Publication Date:
2014-09-12
Description:
A quantitative understanding of sources and sinks of fixed nitrogen in low-oxygen waters is required to explain the role of oxygen-minimum zones (OMZs) in controlling the fixed nitrogen inventory of the global ocean. Apparent imbalances in geochemical nitrogen budgets have spurred numerous studies to measure the contributions of heterotrophic and autotrophic N2-producing metabolisms (denitrification and anaerobic ammonia oxidation, respectively). Recently, 'cryptic' sulphur cycling was proposed as a partial solution to the fundamental biogeochemical problem of closing marine fixed-nitrogen budgets in intensely oxygen-deficient regions. The degree to which the cryptic sulphur cycle can fuel a loss of fixed nitrogen in the modern ocean requires the quantification of sulphur recycling in OMZ settings. Here we provide a new constraint for OMZ sulphate reduction based on isotopic profiles of oxygen ((18)O/(16)O) and sulphur ((33)S/(32)S, (34)S/(32)S) in seawater sulphate through oxygenated open-ocean and OMZ-bearing water columns. When coupled with observations and models of sulphate isotope dynamics and data-constrained model estimates of OMZ water-mass residence time, we find that previous estimates for sulphur-driven remineralization and loss of fixed nitrogen from the oceans are near the upper limit for what is possible given in situ sulphate isotope data.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnston, D T -- Gill, B C -- Masterson, A -- Beirne, E -- Casciotti, K L -- Knapp, A N -- Berelson, W -- England -- Nature. 2014 Sep 25;513(7519):530-3. doi: 10.1038/nature13698. Epub 2014 Sep 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. ; Department of Geosciences, Virginia Tech University, Blacksburg, Virginia 24061, USA. ; Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA. ; Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, Florida 32306, USA. ; Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25209667" target="_blank"〉PubMed〈/a〉
Keywords:
Ammonia/metabolism
;
Anaerobiosis
;
Aquatic Organisms/metabolism
;
Nitrogen/metabolism
;
Nitrogen Fixation
;
Oxidation-Reduction
;
Oxygen/analysis/metabolism
;
Oxygen Isotopes
;
Seawater/*chemistry
;
Sulfur/*analysis/chemistry/metabolism
;
Sulfur Isotopes
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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