ORCID Profile
0000-0001-6861-2490
Current Organisations
Institute for Plasma Research
,
Indian Institute of Technology Madras
,
University of St Andrews
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Publisher: Springer Science and Business Media LLC
Date: 23-09-2012
DOI: 10.1038/NGEO1585
Publisher: Wiley
Date: 26-11-2019
DOI: 10.1111/GBI.12374
Abstract: Molecular nitrogen (N
Publisher: Elsevier BV
Date: 02-2015
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 2020
Publisher: Geological Society of America
Date: 03-2015
DOI: 10.1130/G36218.1
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 09-2015
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 10-2018
Publisher: Springer Science and Business Media LLC
Date: 16-02-2015
DOI: 10.1038/NATURE14180
Abstract: 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 lightning discharge could have converted atmospheric N2 into assimilable NH4(+), HCN, or NOx species, collectively termed fixed nitrogen. But these sources may have been small on the early Earth, severely limiting the size of the primordial biosphere. The evolution of the nitrogen-fixing enzyme nitrogenase, which reduces atmospheric N2 to organic NH4(+), thus represented a major breakthrough in the radiation of life, but its timing is uncertain. Here we present nitrogen isotope ratios with a mean of 0.0 ± 1.2‰ from marine and fluvial sedimentary rocks of prehnite-pumpellyite to greenschist metamorphic grade between 3.2 and 2.75 billion years ago. These data cannot readily be explained by abiotic processes and therefore suggest biological nitrogen fixation, most probably using molybdenum-based nitrogenase as opposed to other variants that impart significant negative fractionations. Our data place a minimum age constraint of 3.2 billion years on the origin of biological nitrogen fixation and suggest that molybdenum was bioavailable in the mid-Archaean ocean long before the Great Oxidation Event.
Publisher: Proceedings of the National Academy of Sciences
Date: 20-03-2019
Abstract: Episodic development of “oxygen oases” during the Archean Eon characterizes the hundreds of millions of years transition to permanent oxygenation in the atmosphere–hydrosphere system at the Great Oxidation Event (∼2.4–2.3 Ga). One of these well-characterized oxygen oases is recorded in Mesoarchean sediments of the Pongola Supergroup. We show that in contrast to the Neoarchean, biological oxygen production in a shallow ocean having Mo-based nitrogen fixation was not sufficient to result in a dissolved nitrogen reservoir that would carry the isotopic effects of an aerobic nitrogen cycle. Nevertheless, it appears that low concentrations of bioavailable phosphorus, rather than nitrogen, suppressed the growth and expansion of oxygenic photosynthesizers and may explain why pervasive and permanent oxygenation was delayed during the Archean Eon.
Publisher: IOP Publishing
Date: 20-06-2015
Publisher: Wiley
Date: 18-06-2021
DOI: 10.1111/GBI.12459
Abstract: Due to their potential to support chemolithotrophic life, relic hydrothermal systems on Mars are a key target for astrobiological exploration. We analysed water and sediments at six geothermal pools from the rhyolitic Kerlingarfjöll and basaltic Kverkfjöll volcanoes in Iceland, to investigate the localised controls on the habitability of these systems in terms of microbial community function. Our results show that host lithology plays a minor role in pool geochemistry and authigenic mineralogy, with the system geochemistry primarily controlled by deep volcanic processes. We find that by dictating pool water pH and redox conditions, deep volcanic processes are the primary control on microbial community structure and function, with water input from the proximal glacier acting as a secondary control by regulating pool temperatures. Kerlingarfjöll pools have reduced, circum‐neutral CO 2 ‐rich waters with authigenic calcite‐, pyrite‐ and kaolinite‐bearing sediments. The dominant metabolisms inferred from community profiles obtained by 16S rRNA gene sequencing are methanogenesis, respiration of sulphate and sulphur (S 0 ) oxidation. In contrast, Kverkfjöll pools have oxidised, acidic (pH 3) waters with high concentrations of SO 4 2‐ and high argillic alteration, resulting in Al‐phyllosilicate‐rich sediments. The prevailing metabolisms here are iron oxidation, sulphur oxidation and nitrification. Where analogous ice‐fed hydrothermal systems existed on early Mars, similar volcanic processes would likely have controlled localised metabolic potential and thus habitability. Moreover, such systems offer several habitability advantages, including a localised source of metabolic redox pairs for chemolithotrophic microorganisms and accessible trace metals. Similar pools could have provided transient environments for life on Mars when paired with surface or near‐surface ice, these habitability niches could have persisted into the Amazonian. Additionally, they offer a confined site for biosignature formation and deposition that lends itself well to in situ robotic exploration.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Geological Society of London
Date: 07-07-2021
DOI: 10.1144/JGS2020-222
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-04-2023
Abstract: Many lines of inorganic geochemical evidence suggest transient “whiffs” of environmental oxygenation before the Great Oxidation Event (GOE). Slotznick et al. assert that analyses of paleoredox proxies in the Mount McRae Shale, Western Australia, were misinterpreted and hence that environmental O 2 levels were persistently negligible before the GOE. We find these arguments logically flawed and factually incomplete.
Publisher: Elsevier BV
Date: 08-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3JA50186H
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Eva Stueeken.