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In mangroves, estimated global TAlk production coupled to pyrite formation (∼3 mol/m 2 /y) is equal to ∼24% of their global carbon …
Oxidation rate of microscopic pyrite with different morphologies. ... Dara, O., Gordeev, V. (2018) Framboidal pyrite formation in the bottom sediments of the South Caspian Basin under conditions of hydrogen sulfide contamination. Russian Journal of Earth Sciences 18, 1–10. Show in context.
Rickard D. T. (1975) Kinetics and mechanisms of pyrite formation at low temperatures. Am. J. Sci. 275, 636-652. Google Scholar Rickard D. (1997) Kinetics of pyrite formation by the H 2 S oxidation of iron(II) monosulfide in aqueous solutions between 25°C and 125°C: The rate equation.Geochim. Cosmochim. Acta 61, 115-134.
rates can release damaging quantities of acidity, metals, and other soluble components into the ... The conditions most conducive to acid formation are high pyrite contents with little base material present. Conversely, an excess of base relative to pyrite is most likely to preclude acid formation. Sites containing
Furthermore, it is well-known that different bacteria can catalyze the pyrite oxidation at a much rapid rate, making its mechanism even more complex. (20) Many works identified the formation of oxidative dissolution products on pyrite, and surface sensitive techniques have been carried out to understand the pyrite reactivity in the presence of ...
The onset of pyrite formation was found to significantly differ as a function of the TE added in the starting solution (Fig. 1), as revealed by powder XRD analyses of the solids collected over the course of the syntheses (Figs. 2 and SI-1–SI-10).Pyrite was detected after 235 h in the control experiment (Fe-S) and was fully formed after 330 h …
Similarly, Unit C has a sedimentation rate of ca. 17, 11 and 4 m/ka in core CM01, CM02, and HSD, respectively. Due to rapid deposition, sulphate reduction lacks sufficient time for sulfide accumulation, which can favor greigite over pyrite formation (Aben et al., 2014; Figure 9).
In hydrothermal systems, such as deep ocean vents, the rate of pyrite formation by oxidation of FeS by H2S at 125 assuming a typical HzS concentration of 1 …
For example, recent studies showed that the high sedimentation rates are conducive to the formation of the relative "closed" diagenetic system, leading to the formation of isotopically "heavy" pyrite (Pasquier et al., 2017; Liu et al., 2019). Other processes that may cause the enrichment of 34 S in pyrite are as follows.
Pyrite has completely oxidized throughout the layer of thickness L b, except in the bottom ~1-m-thick depth interval (l b) located about 1.5 to 3.5 m above the water table, where oxidation and formation of pseudomorphs are ongoing (Fig. 1A and fig. S2). We determined the change in fractional extent of oxidation versus depth across l b.
The rate of pyrite formation in the metal-AOM zone is much lower than that formed in SMTZ, consequently, the pyrite formed in the metal-AOM zone might have a relatively small size. 8. Alteration in Later Diagenetic Processes.
Here we show the rapid formation of large pyrite spherules through the sulfidation of Fe (III)-phosphate (FP) in the presence of a consortium of sulfur- and sulfate …
Collector stone Fool's Gold and Black Gold Richard P. Wells, reprinted with permission of the National Driller's Buyers Guide, July 1995 Iron pyrite, the fool's gold of antiquity, turns out to be a useful indicator for those of us …
We measured maximum rates of pyrite formation (~2.8 × 10 −6 mol of pyrite l −1 s −1) close to published data [~ 3 × 10 −6 mol of pyrite l −1 s −1 ]. The pyrite-forming process is mechanistically uniform over the 25° to 125°C temperature range ( 13 ), and the observed temperature-independent effect indicates that our results may ...
Field occurrence of pyrite nodules. The Doushantuo Formation in the South China Block directly overlies the Nantuo glacial diamictite and consists of as much as 250 m of carbonates, siltstones ...
The rate of pyrite formation in this chemically-controlled reaction is considerably greater than observed rates in natural sediments, which are probably transport-controlled. Refs.
