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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

The anaerobic degradation of organic matter in Danish coastal sediments - Iron reduction, manganese reduction, and sulfate reduction

A combination of porewater and solid phase analysis as well as a series of sediment incubations are used to quantify organic carbon oxidation by dissimilatory Fe reduction, Mn reduction, and sulfate reduction, in sediments from the Skagerrak (located off the northeast coast of Jutland, Denmark). Solid phase data are integrated with incubation results to define the zones of the various oxidation processes. At S(9), surface Mn enrichments of up to 3.5 wt pct were found, and with such a ready source of Mn, dissimilatory Mn reduction was the only significant anaerobic process of carbon oxidation in the surface 10 cm of the sediment. At S(4) and S(6), active Mn reduction occurred; however, most of the Mn reduction may have resulted from the oxidation of acid volatile sulfides and Fe(2+) rather than by a dissimilatory sulfate. Dissolved Mn(2+) was found to completely adsorb onto sediment containing fully oxidized Mn oxides.

Canfield, Donald E.↗
NASA NTRS1996

Ammonia from Iron(II) Reduction of Nitrite and the Strecker Synthesis: Do Iron(II) and Cyanide Interfere with Each Other?

The question of whether the production of ammonia, from the reduction of nitrite by iron(II), is compatible with its use in the Strecker synthesis of amino acids, or whether the iron and the cyanide needed for the Strecker synthesis interfere with each other, is addressed. Results show that the presence of iron(II) appears to have little, or no, affect on the Strecker synthesis. The presence of cyanide does interfere with reduction of nitrite, but the reduction proceeds at cyanide/iron ratios of less than 4:1. At ratios of about 2:1 and less there is only a small effect. The two reactions can be combined to proceed in each other's presence, forming glycine from nitrite, Fe(+2), formaldehyde, and cyanide.

Summers, David P.↗
NASA NTRS1998

Ammonia from iron(II) reduction of nitrite and the Strecker synthesis: do iron(II) and cyanide interfere with each other?

The question of whether the production of ammonia, from the reduction of nitrite by iron(II), is compatible with its use in the Strecker synthesis of amino acids, or whether the iron and the cyanide needed for the Strecker synthesis interfere with each other, is addressed. Results show that the presence of iron(II) appears to have little, or no, effect on the Strecker synthesis. The presence of cyanide does interfere with reduction of nitrite, but the reduction proceeds at cyanide/iron ratios of less than 4:1. At ratios of about 2:1 and less there is only a small effect. The reduction of nitrite and the Strecker can be combined to proceed in each other's presence, to yield glycine from a mixture of nitrite, Fe+2, formaldehyde, and cyanide.

NASA Discipline Exobiology↗
NASA NTRS1994

Ammonia on the prebiotic Earth: Iron(II) reduction of nitrite

Theories for the origin of life require the availability of reduced nitrogen. In the non-reducing atmosphere suggested by geochemical evidence, production in the atmosphere and survival of NH3 against photochemical destruction are problematic. Electric discharges and impact shocks would produce NO rather than HCN or NH3. Conversion of NO to nitrous and nitric acid (by way of HNO) and precipitation in acid rain would provide a source of fixed nitrogen to the early ocean. One solution to the NH3 problem may have been the reduction of nitrite/nitrate in the ocean with aqueous ferrous iron, Fe(2+): 6Fe(+2) + 7 H2O + NO2(-) yields 3Fe2O3 + 11 H(+) + NH3. We have measured the kinetics of this reaction as a function of temperature, pH, and concentrations of salts, Fe(+2), and NO2(-). Cations (Na(+), Mg(2+), K(+)) and anions (Cl(-), Br(-), SO4(2-)) increase the rate by factors of 4 to 8. Although a competing pathway yields N2, the efficiency of the conversion of nitrite to ammonia ranges from 25% to 85%. Nitrate reduction was not consistently reproducible; however, when it was observed, its rate was slower by at least 8X than that of nitrite reduction. If the prebiotic atmosphere contained 0.2 to 10 atmospheres CO2 as suggested by Walker (1985), the Fe(+2) concentration and the rate would have been limited by siderite (FeCO3) solubility.

