Готові списки джерел за темами / Arsenian pyrite

Добірка наукової літератури з теми "Arsenian pyrite"

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 28 січня 2023

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Статті в журналах з теми "Arsenian pyrite"

Gopon, Phillip, James O. Douglas, Maria A. Auger, Lars Hansen, Jon Wade, Jean S. Cline, Laurence J. Robb, and Michael P. Moody. "A Nanoscale Investigation of Carlin-Type Gold Deposits: An Atom-Scale Elemental and Isotopic Perspective." Economic Geology 114, no. 6 (September 1, 2019): 1123–33. http://dx.doi.org/10.5382/econgeo.4676.

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Abstract Carlin-type gold deposits are one of the most important gold mineralization styles in the world. Despite their economic importance and the large volume of work that has been published, there remain crucial questions regarding their metallogenesis. Much of this uncertainty is due to the cryptic nature of the gold occurrence, with gold occurring as dispersed nanoscale inclusions within host pyrite rims that formed on earlier formed barren pyrite cores. The small size of the gold inclusions has made determining their nature within the host sulfides and the mechanisms by which they precipitated from the ore fluids particularly problematic. This study combines high-resolution electron probe microanalysis (EPMA) with atom probe tomography (APT) to constrain whether the gold occurs as nanospheres or is dispersed within the Carlin pyrites. APT offers the unique capability of obtaining major, minor, trace, and isotopic chemical information at near-atomic spatial resolution. We use this capability to investigate the atomic-scale distribution of trace elements within Carlin-type pyrite rims, as well as the relative differences of sulfur isotopes within the rim and core of gold-hosting pyrite. We show that gold within a sample from the Turquoise Ridge deposit (Nevada) occurs within arsenian pyrite overgrowth (rims) that formed on a pyrite core. Furthermore, this As-rich rim does not contain nanonuggets of gold and instead contains dispersed lattice-bound Au within the pyrite crystal structure. The spatial correlation of gold and arsenic within our samples is consistent with increased local arsenic concentrations that enhanced the ability of arsenian pyrite to host dispersed gold (Kusebauch et al., 2019). We hypothesize that point defects in the lattice induced by the addition of arsenic to the pyrite structure facilitate the dissemination of gold. The lack of gold nanospheres in our study is consistent with previous work showing that dispersed gold in arsenian pyrite can occur in concentrations up to ~1:200 (gold/arsenic). We also report a method for determining the sulfur isotope ratios from atom probe data sets of pyrite (±As) that illustrates a relative change between the pyrite core and its Au and arsenian pyrite rim. This spatial variation confirms that the observed pyrite core-rim structure is due to two-stage growth involving a sedimentary or magmatic-hydrothermal core and hydrothermal rim, as opposed to precipitation from an evolving hydrothermal fluid.

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Filimonova, Olga, Alexander Trigub, Maximilian Nickolsky, Elena Kovalchuk, Vera Abramova, Mauro Rovezzi, Elena Belogub, Ilya Vikentyev, and Boris Tagirov. "X-ray absorption spectroscopy study of the chemistry of «invisible» Au in arsenian pyrites." E3S Web of Conferences 98 (2019): 05007. http://dx.doi.org/10.1051/e3sconf/20199805007.

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Arsenian pyrite is an abundant mineral occurring in many geological settings at the Earth’s surface, including hydrothermal ore deposits which are the main source of Au. So-called “invisible” (or refractory) form of Au is present in pyrites in all types of these deposits, and its concentration is often directly correlated with As content. Here we report results of the investigation of the local atomic structure of Au in natural (Cu-Au-porphyry) and synthetic (450°C/ 1 kbar, 300°C/ Psat) As-free and As-bearing pyrites by means of X-ray absorption spectroscopy (XAS). In addition, the state of As was determined in pyrite samples from Carlin-type deposit. XANES/EXAFS measurements, compiled with previously published data, revealed the chemical state (valence state, local atomic environment) of Au and As in arsenian pyrites. Au is present in the solid solution state (Au1+ in the Fe position, octahedrally coordinated by S atoms), as well as in Au1+2S clusters (Au1+ linearly coordinated by 2 S atoms). The admixture of As has no effect on the Au valence state and Au-S interatomic distance, except one synthetic sample containing a minor amount of FeAsS. Arsenic mostly incorporates into the anion site in pyrite lattice (S1-↔As1-). Our data demonstrate that pyrites of hydrothermal origin can host up to ~300 ppm of structurally bound “invisible” Au independently of As content.

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Fischer, Alicia, James Saunders, Sara Speetjens, Justin Marks, Jim Redwine, Stephanie R. Rogers, Ann S. Ojeda, Md Mahfujur Rahman, Zeki M. Billor, and Ming-Kuo Lee. "Long-Term Arsenic Sequestration in Biogenic Pyrite from Contaminated Groundwater: Insights from Field and Laboratory Studies." Minerals 11, no. 5 (May 19, 2021): 537. http://dx.doi.org/10.3390/min11050537.

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Pumping groundwater from arsenic (As)-contaminated aquifers exposes millions of people, especially those in developing countries, to high doses of the toxic contaminant. Previous studies have investigated cost-effective techniques to remove groundwater arsenic by stimulating sulfate-reducing bacteria (SRB) to form biogenic arsenian pyrite. This study intends to improve upon these past methods to demonstrate the effectiveness of SRB arsenic remediation at an industrial site in Florida. This study developed a ferrous sulfate and molasses mixture to sequester groundwater arsenic in arsenian pyrite over nine months. The optimal dosage of the remediating mixture consisted of 5 kg of ferrous sulfate, ~27 kg (60 lbs) of molasses, and ~1 kg (2 lbs) of fertilizer per 3785.4 L (1000 gallons) of water. The remediating mixture was injected into 11 wells hydrologically upgradient of the arsenic plume in an attempt to obtain full-scale remediation. Groundwater samples and precipitated biominerals were collected from June 2018 to March 2019. X-ray diffraction (XRD), X-ray fluorescence (XRF), electron microprobe (EMP), and scanning electron microscope (SEM) analyses determined that As has been sequestered mainly in the form of arsenian pyrite, which rapidly precipitated as euhedral crystals and spherical aggregates (framboids) 1–30 μm in diameter within two weeks of the injection. The analyses confirmed that the remediating mixture and injection scheme reduced As concentrations to near or below the site’s clean-up standard of 0.05 mg/L over the nine months. Moreover, the arsenian pyrite contained 0.03–0.89 weight percentage (wt%) of sequestered arsenic, with >80% of groundwater arsenic removed by SRB biomineralization. Considering these promising findings, the study is close to optimizing an affordable procedure for sequestrating dissolved As in industry settings.

