Nitrogen and Phosphorus Cycles

Nitrogen

A colorless, odorless gas that makes up for about 78% of the Earth’s atmosphere and is essential for life as it is a key component of amino acids and nucleic acids.

Nitrogen cycle

The Series of natural processes by which nitrogen is converted between ist various chemical forms, including fixation, nitrification, and denitrification.

Triple Bond (N₂)

The strong chemical bond between two nitrogen atoms in molecular nitrogen, making it inert.

Fixation

The process of converting atmospheric nitrogen into a form that organisms can use, typically ammonia.

Legumes

A group of plants that have symbiotic relationships with nitrogen

Nitrogen Fixation

The process of converting atmospheric nitrogen into ammonia or related compounds, making it biologically available for plants.

Bacterial Fixation

The process where certain bacteria convert atmospheric nitrogen into ammonia.

Biological fixation

A key aspect of nitrogen fixation, involving living organisms like bacteria and cyanobacteria that convert nitrogen gas into organic forms.

Blue-green algae

Photosynthetic bacteria that can fix atmospheric nitrogen: they play a crucial role in nitrogen cycling, particularly in water bodies.

Cyanobacteria

Cyanobacteria are a type of bacteria that can make their own food through photosynthesis, like plants.

Nitrogen fixer

An organism, particularly certain bacteria and blue

Environmental fixation

The conversion of nitrogen gas into biologically available forms through physical and chemical processes, such as lightning or industrial methods

Human impact

The influence of human activities, such as agriculture and industrial processes, on the nitrogen cycle, often leading to environmental issues like pollution.

Nitrates

The oxidized form of nitrogen (NO₃⁻) that is often used by plants as a nutrient.

Nitrites

The intermediately produced form of nitrogen (NO₂⁻) in the nitrification process, less common than nitrates.

Nitrosomonas

Bacteria that play a role in the nitrification process by oxidizing ammonia to nitrite.

Nitrobacter

Bacteria that convert nitrite into nitrate, completing the nitrification process.

Synthetic Nitrogen

Nitrogen compounds produced artificially for use in fertilizers, often derived from the Haber

Atmospheric nitrogen

The nitrogen gas (N₂) present in Earth's atmosphere, which is abundant but not directly usable by most organisms.

Organic nitrogen

Nitrogen found in organic compounds, such as amino acids and proteins, which are essential for life.

Nitrification

The biological process where ammonia is converted into nitrites and then nitrates by nitrifying bacteria.

Ammonification

The process where organic nitrogen compounds are broken down into ammonia, often by decomposers.

Assimilation

The uptake of nitrates and ammonia by plants and microorganisms, incorporating them into organic molecules.

Decomposers

Organisms that break down dead organic material, releasing nutrients back into the soil, including nitrogen.

Denitrification

The process by which nitrates are reduced to nitrogen gas (N₂) or nitrous oxide (N₂O), returning nitrogen to the atmosphere.

Detritus

Organic matter that is decomposing or in decay, serving as a source of nutrients for soil.

Eutrophication

The excess nutrient enrichment of water bodies, often due to runoff containing nitrates and phosphates, leading to algal blooms and oxygen depletion.

Combustion

A chemical process where organic matter is burned, releasing nitrogen oxides (NOₓ) and contributing to air pollution.

Nitrogenase

An enzyme complex that catalyzes the nitrogen fixation process, allowing some bacteria to convert N₂ into ammonia.

Anammox

A biological process where anaerobic bacteria convert ammonium (NH₄⁺) and nitrite (NO₂⁻) into nitrogen gas (N₂) under low oxygen conditions

Phosphorus

An essential macronutrient for plants and animals, necessary for ATP, DNA, and cellular membranes.

Phosphorus Cycle

The series of processes that move phosphorus through the lithosphere, hydrosphere, and biosphere, including weathering, absorption by plants, and return to the soil.

Phosphorus absorption

The process through which plants and organisms take up phosphorus, primarily in the form of phosphate ions, from the soil.