The Nitrogen Cycle | AQA A-Level Environmental Science Revision | Primrose Kitten

Nitrogen gas

Element constituting 78% of the atmosphere, exists as N2 molecule with a triple bond

Bond found in nitrogen gas

Triple covalent bond

Enzyme

Biological catalyst that speeds up the rate of reaction

Nitrous oxide gases (NOx)

Form of nitrogen found in the atmosphere

Dissolved nitrates (NO3)

Form of nitrogen found in the hydrosphere

Ammonium ions (NH4)

Form of nitrogen found in the hydrosphere and biosphere where they are used to make amino acids and proteins

Decomposition

Breakdown of dead organic matter to release ammonia/ammonium ions into the soil

Nitrogen fixation

Conversion of nitrogen gas into a more usable form by breaking the triple bond

Nitrification

Conversion of ammonium ions into nitrites and then nitrates in the soil

Denitrification

Conversion of nitrates in the soil to nitrogen gas released into the atmosphere

Haber process

Artificial process to make inorganic fertilizers by combining nitrogen and hydrogen. Form of nitrogen fixation

Ionization

Lightning causes oxygen and nitrogen to fuse, creating oxides of nitrogen. Form of nitrogen fixation

Nitrogen fixation by soil bacteria

Free-living bacterial species in the soil with the enzyme to break the triple bond in nitrogen gas

Nitrogen fixation in leguminous crops

Symbiotic relationship with nitrogen-fixing bacteria in root nodules of legumes

Ammonification

Formation of ammonium ions from dead organic matter by soil bacteria

Nitrifying bacteria

Convert ammonium ions into nitrites and then nitrates in the soil

Aerobic

Requiring oxygen to complete a process, such as nitrification by certain bacteria.

Nitrogen Cycle

The continuous cycling of nitrogen between different reservoirs, involving processes like nitrification, denitrification, and nitrogen fixation.

Eutrophication

The process where an excessive amount of nutrients, often from fertilizers, leads to an overgrowth of algae, reducing oxygen levels and harming aquatic organisms.

Nitrates

Inorganic compounds containing nitrogen and oxygen, released into the soil from fertilizers and contributing to eutrophication and greenhouse gas emissions.

Buffer Strip

An area of land near rivers left free from crops and fertilizers to prevent leaching of fertilizers into the water.

Catalytic Converter

A chamber in a car's exhaust pipe containing a metal catalyst, such as platinum, that reduces nitrous oxide gases back into nitrogen and oxygen before release into the atmosphere.

Leguminous Crops

Plants that have nitrogen-fixing bacteria in their root nodules, reducing the need for inorganic fertilizers.

Organic Fertilizers

Fertilizers derived from natural sources, such as manure, that release nitrogen slowly, reducing the chance of leaching.

Urea Sprays

Sprays used in an industrial setting to react with nitrogen oxides and oxygen in the air, converting them to nitrogen, carbon dioxide, and water to prevent nitrous oxide release.

Agricultural Aeration

Farming activities that increase the oxygen content in the soil, promoting nitrification and reducing denitrification.

Soil Compaction

The process of soil particles being pressed together, reducing air spaces and promoting denitrification in agricultural soils.

Inorganic Fertilizers

Fertilizers produced through chemical processes, releasing large volumes of nitrates into the soil and contributing to environmental damage.

Eutrophication Impact

The environmental consequences of excessive nutrient release, including algal blooms, oxygen depletion, and harm to aquatic organisms.

NOx Impact

The environmental impact of nitrogen oxide gases, including ozone depletion, global warming, and increased UV exposure.