Deep abiotic weathering of pyrite

Science ◽  
2020 ◽  
Vol 370 (6515) ◽  
pp. eabb8092
Author(s):  
Xin Gu ◽  
Peter J. Heaney ◽  
Fabio D. A. Aarão Reis ◽  
Susan L. Brantley
Keyword(s):  
Large Scale ◽  
Iron Sulfide ◽  
Atmospheric Oxygen ◽  
Pyrite Oxidation ◽  
Microscopic Analysis ◽  
Sulfide Mineral ◽  
Early Atmosphere ◽  
Sulfur Oxidizing ◽  
Pyrite Weathering ◽  
Grain Surface

Pyrite is a ubiquitous iron sulfide mineral that is oxidized by trace oxygen. The mineral has been largely absent from global sediments since the rise in oxygen concentration in Earth’s early atmosphere. We analyzed weathering in shale, the most common rock exposed at Earth’s surface, with chemical and microscopic analysis. By looking across scales from 10−9 to 102 meters, we determined the factors that control pyrite oxidation. Under the atmosphere today, pyrite oxidation is rate-limited by diffusion of oxygen to the grain surface and regulated by large-scale erosion and clast-scale fracturing. We determined that neither iron- nor sulfur-oxidizing microorganisms control global pyrite weathering fluxes despite their ability to catalyze the reaction. This multiscale picture emphasizes that fracturing and erosion are as important as atmospheric oxygen in limiting pyrite reactivity over Earth’s history.

scholarly journals Metagenomes and metatranscriptomes from boreal potential and actual acid sulfate soil materials

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Eva Högfors-Rönnholm ◽  
Margarita Lopez-Fernandez ◽  
Stephan Christel ◽  
Diego Brambilla ◽  
Marcel Huntemann ◽  
...  
Keyword(s):  
Iron Sulfide ◽  
Atmospheric Oxygen ◽  
Sulfide Mineral ◽  
Rrna Gene ◽  
Acid Sulfate Soils ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Potential Acid ◽  
The Baltic ◽  
Sulfate Soils

Abstract Natural sulfide rich deposits are common in coastal areas worldwide, including along the Baltic Sea coast. When artificial drainage exposes these deposits to atmospheric oxygen, iron sulfide minerals in the soils are rapidly oxidized. This process turns the potential acid sulfate soils into actual acid sulfate soils and mobilizes large quantities of acidity and leachable toxic metals that cause severe environmental problems. It is known that acidophilic microorganisms living in acid sulfate soils catalyze iron sulfide mineral oxidation. However, only a few studies regarding these communities have been published. In this study, we sampled the oxidized actual acid sulfate soil, the transition zone where oxidation is actively taking place, and the deepest un-oxidized potential acid sulfate soil. Nucleic acids were extracted and 16S rRNA gene amplicons, metagenomes, and metatranscriptomes generated to gain a detailed insight into the communities and their activities. The project will be of great use to microbiologists, environmental biologists, geochemists, and geologists as there is hydrological and geochemical monitoring from the site stretching back for many years.

Pyrite and the Global Environment

Pyrite ◽  
2015 ◽  
Author(s):  
David Rickard
Keyword(s):  
Iron Sulfide ◽  
Sulfide Oxidation ◽  
Sulfate Reducing Bacteria ◽  
Sulfide Mineral ◽  
Sulfur Cycle ◽  
Sulfate Reducing ◽  
Global Dynamic ◽  
Sulfur Oxidizing ◽  
Life On Earth ◽  
Reducing Bacteria

