Modern Terrestrial Sedimentary Biostructures and Their Fossil Analogs in Mesoproterozoic Subaerial Deposits

Beraldi-Campesi, Hugo; Farmer, Jack D.; García-Pichel, Ferrán

doi:10.2110/palo.2013.084

Cited by 34 publications

(18 citation statements)

References 56 publications

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“…() extended upward to higher N 2 O fluxes and downward to lower atmospheric O 2 levels. As a conservative estimate, the ocean was assumed to be the sole source of N 2 O to the atmosphere, although there may have been active terrestrial nitrogen cycling as an additional source of N 2 O (Beraldi‐Campesi, Farmer, & Garcia‐Pichel, ; Beraldi‐Campesi & Garcia‐Pichel, ; Mancinelli & Mckay, ).…”

Section: Resultsmentioning

confidence: 99%

Nitrous oxide from chemodenitrification: A possible missing link in the Proterozoic greenhouse and the evolution of aerobic respiration

et al. 2018

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The potent greenhouse gas nitrous oxide (N O) may have been an important constituent of Earth's atmosphere during Proterozoic (~2.5-0.5 Ga). Here, we tested the hypothesis that chemodenitrification, the rapid reduction of nitric oxide by ferrous iron, would have enhanced the flux of N O from ferruginous Proterozoic seas. We empirically derived a rate law, d N 2 O d t = 7.2 × 10 - 5 [ Fe 2 + ] 0.3 [ NO ] 1 , and measured an isotopic site preference of +16‰ for the reaction. Using this empirical rate law, and integrating across an oceanwide oxycline, we found that low nM NO and μM-low mM Fe concentrations could have sustained a sea-air flux of 100-200 Tg N O-N year , if N fixation rates were near-modern and all fixed N was emitted as N O. A 1D photochemical model was used to obtain steady-state atmospheric N O concentrations as a function of sea-air N O flux across the wide range of possible pO values (0.001-1 PAL). At 100-200 Tg N O-N year and >0.1 PAL O , this model yielded low-ppmv N O, which would produce several degrees of greenhouse warming at 1.6 ppmv CH and 320 ppmv CO . These results suggest that enhanced N O production in ferruginous seawater via a previously unconsidered chemodenitrification pathway may have helped to fill a Proterozoic "greenhouse gap," reconciling an ice-free Mesoproterozoic Earth with a less luminous early Sun. A particularly notable result was that high N O fluxes at intermediate O concentrations (0.01-0.1 PAL) would have enhanced ozone screening of solar UV radiation. Due to rapid photolysis in the absence of an ozone shield, N O is unlikely to have been an important greenhouse gas if Mesoproterozoic O was 0.001 PAL. At low O , N O might have played a more important role as life's primary terminal electron acceptor during the transition from an anoxic to oxic surface Earth, and correspondingly, from anaerobic to aerobic metabolisms.

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Section: Resultsmentioning

confidence: 99%

Nitrous oxide from chemodenitrification: A possible missing link in the Proterozoic greenhouse and the evolution of aerobic respiration

et al. 2018

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“…In part this is because Precambrian and early Palaeozoic alluvial strata only rarely preserve fossil evidence for the presence of microbial mats during deposition (Schieber, 1999;Noffke et al, 2001; Davies and Gibling, 2010;Davies et al, 2011Davies et al, , 2016. Our survey of pre-vegetation fluvial units includes only 9 formations which simultaneously host evidence for microbial life (Prave, 2002;Parizot et al, 2005;Yeo et al, 2007;Rasmussen et al, 2009;Sheldon, 2012;Beraldi-Campesi et al, 2014;Wilmeth et al, 2014;Petrov, 2014Petrov, , 2015. Even fewer studies have directly used sedimentary geological evidence to support assertions of how these ancient mats may have influenced fluvial processes.…”

Section: Biotic Influences On Pre-vegetation River Systemsmentioning

confidence: 99%

Negligible microbial matground influence on pre-vegetation river functioning: Evidence from the Ediacaran-Lower Cambrian Series Rouge, France

McMahon

Davies

Went³

2017

Precambrian Research

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“…Biocrusts are thought to have played an important role in shaping the Earth's terrestrial environments since the precambrian (Beraldi-Campesi and Garcia-Pichel, 2011;Beraldi-Campesi et al, 2014;Zhao et al, 2018). Mergelov et al (2018) recently showed that the alteration of rocks by endolithic microbial communities is one likely pathway for the beginning of soils on Earth, and that the mechanisms of weathering and organic matter stabilization are strikingly similar to what can be observed in biocrusts nowadays.…”

Section: Introductionmentioning

confidence: 96%

In Situ X-Ray Tomography Imaging of Soil Water and Cyanobacteria From Biological Soil Crusts Undergoing Desiccation

Couradeau

Felde

Parkinson

et al. 2018

Front. Environ. Sci.

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Biological soil crusts (biocrusts) are millimeter-sized microbial communities developing on the topsoils of arid lands that cover some 12% of Earth's continental area. Biocrusts consist of an assemblage of mineral soil particles consolidated into a crust by microbial organic polymeric substances that are mainly produced by filamentous bundle-forming cyanobacteria, among which Microcoleus vaginatus is perhaps the most widespread. This cyanobacterium is the primary producer for, and main architect of biocrusts in many arid soils, sustaining the development of a diverse microbial community. Biocrusts are only active when wet, and spend most of their time in a state of desiccated quiescence, from which they can quickly recover upon wetting. Despite their ecological importance for arid ecosystems, little is known about the mechanisms that allow biocrust organisms to endure long periods of dryness while remaining viable for rapid resuscitation upon wetting. We had previously observed the persistence of significant rates of light-dependent carbon fixation in apparently dry biocrusts dominated by M. vaginatus, indicating that it may be able to remain hydrated against a background soil of very low water potential. One potential explanation for this may be that the abundant exopolysaccharide sheaths of M. vaginatus can preferentially retain moisture thus slowing the water equilibration with the surrounding soil allowing for extended activity periods. In order to test this hypothesis we aimed to develop methodologies to visualize and quantify the water dynamics within an undisturbed biocrust undergoing desiccation. We used synchrotron based X-ray microtomography and were able to resolve the distribution of air, liquid water, mineral particles and cyanobacterial bundles at the microscale. We could demonstrate the formation of steep, decreasing gradients of water content from the cyanobacterial bundle surface outward, while the bundle volume remained stable, as the local bulk water content decreased linearly, hence demonstrating a preferential retention of water in the microbes. Our data also suggest a transfer of hydration water from the EPS sheath material into the cyanobacterial filament as Couradeau et al. X-Ray Microtomography of a Biocrust Undergoing Desiccation desiccation progresses. This work demonstrates the value of X-ray tomography as a tool to study microbe-scale water redistribution in biocrusts.

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Modern Terrestrial Sedimentary Biostructures and Their Fossil Analogs in Mesoproterozoic Subaerial Deposits

Cited by 34 publications

References 56 publications

Nitrous oxide from chemodenitrification: A possible missing link in the Proterozoic greenhouse and the evolution of aerobic respiration

Nitrous oxide from chemodenitrification: A possible missing link in the Proterozoic greenhouse and the evolution of aerobic respiration

Negligible microbial matground influence on pre-vegetation river functioning: Evidence from the Ediacaran-Lower Cambrian Series Rouge, France

In Situ X-Ray Tomography Imaging of Soil Water and Cyanobacteria From Biological Soil Crusts Undergoing Desiccation

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