubetskoj O, Demin D, Celi L, Cerli C, Trubetskaya O. Humic acid characteristics in podzol soil chronosequence. Chem. Ecol. 2010;26:59-66. doi: 10.1080/02757540.2010.497758
39. Abakumov E, Lodygin E, Tomashunas V. 13C NMR and ESR Characterization of humic substances isolated from soils of two Siberian Arctic Islands. International J Ecology. 2015;e390591. doi: 10.1155/2015/390591
40. Abakumov E. Characterisation of humic acids isolated from selected subantarctic soils by 13C-NMR spectroscopy. Czech Polar Reports. 2017;7:1-10. doi: 10.5817/CPR2017-1-1
41. Mergelov N, Mueller CW, Prater I, Shorkunov I, Dolgikh A, Zazovskaya E, Shishkov V, Krupskaya V, Abrosimov K, Cherkinsky A, Goryachkin S. Alteration of rocks by endolithic organisms is one of the pathways for the beginning of soils on Earth. Scientific Reports. 2018;8:3367. doi: 10.1038/s41598-018-21682-6
42. Amelung W, Flach KW, Zech W. Climatic effects on soil organic matter composition in the great plains. Soil Science Society of America Journal. 1997;61:115-123. doi: 10.2136/sssaj1997.03615995006100010018x
43. Orlov DS. Soil Chemistry: A Textbook. Moscow: Moscow State University Publ.; 1985. 376 p. In Russian
44. Polyakov V, Zazovskaya E, Abakumov V Molecular composition of humic substances isolated from selected soils and cryconite of the Granfjorden area. Spitsbergen. Polish Polar Research. 2019;40(2):105-120. doi: 10.24425/ppr.2019.128369
