Nitrogen, an invisible and odorless gas, is a ubiquitous element. It surrounds us in the air, resides within the soil, and forms an integral part of every living cell. From the vast atmosphere to the microscopic components of life, nitrogen’s presence is fundamental, underpinning numerous processes that shape our world.
The Building Block of Life
Nitrogen plays a central role in all living organisms. It is a component of amino acids, the units that form proteins. Proteins perform many functions, including building and repairing tissues, producing enzymes, and enabling cellular processes. Amino nitrogen accounts for approximately 16% of the weight of proteins.
Beyond proteins, nitrogen is also a key ingredient in nucleic acids, specifically deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These molecules are the carriers of genetic information, dictating the blueprint for life. The nitrogenous bases—adenine, guanine, cytosine, thymine (in DNA), and uracil (in RNA)—are the informational units. Additionally, nitrogen is found in adenosine triphosphate (ATP), often called the “energy currency” of the cell. ATP captures chemical energy from food breakdown and releases it to power cellular activities.
Fueling the Food We Eat
Nitrogen is important for agriculture and global food production. Plants acquire nitrogen from the soil, typically in the form of nitrates or ammonium, to synthesize proteins and nucleic acids for growth. This process is a basis for the food chain, as animals and humans obtain nitrogen by consuming plants or other animals.
A natural process known as nitrogen fixation converts atmospheric nitrogen gas into forms usable by plants, primarily through certain bacteria in the soil or in symbiotic relationships with plant roots, particularly legumes. However, natural nitrogen fixation alone cannot meet the demands of feeding a large global population. The industrial production of nitrogen-based fertilizers, largely through the Haber-Bosch process, has increased crop yields. This synthetic ammonia production has helped avert widespread famine and sustains a significant portion of the world’s population.
Nitrogen’s Role in Our Atmosphere
Nitrogen is the most abundant gas in Earth’s atmosphere, making up approximately 78% of dry air. This high concentration contributes to atmospheric pressure and density. Its presence helps regulate environmental processes.
As an inert gas, nitrogen acts as a diluent for oxygen, preventing rapid oxidation and uncontrolled combustion that would occur if oxygen were present in higher concentrations. This inert quality also influences weather patterns and atmospheric stability, creating conditions favorable for life. The stability and non-reactivity of atmospheric nitrogen are main reasons for its abundance.
Everyday Applications and Innovations
Beyond its natural biological and atmospheric roles, nitrogen is harnessed for many industrial and technological applications. Liquid nitrogen, with its low temperature of -196°C, is widely used in medicine for cryopreservation, for long-term storage of biological samples like blood, tissues, and reproductive cells. It is also employed in cryotherapy to treat skin conditions and certain tumors by freezing abnormal tissues.
In the food industry, nitrogen gas is important for modified-atmosphere packaging, where it replaces oxygen to prevent spoilage and rancidity, extending the shelf life of perishable goods. This maintains the quality and freshness of many packaged foods. Nitrogen also creates inert atmospheres in electronics manufacturing, preventing oxidation during processes like soldering and ensuring reliability of sensitive components. Historically, nitrogen compounds have been used in explosives like dynamite and ammonium nitrate, though their main modern application is in fertilizers.