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Nitrous oxide (N₂O) 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 N₂O outside the well-known oxygen minimum zones (OMZ). Here we show the presence of functional marker genes for the reduction of N₂O in the last step of the denitrification process (nitrous oxide reductase genes; nosZ) in oxygenated surface waters (180–250 O₂ μmol.kg^-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 N₂O 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 N₂O, but the latter also a source of bioavailable N losses) in the understudied yet strategic Indian Ocean and other oligotrophic systems.

Item Type:	Refereed Article
Keywords:	nitrous oxide, greenhouse gas, reduction, Indian Ocean, ozone depletion, nosZ
Research Division:	Earth Sciences
Research Group:	Climate change science
Research Field:	Climate change processes
Objective Division:	Environmental Policy, Climate Change and Natural Hazards
Objective Group:	Mitigation of climate change
Objective Field:	Climate change mitigation strategies
UTAS Author:	Bodrossy, L (Dr Levente Bodrossy)
ID Code:	117108
Year Published:	2016
Web of Science® Times Cited:	13
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2017-05-31
Last Modified:	2017-07-27
Downloads:	130 View Download Statistics