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Ammonium availability in the Late Archaean nitrogen cycle

Yang, J; Junium, CK; Grassineau, NV; Nisbet, EG; Izon, G; Mettam, C; Martin, A; (2019) Ammonium availability in the Late Archaean nitrogen cycle. Nature Geoscience , 12 (7) pp. 553-557. 10.1038/s41561-019-0371-1. Green open access

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Abstract

The bioavailability of essential nutrients such as nitrogen and phosphorus has fluctuated with the chemical evolution of Earth surface environments over geological timescales. However, significant uncertainty remains over the evolution of Earth’s early nitrogen cycle, particularly how and when it responded to the evolution of oxygenic photosynthesis. Here we apply multi-proxy geochemical analyses (Fe speciation, δ13C and δ15N) to exceptionally well-preserved shales from the approximately 2.7 billion year old Manjeri Formation in the Belingwe Greenstone Belt, Zimbabwe, to evaluate the redox status of Earth’s early nitrogen cycle and decipher feedbacks associated with the initial stages of planetary oxygenation. These continental shelf sediments were previously linked to early cyanobacterial oxygen production, and provide a direct test of conflicting hypotheses concerning the importance of nitrogen oxyanions in the Late Archaean era. Our data reveal a dominantly anaerobic marine nitrogen cycle in which ammonium-replete ferruginous waters underlay an ephemeral oxygen oasis. Driven by the emergence of oxygenic photosynthesis, increased primary productivity could have periodically strengthened export production, which allowed for the accumulation of ammonium in the water column during organic matter degradation. Restricted oxygen availability could have allowed the upwelling ammonium to reach the photic zone to provide ample nitrogen to fuel a prolific Late Archaean biosphere.

Type: Article
Title: Ammonium availability in the Late Archaean nitrogen cycle
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/s41561-019-0371-1
Publisher version: https://doi.org/10.1038/s41561-019-0371-1
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Biogeochemistry, Planetary science, Precambrian geology
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10079955
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