The two basic processes concerning pyrite in the environment are the formation of pyrite, which usually involves reduction of sulfate to sulfide, and the destruction of pyrite, which usually involves oxidation of sulfide to sulfate. On an ideal planet these two processes might be exactly balanced. But pyrite is buried in sediments sometimes for hundreds of millions of years, and the sulfur in this buried pyrite is removed from the system, so the balance is disturbed. The lack of balance between sulfide oxidation and sulfate reduction powers a global dynamic cycle for sulfur. This would be complex enough if this were the whole story. However, as we have seen, both the reduction and oxidation arms of the global cycle are essentially biological—specifically microbiological—processes. This means that there is an intrinsic link between the sulfur cycle and life on Earth. In this chapter, we examine the central role that pyrite plays, and has played, in determining the surface environment of the planet. In doing so we reveal how pyrite, the humble iron sulfide mineral, is a key component of maintaining and developing life on Earth. In Chapter 4 we concluded that Mother Nature must be particularly fond of pyrite framboids: a thousand billion of these microscopic raspberry-like spheres are formed in sediments every second. If we translate this into sulfur production, some 60 million tons of sulfur is buried as pyrite in sediments each year. But this is only a fraction of the total amount of sulfide produced every year by sulfate-reducing bacteria. In 1982 the Danish geomicrobiologist Bo Barker Jørgensen discovered that as much as 90% of the sulfide produced by sulfate-reducing bacteria was rapidly reoxidized by sulfur-oxidizing microorganisms. Sulfate-reducing microorganisms actually produce about 300 million tons of sulfur each year, but about 240 million tons is reoxidized. The magnitude of the sulfide production by sulfate-reducing bacte­ria can be appreciated by comparison with the sulfur produced by volcanoes. As discussed in Chapter 5, it was previously supposed that all sulfur, and thus pyrite, had a volcanic origin. In fact volcanoes produce just 10 million tons of sulfur each year.

Characterization of seawater reverse osmosis fouled membranes from large scale commercial desalination plant

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Reverse Osmosis ◽  
Large Scale ◽  
Retention Rate ◽  
Local Level ◽  
Microscopic Analysis ◽  
Transmembrane Pressure ◽  
Hydraulic Permeability ◽  
Seawater Reverse Osmosis ◽  
A Chain

The objective of this work is to study the ageing state of a used reverse osmosis (RO) membrane taken in Algeria from the Benisaf Water Company seawater desalination unit. The study consists of an autopsy procedure used to perform a chain of analyses on a membrane sheet. Wear of the membrane is characterized by a degradation of its performance due to a significant increase in hydraulic permeability (25%) and pressure drop as well as a decrease in salt retention (10% to 30%). In most cases the effects of ageing are little or poorly known at the local level and global measurements such as (flux, transmembrane pressure, permeate flow, retention rate, etc.) do not allow characterization. Therefore, a used RO (reverse osmosis) membrane was selected at the site to perform the membrane autopsy tests. These tests make it possible to analyze and identify the cause as well as to understand the links between performance degradation observed at the macroscopic scale and at the scale at which ageing takes place. External and internal visual observations allow seeing the state of degradation. Microscopic analysis of the used membranes surface shows the importance of fouling. In addition, quantification and identification analyses determine a high fouling rate in the used membrane whose foulants is of inorganic and organic nature. Moreover, the analyses proved the presence of a biofilm composed of protein.

Genetic dissection of the retinotectal projection

Development ◽  
1996 ◽  
Vol 123 (1) ◽  
pp. 415-425 ◽  
Author(s):  
H. Baier ◽  
S. Klostermann ◽  
T. Trowe ◽  
R.O. Karlstrom ◽  
C. Nusslein-Volhard ◽  
...  
Keyword(s):  
Large Scale ◽  
Fish Larvae ◽  
Microscopic Analysis ◽  
Genetic Dissection ◽  
Axon Pathfinding ◽  
Retinotectal Projection ◽  
Vertebrate Brain ◽  
Retinal Axons ◽  
Assay Procedure ◽  
Homozygous Diploid

