nitrogénkörforgásokban

The nitrogen cycle, or "nitrogénkörforgás" in Hungarian, describes the biogeochemical cycle by which nitrogen is converted into various chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems. Nitrogen is an essential component of all living organisms, being a key element in amino acids, proteins, and nucleic acids.

The cycle begins with atmospheric nitrogen (N2), which is largely unusable by most organisms. Nitrogen fixation is the process by which atmospheric nitrogen is converted into ammonia (NH3) or other reactive nitrogen compounds. This can occur biologically, primarily by certain bacteria and archaea, or abiotically through processes like lightning or industrial processes.

Once fixed, nitrogen is available to plants, often in the form of ammonium (NH4+) or nitrate (NO3-). Nitrification is the biological oxidation of ammonia to nitrite (NO2-) and then to nitrate. Plants absorb these nitrogen compounds through their roots. Animals obtain nitrogen by consuming plants or other animals.

Decomposition plays a crucial role as organic nitrogen in dead organisms and waste products is converted back into ammonia by decomposers, primarily bacteria and fungi. This ammonia can then re-enter the nitrification process or be converted back to atmospheric nitrogen.

Denitrification is the process by which nitrates are reduced to gaseous nitrogen (N2), returning it to the atmosphere and completing the cycle. This process is carried out by denitrifying bacteria under anaerobic conditions. Human activities, such as the use of fertilizers and the burning of fossil fuels, can significantly alter the natural nitrogen cycle, leading to environmental issues like eutrophication and acid rain.