编辑“︁氮”︁（章节）

=== 同位素 ===
{{main|氮的同位素}}
已发现的氮的[[同位素]]共有十七种，包括<chem>^10N</chem>至<chem>^25N</chem>，其中只有<chem>^14N</chem>和<chem>^15N</chem>是最稳定的。最常见的是<chem>^14N</chem>（99.634%），是在[[恒星]]的[[碳氮氧循環]]过程中产生的。<ref name="BetheBible">{{cite journal
 |last=Bethe |first=H. A.
 |year=1939
 |title=Energy Production in Stars
 |url=https://archive.org/details/sim_physical-review_1939-03-01_55_5/page/n9 |journal=[[Physical Review]]
 |volume=55 |issue=5 |pages=434–56
 |bibcode=1939PhRv...55..434B
 |doi= 10.1103/PhysRev.55.434
}}</ref>在其他人工合成的同位素中，<chem>^13N</chem>的半衰期是10分钟，其他的同位素的半衰期都是以秒计或更短。<ref name="NUBASE">{{cite journal|author=Audi, G.; Wapstra, A. H.; Thibault, C.; Blachot, J. and Bersillon, O. |year=2003 |title=The NUBASE evaluation of nuclear and decay properties |url=http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf |journal=[[Nuclear Physics A]] |volume=729 |issue= |pages=3–128 |doi=10.1016/j.nuclphysa.2003.11.001 |bibcode=2003NuPhA.729....3A |deadurl=yes |archiveurl=https://web.archive.org/web/20080923135135/http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf |archivedate=2008-09-23 }}</ref>

生物介导反应（例如[[同化 (生物学)|同化]]，[[硝化反应]]和[[反硝化反应]]）牢牢地控制着土壤的氮动力学。这些反应一般会导致基质的<chem>^15N</chem>富集和产物的<chem>^15N</chem>消耗。<ref name="enrich">{{cite book | url = http://books.google.de/books?id=U9y3whFC2DIC&pg=PA74 | pages = 74–75 | title = Stable Isotopes and Biosphere - Atmosphere Interactions: Processes and Biological Controls | isbn = 9780080525280 | author1 = Flanagan | first1 = Lawrence B. | last2 = Ehleringer | first2 = James R | last3 = Pataki | first3 = Diane E. | date = 2004-12-15 | access-date = 2013-10-02 | archive-date = 2017-01-09 | archive-url = https://web.archive.org/web/20170109022507/https://books.google.de/books?id=U9y3whFC2DIC&pg=PA74 | dead-url = no }}</ref>

地球大气中的氮气的一小部分（0.73%）是{{Link-en|同位素体|isotopologue}}<chem>^14N</chem><chem>^15N</chem>，其余的大部分是<chem>^14N2</chem>。<ref>{{cite web | url = http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=N | title = Atomic Weights and Isotopic Compositions for Nitrogen | publisher = NIST | accessdate = 2013-05-22 | archive-date = 2013-03-02 | archive-url = https://web.archive.org/web/20130302103202/http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=N | dead-url = no }}</ref>