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Stefanova, Elitsa, Milen Kadiyski, Stoyan Georgiev, Atanas Hikov, Sylvina Georgieva, and Irena Peytcheva. "Optical cathodoluminescence petrography, combined with SEM and LA-ICP-MS analyses: a case study from the Elatsite porphyry Cu-Au deposit." Review of the Bulgarian Geological Society 83, no. 3 (December 2022): 117–20. http://dx.doi.org/10.52215/rev.bgs.2022.83.3.117.

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In the present research, we have applied a combination of Cold-CL petrography with two in-situ techniques (SEM-EDS and LA-ICP-MS) to study quartz-pyrite-sericite veins with some carbonates from the Elatsite porphyry Cu-Au deposit. Based on Cold-CL images, we found out that these veins are formed during two stages: quartz-pyrite with sericite and later quartz-carbonate with chlorite. Together with the quartz and carbonates small amount of arsenian pyrite, hematite, chalcopyrite, sphalerite, galena and apatite are precipitated. SEM-EDS and LA-ICP-MS allowed determining that the observed zoning of the pyrite from Q-Py stage is due to a variable Co and Ni content. Similarly, the zonal growth of calcite is due to variable Mn content. Pyrite and arsenian pyrite have different trace element composition. Arsenian pyrite has elevated Au, Ag, Cu, Pb, Sb and Tl contents compared to the pyrite. The combination of the three techniques was essential for resolving temporal relationships between the minerals within quartz-pyrite-carbonate veins and changes of the composition of the pyrite from the quartz-pyrite-sericite to the later quartz-carbonate stage.

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Reich, Martin, Stephen E. Kesler, Satoshi Utsunomiya, Christopher S. Palenik, Stephen L. Chryssoulis, and Rodney C. Ewing. "Solubility of gold in arsenian pyrite." Geochimica et Cosmochimica Acta 69, no. 11 (June 2005): 2781–96. http://dx.doi.org/10.1016/j.gca.2005.01.011.

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Stepanov, Aleksandr S., Ross R. Large, Ekaterina S. Kiseeva, Leonid V. Danyushevsky, Karsten Goemann, Sebastien Meffre, Irina Zhukova, and Ivan A. Belousov. "Phase relations of arsenian pyrite and arsenopyrite." Ore Geology Reviews 136 (September 2021): 104285. http://dx.doi.org/10.1016/j.oregeorev.2021.104285.

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Voudouris, Panagiotis, Marianna Kati, Andreas Magganas, Manuel Keith, Eugenia Valsami-Jones, Karsten Haase, Reiner Klemd, and Mark Nestmeyer. "Arsenian Pyrite and Cinnabar from Active Submarine Nearshore Vents, Paleochori Bay, Milos Island, Greece." Minerals 11, no. 1 (December 25, 2020): 14. http://dx.doi.org/10.3390/min11010014.

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Active, shallow-water (2–10 m below sea level) and low temperature (up to 115 °C) hydrothermal venting at Paleochori Bay, nearshore Milos Island, Greece, discharges CO2 and H2S rich vapors (e.g., low-Cl fluid) and high-salinity liquids, which leads to a diverse assemblage of sulfide and alteration phases in an area of approximately 1 km2. Volcaniclastic detritus recovered from the seafloor is cemented by hydrothermal pyrite and marcasite, while semi-massive to massive pyrite-marcasite constitute mounds and chimney-like edifices. Paragenetic relationships indicate deposition of two distinct mineralogical assemblages related to the venting of high-Cl and low-Cl fluids, respectively: (1) colloform As- and Hg-bearing pyrite (Py I), associated with marcasite, calcite, and apatite, as well as (2) porous and/or massive As-rich pyrite (Py II), associated with barite, alunite/jarosite, and late-stage hydrous ferric oxides. Mercury, in the form of cinnabar, occurs within the As-rich pyrite (Py I) layers, usually forming distinct cinnabar-enriched micro-layers. Arsenic in colloform pyrite I shows a negative correlation with S indicating that As1− dominates in the pyrite structure suggesting formation from a relatively reducing As-rich fluid at conditions similar to low-sulfidation epithermal systems. On the contrary, As3+ dominates in the structure of porous to massive pyrite II suggesting deposition from a sulfate-dominated fluid with lower pH and higher fO2. Bulk sulfide data of pyrite-bearing hydrothermal precipitates also show elevated As (up to 2587 ppm) together with various epithermal-type elements, such as Sb (up to 274 ppm), Tl (up to 513 ppm), and Hg (up to 34 ppm) suggesting an epithermal nature for the hydrothermal activity at Paleochori Bay. Textural relationships indicate a contemporaneous deposition of As and Hg, which is suggested to be the result of venting from both high-salinity, liquid-dominated, as well as CO2- and H2S-rich vapor-dominated fluids that formed during fluid boiling. The CO2- and H2S-rich vapor that physically separated during fluid boiling from the high-salinity liquid led to calcite formation upon condensation in seawater together with the precipitation of As- and Hg-bearing pyrite I. This also led to the formation of sulfuric acid, thereby causing leaching and dissolution of primary iron-rich minerals in the volcaniclastic sediments, finally resulting in pyrite II precipitation in association with alunite/jarosite. The Paleochori vents contain the first documented occurrence of cinnabar on the seafloor in the Mediterranean area and provide an important link between offshore hydrothermal activity and the onshore mercury and arsenic mineralizing system on Milos Island. The results of this study therefore demonstrate that metal and metalloid precipitation in shallow-water continental arc environments is controlled by epithermal processes known from their subaerial analogues.

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Cabri, Louis J., Stephen L. Chryssoulis, John L. Campbell, and William J. Teesdale. "Comparison of in-situ gold analyses in arsenian pyrite." Applied Geochemistry 6, no. 2 (January 1991): 225–30. http://dx.doi.org/10.1016/0883-2927(91)90032-k.

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Qiu, Guohong, Tianyu Gao, Jun Hong, Yao Luo, Lihu Liu, Wenfeng Tan, and Fan Liu. "Mechanisms of interaction between arsenian pyrite and aqueous arsenite under anoxic and oxic conditions." Geochimica et Cosmochimica Acta 228 (May 2018): 205–19. http://dx.doi.org/10.1016/j.gca.2018.02.051.

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Deditius, A. P., S. Utsunomiya, R. C. Ewing, and S. E. Kesler. "Nanoscale "liquid" inclusions of As-Fe-S in arsenian pyrite." American Mineralogist 94, no. 2-3 (February 1, 2009): 391–94. http://dx.doi.org/10.2138/am.2009.3116.

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Дисертації з теми "Arsenian pyrite"

Daniel, Blakemore. "Insights into the History of Pyrite Mineralization at the Round Mountain Gold Mine, Nevada: A Detailed Microanalytical Study of the Type 2 Ore." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami15962291791253.

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Song, Jin Kun. "Arsenic removal and stabilization by synthesized pyrite." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3141.

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Kim, Eun Jung. "Macroscopic and spectroscopic investigation of interactions of arsenic with synthesized pyrite." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3138.

