Understanding Where Nitrogen is Commonly Found

November 18, 2025 •

4 min read

Nitrogen gas makes up about 78% of Earth's atmosphere, making it the most abundant element in the air we breathe. Despite this abundance, most organisms cannot use atmospheric nitrogen directly, as it must first be converted into a usable form for life to thrive. This critical element is commonly found in the atmosphere, the soil, water, and all living organisms.

Quick Summary

This guide details the major locations and forms in which nitrogen is commonly found, including its presence in the atmosphere, soil, water bodies, and living organisms. It explains how the nitrogen cycle moves the element between these different environmental reservoirs and highlights its diverse applications in industry and agriculture.

Key Points

Atmospheric Abundance: Approximately 78% of Earth's atmosphere is composed of nitrogen gas ($N_2$), though this form is largely inaccessible to most living organisms.
Foundation of Life: Nitrogen is a key component of essential biomolecules, including amino acids, proteins, DNA, RNA, and chlorophyll, making it a cornerstone of all living things.
Soil and Water Cycling: In soil, nitrogen is found in both organic and inorganic forms, cycling between plant residues, microorganisms, and soluble ions like ammonium ($NH_4^+$) and nitrate ($NO_3^−$).
Industrial Utility: Nitrogen's inert and cryogenic properties make it valuable for industrial uses such as food packaging, electronics manufacturing, cryogenic freezing, and as a blanketing gas.
Nitrogen Cycle Engine: The movement and conversion of nitrogen are orchestrated by the nitrogen cycle, a complex process driven primarily by microbes that transform the element into forms usable by life.
Human Impact: Industrial fertilizer production has significantly altered the nitrogen cycle, increasing agricultural yields but also contributing to environmental issues like water pollution and excess greenhouse gas emissions.

Nitrogen in the Atmosphere

Nitrogen's largest reservoir is the Earth's atmosphere, where it exists as a stable, diatomic gas ($N_2$). Comprising approximately 78% of the air, this gaseous form is relatively inert due to the strong triple bond between its two atoms. This stability means that, for biological purposes, atmospheric nitrogen is largely unusable by most organisms until it is converted through a process known as nitrogen fixation. This process can happen naturally through lightning strikes or biologically via specialized bacteria and archaea.

Nitrogen in the Biosphere: All Living Organisms

Nitrogen is a fundamental building block of life and is found within all living organisms, from single-celled bacteria to complex mammals. It is a core component of several vital biological molecules:

Amino Acids: These are the building blocks of proteins, which are essential for cell growth, repair, and function.
Nucleic Acids: Both DNA and RNA, which carry genetic information, are constructed using nitrogen-containing nucleotide bases.
Chlorophyll: This pigment, crucial for photosynthesis in plants, contains nitrogen and is responsible for absorbing light energy.
Energy Transfer Molecules: Molecules like adenosine triphosphate (ATP) contain nitrogen and are responsible for storing and transferring energy within cells.

When organisms die, decomposers like bacteria and fungi break down their tissues, releasing the organic nitrogen back into the environment as ammonium, which can then re-enter the nitrogen cycle.

Nitrogen in the Soil and Water

Nitrogen's journey doesn't stop at the atmosphere and living things; it is also abundant in the soil and water in various forms.

Soil Nitrogen

In the soil, nitrogen exists in both organic and inorganic forms. Organic nitrogen is found in decomposed plant and animal matter (humus). Mineralization, carried out by soil microbes, converts this organic nitrogen into inorganic forms that plants can absorb. The most important of these usable forms are ammonium ($NH_4^+$) and nitrate ($NO_3^−$). Farmers often add synthetic nitrogen fertilizers, like urea and ammonium nitrate, to supplement the soil's natural nitrogen content and increase crop yields.

Waterborne Nitrogen

Nitrogen also enters water bodies through runoff from agricultural lands, atmospheric deposition, and wastewater treatment discharge. In water, it is primarily found as ammonium ($NH_4^+$), nitrite ($NO_2^−$), and nitrate ($NO_3^−$) ions. Excessive nitrogen levels in water can lead to environmental problems such as eutrophication, where high nutrient loads cause excessive algae growth that depletes dissolved oxygen and harms aquatic life.

Industrial Applications of Nitrogen

Beyond its natural reservoirs, nitrogen is harnessed for a wide range of industrial applications due to its inert and cryogenic properties.

