Editing Nitrogen cycle (section)

=== Other processes ===
Though nitrogen fixation is the primary source of plant-available nitrogen in most [[ecosystem]]s, in areas with nitrogen-rich [[bedrock]], the breakdown of this rock also serves as a nitrogen source.<ref name="NPR 2011" /><ref name="Schuur 2011" /><ref name="Morford 2011" /> Nitrate reduction is also part of the [[iron cycle]], under anoxic conditions Fe(II) can donate an electron to {{chem2|NO3-}} and is oxidized to Fe(III) while {{chem2|NO3-}} is reduced to {{chem2|NO2-, N2O, N2}}, and {{chem2|NH4+}} depending on the conditions and microbial species involved.<ref name="Burgin 2011" /> The [[Whale feces|fecal plumes of cetaceans]] also act as a junction in the marine nitrogen cycle, concentrating nitrogen in the epipelagic zones of ocean environments before its dispersion through various marine layers, ultimately enhancing oceanic primary productivity.<ref name="roman2010">{{cite journal | title = The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin | last1 = Roman | first1 = J. | last2 = McCarthy | first2 = J.J. | journal = PLOS ONE | volume = 5 | issue = 10 | page = e13255 |  pmc=2952594| doi = 10.1371/journal.pone.0013255 | date = 2010| pmid = 20949007 | bibcode = 2010PLoSO...513255R | doi-access = free }}</ref>