A systematic search for mutations affecting the retinotectal projection in zebrafish larvae was performed, as part of the large-scale Tubingen screen for homozygous diploid mutants in embryonic development. 2,746 inbred lines (F2 families) from males mutagenized with ethylnitroso urea were screened. In wild-type larvae, developing retinal axons travel along a stereotyped route to the contralateral optic tectum. Here, their terminals form a highly ordered retinotopic map. To detect deviations from this pattern, an axon tracing assay was developed that permits screening of large numbers of mutagenized fish. Two fluorescent tracer dyes (DiI and DiO) were injected at opposite poles of the eyes of day-5 aldehyde-fixed larvae. 12 hours later, retinal axons were labelled over their entire length, and could be observed through the intact skin. The assay procedure (aldehyde fixation, mounting, injection of dyes, microscopic analysis) took about 1 minute per fish. In total, 125,000 individual fish larvae were processed. During the screen, 114 mutations in approx. 35 genes were discovered. For the mutants subjected to complementation testing, the number of alleles per locus ranges from 1 to 15. The mutations affect distinct steps in the retinotectal pathway, from pathfinding between eye and tectum to map formation along the dorsal-ventral and the anterior-posterior axis of the tectum. Mutations that disturb axon pathfinding to the tectum for the most part do not disrupt retinotopic mapping, and vice versa. The majority of the mutants display associated defects in other tissues and die before day 10. These mutants provide new tools for studying the formation of neuronal maps. The results of this screen show that a large-scale genetic approach can be applied to relatively late and circumscribed developmental processes in the vertebrate brain.

Reaction pathways of iron-sulfide mineral formation: an in situ X-ray diffraction study

2018 ◽  
Vol 30 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Min-Yu Lin ◽  
Yen-Hua Chen ◽  
Jey-Jau Lee ◽  
Hwo-Shuenn Sheu
Keyword(s):  
Diffraction Study ◽  
Iron Sulfide ◽  
Sulfide Mineral ◽  
Reaction Pathways ◽  
Mineral Formation ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Deciphering the role of trehalose in hindering antithrombin polymerization

2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Asma Naseem ◽  
Mohammad Sazzad Khan ◽  
Hashim Ali ◽  
Irshad Ahmad ◽  
Mohamad Aman Jairajpuri
Keyword(s):  
Conformational Change ◽  
Large Scale ◽  
Guanidine Hydrochloride ◽  
Microscopic Analysis ◽  
Normal Activity ◽  
Significant Loss ◽  
Coagulation Cascade ◽  
Disulfonic Acid ◽  
Electron Microscopic ◽  
Polymer Formation

Abstract Serine protease inhibitors (serpins) family have a complex mechanism of inhibition that requires a large scale conformational change. Antithrombin (AT), a member of serpin superfamily serves as a key regulator of the blood coagulation cascade, deficiency of which leads to thrombosis. In recent years, a handful of studies have identified small compounds that retard serpin polymerization but abrogated the normal activity. Here, we screened small molecules to find potential leads that can reduce AT polymer formation. We identified simple sugar molecules that successfully blocked polymer formation without a significant loss of normal activity of AT under specific buffer and temperature conditions. Of these, trehalose proved to be most promising as it showed a marked decrease in the bead like polymeric structures of AT shown by electron microscopic analysis. A circular dichroism (CD) analysis indicated alteration in the secondary structure profile and an increased thermal stability of AT in the presence of trehalose. Guanidine hydrochloride (GdnHCl)-based unfolding studies of AT show the formation of a different intermediate in the presence of trehalose. A time-dependent fluorescence study using 1,1′-bi(4-anilino)naphthalene-5,5′-disulfonic acid (Bis-ANS) shows that trehalose affects the initial conformational change step in transition from native to polymer state through its binding to exposed hydrophobic residues on AT thus making AT less polymerogenic. In conclusion, trehalose holds promise by acting as an initial scaffold that can be modified to design similar compounds with polymer retarding propensity.

scholarly journals Examining pathways of iron and sulfur acquisition, trafficking, deployment, and storage in mineral-grown methanogen cells