Food Packaging and Preservation: Nitrogen gas is used to displace oxygen in food packaging, preventing spoilage and extending the shelf life of perishable products.
Electronics Manufacturing: In the electronics industry, nitrogen creates an inert atmosphere during soldering and semiconductor manufacturing, preventing oxidation and ensuring product quality.
Cryogenic Freezing: Liquid nitrogen is used for rapid freezing in the food industry and for the preservation of biological samples in medicine and research.
Aerospace and Automotive: It is used for tire inflation in aircraft and certain high-performance vehicles, offering better pressure retention.
Chemical Manufacturing: Nitrogen serves as a blanketing gas to create a safe, non-reactive atmosphere for various chemical processes.

Comparison of Nitrogen's Environmental Reservoirs


Feature	Atmosphere	Biosphere (Living Organisms)	Soil & Water	Industrial Applications
Primary Form	Gaseous ($N_2$)	Organic (proteins, nucleic acids)	Inorganic ($NH_4^+$, $NO_3^−$) & Organic	Gaseous ($N_2$), Liquid ($LN_2$)
Key Characteristic	Inert and stable due to strong triple bond	Essential for all life forms; dynamic transfer through food webs	Key component of the nitrogen cycle; can be bioavailable or locked up	Inertness and cryogenic properties; highly versatile
Availability	Abundant but largely inaccessible to most organisms	Limited by food chain and microbial decomposition rates	Variable availability influenced by microbial activity and human input	Easily accessible in gaseous and liquid forms for targeted uses
Impact of Excess	Relatively benign, except for human-induced oxide emissions	Accumulation can lead to toxicity in certain organisms	Can cause harmful eutrophication and groundwater contamination	Requires careful management to prevent environmental runoff

The Role of the Nitrogen Cycle

The movement of nitrogen between these different environmental compartments is driven by the nitrogen cycle. This complex biogeochemical process ensures that nitrogen is continuously converted between its various forms, making it available to different organisms at different stages. Microbes play a central role, facilitating key processes such as nitrogen fixation, nitrification, and denitrification. Human activities, particularly the industrial production of fertilizers via the Haber-Bosch process, have significantly altered this natural cycle, increasing the amount of bioavailable nitrogen in the environment. This has both increased crop yields and caused negative ecological consequences.

Conclusion

Nitrogen is a ubiquitous and vital element that is commonly found in nearly every part of our world. From the vast, unreactive reservoir in the atmosphere to its essential role in the very genetic code of life, its presence is felt throughout all biological and environmental systems. The continuous cycling of nitrogen through the atmosphere, soil, water, and living matter underscores its importance to the planet's health. While crucial for agriculture and many industries, understanding and managing its movement is key to mitigating the environmental impacts of human intervention in this critical natural process. This knowledge is essential for fostering sustainable practices and protecting our environment for future generations. For more in-depth information, you can explore the extensive work on the topic presented by institutions like the University of Missouri Extension.

Frequently Asked Questions

In the atmosphere, nitrogen is found primarily as a stable, inert diatomic gas ($N_2$), which makes up about 78% of the air we breathe.

Nitrogen gets into living things through nitrogen fixation, a process where bacteria and lightning convert atmospheric nitrogen ($N_2$) into usable compounds like ammonia ($NH_3$) and nitrates ($NO_3^−$), which plants can then absorb from the soil.

Nitrogen is crucial for plants because it is a key component of chlorophyll, which is necessary for photosynthesis. It is also a major part of amino acids, the building blocks for proteins needed for cell growth.

Organic nitrogen is found in decomposed plant and animal matter (humus) and is not directly usable by plants. Inorganic nitrogen, like ammonium and nitrate, is a usable form created when microbes break down organic matter through a process called mineralization.

Excess nitrogen in water can lead to eutrophication, a condition where high nutrient levels cause excessive algal growth. When the algae die and decompose, they deplete dissolved oxygen, which can cause fish kills and harm aquatic ecosystems.

In food packaging, nitrogen gas is used to replace oxygen in order to create an inert atmosphere. This prevents oxidation, slows down bacterial growth, and extends the shelf life of perishable products.

Yes, the nitrogen in your body originates from the food you eat, which assimilated nitrogen from the environment. This nitrogen is part of the same global cycle that includes the atmospheric nitrogen pool, but it has been converted into biologically available organic compounds like proteins and DNA.