Summers, David P.↗
NASA NTRS2024

The Isotopic Composition of Molecular Water Formed by Hydrogen Reduction of Iron Oxides: A Proxy for Endogenous Water Formed From Solar Wind Implantation

Many workers have successfully utilized a variety of lunar materials to infer the sources and processing history of volatiles on the Moon. In situ techniques via NanoSIMS have enabled a plethora of hydrogen isotope measurements of isolated grains in regolith and apatite within igneous rocks, revealing an extraordinarily large range of δD values from ~ -900 to +1000‰. The lowest of these δD values are related to the incorporation of solar wind hydrogen, which is pure 1 H. Exposure to solar wind results in structural damage to crystalline phases, forming ubiquitous tens-to-hundreds of nanometer thick amorphous rims on mature regolith grains. Solar wind implantation of H + is also is also thought to result in the formation of nanophase Fe 0 (npFe), a quantitative metric of surface exposure time (e.g., Is/FeO). The formation of npFe can be generally described via the reaction: Fe 2+ O + H 2 = Fe 0 + H 2 O, resulting in the formation of endogenous molecular water reservoirs.

lunar water↗
NASA NTRS2010

Apparatus for Cold, Pressurized Biogeochemical Experiments

A laboratory apparatus has been devised as a means of studying plausible biogeochemical reactions under high-pressure, low-temperature aqueous, anaerobic conditions like those conjectured to prevail in a liquid water ocean on Europa (the fourth largest moon of the planet Jupiter). The experiments to be performed by use of this apparatus are intended to enhance understanding of how life (if any) could originate and evolve in the Europa ocean environment. Inasmuch as terrestrial barophilic, psychrophilic organisms that thrive under anaerobic conditions are used in the experiments, the experiments may also contribute to terrestrial biogeochemistry. The apparatus (see figure) includes a bolt-closure reaction vessel secured inside a refrigerator that maintains a temperature of 4 C. Pressurized water is supplied to the interior of the vessel by a hydrostatic pump, which is attached to the vessel via high-pressure fittings. The terrestrial organisms used in the experiments thus far have been several facultative barophilic, psychrophilic stains of Shewanella bacteria. In the experiments, these organisms have been tested for reduction of ferric ion by growing them in the presence of a ferric food source under optimized terrestrial conditions. The short-term goal of these experiments has been to select Shewanella strains that exhibit iron-reduction capability and test their ability to facilitate biogeochemical reduction of iron under temperature and pressure conditions imitating those in Europa s ocean. It is anticipated, that, once growth under Europa-like conditions has been achieved, the selected Shewanella strains will be used to facilitate biogeochemical reactions of sulfate and carbonate with hydrogen gas. Any disequilibrium of the products with the environment would be interpreted as signifying biogenic activity and the possibility of life in Europa s ocean.

Amashukeli, Xenia↗
NASA NTRS1999

Ceruloplasmin ferroxidase activity stimulates cellular iron uptake by a trivalent cation-specific transport mechanism

The balance required to maintain appropriate cellular and tissue iron levels has led to the evolution of multiple mechanisms to precisely regulate iron uptake from transferrin and low molecular weight iron chelates. A role for ceruloplasmin (Cp) in vertebrate iron metabolism is suggested by its potent ferroxidase activity catalyzing conversion of Fe2+ to Fe3+, by identification of yeast copper oxidases homologous to Cp that facilitate high affinity iron uptake, and by studies of "aceruloplasminemic" patients who have extensive iron deposits in multiple tissues. We have recently shown that Cp increases iron uptake by cultured HepG2 cells. In this report, we investigated the mechanism by which Cp stimulates cellular iron uptake. Cp stimulated the rate of non-transferrin 55Fe uptake by iron-deficient K562 cells by 2-3-fold, using a transferrin receptor-independent pathway. Induction of Cp-stimulated iron uptake by iron deficiency was blocked by actinomycin D and cycloheximide, consistent with a transcriptionally induced or regulated transporter. Cp-stimulated iron uptake was completely blocked by unlabeled Fe3+ and by other trivalent cations including Al3+, Ga3+, and Cr3+, but not by divalent cations. These results indicate that Cp utilizes a trivalent cation-specific transporter. Cp ferroxidase activity was required for iron uptake as shown by the ineffectiveness of two ferroxidase-deficient Cp preparations, copper-deficient Cp and thiomolybdate-treated Cp. We propose a model in which iron reduction and subsequent re-oxidation by Cp are essential for an iron uptake pathway with high ion specificity.