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Yao, Xizhi. "Experimental studies on the formation of pyrite and marcasite and the mechanisms of arsenic incorporation." Thesis, Yao, Xizhi (2021) Experimental studies on the formation of pyrite and marcasite and the mechanisms of arsenic incorporation. PhD thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/61494/.

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Iron disulfide (FeS2) has two polymorphs, pyrite and marcasite. Pyrite is the most abundant sulfide in the Earth's crust. Both minerals can host economic amount of gold and environmentally hazardous arsenic and are found to coexist in hydrothermal mineralization. With time, thermodynamically metastable marcasite can transform to pyrite. However, the kinetics of the marcasite to pyrite transformation, and the mechanisms of arsenic incorporation during growth of pyrite are not well-constrained. This thesis presents experimental results and discussions on: (i) the formation of pyrite and marcasite under dry and hydrothermal conditions (Chapter 2 and 3), and (ii) incorporation of arsenic into pyrite during the growth of pyrite on pyrite seeds (Chapter 4). In Chapter 2, the transformation from marcasite to pyrite was studied by in situ synchrotron powder X-ray diffraction (PXRD) at 520 °C and 540 °C, and ex situ anneal/quench experiments at 400 °C, 462 °C, and 520 °C. It was found that the mechanism and kinetics of this transformation depend not only on temperature, but also on particle size, the presence of water vapor, and the presence of pyrite inclusions in marcasite. Under dry conditions, the transformation is limited by surface nucleation and occurs via epitaxial nucleation of pyrite on marcasite, with {100}pyrite//{101}marcasite and {001}pyrite//{010}marcasite. In contrast, in the presence of water vapor, there is little crystallographic orientation relationship between the two phases; the transformation is limited by surface nucleation, but modification of the surface properties by water vapor results in a different nucleation mechanism, and consequently different kinetics. Kinetic analysis estimates a half-life of 1.5 Ma at 300 °C for the transformation under dry conditions with pyrite-free marcasite grains (<38 μm), but this estimation should be used with extreme caution due to the complexity of the process. From synchrotron X-ray fluorescence elemental mapping, trace elements (As and Pb) play an insignificant role in the transformation. However, the presence of a fluid phase changes the behavior of Pb. Under dry conditions randomly oriented particles of galena formed in pyrite, while under water vapor conditions arrays of nano-to-microparticles of galena precipitated in pores. This chapter highlights that although the natural occurrence of marcasite can indicate low temperature environments, precise estimation of temperature should not be made without considering the influences from various reaction parameters. In Chapter 3, combined in-situ synchrotron PXRD and ex situ experiments were conducted under hydrothermal conditions at 190 °C and 210 °C and pH 1, aiming to study the controls on the precipitation of pyrite and marcasite from supersaturated hydrothermal solutions and the kinetics of hydrothermal transformation from marcasite to pyrite. In situ PXRD experiments show the important role of saturation index on the precipitation of pyrite and marcasite; at 190 °C, hydrothermal fluids rich in ΣS(-II) (0.9 mM) favors the precipitation of nanocrystalline pyrite (23 nm) due to high saturation index, while S(-II)-free fluids produce a mixture of marcasite and pyrite nanocrystals (21-46 nm) due to low saturation index. Fluid/rock ratio (70 and 120 g/g at 210 °C) can affect saturation index of the fluids, resulting in complex nucleation and crystal growth dynamics such as the evolution of crystallite size, phase abundance, and pyrite/marcasite ratio. Ex situ experiments show the rapid transformation from marcasite to pyrite at 210 °C; around 83% marcasite is transformed to pyrite in just 3 weeks, compared to 4.3 million years or 6.3 trillion years at 210 °C based on extrapolation using the kinetic models reported in early studies under dry conditions. These results suggest that saturation index influences the dynamics of precipitation under hydrothermal conditions and controls the phase selection between pyrite and marcasite, and that marcasite may not survive over geological time in low temperature environments in the presence of acidic hydrothermal fluids. In Chapter 4, the formation of zoned arsenian pyrite was studied by growing pyrite on pyrite seeds in O2-free, As-enriched fluids at 200 °C and pH 7. The distribution and concentrations of As in pyrite, as well as the morphology of the zoning are influenced by sulfur source; i.e., native sulfur or Na2S2O3·5H2O. For experiments with native sulfur, up to four concentric alternate zones of As-rich (first zone on pyrite seed) and As-free pyrite grow on pyrite seeds. For experiments with Na2S2O3·5H2O, an aggregate of concentrically zoned pyrite microparticles (~1 µm) precipitate on the surface of pyrite seeds. Based on EMPA, the maximum concentration of As is 4.3 wt. %. However, the TEM-EDS analyses reveal ≤5.8 wt. % of As. HRTEM and selected area electron diffraction (SAED) pattern combined with EBSD analyses document epitaxial growth of As-pyrite on pyrite seed in the presence of native sulfur, but aggregation of randomly oriented aggregates of pyrite microparticles in the presence of thiosulfate. High-angle annular dark-field scanning TEM (HAADF-STEM), HRTEM observations, and EDS mapping show a sharp boundary and trails of pores between the pyrite seed and the product and between the growth zones. In the presence of native sulfur, the thickness of the As-pyrite growth zones is ~ 50 nm, while the subsequently formed growth zones of “barren” pyrite are ~5000 nm thick. X-ray absorption near edge structure (XANES) analyses reveal that speciation of As in pyrite depends on the S-source: (i) anionic As(-I) substitutes for S in pyrite as As2 pair when native S is used, and (ii) cationic As(II)/As(III) substitutes for Fe when thiosulfate is used. Our experiments show that the incorporation of As into pyrite and the formation and morphology of pyrite growth zones are controlled by the source of sulfur in hydrothermal fluids. This thesis highlights the factors that control the mechanisms of the formation and transformation of pyrite and marcasite and the dependence of As incorporation into arsenian pyrite structure as a function of S and As source in the presence of pyrite seeds. These outcomes should benefit our understanding of the formation and alteration of Carlin-type, epithermal, volcanic-hosted massive sulfide (VMS), and orogenic Au deposits.

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West, Nicole Renee. "Arsenic Release from Chlorine Promoted Oxidation of Pyrite in the St. Peter Sandstone Aquifer, Eastern Wisconsin." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32451.

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High arsenic concentrations (>100 ppb) have been measured in wells completed in the Ordovician St. Peter sandstone aquifer of eastern Wisconsin. The primary source of arsenic is As-bearing sulfide minerals within the aquifer. There is concern that periodic disinfection of wells by chlorination may facilitate arsenic release to groundwater by increasing the rate of sulfide mineral oxidation. Current guidance from the Wisconsin Department of Natural Resources recommends a â low-doseâ treatment of 20% of the chlorine strength and 10% of the of the contact time of chlorine treatments used in non-arsenic impacted wells for well disinfection and biofilm removal. In order to provide information pertaining to WDNRâ s recommendations, St. Peter sulfide minerals were reacted with a range of chlorine â shock-treatmentsâ similar to those occurring in wells. This study focuses on abiotic processes that mobilize arsenic from the solid phase during controlled exposure to chlorinated solutions.

