Reduction of the Powerful Greenhouse Gas N.sub.2O in the South-Eastern Indian Ocean

Nitrous oxide (N.sub.2 O) is a powerful greenhouse gas and a key catalyst of stratospheric ozone depletion. Yet, little data exist about the sink and source terms of the production and reduction of N.sub.2 O outside the well-known oxygen minimum zones (OMZ). Here we show the presence of functional m...

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Bibliographic Details
Published in:PloS one 2016-01, Vol.11 (1)
Main Authors: Raes, Eric J, Bodrossy, Levente, Van de Kamp, Jodie, Holmes, Bronwyn, Hardman-Mountford, Nick, Thompson, Peter A, McInnes, Allison S, Waite, Anya M
Format: Article
Language:English
Subjects:
Air pollution
Nitrification
Ozone layer depletion
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Summary:Nitrous oxide (N.sub.2 O) is a powerful greenhouse gas and a key catalyst of stratospheric ozone depletion. Yet, little data exist about the sink and source terms of the production and reduction of N.sub.2 O outside the well-known oxygen minimum zones (OMZ). Here we show the presence of functional marker genes for the reduction of N.sub.2 O in the last step of the denitrification process (nitrous oxide reductase genes; nosZ) in oxygenated surface waters (180-250 O.sub.2 [mu]mol.kg.sup.-1) in the south-eastern Indian Ocean. Overall copy numbers indicated that nosZ genes represented a significant proportion of the microbial community, which is unexpected in these oxygenated waters. Our data show strong temperature sensitivity for nosZ genes and reaction rates along a vast latitudinal gradient (32°S-12°S). These data suggest a large N.sub.2 O sink in the warmer Tropical waters of the south-eastern Indian Ocean. Clone sequencing from PCR products revealed that most denitrification genes belonged to Rhodobacteraceae. Our work highlights the need to investigate the feedback and tight linkages between nitrification and denitrification (both sources of N.sub.2 O, but the latter also a source of bioavailable N losses) in the understudied yet strategic Indian Ocean and other oligotrophic systems.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0145996