NASA Discipline Regulatory Physiology↗
NASA NTRS1998

The role of biomineralization in microbiologically influenced corrosion

Synthetic iron oxides (goethite, alpha-FeO.OH; hematite, Fe2O3; and ferrihydrite, Fe(OH)3) were used as model compounds to simulate the mineralogy of surface films on carbon steel. Dissolution of these oxides exposed to pure cultures of the metal-reducing bacterium, Shewanella putrefaciens, was followed by direct atomic absorption spectroscopy measurement of ferrous iron coupled with microscopic analyses using confocal laser scanning and environmental scanning electron microscopies. During an 8-day exposure the organism colonized mineral surfaces and reduced solid ferric oxides to soluble ferrous ions. Elemental composition, as monitored by energy dispersive x-ray spectroscopy, indicated mineral replacement reactions with both ferrihydrite and goethite as iron reduction occurred. When carbon steel electrodes were exposed to S. putrefaciens, microbiologically influenced corrosion was demonstrated electrochemically and microscopically.

Non-programmatic↗
NASA NTRS1979

Demand and supply of hydrogen as chemical feedstock in USA

Projections are made for the demand and supply of hydrogen as chemical feedstock in USA. Industrial sectors considered are petroleum refining, ammonia synthesis, methanol production, isocyanate manufacture, edible oil processing, coal liquefaction, fuel cell electricity generation, and direct iron reduction. Presently, almost all the hydrogen required is produced by reforming of natural gas or petroleum fractions. Specific needs and emphases are recommended for future research and development to produce hydrogen from other sources to meet the requirements of these industrial sectors. The data and the recommendations summarized in this paper are based on the Workshop 'Supply and Demand of Hydrogen as Chemical Feedstock' held at the University of Houston on December 12-14, 1977.

Huang, C. J.↗
NASA NTRS2003

The Stable Isotope Fractionation of Abiotic Reactions: A Benchmark in the Detection of Life

One very important tool in the analysis of biogenic, and potentially biogenic, samples is the study of their stable isotope distributions. The isotope distribution of a sample depends on the process(es) that created it. One important application of the analysis of C & N stable isotope ratios has been in the determination of whether organic matter in a sample is of biological origin or was produced abiotically. For example, the delta C-13 of organic material found embedded in phosphate grains was cited as a critical part of the evidence for life in 3.8 billion year old samples. The importance of such analysis in establishing biogenicity was highlighted again by the role this issue played in the recent debate over the validity of what had been accepted as the Earth s earliest microfossils. These kinds of analysis imply a comparison with the fractionation that one would have seen if the organic material had been produced by alternative, abiotic, pathways. Could abiotic reactions account for the same level of fractionation? Additionally, since the fractionation can vary between different abiotic reactions, understanding their fractionations can be important in distinguishing what reactions may have been significant in the formation of different abiological samples (such as extraterrestrial samples). There is however, a scarcity of data on the fractionation of carbon and nitrogen by abiotic reactions. In order to interpret properly what the stable isotope ratios of samples tell us about their biotic or abiotic nature, more needs to be known about how abiotic reactions fractionate C and N. Carbon isotope fractionations have been studied for a few abiotic processes. These studies presumed the presence of a reducing atmosphere, focusing on reactions involving spark discharge, W photolysis of reducing gas mixtures, and cyanide polymerization in the presence of ammonia. They did find that the initial products showed a depletion in I3C with values in the range of a few per mil to as low as -60 % (potentially comparable to that which accompanies the biosynthesis of organic matter). We need to understand what kind of fractionations are observed with reactions under the non-reducing or mildly reducing conditions now thought to be present on the early Earth. While nitrogen is receiving increased attention as a tool for these kinds of analyses, almost nothing is known about the isotope fractionation that one would expect for abiotic sources of fixed/reduced nitrogen. This project will measure the fixation from a series of abiotic reactions that may have been present on the early Earth (and other terrestrial planets) and produced organic material that could have ended up in the rock record. The work will look at a number of reactions, under a non- reducing, or mildly reducing, atmosphere, covering sources of prebiotic organic C & N from shock heating, to photochemistry, to hydrothermal reactions. Some reactions that we plan to study are; Shock heating of a non-reducing atmosphere to produce CO and NO (in collaboration with Chris McKay), formation of formaldehyde (and related compounds) from COY the formation of ammonia from nitrogen oxides (ultimately from NO) by ferrous iron reduction, and the hydrothermal synthesis of compounds including the hydrocarboxylation/hydrocarbonylation reaction (in collaboration with George Cody), reactions of oxalate to form hydrocarbons and other oxygenated compounds and the formation of lipids from oxalic/formic acid (in collaboration with Tom McCollom), and reactions of carbon monoxide & carbon dioxide with N2, ammonia or nitritehitrate to form hydrogen cyanide, nitriles, ammonia/amines and nitrous