Thin sections were made from aquifer material collected at Leonardâ s Michael quarry, located in Winnebago County, Wisconsin. Bulk arsenic content of this material was measured as 674 ppm. Quantitative EPMA analysis shows As zoning in pyrite grains with concentrations up to 1 wt. % As. After mineral characterization, the thin sections were exposed to solutions of 60 mg/L â free chlorine,â 1200 mg/L â free chlorine,â and nanopure water (control) at pH 7.0 and pH 8.5 for 24 hours. Thin sections were then analyzed to measure changes in the pyrite surfaces. For solution experiments, aquifer material was crushed to between 250 Î¼m and 355 Î¼m mesh sizes (S.A. ~ 50 cm2/g â 60 cm2/g, Foust et al. 1980) and reacted under the same conditions as the thin sections in a batch reactor. Solution samples were collected periodically during the 24 hour exposure and analyzed for arsenic, iron, and sulfate ion.

Pyrite oxidation is shown to dramatically increase with increasing chlorine concentrations as shown by measurements of released sulfate ion, used here as the reaction progress variable. EPMA maps also reveal complete oxidation of pyrite cements to Fe-oxyhydroxides at 1200 mg/L â free chlorineâ and pH 7.0. This behavior does not occur at lower concentrations or higher pH. Arsenic release to solution does not appear to be directly correlated to increasing chlorine concentrations, but is governed by Fe-oxyhydroxide nucleation, which inhibits the release of dissolved arsenic at higher concentrations of chlorine.
Master of Science

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Lazareva, Olesya. "Detailed geochemical and mineralogical analyses of naturally occurring arsenic in the Hawthorn Group." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000521.

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Bennett, Andrew John. "Relationship between gold and arsenic in hydrothermal pyrite : experimental results and applications to submicroscopic gold in massive sulphide deposits." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421978.

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Jones, Gregg William. "Investigation of the Mechanisms for Mobilization of Arsenic in Two ASR Systems in Southwest Central Florida." Thesis, University of South Florida, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3741476.

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Aquifer storage and recovery (ASR) is a strategy in which water is injected into an aquifer when it is plentiful and pumped from the aquifer when water is scarce. An impediment to ASR in Florida is leaching of naturally-occurring arsenic from limestone of the Upper Floridan Aquifer System (UFAS) into stored water. The concentration of arsenic in surface water, which serves as the recharge water for many ASR systems, and native groundwater is usually much less than 3.0 µ/L. However, data from ASR wells in Florida show that arsenic in recovered water frequently exceeded the 10 µg/L maximum contaminant level (MCL) established by the Environmental Protection Agency and were as high as 130.0 µg/L. The cause of elevated arsenic concentrations is displacement of reduced native groundwater with oxygenated surface water that dissolves arsenic-bearing pyrite in limestone. Although arsenic can be removed from recovered water during final treatment, mobilization of arsenic in the aquifer at levels that exceed the MCL is problematic under federal regulations.

This dissertation investigated a number of aspects of the ASR/arsenic problem to provide additional insights into the mechanisms of arsenic mobilization and measures that could be taken to avoid or reduce the release of arsenic during ASR operations.

Chapter 2, involved development of a geochemical model to simulate an ASR system’s injection of oxygenated surface water into reduced groundwater to determine whether aquifer redox conditions could be altered to the degree of pyrite instability. Increasing amounts of injection water were added to the storage-zone in a series of steps and resulting reaction paths were plotted on pyrite stability diagrams. Unmixed storage-zone water in wells plotted within the pyrite stability field indicating that redox conditions were sufficiently reducing to allow for pyrite stability. Thus arsenic is immobilized in pyrite and its concentration in groundwater should be low. During simulation, as the injection/storage-zone water ratio increased, redox conditions became less reducing and pyrite became unstable. The result would be release of arsenic from limestone into storage-zone water.

Chapter 3 examined the importance of maintaining a substantial volume of stored water around an ASR well to prevent recovery of reduced native groundwater to the vicinity of the well. Depleting the stored water and recovering reduced native groundwater would result in dissolution of arsenic-bearing hydrous ferric oxide (HFO) and release of arsenic into water recovered from the ASR well. Injection/recovery volumes for each cycle for each well were tracked to determine if a substantial volume of stored water was maintained for each cycle or if it was depleted so that reduced native groundwater was brought back to the well. Each well was assigned to either the “storage zone maintained group” where a zone of stored water was established in early cycles and largely maintained through the period of investigation, or the “storage-zone depleted group” where a zone of stored water was either established in later cycles and/or was depleted during the period of investigation. Graphical and statistical analyses verified that maximum arsenic concentrations for storage-zone maintained wells were nearly always lower in each cycle and declined below the MCL after fewer cycles than those of storage-zone depleted wells.

Chapter 4 was a mineralogical investigation of cores located at 20 m (ASR core 1), 152 m (ASR core 2), and 452 m (ASR core 3) from operating ASR wells to determine where mobilized arsenic in limestone is precipitated during ASR. If arsenic is precipitated distally, reduced concentrations of elements in pyrite, (iron, sulfur, arsenic, etc.) would be expected in ASR core 1 relative to more distant cores and there would be noticeable changes in appearance of pyrite crystals due to enhanced oxidation. The results showed that mean concentrations of the elements were lowest in ASR core 2, which did not support distal precipitation. However, scanning electron microscopy identified well-defined pyrite framboids only in core 3 while framboids in ASR cores 1 and 2 were less clear and distinct, indicating pyrite oxidation in cores closest to ASR wells.

Statistical comparison of concentrations of iron, sulfur, and arsenic between the three ASR cores and 19 control cores not subject to ASR, showed that mean concentrations in ASR cores 1 and 2 were statistically similar to concentrations in control cores. This indicated that concentrations in ASR cores 1 and 2 had not been significantly reduced by ASR. The concentrations of elements were higher in ASR core 3 than in ASR cores 1 and 2 and control cores and statistically dissimilar to all but one control core. This indicated natural heterogeneity in core 3 rather than diminution of elements in ASR cores 1 and 2 due to ASR. The statistical analysis supported local precipitation. Once arsenic is mobilized from dissolved pyrite, it is rapidly complexed with precipitated HFO near the well. As long as all of the stored water is not removed during recovery so that reduced native groundwater is brought back to the well, HFO remains stable and complexed with arsenic. The concentration of elements would not have been lowest in ASR core 1 for this reason and because calculations showed that the mass of arsenic removed during recovery events prior to coring was minor compared to the total in limestone surrounding the well. The implications of this are that while large quantities of arsenic are present near the ASR well, only a small percentage may be available for dissolution. Most arsenic occurs with pyrite in limestone, which may insulate it from exposure to oxidized injection water. Water recovered from ASR wells may continue to have low concentrations of arsenic indefinitely because as limestone is dissolved, more pyrite becomes exposed and available for dissolution.

