lämmastikutsükkel

The nitrogen cycle, or lämmastikutsükkel in Estonian, is 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 element for all life, forming a key component of amino acids and nucleic acids. However, atmospheric nitrogen gas (N2), which is the most abundant form of nitrogen, is largely inaccessible to most organisms.

The nitrogen cycle involves several key processes, each facilitated by specific microorganisms. Nitrogen fixation is the initial step where atmospheric nitrogen is converted into ammonia (NH3) or ammonium (NH4+). This can occur through biological processes, primarily carried out by bacteria, or through industrial processes like the Haber-Bosch method. Nitrification is the subsequent conversion of ammonia into nitrites (NO2-) and then into nitrates (NO3-). Denitrification is the process by which nitrates are reduced back into atmospheric nitrogen gas, completing the cycle. Ammonification, or decomposition, involves the breakdown of organic nitrogen compounds in dead organisms and waste products back into ammonia.

The nitrogen cycle is crucial for maintaining the productivity of ecosystems. However, human activities, such as the use of synthetic fertilizers and the combustion of fossil fuels, have significantly altered the natural balance of the nitrogen cycle, leading to environmental problems like eutrophication and acid rain. Understanding the lämmastikutsükkel is vital for managing these impacts and ensuring the sustainability of natural resources.