62 V. A. SOKOLOV 



mainly took place on the surface of the Earth, gave rise to the process of photo- 

 synthesis, i.e. the process by which plants extract CO2 from the atmosphere. In 

 plants CO2 enters into a reaction whereby the carbon is used for the building of 

 organic substances while the oxygen is given off into the atmosphere. Another 

 extremely important process is that of the decay and oxidation of dead organisms 

 owing to the action of bacteria and various chemical factors (the action of O», 

 H2O, etc.). The products of this decay are given off into the atmosphere, mainly 

 in the form of CO2. 



A small part of the carbon of organisms is transformed into stable compounds 

 which are not susceptible to bacterial action and these compounds are buried 

 in sedimentary deposits. The total mass of carbon which has left the atmosphere 

 in this way to be laid down in sedimentary formations amounts to 1-2 x lo^^ 

 metric tons. The amount of O2 thus liberated amounts to 2 -6-5 -2 x 10^'' metric 

 tons. The amount of O2 which has been given off is many times greater than 

 that in the atmosphere at present (about i x 10^ ^ metric tons). 



The supplies of CO2 in the atmosphere were replenished by the continual 

 emission of it from magmatic formations through volcanoes and by other routes. 

 Study of this problem shows that the total amount of CO2 reaching the atmos- 

 phere from magmatic formations during the last 500 million years alone is very 

 great and would account for all the organic carbon contained in sedimentary 

 formations. 



Study of the gases of soils and bogs indicates that such gases, apart from 

 oxygen, have been formed and given off into the atmosphere as a result of bio- 

 chemical processes. The air in the soil contains, on an average 1-2P/0 of CO2 

 which passes, by gaseous exchange, into the atmosphere. Gas surveys have shown 

 that the air of the soil contains, in addition to CO2, methane in concentrations 

 of io~3 — iO"4o/ç^, jn ^he same work (1937-9) dinitrogen monoxide (NoO) was 

 found to be ubiquitous in the air of soils in concentrations of lO"^ — I0"^% 

 [20]. The gases of bogs are mainly composed of CH4, COo and N2. Heavier 

 hydrocarbons than methane are practically absent [14, 21]. As a result of the 

 vital activities of organisms there reach the atmosphere small quantities of other 

 volatile substances (Hg, CO, NH3, HoS, ethers, terpenes etc.) as well as the gases 

 mentioned above. In regions where there are oil- and gas-bearing formations 

 one may often observe the emission of gaseous hydrocarbons (CH4, etc.) in the 

 form of jets. Such jets of CHj may also be observed emanating from coal 

 seams. 



Whether or not CO, H, CH.4 and other hydrocarbons remain in the atmos- 

 phere depends on the absence or presence of oxygen. The presence of oxygen 

 and of ozone formed from it (by the action of solar radiation and electrical dis- 

 charges in the atmosphere), leads to the oxidation of hydrocarbons, CO and H2, 

 as ozone acts on them at room temperature and even lower. The amount of 

 hydrocarbons given off during these processes is very great and, if there were no 

 oxidation of them in the atmosphere, they would be present there in considerable 

 concentrations [14]. The absence of methane from the contemporary atmosphere 

 can hardly be attributed to its dissipation from the outer layers, for, in that 

 case the heavier hydrocarbons (C2-C4) would remain in the atmosphere. Careful 