The primary contribution of this dissertation to understanding and overcoming the arsenic problem in ASR systems is the empirical data developed to support or challenge important ASR/arsenic hypotheses. These data were used to 1) establish that background concentrations of arsenic in groundwater of the Suwannee Limestone were less than 1µg/L, 2) demonstrate that redox conditions necessary for pyrite in limestone to become unstable and dissolve occur when oxygenated surface water is injected into the aquifer, 3) demonstrate that the concentration of pyrite in the Suwannee Limestone is spatially variable to a high degree, 4) support the hypothesis that following injection of oxygenated surface water, pyrite in limestone dissolves and releases arsenic into solution and HFO forms and complexes with the arsenic near the ASR well, 5) propose that only a small percentage of pyrite near an ASR well may be available for dissolution during each cycle because most occurs in the limestone matrix and is isolated from injection water, 6) propose that as a result of the previous conclusion, water recovered from ASR systems may continue to have low concentrations of arsenic indefinitely because as limestone that contains pyrite is dissolved with each cycle, additional pyrite is exposed and is available for dissolution, and 7) support the effectiveness of maintaining a zone of stored water in an ASR well as an effective means of minimizing arsenic in recovered water during ASR.

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Phan, Thi Hai Van. "L'arsenic dans les écosystèmes du sud-est asiatique : Mekong Delta Vietnam." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU003/document.

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On retrouve des contaminations d’aquifèr à l’arsenic dans touts les deltaï de l'Asie du Sud-Est, y compris dans le delta du Mékong, ce qui affecte la santé de millions de personnes. L’arsenic est très sensible aux fluctuations des conditions redox qui sont générés par les cycles alternés humides/secs pendant la saison de mousson. Une étude sur les caractéristiques géophysiques et chimiques du sol et des eaux souterraines dans le district de An Phu, dans le haut du delta du Mékong au Vietnam, suggère une forté contamination à l’As dans cette région. Les données chimiques et géophysiques indiquent une forte corrélation entre concentrations dans les eaux souterraines anoxiques et conductivité des sols. La liberation de l’arsenic est associée à la dissolution réductrice induih par des microorganisms des colloïdes et (oxyhydr)oxydes de fer dans des conditions d'oxydo-réduction oscillantes. La présence de bactéries sulforéductrices a le potentiel de stabiliser l’arsenic dans la phase solide et de l’atténuer dans la phase aqueuse par adsorption / désorption de l’arsenic sur les (oxyhydr)oxydes, et / ou sulfures de fer via la formation de complexes thiols. En raison de la teneur en pyrite élevée dans les sédiments, l'oxydation de la pyrite peut abaisser le pH et conduire à l'inhibition de la réduction microbienne du sulfate et aime empêcher la séquestration de l’arsenic dissous. Bien que le cycle biogéochimique de l’arsenic dans un système dynamique d’oxydoréduction soit une problématique complexe, il a été possible de renforcer notre compréhension de ce système
Aquifer arsenic (As) contamination is occuring throughout deltaic areas of Southeast Asia, including the Mekong Delta, and affects the health of millions of people. As is highly sensitive to fluctuations of redox conditions which are generated by the alternating wet-dry cycles during the monsoonal seasons. A survey of geophysical and chemical characteristics of soil and groundwater in the An Phu district, located in the vicinity of the Mekong Delta in Vietnam, shows the occurrence high As aqueous concentration in this region. Chemical and geophysical data indicate a strong positive correlation between As concentrations in the anoxic groundwater and conductivity of soils. In addition, mechanisms of As release are shown to be associated with colloidal and iron (oxyhydr)oxides which undergo microbial mediated reductive dissolution under redox oscilatting conditions. The presence of sulfate microbial reduction potentially stabilizes As in the solid phase and diminish As in the aqueous phase through the adsorption/desorption of As onto iron (oxyhydr)oxides and/ or sulfides with formation of thiols complexes in solid phase. Because of the high pyrite content in sediment, pyrite oxidation may drop in pH values, leads to inhibition of sulfate reducing bacteria and reduces sequestration of dissolved As. Although the biogeochemical cycling of redox sensitive species such as As in dynamic systems is challenging, it has been possible to strengthen our collective understanding of such system

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Dippold, Angela C. "Detailed Geochemical Investigation of the Mineralogic Associations of Arsenic and Antimony Within the Avon Park Formation, Central Florida: Implications for Aquifer Storage and Recovery." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002992.

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Частини книг з теми "Arsenian pyrite"

Wolthers, M., I. B. Butler, D. Rickard, and P. R. D. Mason. "Arsenic Uptake by Pyrite at Ambient Environmental Conditions: A Continuous-Flow Experiment." In ACS Symposium Series, 60–76. Washington, DC: American Chemical Society, 2005. http://dx.doi.org/10.1021/bk-2005-0915.ch005.

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Carbonell-Barrachina, Ángel A., Asunción Rocamora, Carmen García-Gomis, Francisco Martínez-Sánchez,, and Francisco Burló. "Arsenic and Zinc Biogeochemistry in Acidified Pyrite Mine Waste from the Aznalcóllar Environmental Disaster." In ACS Symposium Series, 181–99. Washington, DC: American Chemical Society, 2002. http://dx.doi.org/10.1021/bk-2003-0835.ch014.

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Dave, Shailesh R., and K. H. Gupta. "Interactions of Acidithiobacillus ferrooxidans with Heavy Metals, Various Forms of Arsenic and Pyrite." In Advanced Materials Research, 423–26. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-452-9.423.

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Dobak, Paul J., François Robert, Shaun L. L. Barker, Jeremy R. Vaughan, and Douglas Eck. "Chapter 15: Goldstrike Gold System, North Carlin Trend, Nevada, USA." In Geology of the World’s Major Gold Deposits and Provinces, 313–34. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.15.