2021 ◽  
Author(s):  
Devon Payne ◽  
Eric M. Shepard ◽  
Rachel L. Spietz ◽  
Katherine Steward ◽  
Sue Brumfield ◽  
...  
Keyword(s):  
Iron Sulfide ◽  
Storage Proteins ◽  
Spectral Feature ◽  
Methanogenic Archaea ◽  
Sulfide Mineral ◽  
Methanococcus Voltae ◽  
Fe Content ◽  
And Storage ◽  
Fe Acquisition ◽  
Excess Fe

Methanogens have a high demand for iron (Fe) and sulfur (S); however, little is known of how they acquire, deploy, and store these elements and how this, in turn, affects their physiology. Methanogens were recently shown to reduce pyrite (FeS 2 ) generating aqueous iron-sulfide (FeS (aq) ) clusters that are likely assimilated as a source of Fe and S. Here, we compare the phenotype of Methanococcus voltae when grown with FeS 2 or ferrous iron (Fe(II)) and sulfide (HS - ). FeS 2 -grown cells are 33% smaller yet have 193% more Fe than Fe(II)/HS - -grown cells. Whole cell EPR revealed similar distributions of paramagnetic Fe, although FeS 2 -grown cells showed a broad spectral feature attributed to intracellular thioferrate-like nanoparticles. Differential proteomic analyses showed similar expression of core methanogenesis enzymes, indicating that Fe and S source does not substantively alter the energy metabolism of cells. However, a homolog of the Fe(II) transporter FeoB and its putative transcriptional regulator DtxR were up-expressed in FeS 2 -grown cells, suggesting that cells sense Fe(II) limitation. Two homologs of IssA, a protein putatively involved in coordinating thioferrate nanoparticles, were also up-expressed in FeS 2 -grown cells. We interpret these data to indicate that, in FeS 2 -grown cells, DtxR cannot sense Fe(II) and therefore cannot down-regulate FeoB. We suggest this is due to the transport of Fe(II) complexed with sulfide (FeS (aq) ) leading to excess Fe that is sequestered by IssA as a thioferrate-like species. This model provides a framework for the design of targeted experiments aimed at further characterizing Fe acquisition and homeostasis in M. voltae and other methanogens. IMPORTANCE FeS 2 is the most abundant sulfide mineral in the Earth’s crust and is common in environments inhabited by methanogenic archaea. FeS 2 can be reduced by methanogens, yielding aqueous FeS (aq) clusters that are thought to be a source of Fe and S. Here, we show that growth of Methanococcus voltae on FeS 2 results in smaller cell size and higher Fe content per cell, with Fe likely stored intracellularly as thioferrate-like nanoparticles. Fe(II) transporters and storage proteins were up-regulated in FeS 2 -grown cells. These responses are interpreted to result from cells incorrectly sensing Fe(II) limitation due to assimilation of Fe(II) as FeS (aq) . These findings have implications for our understanding of how Fe/S availability influences methanogen physiology and the biogeochemical cycling of these elements.

scholarly journals Contributions of Microbial “Contact Leaching” to Pyrite Oxidation under Different Controlled Redox Potentials

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 856
Author(s):  
Bingxu Dong ◽  
Yan Jia ◽  
Qiaoyi Tan ◽  
Heyun Sun ◽  
Renman Ruan
Keyword(s):  
Redox Potential ◽  
Dissolution Rate ◽  
Elemental Sulfur ◽  
Microbial Consortium ◽  
Pyrite Oxidation ◽  
Microbial Consortia ◽  
Redox Potentials ◽  
Sulfur Passivation ◽  
Sulfur Oxidizing ◽  
Contact Oxidation

