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Marine nitrogen fixers mediate a low latitude pathway for atmospheric CO2 drawdown


Buchanan, PJ and Chase, Z and Matear, RJ and Phipps, SJ and Bindoff, NL, Marine nitrogen fixers mediate a low latitude pathway for atmospheric CO2 drawdown, Nature Communications, 10, (1) Article 4611. ISSN 2041-1723 (2019) [Refereed Article]


Copyright Statement

Copyright 2019 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

DOI: doi:10.1038/s41467-019-12549-z


Roughly a third (~30 ppm) of the carbon dioxide (CO2) that entered the ocean during ice ages is attributed to biological mechanisms. A leading hypothesis for the biological drawdown of CO2 is iron (Fe) fertilisation of the high latitudes, but modelling efforts attribute at most 10 ppm to this mechanism, leaving ~20 ppm unexplained. We show that an Fe-induced stimulation of dinitrogen (N2) fixation can induce a low latitude drawdown of 716 ppm CO2. This mechanism involves a closer coupling between N2 fixers and denitrifiers that alleviates widespread nitrate limitation. Consequently, phosphate utilisation and carbon export increase near upwelling zones, causing deoxygenation and deeper carbon injection. Furthermore, this low latitude mechanism reproduces the regional patterns of organic δ15N deposited in glacial sediments. The positive response of marine N2 fixation to dusty ice age conditions, first proposed twenty years ago, therefore compliments high latitude changes to amplify CO2 drawdown.

Item Details

Item Type:Refereed Article
Keywords:carbon dioxide, ocean, ice ages, iron, nitrogen
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Management
Objective Group:Air quality, atmosphere and weather
Objective Field:Atmospheric composition (incl. greenhouse gas inventory)
UTAS Author:Buchanan, PJ (Mr Pearse Buchanan)
UTAS Author:Chase, Z (Professor Zanna Chase)
UTAS Author:Phipps, SJ (Dr Steven Phipps)
UTAS Author:Bindoff, NL (Professor Nathan Bindoff)
ID Code:135342
Year Published:2019
Web of Science® Times Cited:6
Deposited By:Geography and Spatial Science
Deposited On:2019-10-14
Last Modified:2020-05-19
Downloads:5 View Download Statistics

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