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Abstract The Eocene Goldstrike system on the Carlin Trend in Nevada is the largest known Carlin-type gold system, with an endowment of 58 million ounces (Moz) distributed among several coalesced deposits in a structural window of gently dipping carbonate rocks below the regional Roberts Mountains thrust. The 3.5- × 2.5-km Goldstrike system is bounded to the east by the Post normal fault system and to the south by the Jurassic Goldstrike diorite stock and is partly hosted in the favorable slope-facies apron of the Bootstrap reef margin that passes through the system. The carbonate and clastic sedimentary sequence is openly folded, cut by sets of reverse and normal faults, and intruded by the Jurassic Goldstrike stock and swarms of Jurassic and Eocene dikes, establishing the structural architecture that controlled fluid flow and distribution of Eocene mineralization. A proximal zone of permeability-enhancing decarbonatization with anomalous gold (>0.1 ppm) extends a few hundreds of meters beyond the ore footprint and lies within a carbonate δ18O depletion anomaly extending ~1.4 km farther outboard. The full extent of the larger hydrothermal system hosting Goldstrike and adjacent deposits on the northern Carlin Trend is outlined by a 20- × 40-km thermal anomaly defined by apatite fission-track analyses. The bulk of the mineralization is hosted in decarbonatized sedimentary units with elevated iron contents and abundant diagenetic pyrite relative to background. Gold is associated with elevated concentrations of As, Tl, Hg, and Sb, and occurs in micron-sized arsenian pyrite grains or in arsenian pyrite overgrowths on older, principally diagenetic pyrite, with sulfidation of available iron as the main gold precipitation mechanism. The intersection of a swarm of Jurassic lamprophyre dikes with the edge of the limestone reef provided a favorable deeply penetrating structural conduit within which a Jurassic stock acted as a structural buttress, whereas the reef’s slope-facies apron of carbonate units, with high available iron content, provided a fertile setting for Carlin-type mineralization. The onset of Eocene extension coupled with a southwestward-sweeping Cenozoic magmatic front acted as the trigger for main-stage gold mineralization at 40 to 39 Ma. All these factors contributed to the exceptional size and grade of Goldstrike.

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Vaughan, Jeremy, Carl E. Nelson, Guillermo Garrido, Jose Polanco, Valery Garcia, and Arturo Macassi. "Chapter 20: The Pueblo Viejo Au-Ag-Cu-(Zn) Deposit, Dominican Republic." In Geology of the World’s Major Gold Deposits and Provinces, 415–30. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.20.

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Abstract The world-class Pueblo Viejo Au deposit in the central Dominican Republic is one of the largest high-sulfidation epithermal Au deposits globally, with past production plus resources and reserves of 41.7 million ounces (Moz) in the Moore and Monte Negro deposits. Mineralization occurs within a 2- × 2-km Early Cretaceous volcano-sedimentary basin filled with felsic volcanic and volcaniclastic rocks, interlayered carbonaceous sedimentary units, and underlying andesitic flows and tuffs. The volcanic stratigraphy was developed during a period of tholeiitic magmatism that transitioned to calc-alkaline magmatism at the time of emplacement of the late- to postmineral Monte Negro dike (~109 Ma). Additional geologic controls to mineralization include high-angle, NE- and NW-faulting, phreatomagmatic breccias, and possible volcanic domes. Mineralization is present across the stratigraphic sequence, with mineralization at Moore dominantly hosted within quartz-bearing volcaniclastic rocks and overlying carbonaceous sedimentary units, whereas that at Monte Negro is in the andesitic sequence as well as overlying epiclastic and sedimentary units. Alteration at the shallowest level is dominated by quartz-pyrophyllite, whereas alunite alteration defines the deep roots to the ore-forming environment. Mineralization comprises early disseminated-type and late veins filled with pyrite ± sphalerite. Hypogene ore is refractory in nature, with Au in solid solution or as mineral inclusions within arsenian pyrite. Re-Os ages of 113.4 ± 2.6 Ma for auriferous pyrite along with new geologic observations appear to confirm an Early Cretaceous age for mineralization, although Re-Os enargite ages suggest the possibility of a second mineralization event in the Eocene.

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Simmons, Stuart F., Benjamin M. Tutolo, Shaun L. L. Barker, Richard J. Goldfarb, and François Robert. "Chapter 38: Hydrothermal Gold Deposition in Epithermal, Carlin, and Orogenic Deposits." In Geology of the World’s Major Gold Deposits and Provinces, 823–45. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.38.

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Abstract Epithermal, Carlin, and orogenic Au deposits form in diverse geologic settings and over a wide range of depths, where Au precipitates from hydrothermal fluids in response to various physical and chemical processes. The compositions of Au-bearing sulfidic hydrothermal solutions across all three deposit types, however, are broadly similar. In most cases, they comprise low-salinity waters, which are reduced, have a near-neutral pH, and CO2 concentrations that range from <4 to >10 wt %. Experimental studies show that the main factor controlling the concentration of Au in hydrothermal solutions is the concentration of reduced S, and in the absence of Fe-bearing minerals, Au solubility is insensitive to temperature. In a solution containing ~300 ppm H2S, the maximum concentration of Au is ~1 ppm, representing a reasonable upper limit for many ore-forming solutions. Where Fe-bearing minerals are being converted to pyrite, Au solubility decreases as temperature cools due to the decreasing concentration of reduced S. High Au concentrations (~500 ppb) can also be achieved in strongly oxidizing and strongly acidic chloride solutions, reflecting chemical conditions that only develop during intense hydrolytic leaching in magmatic-hydrothermal high-sulfidation epithermal environments. Gold is also soluble at low to moderate levels (10–100 ppb) over a relatively wide range of pH values and redox states. The chemical mechanisms which induce Au deposition are divided into two broad groups. One involves achieving states of Au supersaturation through perturbations in solution equilibria caused by physical and chemical processes, involving phase separation (boiling), fluid mixing, and pyrite deposition via sulfidation of Fe-bearing minerals. The second involves the sorption of ionic Au on to the surfaces of growing sulfide crystals, mainly arsenian pyrite. Both groups of mechanisms have capability to produce ore, with distinct mineralogical and geochemical characteristics. Gold transport and deposition processes in the Taupo Volcanic Zone, New Zealand, show how ore-grade concentrations of Au can accumulate by two different mechanisms of precipitation, phase separation and sorption, in three separate hydrothermal environments. Phase separation caused by flashing, induced by depressurization and associated with energetic fluid flow in geothermal wells, produces sulfide precipitates containing up to 6 wt.% Au from a hydrothermal solution containing a few ppb Au. Sorption on to As-Sb-S colloids produces precipitates containing tens to hundreds of ppm Au in the Champagne Pool hot spring. Sorption on to As-rich pyrite also leads to anomalous endowments of Au of up to 1 ppm in hydrothermally altered volcanic rocks occurring in the subsurface. In all of these environments, Au-undersaturated solutions produce anomalous concentrations of Au that match and surpass typical ore-grade concentrations, indicating that near-saturated concentrations of dissolved metal are not a prerequisite for generating economic deposits of Au. The causes of Au deposition in epithermal deposits are related to sharp temperature-pressure gradients that induce phase separation (boiling) and mixing. In Carlin deposits, Au deposition is controlled by surface chemistry and sorption processes on to rims of As-rich pyrite. In orogenic deposits, at least two Au-depositing mechanisms appear to produce ore; one involves phase separation and the other involves sulfidation reactions during water-rock interaction that produces pyrite; a third mechanism involving codeposition of Au-As in sulfides might also be important. Differences in the regimes of hydrothermal fluid flow combined with mechanisms of Au precipitation play an important role in shaping the dimensions and geometries of ore zones. There is also a strong link between Au-depositing mechanisms and metallurgical characteristics of ores.

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Rickard, David. "Hell and Black Smokers." In Pyrite. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190203672.003.0009.