The function of microbial contact leaching to pyrite oxidation was investigated by analyzing the differences of residue morphologies, leaching rates, surface products, and microbial consortia under different conditions in this study. This was achieved by novel equipment that can control the redox potential of the solution and isolate pyrite from microbial contact oxidation. The morphology of residues showed that the corrosions were a little bit severer in the presence of attached microbes under 750 mV and 850 mV (vs. SHE). At 650 mV, the oxidation of pyrite was undetectable even in the presence of attached microbes. The pyrite dissolution rate was higher with attached microbes than that without attached microbes at 750 mV and 850 mV. The elemental sulfur on the surface of pyrite residues with sessile microorganisms was much less than that without attached microbes at 750 mV and 850 mV, showing that sessile acidophiles may accelerate pyrite leaching by reducing the elemental sulfur inhibition. Many more sulfur-oxidizers were found in the sessile microbial consortium which also supported the idea. The results suggest that the microbial “contact leaching” to pyrite oxidation is limited and relies on the elimination of elemental sulfur passivation by attached sulfur-oxidizing microbes rather than the contact oxidation by EPS-Fe.

scholarly journals The Natural History of Oxygen

1965 ◽  
Vol 49 (1) ◽  
pp. 5-27 ◽  
Author(s):  
Malcolm Dole
Keyword(s):  
Nuclear Reactions ◽  
Atmospheric Oxygen ◽  
Cold Trap ◽  
Hydrogen Atoms ◽  
Absorption Bands ◽  
Free Oxygen ◽  
Early Atmosphere ◽  
History Of ◽  
Photosynthetic Oxygen ◽  
Using Data

The nuclear reactions occurring in the cores of stars which are believed to produce the element oxygen are first described. Evidence for the absence of free oxygen in the early atmosphere of the earth is reviewed. Mechanisms of creation of atmospheric oxygen by photochemical processes are then discussed in detail. Uncertainty regarding the rate of diffusion of water vapor through the cold trap at 70 km altitude in calculating the rate of the photochemical production of oxygen is avoided by using data for the concentration of hydrogen atoms at 90 km obtained from the Meinel OH absorption bands. It is estimated that the present atmospheric oxygen content could have been produced five to ten times during the earth's history. It is shown that the isotopic composition of atmospheric oxygen is not that of photosynthetic oxygen. The fractionation of oxygen isotopes by organic respiration and oxidation occurs in a direction to enhance the O18 content of the atmosphere and compensates for the O18 dilution resulting from photosynthetic oxygen. Thus, an oxygen isotope cycle exists in nature.

scholarly journals Conservative transport of dissolved sulfate across the Rio Madre de Dios floodplain in Peru

Geology ◽  
2021 ◽  
Author(s):  
Emily I. Burt ◽  
Markus Bill ◽  
Mark E. Conrad ◽  
Adan Julian Ccahuana Quispe ◽  
John N. Christensen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Stable Isotope ◽  
Carbonic Acid ◽  
Isotope Composition ◽  
Sulfide Oxidation ◽  
Pyrite Oxidation ◽  
Sulfide Mineral ◽  
Mineral Weathering ◽  
Primary Role ◽  
Peruvian Andes

Mineral weathering plays a primary role in the geologic carbon cycle. Silicate weathering by carbonic acid consumes CO2 and stabilizes Earth’s climate system. However, when sulfuric acid drives weathering, CO2 can be released to the atmosphere. Recent work has established that sulfuric acid weathering resulting from sulfide mineral oxidation is globally significant and particularly important in rapidly eroding environments. In contrast, if SO42– produced by sulfide oxidation is reduced during continental transit, then CO2 release may be negated. Yet, little is known about how much SO42– reduction takes place in terrestrial environments. We report oxygen and sulfur stable isotope ratios of SO42– in river waters and mass budget calculations, which together suggest that SO42– released from pyrite oxidation in the Peruvian Andes mountains is conservatively exported across ~300 km of the Amazon floodplain. In this system, floodplain SO42– reduction does not counteract the large SO42– flux from Andean pyrite weathering or measurably affect the stable isotope composition of riverine SO42–. These findings support the hypothesis that uplift and erosion of sedimentary rocks drive release of CO2 from the rock reservoir to the atmosphere.

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