In situ rates of pyrite formation depend on a wide range of environmental conditions (Burton et al., 2011). The availability of sulfate, organic carbon, and reactive iron are key factors controlling pyrite formation in coastal sediments (Berner, 1970, 1984; Figure 1). In blue carbon ecosystems, tidal seawater inundation resupplies the sulfate ...
To investigate how seasonal oxygen stress influences surficial (<2 cm) pyrite formation, we measured time-series concentrations and sulfur isotope ... implying that changes in the sulfur-cycling microbial community composition might influence rates of shallow pyrite formation. We also propose that rapid redistribution of sulfur isotopes in ...
Rates of pyrite formation based on the FeS 2 profiles were much lower than those predicted by applying commonly used kinetic equations ... mackinawite and greigite) to pyrite (67%–78% vs. 93%, in the presence and absence of Ni, respectively). Pyrite formation from metastable sulfide precursors yielded a uniform Ni distribution in newly …
Coupling of pyrite formation to methanogenesis has been proposed by Jørgensen and coworkers ... The carrier gas was N 2 at a flow rate of 3.2 mL⋅min −1. Chromatograms were recorded with the …
Isotopically "heavy" pyrite in marine sediments due to high sedimentation rates and non-steady-state deposition The MIT Faculty has made this article openly available. Please …
Pyrite scale formation is a critical problem in the hydrocarbon production industry; it affects the flow of hydrocarbon within the reservoir and the surface facilities. Treatments with inorganic ...
Cubes are also the most common pyrite crystal form. The rate of growth of the crystal faces is different on each face, and square prisms are more probable results than perfect cubes. In the extreme case this feature may result in the formation of pyrite wires. This explains the formation of balls of radiating pyrite crystals, commonly found in ...
Pyrite is stable at low temperature in the absence of oxygen and oxidative weathering, and its formation history can therefore be recorded back in sedimentary rocks over geological timescales [3 ...
To quantify the fraction (β) of pyrite precipitation supported by organic sulfur, we used the ratio of the depth-integrated rates of sulfide generation to iron sulfide formation, corrected for ...
Pyrite seldom forms in fresh-water environments. The formation of pyrite crystals depends mainly on the iron content of the sediment. The process of pyrite formation in sediments results from the action of bacteria, which reduce sulphate ions (dissolved in the pore water) to sulphide. If there is iron present, iron sulphide crystals begin to grow.
Czaja et al. contend that measured fractionations are experimentally induced kinetic effects and note that associated fractionations may be rate dependent.The experimental methodology used has been applied previously to investigations of the kinetics and mechanism of FeS 2 formation and has been shown to be robust.The example …
This paper demonstrated the vital role of Fe(II) in the pyrite for the formation of ROS. Results showed that exogenous addition of Fe(II) significantly enhanced the removal rate of As(III) by pyrite. 2,2 ... Non-linear hydroxyl radical formation rate in dispersions containing mixtures of pyrite and chalcopyrite particles. Geochimica et ...
Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater …
The pyrite formation rate in hydrothermal systems will be intermediate between these extreme values. Isotopic equilibration of FeS with H 2 S is fast [44] and in natural sedimentary and hydrothermal environments pyrite formation is sufficiently slow to permit local isotopic equilibration of FeS and H 2 S reservoirs. In our experiments, initial ...
Experimental and field studies have suggested that large framboidal pyrite grains typically form in sulfide-rich environments and associated with rapid rates of pyrite formation, whereas euhedral pyrite …
Abstract. Pyrite formation has been investigated at 70°C and pH 6-8 by aging precipitated, disordered mackinawite, Fe 9 S 8, and greigite, Fe 3 S 4, in solutions containing aqueous H 2 S, HS-, S x 2-, S 2 O 3 2-, SO 3 2-, colloidal elemental sulfur, and the organic sulfur species thiol, disulfide, and sulfonate.Pyrite formed in all experiments where unoxidized …
For example, pyrite formation proceeds in some cases via the activity of microbial consortia (Thiel et al., 2019), and the rate of its formation and/or the formation of its precursor compounds may be enhanced by the availability of microbial biomass as a template or nucleation site for crystallization (Donald & Southam, 1999; Ferris et al ...
