Publication Date:
2009-02-21
Description:
The nitrogen cycle provides essential nutrients to the biosphere, but its antiquity in modern form is unclear. In a drill core though homogeneous organic-rich shale in the 2.5-billion-year-old Mount McRae Shale, Australia, nitrogen isotope values vary from +1.0 to +7.5 per mil (per thousand) and back to +2.5 per thousand over approximately 30 meters. These changes evidently record a transient departure from a largely anaerobic to an aerobic nitrogen cycle complete with nitrification and denitrification. Complementary molybdenum abundance and sulfur isotopic values suggest that nitrification occurred in response to a small increase in surface-ocean oxygenation. These data imply that nitrifying and denitrifying microbes had already evolved by the late Archean and were present before oxygen first began to accumulate in the atmosphere.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Garvin, Jessica -- Buick, Roger -- Anbar, Ariel D -- Arnold, Gail L -- Kaufman, Alan J -- New York, N.Y. -- Science. 2009 Feb 20;323(5917):1045-8. doi: 10.1126/science.1165675.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Space Sciences and Astrobiology Program, University of Washington, Seattle, WA 98195-1310, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19229033" target="_blank"〉PubMed〈/a〉
Keywords:
Aerobiosis
;
Anaerobiosis
;
Archaea/*metabolism
;
Australia
;
Bacteria/*metabolism
;
Biological Evolution
;
Geologic Sediments/*chemistry
;
Nitrates/chemistry/metabolism
;
Nitrites/chemistry/metabolism
;
Nitrogen/*chemistry/*metabolism
;
Nitrogen Fixation
;
Nitrogen Isotopes/*analysis
;
Oceans and Seas
;
Oxidation-Reduction
;
Oxygen/*chemistry/metabolism
;
Quaternary Ammonium Compounds/chemistry/metabolism
;
Time
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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