Why is nitrogen the most common element in the earths atmosphere?
The answer lies mostly in three facts:
1. nitrogen is volatile in most of its forms
2. it is unreactive with materials that make up the solid earth
3. it is very stable in the presence of solar radiation.
To understand the abundance of N in the atmosphere, it is useful tocompare it to O (the next most abundant element in the atmosphere).Compared to O, N is 4 times as abundant in the atmosphere. However, we must also consider the relative abundances of O and N over the entire Earth (oxygen is about 10,000 times more abundant). These earthly abundances overallreflect the composition of the material from which the Earth originallyformed and the process of Earth's accretion. Oxygen is a major componentof the solid earth, along with Si and elements such as Mg, Ca and Na.Nitrogen is not stable as a part of a crystal lattice, so it is notincorporated into the solid Earth. This is one reason why nitrogen isso enriched in the atmosphere relative to oxygen. The other primary reasonis that, unlike oxygen, nitrogen is very stable in the atmosphereand is not involved to a great extent in chemical reactions thatoccur there. Thus, over geological time, it has built up in the atmosphereto a much greater extent than oxygen. It is important to knowthat both nitrogen and oxygen are intimately involved with thecycle of life on the planet, but that chemicals cycle through thismaterial on a short time scale relative to the geological processesthat have, over time, made the earth what it is today (compositionallyand physically). N and O are found in the living biosphere and fossilorganic matter (and both are soluble in sea water too). But, only a smallfraction (less than 1% for N and much, much less than 1% for O) of thetotal for these element on the planet are to be found in these places.
Dr. Ken Rubin, Assistant Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu HI 96822
Return to the Ask-An-Earth-Scientist © pageI'm an Earth Science enthusiast with a deep understanding of the topic at hand. My knowledge spans various aspects of geology, atmospheric science, and the Earth's composition. To establish my credibility, I'll delve into the concepts discussed in the article about the abundance of nitrogen in Earth's atmosphere.
Nitrogen's prevalence in the Earth's atmosphere can be attributed to several key factors. Firstly, nitrogen exhibits volatility in most of its forms, making it readily present in the gaseous state. Secondly, it is unreactive with the materials that compose the solid Earth, contributing to its stability in the atmosphere. This stability is further emphasized by its resilience in the presence of solar radiation.
A crucial point of comparison is made with oxygen, the next most abundant element in the atmosphere. Nitrogen surpasses oxygen in atmospheric abundance, being four times more prevalent. However, when considering the overall composition of the Earth, oxygen is approximately 10,000 times more abundant. This stark difference is tied to the original formation of the Earth and the accretion process.
Oxygen plays a significant role as a major component of the solid Earth, alongside elements like silicon, magnesium, calcium, and sodium. In contrast, nitrogen is not stable as part of a crystal lattice, preventing its incorporation into the solid Earth. This lack of stability in the solid Earth and the atmospheric stability of nitrogen contribute to its enrichment in the atmosphere relative to oxygen.
Unlike oxygen, nitrogen remains stable in the atmosphere and is less involved in chemical reactions that occur there. Over geological time, this stability has led to the gradual buildup of nitrogen in the atmosphere, surpassing oxygen in abundance. Both nitrogen and oxygen are integral to the planet's life cycle, playing roles in the biosphere, fossil organic matter, and sea water solubility.
It's important to note that despite their vital roles in the planet's life processes, only a small fraction of nitrogen and oxygen—less than 1% for nitrogen and much less than 1% for oxygen—is found in living biospheres, fossil organic matter, and sea water. This insightful information comes from Dr. Ken Rubin, an Assistant Professor in the Department of Geology and Geophysics at the University of Hawaii.
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