Book contents
- Frontmatter
- Contents
- Editor's note
- Acknowledgements
- Notes on translations and definitions
- Abstract
- Preface
- Introduction
- I Thermal-physical, physico-chemical and mechanical processes in freezing, frozen and thawing ground and their manifestation in the permafrost regions
- 1 Thermal-physical processes in freezing and thawing ground
- 2 Water transfer and ice formation in soils
- 3 Physico-chemical and mechanical processes in freezing and thawing ground
- 4 Structure and texture of freezing and thawing soils
- 5 Cryogenic geological processes and phenomena
- II Composition, cryogenic structure and properties of frozen rocks
- III Principles of the formation and development of the frozen strata and layers of seasonal freezing and thawing
- IV Regional features and evolution of permafrost
- V Rational use of frozen ground and environmental protection in the course of economic development of the permafrost regions
- References
- Index
3 - Physico-chemical and mechanical processes in freezing and thawing ground
Published online by Cambridge University Press: 03 November 2009
- Frontmatter
- Contents
- Editor's note
- Acknowledgements
- Notes on translations and definitions
- Abstract
- Preface
- Introduction
- I Thermal-physical, physico-chemical and mechanical processes in freezing, frozen and thawing ground and their manifestation in the permafrost regions
- 1 Thermal-physical processes in freezing and thawing ground
- 2 Water transfer and ice formation in soils
- 3 Physico-chemical and mechanical processes in freezing and thawing ground
- 4 Structure and texture of freezing and thawing soils
- 5 Cryogenic geological processes and phenomena
- II Composition, cryogenic structure and properties of frozen rocks
- III Principles of the formation and development of the frozen strata and layers of seasonal freezing and thawing
- IV Regional features and evolution of permafrost
- V Rational use of frozen ground and environmental protection in the course of economic development of the permafrost regions
- References
- Index
Summary
Chemical reactions and processes in freezing and thawing soils
Essentially the same chemical reactions take place in soils during freezing and thawing and in the frozen state as in unfrozen materials. These reactions are solution, hydration, substitution, oxidation-reduction, ion exchange etc., but in the cold regions they have a number of specific features. For example, solution is less intense because under lower temperatures some salts dissolve at a much slower rate. Apparently, because of low temperatures the permafrost regions contain considerable amounts of the products of chemical interaction between the dissolved substances and water molecules, that is, hydrates and crystalline hydrates. The cation exchange reactions have, probably, a predominant importance for frozen soil, because unfrozen water is a rather concentrated solution, the ions of which actively interact with the ions of the mineral surfaces. Moreover the typical processes in frozen ground are coagulation of sols and formation of colloidal compounds. These processes are predetermined by the characteristic phase transitions of water in the ground (freezing or thawing) which cause dehydration in soils and, consequently, coagulation (on reaching the threshold of coagulation) of organic-mineral compounds. The geochemical processes occurring in the cold regions also have distinct specific features of geochemical processes that play certain specific roles. For example, free water affects seasonally frozen soil intensively only in the warm period of the year. A major role therefore belongs to bound (unfrozen) water which interacts with, and is in dynamic equilibrium with, the ice and soil.
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- Information
- General Geocryology , pp. 120 - 156Publisher: Cambridge University PressPrint publication year: 1998