Summers, David P.↗
NASA NTRS1992

Reduction of iron-bearing lunar minerals for the production of oxygen

The kinetics and mechanism of the reduction of simulants of the iron-bearing lunar minerals olivine ((Fe,Mg)2SiO4), pyroxene ((Fe,Mg,Ca)SiO3), and ilmenite (FeTiO3) are investigated, extending previous work with ilmenite. Fayalite is reduced by H2 at 1070 K to 1480 K. A layer of mixed silica glass and iron forms around an unreacted core. Reaction kinetics are influenced by permeation of hydrogen through this layer and a reaction step involving dissociated hydrogen. Reaction mechanisms are independent of Mg content. Augite, hypersthene, and hedenbergite are reduced in H2 at the same temperatures. The products are iron metal and lower iron silicates mixed throughout the mineral. Activation energy rises with calcium content. Ilmenite and fayalite are reduced with carbon deposited on partially reduced minerals via the CO disproportionation reaction. Reduction with carbon is rapid, showing the carbothermal reduction of lunar minerals is possible.

Massieon, Charles↗
NASA NTRS2012

Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at Approximately 40-50 GPa and Their Relevance to the Martian Regolith Component Present in Shergottites

Basaltic shergottites such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in Martian atmospheric gases [1] and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a Martian regolith component based on Sm and Kr isotopic studies [2]. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles [3, 4]. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in Martian meteorites. The material comprising these glasses arises from the highly oxidizing Martian surface and sulfur is unlikely to occur as sulfide in the Martian regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev [5]. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the Martian meteorites into space [6]. As a result of high energy deposition by shock (approx. 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H2 and CO which were shock-implanted from the Martian atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to shock pressures between 40 and 50 GPa under reducing conditions. The experimental products from the recovered samples were analyzed by SEM and microprobe techniques at JSC.

Rao, M. N.↗
NASA NTRS2017

Oxygen Extraction from Minerals

Oxygen, whether used as part of rocket bipropellant or for astronaut life support, is a key consumable for space exploration and commercialization. In Situ Resource Utilization (ISRU) has been proposed many times as a method for making space exploration more cost effective and sustainable. On planetary and asteroid surfaces the presence of minerals in the regolith that contain oxygen is very common, making them a potential oxygen resource. The majority of research and development for oxygen extraction from minerals has been for lunar regolith although this work would generally be applicable to regolith at other locations in space. This presentation will briefly survey the major methods investigated for oxygen extraction from regolith with a focus on the current status of those methods and possible future development pathways. The major oxygen production methods are (1) extraction from lunar ilmenite (FeTiO3) with either hydrogen or carbon monoxide, (2) carbothermal reduction of iron oxides and silicates with methane, and (3) molten regolith electrolysis (MRE) of silicates. Methods (1) and (2) have also been investigated in a two-step process using CO reduction and carbon deposition followed by carbothermal reduction. All three processes have byproducts that could also be used as resources. Hydrogen or carbon monoxide reduction produce iron metal in small amounts that could potentially be used as construction material. Carbothermal reduction also makes iron metal along with silicon metal and a glass with possible applications. MRE produces iron, silicon, aluminum, titanium, and glass, with higher silicon yields than carbothermal reduction. On Mars and possibly on some moons and asteroids, water is present in the form of mineral hydrates, hydroxyl (-OH) groups on minerals, andor water adsorbed on mineral surfaces. Heating of the minerals can liberate the water which can be electrolyzed to provide a source of oxygen as well. The chemistry of these processes, some key development and demonstration projects, the challenges remaining to be overcome, and possible future directions will be discussed with a goal of increased understanding of these important ISRU technologies and their potential applications to space exploration and settlement.

propellant production↗
NASA NTRS1990

Carbonate petrography, kerogen distribution, and carbon and oxygen isotope variations in an early Proterozoic transition from limestone to iron-formation deposition, Transvaal Supergroup, South Africa

