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  2. Human impact on the nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Human_impact_on_the...

    Approximately 78% of Earth's atmosphere is N gas (N 2), which is an inert compound and biologically unavailable to most organisms.In order to be utilized in most biological processes, N 2 must be converted to reactive nitrogen (Nr), which includes inorganic reduced forms (NH 3 and NH 4 +), inorganic oxidized forms (NO, NO 2, HNO 3, N 2 O, and NO 3 −), and organic compounds (urea, amines, and ...

  3. Reactive nitrogen - Wikipedia

    en.wikipedia.org/wiki/Reactive_nitrogen

    Reactive nitrogen ("Nr"), also known as fixed nitrogen [1], refers to all forms of nitrogen present in the environment except for molecular nitrogen (N 2 ). [ 2 ] While nitrogen is an essential element for life on Earth, molecular nitrogen is comparatively unreactive, and must be converted to other chemical forms via nitrogen fixation before it ...

  4. Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_cycle

    Human activities have also dramatically altered the global nitrogen cycle by producing nitrogenous gases associated with global atmospheric nitrogen pollution. There are multiple sources of atmospheric reactive nitrogen (Nr) fluxes. Agricultural sources of reactive nitrogen can produce atmospheric emission of ammonia (NH 3), nitrogen oxides (NO

  5. Nutrient pollution - Wikipedia

    en.wikipedia.org/wiki/Nutrient_pollution

    Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients.It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth. [1]

  6. Pnictogen - Wikipedia

    en.wikipedia.org/wiki/Pnictogen

    Nitrogen is a component of molecules critical to life on earth, such as DNA and amino acids. Nitrates occur in some plants, due to bacteria present in the nodes of the plant. This is seen in leguminous plants such as peas [clarification needed] or spinach and lettuce. [citation needed] A typical 70 kg human contains 1.8 kg of nitrogen. [14]

  7. Biological roles of the elements - Wikipedia

    en.wikipedia.org/wiki/Biological_roles_of_the...

    The noble gases helium, neon, argon, krypton, xenon are nonreactive and have no known direct biological role — albeit xenon nevertheless very surprisingly exhibits both anesthetic and neuroprotective side-effects despite usually being considered "chemically inert," and can activate at least one human transcription factor. (Radon is ...

  8. Nitrogen - Wikipedia

    en.wikipedia.org/wiki/Nitrogen

    Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System.

  9. Respiratory burst - Wikipedia

    en.wikipedia.org/wiki/Respiratory_burst

    Respiratory burst requires a 10 to 20 fold increase in oxygen consumption through NADPH oxidase (NOX2 in humans) activity. NADPH is the key substrate of NOX2, and bears reducing power. Glycogen breakdown is vital to produce NADPH. This occurs via the pentose phosphate pathway. The NOX2 enzyme is bound in the phagolysosome membrane.