### Organic matter accumulation

In the process of photosynthesis, land plants form 100 - 172 billion tons, and plants of the seas and oceans - 60 - 70 billion tons of biomass per year (in terms of dry matter). The total mass of plants on Earth currently stands at 2,402.7 billion tons, with 90% of this dry mass being pulp. 2402.5 billion tons are spent on land plants, and only 0.2 billion tons on hydrosphere plants (due to lack of light). The total mass of animals and microorganisms on Earth is 23 billion tons, which is about 1% of the total. plant biomass. Of this amount, 20 billion tons are accounted for by land inhabitants, and 3 billion tons - by animals and microorganisms of the hydrosphere.

During the existence of life on Earth, the organic remains of plants and animals accumulated and modified. On land, these organic substances are presented in the form of litter, humus and peat, of which under certain conditions coal was formed in the thickness of the lithosphere. In the seas and oceans, organic residues (mainly of animal origin) settled bottom and were part of sedimentary rocks. When lowering into deeper regions of the lithosphere, these residues formed gas and oil under the influence of microorganisms, elevated temperatures and pressures. The mass of organic matter in litter, peat and humus is estimated at 194, 220 and 2500 billion tons, respectively. Oil and gas amount to 10,000-12,000 billion tons. The content of organic matter in sedimentary rocks reaches 20,000,000 billion tons (carbon).

Especially intense accumulation of dead organic residues occurred 300 million years ago in the Paleozoic era. Wood stocks, and in the last 200 years, coal, oil and gas are used by man to obtain the energy needed in everyday life, industry and agriculture.

### Consistency $CO_2$ in the atmosphere

The formation of organic matter of humus, sedimentary rocks and fossil fuels led significant quantities $CO_2$ from the carbon cycle. In the atmosphere of the earth $CO_2$ it was getting smaller and currently it is only 0.03% (by volume), or (in absolute terms) 711 billion tons in terms of carbon.

In the Cenozoic era, the carbon dioxide content in the atmosphere stabilized and experienced only diurnal, seasonal, and longer geochemical fluctuations. This stabilization is achieved by balanced binding and release. $CO_2$ implemented globally. Binding $CO_2$ during photosynthesis, carbonate formation is compensated by $CO_2$ due to other processes. Annual admission $CO_2$ to the atmosphere in terms of carbon (in billion tons) is due to: respiration of plants - 10, respiration and fermentation of microorganisms - 25, respiration of animals and humans - 1.6, production of people - 5, geochemical processes - 0.051. In the absence of this income, the whole $CO_2$ atmosphere would be bound during photosynthesis in 6-7 years. A powerful reserve of carbon dioxide is the oceans, in the waters of which is dissolved 60 times more $CO_2$ than being in the atmosphere. Photosynthesis, on the one hand, the respiration of organisms and the carbonate system of the ocean, on the other hand, maintain a relatively constant level $CO_2$ in the atmosphere.

However, over the past decades, due to the ever-increasing human burning of fossil fuels, as well as due to deforestation and decomposition of humus, the content $CO_2$ in the atmosphere began to increase by about 0.23% per year. This circumstance can have far-reaching consequences due to the fact that concentration $CO$ , affects the thermal regime of the Earth (see below).

### The greenhouse effect

The surface of the earth receives heat mainly from the sun. Part of this heat goes back into space in the form of infrared rays. Carbon dioxide in the atmosphere, as well as water, absorbs infrared radiation and thus retains a significant amount of heat on Earth (the greenhouse effect). Microorganisms and plants in the process of breathing or fermentation provide 85% of the total $CO_2$ , entering annually into the atmosphere, and as a result have an effect on the thermal regime of our planet.

Upward trend $CO_2$ in the atmosphere due to the burning of huge quantities of oil, gas and other reasons mentioned above, can contribute to an increase in the average temperature on the Earth's surface, which will lead to an acceleration of the melting of glaciers in the mountains and at the poles and flooding of coastal zones. It is possible, however, that an increase in concentration $CO$ : Will enhance the photosynthesis of plants, which will eliminate the excessive accumulation of carbon dioxide. It is known that a change in concentration $CO_2$ in the biosphere acts as an element of feedback.

### The accumulation of oxygen in the atmosphere

Originally in the atmosphere of the earth $O_2$ present in trace amounts. Currently, it is 21% but the volume of air. Emergence and accumulation $O_2$ in the atmosphere is associated with the activity of green plants. Every year during photosynthesis, oxygen enters the atmosphere in an amount of 70-120 billion tons. This oxygen is necessary for the respiration of all heterotrophs - bacteria, fungi, animals and humans, as well as green plants at night.

Of particular importance in maintaining a high concentration $O_2$ in the atmosphere have forests. It is estimated that 1 ha of forest in spring and summer per hour allocates $O_2$ in an amount sufficient for 200 people to breathe.

### Ozone screen

Another major consequence of oxygen evolution by plants is the formation of an ozone screen in the upper atmosphere at an altitude of about 25 km. Ozone ( $O_3$ ) is formed as a result of photo dissociation of molecules $O_2$ under the influence of solar radiation. Ozone delays most of the ultraviolet rays (240-290 nm), which are detrimental to all living things. The possibility of partial destruction of the ozone screen due to atmospheric pollution by industrial and other wastes is a serious problem of protecting the biosphere.

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