Search results
Results from the WOW.Com Content Network
Human impact on the nitrogen cycle is diverse. Agricultural and industrial nitrogen (N) inputs to the environment currently exceed inputs from natural N fixation . [ 1 ] As a consequence of anthropogenic inputs, the global nitrogen cycle (Fig. 1) has been significantly altered over the past century.
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes.
There is much overlap between the terms for the biogeochemical cycle and nutrient cycle. Most textbooks integrate the two and seem to treat them as synonymous terms. [5] However, the terms often appear independently. The nutrient cycle is more often used in direct reference to the idea of an intra-system cycle, where an ecosystem functions as a ...
The nitrogen cycle is one of the Earth's biogeochemical cycles. It involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth.
Nitrogen cycle. Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms [1] or entirely within one organism, as in comammox bacteria. The transformation of ammonia to ...
Biological soil crust contributions to the nitrogen cycle varies by crust composition because only cyanobacteria and cyanolichens fix nitrogen. Nitrogen fixation requires energy from photosynthesis products, and thus increase with temperature given sufficient moisture. Nitrogen fixed by crusts has been shown to leak into surrounding substrate ...
Nitrogen is a critical chemical element in both proteins and nucleic acids, and thus every living organism must metabolize nitrogen to survive. Only bacteria and Archaea are able to convert nitrogen gas (N 2 ) to and from soluble ionic compounds that other organisms can metabolize.
Figure 1. The Nitrogen Cycle. Nitric oxide (NO) and nitrous oxide (N 2 O) are intermediates in the denitrification of nitrate (NO 3 −) to nitrogen gas (N 2). Nitric oxide reductase reduces NO to N 2 O. Nitric oxide reductase belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with other ...