The transition zone comprises Campbellrand microbialaminated (replacing "cryptalgalaminate") limestone and shale, with minor dolomite, conformably overlain by the Kuruman Iron Formation of which the basal part is characterized by siderite-rich microbanded iron-formation with minor magnetite and some hematite-containing units. The iron-formation contains subordinate intraclastic and microbialaminated siderite mesobands and was deposited in deeper water than the limestones. The sequence is virtually unaltered with diagenetic mineral assemblages reflecting a temperature interval of about 110 degrees to 170 degrees C and pressures of 2 kbars. Carbonate minerals in the different rock types are represented by primary micritic precipitates (now recrystallized to microsparite), early precompactional sparry cements and concretions, deep burial limpid euhedral sparites, and spar cements precipitated from metamorphic fluids in close contact with diabase sills. Paragenetic pathways of the carbonate minerals are broadly similar in all lithofacies with kerogen intimately associated with them. Kerogen occurs as pigmentation in carbonate crystals, as reworked organic detritus in clastic-textured carbonate units, and as segregations of kerogen pigment around late diagenetic carbonate crystals. Locally kerogen may also be replaced by carbonate spar. Carbon isotope compositions of the carbonate minerals and kerogen are dependent on their mode of occurrence and on the composition of the dominant carbonate species in a specific lithofacies. Integration of sedimentary, petrographic, geochemical, and isotopic results makes it possible to distinguish between depositional, early diagenetic, deep burial, and metamorphic effects on the isotopic compositions of the carbonate minerals and the kerogen in the sequence. Major conclusions are that deep burial thermal decarboxylation led to 13C depletion in euhedral ferroan sparites and 13C enrichment in kerogen (organic carbon). Metamorphic sparites are most depleted in 13C. Carbonates in oxide-rich iron-formations are more depleted in 13C than those in siderite-rich iron-formation whereas the kerogens in oxide banded iron-formations (BIF) are more enriched. This implies that the siderite-rich iron-formations were not derived from oxide-rich iron-formation through reduction of ferric iron by organic matter. Organic matter oxidation by ferric iron did, however, decrease the abundance of kerogen in oxide-rich iron-formation and led to the formation of isotopically very light sparry carbonates. Siderite and calcmicrosparite both represent recrystallized primary micritic precipitates but differ in their 13C composition, with the siderites depleted in 13C by 4.6 per mil on average relative to calcmicrosparite. This means that the siderites were precipitated from water with dissolved inorganic carbon depleted in 13C by about 9 per mil relative to that from which the limestones precipitated. This implies an ocean system stratified with regard to total carbonate, with the deeper water, from which siderite-rich iron-formation formed, depleted in 13C. Iron-formations were deposited in areas of very low organic matter supply. Depletion of 13C may, therefore, derive not from degradation of organic matter but from hydrothermal activity, a conclusion which is supported by 18O composition of the carbonate minerals and trace element and rare earth element (REE) compositions of the iron-formations.

NASA Discipline Number 52-30↗
NASA NTRS1976

The surface structure and composition of 60017,43

A surface fragment of 60017, itself an exposed section of Shadow Rock, has been characterized structurally and chemically using gas adsorption, helium pycnometry, scanning electron microscopy, and Auger and ESCA spectroscopy. The fragment is seen as a partially melted devitrified-glass impact breccia possessing a relatively low surface area, macroporosity, and low absolute density. The fragment appears to be plagioclase-enriched with respect to 60017 and to possess significant surface heterogeneity. Confirmation of the surface reduction of iron was obtained; however, the extent of this reduction varied from point to point. Significant amounts of surface volatiles were also found, and it is hypothesized that these were released during the North Ray cratering event. If this is proved correct, similar volatile concentrations should be found on other North Ray ejecta.

Cadenhead, D. A.↗
NASA NTRS1994

Iron and manganese in anaerobic respiration: environmental significance, physiology, and regulation

Dissimilatory iron and/or manganese reduction is known to occur in several organisms, including anaerobic sulfur-reducing organisms such as Geobacter metallireducens or Desulfuromonas acetoxidans, and facultative aerobes such as Shewanella putrefaciens. These bacteria couple both carbon oxidation and growth to the reduction of these metals, and inhibitor and competition experiments suggest that Mn(IV) and Fe(III) are efficient electron acceptors similar to nitrate in redox abilities and capable of out-competing electron acceptors of lower potential, such as sulfate (sulfate reduction) or CO2 (methanogenesis). Field studies of iron and/or manganese reduction suggest that organisms with such metabolic abilities play important roles in coupling the oxidation of organic carbon to metal reduction under anaerobic conditions. Because both iron and manganese oxides are solids or colloids, they tend to settle downward in aquatic environments, providing a physical mechanism for the movement of oxidizing potential into anoxic zones. The resulting biogeochemical metal cycles have a strong impact on many other elements including carbon, sulfur, phosphorous, and trace metals.

Review, Academic↗