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Most of the important metal ores in medieval and ancient times were pyrite-rich sulfides. These pyrite-rich ores were a major source of a suite of valuable commodities such as sulfur, arsenic, copper, lead, zinc, and nickel, as well as some gold and silver. This is why in 1725 Henckel could devote a 1,000-page volume to pyrites, sensu lato. Because of its relative abundance, its potential economic importance, and its exotic composition compared with the rock-forming minerals, pyrite has played a key role through the ages in developing ideas of how minerals and ore deposits form. During the last century, pyrite became an even more important mineral in discussions of ore genesis because it is also a key component of sediments. This led to conflicting theories of ore genesis, in which the ore minerals were formed in the sediments or introduced later, often by processes related to volcanism. The conflict between adherents of these theories continues to this day. Pyrite constituted a key, but sometimes uncomfortable, mineral in ancient theories of mineral formation. It was relatively common and often economically important. However, it contained sulfur as a key constituent and this contrasted it to many other common minerals and rocks in that this meant that pyrite could be changed by heating. Heating released sulfur from pyrite, leaving a residue of stony slag. The ancients also recognized sulfur as a special material since it occurred in solid, liquid, and gaseous form, rather like water. Any theory of mineral formation needed to explain how this protean element got into pyrite. This problem was compounded by the fact, discussed in Chapter 3, that for some unknown reason the ancients did not know that pyrite contained iron. Ancient theories of mineral formation divide into three categories: (a) the Genesis theory: that all minerals were formed by God during the creation of the Earth; (b) the Aristotelian theory: that all minerals were formed at depth in the Earth through the interactions of the four basic elements; and (c) the Alchemical theory: that minerals were formed from combinations of mercury and sulfur.

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"arsenical pyrites." In Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 70. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41714-6_12723.

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Muntean, John L. "Chapter 36: Carlin-Type Gold Deposits in Nevada: Geologic Characteristics, Critical Processes, and Exploration." In Geology of the World’s Major Gold Deposits and Provinces, 775–95. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.36.

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Abstract Carlin-type gold deposits in Nevada account for ~5% of worldwide annual gold production, typically about ~135 metric tons (t) (~4.5 Moz) per year. They are hydrothermal epigenetic replacement bodies hosted predominantly in carbonate-bearing sedimentary rocks. They are known for their “invisible” gold that occurs in the crystal structure of pyrite. Over 95% of the production from these deposits is from four clusters of deposits, which include the Carlin trend and the Cortez, Getchell, and Jerritt Canyon camps. Despite differences in the local geologic settings, the characteristics of the deposits are very similar in the four clusters. Shared characteristics include: (1) alteration characterized by carbonate dissolution, silicate argillization, and silicification; (2) ore formation characterized by auriferous arsensian pyrite, typically as rims on preore pyrite, followed by late open-space deposition of orpiment, realgar, stibnite, and other minerals; (3) Ag/Au ratios of <1 in ore; (4) an As-Hg-Sb-Tl geochemical signature; (5) low temperatures (~160°–240°C) and salinities of ore fluids (~1–6 wt % NaCl equiv) and fairly shallow depths of formation (<~2–3 km); and (6) lack of mineral and elemental zoning around ore. The four clusters share regional geologic controls related to formation as follows: (1) along the rifted margin of a craton, (2) within the slope facies of a passive margin sequence dominated by carbonates, (3) in the lower plate of a regional thrust fault, and (4) during a narrow time interval in the late Eocene (~42–34 Ma). The geometries and ore controls of the deposits in the four clusters are also very similar. At the deposit scale, ore and hydrothermal alteration are commonly associated with high-angle faults and preore low-angle contractional structures, including thrust faults and folds. The high-angle faults acted as fluid pathways for upwelling ore fluids, which were then diverted into lower angle favorable strata and contractional structures, where fluid-rock interaction led to replacement of carbonate and formation of ore. Rheologic contrasts between lithologies were also critical in diverting fluids into wall rocks. Common rheologic contrasts include contacts between thin- and thick-bedded lithologic units and the margins of contact metamorphic aureoles associated with Mesozoic intrusions. The similarities suggest common processes. Four critical processes are apparent: (1) development of source(s) for gold and other critical components of the ore fluids, (2) formation of fluid pathways, (3) water-rock interaction and gold deposition, and (4) a tectonic trigger, which was renewal of magmatism and a change from contraction to extension in the late Eocene. Consensus exists on these processes, except for the source of gold and other components of the ore fluid, with most models calling upon either a magmatic-hydrothermal source or a crustal source, where metals were scavenged by either meteoric or metamorphic fluids. Future research should focus on Carlin-style deposits in Nevada that exhibit epithermal characteristics and deposits that appear to have a clear genetic association with magmatic-hydrothermal systems associated with upper crustal intrusions. Rather than discrete types of ore deposits, there may be continua between Carlin-type gold deposits, epithermal deposits, and distal disseminated deposits, with the four large camps representing an end member.

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Leary, Stephen, Richard H. Sillitoe, Jorge Lema, Fernando Téliz, and Diego Mena. "Chapter 21: Geology of the Fruta del Norte Epithermal Gold-Silver Deposit, Ecuador." In Geology of the World’s Major Gold Deposits and Provinces, 431–50. Society of Economic Geologists, 2020. http://dx.doi.org/10.5382/sp.23.21.

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Abstract Fruta del Norte is a completely concealed and extremely well-preserved, Late Jurassic epithermal gold-silver deposit of both low- and intermediate-sulfidation type, which is located in the remote Subandean mountain ranges of southeastern Ecuador. Currently defined indicated resources are 23.8 million metric tons (Mt) averaging 9.61 g/t Au and the total endowment is 9.48 Moz Au. The deposit, notable for the widespread occurrence of visible gold and bonanza grades, will be bulk mined underground. Fruta del Norte was discovered in 2006 during greenfield exploration and systematic drill testing of a conceptual geologic model, which predicted that auriferous veins would occur in andesitic volcanic rocks inferred to underlie a zone of arsenic- and antimony-anomalous silicification in fluvial conglomerate. The host andesitic volcanic rocks, crosscutting feldspar porphyry, and associated phreatic breccia are part of a roof pendant in the Zamora batholith. Together, they are products of a continental-margin volcanoplutonic arc of Middle to Late Jurassic age. The deposit lies beneath the northern extremity of the ~16-km-long, Suárez pull-apart basin where it is localized by steep, second-order faults within the regionally extensive Las Peñas strike-slip fault zone. The pull-apart basin was progressively filled by fluvial conglomerate, dacitic ignimbrite, finer grained siliciclastic sedimentary rocks, and, finally, andesite flows. The Fruta del Norte deposit comprises a 1.3-km-long and up to >300-m-wide vein stockwork associated with quartz-illite-pyrite alteration. The deposit comprises two principal vein types, one in the south dominated by quartz, manganoan carbonates, and abundant base metal sulfides and the other in the north dominated by manganese- and base metal-poor quartz, chalcedony, and calcite. Adularia is a minor gangue mineral in both. Both vein types are abruptly transitional upward and westward to a third important ore type characterized by intense silicification and chalcedony veining, with disseminated and veinlet marcasite (± pyrite). An extensive silica sinter horizon directly overlies the andesitic rocks and/or occurs as interbeds in the lowermost 20 m of the conglomerate and, consequently, is in unusual proximity to the underlying gold-silver orebody. Much of the conglomerate lacks silicification except for a narrow, steeply inclined zone exposed above the deposit, which led to its discovery.

