Stabilization of the coupled oxygen and phosphorus cycles by the evolution of bioturbation.

Boyle, Richard, Dahl, Tais, Dale, Andrew W. , Shields, Graham, Zhu, Mao-yan, Brasier, Martin, Canfield, Donald and Lenton, Timothy (2014) Stabilization of the coupled oxygen and phosphorus cycles by the evolution of bioturbation. Nature Geoscience, 7 (9). pp. 671-676. DOI 10.1038/ngeo2213.

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Abstract

Animal burrowing and sediment-mixing (bioturbation) began during the run up to the Ediacaran/Cambrian boundary1, 2, 3, initiating a transition4, 5 between the stratified Precambrian6 and more well-mixed Phanerozoic7 sedimentary records, against the backdrop of a variable8, 9 global oxygen reservoir probably smaller in size than present10, 11. Phosphorus is the long-term12 limiting nutrient for oxygen production via burial of organic carbon13, and its retention (relative to carbon) within organic matter in marine sediments is enhanced by bioturbation14, 15, 16, 17, 18. Here we explore the biogeochemical implications of a bioturbation-induced organic phosphorus sink in a simple model. We show that increased bioturbation robustly triggers a net decrease in the size of the global oxygen reservoir—the magnitude of which is contingent upon the prescribed difference in carbon to phosphorus ratios between bioturbated and laminated sediments. Bioturbation also reduces steady-state marine phosphate levels, but this effect is offset by the decline in iron-adsorbed phosphate burial that results from a decrease in oxygen concentrations. The introduction of oxygen-sensitive bioturbation to dynamical model runs is sufficient to trigger a negative feedback loop: the intensity of bioturbation is limited by the oxygen decrease it initially causes. The onset of this feedback is consistent with redox variations observed during the early Cambrian rise of bioturbation, leading us to suggest that bioturbation helped to regulate early oxygen and phosphorus cycles.

Document Type: Article
Additional Information: WOS:000341635600017
Keywords: ATMOSPHERIC OXYGEN; ORGANIC-CARBON; OCEAN; BURIAL; REGENERATION; FLUCTUATIONS; ICHNOFABRICS; SEDIMENTS; TRENDS; ANOXIA
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > SFB 754 > B1
OceanRep > SFB 754
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1038/ngeo2213
ISSN: 1752-0894
Projects: SFB754
Date Deposited: 11 Aug 2014 10:30
Last Modified: 20 Feb 2017 14:02
URI: http://oceanrep.geomar.de/id/eprint/25424

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