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Reduced iron associated with secondary nitrite maxima in the Arabian Sea

DRS at CSIR-National Institute of Oceanography

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Title Reduced iron associated with secondary nitrite maxima in the Arabian Sea
 
Creator Moffetta, J.W.
Goepferta, T.J.
Naqvi, S.W.A.
 
Subject dissolved organic matter
oxygen minimum layer
iron
nitrites
redox reactions
 
Description Dissolved iron and Fe(II) were measured in the oxygen minimum zone (OMZ) of the Arabian Sea in September 2004. The OMZ is a well-demarcated feature characterized by high rates of denitrification, and a deep nitrite maximum coinciding with oxygen levels below 1 mu mol L sup(-1). This zone is significantly enriched in dissolved Fe relative to overlying and underlying waters and up to 50% of the dissolved Fe is present as Fe(II). The maxima in Fe(II) are at the same depth as the deep nitrite maxima, centered around 200-250 m. They coincide with a local maximum in total dissolved Fe, suggesting that Fe accumulates at this depth because of the greater solubility of Fe(II) over Fe(III). Fe(II) is thermodynamically unstable even at submicromolar oxygen levels, so active biological reduction is the most plausible source. To our knowledge, this is the first report of a potential link between Fe reduction, elevated dissolved Fe concentrations, and nitrite accumulation within an OMZ. Denitrification has a high Fe requirement associated with the metalloenzymes for nitrate and nitrite reduction, so in situ redox cycling of Fe has important implications for the nitrogen cycle.
 
Date 2008-01-30T12:41:28Z
2008-01-30T12:41:28Z
2007
 
Type Journal Article
 
Identifier Deep-Sea Research I, Vol.54; 1341-1349p.
http://drs.nio.org/drs/handle/2264/669
 
Language en
 
Publisher Elsevier