From Big Medical Encyclopedia

GEOCHEMISTRY — the science studying chemical constitution and chemical evolution of Earth, pattern of prevalence and natural migration of distribution, dispersion and concoction of chemical elements and their connections in its geospheres (covers). From the point of view of biology and G.'s medicine — science about natural and technogenic chemical medium of life. Is a source of data on migration, dispersion and concoction of biogenic chemical elements and natural biogenic forms of their connections.

The term «geochemistry» was entered in 1838 by Shenbeynom (Ch. F. Schonbein, 1799 — 1868) working in Switzerland though already earlier G.'s ideas were developed on the basis of geology and mineralogy it. geologist Bishoff (Page A. Bischoff, 1792 — 1870), etc. The first generalizations of quantitative data on distribution of chemical elements in the nature were made in 1882 by an amer. the geochemist Clark (F. W. Clarke, 1847 — 1931), the main problems of G. were formulated by the Soviet scientists V. I. Vernadsky in kN. «Sketches of geochemistry» (1927) and A. E. Fersman (1883 — 1945) in his four-volume «Geochemistry» which left in 1933 — 1939 and also Norwegians, the geochemist Goldshmidt (V. M of Goldschmidt, 1888 — 1947) — the founder of the first large scientific center of geochemical researches.

The main objective of G. — clarification of dependence between a structure of atoms of chemical elements and their behavior at various thermodynamic and physical. - chemical conditions of geospheres of Earth, establishment of unity of evolution of life and the geochemical environment, chemical composition of crust.

In G. are applied to studying of elementary structure and forms of connections of objects of geospheres physical. and chemical researches, and also mathematical methods and methods of modeling of natural processes (e.g., action of high and ultrahigh temperatures and pressure the upon chemical processes happening in geospheres).

Represents the complex science which is closely connected with a number of related subjects: with geology, with its sections — mineralogy and petrography, physical. chemistry and chemistry of solutions, atomic physics, astrophysics, geography, and also with biol, the sciences opening new ways of studying of living material, a role of biogenic processes to migrations of chemical elements and their biogenic connections, etc.

In G. problems and sections which grow in separate geochemical disciplines can be allocated: Of magmatism (formation of primary crystal breeds, experimental G. of deep processes); Of sludge formation (sedimentation of silicates, carbonates, clays, compounds of iron, manganese and so forth); Of a hyperkinesia (aeration of rocks and formation of soils); Of a metamorphism (chemical change of rocks under the influence of water, temperatures, pressure which are followed by recrystallization without fusion); Of separate chemical elements and their geochemical cycles; regional G. and geochemical provinces; Of the atmosphere (chemical composition of the atmosphere, its evolution, underground atmospheres of soils, porous breeds); Of the hydrosphere (G. of the ocean and continental waters); biogeochemistry (see) and G. of organic matter (studying of life as geochemical factor and influence of conditions of the geochemical environment on evolution of life); a kosmokhimiya (studying of prevalence and distribution of chemical elements in space, meteorites, planets, stars; chemical evolution of Solar system, galaxies); Of evolution of Earth (origin of terrestrial covers, evolution of the biosphere); Of energy resources of Earth; Of isotopes; Of ore formation and geochemical methods of searches of minerals; crystal chemistry and isomorphism; physical. - chemical mechanisms of migration of elements, etc.

chemical mosaicity of distribution in the biosphere of pedogenic breeds, soils, waters, forage and food plants with various chemical elementary structure Was established that gave the grounds for division into districts of the biosphere (see. Biogeochemical division into districts ) and allocations of regions and subregions (see. Biogeochemical provinces ) with a shortcoming or surplus of certain chemical elements. In such territories are open the local blights, animals and the person caused by a shortcoming or surplus of the SI With, Zn, Mo, Sr, Ni, Cd, Cr, Mn, Pb, Li, B, I, F, Se and other elements.

B of communication with studying of reactions of organisms to concentration of chemical elements in the environment developed in G. a recent trend — geochemical ecology (see). It is established that influence on organisms of certain biogenic chemical elements can be connected with existence and concentration among others, the elements accompanying them. So, e.g., spread of a local craw depends on concentration in the environment of Co, Mn, Cu and other elements influencing exchange of iodine. The geochemical ecology gained practical value since by its methods potentially dangerous territories in the local relation come to light.

The problem of possible influence of mineral and microelement composition of the geochemical environment on the course of not local diseases at which in an organism exchange of these elements is broken is of considerable interest.

These G. gained also applied value for development of problems of himization of the national economy — use of mineral and microelement fertilizers and top-dressings microelements of page - x. animals in the conditions of various geochemical environments.

Cannot but participate also in active solution of problems, arising in connection with environmental pollution and its protection.

In the USSR in 1927 I. Vernadsky created large scientific center — Biogeochemical laboratory Academy of Sciences of the USSR (Leningrad, Moscow). Since 1947 the center of geochemical researches in the USSR is Ying t of geochemistry and analytical chemistry of V. I. Vernadsky of Academy of Sciences of the USSR (Moscow) created by the Soviet geochemist academician A. P. Vinogradov. The biogeochemical laboratory remained as a part of it in-that.

On the basis of V. I. Vernadsky and A. E. Fersman's works in the USSR there was a school of the Soviet geochemists and biogeochemists.

The main international periodical according to G. — the Geochimica et Cosmochimica Acta magazine issued since 1950 (Oxford — New York) in the USSR — the Geokhimiya magazine — since 1956 (Moscow).

Bibliography: Vernadsky V. I. Sketches of geochemistry, L., 1927; Vinogradov A. P. Geochemistry of rare and scattered chemical elements in soils, M., 1957, bibliogr.; Kovalsky V. V. Geochemical ecology, M., 1974, bibliogr.; Mason B. Fundamentals of geochemistry, the lane with English, M., 1970; Tugarinov A. I. General geochemistry, M., 1973; Fersman A. E. Geochemistry, t. 1 — 4, L., 1933 — 1939.

V. V. Kovalsky.