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Nitrogen in rock: Occurrences and biogeochemical implications
Author(s) -
Holloway JoAnn M.,
Dahlgren Randy A.
Publication year - 2002
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2002gb001862
Subject(s) - nitrogen cycle , biogeochemical cycle , reactive nitrogen , nitrogen , environmental chemistry , bedrock , ecosystem , environmental science , weathering , nitrate , leaching (pedology) , nutrient cycle , geology , soil water , soil science , ecology , chemistry , geochemistry , geomorphology , organic chemistry , biology
There is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations. Nitrogen‐bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification. Nitrogen in rock originates as organically bound nitrogen associated with sediment, or in thermal waters representing a mixture of sedimentary, mantle, and meteoric sources of nitrogen. Rock nitrogen concentrations range from trace levels (<200 mg N kg −1 ) in granites to ecologically significant concentrations exceeding 1000 mg N kg −1 in some sedimentary and metasedimentary rocks. Nitrate deposits accumulated in arid and semi‐arid regions are also a large potential pool. Nitrogen in rock has a potentially significant impact on localized nitrogen cycles. Elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen. In some environments, nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems (more nitrogen available than required by biota). Nitrogen saturation results in leaching of nitrate to surface and groundwaters, and, where soils are formed from ammonium‐rich bedrock, the oxidation of ammonium to nitrate may result in soil acidification, inhibiting revegetation in certain ecosystems. Collectively, studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems.