Description

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Context

Nitrogen is fifth-most abundant element in the universe, ~78% of Earth's atmosphere.

Central to life as it is present in DNA, proteins, ATP (energy molecule) and vital bodily processes like nerve transmission and blood flow.

While essential reactive forms of nitrogen are now causing environmental damage on a global scale.

Aspect	Details
Symbol	N
Atomic Number	7
Molecular Form in Atmosphere	N₂ (Diatomic Nitrogen)
Key Biological Roles	Building block of amino acids, proteins, nucleic acids (DNA/RNA) Vital for chlorophyll in plants
Industrial Uses	Fertilisers (ammonia, ammonium nitrate) Explosives (TNT, nitroglycerine) Pharmaceuticals
Environmental Impacts	Eutrophication Greenhouse gas (N₂O) emissions Smog and acid rain formation
Key Processes in Nature	Nitrogen fixation Nitrification Denitrification
Major Human Interventions	Haber-Bosch process Excessive fertiliser use
Major Concerns Today	Nitrous oxide as a potent greenhouse gas Dead zones in oceans due to nitrate runoff

Process	Description
Nitrogen Fixation	Atmospheric N₂ converted to ammonia (NH₃) by bacteria or lightning
Nitrification	Conversion of ammonia into nitrites (NO₂⁻) and nitrates (NO₃⁻)
Assimilation	Plants absorb nitrates to form proteins and nucleic acids
Ammonification	Decomposition of organic nitrogen back into ammonia
Denitrification	Conversion of nitrates back into atmospheric N₂ by bacteria

Discovery

Fritz Haber (1907) — synthesized ammonia from atmospheric nitrogen.

Carl Bosch (BASF) — scaled it industrially with iron catalysts.

Impact

Enabled mass production of fertilisers.

Doubled global food production capacity → Rapid population growth.

Also facilitated chemical warfare (chlorine, mustard gas).

Dual-Use Nature

Fertilisers (feeding people) and Explosives (warfare).

Overuse of Fertilisers

Ammonium nitrates easily leach into water bodies → causing eutrophication.

Algal blooms → Oxygen depletion → Dead zones in oceans (e.g., Gulf of Mexico).

Air Pollution

NO and NO₂ gases (NOₓ) from engines contribute to smog, acid rain, and respiratory diseases.

Greenhouse Gas Effect

N₂O (Nitrous Oxide)

Third most important greenhouse gas after CO₂ and CH₄.

Traps heat in the troposphere.

300 times more potent than CO₂ per molecule.

Major contributor: industrial agriculture (excessive nitrogen fertiliser use).

Concern	Implication
Climate Change	N₂O contributes significantly to global warming.
Biodiversity Loss	Eutrophication destroys aquatic ecosystems.
Human Health Risks	Air pollution from NOₓ causes asthma, lung diseases.
Soil Health Degradation	Over-fertilisation damages natural soil fertility.