The interaction of all components of the biosphere is carried out through the exchange of matter and energy. The basis of this interaction is the cycle of substances - these are the repeating processes of transformation and migration of substances in nature, which have a cyclic nature of varying degrees of severity. These processes occur with the participation of solar energy and the Earth’s internal energy.
The geological (large) cycle and its biological (small) and anthropogenic cycles are distinguished.
The geological cycle of substances is the redistribution of elements between the biosphere and lithosphere, which occurs under the influence of endogenous (internal) and exogenous (external) processes. Over millions of years, rocks are destroyed, and weathering products are carried by water streams into the oceans. An insignificant part of minerals returns to land as a result of evaporation of moisture and precipitation, and the cycle is closed. The bulk of weathering products remains on the ocean floor, where sedimentation occurs. Geological epochs are changing, sea regressions, tectonic plate movements , mountain building occur, and these strata are again on land - the geological cycle of substances begins a new round. It should be noted that the symbol of this cycle is not a circle, but a spiral, since, due to the extended time frames, each new cycle differs significantly from the previous one.
Of great importance in the life of the biosphere is the so-called hydrological cycle, in which land, atmosphere and ocean participate. This is the water cycle, which also refers to the geological (large) cycle. Its driving force is the energy of the sun, under the influence of which evaporation occurs. Water molecules in the form of gas rise into the atmosphere, where they are cooled and condensed. Clouds form that produce precipitation. If precipitation falls into the ocean, the cycle closes (evaporation, etc.).
Water entering the earth has two paths: surface runoff and infiltration. In the first case, she returns to the ocean, closing the cycle, and in the second she is waiting for a long and interesting journey. Seeping down through cracks and pores, it reaches the water-resistant layer, replenishing groundwater, and then moves in the horizontal direction until it finds an exit to the surface. In this way sources are formed that feed rivers, lakes, ponds, and swamps. During this “journey”, part of the water remains in the surface layer of the soil (capillary moisture), from where it evaporates into the atmosphere, and part is used by plants, on the leaves of which evaporation also occurs (transpiration).
Another component of the geological cycle is the biological cycle of substances, the driving force of which is the activity of living organisms. This cycle looks as follows.
- Water, carbon and nutrients are accumulated by plants (autotrophs) and animals (heterotrophs) that feed on these plants.
- Living organisms die, and under the influence of saprophytes (fungi, bacteria, worms), decay products decompose to mineral components.
- Inorganic substances are again used by autotrophs for the synthesis of organic substances - the biogeochemical circulation of substances continues.
Such processes occur in each ecosystem and include the cycles of individual elements: oxygen, nitrogen, carbon, sulfur, phosphorus, iron, etc. All living organisms that exist on the planet participate in them. The role of bacteria in the cycle of substances is great - they participate in soil formation, water purification, the accumulation of certain elements (nitrogen-fixing bacteria), the decomposition of organic substances (destructors), redox reactions (aerobic bacteria), and many other processes in the biosphere.