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Тези доповідей конференцій з теми "Arsenian pyrite"

Frank, Mark R., Matthew Mann, and Robert J. Bodnar. "A POSSIBLE EXPLANATION FOR THE CORRELATION OF GOLD AND ARSENIC WITHIN PYRITE, ARSENIAN PYRITE, AND ARSENOPYRITE." In 52nd Annual North-Central GSA Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018nc-312643.

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Hashimoto, Yohey. "Arsenic Sequestration by Pyrite Framboids." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.971.

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Wilson, Theodore Jeffrey, Eric Levitt, Shahrzad S. Ghandehari, Ming-Kuo Lee, James A. Saunders, Jim Redwine, Justin Marks, et al. "PYRITE BIOMINERALIZATION AND ARSENIC SEQUESTRATION AT A FLORIDA INDUSTRIAL SITE: IMAGING AND GEOCHEMICAL ANALYSIS." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-297861.

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Zhang, He, Yuanfeng Cai, Gang Sha, Joël Brugger, Allan Pring, Pei Ni, Gujie Qian, Zhenjiao Luo, Yang Zhang, and Wei Tan. "Arsenic Influence on the Distribution and Modes of Occurrence of Gold during the Fluid-Pyrite Interaction: A Case Study of Pyrite from the Qiucun Gold Deposit, China." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.3098.

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Fischer, Alicia, Ming-Kuo Lee, James Saunders, Sara Gilley, Justin Marks, and Jim Redwine. "FIELD AND LABORATORY INVESTIGATIONS OF GROUNDWATER ARSENIC SEQUESTRATION IN BIOGENIC PYRITE AT AN INDUSTRIAL SITE IN FLORIDA." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-334367.

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Fischer, Alicia, James Saunders, Sara Speetjens, Justin Marks, Jim Redwine, Stephanie Rogers, Ann Ojeda, and Ming-Kuo Lee. "FIELD AND LABORATORY INVESTIGATIONS OF GROUNDWATER ARSENIC SEQUESTRATION IN BIOGENIC PYRITE AT AN INDUSTRIAL SITE IN FLORIDA." In Southeastern Section-70th Annual Meeting-2021. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021se-362012.

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Rahman, Md Mahfujur. "ARSENIC SEQUESTRATION IN NATURALLY OCCURRING BIOGENIC PYRITE IN THE HOLOCENE FLUVIAL AQUIFERS IN UPHAPEE WATERSHED, MACON COUNTY, ALABAMA." In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-371482.

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Vietas, J., and G. Talaska. "220. Co-Exposure of Arsenite and Benzo(A)Pyrene: Effect of Glutathione on DNA Adduct Levels." In AIHce 2006. AIHA, 2006. http://dx.doi.org/10.3320/1.2758931.

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Meier, B., K. LaDow, B. Schumann, and G. Talaska. "27. Dose-Response of Low Dose Co-Exposures to Arsenic and Benzo[A]Pyrene in Mice." In AIHce 2004. AIHA, 2004. http://dx.doi.org/10.3320/1.2758334.

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Rddad, Larbi. "ROLE OF EUXINIC CONDITIONS IN ADSORBING ARSENIC IN ORGANIC MATTER AND PYRITE PRESERVED IN THE LOCKATONG FORMATION OF NEWARK: IMPLICATION TO THE QUALITY OF GROUNDWATER." In 51st Annual Northeastern GSA Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016ne-272262.

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Звіти організацій з теми "Arsenian pyrite"

Kyllönen, Katriina, Karri Saarnio, Ulla Makkonen, and Heidi Hellén. Verification of the validity of air quality measurements related to the Directive 2004/107/EC in 2019-2020 (DIRME2019). Finnish Meteorological Institute, 2020. http://dx.doi.org/10.35614/isbn.9789523361256.

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This project summarizes the results from 2000–2020and evaluates the trueness andthequality control (QC) procedures of the ongoing polycyclic aromatic hydrocarbon (PAH)and trace element measurements in Finlandrelating to Air Quality (AQ) Directive 2004/107/EC. The evaluation was focused on benzo(a)pyrene and other PAH compounds as well as arsenic, cadmium and nickel in PM10and deposition. Additionally, it included lead and other metals in PM10and deposition, gaseous mercury and mercury deposition, andbriefly other specificAQ measurements such as volatile organic compounds (VOC)and PM2.5chemical composition. This project was conducted by the National Reference Laboratory on air quality and thiswas the first time these measurements were assessed. A major part of the project was field and laboratory audits of the ongoing PAH and metal measurements. Other measurements were briefly evaluated through interviews and available literature. In addition, the national AQ database, the expertise of local measurement networks and related publications were utilised. In total, all theseven measurement networks performing PAH and metal measurements in 2019–2020took part in the audits. Eleven stations were audited while these measurements are performed at 22 AQ stations in Finland. For the large networks, one station was chosen to represent the performance of the network. The audits included also six laboratories performing the analysis of the collected samples. The audits revealed the compliance of the measurements with the AQ Decree 113/2017, Directive 2004/107/EC and Standards of the European Committee for Standardization(CEN). In addition, general information of the measurements, instruments and quality control procedures were gained. The results of the laboratory audits were confidential,but this report includes general findings, and the measurement networks were informed on the audit results with the permission of the participating laboratories. As a conclusion, the measurementmethodsusedwere mainly reference methods. Currently, all sampling methods were reference methods; however, before 2018 three networks used other methods that may have underestimated concentrations. Regarding these measurements, it should be noted the results are notcomparable with the reference method. Laboratory methods were reference methods excluding two cases, where the first was considered an acceptable equivalent method. For the other, a change to a reference method was strongly recommended and this realized in 2020. For some new measurements, the ongoing QC procedures were not yet fully established, and advice were given. Some networks used consultant for calibration and maintenance, and thus theywere not fully aware of the QC procedures. EN Standards were mostly followed. Main concerns were related to the checks of flow and calculation of measurement uncertainty, and suggestions for improvement were given. When the measurement networks implement the recommendations given inthe audits, it can be concluded that the EN Standards are adequately followed in the networks. In the ongoing sampling, clear factors risking the trueness of the result were not found. This applies also for the laboratory analyses in 2020. One network had concentrations above the target value, and theindicative measurementsshould be updated to fixed measurements.

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