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Isotopic evidence for biological nitrogen fixation by molybdenum-nitrogenase from 3.2 Gyr
Nitrogen is an essential nutrient for all organisms that must have been available since the origin of life. Abiotic processes including hydrothermal reduction, photochemical reactions, or lightningExpand
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Contributions to late Archaean sulphur cycling by life on land
Life on land dates back at least 2.7 billion years, but the effects of this early terrestrial biosphere on biogeochemical cycling are poorly constrained. Marine sulphur data and geochemical modellingExpand
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Nitrogen isotope evidence for alkaline lakes on late Archean continents
Abstract Nitrogen isotope ratios in ancient sedimentary rocks are generally interpreted as a proxy for metabolic nitrogen pathways and the redox state of the water column. Fractionation processesExpand
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Modeling the signature of sulfur mass-independent fractionation produced in the Archean atmosphere
Minor sulfur isotope anomalies indicate the absence of O2 from the Archean atmosphere. A rich dataset showing large variations in magnitude and sign of Δ33S and Δ36S, preserved in both sulfates andExpand
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Modeling pN2 through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures.
Nitrogen is a major nutrient for all life on Earth and could plausibly play a similar role in extraterrestrial biospheres. The major reservoir of nitrogen at Earth's surface is atmospheric N2, butExpand
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The evolution of Earth's biogeochemical nitrogen cycle
Financial support during the compilation of this manuscript was provided by the NASA postdoctoral program (EES), the NSF Graduate Research Fellowship Program (MAK), the Agouron Institute (MCK, RB)Expand
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A test of the nitrogen-limitation hypothesis for retarded eukaryote radiation: Nitrogen isotopes across a Mesoproterozoic basinal profile
Abstract Nitrogen limitation caused by trace metal scarcity under euxinic ocean conditions has been proposed as an explanation for the delayed radiation of eukaryotes until at least the lateExpand
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Selenium isotopes support free O2 in the latest Archean
Selenium (Se) undergoes redox transformations and isotopic fractionations at relatively high redox potentials and could therefore provide insight into changes in oceanic and atmospheric O2 levelsExpand
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Selenium isotopes record extensive marine suboxia during the Great Oxidation Event
Significance Oxygen is essential for eukaryotic life. The geologic record of early Earth contains abundant evidence of low oxygen levels, and accordingly, a lack of eukaryote fossils. The rise ofExpand
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Biomass recycling and Earth’s early phosphorus cycle
The scarcity of oxidants in the ancient oceans may have inhibited phosphorus recycling, stifling the growth of the biosphere. Phosphorus sets the pace of marine biological productivity on geologicalExpand
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