Almost every schoolboy knows that the cyclesubstances in the biosphere, accompanied by the transformation of energy, is the basis of the existence of nature and everything associated with it. Very schematically this cycle can be represented as follows. Existing living organisms in nature consume a large amount of mineral resources from the same nature, and after their death, in the form of various chemical elements, return to the same natural environment, thus forming a cycle of substances in the biosphere. This process is also called the biogenic process, and the place of its flow is the atmosphere, lithosphere and hydrosphere. The cyclical nature and frequency of the phenomena of the transformation of substances on different cycles determined the name - the cycle.
Almost all living organisms, without exceptionparticipate in this cycle. For example, green plants consume, in the air, carbon dioxide, minerals, and release oxygen into the environment.
Representatives of the fauna breathe in the same oxygen,which is allocated by plants, and by eating these plants, digest and process organic substances. In addition, after the death of plants and animals, their remains are processed by various bacteria with the formation of carbon dioxide and the conversion of organic compounds into minerals.
Then the cycle of substances in the biosphere is a processtransformation and movement of substances, continues in the soil where these minerals enter, and then, in turn, are absorbed by the plant world. If to sum up this cycle at the atomic level, a fairly simple conclusion follows: atoms of some of the most basic chemical substances make a continuous process of migration not only from one organism to another, but from one kind of environment to another - consistently present in soil, atmosphere and hydrosphere.
The number of such cycles is practically infinite, kFor example, it is estimated that atmospheric oxygen in its entirety in just two to a few thousand years passes through living organisms. The same movement makes and carbon dioxide, only then the cycle lasts much less time - only 200-300 years. In the framework of such a process, which is the cycle of substances in the biosphere, one such closed circle of circulation is called a biogeochemical cycle.
What determines such a cycle? Unfortunately, for the time being there are no exhaustive, and, most importantly, complete answers to this question. It is possible to assert with a sufficient degree of reliability that one of the reasons is resource limitedness of our planet. Another option can be the reliance on the teaching of the great Vernadsky about the biosphere, which affirms the existence of cosmic turnover, which determines not only the cycle of substances, but also the change in the rational content of the universe. It is recognized that all types of cycles, however much we localize them in time and space, have one property common to all. All of them are connected with the processes of energy exchange. Initially, the energy of the Sun acts as the basis of the cycle. Then it is transformed into various forms of energy of chemical and physical transformations, and therefore one can speak about the cycle of energy potential concluded in the biosphere. The stability of the processes of energy and biological circulation is the main condition for the normal and stable state of the biosphere.
As already mentioned, one of the most "active"participants "of the circuit is carbon. The presence of this element in almost all organic substances explains the carbon cycle in the biosphere quite logically. In the process of photosynthesis, carbon is assimilated from the biosphere zones by plants and converted to carbohydrates. With the breath of living organisms, the reverse process occurs, and as a result, its huge reserves are being spent in this cycle of carbon. The main factors that determine the circulation of carbon are respiration and photosynthesis.
One of the main elements of allorganic matter is nitrogen. It, as a necessary component, contains ATP, proteins, nucleic acids. Nitrogen is found primarily in the atmosphere, and its molecular formula does not allow plants to directly use it. Therefore, plants consume nitrogen in the form of inorganic substances. The methods by which nitrogen enters the ground or water are different, therefore the nitrogen cycle in the biosphere is quite diverse. For example, some nitrogen compounds are formed in the atmosphere during thunderstorms. With rain or sinks, they enter rivers, soil, and lakes, from where they are later absorbed by plants.
Apparently, in all cases, living organisms are the basis for the formation of the circulation of substances in the biosphere.